/'BERKELEY' 
LIBRARY 

OF 
\CAUfORNIA 

EARTN 

SCIENCES 

LIBRARY 


^-^^-^-ojc^c^c^-i^s--^       ££>£-     t 

— ^y 


MANUAL    OF   GEOLOGY 


TREATING  OF  THE  PRINCIPLES   OF  THE   SCIENCE 

WITH  SPECIAL  REFERENCE  TO  AMERICAN 

GEOLOGICAL   HISTORY 


BY 

JAMES  D.  DANA 

PROFESSOR   EMERITUS  OF  GEOLOGY  AND  MINERALOGY   IN  YALE   UNIVERSITY:    AUTHOR  OP 

A  SYSTEM  OF  MINERALOGY;   CORALS  AND  CORAL  ISLANDS;   VOLCANOES;  REPORTS 

OF  WILKES'S  EXPLORING  EXPEDITION,   ON  GEOLOGY,  ON 

ZOOPHYTES,  AND  ON   CRUSTACEA,   ETC. 


"Speak  to  the  Earth  and  it  shall  teach  thee" 


ILLUSTRATED  BY  OVER  FIFTEEN  HUNDRED  AND  SEVENTY-FIVE  FIGURES 
IN  THE  TEXT,  AND  TWO  DOUBLE-PAGE  MAPS 


FOURTH   EDITION 


NEW  YORK-:. CINCINNATI-:. CHICAGO 

AMERICAN    BOOK    COMPANY 

LONDON:   TRtfBNER   AND   CO. 

1896 


MATTHEW  LIBRARX 

COPYRIGHT,  1894. 

BY  JAMES  D.  DANA 

w.  p.  3 


PREFACE. 


IN  the  preparation  of  the  new  edition  of  this  Manual,  the  work  has 
been  wholly  rewritten.  North  American  Geological  History  is  still,  how- 
ever, its  chief  subject.  The  time  divisions  in  this  history,  based  on  the 
ascertained  subdivisions  of  the  formations,  were  first  brought  out  in  my 
Address  before  the  meeting  of  the  American  Association  at  Providence  in 
1855 ;  and  in  1863,  the  "  continuous  history  "  appeared  in  the  first  edition 
of  this  Manual,  written  up  ironi  the  State  reports  and  other  geological  pub- 
lications. The  idea,  long  before  recognized,  that  all  observations  on  the 
rocks,  however  local,  bore  directly  on  the  stages  in  the  growth  of  the  Con- 
tinent derives  universal  importance  from  the  recognition  of  North  America 
as  the  world's  type-continent — the  only  continent  that  gives,  in  a  full  and 
simple  way,  the  fundamental  principles  of  continental  development. 

Since  1863,  when  the  first  edition  of  this  work  was  published,  investi- 
gation, through  the  geological  workers  of  the  United  States,  Canada,  and 
Mexico,  has  been  extended  over  nearly  all  parts  of  the  continent,  so  that  its 
history  admits  of  being  written  out  with  much  fullness.  The  Government 
Expeditions  over  the  Rocky  Mountain  region,  under  F.  V.  HAYDEN,  CLAR- 
ENCE KING,  CAPTAIN  WHEELER  and  others,  and  earlier,  those  especially  of 
the  Pacific  Railroad  Explorations,  and  the  Mexican  Boundary  Commission, 
were  large  contributors  to  this  result ;  and  also,  since  1879,  the  able  corps  of 
the  United  States  Geological  Survey. 

As  the  rewritten  book  shows,  new  principles,  new  theories,  and  widely 
diverse  opinions  on  various  subjects  are  among  the  later  contributions,  along 
with  a  profusion  of  new  facts  relating  to  all  departments  of  the  science. 

The  Cambrian  formation  has  been  traced  through  a  large  part  of  the 
continent,  and  the  number  of  its  fossils  has  been  increased,  chiefly  by  C.  D. 
WALCOTT,  from  a  few  to  hundreds.  The  Appalachian  Mountain  structure 
has  been  shown  by  CLARENCE  KING,  Dr.  G.  M.  DAWSON,  and  R.  G.  MCDON- 
NELL to  have  been  repeated  in  the  great  post-Cretaceous  mountain-making 
of  the  Rocky  Mountain  region.  The  Reptiles,  Birds,  and  Mammals  of  the 
Mesozoic  and  Tertiary  have  continued  coming  from  the  rocks  until  the 
species  recognized  much  outnumber  those  of  any  other  continent.  The  canons 
and  other  results  of  erosion  in  the  west  have  thrown  new  light,  through 
their  investigators,  on  the  work  of  the  waters.  Besides,  the  science  of 


4  PREFACE. 

petrology  lias  elucidated  ^inuch  of  the  obscure  in  the  constitution,  relations, 
and, -origin:  cf  :rocksj  ^  t  ,\ 

Moreover,  America;  ^froni  early  in  the  century,  has  been  receiving 
instruction  through  the  development  and  parallel  progress  of  the  Science 
in  Europe  and  Other  lands. 

The  first  edition  of  this  Manual  owed  much  to  the  advice  of  the  able 
paleontologist,  F.  B.  MEEK,  and  also  to  his  skill  as  a  draftsman;  and  the 
work  still  bears  prominent  evidence  of  his  knowledge,  judgment,  and  scru- 
pulous exactness,  traits  which  give  a  permanent  value  to  all  the  results  of 
his  too  soon  ended  labors. 

In  this  new  edition,  the  Paleozoic  paleontology  is  largely  indebted  to 
PROFESSOR  C.  E.  BEECHER  and  PROFESSOR  H.  S.  WILLIAMS  ;  the  Jurassic, 
of  western  America,  to  PROFESSOR  A.  HYATT  ;  the  Cretaceous,  to  PROFESSOR 
HYATT,  MR.  T.  W.  STANTON,  MR.  E.  P.  WHITFIELD,  and  PROFESSOR  R.  T. 
HILL  ;  and  the  Tertiary,  as  regards  the  Invertebrates,  to  PROFESSOR  G.  D. 
HARRIS.  With  respect  to  the  Vertebrates  of  the  Jurassic,  Cretaceous,  and 
Tertiary,  very  valuable  aid  has  been  received  from  PROFESSOR  MARSH,  and 
also  in  the  part  on  Tertiary  Mammals  from  PROFESSOR  W.  B.  SCOTT.  The 
account  of  the  arrangement  and  distribution  of  the  Jurassic  and  Cretaceous 
rocks  of  western  America  was  prepared  with  the  assistance  of  MR.  J.  S. 
DILLER  ;  and  that  with  regard  to  the  marine  Tertiary  of  the  country  was 
chiefly  written  for  its  place  by  PROFESSOR  HARRIS.  I  am  further  indebted 
to  PROFESSOR  A.  E.  VERRILL  for  his  revision  of  the  pages  on  the  Animal 
Kingdom. 

Moreover,  the  replies  to  requests  for  information  have  placed  me  under 
obligation  to  almost  all  the  geologists  of  the  Continent,  those  of  Canada  as 
well  as  the  United  States,  —  and  especially  to  SIR  WILLIAM  DAWSON,  MR. 
A.  R.  C.  SELWYN,  DR.  G.  M.  DAWSON,  MR.  CLARENCE  KING,  MR.  C.  D. 
WALCOTT,  PROFESSOR  N.  S.  SHALER,  PROFESSOR  S.  H.  SCUDDER,  MR. 
FRANK  LEVERETT,  PROFESSOR  R.  T.  HILL,  PROFESSOR  W.  UPHAM,  PRO- 
FESSOR G.  F.  WRIGHT,  PROFESSOR  J.  J.  STEVENSON,  MR.  WM.  H.  BALL, 
DR.  C.  A.  WHITE,  and  PROFESSOR  J.  P.  IDDINGS. 

Throughout  this  volume,  the  dates  of  papers  containing  cited  facts  or 
views  are  often  stated.  If  a  condensed  bibliography,  containing  in  brief 
form  the  titles  of  the  most  important  geological  and  paleontological  works 
and  papers,  arranged  under  the  year  of  publication,  were  accessible  to  the 
student,  these  dates  would  be  a  sufficient  means  of  reference.  Without 
such  a  Bibliography  they  may  serve  as  a  help  in  consulting,  besides  Reports 
of  Geological  Surveys,  the  serial  scientific  publications.  It  is  best  to  com- 
mence the  search  with  the  periodical  containing  the  most  geological  papers, 
notes,  and  book  notices,  and  follow  on  with  the  others.  The  American 
Journal  of  Science  commenced  in  1818;  the  American  Naturalist,  in 
1868;  the  American  Geologist,  in  1888;  the  Bulletin  of  the  American 
Geological  Society,  in  1890;  the  Journal  of  Geology,  Chicago,  in  1893. 
Then  refer  to  the  Proceedings  and  Memoirs  of  American  Scientific  Soci- 


PREFACE.  5 

eties  or  Academies,  in  the  following  order:  Academy  of  Natural  Sciences 
of  Philadelphia ;  American  Philosophical  Society,  Philadelphia ;  Society  of 
Natural  History,  Boston ;  American  Academy,  Boston ;  Lyceum  of  Natural 
History,  and  later,  Academy  of  Sciences,  New  York;  and  so  on,  not  over- 
looking the  Reports  of  the  American  Association  for  the  Advancement  of 
Science.  The  foreign  serial  works  of  most  importance  to  the  geologist  are 
the  Journal  of  the  Geological  Society  of  London ;  the  Geological  Magazine, 
London ;  Bulletin  of  the  Geological  Society  of  France  ;  "  Comptes  Eendus  " 
of  the  Academy  of  Sciences,  Paris ;  Jahrbuch  fur  Mineralogie,  Geologic  und 
Palaeontologie,  Stuttgart;  Zeitschrift  der  deutschen  geologischen  Gesell- 
schaft,  Berlin ;  Jahrbuch  der  k.-k.  geologischen  Eeichsanstalt,  Vienna. 

For  foreign  facts  and  views  I  am  largely  indebted  to  the  able  English 
works  of  SIR  ARCHIBALD  GEIKIE,  PROFESSOR  PRESTWICH,  and  PROFESSORS 
ETHERIDGE  and  SEELEY,  the  very  full  Traite  de  Geologic  of  PROFESSOR 
A.  DE  LAPPARENT,  and  the  Elemente  der  Geologic  of  DR.  CREDNER. 

As  the  volume  is  necessarily  larger  than  that  of  the  edition  of  1880,  — 
partly  through  more  text,  but  also  through  a  greater  profusion  of  illustra- 
tions, —  the  instructor  may  find  it  convenient,  in  his  use  of  the  Historical 
part,  to  take  up  successively  its  two  great  subjects,  the  geological  and 
physical  history  of  the  continents,  and  the  history  of  its  life. 

JAMES   D.   DANA. 
NEW  HAVEN,  CONN.,  January,  1895. 


TABLE  OF   CONTENTS. 


INTRODUCTION. 

Relations  of  the  Science  of  Geology 
Subdivisions  of  Geology   .... 


PAGE 

9 
13 


PART  I.  —  Physiographic  Geology. 

1.  The  Earth's  General  Contour  and 

Surface  Subdivisions     ....       15 

2.  System  in  the  Reliefs  of  the  Land  .       30 

3.  System  in  the  Courses  of  the  Earth's 

Feature  Lines 35 

4.  Oceanic    and   Atmospheric  Move- 

ments and  Temperature     ...       42 

5.  Geographical  Distribution  of  Plants 

and  Animals 52 

PART  II.  —  Structural  Geology. 

1.  Rocks:  their  Constituents  and  Kinds      61 

2.  Terranes  :  their  Constitution,  Char- 

acteristics,   Positions,    and    Ar- 
rangement   89 

PART  III.  — Dynamical  Geology. 

Agencies  and  General  Subdivisions     .     117 

1.  Chemical  Work 118 

2.  Life:    its   Mechanical   Work    and 

Rock  Contributions 140 

General  Remarks  on  Rock-making  141 
Protective  and  Other  Beneficial 

Effects 155 

Transporting  Effects 156 

Destructive  Effects 157 

3.  The  Atmosphere  as  a  Mechanical 

Agent 158 

4.  Water  as  a  Mechanical  Agent    .     .  166 
Fresh  Waters  :  Rivers  and  Lakes   .  171 

The  Ocean 209 

Freezing      and     Frozen      Water: 

Glaciers,  Icebergs 230 


5.  Heat      ..........     253 

1.  Sources  of  Heat  ......    253 

2.  Expansion  and  Contraction  .     .     259- 

3.  Igneous  Action  and  its  Results    265 
Volcanoes  ........     267 

Non-volcanic  Igneous  Eruptions     297 
Thermal  Waters,  Geysers     .     .    305 

4.  Metamorphism    ......     30& 

5.  Mineral  Veins,  Lodes,  Local  Ore 

Deposits      .....     .     .     327 

6.  Hypogeic    Work:     Earth-shaping, 

Mountain-making     ....     345 

1.  Characteristics  of  Disturbed 

Regions  and  Mountains  .     .  351 

2.  Subordinate  Effects  attending 

Orographic  Movements  :  Ef- 
fects from  Pressure,  Earth- 
quakes .......  369 

3.  Originof  tli  e  Earth's  Form  and 

Features  :  Orogenic  Work, 
Epeirogenic  Work  .  .  .  376 


PART  IV.  —  Historical  Geology. 

Subdivisions  in  Geological  History      .  397 

Review  of  the  System  of  Life     .     .     .  413 

1.  Animal  Kingdom  ......  414 

2.  Vegetable  Kingdom  .....  434 


I.  ARCHAEAN  TIME      . 

1.  Subdivisions:  Rocks 

2.  Life    . 


440 
445 

453 


II.  PALEOZOIC   TIME       ....  460 

I.  Cambrian  Era 462 

1.  North  American     ....  464 

1.  Lower  Cambrian  Period  470' 

2.  Middle  Cambrian  Period  474 

3.  Upper  Cambrian  Period  476 


TABLE   OF   CONTENTS. 


2.  Foreign 480 

3.  Geographical  and  Physical 

Conditions  and  Progress .  483 

II.  Lower  Silurian  Era    ....  489 

1.  North  American    ....  489 

2.  European     .     .     ....  517 

3.  General  Observations : 

Rocks  ;  Climate  ;  Biologi- 
cal Progress 524 

4.  Upturning  at  the  close  of  the 

Lower  Silurian  ...     .  526 

III.  Upper  Silurian  Era    ....  535 

1.  North  American    ....  535 

1.  Niagara  Period       ...  538 

2.  Onondaga  Period  .     .     .  552 

3.  Lower  Helderberg  Period  558 

2.  Foreign 563 

3.  General  Observations  :  Geo- 

logical ;        Geographical ; 

Biological 670 

IV.  Devonian  Era 675 

1.  North  American    ....  575 

1.  Oriskany  Period    .     .     .  577 

2.  Corniferous  Period    .     .  679 

3.  Hamilton  Period    ...  592 

4.  Chemung  Period'  .     .     .  602 

2.  Foreign 622 

3.  General  Observations :  Geo- 

logical ;  Geographical  .     .  628 

4.  Upturning  at  the  close  of 

the  Devonian     ....  630 

V.  Carbonic  Era 631 

1.  North  American    ....  633 

1.  Subcarboniferous  Period  636 

2.  Carboniferous  Period      .  647 

3.  Permian  Period     ...  660 

2.  Foreign 693 

3.  General  Observations :  Geo- 

logical and  Geographical ; 
Meteorological ;     Forma- 
tion of  Coal       ....  708 
General  Observations  on  Paleozoic 

Time .  714 

Post-Paleozoic,    or    Appalachian, 

Revolution  728 


Topographic  Changes  in  the  Indian 

Ocean :  Gondwana  Land  .     .     .  737 

III.  MESOZOIC   TIME 738 

1.  American  Triassic  and  Jurassic 

Period 739 

2.  Foreign  Triassic  and  Jurassic  .  768 

3.  General  Observations :    Conti- 

nental Comparisons;  Cli- 
mate ;  Biological  Changes  ; 
Upturnings  and  Mountain- 
making  791 

4.  American  Cretaceous  Period  .  812 

5.  Foreign 856 

6.  General  Observations:  Geologi- 

cal ;    Geographical ;    Biolog- 
ical; Gondwana  Land     .     .  867 
Post-Mesozoic  Revolution  .     .     .  874 

IV.  CENOZOIC  TIME 879 

I.  Tertiary  Era 879 

1.  North  American    ....  880 

2.  Foreign 919 

3.  General  Observations  :  Bio- 

logical ;      Orogenic    and 

Epeirogenic  ;  Climate      .  928 

II.  Quaternary  Era 940 

1.  Glacial  Period  .....  943 

1.  American 943 

2.  Foreign 975 

3.  Cause  of  Glacial  Climate  978 

2.  Champlain  Period      ...  981 

1.  American 98.1 

2.  Foreign 996 

3.  Pleistocene  Life     ....  997 

4.  Recent  Period 1012 

General  Observations :  Biolog- 
ical ;    Antarctic   Continent ; 
Epeirogenic 1016 

General   Observations   on   Geological 

History 1023 

Geological  Time 1023 

Climate  ;  the  Earth's  Development    .  1026 
Progress  in  the  Earth's  Life ....  1028 


ABBREVIATIONS. 


Ag.-L. 


B.  —  E.  Billings. 
Barr. — J.  Barrande. 
Beyr. — E.  Bey  rich. 
Blum.  — J.  F.  Blumenbach. 
Blv.— D.  de  BlainviUe. 
Br.  —  H.  G.  Bronn. 
Brngt.  —  Brongniart. 
Brod.  —  Broderip. 
Bu.  —  L.  von  Buch. 

Con.  — T.  A.  Conrad. 

D.— J.  D.  Dana. 
Dalm.— J.  W.  Dalman. 
Dav.  —  T.  Davidson. 
Def  r.  —  Def  ranee. 
Desh.  —  G.  P.  Deshayes. 
Dawson,  Dn.  —  Sir  Wm.  Daw- 
son. 
D'Orb.  —  Alcide  d'Orbigny. 

E.  &  H.  —  Edwards  &  Haime. 
Ehr.  —  Ch.  G.  Ehrenberg. 
Eich.  — E.  Eichwald. 
Emmr.  —  H.  F.  Emmrich. 

Fabr.  — Fabricius. 
Falc.  — H.  Falconer. 
Flem.  —  J.  Fleming. 
Fer.  —  Ferussac. 

G.  &  H.  —  Gabb  &  Horn. 


Gem.  —  Geinitz. 
Gld.  — Gould. 
Gm.  —  Gmelin. 
Gopp.  — H.  R.  Goppert. 
Goldf.  — Goldfuss. 

H.— J.  Hall. 
H.  &  M.  —  Hall  &  Meek. 
Hald.  — S.  S.  Haldeman. 
Hising.  —  W.  Hisinger. 
Hk.  — E.  Hitchcock. 
Hux.— T.H.Huxley. 

Kon.  —  L.  de  Koninck. 

L.— J.  Leidy. 

L.  &  H.  — Lindley  &  Hutton. 

Lam .  —  Lamarck . 

Linn.  —  Linnaeus. 

Lmx.  —  Lamouroux. 

Lsqx.,  Lx.  —  L.  Lesquereux. 

Lye. — Lycett. 

M.— F.  B.  Meek. 

Mant.  — G.  Mantell. 

Mey .  —  H.  von  Meyer. 

Mh.  —  O.C.  Marsh. 

Montf.  —  Denys  de  Montfort. 

Morr.  —  Morris. 

Mort.  —  S.  G.  Morton. 

Mull.  —  Mtiller. 

Murch.  —  R.  I.  Murchison. 


N.  &  P.  —  Norwood  &  Pratten.     Woodw.  —  J.  Woodward. 


N.  &  W.  —  Newberry  &  Worth- 

en. 
Newb.  — J.  S.  Newberry. 

O.  &  N.  — Owen  &  Norwood. 
Ow.  — R.  Owen  (London). 

Pack.  —  A.  S.  Packard. 
Phill.— J.  Phillips. 
Plien.  — T.  Plieninger. 
Portl.— J.  E.  Portlock. 

R.  —  F.  Romer. 
Rem.  —  A.  RemoncL 

S.  — J.  W.  Salter. 
Saff.— J.  M.Safford. 
Sc.  — S.  H.  Scudder. 
Schafh.  —  Schafhautl. 
Schlot.— E.  F.  von  Schlotheim. 
Schp.  —  W.  P.  Schimper. 
Sedg.  —  A.  Sedgwick. 
Shum.  — B.  F.  Shumard. 
Sow.  —  Sowerby. 
St.  —  Stokes. 

Sternb. — K.  von  Sternberg. 
Suck.  —  Suckow. 

Ung.  —  Unger. 

Van.  —  Vanuxem. 
Vern.— E.  de  Verneuil. 


INTRODUCTION. 


Kingdoms  of  nature.  —  SCIENCE,  in  her  survey  of  the  earth,  has  recog- 
nized three  kingdoms  of  nature,  —  the  animal,  the  vegetable,  and  the 
inorganic ;  or,  naming  them  from  the  forms  characteristic  of  each,  the 

ANIMAL    KINGDOM,    the    PLANT    KINGDOM,    and     the    CRYSTAL     KINGDOM.       An 

individual   in   either   kingdom   has   its   systematic   mode   of   formation  or 
growth. 

The  plant  or  animal,  (1)  endowed  with  life,  (2)  commences  from  a  germ, 
(3)  grows  by  means  of  imbibed  nutriment,  and  (4)  passes  through  a  series 
of  changes  and  gradual  development  to  the  adult  state,  when  (5)  it  evolves 
new  seeds  or  germs,  and  (6)  afterward  continues  on  to  death  and  dissolution. 

It  has,  hence,  its  cycle  of  growth  and  reproduction,  and  cycle  follows 
cycle  in  indefinite  continuance. 

The  crystal  is  (1)  a  lifeless  object,  and  has  a  simpler  history ;  it  (2) 
begins  in  a  nucleal  molecule  or  particle  ;  (3)  it  enlarges  by  external  addition 
or  accretion  alone ;  and  (4)  there  is,  hence,  no  proper  development,  as  the 
crystal  is  perfect,  however  minute ;  (5)  it  ends  in  simply  existing,  and  not 
in  reproducing ;  and,  (6)  being  lifeless,  there  is  no  proper  death  or  necessary 
dissolution. 

Such  are  the  individualities  in  the  great  kingdoms  of  nature  displayed 
upon  the  earth. 

But  the  earth  also,  according  to  Geology,  has  been  brought  to  its  present 
•condition  through  a  series  of  changes  or  progressive  formations,  and  from 
a  state  as  utterly  featureless  as  a  germ.  Moreover,  like  any  plant  or  animal, 
it  has  its  special  systems  of  interior  and  exterior  structure,  and  of  interior 
and  exterior  conditions,  movements,  and  changes ;  and,  although  Infinite 
Mind  has  guided  all  events  toward  the  great  end,  —  a  world  for  mind,  —  the 
earth  has,  under  this  guidance  and  appointed  law,  passed  through  a  regular 
course  of  history  or  growth.  Having,  therefore,  as  a  sphere,  its  comprehen- 
sive system  of  growth,  it  is  a  unit  or  individuality,  not,  indeed,  in  either  of 
the  three  kingdoms  of  nature  which  have  been  mentioned,  but  in  a  wider,  — 
a  WORLD  KINGDOM.  Every  sphere  in  space  must  have  had  a  related 
system  of  growth,  and  all  are,  in  fact,  individualities  in  this  Kingdom  of 
Worlds. 

9 


10  INTRODUCTION. 

Geology  treats  of  the  earth  in  this  grand  relation.  It  is  as  much  removec}: 
from  Mineralogy  as  from  Botany  and  Zoology.  It  uses  all  these  depart- 
ments; for  the  species  under  them  are  the  objects  which  make  up  the 
earth  and  enter  into  geological  history.  The  science  of  minerals  is  more 
immediately  important  to  the  geologist,  because  aggregations  of  minerals 
constitute  rocks,  or  the  plastic  material  in  which  the  records  of  the  past 
were  made. 

The  earth,  regarded  as  such  an  individuality  in  a  world  kingdom,  has  not 
only  its  comprehensive  system  of  growth,  in  which  strata  have  been  added 
to  strata,  continents  and  seas  defined,  mountains  reared,  and  valleys,  rivers,, 
and  plains  formed,  all  in  orderly  plan,  but  also  a  system  of  currents  in  its 
oceans  and  atmosphere,  —  the  earth's  circulating-system  ;  its  equally  world- 
wide system  in  the  distribution  of  heat,  light,  moisture,  and  magnetism,  and 
of  plants  and  animals;  its  system  of  secular  variations  (daily,  annual,  etc.) 
in  its  climate  and  all  meteorological  phenomena.  In  these  characteristics 
the  sphere  before  us  is  an  individual,  as  much  as  a  dog,  or  a  tree  ;  and,  to 
arrive  at  any  correct  views  on  these  subjects,  the  world  must  be  regarded  in 
this  capacity.  The  distribution  of  man  and  nations,  and  of  all  productions 
that  pertain  to  man's  welfare,  comes  in  under  the  same  grand  relation ;  for,, 
in  helping  to  carry  forward  man's  progress  as  a  race,  the  sphere  is  working 
out  its  final  purpose.  There  are,  therefore, 

Three  departments  of  science,  arising  out  of  this  individual  capacity  of 
the  earth. 

I.  GEOLOGY,  which  treats  of  (1)  the  earth's  structure,  and  (2)  its  system 
of  development, — the  latter  including  its  progress  in  rocks,  lands,  seas, 
mountains,  etc. ;  its  progress  in  all  physical  conditions,  as  heat,  moisture, 
etc. ;  its  progress  in  life,  or  its  vegetable  and  animal  tribes. 

II.  PHYSIOGRAPHY,  which  begins  where  Geology  ends, — that  is,  with 
the  adult  or  finished  earth,  —  and  treats  (1)  of  the  earth's  final  surface- 
arrangements  (as  to  its  features,  climates,  magnetism,  life,  etc.);  and  (2)  of 
its  system  of  physical  movements  or  changes  (as  atmospheric  and  oceanic 
currents,  and  other  secular  variations  in  heat,  moisture,  magnetism,  etc.). 

III.  THE  EARTH  WITH  REFERENCE  TO  MAN  (including   ordinary  Geog- 
raphy):  (1)  the  distribution  of  races  or  nations,  and  of  all  productions  or 
conditions  bearing  on  the  welfare  of  man  or  nations  ;  and  (2)  the  progressive 
changes  of  races  and  nations. 

The  first  of  these  departments  considers  the  structure  and  growth  of  the 
earth ;  the  second,  its  features  and  world-wide  activities  in  its  finished  state ; 
the  third,  the  fulfillment  of  its  purpose  in  man. 

Relation  of  the  earth  to  the  universe.  —  While  recognizing  the  earth  as 
a  sphere  in  a  world  kingdom,  it  is  also  important  to  observe  that  it  holds 
a  very  subordinate  position  in  the  system  of  the  heavens.  It  is  one  of  the 
smaller  satellites  of  the  sun,  —  its  size  about  ^ooooo  that  °^  the  sun*  Ami 
the  planetary  system  to  which  it  belongs,  although  3,000,000,000  of  miles 
in  radius,  is  but  one  among  myriads,  the  nearest  star  being  7000  times 


INTRODUCTION.  11 

farther  off  than  Neptune.  Thus  it  appears  that  the  earth  is  a  very  small 
object  in  the  universe.  Hence  we  naturally  conclude  that  it  is  a  dependent 
part  of  the  solar  system ;  that,  as  a  satellite  of  the  sun,  in  conjunction  with 
other  planets,  it  could  no  more  have  existed  before  the  sun,  or  our  planetary 
system  before  the  universe  of  which  it  is  a  part,  than  the  hand  before  the 
body  which  it  obediently  attends. 

Although  thus  diminutive,  the  laws  of  the  earth  are  the  laws  of  the 
universe.  One  of  the  fundamental  laws  of  matter  is  gravitation;  and  this 
we  trace  not  only  through  our  planetary  system,  but  among  the  fixed  stars, 
and  thus  know  that  one  law  pervades  the  universe. 

The  rays  of  light  which  come  in  from  the  remote  limits  of  space  are 
a  visible  declaration  of  unity;  for  this  light  depends  on  molecular  vibra- 
tions, — that  is,  the  ultimate  constitution  and  mode  of  action  of  matter ;  and, 
by  the  identity  of  its  principles  or  laws,  whatever  its  source,  it  proves  the 
essential  identity  of  the  molecules  of  matter. 

Meteoric  stones  are  specimens  of  celestial  bodies  occasionally  reaching 
us  from  the  heavens.  They  exemplify  the  same  chemical  and  crystal- 
lographic  laws  as  the  rocks  of  the  earth,  and  have  afforded  no  new  element 
or  principle  of  any  kind. 

The  moon  presents  to  the  telescope  a  surface  covered  with  the  craters  of 
volcanoes,  having  forms  that  are  well  illustrated  by  some  of  the  earth's 
volcanoes,  although  of  immense  size.  The  principles  exemplified  on  the 
earth  are  but  repeated  in  her  satellite. 

Thus,  from  gravitation,  light,  meteorites,  and  the  earth's  satellite,  we 
learn  that  there  is  oneness  of  law  through  space.  The  elements  may  differ 
in  different  systems,  but  it  is  a  difference  such  as  exists  among  known 
elements,  and  even  if  exemplifying  new  laws,  such  laws  cannot  be  at 
variance  with  those  illustrated  by  nature  within  reach  of  terrestrial  investi- 
gation. The  universe,  if  open  throughout  to  our  explorations,  would  vastly 
expand  our  knowledge,  and  science  might  have  a  more  beautiful  superstruc- 
ture, but  its  basement-laws  would  be  the  same.  A  treatise  on  Celestial 
Mechanics  printed  in  our  printing-offices  would  serve  for  the  universe. 

The  earth,  therefore,  although  but  an  atom  in  immensity,  is  immensity 
itself  in  its  revelations  of  truth;  and  science,  though  gathered  from  one 
small  sphere,  is  the  deciphered  law  of  all  spheres. 

It  is  well  to  have  the  mind  deeply  imbued  with  this  thought,  before 
entering  upon  the  study  of  the  earth.  It  gives  grandeur  to  science  and 
dignity  to  man,  and  will  help  the  geologist  to  apprehend  the  loftier  charac- 
teristics of  the  last  of  the  geological  ages. 

Special  aim  of  geology,  and  method  of  geological  reasoning.  —  Geology  is 
sometimes  defined  as  the  science  of  the  structure  of  the  earth.  But  the 
ideas  of  structure  and  origin  of  structure  are  inseparably  connected,  and  in 
all  geological  investigations  they  go  together.  Geology  had  its  very  begin- 
ning and  essence  in  the  idea  that  rocks  were  made  through  secondary 
causes ;  and  its  great  aim  has  ever  been  to  study  structure  in  order  to  com- 


12  INTRODUCTION. 

prehend  the  earth's  history.  The  science,  therefore,  is  a  historical  science. 
It  finds  strata  of  sandstone,  clayey  rocks,  and  limestone,  lying  above  one 
another  in  many  successions;  and,  observing  them  in  their  order,  it  assumes, 
not  only  that  the  sandstones  were  made  of  sand  by  some  slow  process, 
clayey  rocks  of  clay,  and  so  on,  but  that  the  strata  were  successively  formed; 
that,  therefore,  they  belong  to  successive  periods  in  the  earth's  past ;  that,  con- 
sequently, the  lowest  beds  in  a  series  were  the  earliest  beds.  It  hence  infers, 
further,  that  each  rock  indicates  some  facts  respecting  the  condition  of  the 
sea  or  land  at  the  time  when  it  was  formed,  one  condition  originating  sand 
deposits,  another  clay  deposits,  another  lime,  —  and,  if  the  beds  extend  over 
thousands  of  square  miles,  that  the  several  conditions  prevailed  uniformly 
to  at  least  this  same  extent.  The  rocks  are  thus  regarded  as  records  of 
successive  events  in  the  history,  —  indeed,  as  actual  historical  records ;  and 
every  new  fact  ascertained  by  a  close  study  of  their  structure,  be  it  but  the 
occurrence  of  a  pebble,  or  a  seam  of  coal,  or  a  bed  of  ore,  or  a  crack,  or 
any  marking  whatever,  is  an  addition  to  the  records,  to  be  interpreted  by 
•careful  study. 

Thus  every  rock  marks  an  epoch  in  the  history ;  and  groups  of  rocks, 
periods ;  and  still  larger  groups,  eras  or  ages ;  and  so  the  eras  which  reach 
through  geological  time  are  represented  in  order  by  the  rocks  that  extend 
from  the  lowest  to  the  uppermost  of  the  series. 

If,  now,  the  great  beds  of  rock,  instead  of  lying  in  even  horizontal 
layers,  are  much  folded  up,  or  lie  inclined  at  various  angles,  or  are  broken 
and  dislocated  through  hundreds  or  thousands  of  feet  in  depth,  or  are 
uplifted  into  mountains,  they  bear  record  of  still  other  events  in  the  great 
history ;  and  should  the  geologist,  by  careful  study,  learn  how  the  great 
disturbance  or  uplifting  was  produced,  and  succeed  in  locating  its  time  of 
occurrence  among  the  epochs  registered  in  the  rocks,  he  would  have  inter- 
preted the  record,  and  added  not  only  a  fact  to  the  history,  but  also  its 
explanation.  The  history  is,  hence,  a  history  of  the  upturnings  of  the 
earth's  crust,  as  well  as  of  its  more  quiet  rock-making. 

If,  in  addition,  a  fossil  shell,  or  coral,  or  bone,  or  leaf,  is  found  in  one  of 
the  beds,  it  is  a  relic  of  some  species  that  lived  when  that  rock  was  forming ; 
it  belongs  to  that  epoch  in  the  world  represented  by  the  particular  rock 
containing  it,  and  tells  of  the  life  of  that  epoch ;  and,  if  numbers  of  such 
organic  remains  occur  together,  they  enable  us  to  people  the  seas  or  land,  to 
our  imagination,  with  some  of  the  kinds  of  life  that  belonged  to  the  ancient 
epoch. 

Moreover,  as  such  fossils  are  common  in  a  large  number  of  the  strata, 
from  the  lowest  containing  signs  of  life  to  the  top, — that  is,  from  the  oldest 
beds  to  the  most  recent,  —  by  studying  out  the  characters  of  these  remains 
in  each,  we  are  enabled  to  restore  to  our  minds,  to  some  extent,  the  popula- 
tion of  the  epochs,  as  they  follow  one  another  in  the  long  series.  The  strata 
are  thus  not  simply  records  of  moving  seas,  sands,  clays,  and  pebbles,  and 
disturbed  or  uplifted  strata,  but  also  of  the  living  beings  that  have  in 


INTRODUCTION.  13 

succession  occupied  the  land  and  waters.  The  history  is  a  history  as  com- 
plete as  can  be  learned  from  the  fossils  of  the  life  of  the  globe,  as  well 
as  of  its  rock-formations ;  and  the  life-history,  imperfect  though  it  be,  is 
the  great  topic  of  Geology :  it  adds  tenfold  interest  to  the  other  records  of 
the  rocks. 

These  examples  are  sufficient  to  explain  the  basis  and  general  bearing  of 
geological  history. 

The  method  of  interpreting  the  records  rests  upon  the  simple  principle 
that  rocks  were  made  as  they  are  now  made,  and  life  lived  in  olden  time  as 
it  now  lives ;  and,  further,  the  mind  is  forced  into  receiving  the  conclusions 
arrived  at  by  its  own  laws  of  action.  We  observe  that  many  of  the  common 
rock-strata  consist  of  the  same  materials  that  make  up  the  deposits  of  sand 
and  gravel  of  sea-beaches  or  sand-flats,  or  of  the  clays  or  muds  of  the  bottoms- 
of  estuaries  or  the  borders  of  rivers,  and  that  they  are  arranged  in  beds  like 
the  modern  deposits,  even  have,  at  times,  ripple-marks  and  other  evidences 
of  the  action  of  water  or  wind ;  and  further  remark  that  these  hard  rocks 
differ  from  the  loose  sand,  clay,  or  pebbly  deposits  simply  in  being  consoli- 
dated into  a  rock;  and,  in  other  places,  discover  these  sand-deposits  in  all 
states  of  consolidation,  from  the  soft,  movable  sand,  through  a  half-compacted 
condition,  to  the  gritty  sandstone.  By  such  steps  as  these,  the  mind  is 
borne  along  irresistibly  to  the  conclusion  that  rocks  were  slowly  made 
through  common-place  operations. 

These  few  examples  elucidate  the  mode  of  reasoning  upon  which  geo- 
logical deductions  are  based. 

In  using  the  present  in  order  to  reveal  the  past,  we  assume  that  the 
forces  in  the  world  are  essentially  the  same  through  all  time;  for  these 
forces  are  based  on  the  very  nature  of  matter,  and  could  not  have  changed. 
The  ocean  has  always  had  its  waves,  and  those  waves  have  ever  acted  in 
the  same  manner.  Running  water  on  the  land  has  ever  had  the  same  power 
of  wear  and  transportation  and  mathematical  value  to  its  force.  The- 
laws  of  chemistry,  heat,  electricity,  and  mechanics  have  been  the  same 
throughout  time.  The  plan  of  living  structures  is  fundamentally  one,  for 
the  whole  series  belongs  to  one  system,  as  much  almost  as  the  parts  of  ani 
animal  to  one  body ;  and  the  relations  of  life  to  light  and  heat,  and  to  the 
atmosphere,  have  ever  been  the  same  as  now.  The  laws  of  the  existing: 
world,  if  perfectly  known,  are  consequently  a  key  to  past  history. 

SUBDIVISIONS  OF   GEOLOGY. 

(1)  Like  a  plant  or  animal,  the  earth  has  its  systematic  external  form 
and  features,  which  should  be  reviewed. 

(2)  Next,  there  are  the  constituents  of  the  structure  to  be  considered: 
first,  their  nature;  second,  their  general  arrangement. 

(3)  Next,  the  successive  stages  in  the  formation  of  the  structure,  and 
the  concurrent  steps  in  the  progress  of  life,  through  past  time. 


14  INTRODUCTION. 

(4)  Next,  the  general  plan  or  laws  of  progress  in  the  earth  and  its  life.  , 

(5)  Finally,  there  are  the  active  forces  and  mechanical  agencies  which 
were  the  means  of  physical   progress,  —  spreading   out   and   consolidating 
strata,  raising  mountains,  ejecting  lavas,  wearing  out  valleys,  bearing  the 
material   of  the  heights  to  the   plains  and  oceans,  enlarging  the  oceans, 
destroying  life,  and  performing  an  efficient  part  in  evolving  the   earth's 
structure  and  features. 

These  topics  lead  to  the  following  subdivisions  of  the  science :  — 

I.  PHYSIOGRAPHIC  GEOLOGY,  —  a  general  survey  of  the  earth's  surface- 
features. 

II.  STRUCTURAL  GEOLOGY,  —  a  description  of  the  rock-materials  in  the 
structure  of  the  globe,  —  that  is,  of  its  kinds  of  rocks,  and  of  their  arrange- 
ment or  positions. 

III.  DYNAMICAL  GEOLOGY,  —  an  account  of  the  agencies  or  forces  that 
have  produced  geological  changes,  and  of  the  laws,  methods,  and  results  of 
their  action. 

IV.  HISTORICAL  GEOLOGY,  —  an  account  of  the   earth's  geological  his- 
tory, or  the  successive  events  or  steps  in  the  making  of  the  rock-strata,  and 
of  the   continents,  seas,  mountains,  and  valleys,    in  the  progress   of  the 
earth's  living  species,  and  in  all  changes  that  have  gone  forward  in  the 
earth's  development. 

In  the  study  of  the  science,  a  previous  knowledge  of  the  methods  of  change  taught  in 
the  Dynamical  section  is  desirable  in  order  fully  to  comprehend  Historical  geology  ;  and 
a  knowledge  of  the  actual  facts  and  their  succession  given  in  the  Historical  section  is 
desirable  to  understand  the  causes  of  events  and  methods  of  change.  There  is  reason, 
therefore,  for  studying  Dynamical  geology  before  Historical  as  well  as  after  it.  It  is  here 
made  to  precede.  But  the  last  topic  under  it  — that  of  the  formation  of  mountains  —  will 
be  best  appreciated  after  the  student  is  familiar  with  the  facts  presented  in  the  Historical 
-section. 


PART  I. 


PHYSIOGRAPHIC   GEOLOGY. 

THE  systematic  arrangement  in  the  earth's  features  is  an  indication 
of  system  in  the  earth's  development.  The  orderly  arrangement  in  the 
continents  and  oceans,  island  chains  and  mountains,  is  an  outcome  of  the 
most  fundamental  movements  in  the  forming  sphere.  An  appreciation 
of  tne  earth's  physiognomy  is  hence  the  first  step  toward  an  investigation 
of  its  laws  of  origin.  This  subject  is  therefore  an  important  one  to  the 
geologist,  although  its  facts  come  also  within  the  domain  of  physical 
geography.  They  are  the  final  results  in  geology,  and  thence  become  the 
arena  of  the  physical  geographer. 

The  following  are  the  divisions  in  this  department :  — 

I.    The  earth's  general  contour  and  surface  subdivisions. 
II.    System  in  the  reliefs  or  surface  forms  of  the  continental  lands. 

III.  System  in  the  courses  of  the  earth's  feature  lines. 

These  topics  are  followed  by  a  brief  review  of,  — 

IV.  Oceanic  and  atmospheric  movements  and  temperature. 
V.   Geographical  distribution  of  plants  and  animals. 

I.  THE  EARTH'S  GENERAL  CONTOUR  AND  SURFACE  SUBDIVISIONS. 

The  subjects  under  this  head  are — the  earth's  form;  the  distribution 
of  land  and  water ;  the  true  outlines  and  features  of  the  oceanic  depression ; 
the  subdivisions,  positions,  and  general  features  of  the  land ;  the  height  and 
kinds  of  surface  of  the  continents. 

(1)  Spheroidal  form.  —  The  form  of  the  earth  is  spherical,  with  the 
poles  flattened,  the  distance  from  the  center  to  the  pole  being  about  ^J^- 
shorter  than  that  from  the  center  to  the  equator.  The  length  of  the 
equatorial  radius  is  3963  miles,  and  that  of  the  polar  about  13^  miles  less. 
The  form  approaches  closely  that  of  an  ellipsoid  of  revolution.  The  mean 
density  is  about  5-5  times  that  of  water,  which  is  a  little  more  than  twice 
that  of  the  two  most  common  minerals,  calcite  (2-72)  and  quartz  (2-65),  and 
more  than  two  thirds  that  of  pure  iron  (7-75). 

15 


16 


PHYSIOGRAPHIC    GEOLOGY. 


The  density  of  the  moon  is  3-1,  or  about  that  of  basalt ;  of  Mercury,  6-2 ;  of  Venus 
and  Mars,  each.  5'2  ;  of  Jupiter,  1-3. 

The  earth's  atmosphere,  if  considered  a  part  of  the  sphere,  adds  several 
hundred  miles  to  its  diameter.  Its  actual  limit  is  not  ascertained  j  but  evi- 
dence from  meteorites  places  it  at  least  200  miles  above  the  earth's  surface. 

(2)  General  subdivisions  of  the  earth's  surface. — Proportion  of  land  and 
water. — In  the  surface  of  the  sphere  there  are  about  73%  of  water  to  27% 
of  dry  land.  The  proportion  of  land  north  of  the  equator  is  nearly  three 
times  as  great  as  that  south.  The  zone  containing  the  largest  proportion 
of  land  is  the  north  temperate,  the  area  equaling  that  of  the  water ;  while 
it  is  only  one  third  that  of  the  water  in  the  torrid  zone,  and  hardly  one 
tenth  (^)  in  the  south  temperate. 

Out  of  the  196,900,000  of  square  miles  which  make  up  the  entire 
surface  of  the  globe,  144,155,000  are  water  and  52,745,000  land.  In  the 
northern  hemisphere  the  land  covers  38,780,000  square  miles,  and  the  water 
59,670,000;  in  the  southern,  the  land  13,965,000  square  miles,  the  water 
84,485,000. 

Land  in  one  hemisphere.  —  If  a  globe  be  cut  through  the  center  by  a 
plane  intersecting  the  meridian  of  175°  E.  at  the  parallel  of  40°  N.,  one  of 
the  hemispheres  thus  made,  the  northern,  will  contain  nearly  all  the  land  of 
the  globe,  and  the  other  be  almost  wholly  water.  The  annexed  map  repre- 
sents the  two  hemispheres. 


1. 


16JLJJL2-165 


The  pole  of  the  land-hemisphere  in  this  map  is  in  the  western  half  of 
the  British  Channel ;  and,  if  this  part,  on  a  common  globe,  be  placed  in  the 
zenith,  under  the  brass  meridian,  the  horizon-circle  will  then  mark  the  line 
of  division  between  the  two  hemispheres.  Of  the  98,450,000  square  miles 
of  surface  in  each  hemisphere,  there  are  about  45,000,000  of  land  in  the 
land-hemisphere  and  only  about  7,000,000  in  the  other.  The  portions  of 
land  in  the  water-hemisphere  are  the  extremity  of  South  America  below 


THE  EARTH'S  CONTOUR  AND  SURFACE  SUBDIVISIONS.  IT 

25°  S.,  and  Australia,  together  with  the  islands  of  the  East  Indies,  the  Pacific, 
a.nd  the  Antarctic.  London  and  Paris  are  situated  very  near  the  center  of 
the  land-hemisphere. 

General  arrangement  of  the  oceans  and  continents.  —  Oceans  and  conti- 
nents are  the  grander  divisions  of  the  earth's  surface.  But,  while  the 
continents  are  separate  areas,  the  oceans  occupy  one  continuous  basin  or 
channel.  The  waters  surround  the  Antarctic  pole  and  stretch  north  in  three 
prolongations,  —  the  Atlantic,  the  Pacific,  and  the  Indian  oceans.  The  land 
is  gathered  about  the  Arctic,  and  reaches  south  in  two  great  continental 
masses,  the  occidental  and  oriental,  called  America  and  Eurasia;  but  the 
latter,  through  Africa  and  Australia,  has  two  southern  prolongations, 
making,  in  all,  three,  corresponding  to  the  three  oceans.  Thus  the  conti- 
nents and  oceans  interlock,  the  former  narrowing  southward,  the  latter 
northward. 

This  subject  is  illustrated  on  the  map,  page  47.  It  is  a  Mercator's  chart  of  the  World, 
which,  while  it  exaggerates  the  polar  regions,  has  the  great  advantage  of  giving  correctly 
all  courses,  that  is,  the  bearings  of  places  and  coasts.  The  trends  of  lines  ("  trend  "  means 
merely  course  or  bearing)  admit,  therefore,  of  direct  comparison  upon  such  a  chart.  It  is 
important  that  the  globe  should  be  carefully  studied  in  connection  with  it,  in  order  to 
correct  misapprehensions  as  to  distances  in  the  higher  latitudes,  and  to  appreciate  the 
convergences  between  lines  that  have  the  same  compass-course.  The  low  lands  of  the 
continents  on  this  chart,  or  those  below  800  feet  in  elevation  above  the  sea,  are  distin- 
guished from  the  higher  lands  and  plateaus  by  a  lighter  shading.  The  oceans  are  crossed 
by  isothermal  lines,  which  are  explained  beyond. 

The  Atlantic  is  the  narrow  ocean,  the  mean  breadth  of  the  North  Atlantic 
being  about  2800  miles.  The  Pacific  is  the  broad  ocean,  being  6000  miles 
across,  or  more  than  twice  the  breadth  of  the  Atlantic.  The  Occident,  or 
America,  is  the  narrow  continent,  about  2200  miles  in  average  breadth ; 
Eurasia,  the  broad  continent,  6000  miles  in  average  breadth.  Each  continent 
has,  therefore,  as  regards  size,  its  representative  ocean.  The  Pacific  Ocean, 
reckoning  only  to  62°  S.,  has  an  area  of  62,000,000  square  miles.  This  is  ten 
millions  beyond  the  area  of  the  continents  and  islands,  and  nearly  one  third 
of  the  earth's  surface. 

(3)  Oceanic  depression.  —  (a)  Outline.  —  The  oceanic  depression  is  a  vast 
sunken  area,  varying  in  depth  from  500  feet  or  less  to  probably  30,000  feet. 

The  true  outline  of  the  depression  is  not  necessarily  the  present  coast- 
line. About  the  continents  there  is  often  a  shallow  region  which  is  the 
submerged  border  of  the  continent.  On  the  North  American  coast,  off  New 
Jersey,  as  shown  on  the  bathymetric  map  (page  18),  this  submerged  border 
extends  out  for  110  miles  (and  120  from  New  York  City),  with  a  depth, 
at  this  distance,  of  only  600  feet,  its  slope  outward  only  one  foot  in  968. 
At  the  1.00-fathom  line,  as  shown  on  the  map,  the  waters  suddenly  deepen, 
and  here  the  true  oceanic  basin  begins.  This  continental  border  of  the 
ocean  (see  large  bathymetric  map  following  page  20,  on  which  the  100-fathom 
line  is  finely  dotted)  extends  northward  to  Newfoundland  and  beyond,  and 
DANA'S  MANUAL,  —  2 


18 


PHYSIOGRAPHIC   GEOLOGY. 


also  southward  to  Cape  Hatteras.  Off  the  Carolinas  it  narrows  much ;  but 
in  the  Gulf  of  Mexico  it  has  its  usual  width.  At  times  in  geological  history 
it  has  been  part  of  the  actual  dry  border  of  the  continent.  This  is  proved 
by  the  existence  of  a  river-channel,  that  of  the  Hudson,  over  its  submerged 
surface,  as  shown  on  the  accompanying  map  of  the  Atlantic  border.  As 
here  seen,  the  depth. of  water  over  this  border  is  not  50  fathoms  (300  feet) 
until  within  15  miles  of  the  100-fathoin  line. 


74M 
Long  Island  Sound,  jf| 

Long  Island, 

and  the 

Atlantic  Border 

with 

Depths  along  Bathymetrio 
lines  in  fathoms ; 
lines  in  Long  Island  Sound 
'the  under-water  Channel 
it  Hudson  River,  from 
Coast  Survey  Charts. 


72:00 


»    SCALE  OF'Mll-ES 
J>     10          20  30          40  ^0 60          70 


400 


Map  of  the  Atlantic  border. 

On  the  Pacific  side  of  both  North  and  South  America  the  submerged 
continental  border  is  narrow.  Off  California,  the  distance  to  the  100-fathom 
line  is  in  general  only  about  10  miles.  There  is  then  a  sharp  descent  to 
500  or  600  fathoms,  and  from  this  a  decline  of  1600  to  2400  fathoms  within 
40  or  50  miles.  This  is  in  great  contrast  with  the  Atlantic  border.  G. 
Davidson,  of  the  Coast  Survey,  reports  the  existence  of  several  deep 
submarine  channels  leading  outward  from  the  coast,  which  are  most  proba- 
bly due  to  streams  that  flowed  along  them  at  some  time  when  the  land 
stood  much  above  its  present  level. 


THE  EARTH'S  CONTOUR  AND  SURFACE  SUBDIVISIONS.          19 

Great  Britain  stands  on  a  broad  continental  border  not  over  600  feet 
deep,  and  is  therefore  part  of  the  European  continent.  A  large  part  of  the 
German  Ocean  is  not  over  95  feet  deep. 

In  a  similar  manner,  the  East  India  Islands  down  to  a  line  by  the  north 
of  New  Guinea  and  Celebes  are  a  part  of  Asia,  the  depth  of  the  seas  between 
seldom  exceeding  300  feet,  while  New  Guinea  is  a  part  of  Australia.  In  like 
manner,  the  Falkland  Islands  are  a  part  of  South  America. 

These  facts  with  respect  to  the  100-fathom  .(600  feet)  limit  off  the 
American  and  other  coasts  are  illustrated  on  the  following  map. 

(6)  Depths  of  the  ocean.  —  The  depths  of  the  ocean  are  given  on  the 
following  bathymetric  map,  prepared  by  the  author  from  the  charts  of 
the  United  States  and  British  Hydrographic  Department,  and  from  the 
soundings  of  the  vessels  of  the  United  States  Fish  Commission.  The  lines 
marking  equal  depths  are  made  heaviest  for  the  greatest  depths,  as  explained 
on  the  map.  The  depths  are  given  in  100  fathoms,  21  meaning  2100 
fathoms  (12,600  feet). 

The  mean  depth  of  the  whole  ocean  has  been  estimated  at  14,000  feet ; 
that  of  the  North  Atlantic,  at  15,000 ;  and  that  of  the  North  Pacific,  at  16,000 
feet.  As  exhibited  on  the  map,  the  western  half  of  the  Pacific  and  Atlantic 
oceans  has  greater  mean  depth  than  the  eastern;  for  it  contains  all  the 
4000-fathom  areas,  and  the  larger  part  of  the  3000-fathom  areas.  In  the 
Indian  Ocean  the  eastern  side  is  the  deeper. 

In  the  North  Atlantic,  deep  waters  and  abrupt  slopes  extend  along  near 
the  north  shores  of  the  West  India  Islands  ;  and  in  this  line,  north  of  Puerto 
Eico,  occurs  the  greatest  depth  of  the  Atlantic  Ocean,  4561  fathoms,  or 
27,366  feet.  The  mean  slope  from  the  Puerto  Eico  coast  to  the  bottom  is 
about  1 : 14.  A  deep  trough  with  abrupt  sides  extends  from  this  depression 
westward,  north  of  Haiti  or  San  Domingo ;  and  south  of  Cuba  there  are 
depths  between  18,000  and  21,000  feet. 

In  the  Pacific,  off  the  east  shore  of  northern  Japan  and  the  Kurile 
Islands,  there  is  a  long  4000-fathoui  area,  in  which  the  greatest  depth  found 
is  4656  fathoms,  or  27,936  feet.  An  isolated  depression  of  4475  exists  south 
of  the  largest  end  of  the  Ladrone  Islands,  and  others  over  4000  fathoms 
southeast  of  the  Friendly  Islands. 

In  the  North  Atlantic,  between  Greenland  and  Iceland  and  Norway,  the 
great  Scandinavian  plateau  lies  at  a  depth,  in  general,  of  only  1500  to  3000 
feet;  and  along  one  course  the  greatest  depth  does  not  exceed  3600  feet. 
Iceland  stands  upon  it  and  is  prolonged  in  a  ridge  under  water  southwest- 
ward  for  750  miles,  and  northeastward  to  the  island  of  Jan  Mayen.  The 
plateau  has  to  the  north  of  it  a  large,  deep  region  of  12,000  to  15,000  feet. 
To  the  southward  it  is  prolonged  southwestward  in  a  relatively  shallow  area, 
called  the  Dolphin  shoal,  which  passes  near  the  middle  of  the  ocean  to  the 
parallel  of  25°  N.  or  beyond,  with  less  than  12,000  feet  of  water  over  it,  and 
mostly  under  9600  feet.  Either  side,  the  depths  are  15,000  feet  or  over,  and 


20  PHYSIOGRAPHIC   GEOLOGY. 

to  the  westward,  to  a  large  extent,  17,400  to  21,000  feet.  The  facts  show 
plainly  that  if  this  Dolphin  shoal  was  ever  emerged  as  an  Atlantic  conti- 
nent, —  the  fabled  Atlantis  of  speculation,  —  it  never  could  have  contributed 
any  of  its  detritus  to  the  American  continent.  It  belongs  more  to  the 
European  side. 

Another  shallow  area  occupies  the  middle  of  the  south  Atlantic  basin  in  a  nOrth-and- 
south  direction  •  and  at  its  north  end  it  is  prolonged  west-northwestward  toward  shallow 
areas  farther  west.  Whether  the  shallow  area  about  its  southern  extremity  reaches  into 
antarctic  seas  is  not  yet  ascertained.  A  large  shallow  area  exists  on  both  sides  of  Pata- 
gonia, with  a  west-northwest  trend  (see  map).  It  may  be  continued  in  the  Pacific  to  the 
Paumotus  and  beyond  ;  if  so,  it  follows  the  course  nearly  of  the  axis  of  the  Pacific  Ocean, 
as  the  Dolphin  shoal  does  that  of  the  North  Atlantic. 

The  West  India  sea  has  three  deep  areas :  that  of  the  Caribbean  Sea,  17,000  feet  in 
greatest  depth  (which  has  its  deepest  connection  with  the  Atlantic  between  Santa  Cruz 
and  Puerto  Rico,  5400  feet)  ;  the  Cuban  sea,  or  west  Caribbean,  separated  from  the  east 
Caribbean  by  shallow  waters  — 600  to  4080  feet  (100  to  680  fathoms)  —between  Honduras 
and  Jamaica,  with  a  maximum  depth  of  more  than  20,000  feet ;  and  the  Gulf  of  Mexico, 
12,714  feet  in  maximum  depth.  The  Mediterranean  Sea,  2100  miles  long,  has  likewise 
its  three  deep-water  areas:  the  eastern  or  "Levant"  sea,  about  13,000  feet  in  greatest 
depth ;  the  central,  between  Sardinia  and  Italy  (separated  from  the  eastern  by  relatively 
shallow  water,  not  ever  200  fathoms,  between  western  Sicily  and  Tunis,  in  Africa),  12,500 
feet ;  and  the  western,  9500  feet. 

The  Straits  of  Gibraltar  are  mostly  about  900  fathoms  deep,  but  only  160  between 
Cape  Spartel  and  Cape  Trafalgar. 

The  ranges  of  islands  show  the  chief  courses  of  shallow  water  in  the 
ocean,  and  the  bathymetric  lines  drawn  about  them,  the  outline  of  the 
basement  ridges,  of  which  the  islands  are  the  summits.  Some  of  the  isolated 
islands,  especially  those  of  coral-reef  origin,  have  great  depths  close  about 
them.  Bermuda,  in  the  Atlantic,  has  a  depth  of  nearly  16,000  feet  (2650 
fathoms)  within  25  miles  to  the  eastward,  whence  the  mean  submarine 
slope  is  1:8^;  and  a  depth  of  12,000  feet  exists  within  six  miles  on  one 
side  and  9J  miles  on  the  opposite  —  making  the  mean  submarine  slopes  to 
this  depth  very  steep,  they  being  i :  2'64  and  1 : 4-2.  The  small  Phoenix 
Islands,  in  the  central  Pacific,  stand  in  a  large  area  of  18,000  to  21,000  feet, 
and  have  depths  of  18,000  to  20,000  feet  between  them,  with  similarly 
steep  submarine  slopes ;  in  one  case  a  slope  to  the  12,000  point  of  1 :  1*5. 
At  Keeling  atoll,  in  the  Paumotu  Archipelago,  Captain  Fitzroy,  R.  N.,  found 
no  bottom  in  7200  feet  at  2200  yards  from  the  breakers  —  which  gives  a 
pitch-off  exceeding  1 :  0-92. 

The  island  chains  of  the  ocean  may  seem  to  indicate  that  great  irregu- 
larity prevails  elsewhere  over  the  bottom  of  the  ocean.  But,  while  abrupt 
depressions  and  elevations  do  exist,  the  abyssal  slopes  are  in  general  very 
gradual.  One  remarkable  exception  is  the  occurrence  in  the  vicinity  of  the 
Canaries  of  a  submarine  crater  a  few  miles  wide  and  1000  feet  deep.  Such 
cases  are  most  likely  to  occur  in  the  vicinity  of  volcanic  islands.  Whether 
the  great  depths  south  of  the  Ladrones  and  the  Friendly  Islands  are  craters 
or  not  is  undetermined. 


A  U  S      Rvl 


N.S.WAUSV 


BATHYMETKIC 


PACIFIC  AND  ATLANTIC 

OCEANS. 


THE  EARTH'S  CONTOUR  AND  SURFACE  SUBDIVISIONS.  21 

To  appreciate  the  oceanic  basins,  we  must  conceive  of  the  earth  without 
water,  —  the  depressed  areas,  thousands  of  miles  across,  sunk  10,000  to 
perhaps  30,000  feet  below  the  bordering  continental  regions,  and  covering 
four  elevenths  of  the  whole  surface.  The  continents,  in  such  a  condition, 
would  stand  as  elevated  mountain  plateaus  encircled  by  one  great  uneven, 
almost  featureless,  basin.  If  the  earth  had  been  left  thus,  with  but  shallow 
briny  lakes  about  the  bottom,  there  would  have  been  an  ascent  of  five 
miles  or  more  from  the  Atlantic  basin  to  the  lower  part  of  the  continen- 
tal plateau,  and  about  five  miles  more  to  scale  the  summits  of  the  loftier 
mountains  of  the  globe.  The  continents  would  have  been  wholly  in  the 
regions  of  the  upper  cold,  all  alpine,  and  the  bottoms  of  the  oceanic 
basin  under  oppressive  heat,  with  drought  and  barrenness  universal.  The 
uneven  surface  of  the  oceanic  basin  has  been  leveled  off  to  a  plain  by 
filling  it  with  water.  The  greatest  heights  of  the  world  have  thereby  been 
diminished  more  than  one  half,  and  genial  climates  substituted  for  intol- 
erable extremes,  rendering  nearly  all  the  emerged  land  habitable,  and  giving 
moisture  for  clouds,  rivers,  and  living  species.  By  the  same  means  distant 
countries  have  been  bound  together  by  a  common  highway,  into  one  arena 
of  history. 

The  calculated  mass  of  the  ocean,  taking  the  depth  as  above  given,  is 
1,320,000,000,000,000,000  tons. 

(4)  General  view  of  the  land.  —  (a)  Position  of  the  land.. —  The  land. of 
the  globe  has  been  stated  to  lie  with  its  mass  to  the  north,  about  the  Arctic 
pole,  and  to  narrow  as  it  extends  southward  into  the  waters  of  the  southern 
hemisphere ;  with  the  mean  southern  limit  of  the  continental  lands  in  the 
parallel  of  45°,  or  just  half-way  from  the  equator  to  the  south  pole. 

South  America  reaches  to  56°  S.  (Cape  Horn  being  in  55°  58'),  which 
is  the  latitude  of  Edinburgh  or  northern  Labrador;  Africa  only  to  34°  51' 
(Cape  of  Good  Hope),  nearly  the  latitude  of  the  southern  boundary  of 
Tennessee,  and  60  miles  nearer  the  equator  than  Gibraltar ;  Tasmania  (Van 
Diemen's  Land)  to  43^-°  S.,  nearly  the  latitude  of  Boston  or  northern 
Portugal. 

(b)  Distribution.  —  The  independent  continental  areas  are  three  in  num- 
ber :  America,  one  ;  Europe,  Asia,  or  Eurasia,  and  Africa,  a  second ;  Australia, 
the  third.  Through  the  East  India  Islands,  Australia  is  approximately  con- 
nected with  Asia,  nearly  as  South  America  with  North  America  through 
the  West  Indies  ;  and,  regarding  it  as  thus  united,  the  great  masses  of  land 
will  be  but  two, — the  American,  or  Occidental,  and  Europe,  Asia,  Africa, 
and  Australia,  or  the  Oriental. 

But,  further,  these  great  masses  of  land  are  divided  across  from  east  to 
west  by  seas  or  archipelagoes.  The  West  Indies  (between  the  parallels  of 
10°  N.  and  30°  K),  the  Mediterranean  (between  30°  K  and  45°  N.),  and  the 
Bed  Sea,  and  the  East  Indies  (between  30°  N.  and  10°  S.),  with  the  connect- 
ing oceans,  make  a  nearly  complete  band  of  water  around  the  globe,  sub- 


22  PHYSIOGRAPHIC    GEOLOGY. 

dividing  the  Occident  and  Orient  into  north  and  south  divisions.  Cutting 
across  37  miles  at  the  Isthmus  of  Darien,  where  at  the  lowest  pass  the 
greatest  height  above  mean  tide  level  does  not  exceed  260  feet,  as  has  been 
done  at  the  Isthmus  of  Suez,  where  the  highest  point  of  the  isthmus  is  only 
40  feet  above  the  sea,  the  girth  of  water  would  be  unbroken.  This  belt  of 
water,  like  the  continents,  is  situated  mostly  in  the  northern  hemisphere, 
instead  of  corresponding  in  its  course  to  any  great  circle. 

America  is  thus  divided  into  North  and  South  America.  The  oriental 
lands  have  one  great  area  on  the  north,  comprising  Europe  and  Asia  com- 
bined, often  named  Eurasia,  and,  on  the  south,  (1)  Africa,  separated  from 
Europe  by  the  Mediterranean,  and  (2)  Australia,  separated  from  Asia 
by  the  East  India  seas.  Thus  the  narrow  Occident  has  one  southern 
prolongation,  and  the  wide  Orient  two.  The  Orient  is  thus  equivalent  to 
two  Occidents  in  which  the  northern  areas  coalesce,  —  Europe  and  Africa 
one,  Asia  and  Australia  the  other ;  so  that  there  are  really  three  doublets  in 
the  system  of  continental  lands.  The  Caspian  and  Aral,  which  are  salt  seas, 
lie  in  a  depression  of  the  continent  of  great  extent,  —  the  Aral  being  near 
the  level  of  the  ocean,  and  the  Caspian  84  feet  below  that  of  the  Black  Sea. 

The  continents  have  several  Common  features  entitling  them  to  be  viewed 
as  individuals  under  a  common  type  of  structure.  They  have  (1)  a  like 
position  on  the  sphere,  each  lying  with  its  head  or  broader  end  to  the  north, 
and  the  tapering  extremity  to  the  south.  North  America,  South  America, 
and  Africa  strongly  exhibit  this  characteristic  ;  Asia  somewhat  less  mani- 
festly, yet  decidedly  in  the  great  triangles  of  her  southern  border,  Hindostan 
and  Siam.  Australia  is  seemingly  an  exception ;  but  there  is  evidence  that 
this  land  has  been  narrowed  and  shortened  by  subsidence,  and  thus  has  lost 
New  Zealand,  its  eastern  front,  and  probably  a  large  region  to  the  south. 
(See  large  bathymetric  map  following  page  20.) 

Another  striking  fact,  showing  system  in  arrangement,  is  seen  (2)  in  the 
relative  positions  of  the  southern  and  northern  continents.  South  America 
and  Australia  are  not  to  the  south  of  the  related  northern  continent ;  on  the 
contrary,  the  center  of  South  America  is  about  40°  in  longitude  east  of 
that  of  North  America,  or  nearly  an  eighth  of  the  sphere,  and  Australia 
40°  east  of  that  of  Asia.  Thus  there  is  a  zigzag  alternation  in  the  positions 
of  the  four  great  masses  of  land.  Further,  (3)  the  curving  line  of  islands 
in  the  West  Indies  from  Florida  to  Trinidad  is  similar  in  form  to  that 
between  Malacca  through  Sumatra  and  New  Guinea  to  New  Zealand, 
although  much  shorter. 

These  are  three  of  the  points  in  which  the  continental  individualities 
exhibit  the  system  that  exists  in  the  earth's  physiognomy. 

(c)  The  islands.  —  The  islands  adjoining  the  continents  are  properly  conti- 
nental islands.  Besides  the  examples  mentioned  on  page  19,  Japan  and  the 
ranges  of  islands  of  eastern  Asia  are  strictly  a  part  of  Asia,  for  they  con- 
form in  direction  to  the  Asiatic  system  of  heights,  and  are  united  to  the 


THE  EARTH'S  CONTOUK  AND  SURFACE  SUBDIVISIONS.  23 

main  by  shallow  waters.  Vancouver  Island  and  others  north  of  it  are 
similarly  a  part  of  North  America ;  Chiloe,  and  the  islands  south  to  Cape 
Horn,  a  part  of  South  America;  and  so  in  other  cases.  In  general  they 
correspond  to  a  broader  mountain  range  more  or  less  submerged. 

The  oceanic  islands  are,  in  general,  as  has  been  stated,  the  summits  of 
submerged  oceanic  mountain  chains.  The  Atlantic  arid  Indian  oceans  are 
mostly  free  from  them.  The  Pacific  contains  about  675  islands,  with  a  mean 
area  of  only  80,000  square  miles.  Excluding  New  Caledonia  and  some  other 
large  islands  in  its  southeastern  part,  the  remaining  600  islands  have  an  area 
of  but  40,000  square  miles,  or  less  than  that  of  the  state  of  New  York. 

(d)  Mean  elevation  of  the  land.  —  The  mean  height  of  the  continents 
above  the  sea  has  been  estimated  at  nearly  1800  feet,  and  the  mean  height 
of  them  severally  is  stated  as  follows  :  Europe,  975  feet ;  Asia,  2880 ;  North 
America,  2000 ;  South  America,  1750  ;  and  Africa,  probably  about  2000  feet. 
The  material  of  the  Pyrenees  spread  over  Europe  would  raise  the  surface 
only  6  feet ;  and  the  Alps,  though  of  four  times  larger  area,  only  22  feet. 

The  following  estimates  have  been  made  for  the  mean  heights  of  the  United  States  : 
for  the  whole  area,  Alaska  excluded,  2500  feet ;  Alabama,  500  ;  Arizona,  4100  ;  Arkansas, 
650  ;  California,  2900  ;  Colorado,  6800  ;  Connecticut,  500 ;  Delaware,  60 ;  District  of  Co- 
lumbia, 150  ;  Florida,  100  ;  Georgia,  600  ;  Idaho,  5000  ;  Illinois,  600  ;  Indiana,  700  ;  Iowa, 
1100  ;  Kansas,  2000  ;  Kentucky,  750  ;  Louisiana,  100  ;  Maine,  600  ;  Maryland,  350  ;  Mas- 
sachusetts, 500  ;  Michigan,  900  ;  Minnesota,  1200  ;  Mississippi,  300  ;  Missouri,  800  ;  Mon- 
tana, 3400  ;  Nebraska,  2600  ;  Nevada,  5500  ;  New  Hampshire,  1000  ;  New  Jersey,  250 ; 
New  Mexico,  5700  ;  New  York,  900  ;  North  Carolina,  700  ;  North  Dakota,  1900  ;  Ohio,  850 ; 
Oklahoma,  1300  ;  Oregon,  3300  ;  Pennsylvania,  1100  ;  Rhode  Island,  200  ;  South  Carolina, 
350 ;  South  Dakota,  2200 ;  Tennessee,  900  ;  Texas,  1700 ;  Utah,  6100 ;  Vermont,  1000 ; 
Virginia,  950;  Washington,  1700;  West  Virginia,  1500;  Wisconsin,  1050;  Wyoming, 
6700.  (Gannett.) 

The  extremes  of  level  in  the  land,  so  far  as  now  known,  are,  1390  feet 
below  the  level  of  the  ocean  at  the  Dead  Sea,  1300  feet  in  the  deepest  part 
of  the  Jordan  valley,  and  29,002  feet  high  in  Mount  Everest  of  the  Himalayas, 
which  have  many  peaks  over  25,000  feet. 

In  America,  Death  Valley,  on  the  southeast  border  of  California,  descends 
480  feet  below  the  sea  level.  As  stated  by  F.  S.  Coville,  it  is  175  miles  long 
and  20  in  greatest  width,  and  has  the  Funeral  Mountains,  7000  feet  high,  on 
the  east,  and  the  Panamints,  11,000  feet,  on  the  west. 

(5)  Subdivisions  of  the  surface,  and  character  of  its  reliefs.  —  The  surfaces 
of  continents  are  conveniently  divided  into  (1)  lowlands ;  (2)  plateaus,  or 
elevated  table-lands ;  (3)  mountains.  The  varying  levels  above  the  sea 
make  up  the  reliefs  of  a  continent.  The  limits  between  these  subdivisions 
are  quite  indefinite,  and  are  to  be  determined  from  a  general  survey  of  a 
country  rather  than  from  any  specific  definitions. 

LOWLANDS.  —  The  lowlands  include  the  extended  plains  or  country  lying 
not  far  above  tide  level.  In  general  they  are  less  than  1000  feet  above  the 
sea;  but  they  are  marked  off  rather  by  their  contrast  with  higher  lands  of 


24  PHYSIOGRAPHIC   GEOLOGY. 

the  mountain  regions  than  by  any  special  altitude.  The  surface  is  usually 
undulating,  and  often  hilly.  The  great  interior  region  of  the  North  Ameri- 
can continent,  including  the  Mississippi  valley,  is  an  example  of  an  interior 
plain ;  also  the  plains  of  the  Amazon ;  the  pampas  of  La  Plata ;  the  lower 
lands  of  Europe  and  Asia.  Frequently  the  surface  rises  gradually  into  the 
bordering  mountain-declivities,  as  in  the  case  of  the  Mississippi  plains  and 
the  Eocky  Mountain  slope.  Broad,' low  plains  between  mountain  ranges  and 
the  seashore  are  called  coastal  plains.  Along  the  eastern  border  of  North 
America  from  New  Jersey  southward,  the  coastal  plains  are  broad  and  have 
navigable  streams.  Next  west  is  a  region  of  more  uneven  and  rocky  country 
with  rapid  streams — the  Piedmont  region,  which  extends  to  the  Appalachian 
region,  or  that  of  the  mountains. 

A  mountain  is  either  a  single  peak,  as  Mount  Etna,  Mount  Washington, 
Mount  Blanc  ;  or  a  ridge ;  or  a  series  of  ridges,  sometimes  grouped  in  many, 
more  or  less  parallel,  lines. 

A  mountain  range  consists  of  a  series  of  ridges  closely  related  in  position, 
direction,  and  origin:  as  in  the  Appalachian  ranges,  the  Wasatch,  the 
Sierra  Nevada.  A  sierra  is,  in  Spanish,  the  name  of  a  ridge,  or  group  of 
ridges,  of  serrated  or  irregular  outline. 

A  mountain  system  consists  of  two  or  more  mountain  ranges,  of  the  same 
period  of  origin,  belonging  to  a  common  region  of  elevation,  and  generally 
either  parallel  or  in  consecutive  lines,  or  consecutive  curves,  with  often 
inferior  transverse  lines  of  heights.  A  mountain  chain  consists  of  two  or 
more  mountain-systems  of  different  periods  of  origin,  in  the  same  part  of  a 
continent.  The  oldest  of  the  mountain  ranges  in  a  chain  is  called  the  protaxis 
—  so  named  from  the  Greek  for  first  and  axis  (see  the  map  of  the  Archaean 
areas  on  page  443).  The  other  ranges  are  usually  parallel  to  the  protaxis, 
and  may,  or  may  not,  have  greater  height.  The  Appalachian  Chain  ex- 
tends from  Canada  to  Alabama,  and  comprises  (1)  the  protaxis,  represented 
by  the  Highlands  of  New  Jersey  and  Putnam  County,  New  York,  and  their 
continuation  northward  interruptedly  along  the  eastern  half  of  the  Green 
Mountains  into  Canada,  and  southward,  as  a  narrow,  interrupted  area, 
through  Pennsylvania,  and  a  very  broad  area  through  Virginia,  to  Georgia ; 
(2)  the  Taconic  Eange,  along  the  borders  of  New  England  and  New  York  to 
New  Jersey  and  beyond  ;  and  (3)  the  Appalachian  Eange. 

The  Eocky  Mountains  also  have  a  protaxis,  with  approximately  paral- 
lel ranges  of  later  formation.  This  protaxis  is  the  "  Front  Eange  "  in  Colo- 
rado, nearly  1000  miles  from  the  Pacific  coast,  making  the  Pacific  border 
region  in  this  part  very  wide.  But  to  the  north,  in  Montana  and  Wyoming, 
the  protaxis  makes  a  westward  bend  of  250  miles,  and  then  resumes  a  north- 
westward course  and  continues  to  the  parallel  of  52-J-0,  and  is  represented 
beyond  this  in  isolated  ridges  ;  consequently  the  Pacific  border  region  of 
British  America  is  relatively  narrow.  The  line  to  the  north  of  the  United 
States  appears  to  be  represented  to  the  south  in  the  Archaean  axis  of  the 
Wasatch  and  some  other  similar  ridges.  The  very  large  area  of  the  Pacific 


THE  EARTH'S  CONTOUR  AND  SURFACE  SUBDIVISIONS.  25 

border,  lying  between  the  Wasatch  line  and  the  line  of  the  Front  Eange,  is 
distinctively  a  Rocky  Summit  area,  and  peculiar  to  the  United  States  portion 
of  the  chain.  A  cordillera  is  a  combination  of  mountain  chains. 

The  Coast  Cordillera  within  about  150  miles  of  the  coast  includes  the 
Sierra  Nevada  and  Cascade  ranges  and  a  range  in  continuation  in  British 
Columbia,  which  constitute  together  a  Sierra  Chain,  and  have  heights  equal 
to  those  of  the  Rocky  Mountain  summit,  and  a  Coast  Chain  2000  to  4000 
feet  high  in  California,  which  is  continued  in  the  Vancouver  Eange  of  British 
America,  —  484  feet  high  in  one  Vancouver  peak,  —  and,  beyond  the  islands 
of  the  coast,  in  the  lofty  Fairweather  and  St.  Elias  line  of  heights.  On  the 
terms  range,  system,  chain,  cordillera,  etc.,  see  further,  page  389. 

PLATEAUS. — A  plateau  is  an  extensive  elevated  region  of  flat  or  hilly 
surface,  sometimes  intersected  by  ranges  of  mountains.  Any  extensive  range 
of  generally  flat  country  that  is  over  a  thousand  feet  in  altitude  is  called  a 
plateau.  It  may  lie  along  the  course  of  a  mountain  chain,  or  occupy  a  wide 
region  between  distant  chains.  The  high  land  that  forms  the  southern  half 
of  New  York  is  generally  1500  to  2000  feet  high,  and  reaching  an  elevation  of 
more  than  4000  feet  in  the  Catskills,  is  the  northern  part  of  a  plateau  which 
southward  extends  through  Pennsylvania  to  Tennessee,  and  in  the  latter  re- 
gion constitutes  the  Cumberland  Table-land.  It  is  an  example  of  a  marginal 
plateau,  connected  in  origin  with  a  mountain  range,  —  that  of  the  Appalachian 
Mountains,  —  and  constituting  its  outer  margin.  The  channeling  action  of 
running  water  has  mostly  obliterated  the  plateau  character,  and  converted  the 
region  into  a  group  of  peaks,  ridges,  and  valleys.  In  this  way  high  plateaus 
have  often  been  sculptured  into  mountain-like  forms.  The  "  high  plateaus  " 
of  southern  Utah,  which  range  in  height  from  7000  to  9500  feet,  are  properly 
a  marginal  appendage  to  the  Wasatch  Eange,  as  their  elevation  was  connected 
with  that  attending  the  making  of  these  mountains. 

Other  plateaus  are  intermont  plateaus.  They  occupy  the  interval  between 
mountain  ranges,  chains,  or  cordilleras,  and  are  the  highest  and  largest  of 
plateaus.  Between  the  Eocky  and  Sierra  cordilleras  a  broad  plateau 
extends  from  Mexico  northwestward  through  British  America.  It  is  mostly 
from  3000  to  5000  feet  in  altitude,  but  the  Columbia  Eiver  and  the  Colorado 
have  each  cut  a  way  through  the  Sierra  Chain  and  reduced  the  level  by 
denudation.  There  are  many  high  ridges  in  the  plateau,  parallel  in  course, 
or  nearly  so,  to  the  mountain  ranges  of  the  sides,  and  in  part  of  Oregon  and 
of  British  Columbia  ridges  occupy  the  whole  breadth ;  but  in  general  the 
plateau  features  are  well  defined. 

The  portion  of  the  plateau  between  the  Colorado  and  Columbia  rivers 
is  called  the  Great  Basin.  It  has  the  Great  Salt  Lake  and  the  Wasatch 
Mountains  on  the  east,  and  the  Sierra  Nevada  and  Cascade  Mountains  on 
the  west,  and  in  this  part  it  is  nearly  500  miles  wide.  Its  surface  is  mostly 
4000  to  5000  feet  above  tide  level ;  but  although  so  high,  it  has  no  outside 
drainage.  Its  streams  are  short,  and  dry  up  over  arid  saline  plains  or  end  in 
saline  lakes.  Great  Salt  Lake,  in  Utah,  is  one  of  these  lakes  near  its  eastern 


26  PHYSIOGRAPHIC   GEOLOGY. 

border,  and  Mono  Lake  in  California,  at  the  foot  of  the  lofty  Sierra,  is 
another  on  the  western  border.  The  eastern  half  of  the  plateau  south  of 
the  Colorado  River  extends  south  into  Mexico,  and  there  has  similar  arid 
features,  with  saline  lakes  and  inside  drainage. 

The  plateau  of  Tibet  is  an  intermont  plateau  between  the  main  range  of 
the  Himalayas  and  the  Kuen-Lun  Mountains.  It  is  about  13,000  feet  in 
altitude,  but  is  overlooked  by  mountains  having  an  altitude  of  25,000  to 
29,000  feet,  and  has  its  own  ridge  of  20,000  feet.  It  is  1200  miles  from  east 
to  west,  and  half  this  in  mean  breadth ;  but  its  eastern  half  is  much  encum- 
bered by  ridges. 

The  plateau  of  Quito,  about  300  miles  long,  40  miles  wide,  and  10,000  feet 
above  tide  level,  is  situated  between  two  parallel  Cordilleras  of  the  Andes, 
the  eastern  of  which  contains  among  its  snow-capped  cones  or  domes, 
Cayambe  (19,535,  and  on  the  equator),  Antisana,  Cotopaxi  (19,613),  Sangay ; 
and  the  western,  including  Chimborazo  (20,498  feet),  Pichincha  (15,924  feet), 
and  others.  The  plateau  of  Bolivia  has  an  elevation  of  12,900  feet,  with 
Lake  Titicaca  at  12,830  feet,  and  the  city  of  Potosi  at  13,330  feet. 

In  Europe,  Spain  is  for  the  most  part  a  plateau  about  2250  feet  in  average  elevation; 
Auvergne,  in  France,  another,  of  about  1100  feet ;  Bavaria,  another,  of  1660  feet.  Persia 
is  a  plateau  varying  in  elevation  between  2000  and  4000  feet,  with  high  ridges  in  many 
parts.  The  Abyssinian  plateau,  in  Africa,  has  an  average  elevation  of  more  than  7000 
feet ;  the  region  of  Sahara  about  1500  feet,  except  the  southern  part,  which  lies  mostly  at 
a  greater  altitude  than  650  feet ;  that  of  southern  Africa  south  of  the  parallel  of  10°  S. 
from  3000  to  4000  feet  in  mean  altitude,  and  rising  into  many  high  summits,  with  the  ele- 
vation least  to  the  west. 

MOUNTAINS.  —  (a)  Slopes  of  mountains.  —  The  mountain  mass.  —  The 
slopes  of  the  larger  mountains  and  mountain  chains  are  generally  very 
gradual.  Some  of  the  largest  volcanoes  of  the  globe,  as  Etna  (Sicily)  and 
Loa  (Hawaii) 3  have  a  slope  of  only  six  to  eight  degrees:  such  mountains  are 
broad  cones,  having  a  base  of  40  miles  or  more.  The  higher  volcanic  cones 
of  western  America  are  mostly  25°  to  35°  in  angle  of  slope. 

The  average  eastern  slope  of  the  Eocky  Mountains  seldom  exceeds  10 
feet  a  mile,  which  is  about  one  foot  in  500,  equal  to  an  angle  of  only  7'. 
On  the  west  the  average  slope  is  but  little  less  gradual.  The  rise  on  the 
east  continues  for  600  miles,  and  the  fall  on  the  other  side  for  400  to  500 
miles ;  the  passes  at  the  summit  have  a  height  of  4944  to  10,000  feet ;  and 
above  them,  as  well  as  over  different  parts  of  the  slopes  (especially  on  the 
west),  there  are  ridges  carrying  the  altitude  above  14,000  feet.  The  highest 
part  of  the  range  is  in  Colorado,  where  the  passes  are  11,000  to  13,000  feet 
high ;  while  in  latitude  32°  the  passes  are  about  5200  feet ;  on  the  Central 
Pacific  Eailroad,  6184  feet  high ;  in  Canada,  5264  to  7100  feet  high ;  and  on 
the  Canadian  Pacific  (the  Kicking  Horse  Pass)  5300  feet  high.  The  moun- 
tain mass,  therefore,  is  not  a  narrow  barrier  between  the  east  and  west,  as 
might  be  inferred  from  the  ordinary  maps,  but  a  vast  yet  gentle  swell  of  the 
surface,  having  a  base  1000  miles  in  breadth,  and  the  slopes  diversified  with 
various  mountain  ridges,  or  spreading  out  in  plateaus  at  different  levels. 


THE   EARTH  S   CONTOUR   AND   SURFACE   SUBDIVISIONS. 


27 


In  the  Sierra  Nevada,  the  western  (or  gentler)  slope  is  between  100  and 
250  feet  to  the  mile,  and  the  eastern,  for  a  larger  part  of  its  length,  1000 
feet.  In  the  Andes  the  eastern  slope  is  about  60  feet  in  a  mile,  and  the 
western  100  to  150  feet;  the  passes  are  at  heights  from  12,500  to  16,160 
feet,  and  the  highest  peak  —  Sorata  in  Bolivia  —  25,290  feet.  The  slope  is 
much  more  rapid  than  in  the  Kocky  Mountains.  But  there  is  the  same  kind 
of  mountain  mass  variously  diversified  with  ridges  and  plateaus.  The  exist- 
ence of  the  great  mountain  mass  and  its  plateaus  is  directly  connected  with 
the  existence  of  the  main  ridges.  But  it  will  be  shown  in  another  place  that 
the  ridges  may  have  existed  long  before  the  mass  had  its  present  elevation 
above  the  sea. 

In  the  Appalachians  the  mountain  mass  is  very  much  smaller,  and  the 
component  ridges  are  relatively  more  distinct  and  numerous ;  and  still  the 
general  features  are  on  the  same  principle.  The  greatest  height  —  Mount 
Mitchell  or  Black  Dome  in  North  Carolina  —  is  6707  feet. 

It  is  common  to  err  in  estimating  the  angle  of  a  slope.  To  the  eyes  of  most  travelers, 
a  slope  of  60°  appears  to  be  as  steep  as  80°,  and  one  of  30°  to  be  at  least  50°.  In  a  front 

view  of  a  declivity  it  is  not  possible  to  judge 
rightly.  A  profile  view  should  always  be 
obtained  and  carefully  observed  before  regis- 
tering an  opinion. 

In  Fig.  3  the  bluff  front  facing  the  left 
would  be  ordinarily  called  a  vertical  precipice, 
while  its  angle  ^>f  slope  is  actually  about 

65° ;  and  the  talus  of  broken  stones  at  its  base  would  seein  at  first  sight  to  be  60°, 
when  really  40°. 

4. 


6. 


Fig.  4  represents  a  section  of  a  volcanic  mountain  3°  in  angle ;  Fig.  5,  another,  of  7°,  — 
the  average  slope  and  form  of  Mount  Kea,  Hawaii ;  Fig.  6,  the  same  slope  with  the  top 


7. 


8. 


rounded,  as  in  Mount  Loa ;  Fig.  7,  a  slope  of  15°  ;  Fig.  8,  Jorullo,  in  Mexico,  which  has 
one  side  27°  and  the  other  34°,  as  measured  by  N.  S.  Manross ;  Fig.  9,  a  slope  of  40°,  — 


28  PHYSIOGRAPHIC    GEOLOGY. 

the  steepest  of  volcanic  cones.  The  lofty  volcanoes  of  the  Andes  are  not  steeper  than  in 
Fig.  8,  although  often  represented  with  angles  of  40°  to  50°. 

With  a  clinometer  (see  Fig.  89,  page  100)  held  between  the  eye  and  the  mountain,  the 
angle  of  slope  may  be  approximately  measured.  When  no  instrument  is  at  hand,  it  is  easy 
to  estimate  with  the  eye  the  number  of  times  a  vertical,  as  AB  in  Fig.  5,  is  contained  in  the 
semi-base,  BC  ;  and,  this  being  ascertained,  the  angle  of  slope  may  be  easily  calculated. 
The  ratio  1 : 1  corresponds  to  the  angle  45°  ;  1 :  2  to  26°  34' ;  1 :  3  to  18°  26'  ;  1 :  4  to  14° 
2' ;  1 :  5  to  11°  18|' ;  1 : 6  to  9°  28' ;  1 :  7  to  8°  8' ;  1 :  8  to  7°  7''  ;  1  :  9  to  6°  20£' ;  1 :  10  to 
5°  421'  j  1 : 12  to  4°  46' ;  1 : 15  to  3°  49' ;  1 :  20  to  2°  52'.  The  inclinations  corresponding 
to  these  ratios  may  be  easily  put  into  a  diagram. 

For  altitudes  over  the  United  States,  see  Bulletin  No.  76,  U.  S.  Geol.  Survey,  by 
H.  Gannett,  1891. 

(b)  Ridges.  —  The  ridges  of  a  chain  vary  along  its  course.  After  con- 
tinuing for  a  distance,  they  may  gradually  become  lower  and  disappear  ;  and 
while  one  is  disappearing,  another  may  rise  to  the  right  or  left ;  or  the 
mountain,  for  scores  of  leagues,  may  be  only  a  plateau  without  a  high  ridge, 
and  then  new  ranges  of  elevations  may  appear.  The  Rocky  Mountains  well 
exemplify  this  common  characteristic,  as  may  be  seen  on  any  of  the  recent 
maps.  The  Sierra  Nevada  dies  out  where  the  Cascade  Range  begins ;  and 
each  has  minor  examples  of  the  same  principle.  The  Andes  are  like  the 
Rocky  Mountains ;  only  the  parts  are  pressed  into  narrower  compass,  and 
the  crest  ranges  are  hence  continuous  for  longer  distances.  The  Appalachian 
ridges  rise  and  sink  along  the  course  of  the  chain. 

10-15. 


14 


15 


The  general  idea  of  this  composite  structure  is  shown  in  Figs.  10  to  15, 
where  each  series  of  lines  represents  a  series  of  ridges  in  a  composite  range. 
In  Fig.  10  the  series  is  simple  and  straight ;  in  Fig.  11  it  is  still  straight,  but 
complex ;  in  Fig.  12  the  parallel  parts  are  so  arranged  as  still  to  make  a 
nearly  straight  composite  range;  while  in  Figs.  13  and  14  the  succession 
forms  a  curve  ;  and  in  Fig.  15  there  are  transverse  ridges  in  a  complex  series. 
In  ridges  or  ranges  thus  compounded,  the  component  parts  may  lie  distinct, 
or  they  may  coalesce  so  as  not  to  be  apparent. 

RIVEK  SYSTEMS. — Plateaus  and  mountains  are  the  sources  of  rivers. 
They  pour  the  waters  along  many  channels  into  the  basin  or  low  country 
toward  which  they  slope  ;  and  the  channels,  as  they  continue  on,  unite  into 
larger  channels  and  trunks  which  bear  the  waters  to  the  sea.  The  basin 
and  its  surrounding  slopes  make  up  a  river  system  or  drainage  area.  The 


THE  EARTH'S  CONTOUR  AND  SURFACE  SUBDIVISIONS.  29 

extent  of   such   a  region  will  vary  with   the   position  of  the   mountains 
and  ocean. 

Over  a  continent  there  are  the  interior  and  the  border  river  systems 
or  drainage  areas ;  the  former  very  large  and  few,  the  latter  many  and 
relatively  small. 

In  North  America,  having  the  Rocky  Mountains  on  the  west  and  the 
Appalachian  on  the  east,  the  great  interior  slopes  are  three  :  southward, 
along  the  Mississippi;  eastward,  along  the  St.  Lawrence;  and  northward, 
along  the  Mackenzie  and  other  streams. 

The  tributary  streams  of  the  Mississippi  rise  on  the  west,  among  the 
heights  of  the  Kocky  Mountains,  the  region  in  and  near  the  Yellowstone 
Park  supplying  waters  to  the  Missouri  through  a  number  of  tributaries 
including  the  Yellowstone  and  the  Front  Range  of  Wyoming,  Colorado,  and 
New  Mexico,  giving  origin  to  the  Platte,  Arkansas,  and  Canadian  rivers; 
on  the  north,  in  the  central  plateau  of  the  continent,  in  northern  Minnesota, 
west  of  Lake  Superior,  near  lat.  47°-48°,  long.  93°-96°,  1680  feet  in  elevation 
—  a  region  of  lakes  which  is  the  source  of  the  Mississippi  of  the  maps ; 
and  on  the  east,  in  the  Appalachians,  from  western  New  York  to  Alabama. 
There  are  also  other  rivers  flowing  from  the  west  into  the  Gulf  of  Mexico ; 
but,  in  a  comprehensive  view  of  the  continent,  these  belong  to  the  same 
great  river  system. 

The  St.  Lawrence  commences  in  the  head  waters  of  Lake  Superior,  about 
the  same  central  plateau,  embraces  the  Great  Lakes  with  their  tributaries, 
and  flows  finally  northeastward,  following  a  northeast  slope  of  the  continent. 
North  of  Lake  Superior  and  the  head  waters  of  the  Mississippi,  as  far  as  the 
parallel  of  55°,  there  are  other  streams,  which  also  flow  northeastward, 
deriving  some  waters  from  the  Rocky  Mountains  through  the  Saskatchewan, 
and  reaching  the  ocean  through  Hudson  Bay.  Winnipeg  Lake  is  here  in- 
cluded. These  belong  with  the  St.  Lawrence,  the  whole  together  constituting 
a  second  continental  river  system. 

The  Mackenzie  is  the  central  trunk  of  the  northern  river  system.  Start- 
ing from  near  the  parallel  of  55°,  it  takes  in  the  slopes  of  the  Rocky 
Mountains  adjoining,  and  much  of  the  northern  portion  of  the  continent. 
Athabasca,  Great  Slave,  and  Great  Bear  lakes  lie  in  this  district. 

The  border  river  systems  depend  for  their  extent  011  the  height  and 
slope  of  the  mountains,  the  distance  from  the  coast,  and  the  structure  of  the 
mountain  region.  The  Appalachian  range,  mostly  below  5000  feet  in  height, 
is  150  to  300  miles  from  the  coast.  But  the  mountains  are  a  succession  of 
overlapping  parallel  ridges,  and  the  rivers  in  their  higher  parts  go  back  and 
forth  between  the  ridges,  thus  deriving  a  more  gradual  slope,  a  much  greater 
length,  and  producing  a  longer  range  of  watered  country.  The  Rocky  Moun- 
tains, 10,000  to  over  14,000  feet  high,  are  600  to  1000  miles  from  the  coast. 
But  a  second  chain  of  equal  height  —  that  of  the  Sierra  and  Cascade  ranges, 
with  the  range  of  the  California  peninsula,  which  is  probably  a  southern 
continuation  of  the  line  —  stands  as  a  barrier  to  the  more  eastern  drainage 


30  PHYSIOGRAPHIC   GEOLOGY. 

within  150  miles  of  the  coast,  and  thus  influences  the  extent  of  the  Pacific 
border  river  systems.  The  western  drainage  of  the  Kocky  Mountains,  rising 
partly  in  the  Yellowstone  Park,  and  partly  just  south  of  it,  has  its  outlet 
to  the  ocean  through  the  Colorado  and  Gulf  of  California,  and  along  the 
Columbia  River  and  streams  farther  north,  the  Colorado  and  Columbia 
reaching  salt  water  at  points  1200  miles  apart.  Thus  it  is  that  the  "  Great 
Basin  "  is  without  drainage.  Again,  a  subordinate  range  of  this  chain,  that 
of  the  Coast  Kange,  2000  to  4000  feet  high,  is  a  barrier,  for  800  miles,  to 
most  of  the  drainage  waters  of  the  Sierra  Nevada  and  Cascade  Mountains ; 
and  consequently  the  Sacramento  and  Joaquin  rivers,  and  not  the  ocean, 
receive  all  the  Sierra  waters  for  500  miles,  and  the  Willamette,  the  waters 
of  the  Cascade  Range  for  150  miles. 

South  America  has  an  arrangement  of  interior  river  systems  parallel  to 
that  of  North  America ;  the  Amazon  flowing  eastward,  like  the  St.  Lawrence ; 
the  La  Plata  flowing  southward,  like  the  Mississippi ;  the  Orinoco  and  other 
streams  northward,  like  the  Mackenzie.  This  adds  a  fourth  to  the  charac- 
teristics exhibiting  parallelism  in  structure  between  two  continents,  North 
and  South  America  (page  22).  Africa,  on  the  opposite  side  of  the  Atlantic, 
has  the  arrangement  reversed  as  regards  the  east  and  west  streams  :  the 
great  Niger  empties  into  the  western  ocean,  the  Atlantic  ;  the  Nile  is  the 
northward-flowing  stream ;  but  the  southward-flowing  interior  waters  are 
divided  between  the  Congo  draining  to  the  southwestward  and  the  Zambesi 
to  the  southeastward. 

The  lengths  and  drainage  areas  of  some  of  the  largest  of  rivers  are  as  follows  :  Amazon, 
length  (L.)  =  3545  miles,  drainage-area  (D.)  =  2,264,000  square  miles  ;  La  Plata,  L.  =  2400, 
D.  =  1,250,000  ;  Mississippi,  L.  =  2800  (but  from  its  mouth  to  the  head  of  the  Missouri 
4200),  D.  =  1,285,000 ;  Nile,  L.  =  3815,  D.  =  1,049,000  ;  Congo,  L.  =  2900,  D.  =  1,540,000 ; 
Yenisei,  L.  =  2800,  D.  =  784,500  ;  Amur,  L.  =  2380,  D.  =  583,000  ;  Obi-Irtish,  L.  = 
2320,  D.  =  725,000 ;  Lena,  L.  =  2400,  D.  =  594,000  ;  Yang-tse-Kiang,  L.  =  2800,  D.  = 
548,000  ;  Hoang  Ho  (Yellow  River),  L.  =  2280,  D.  =  537,000. 

The  lengths  of  the  valleys,  excluding  the  minor  beds,  are :  the  Amazon,  2600  miles ; 
the  Mississippi,  1164  ;  the  Nile,  3100. 

II.    SYSTEM    IN    THE    RELIEFS    OR    SURFACE    FORMS    OF    THE 

CONTINENTS. 

Law  of  the  system.  —  The  mountains,  plateaus,  lowlands,  and  river  regions 
are  the  elements,  in  the  arrangement  of  which  the  system  in  the  surface  form 
of  the  continents  is  exhibited.  The  law  at  the  basis  of  the  system  depends 
on  a  relation  between  the  continents  and  their  bordering  oceans,  and  is  as 
follows  :  — 

First.  The  continents  have  in  general  elevated  mountain  borders  and 
a  low  or  basin-like  interior. 

Second.    The  highest  border  faces  the  larger  ocean. 

A  survey  of  the  continents  in  succession  with  reference  to  this  law  will 
exhibit  both  the  unity  of  system  among  them  and  the  peculiarities  of  each, 
dependent  on  their  different  relations  to  the  ocean. 


SYSTEM   IN   THE   SURFACE   FORMS    OF   THE   CONTINENTS. 


31 


(1)  America.  —  The  two  Americas  are  alike  in  lying  between  the  Atlan- 
tic and  the  Pacific.  North  America,  in  accordance  with  the  law,  has  on  the 
Pacific  side  —  the  side  of  the  great  ocean  —  the  Rocky  Mountains,  on  the 
Atlantic  side  the  low  Appalachians,  and  between  the  two  there  is  the  great 
plain  of  the  interior.  This  is  seen  in  the  annexed  section  (Fig.  16)  from 

16. 


west  to  east :  on  the  west,  the  Kocky  Mountains,  with  the  double  crest,  at  b ; 
the  Sierra  Range  at  a ;  between  a  and  b  the  Great  Basin ;  at  d  the  Appa- 
lachians ;  c  the  Mississippi ;  and  between  d  and  b  a  section  of  the  Mississippi 
river  system. 

The  Appalachians,  on  the  east,  reach  an  extreme  height  of  but  6700  feet, 
and  are  in  general  under  2500  feet. 

To  the  north  of  North  America  lies  the  small  Arctic  Ocean,  much  encum- 
bered with  land;  and  without  any  distinct  mountain-chain  facing  the  ocean. 

South  America,  like  North  America,  has  its  great  western  range  of  moun- 
tains, and  its  smaller  eastern  range  (Fig.  17);  and  the  Brazilian  line  (6)  is 

17. 


closely  parallel  to  that  of  the  Appalachians.  The  Andes  (a)  face  the  very 
broad  South  Pacific,  and  have  more  than  twice  the  average  height  of  the 
Rocky  Mountains ;  moreover,  they  rise  more  abruptly  from  the  ocean,  with 
narrow  shore  plains. 

Unlike  North  America,  South  America  has  a  broad  ocean  on  the  north, 
—  the  North  Atlantic  in  its  longest  diameter ;  and  along  this  northern  coast 
a  mountain  chain  extends  through  Venezuela  and  Guiana. 

(2)  Europe  and  Asia.  —  The  land  covered  by  Europe  and  Asia  is  a  single 
area  of  land,  only  partially  double  in  its  nature  (page  22).  Unlike  either  of 
the  Americas,  it  lies  east-and-west,  with  an  extensive  ocean  facing  Asia  on 
the  south ;  and  its  great  feature  lines  are  in  a  large  degree  east-and-west. 
The  small  Arctic  Ocean  is  on  the  north ;  the  larger  North  Atlantic  on  the 
west ;  the  still  larger  North  Pacific  on  the  east :  Africa  and  the  broad  Indian 
Ocean,  singularly  free  from  islands,  are  on  the  south.  The  boundary  is 
a  complex  one,  and  the  land  between  the  Atlantic  and  Pacific  is  over  6000 
miles  broad. 


32  PHYSIOGRAPHIC   GEOLOGY. 

On  the  side  of  the  North  Atlantic  there  are  the  mountains  of  Scan- 
dinavia and  the  British  Isles,  the  former  having  a  mean  height  of  4000  feet 
and  a  maximum,  in  Galdhopig,  of  8400  feet ;  and  farther  south,  the  Alps 
and  other  mountains  of  eastern  Europe,  the  higher  portions  covering  but 
small  areas.  On  the  side  of  the  larger  Pacific  there  are  loftier  mountains 
in  long  ranges  —  the  Shan-a-lin  range  of  Manchuria,  having  peaks  of  10,000 
to  12,000  feet,  and  the  high  Khingan  range  of  15,000  feet,  facing  China.  Off 
the  coast  there  is  still  another  series  of  ranges,  now  partly  submerged,  — 
viz.  those  of  Japan  and  other  linear  groups  of  islands ;  these  stand  in  front 
of  the  interior  chain,  very  much  as  the  Cascade  range  and  Sierra  Nevada  of 
the  Pacific  border  of  America  are  in  advance  of  the  summit  ridges  of  the 
Eocky  Mountains,  and  both  are  alike  in  being  partly  volcanic,  with  cones 
of  great  altitude. 

Thus  viewing  Eurasia  across  its  whole  breadth  from  west  to  east,  there  is 
an  interior  basin  of  immense  extent,  which  includes  some  of  the  lowest  land 
of  the  globe.  The  plains  of  eastern  Europe,  north  of  the  Carpathians,  com- 
prise three  fifths  of  all  Europe,  and  are  situated,  with  reference  to  the 
mountain-border  of  Europe,  like  the  Mississippi  basin  with  reference  to  the 
Appalachians.  Farther  east  there  is  the  low  land  of  the  Caspian- Aral  basin 
of  western  Asia,  a  million  of  square  miles  in  area,  over  a  fourth  of  it  lying 
below  the  sea  level. 

Facing  the  large  and  open  Indian  Ocean,  and  looking  southward,  stand 
the  Himalayas,  —  the  loftiest  of  mountains,  in  which  peaks  of  20,000  feet 
and  over  are  very  numerous,  and  few  passes  are  under  16,000  feet, — called 
the  Himalayas  as  far  as  Kashmir,  and  from  there,  where  a  new  sweep  in  the 
curve  begins,  the  Hindu-Kush,  —  the  whole  over  2000  miles  in  length : 
not  so  long,  it  is  true,  as  the  Andes,  but  continued  as  far  as  the  ocean  in 
front  continues.  The  Kuen-Lun  Mountains,  to  the  north  of  the  Himalayas, 
make  another  crest  to  the  great  chain.  Farther  north  lies  the  great  interior 
arid  plateau,  the  Desert  of  Gobi ;  and  then  rise  other  mountain  chains,  the 
Thian-Shan  to  the  northwest  having  peaks  of  14,000  to  15,000  feet,  the 
Yablonoi  to  the  northeast,  and  farther  north,  the  Altai  facing  Siberia. 
Beyond  these  stretches  Siberia,  an  alluvial  area,  1000  miles  wide. 

18. 


The  diagram  (Fig.  18)  represents  the  general  features  of  a  section  from 
north  to  south  through  the  Himalayas.  At  a,  there  is  the  elevated  land 
of  India ;  between  a  and  6,  the  low  river-plain  at  the  base  of  the  Himalayas ; 
at  b,  the  Himalayas ;  b  to  c,  Plains  of  Tibet ;  c,  the  Kuen-Lun  ridge ;  c  to  d, 
Plains  of  Mongolia  and  Desert  of  Gobi ;  at  d,  the  Altai ;  d  to  N,  the  Siberian 
plains. 


SYSTEM    IX   THE   SURFACE   FOKMS    OF   THE   CONTINENTS.  33 

The  great  desert-plateau  of  Gobi  or  Mongolia,  3000  to  4000  feet  in  eleva- 
tion, is  a  great  interior  basin,  and  the  Altai  and  associated  ranges  are  the 
mountains  facing  the  Arctic  seas.  But  the  distance  to  those  seas  is  so  great 
that  it  is  as  reasonable  to  regard  the  Mongolian  area  as  a  plateau  between 
high  mountain  ranges  facing  the  Indian  Ocean,  and  Arctic  Asia,  like  Arctic 
America,  as  without  any  mountains  bordering  the  small  Arctic  sea. 

The  interior  drainage  system  for  Asia  is  without  outlet.  The  waters  are 
shut  up  within  the  great  basin,  the  Caspian  and  Aral  being  the  seas  which 
receive  the  part  of  those  waters  not  lost  in  the  plains.  The  Volga  and  other 
streams,  from  a  region  of  a  million  of  square  miles,  flow  into  the  Caspian. 
Lake  Baikal,  regarded  as  a  Siberian  lake,  is  30  degrees  of  latitude,  or  over 
2000  miles,  from  the  Arctic  coast. 

The  Urals,  2000  to  3000  feet  in  mean  altitude,  stand  as  a  partial  barrier 
between  Asia  and  Europe,  parallel  nearly  with  the  mountains  of  Norway. 

Looking  over  the  broad  surface  of  North  America  and  of  Eurasia  on  the 
map,  on  page  47,  the  fact  that  the  higher  lands  are  on  the  side  of  the  greater 
ocean  is  strikingly  illustrated.  In  each,  the  dark  shaded  or  more  elevated 
portion  is  mainly  on  the  Pacific  side. 

(3)  Africa.  —  Africa  has  the  Atlantic  on  the  west,  the  broader  Indian 
Ocean  on  the  east,  with  Europe  and  the  Mediterranean  on  the  north,  and  the 
South  Atlantic  and  Southern  Ocean  on  the  south.  The  northern  half  has 
the  east-and-west  position  of  Asia,  and  the  southern  the  north-and-south  of 
America ;  and  its  reliefs  correspond  with  this  structure.  The  Guinea  coast, 
belonging  to  the  northern  half,  projects  west  in  front  of  the  south  Atlantic, 
and  is  faced  by  the  east-and-west  Kong  range,  about  2000  feet  high :  and 
opposite,  on  the  Mediterranean,  there  are  the  Atlas  Mountains,  the  high 
plateau  of  which  is  about  3000  feet;  one  peak  in  the  Atlas  of  Morocco 
is  13,000  feet  high,  although  the  ridges  are  generally  5000  to  7000  feet. 

The  larger  part  of  the  Abyssinian  Plateau  is  6000  to  7000  feet  in  eleva- 
tion, but  it  has  one  summit  of  15,000  feet.  It  extends  into  the  great  plateau 
of  southern  Africa;  and  just  south  of  the  equator  stand  Mount  Kilima-Njaro, 
18,715  feet  high,  and  Mount  Kenia,  18,000  feet,  and  near  the  meridian  of 
30°,  and  2°  S.,  Euwenzori,  19,000  feet  (Stanley).  The  pass  from  Zanzibar 
to  Tanganyika  is  5700  feet.  A  height  of  6000  to  8000  feet  continues  south, 
becoming  nearly  9000  feet  in  the  South  African  Republic.  The  drainage  of 
the  interior  is  consequently  westward,  and  the  Zambesi  is  the  only  stream 
that  breaks  through  and  reaches  the  Indian  Ocean.  Africa  has  been  well 
described  as  a  shut-up  continent,  its  coasts  being  mostly  without  bays. 

19. 


The  section  Fig.   19   gives   a   general   idea  of   its  features  from  south 
to  north    (the  heights  necessarily  much  exaggerated  in  proportion  to  the 
DANA'S  MANUAL — 3 


34  PHYSIOGRAPHIC    GEOLOGY. 

length)  ;  a,  the  southern  mountains ;  b,  the  southern  plateau ;  c.  Lake  Tchad 
depression;  d,  Sahara  plateau;  e,  oases  depression;  /,  mountains  on  the 
Mediterranean,  of  which  there  are  two  or  three  parallel  ranges. 

Africa  has,  therefore,  a  basin-like  form,  but  is  a  double  basin ;  and  its 
highest  mountains  are  on  the  side  of  the  largest  ocean,  the  Indian.  The 
height  of  the  mountains  adjoining  the  Mediterranean  is  the  only  exception 
to  the  relation  to  the  oceans. 

(4)  Australia.  —  Australia  conforms  also  to  the  continental  model.  The 
highest  mountains  are  on  the  side  of  the  Pacific,  — the  larger  of  its  border- 
oceans.  Mountain  ranges  extend  along  the  whole  eastern  border  from 
Portland  in  Victoria  to  Cape  York  in  the  extreme  north.  The  Australian 
Alps,  in  ISTew  South  Wales,  facing  the  southeast  shores,  have  peaks  5000  to 
6500  feet  in  height.  The  Blue  Mountains  next  to  the  north  are  3000  to  4000 
feet  high,  with  some  more  elevated  summits.  On  the  side  of  the  Indian 
Ocean  the  heights  are  1500  to  2000  feet.  The  interior  is  an  arid  region, 
the  center  more  than  600  feet  above  the  sea. 

The  continents  thus  exemplify  the  law  laid  down,  and  not  merely  as 
to  high  borders  around  a  depressed  interior,  —  a  principle  stated  by  many 
geographers,  —  but  also  as  to  the  highest  border  being  on  the  side  of  the 
greatest  ocean.1 

This  difference  between  the  interior  and  the  border  regions  runs  parallel 
with  another  of  geological  nature :  the  border  region  in  its  older  rocks,  if 
not  the  newer,  is  a  region  usually  of  upturned  beds,  and  the  interior,  for  the 
most  part,  of  nearly  horizontal  beds.  The  interior  basin  has  this  feature 
in  North  America,  in  South  America,  and  over  eastern  Europe  in  the  great 
plains  of  Turkey  and  Kussia. 

It  is  owing  to  this  law  that  America  and  Europe  literally  stand  facing 
one  another,  and  pouring  their  waters  and  the  treasures  of  the  soil  into  a 
common  channel,  the  Atlantic.  America  has  her  loftier  mountains,  not  on 
the  east,  as  a  barrier  to  intercourse  with  Europe,  but  off  in  the  remote  west, 
on  the  broad  Pacific,  where  they  stand  open  to  the  moist  easterly  winds 
as  well  as  those  of  the  west,  to  gather  rains  and  snows,  and  make  rivers  and 
alluvial  plains  for  the  continent ;  and  the  waters  of  all  the  great  streams, 
lakes,  and  seas  make  their  way  eastward  to  the  narrow  ocean  that  divides 
the  civilized  world.  Europe  has  her  slopes,  rivers,  and  great  seas  opening 
into  the  same  ocean  ;  and  even  central  Asia  has  her  most  natural  outlet 
westward  to  the  Atlantic.  Thus,  under  this  simple  law,  the  civilized  world 
is  brought  within  one  great  country,  the  center  of  which  is  the  Atlantic, 
uniting  the  land  by  a  convenient  ferriage,  and  the  sides  the  slopes  of  the 
Rocky  Mountains  and  Andes  on  the  west,  and  the  remote  mountains  of 
Mongolia,  India,  and  Abyssinia  on  the  east.2 

This  subject  affords  an  answer  to  the  inquiry,  What  is  a  continent  as 

1  First  announced  American  Jour.  Sci.,  II.,  vols.  iii.  398,  iv.  92,  1847,  and  xxii.  335,  1856. 

2  See  Guyot's  Earth  and  Man. 


SYSTEM   IN   THE   COURSES   OF  THE   EARTH'S   FEATURE   LINES.         35 

distinct  from  an  island  ?  It  is  a  body  of  land  so  large  as  to  have  the  typical 
basin-like  form,  —  that  is,  independent  mountain  chains  on  either  side  of  a 
low  interior.  The  mountain  borders  of  the  continents  vary  from  500  to  1500 
miles  in  breadth  at  the  base.  Hence  a  continent  cannot  be  less  than  a 
thousand  miles  (twice  five  hundred)  in  width. 


20. 


HI.     SYSTEM  IN  THE   COURSES  OF   THE  EARTH'S  FEATURE  LINES. 

The  system  in  the  courses  of  the  earth's  outlines  is  exhibited  alike  over 
the  oceans  and  continents,  and  all  parts  of  the  earth  are  thus  drawn  together 
into  even  a  closer  relation  than  appears  in  the  principle  already  explained. 

The  principles  to  which  the  facts  point  are  as  follows  :  (1)  that  two 
great  systems  of  courses  or  trends  prevail  over  the  world,  a  northwestern  and 
a  northeastern,  transverse  to  one  another;  (2)  that  the  islands  of  the  oceans, 
the  outlines  and  reliefs  of  the  continents,  and  the  oceanic  basins  themselves, 
alike  exemplify  these  systems ;  (3)  that  the  mean  or  average  directions 
of  the  two  systems  of  trends  are  northwest-by-west  and  northeast-by-north ; 
(4)  that  there  are  wide  variations  from  these  courses,  but  according  to  prin- 
ciple, and  that  these  variations  are  often  along  curving  lines  ;  (5)  that,  what- 
ever the  variations,  when  the  lines  of  the  two  systems  meet,  they  meet 
nearly  at  right  angles  or  transversely  to  one  another. 

(1)  Islands  of  the  Pacific  Ocean.  —  The  lines  or  ranges  of  islands  over 
the  ocean  are  as  regular  and  as  long  as  the  mountain  ranges  of  the  land.  To 
judge  correctly  of  the  seeming 
irregularities,  it  is  necessary  to 
consider  that,  in  chains  like  the 
Rocky  Mountains,  or  Andes,  or 
Appalachians,  the  ridges  vary 
their  course  many  degrees  as 
they  continue  on,  sometimes 
sweeping  around  into  some  new 
direction,  and  then  returning 
again  more  or  less  nearly  to 
their  former  course,  and  that 
the  peaks  of  a  ridge  are  very 
far  from  being  in  an  exact  line 
even  over  a  short  course  ;  again, 
that  several  approximately  paral- 
lel courses  make  up  a  chain. 

A.  NORTHWESTERLY  SYSTEM 
OF  TRENDS. — In  the  southwest- 
ern Pacific  the  New  Hebrides 
(Fig.  20)  show  well  this  linear 

arrangement ;  and  even  each  island  is  elongated  in  the  same  direction  with 
the  group.     This  direction  is  nearly  northwest  (N.  40°  W.),  and  the  length 


36 


PHYSIOGRAPHIC   GEOLOGY. 


of  the  chain  is  500  miles.      New  Caledonia,  more   to   the  southwest,  has 
approximately  the  same  course,  — about  northwest.     Between  New  Hebrides 

and  New  Caledonia  lies  another  parallel 
line,  the  Loyalty  Group.  The  Solomon 
Islands,  farther  northwestward,  are  also 
a  linear  group.  The  chain  is  mostly  a 
double  one,  consisting  of  two  parallel 
ranges;  and  each  island  is  linear,  like 
the  group,  and  with  the  same  trend. 
The  course  is  northwest-by-west,  the 
length  600  miles. 

In  the  North  Pacific,  the  Hawaiian 
range  has  a  west-northwest  course.  The 
Sandwich  or  Hawaiian  Islands  (Fig.  21), 
from  Hawaii  to  Kauai,  make  up  the  southeasterly  part  of  the  range,  about 
400  miles  in  length.  Beyond  this,  the  line  extends  to  175°  E.,  making 
a  total  length  of  about  1500  miles,  —  a  distance  as  great  as  from  New 
York  to  the  Great  Salt  Lake  in  the  Eocky  Mountains,  or  from  London  to 
Alexandria. 

22. 


H, Hawaii;  M,Maui;  3, Kahoolawe  ;  4,  Lanai: 
5,  Molokai;  O,  Oahu;  K,  Kauai. 


<?  « 

\ 

o       .. 

10°  s 

"x?V    Q  ^ 

140 

/ 

23. 


16°5                  150° 

W 

'S 

Between  these  groups  lie  the  islands  of  mid  ocean,  all  nearly  parallel  in 
their  courses.     Figs.  22,  23  are  examples. 

The  following  table  gives  the  courses  of  the  principal  chains  of  the  ocean :  — 

Course. 

Hawaiian  range N.  64°  W. 

Marquesas  Islands N.  60°  W. 

Paumotu  Archipelago N.  60°  W. 

Tahitian  or  Society  Islands N.  62°  W. 

Hervey  Islands N.  65°  W. 

Samoan  or  Navigators  Islands N.  68°  W. 

Gilbert,  Tarawan,  or  Kingsmill  Islands N.  34°  W. 

Ralick  group N.  37°  W. 

Radack  group N.  30°  W. 

New  Hebrides N.  40°  W. 

New  Caledonia N.  44°  W. 

North  extremity  of  New  Zealand N.  50°  W. 

Solomon  Islands N.  57°  W. 

Louisiade  group N.  56°  W. 

New  Ireland  . .  .  .N.  65°  W. 


SYSTEM  IN  THE  COURSES   OF   THE   EARTH'S   FEATURE  LINES.       37 

B.  NORTHEASTERLY  SYSTEM  OF  TRENDS.  —  The  body  of  New  Zealand 
has  a  mean  N.  40°  E.  course.  The  line  is  continued  to  the  south,  through 
the  Auckland  and  Macquarie  Islands,  to  58°  S.  To  the  north,  in  nearly  the 
same  line,  near  30°  S.,  lie  the  Kermadec  Islands,  and  farther  north,  near  20° 
S.,  the  Tonga  or  Friendly  Islands. 

The  Ladrones,  north  of  the  equator,  follow  the  same  general  course.  It 
also  occurs  in  many  groups  of  the  northwesterly  system  characterizing  sub- 
ordinate parts  of  those  groups.  Thus,  the  westernmost  of  the  Hawaiian 
Islands,  Niihau,  lies  in  the  north-northeast  line,  and  the  two  lofty  peaks  of 
Hawaii  have  almost  the  same  bearing. 

PACIFIC  ISLAND  CHAINS.  —  The  groups  of  Pacific  islands,  with  a  few 
exceptions,  are  not  independent  lines,  but  subordinate  parts  of  island  chains. 
There  are  three  great  island  chains  in  the  ocean  which  belong  to  the  north- 
westerly system,  —  The  Hawaiian,  the  Polynesian,  and  the  Australasian,  — 
and,  excluding  the  Ladrones,  which  pertain  to  the  western  Pacific,  one 
belonging  to  the  northeasterly  system ;  viz.,  the  Tongan  or  New  Zealand 
chain. 

Hawaiian  chain.  —  This  chain  has  already  been  described. 

Polynesian  chain.  —  This  chain  sweeps  through  the  center  of  the  ocean, 
and  has  a  length  of  5500  miles,  or  nearly  one  fourth  the  circumference  of 
the  globe.  (See  Fig.  24.)  The  Paumotu  Archipelago  (1),  and  the  Tahitian, 
Eurutu,  and  Hervey  Islands  (2,  3,  4)  are  parallel  lines  in  the  chain, 


24. 


\ 


,o  \ 


••*, 


J2 


\\\X 
V* 


1  to  10,  the  Polynesian  chain:  1,  Paumotu  group;  2,  Tahitian;  3,  Rurutu  group;  4,  Hervey  group; 
5,  Samoan,  or  Navigators;  6,  Vakaafo  group;  7,  Vaitupu  group;  8,  Gilbert  group;  9,  Ralick;  10,  Radack; 
11,  Carolines ;  12,  Marquesas ;  13,  Fanning  group ;  14,  Hawaiian,  a  to  h,  part  of  the  Australasian  chain : 
a,  New  Caledonia;  6,  Loyalty  group;  c,  New  Hebrides;  d,  Santa  Cruz  group;  et  Solomon  Islands;  /,  Louisi- 
ade  group;  g,  New  Ireland;  h,  Admiralty  group.  —  D. 


38  PHYSIOGRAPHIC   GEOLOGY. 

forming  its  eastern  extremity  ;  westward  there  are  the  Samoan  (5)  and 
Gilbert  (8)  groups,  and  others  intermediate;  still  northwestward  there  are 
the  Eadack  and  Kalick  groups  (9,  10),  and  in  20°  N.,  on  the  same  line, 
Wakes  Island. 

(a)  The  chain,  as  is  seen,  consists  of  a  series  of  parallel  ranges,  suc- 
ceeding and  overlapping  along  the  general  course,  in  the  manner  illustrated 
on  page  28,  when  speaking  of  mountains,  (b)  It  varies  its  course  gradually 
from  west-northwest  at  the  eastern  extremity  to  north-northwest  at  the 
western,  (c)  Its  mean  trend  is  northwest-by-west  (N.  56°  W.),  the  mean 
trend  of  all  the  groups  of  the  northwesterly  system  in  the  ocean,  (d)  The 
chain  is  a  curving  chain,  convex  to  the  southward,  and  marks  the  position  of 
a  great  central  elliptical  basin  of  the  Pacific  having  the  same  northwesterly 
trend.  The  Hawaiian  is  ou  the  opposite  side  of  it,  slightly  convex  to  the 
north. 

The  Marquesan  range  (12,  Fig.  24)  lies  in  the  same  line  with  the  Fanning  group  (13) 
to  the  northwest,  just  north  of  the  equator ;  and,  if  a  connection  exists,  another  great 
chain  is  indicated,  —  a  Marquesan  chain. 

Australasian  chain  (Fig.  25). — New  Hebrides  (K)  and  New  Cale- 
donia (M)  belong  to  the  Australasian  island  chain.  The  line  of  New 
Hebrides  is  continued  northwestward  in  the  Solomon  group  (I)  and  New 
Ireland,  though  bending  a  little  more  to  the  westward,  and  terminates  in 
Admiralty  land  (G),  near  145°  E.,  where  it  becomes  very  nearly  east-and- 
west :  the  length  of  the  range  is  about  2000  miles.  Taking  another  range 
in  the  chain,  New  Caledonia  (M),  the  course  is  continued  in  the  Louisiade 
group  (H) ;  then  the  north  side  of  New  Guinea  (E),  which  continues  bend- 
ing gradually  till  it  becomes  east-and-west,  near  135°  E.  In  the  southeast, 
belonging  to  the  same  general  line,  there  is  the  foot  of  the  New  Zealand  boot 
(0).  The  coral  islands  between  New  Caledonia  and  Australia  appear  also 
to  be  other  lines  in  the  chain. 

From  New  Guinea  (E,  F),  the  east-and-west  course  is  taken  up  by  Ceram 
(D),  and  again,  more  to  the  south,  in  the  Java  line  of  islands  (A,  B,  C)  ; 
and  from  Java  (B)  the  chain  again  begins  to  rise  northward,  becoming  north- 
west finally  in  Sumatra  (A)  and  Malacca. 

The  several  ranges  make  up  one  grand  island  chain,  with  a  double  curva- 
ture, the  whole  nearly  6000  miles  long.  In  Fig.  25,  a  line  stands  for  each 
group,  and  indicates  its  course  ;  it  shows  the  composite  nature  of  the  chain, 
and  the  curving  course,  in  connection  with  a  prevailing  conformity  to  a 
northwesterly  trend. 

Blending  of  the  Australasian  and  Polynesian  island  chains.  —  The  two 
chains  blend  with  one  another  in  the  region  of  the  Carolines,  Fig.  24  (11). 
This  large  archipelago  properly  includes  the  Kalick  and  Kadack  groups 
Fig.  24  (9,  10).  At  the  Gilbert  group,  Fig.  24  (8),  the  Polynesian  chain 
divides  into  two  parts,  —  the  Ralick  and  Kadack  ranges.  But  the  main 
body  of  the  Archipelago,  Fig.  24  (11),  trends  off  to  the  westward,  and  is  a 


SYSTEM   IN   THE   COURSES    OF   THE   EARTH'S   FEATURE   LINES.        39 

third  branch,  conforming  in  direction  to  the  Australasian  system,     (a  to  h, 
Fig.  24,  are  the  same  as  M  to  G,  Fig.  25.) 

In  other  words,  the  Caroline  Archipelago  forks  at  its  southeastern 
extremity,  —  one  portion,  the  Gilbert,  Radack,  and  Ralick  Islands  (8,  9,  10 
in  Fig.  24),  conforming  to  the  Polynesian  system,  while  the  great  body  of 
the  Caroline  Islands  trends  off  more  to  the  westward  (No.  11),  parallel  with 
New  Ireland  and  the  Admiralty  group  (g,  h  of  the  same  cut),  and  others  of 
the  Australasian  system. 

25. 


A,  B,  C,  Sumatra  and  Java  line  of  islands;  D,  Ceram;  E, 
north  coastof  New  Guinea;  F,  South  New  Guinea;  G, 
Admiralty  Islands;  H,  Louisiade  group;  I,  Solomon;  J, 
Santa  Cruz  group;  K,  New  Hebrides;  L,  Loyalty  group; 
M,  New  Caledonia;  N,  high  lands  of  northeast  Australia; 
O, .New  Zealand;  ab,  northwest  shore  of  Borneo;  cd, 
East  Borneo;  ef,  west  coast  of  Celebes;  gh,  west  coast 
of  Gilolo.  — D. 

New  Zealand  chain.  —  The  ranges  in  this  chain  are  mentioned  on  page  37. 
The  whole  length,  from  Macquarie  Island,  on  the  south,  to  Vavau,  a  volcanic 
island  terminating  the  Tonga  range,  on  the  north,  is  2500  miles.  To  the 
east  of  New  Zealand  lie  Chatham  Island,  Beverly,  Campbell,  and  Emerald, 
which  correspond  to  another  range  in  the  chain. 

This  transverse  chain  is  at  right  angles  with  the  Polynesian  system  at 
the  point  where  the  two  meet.  Moreover,  it  is  nearly  central  to  the  ocean. 
The  central  position,  great  length,  and  rectangularity  to  the  northwest 
ranges  give  great  significance  to  this  New  Zealand  or  northeasterly  system 
of  the  ocean. 

(2)  Islands  of  the  Pacific  and  Atlantic  Oceans.  — The  trend  of  the  Pacific 
Ocean  as  a  whole  corresponds  with  that  of  its  central  chain  of  islands,  and 
very  nearly  with  the  mean  trend  of  the  whole.  It  is  a  vast  channel,  elon- 
gated to  the  northwest.  The  range  of  heights  along,  northeastern  Australia 
(N,  Fig.  25)  runs  northwesterly  and  passes  by  the  head  of  the  great  gulf 
(Carpentaria)  on  the  north ;  and  the  opposite  side  of  the  ocean  along  North 
America,  or  its  bordering  mountain  chain,  has  a  similar  mean  trend.  A 
straight  line  drawn  from  northern  Japan  through  the  eastern  Paumotus  to 


40  PHYSIOGRAPHIC   GEOLOGY. 

Fuegia  may  be  called  the  axis  of  the  ocean.  This  axial  line  is  nearly  half 
the  circumference  of  the  globe  in  length,  and  the  transverse  diameter  of  the 
ocean  full  one  fourth  the  circumference :  so  that  the  facts  relating  to  the 
Pacific  chains  must  have  universal  importance. 

The  North  Atlantic  Ocean  trends  to  the  northeast.  —  or  at  right  angles, 
nearly,  to  the  Pacific ;  this  being  the  course  of  the  coasts,  and  therefore  of 
the  channel.  Moreover,  it  is  the  course  of  the  central  plateau  along  the 
bottom  of  the  north  Atlantic. 

The  Asiatic  coast  of  the  Pacific  has  the  direction  of  the  northeasterly 
system.  The  course  is  not  nearly  a  straight  line,  like  the  corresponding 
eastern  coast  of  North  America,  but  consists  of  a  series  of  curves,  which 
series  is  repeated  in  the  island  chains  off  the  coast  and  in  the  mountains  of 
the  country  back.  Moreover,  the  curves  meet  one  another  nearly  at  right 
angles.  The  first  one,  that  of  the  Aleutian  Islands,  extends  as  a  great 
festoon  between  the  two  continents,  America  and  Asia.  The  last  one,  which 
is  1800  miles  long,  commences  in  Formosa,  and  extends  along  by  Luzon, 
Palawan,  and  western  Borneo  (ba,  Fig.  25)  to  Sumatra,  and  terminates  at 
right  angles  with  Sumatra;  and  another  furcation  of  it  (dc)  passes  by 
eastern  Borneo  or  Celebes,  and  terminates  at  right  angles  with  Java  and  the 
islands  just  east.  The  rectangularity  of  the  intersections  is  thus  preserved ; 
and  the  curve  of  the  Australasian  chain  has  in  this  way  apparently  deter- 
mined the  triangular  form  of  Borneo. 

The  Aleutian  Islands  (range  No.  1)  has  a  length  of  1000  miles.  The  Kamchatka  range 
(No.  2)  commences  at  right  angles  with  the  termination  of  the  Aleutian,  and  bends  around 
till  it  strikes  Japan  at  a  right  angle.  The  Japan  range  (No.  3)  commences  north  in  Sa- 
ghalien,  and  curves  around  to  Corea.  The  Loochoo  range  (No.  4)  leaves  Japan  at  a  right 
angle,  and  curves  around  to  Formosa.  The  Formosa  range  (No.  5)  is  explained  above. 
There  is  apparently  a  repetition  of  the  Formosa  system  in  the  Ladrones  near  lon- 
gitude 145°  E. 

(3)  East  and  West  Indies.  —  The  general  courses  in  the  East  Indies  have 
been  mentioned  on  pages  38,  39.     In  the  West  Indies  and  Central  America 
there  is  a  repetition  of  the  curves  of  the  East  Indies.     The  course  of  the 
range  along  Central  America  corresponds  to  Sumatra  and  Java ;  and  the  line 
of  Florida  and  the  islands  to   the   southeast  makes  another  range  in  the 
same  system. 

(4)  The  American  continents. — In  North  America,  the  northwest  system 
is  seen  in  the  general  course  of  the  Rocky  Mountains,  the  Cascade  Range, 
and  Sierra  Nevada ;  in  Florida ;  in  the  line  of  lakes,  from  Lake  Superior  to 
the  mouth  of  the  Mackenzie ;  in  the  southwest  coast  of  Hudson  Bay  ;  in 
the  shores  of  Davis  Straits  and  Baffin  Bay ;  —  and  with  no  greater  divergen- 
cies from  a  common  course  than  occur  in  the  Pacific.     The  northeast  system 
is  exemplified  in  the  Atlantic  coast  from  Newfoundland  to  Florida,  and,  still 
farther  to  the  northeast,  along  the  coast  of  Greenland ;  and  to  the  south- 
west, along  Yucatan,  in  Central  America.     The  Appalachian  Mountains,  the 
river  St.  Lawrence  to  Lake  Erie,  and  the  northwest  shore  of  Lake  Superior, 
repeat  this  trend. 


41 

There  are  curves  in  the  mountain  ranges  of  eastern  North  America,  like 
those  of  eastern  Asia.  The  Green  Mountains  run  nearly  north-and-south ; 
but  the  continuation  of  this  line  of  heights  across  New  Jersey  into  Penn- 
sylvania curves  around  gradually  to  the  westward.  The  Alleghanies,  in 
their  course  from  Pennsylvania  to  Tennessee  and  Alabama,  have  the  same 
curve.  There  appears  also  to  be  an  outer  curving  range  bordering  the  ocean, 
extending  from  Newfoundland  along  Nova  Scotia,  then  becoming  submerged, 
though  indicated  in  the  sea-bottom,  and  continued  by  southeastern  New 
England  and  Long  Island. 

Between  this  latter  range  and  that  of  the  Green  Mountains  lie  one  or 
more  great  basins  of  ancient  geological  time,  while  to  the  westward  of  the 
Green  Mountains  and  Alleghanies  was  the  grand  interior  basin  of  the  con- 
tinent. The  two  were  to  a  great  extent  distinct  in  their  geological  history, 
being  apparently  independent  in  their  coal  deposits  and  in  some  other 
formations. 

In  South  America,  the  north  coast  has  the  same  course  as  the  Hawaiian 
chain,  or  pertains  to  the  northwest  system ;  and  the  coast  south  of  the  east 
cape  belongs  to  the  northeast  system ;  and  hence  the  outline  of  the  continent 
makes  a  right  angle  at  the  cape.  The  northeast  course  is  very  nearly  that 
of  eastern  North  America  and  New  Zealand.  The  northwest  is  repeated  in 
the  west  coast  by  southern  Peru  and  Bolivia,  and  the  northeast  in  the  coast 
of  northern  Peru  to  Darien :  so  that  this  northern  part  of  South  America, 
if  the  Bolivian  line  were  continued  across,  would  have  nearly  the  form  of  a 
parallelogram.  South  of  Bolivia  the  Andes  correspond  to  the  northeast 
system,  although  more  nearly  north-and-south  than  usual. 

(5)  Islands  of  the  Atlantic.  —  The  Azores  have  a  west-northwest  trend, 
like  the  Hawaiian  chain,  and  are  partly  in  three  lines,  with  evidences  also  of 
the  transverse  system.     The  Canaries,  as  Von  Buch  has  shown,  present  two 
courses  at  right  angles  with  one  another,  —  a  northwest  and  a  northeast. 

Again,  the  line  of  the  southeast  coast  of  South  America  extends  across 
the  ocean,  passing  along  the  coast  of  Europe  and  the  Baltic ;  and  the  moun- 
tains of  Norway  and  the  feature  lines  of  Great  Britain  are  approximately 
parallel  to  it. 

(6)  Asia  and  Europe.  —  In  Asia,  the  Sumatra  line,  taken  up  by  Malacca, 
turns  northward,  until  it  joins  the  knot  of  mountains  formed  by  the  meeting 
of  the  range  facing  the  Pacific  and  that  facing  the  Indian  Ocean.     At  this 
point,  and  partly  in  continuation  of  a  Chinese  range,  commence  the  majestic 
Himalayas,  —  at  first  east-and-west,  at  right   angles  with  the  termination 
of  the  Malacca  line,  then  gradually  rising  to  west-northwest.     The  course 
is    continued    northwestward    in   the    Hindu-Kush,    extending   toward   the 
Caspian,  —  in  the  Caucasus,  beyond  the  Caspian,  and  in  the   Carpathians, 
beyond  the  Black  Sea,     The  northwest  course  appears  also  in  the  Persian 
Gulf,  and  the  plateaus  adjoining,  in  the  Red  Sea,  the  Adriatic   and  the 
Apennines. 


42  PHYSIOGRAPHIC   GEOLOGY. 

Recapitulation. — From  this  survey  of  the  continents  and  oceans  it 
follows :  — 

That,  while  there  are  many  variations  in  the  courses  of  the  earth's 
feature-lines,  there  are  two  directions  of  prevalent  trends,  —  the  northwest- 
erly and  the  northeasterly ;  that  the  Pacific  and  Atlantic  have  thereby  their 
positions  and  forms,  the  islands  of  the  oceans  their  systematic  groupings, 
the  continents  their  triangular  and  rectangular  outlines,  and  the  very  physi- 
ognomy of  the  globe  an  accordance  with  some  comprehensive  law. 

It  has  been  observed,  first  by  Professor  R.  Owen,  of  Indiana  (1857),  that  the  outlines 
of  the  continents  lie  in  the  direction  of  great  circles  of  the  sphere,  which  great  circles  are, 
in  general,  tangential  to  the  arctic  or  antarctic  circle.  By  placing  the  north  pole  of  a 
globe  at  the  elevation  23°  28'  (equal  to  the  distance  of  the  arctic  circle  from  the  pole  or 
the  tropical  from  the  equator),  and  revolving  the  globe  eastward,  part  of  these  conti- 
nental outlines,  on  coming  down  to  the  horizon  of  the  globe,  will  be  found  to  coincide  with 
it ;  and  on  revolving  it  westward,  most  of  the  other  lines.  Other  great  lines,  as  part  of 
those  of  the  Pacific,  are  pointed  out  as  tangents  to  the  tropical  circles  instead  of  the  arctic. 
But  there  are  other  equally  important  lines  which  accord  with  neither  of  these  two  systems, 
and  a  diversity  of  exceptions  when  we  compare  the  lines  over  the  surfaces  of  the  conti- 
nents and  oceans. 

If  the  views  of  Mr.  Owen  are  right,  the  direction  of  coast  lines  on  the  parallel  of  66°  32' 
north  or  south  should  be  east  arid  west  (being  tangent  to  the  antarctic  circle),  and  on  the 
equator,  about  N.  23°  28'  E. ;  and  the  trend  in  other  places  intermediate  between  these 
extremes.  And  in  the  tropical  part  of  the  ocean,  great  circles  tangent  to  the  tropical  circles 
would  have  the  course  N.  66°  32'  W.  crossing  the  equator,  but  be  E.-W.  on  the  tropical 
circles  ;  and  between  the  two  positions  between  N.  66°  32'  W.  and  E.-W.  The  map 
Csee  page  47)  shows  how  far  these  are  the  actual  courses. 

IV.    OCEANIC    AND    ATMOSPHERIC    MOVEMENTS    AND 
TEMPERATURE. 

The  earth  has  east-west  differences,  as  already  pointed  out,  in  the  depths 
of  its  oceans  (page  19).  But  of  greater  importance  are  the  east-west  or 
front-and-rear  contrasts  which  are  a  consequence  of  its  diurnal  revolution. 
Ordinary  observation  recognizes  only  the  rising  and  setting  of  the  sun,  and 
day  and  night,  as  the  chief  consequences  of  the  eastward  rotation.  But 
these  are  only  the  most  obvious.  The  results  are  manifested  universally  in 
the  climates  of  the  globe,  the  winds,  the  tides,  and  oceanic  currents,  in  the 
earth's  magnetic  currents,  in  the  geological  action  of  waters  of  the  ocean 
and  land,  the  distribution  of  plants  and  animals;  and  they  give  to  the 
eastern  and  western  sides  of  the  continents,  or  the  front  and  rear,  differences 
which  are  profound  in  influence  both  physically  and  physiologically.  The 
effects  are  diversified  and  extreme.  They  are  moderated  by  the  nutation  of 
the  earth's  axis  in  its  annual  revolution,  which  gives  the  earth  its  winters 
and  summers;  but  they  are  none  the  less  real  and  fundamental.  Ferrel 
obtained  a  mathematical  expression  for  the  relation  of  the  rotation  to  the 
winds,  and  announced  the  fundamental  law  (1858)  that  "in  whatever  direc- 
tion a  body  moves  on  the  earth's  surface,  there  is  a  force,  arising  from  the 


OCEANIC    AND    ATMOSPHERIC   MOVEMENTS   AND   TEMPERATURE.     43 

earth's  rotation,  which  tends  to  deflect  it  to  the  right  in  the  northern  hemi- 
sphere, but  to  the  left  in  the  southern." 

To  illustrate  fully  the  effects  occasioned  by  the  rotation  would  require 
volumes.  A  few  only  are  presented  in  the  following  brief  account  of  tides, 
oceanic  currents  and  temperature,  winds  and  climates. 

THE  TIDAL  WAVE. 

The  great  tidal  wave,  due  to  the  attraction  of  the  sun  and  moon,  is  a 
wave-movement  in  the  ocean  to  its  bottom.  It  goes  westward  because  of 
the  earth's  eastward  rotation,  with  consequently  the  same  rate  of  progress, 
or  1000  miles  an  hour  at  the  equator;  and  12,000  miles  (half  the  earth's 
circumference)  is  the  length  of  a  single  wave.  The  Pacific  is  too  narrow  to 
contain  over  half  of  the  wave-curve ;  and  the  Atlantic  can  contain  trans- 
versely but  a  quarter  of  it.  After  leaving  the  Pacific  its  course  is  north- 
westerly in  both  the  Indian  Ocean  and  the  Atlantic.  The  height  of  the 
wave  can  be  measured  only  on  islands  in  the  open  ocean,  since  shelving 
shores  and  bays  increase  its  elevation  and  its  power  as  a  geological  agent. 
At  the  prominent  American  headlands  in  the  north  Atlantic,  the  height 
of  the  tide  is  only  one  to  two  feet ;  being  at  Cape  Hatteras  two  feet  after 
traversing  some  miles  of  coast  region  under  600  feet  in  depth,  and  only 
one  foot  at  southeastern  Nantucket.  But  the  actual  height  of  the  tide, 
according  to  G.  H.  Darwin,  is  only  one  third  of  an  inch. 

The  dynamical  effects  of  the  tidal  wave  come  up  for  consideration  under 
the  head  of  The  Ocean. 

OCEANIC  CURRENTS  AND  TEMPERATURE. 

(1)  Oceanic  currents.  —  The  general  system  of  oceanic  currents  is  simple. 
In  the  tropical  portion  of  the  ocean,  either  side  of  a  narrow  equatorial  belt, 
the  great  movement  or  current  is  westward,  corresponding  with  the  course 
of  the  trade-winds ;  as  if  it  were  a  consequence  chiefly  (as  many  physicists 
believe)  of  the  propelling  winds.  Beaching  the  continent  that  lies  to  the 
westward,  the  moving  waters  are  turned  poleward.  Having  passed  the 
parallel  of  35°  or  40°,  the  flow  diverges  more  and  more  from  the  continent, 
and  crosses  the  ocean  eastward  to  its  eastern  continental  border ;  and  there, 
if  there  were  no  great  passage-way  in  the  ocean  basin  opening  toward  the 
poiar  regions,  all  would  be  forced  to  turn  southward  toward  the  region  of 
the  trades,  there  to  start  anew  in  the  great  elliptical  circuit. 

The  north  Pacific  has  the  polar  regions  nearly  shut  off  from  it,  for 
Bering  Sea  is  shallow,  and  Bering  Strait  has  a  depth  of  only  150  feet,  so 
that  the  circuit  is  here  of  the  normal  kind.  But  the  north  Atlantic  has  a 
broad  open  way  into  the  Arctic  seas,  and  the  shallow  region  over  which  it 
passes  —  the  Scandinavian  plateau  —  has  a  depth  on  it  of  1500  to  3000  feet. 
Consequently,  only  part  of  the  waters  turns  southward  along  the  submerged 
European  border  —  a  large  part  keeping  on  its  course  northeastward,  along 
by  Great  Britain,  and  northward,  by  Iceland,  into  the  polar  seas. 


44  PHYSIOGRAPHIC   GEOLOGY. 

The  rate  of  flow  of  the  tropical  current  is  increased  somewhat  after 
striking  the  borders  of  a  continent,  because  of  the  diminished  depth.  As  it 
passes  on  beyond  the  parallel  of  30°  and  35°,  the  flow  becomes  more  and  more 
easterly  in  course,  in  consequence  of  loss  of  motion  by  friction.  In  the 
tropical  region,  the  movement  westward  indicates  a  less  rapid  rate  of  move- 
ment than  the  earth's  surface,  in  its  daily  eastward  rotation.  But  beyond 
30°  the  rate  of  flow  is  faster  than  the  rotation  there ;  and  hence  the  result  is 
an  eastward  movement.  As  the  waters  continue  on  to  the  Arctic,  friction 
further  diminishes. the  flow,  and  while  part  goes  on  northeastward  north  of 
Asia,  the  rest  lags  and  goes  northward  and  northwestward.  From  the  full 
polar  seas  the  waters  must  of  necessity  escape  southward ;  the  lagging  part 
takes  a  course  along  the  Greenland  border  and  down  Baffin  Bay,  making 
the  Labrador  current ;  and  also  a  submarine  course  along  the  western  half 
of  the  ocean's  bottom,  while  the  rest  returns  along  the  ocean's  bottom, — 
especially  along  its  eastern  half,  —  and  thus  the  Atlantic  circuit  is  completed. 
In  the  accompanying  sketch,  WE  is  the  equator  with  30°  and  60°  par- 
allels of  latitude  north  and  south  of  it.  North,  the  ellipse  represents  the 
general  movement  in  the  north  Atlantic ;  the  branch 

' at  P,  the  flow  poleward,   and  the  current  at  L,  the 

returning  Labrador  current. 

The  trends  of  the  continental  coasts,  and  their  larger 
bays,  gulfs,  or  seas,  and  bordering  island  groups,  have 
much  influence  on  the  course  and  character  of  the 
current.  Owing  to  the  position  of  the  north  coast  of 
South  America  with  reference  to  the  opposite  coast  of 
Africa,  the  circuit-stream  of  the  south  Atlantic  as  it 
flows  westward  contributes  a  considerable  branch  to 
the  north  Atlantic  circuit ;  and  because  of  the  outlet 
among  the  East  India  Islands,  the  circuits  of  the  north 
and  south  Pacific  lose  part  of  their  waters  by  their 
passing  off  into  the  Indian  Ocean ;  and  still  they  are  plainly  distinguishable 
off  Japan,  and  off  Australia,  in  the  currents  and  their  temperature. 

The  most  remarkable  example  of  the  effect  of  gulfs  or  seas  and  islands 
is  that  afforded  by  the  West  India  seas  and  islands.  The  West  India  sea 
faces  part  of  the  slowly  advancing  ocean-stream.  It  has  an  area  of  nearly 
2,000,000  square  miles.  Though  rudely  fenced  in  by  the  Windward  Islands, 
there  are  spaces  over  3000  feet  deep  between  the  most  of  them,  and  less 
than  twice  this  at  the  chief  entrance.  From  the  Caribbean  Sea  the  waters, 
after  a  circuit,  escape  partly  between  the  islands  northwestward ;  but  part 
pass  the  narrow  Yucatan  channel  with  an  hourly  movement  of  one  fourth  of 
a  mile,  and  raise  the  level  of  the  Gulf  of  Mexico  three  feet  above  its  nat- 
ural level,  and,  at  the  same  time,  act  as  a  hydrostatic  reservoir  to  make  of 
the  escaping  waters  the  Gulf  Stream,  which  flows  through  the  Florida  straits 
(according  to  Commander  Bartlett)  at  a  mean  rate  of  three  miles  an  hour, 
and  at  a  maximum,  for  15  miles  in  the  axis  of  the  stream,  as  high  as  5i 


OCEANIC   AND    ATMOSPHERIC    MOVEMENTS    AND   TEMPERATURE.     45 

miles  an  hour.  Off  Charleston  the  mean  hourly  flow  is  three  miles  ;  from 
there  to  New  York  it  diminishes  to  2J  miles,  and  off  the  Banks  of  New- 
foundland it  is  but  1£  to  two  miles.  The  rate  of  flow  and  other  characters 
of  the  stream  are  thus  largely  due  to  the  existence  between  the  American 
continents  of  the  great  Mexican  Gulf.  The  Mediterranean  Sea,  on  the 
opposite  side  of  the  ocean,  has  no  such  effects,  partly  because  it  is  on  the 
wrong  side  of  the  ocean  for  the  production  of  them. 

The  straits  of  Florida  have  a  width  of  about  48  miles  off  Jupiter  Inlet, 
and  a  maximum  depth  of  2634  feet ;  and  95  billion  tons  of  water  pass 
per  hour.  The  current  reaches  a  zero  velocity  at  a  depth  of  1800  to  2100 
feet.  North  of  the  Bahamas  the  stream  passes  over  the  plateau  bottom. 
to  Charleston  with  a  mean  depth  of  2400  feet,  and  width  of  75  to  100 
miles ;  and  thence  to  Cape  Hatteras,  the  depth  diminishing  to  1800  feet. 
North  of  Cape  Hatteras,  the  coastward  wall  is  in  a  depth  of  about  390 
feet;  and  inside  of  this  wall,  as  well  as  to  the  eastward  of  the  stream 
and  beneath  it,  flow  the  cold  waters  of  the  Labrador  current.  Owing  to  -the 
delay  of  the  waters  in  the  Caribbean  Sea  and  the  Mexican  Gulf  the  heat  of 
the  tropical  waters  is  much  augmented  for  distribution  along  their  northeast- 
ward course. 

In  the  central  North  Atlantic,  between  the  eastward  and  westward  parts 
of  the  circuit,  exists  a  region  of  calms  in  both  winds  and  currents,  with 
great  areas  of  floating  seaweeds,  which  is  called  the  Sargasso  Sea.  The  sea- 
weeds shelter  a  large  variety  of  fishes  and  inferior  living  species. 

A  belt  in  the  equatorial  region,  just  north  of  the  equator,  is  the  course  of 
a  counter-current  both  in  the  Pacific  and  Atlantic.  Currents  are  generally 
made  in  the  ocean  by  the  prevailing  winds ;  and  local  and  temporary  cur- 
rents, often  of  great  geological  importance,  by  the  winds  of  a  long-continued 
storm. 

(2)  Oceanic  temperature.  —  The  currents  of  the  ocean  are  a  means  of  dis- 
tributing its  heat  or  cold  over  the  globe,  and  making  cold  or  warm  climates 
for  land  and  sea.  Tropical  currents  carry  tropical  heat  to  the  colder  regions 
of  the  globe;  and,  conversely,  the  cold- temperate  and  polar  currents  convey 
cold ;  but  the  former  mostly  as  a  superficial  flow,  seldom  affecting  depths 
below  3000  feet,  while  the  latter  move  at  all  depths  from  the  top  to  the 
ocean's  bottom.  The  colder  waters  are  the  heavier ;  but  when  flowing  along 
a  coast  region  as  a  lagging  current,  they  move  up  the  shelving  bottom  to  the 
surface  in  spite  of  any  warm  waters  in  their  way ;  and  whatever  shoals  they 
encounter  in  their  course,  they  spread  up  and  over  them,  only  a  little  affected 
in  temperature  by  the  waters  they  displace. 

Superficial  effects  over  the  ocean.  —  As  a  consequence  of  the  elliptical 
movement  pointed  out,  and  illustrated  in  Fig.  26,  the  waters  of  the  tropical 
or  warm  side  in  the  circuit  strike  the  east  borders  of  the  continents ;  and 
those  of  the  high  latitude,  or  cold  side,  the  west  borders.  They  therefore 
tend  to  widen  the  areas  of  warm  water  on  the  west  side  of  an  ocean,  and 


46  PHYSIOGRAPHIC    GEOLOGY. 

narrow  the  areas  on  the  east  side.  The  cold  or  polar  latitudes,  as  has 
been  explained,  send  a  returning  current  along  the  continental  borders 
equatorward,  which  may  be  stronger  on  the  eastern  or  western  border, 
according  to  geographical  conditions,  and  thus  these  cold  waters  may  mod- 
ify the  temperature  and  position  of  the  currents  in  the  warmer  latitudes. 
Thirdly,  owing  to  the  effect  of  the  more  rapid  flow  of  the  current  along  the 
borders  of  the  continents,  the  currents  often  carry  the  isothermals  poleward, 
making  poleward  bends  or  loops  in  their  courses ;  and  these  may  be  greatly 
increased  in  prominence  or  definition  by  the  polar  current  along  the  con- 
tinental borders. 

In  Fig.  27,  the  elliptical  line  (A'B'AB)  represents  the  course  of  the  current  in  an 
ocean  south  of  the  equator  (EQ).  If  now  the  movement  in  the  circuit  were  equable, 

an  isothermal  line,  as  that  of  68°,  would  extend  obliquely 
27 •  ^       across,  as  nn :  it  would  be  thrown  south  on  the  west  side 

of  the  ocean  by  the  warmth  of  the  torrid  zone,  and  north 
on  the  east  side  by  the  cooling  influence  derived  from  its 
flow  in  the  cold-temperate  zone.  But  if  the  current,  in- 
stead of  being  equable  throughout  the  area,  were  mainly 
apparent  near  the  continents  (as  is  actually  the  fact),  the 
isothermal  line  should  take  a  long  bend  near  the  coasts, 
as  in  the  line  A'r'rrrrA,  or  a  shorter  bend  A'ss',  ac- 
Oceanic  Currents,  D.  '58.  cording  to  the  nature  of  the  current.  This  form  of  the 

isothermal  line  of  68°  on  the  chart  indicates  the  exist- 
ence of  the  circuit  movement  in  the  ocean,  and  also  some  of  its  characteristics. 

For  example,  the  westward  tropical  flow  in  the  north  Atlantic  carries  its 
warm  waters  over  the  Bermudas,  bending  northward  the  isotherm  of  68° 
(see  map,  page  47),  and  also  that  of  62°;  and  in  the  south  Atlantic,  bending 
the  isotherms  of  74°  and  68°  far  away  from  the  equator,  the  latter  to  latitude 
30°;  whils  on  the  west  side  of  Europe  and  Africa,  as  no  tropical  flow  reaches 
the  borders,  and  only  the  high-latitude  current,  the  isotherm  of  68°  is  carried 
in  the  north  Atlantic  to  15°  N.,  and  in  the  south  Atlantic  up  to  6°  S.  Con- 
sequently the  interval  between  the  isotherms  of  68°  in  the  eastern  part  of  the 
Atlantic  Ocean  is  only  21°  in  width,  while  it  is  64°  in  the  western. 

The  isotherms  on  the  following  chart  (page  47)  mark  the  points  which 
have  equal  mean  temperature  for  the  coldest  winter  month,  and  the  tem- 
peratures are  those  of  a  surface  layer  of  the  ocean  90  to  180  feet  deep. 
For  the  northern  hemisphere  the  month  of  greatest  mean  cold  is  January  or 
February,  and  for  the  southern,  July  or  August.  The  chart,  while  isothermal, 
differs  widely,  therefore,  from  other  isothermal  charts,  and  has  been  named 
Isocrymal,  from  the  Greek  for  equal  and  cold  (10-09,  K/OV/AO'S).  The  line  of 
68°  F.,  for  example,  passes  through  points  in  which  the  mean  temperature 
of  the  surface  water  in  the  coldest  month  of  the  year  is  68°  F. ;  so  with  the 
lines  of  62°,  56°,  etc.  All  of  the  chart  between  the  lines  of  68°,  north  and 
south  of  the  equator,  is  called  the  Torrid  Zone  of  the  ocean's  waters ;  the 
region  between  68°  and  35°,  the  Temperate  Zone;  and  that  beyond  35°,  the 
Frigid  Zone.  The  line  of  68°  is  that  limiting  the  coral-reef  seas  of  the  globe, 


OCEANIC   AND   ATMOSPHERIC   MOVEMENTS   AND   TEMPERATURE.      47 


^^MDA/m^i 


48  PHYSIOGRAPHIC   GEOLOGY. 

or  those  in  which  reef-making  corals  grow",  so  that  the  coral-reef  seas  and 
Torrid  Zone  thus  have  the  same  limits. 

In  the  Pacific,  the  effects  are  no  less  striking  than  in  the  Atlantic,  on  the 
west  side  of  the  American  continent.  Owing  to  the  cold-latitude  waters  that 
flow  equatorward,  the  isotherm  of  68°  reaches  the  South  American  coast  at 
its  west  cape  in  latitude  4°  S.,  and  thus  a  tropical  temperature  is  excluded 
from  nearly  the  whole  of  it.  In  the  north  Pacific,  the  cooling  effect  is  much 
less,  because  of  the  barrier  to  the  arctic  waters  at  the  shallow  Bering  Strait ; 
the  isotherm  terminates  against  the  coast  at  23°.  But  on  the  east  boarder  of 
Asia  and  Australia,  or  the  west  side  of  the  ocean,  the  width  of  the  area 
between  the  north  and  south  isotherms  of  68°  is  65°,  and  the  mean  width  in 
the  central  Pacific  is  about  55°. 

The  warm  Gulf  Stream  extends  its  effects  over  the  whole  breadth  of  the 
north  Atlantic,  even  to  Great  Britain  and  Iceland  and  the  polar  seas,  as 
is  indicated  on  the  map  by  the  long  loops  in  the  isotherm  of  44°  and  35°. 
The  warm  waters  extend  to  Spitzbergen  near  82°  N.,  and  to  the  west  side  of 
Nova  Zembla,  where  the  absence  of  ice  in  summer  is  its  effect ;  and  in  favor- 
able times  it  goes  still  farther  east.  Thus  the  heat  of  the  tropics  is  made  to 
temper  arctic  climate.  But  by  the  time  the  waters  have  reached  the  polar 
circle  they  have  lost  all  tropical  heat,  and  are  warm  only  from  contrast  with 
the  mean  temperature  of  the  northern  latitude. 

The  effects  of  the  polar  waters  along  the  east  borders  of  North  America 
are  strongly  marked,  because  they  there  pass  alongside  of  the  warm  Gulf 
Stream  from  the  south.  The  southward  course  near  the  continent  of  the 
isotherm  of  35°  to  the  southern  angle  of  Newfoundland,  and  the  termina- 
tion of  the  isotherms  of  50°,  56°,  and  62°  at  Cape  Hatteras,  are  a  conse- 
quence of  the  Labrador  waters.  Down  to  this  cape  these  cold  waters  cover 
a  cold  belt  inside  of  the  Gulf  Stream ;  but  farther  south  they  are  excluded 
by  this  stream. 

The  polar  waters  are  also  felt,  but  to  a  less  extent,  on  the  borders  of 
northwest  Europe.  The  effect  is  manifest  also  along  the  east  Asiatic  coast, 
where,  as  the  map  shows,  the  isotherm  of  35°  extends  down  to  45°  N.,  and 
that  of  68°  even  down  to  15°  N. 

Deep-water  effects.  —  The  great  currents  of  the  ocean  have  also  deep- 
water  effects.  They  are,  as  has  been  shown,  deep-water  currents.  The  Gulf 
Stream  has  a  depth  of  2500  to  1800  feet  from  the  Florida  straits  to  Cape 
Hatteras,  and  1500  to  1000  north  of  the  cape  through  the  ocean ;  and  the 
effects  of  the  polar  currents  or  movements  are  of  all  depths  from  the 
surface  to  the  bottom.  Between  the  two  systems  of  movements,  that  of 
the  tropical  and  that  of  the  polar  waters,  the  ocean  derives  its  distribution 
of  heat.  South  of  Cape  Hatteras,  the  deeper  waters  of  the  Gulf  Stream 
give  warmth  to  the  bottom  over  a  belt  50  to  75  miles  wide ;  and  north  of 
this  cape,  the  warm  belt  lies  between  the  65-fathom  line  on  the  west,  where 
stands  the  cold  wall  of  the  Labrador  current,  and  the  200-fathom  line  on  the 
east ;  giving  a  temperature  of  53°  to  47°  (Verrill)  to  the  bottom,  while  on 


OCEANIC    AND    ATMOSPHERIC    MOVEMENTS    AND   TEMPERATURE.     49 

either  side  it  is  45°  or  less.  Further,  where  the  Gulf  Stream  strikes  the 
submarine  slopes  of  the  British  Islands,  it  gives  the  same  temperature  to 
the  bottom  in  depths  of  60  fathoms  or  less  to  600  or  700  fathoms;  and 
a  similar  cold  wall  exists  against  the  polar  waters  of  the  Norwegian  sea. 

But  through  the  breadth  of  the  oceans,  owing  to  the  polar  movement 
equatorward,  the  waters  at  a  depth  of  600  fathoms,  or  3600  feet,  have 
almost  everywhere  a  temperature  near  40°  F.,  or  from  42°  to  39£°  F. ;  and  at 
500  fathoms,  from  42°  to  45°.  Further,  at  1000  fathoms,  the  temperature  is 
usually  between  36°  and  40°,  and  32°  to  36°  at  2000  fathoms  and  below  to  the 
bottom.  The  deeper  part  of  the  north  Atlantic  has  a  bottom  temperature 
of  35°  F.  (about  34-3°-35-6°),  while  in  the  south  Atlantic  it  is  31°-34°  because 
the  south  Atlantic  has  a  more  open  polar  connection  (Carpenter).  In  both 
the  north  and  the  south  Atlantic  the  area  of  greatest  bottom  cold  is  very 
large  in  the  western  half  of  the  ocean  and  small  in  the  eastern,  the  ratio 
being  nearly  4  to  1.  In  the  Pacific,  the  Challenger  Expedition  found  bottom 
temperatures  of  34'6°  to  35*4°  in  both  the  north  and  south  Pacific,  with 
40°  F.  between  450  and  600  fathoms.  In  the  arctic  seas  the  bottom  temper- 
ature of  28°  F.  has  been  observed  as  the  extreme. 

Adjoining  seas,  like  the  Caribbean  and  the  Mexican,  have  for  their 
minimum  temperature  the  temperature  of  the  bottom  waters  of  the  straits 
connecting  them  with  the  ocean,  which,  in  the  case  of  the  seas  mentioned,  is 
39|°  F.  In  the  Mediterranean  Sea,  which  has  no  inflowing  cold  waters,  the 
temperature  below  600  feet  is  at  all  depths  54°  to  56°  F.  The  inflow  at 
the  Straits  of  Gibraltar  is  of  surface  Atlantic  waters,  and,  in  consequence 
of  the  very  abundance  of  evaporation  from  its  surface,  the  amount  of  it  is 
more  than  that  of  the  outflowing,  more  saline  and  therefore  heavier,  Medi- 
terranean waters. 

ATMOSPHERIC  CURRENTS  AND  TEMPERATURE.     MOIST  REGIONS 

AND  DESERTS. 

(1)  Heat-conditions  of  the  atmosphere.  —  The  amount  of  heat  absorbed  by 
the  atmosphere  from  the  sun's  rays  depends  largely  on  its  density  or  the  baro- 
metric pressure.  It  is  therefore  greater  at  the  sea  level,  where  the  pressure 
has  a  mean  of  29 '8  to  30  inches,  than  at  any  elevation  above  it  over  the  land. 
It  is  least  at  the  tops  of  the  mountains,  and  greatest  in  depressions  below 
tide  level,  like  that  of  the  Dead  Sea,  1390  feet  below,  and  the  Caspian, 
84  feet  below.  The  land  surface  receives  and  gives  out  heat,  and  is  an 
important  source  of  heat  to  the  air  which  derives  in  this  way  two  thirds  of 
its  temperature,  the  rest  being  due  to  absorption  of  the  sun's  rays.  The 
waters  of  the  ocean  also  absorb  heat,  but  this  takes  place  slowly ;  the  heat 
largely  becomes  latent,  and  it  is  also  distributed  below  by  convection ;  hence, 
under  the  same  exposure,  it  gives  much  less  heat  to  the  atmosphere  than  a 
land  surface.  Moreover,  lands  in  the  colder  latitudes  and  at  heights  become 
covered  with  snow,  while  the  ocean  has  no  ice-covering  except  near  coasts 
in  polar  latitudes. 

T) ANA'S   MANUAL —  4 


50  PHYSIOGRAPHIC   GEOLOGY. 

An  increase  of  density  from  an  addition  of  carbonic  acid  would  increase 
proportionally  the  amount  of  heat  absorbed,  the  absorptive  power  of  this 
gas  being  90  times  that  of  the  atmosphere.  The  presence  of  aqueous  vapor 
also  increases  the  absorptive  power. 

The  winds  are  a  means  of  distributing  heat  and  moisture,  and  thus  tend 
to  equalize  the  temperature  of  the  globe.  But,  at  the  same  time,  they  make 
local  areas  of  extreme  heat  and  cold,  of  extreme  precipitation  and  dryness. 

(2)  Surface  movements  of  the  winds.  —  For  theoretical  views  and  details 
on  this  subject,  reference  should  be  made  to  meteorological  treatises,  the 
remarks  here  being  confined  to  a  few  general  facts.     They  illustrate  well 
the  dependence  of  effects  on  the  east-west  characteristics  of  the  earth  derived 
from  its  rotation. 

In  general,  the  courses  of  the  winds  are  nearly  coincident  with  those  of 
the  great  oceanic  currents,  and  it  is  held  by  many  that  the  winds  are  the 
motive  power  of  the  currents.  In  the  tropics,  the  prevailing  course  of  the 
winds  is  from  the  eastward  (these  winds  being  called  the  trades),  and  in 
the  higher  temperate  latitudes  from  the  westward.  There  is  a  tendency  to 
calms  (1)  along  the  equator;  (2)  in  mid  ocean  between  the  parallels  of  25° 
and  35° ;  and  (3)  about  the  poles ;  but  the  equatorial  area  of  calms  is  some- 
times in  part  a  region  of  a  counter-current. 

The  trades  strike  the  east  side  of  the  continent,  and  then,  bending  away 
from  the  equator,  curve  around  to  become  the  westerly  winds.  And  the 
reverse  is  true  for  the  westerly  winds ;  but  where  they  strike  the  west  side 
of  a  continent,  only  part  of  the  wind  may  be  deflected  toward  the  equator 
and  the  rest  curve  around  poleward;  and  when  so,  the  former  gradually 
warms  up,  since  it  goes  toward  warmer  regions,  and  the  latter  loses  heat 
because  going  into  higher  latitudes.  These  two  parts  vary  in  their  rela- 
tive amounts  or  force  according  to  the  trends  of  the  coast-lines  or  form  of 
the  land. 

The  Indian  Ocean  makes  an  exception  under  the  system,  because  the 
region  there  existing  to  the  north  of  the  equator  is  occupied  by  a  continental 
mass,  Asia,  which  pushes  the  circuit  to  the  south,  the  winds  that  blow  there 
from  the  eastward  corresponding  to  the  trades  of  the  other  oceans. 

(3)  Distribution  of  moisture.  —  The  capacity  of  air  for  moisture  —  that  is, 
its  power  of  taking  up  moisture  without  a  loss  of  transparency  —  varies  with 
the  temperature.     When  saturated,  a  loss  of  heat  causes  condensation,  and 
thence,  mist,  clouds,  rain.     On  the  contrary,  an  increase  of  heat  increases 
capacity  for  moisture,  and  the  wind,  instead  of  dropping  moisture,  gathers 
moisture  from  the  surface  it  passes  over. 

In  the  south  Pacific  the  wind  from  the  west  is  a  cold  wind,  charged  with 

moisture  derived  from  the  ocean ;  as  it  divides  on  striking  South  America  it 

becomes  in  its  northern  branch  desert-making,  in  its  southern,  rain-giving. 

The  branch  going  north  passes  into  regions  of  increasing  warmth,  and  the 

vind  gathers  up  the  moisture  beneath  and   makes  the   desert   region   of 


OCEANIC   AND   ATMOSPHERIC   MOVEMENTS   AND   TEMPERATURE.     51 

Atacama,  and  a  dry  shore  region  northward  through  Peru ;  while  the  branch 
going  southward,  which  encounters  increasing  cold,  makes  one  of  the  wetter 
areas  of  the  globe,  Valdivia  having  an  annual  rainfall  of  115  inches.  The 
same  effects  of  the  two  branches  are  produced  on  the  western  border  of 
North  America,  the  western  border  of  north  Africa  and  Europe  ;  in  western 
south  Africa;  in  western  Australia.  (See  Eainfall  map  by  E.  Loomis, 
Amer.  Jour.  ScL,  III.,  xxiii.,  1882.) 

On  the  contrary,  the  wind  from  the  east  over  the  tropics  is  a  warm  wind 
charged  with  moisture.  After  striking  North  and  South  America  it  bends 
away  from  the  equator  into  cooler  latitudes,  and  makes  a  great  moist  region 
of  eastern  North  America,  and  of  eastern  South  America,  with  excessive 
moisture  over  large  areas ;  and  the  position  of  the  higher  mountain  range  of 
America,  far  toward  the  western  border,  lays  open  the  whole  interior  to  the 
moisture.  The  trade  winds  produce  a  similar  effect  on  the  eastern  side  of 
Eurasia  and  Australia,  making  the  border  of  China  one  of  the  wet  regions 
of  the  globe,  and  so  also  a  narrow  mountain  border  for  Australia. 

Mountains  have  cold  summits,  and  consequently  are  great  condensers  of 
moisture.  They  therefore  take  a  prominent  part  in  the  above  mentioned 
system  of  results,  and  also  produce  local  effects  in  other  regions. 

The  first  high  cold  land  struck  by  the  winds  takes  a  large  portion  of  the 
moisture  out  of  them  and  leaves  less,  or  little,  for  the  region  beyond.  And 
thus  robbed,  even  the  trades  may  become  dry  winds.  The  contrasts  are  well 
shown  on  the  opposite  slopes  of  the  Hawaiian  mountains  —  the  eastern 
receiving  much  rain  from  the  trades,  the  western  getting  almost  none.  For 
the  same  reason  the  interior  of  North  America  is  relatively  dry,  the  amount 
of  precipitation  over  the  Atlantic  border  being  40  to  50  inches  a  year,  and 
in  the  interior  20  to  40  and  less.  So  it  is  also  with  the  interior  of  South 
America  as  compared  with  the  coast  region  to  the  north ;  and  Sahara,  begun 
in  northwestern  Africa,  stretches  across  the  continent.  The  great  Desert  of 
Gobi  is  thus  shut  off  from  sea  winds,  and  winter  winds  blow  from  it  instead 
of  into  it.  The  higher  ridges  along  the  Rocky  Mountain  summit  raise 
locally  the  amount  of  precipitation,  but  it  falls  off  again  over  all  the  western 
slopes,  and  continues  very  small  to  the  Sierra  Nevada,  averaging  less  than 
10  inches  a  year  over  a  broad  belt  from  the  Great  Salt  Lake  region  to  the 
Gulf  of  California. 

It  is  apparent  from  the  facts  which  have  been  presented  that  the  conti- 
nents have  derived  many  of  their  individualizing  characteristics,  their  several 
diversities  of  surface,  climate,  and  life,  from  the  disposing  influence  of  the 
earth's  rotation.  This  is  strikingly  apparent  in  the  existing  flora  and  fauna, 
briefly  described  in  the  following  pages ;  it  becomes  still  more  evident  after 
a  review  of  the  succession  of  faunas  and  floras  in  the  earth's  history  in 
which  the  individual  features  of  each  continent  are  traced  back  far  toward 
"the  beginning." 

The  great  truth  is  taught  by  the  air  and  waters,  as  well  as  by  the  lands, 
that  the  diversity  about  us,  which  seems  endless  and  without  order,  is  an 


52  PHYSIOGRAPHIC   GEOLOGY, 

exhibition  of  perfect  system  under  law.  If  the  earth  has  its  barren  ice-fields 
about  the  poles,  and  its  deserts  no  less  barren  toward  the  equator,  they  are 
not  accidents  in  the  making,  but  results  involved  in  the  scheme  from  its 
very  foundation. 

V.     GEOGRAPHICAL  DISTRIBUTION  OF  PLANTS  AND   ANIMALS. 

The  geographical  distribution  of  plants  and  animals  is  dependent  on  both 
physical  and  biological  conditions. 

1.  Temperature  has  universal   influence.     Species   are   usually  confined 
within  narrow  temperature  limits.     They  differ  therefore  in  the  different 
zones  from  the  equator  to  the  poles,  some  having  a  range  of  only  a  few 
degrees,  and  others  of  half  a  hemisphere.     They  differ  also  with  the  height 
on  passing  from  the  sea  level  to  the  limit  of  life  (the  limit  of  perpetual 
snow)   about   the   summits  of  the  highest  mountains,  or  even  higher,  as 
regards  Microbes  or  Bacteria,  the  lowest  of  cryptogamous  plants,  the  only 
kinds  having  the  range  of  the  world.     They  also  differ  as  we  descend  in 
the  ocean. 

2.  Light  is  another  universal  cause.     Some  species  need  for  successful 
growth  and  reproduction  the  direct  rays  of  the  sun ;  others  are  confined  to 
shady  places,  dark  places,  and  very  dark  places,  like  caves;  some  to  the  surface 
waters  of  the  ocean,  because  of  the  light  that  penetrates  them,  and  others 
to  dark  depths.     A  lawn  will  have  a  rich  surface  of  grass  in  the  sunshine, 
and  become  full  of  weeds  under  the  shade  of   a  tree,  because  the  weeds 
flourish  in  the  shade,  while  the  grass  dwindles  and  becomes  crowded  out; 
and  in  such  a  case  fertilizers  may  help  only  the  weeds  instead  of  the  grass. 

3.  Difference  in  pressure,  —  This  cause  also  is  universal  in  its  action,  but 
very  feeble  in  its  effects.     The  atmospheric  pressure  near  the  earth's  surface 
diminishes  about  one  pound  per  square  inch  for  each  1900  feet  of  ascent,  or, 
approximately,  three  pounds  for  6000  feet.     In  the  ocean,  the  pressure  in- 
creases at  the  rate  of  about  one  pound  per  square  inch  for  each  2-2  feet  of 
descent,  or  2750  pounds  for  6000  feet  or  1000  fathoms,  and  11,000  pounds  for 
24,000  feet. 

But  marine  species  readily  become  adapted  to  all  pressures,  as  the  outside 
water  penetrates  them.  Twenty-six  fishes  are  known  to  have  a  range  of  5400 
feet,  and  some  macrural  Crustaceans  a  range  of  more  than  12,000  feet.  The 
Shrimp,  tiergestes  mollis,  for  example,  ranges  from  2238  to  17,694  feet. 

But  after  a  sudden  change,  or  when  brought  to  the  surface  in  a  dredge, 
a  fish  presents  "a  most  disreputable  appearance,"  the  swimming  bladder 
protruding  from  its  mouth,  the  eyes  forced  from  their  sockets,  and  the  scales 
fallen  off  (A.  Agassiz). 

4.  Differences  in  moisture  and  dry  ness  of  climate  are  great  sources  of  lim- 
itation in  the  range  of  species.     Differences  in  soil  have  wide  influence  ;  for 
a  soil  must  contain  the  materials  essential  to  a  plant's  growth  before  it  will 


GEOGRAPHICAL  DISTRIBUTION   OF   PLANTS   AND  ANIMALS.          58 

grow  in  it;  and  what  is  good  for  one  is  bad  for  another.  Rocks  favor 
certain  plants ;  and,  in  some  instances,  differences  in  rocks  adapt  them  to- 
different  species  of  Lichens  and  Mosses.  As  the  composition  of  the  air, 
earth,  or  water  varies,  the  inhabitants  differ,  what  is  death  to  one  being 
life  to  another. 

The  general  principle  that  all  living  species  must  have  food  and  just  the 
food  they  need,  or  die,  is  one  of  the  foundations  for  the  differences  in  lim- 
itation under  all  the  causes  above  mentioned.  Geological  changes  that  vary 
these  conditions  have  therefore  been  a  great  means  of  determining  distribu- 
tion, by  varying  temperatures,  climate,  and  land  level ;  by  varying  soils  and 
converting  deserts  into  dry  land,  marshes,  or  seas  by  joining  lands  through 
change  of  level,  so  as  to  favor  or  compel  migration ;  or  sinking  them,  to  the 
extermination  of  species.  In  addition,  as  Darwin  has  shown,  the  changes 
brought  about  in  the  associations  of  species,  in  these  ways  and  through  their 
mutual  dependence  as  to  food  and  all  necessities,  have  been  other  ceaseless 
causes  of  variation  in  distribution.  Those  continental  lands  that  are  most 
isolated,  like  Australia  and  South  America,  have,  for  the  reasons  mentioned, 
and  others,  the  largest  number  of  peculiar  species,  and  hence  the  most 
homogeneous  population. 

BRIEF  REVIEW  OF  DISTRIBUTIONAL  FACTS  OF  GEOLOGICAL  INTEREST. 

TERRESTRIAL  SPECIES. 
1.    Plants. 

Plants  of  the  land  spread  to  all  heights,  even  above  the  snow-limit.  Among  Cryp- 
togams, Ferns  and  Lycopods  flourish  in  all  latitudes  from  the  equator  to  the  polar  lati- 
tudes ;  but  Tree  Ferns,  not  beyond  the  parallel  of  35°.  Under  the  warm  moist  climates  of 
tropical  and  warm-temperate  latitudes,  Ferns  and  Lycopods  grow  in  greatest  numbers  and 
luxuriance.  Palms  have  their  limit  in  South  America  in  latitude  36°,  in  North  America 
and  Australia  in  35°,  and  in  Asia  in  34°;  in  Europe  one  species,  Chamcerops  humilis, 
extends  as  far  north  as  latitude  44°. 

The  Conifers  range  through  all  zones.  The  Yews,  as  Salisburia,  live  in  warm-temper- 
ate latitudes.  But  the  subdivision  of  Cycads  is  confined  to  tropical  and  warm-temperate 
latitudes.  They  occur  in  southern  Asia,  Japan,  the  East  Indies,  Madagascar,  Australia, 
southern  Africa,  and  tropical  America,  including  Mexico  and  the  West  Indies. 

2.    Animals. 

Australian  characteristics.  —  Australia,  although  near  the  East  India  Islands,  is 
remarkable  for  the  absence  of  all  ordinary  or  placental  Mammals  except  Bats  of  the  genus 
Pteropus,  Rats,  and  Mice.  Instead,  it  has  a  large  population  of  Marsupial  Mammals,  the 
diversified  types  of  ordinary  Mammals  being  represented  under  the  Marsupial  or  pouched 
structure.  Wallace,  in  allusion  to  the  diversity  among  them,  says  (Geogr.,  i.  391)  : 
"Some  are  carnivorous,  some  herbivorous;  some  arboreal,  some  terrestrial;  there  are 
insect-eaters,  root-gnawers,  fruit-eaters,  honey-eaters,  leaf  or  grass-feeders.  Some  are  like 
wolves  in  habits,  others  like  marmots,  weasels,  squirrels,  flying-squirrels,  dormice  or  jer- 
boas. All  are  members  of  one  stock,  and  have  no  real  affinity  with  the  Old- World  forms, 
which  they  often  outwardly  resemble."  Besides  Marsupials,  which  are  sometimes  called 
semi-oviparous,  there  are  the  still  inferior  Monotremes,  the  Duck-bill  and  Echidna,  both 
of  which  are  strictly  oviparous,  although  true  Mammals  inasmuch  as  they  suckle  their 


54  PHYSIOGRAPHIC   GEOLOGY. 

young.  The  Australian  region  (which  includes  also  New  Guinea,  Celebes,  and  some 
islands  just  west)  has  also  numerous  Amphibians,  more,  says  Wallace,  than  any  other 
continent  except  South  America,  and  but  few  Reptiles.  It  is  also  noted  for  its  number  of 
species  of  Pigeons,  two  fifths  of  all  that  are  known  being  confined  to  it ;  for  its  King- 
fishers, the  fauna  embracing  three  fourths  of  all  kinds  living  ;  for  Birds  of  Paradise,  Lyre 
Birds  (the  Menurids),  its  many  Parrots,  those  of  the  Australia-Malay  area  comprising 
176  species  ;  and  under  the  Ostrich  type,  its  Cassowaries  (genus  Casuarius)  of  11  species, 
and  Emeus  (Dromseus)  of  2  species. 

New  Zealand,  which  is  also  a  part  of  the  Australian  region,  has  2  Bats  for  its  only 
Mammals ;  the  Apteryx,  among  its  Birds ;  a  single  Frog  among  Amphibians ;  a  dozen 
Lizards  ;  a  Reptile  of  palaeic  characteristics,  the  Hatteria  or  Sphenodon,  which  has  but  1 
species  (S.  punctatum),  the  last  of  an  otherwise  extinct  tribe,  the  Rhynchocephalidse.  It  is 
very  poor  in  Insects,  having  only  11  species  of  Butterflies,  with  about  300  Coleopters 
(Wallace).  Besides  these,  there  were,  one  or  two  centuries  or  farther  back,  the  now 
extinct  birds,  Dinornis,  Palapteryx,  and  many  others  of  Ostrich- like  character.  On 
Chatham  Island,  500  miles  east  of  New  Zealand,  but  within  what  may  be  called  New  Zea- 
land seas,  there  have  been  found  the  remains  of  a  flightless  bird  akin  to  those  of  New 
Zealand. 

The  Oriental  region,  including  India  and  eastward  to  southern  Japan,  with  Sumatra, 
Java,  Borneo,  etc.  —  This  tropical  region,  directly  north  and  northwest  of  the  Australian, 
is  wonderfully  different  from  it.  There  are  no  Marsupials  or  Monotremes ;  but  instead 
Mammals  of  other  kinds,  Man-apes,  as  the  Orang-outang,  and  Lemurs,  Lions,  Tigers, 
Hyenas,  Bears,  Elephants,  Rhinoceroses,  Manis  among  Edentates,  and  among  Reptiles, 
Crocodile  and  Gavials. 

The  African  or  Ethiopian  region,  including  the  part  of  Africa  south  of  the  Atlas 
Mountains,  with  Madagascar  and  the  Mascarene  Islands.  —  The  Ethiopian  region  com- 
prises in  its  fauna  the  Hippopotamus,  Rhinoceros,  Camelopard,  Elephant,  Lion,  Hyena, 
a  characteristic  type,  Hyrax,  Horses  (Zebras),  the  Orycteropus  and  Manis  (Ant-eaters) 
among  Edentates  ;  the  Hedgehog  among  Insectivores ;  Anthropoid  Apes,  as  the  Gorilla, 
besides  other  Quadrumana  (all  of  which  have  32  teeth,  like  Man),  and  also  many  Lemurs ; 
but  no  Camels,  or  Bears,  or  Deer,  or  Oxen,  or  species  of  Sus  (Pig).  It  has  among  its 
Birds  two  species  of  Ostrich  of  the  genus  Struthio. 

Madagascar  not  long  since  had  its  JEpyornis,  related  to  the  Dinornis  of  New  Zealand 
and  the  Mascarene  Islands,  the  Dodo  (Didus  ineptus},  and  other  birds  now  extinct. 
Madagascar  is  noted  also  for  its  Lemurs,  of  which  there  are  35  species. 

The  South  American  or  Neotropical  region,  comprising  South  America,  the  West 
Indies  and  Central  America,  and  Mexico.  — The  Neotropical  region  is  remarkable  for  the 
number  of  peculiar  families  and  genera.  They  embrace  Monkeys  with  prehensile  tails, 
that  have  a  molar  tooth  more  in  each  jaw  than  those  of  Africa  ;  Tapirs  ;  Llamas,  Vicuna 
and  Guanaco,  of  the  Camel  family  ;  Dicotyles,  or  Peccary,  among  Wild  Boars  ;  Ant- 
eaters,  Sloths,  and  Armadillos  among  Edentates ;  Marsupials,  in  which  it  is  related 
to  the  Australian  region.  Among  Birds,  there  are  in  America  all  the  Humming  Birds  of 
the  world,  some  400  species  in  more  than  100  genera,  having  a  range  from  Patagonia 
to  Sitka  ;  Parrots,  numbering  141  species  ;  Toucans  ;  the  Rhea,  of  the  Ostrich  family  — a 
family  confined  to  the  three  southern  continents,  Australia,  Africa,  and  South  America ; 
among  Reptiles,  Alligators,  Crocodiles,  and  many  Amphibians,  being  next  to  Australian 
in  their  number  and  variety ;  and  among  Fishes,  the  Lepidosiren,  related  to  the  Dipnoi 
of  Africa  and  Australia. 

Within  this  region  the  West  India  Islands  are  remarkable,  like  some  of  the  Hawaiian 
Islands  in  the  Pacific,  for  the  number  of  their  land-shells,  numbering  608  species  of 
Operculates  and  737  of  Inoperculates.  The  number  of  the  former  in  South  America  is 
151,  of  the  latter  1251. 


GEOGRAPHICAL   DISTRIBUTION   OF   PLANTS   AND   ANIMALS.          55 

The  Nearctic  region,  or  the  North  American,  from  Mexico  northward,  excluding  the 
West  India  Islands.  —  Of  peculiar  types  there  are  among  Mammals  the  Marsupial  of  the 
genus  Didelphys,  successor  to  genera  that  extend  far  back  in  American  geological  history  ; 
among  Reptiles,  which,  however,  are  more  properly  neotropical,  the  Alligator ;  among 
Fishes,  the  Ganoids,  which  extend  south  to  Mexico  and  Cuba ;  the  Humming  Birds,  (only 
six)  ranging  up  from  South  America ;  and  the  fresh-water  Mollusks,  in  which  this  region 
"surpasses  all  other  parts  of  the  globe." 

The  Palearctic  or  Eurasian,  north  of  the  Atlas  Mountains  of  Africa,  and  including 
Persia,  the  region  of  the  Himalayas  and  northern  Japan. — This  great  region  has  its 
Monkeys  of  the  African  genus  Macacus  at  Gibraltar  and  north  Africa,  in  Tibet  and 
north  China ;  its  Camels,  ranging  from  Sahara  to  Mongolia  and  Lake  Baikal ;  Horses 
(Asses)  ;  its  Bovidse  (Cattle),  of  which  there  are  more  kinds  in  the  Old  World  than  in  the 
New  ;  the  Hyrax,  a  genus  occurring  in  Syria  as  well  as  in  Ethiopia  ;  the  Beaver  ( Castor 
fiber),  near  the  Castor  canadensis  of  North  America. 

AQUATIC  SPECIES. 

Contrary  to  old  ideas,  the  bottom  of  the  ocean  abounds  in  life  through  all  depths,  down 
to  3000  fathoms,  and  has  its  species  even  to  a  much  greater  depth.  And  along  the 
bottom,  from  Arctic  to  Antarctic  seas,  there  is  a  highway  nearly  as  broad  as  the  ocean, 
where  the  temperature  is  not  above  40°  F.  or  below  28°  F.,  and  by  this  highway  species 
befitting  those  depths  can  migrate  the  world  over. 

Limitation  in  distribution  along  shores  depends  much  on  the  kind  of  bottom,  whether 
rocky,  or  sandy,  or  muddy ;  on  the  quality  of  the  water,  whether  pure  or  impure,  or 
encroached  upon  by  fresh  waters  from  the  discharge  of  rivers.  But  the  two  chief 
sources  of  limitation,  both  along  shores  and  throughout  the  depths,  are  temperature 
and  amount  of  light. 

The  surface  distribution  of  temperature,  as  illustrated  by  the  temperature  chart,  has 
been  explained  on  page  45.  The  isothermal  line  of  68°  is  the  boundary  of  the  coral- 
reef  seas.  Within  the  area,  and  for  the  most  part  between  the  parallels  of  29°  north  and 
south,  the  reef-making  Corals  abound.  Part  of  the  species  require  its  warmer  portions ; 
the  hardier  extend  to  its  borders.  By  following  the  outline  of  the  area  it  may  be  seen, 
where  reef  Corals  can  grow,  and  from  what  coasts  of  the  Atlantic  and  Pacific  reefs  they 
are  excluded  by  the  coolness  of  waters  ;  and  also  why  the  Bermudas  are  within  the  coral- 
reef  limit,  although  situated  in  latitude  32 }°  N. 

It  will  also  be  observed  that  in  the  Atlantic  Ocean  the  meeting  of  the  isotherms  of 
56°,  62°,  and  68°  at  Cape  Hatteras  signifies  that  two  temperate  zones,  the  temperate  and 
subtemperate,  which  have  great  expansion  on  the  European  side  of  the  ocean,  and  even 
include  the  whole  Mediterranean  Sea,  with  its  very  abundant  life,  are  wholly  excluded 
from  American  waters  because  of  the  meeting  at  that  point  of  the  Labrador  and  Gulf- 
Stream  currents  (page  46),  and  thereby  of  zones  of  Labrador  and  Gulf-Stream  species. 
The  chart  thus  explains  many  strange  facts  in  the  distribution  of  the  life  along  the 
borders  of  the  ocean. 

The  second  cause  of  limitation  is  the  amount  of  light,  as  explained  by  Fuchs.  It  has 
its  effects  at  120  to  180  feet,  and  more  marked  at  420  to  480  feet.  The  greatest  depth  at 
which  gelatine  bromide  photographic  plates  were  sensible  to  light  in  experiments  in  the 
Gulf  of  Nice  was  400  meters  (1312  feet);  350  meters  for  eight  hours  of  the  day;  300 
meters  from  sunrise  to  sunset ;  and  in  Lake  Geneva,  the  greatest  depth  200  meters  (Fol 
and  Sarrasin).  It  is  generally  held,  however,  that  there  can  hardly  be  a  total  absence  of 
light,  even  at  abyssal  depths,  since,  while  many  animal  species  are  blind,  or  have  eyes 
excessively  large  or  excessively  small,  many  others  have  them  of  normal  size  and  struc- 
ture. The  phosphorescence  of  various  species  among  Fishes,  Crustaceans,  Annelids, 
Ophiurans,  Ascidians,  Gorgonias,  Antipathes,  Medusae,  as  well  as  Infusoria,  may  be  all 


56  PHYSIOGRAPHIC   GEOLOGY. 

there  is  of  light  at  abyssal  depths  ;  but  this  is  not  probable.  Murray  observes  that  the 
eyes  of  the  Fishes  are  in  general  unusually  large  at  depths  of  480  to  1200  feet ;  but 
beyond  this  depth,  small-eyed  species  as  well  as  large-eyed  are  common,  and  many  also 
are  blind. 

The  Littoral  zone. — By  means  of  light,  rather  than  temperature,  the  limits  of  the 
Littoral  zone  are  determined.  Reef-forming  Corals,  and  therefore  coral-made  reefs,  have 
their  limit  in  depth  at  120  or  150  feet  in  the  equatorial  regions,  and  at  90  to  96  feet  near 
the  border  of  the  coral-reef  seas ;  and  since  the  temperature  of  68°  F.  in  the  tropics  is 
usually  600  feet  below  the  surface,  light  is  made,  by  Fuchs,  to  be  the  chief  cause.  A 
vast  variety  of  species  are  congregated  under  like  limitation,  the  coral-reef  seas  being 
uthe  gathering  grounds  of  an  extremely  rich  fauna,"  says  Fuchs,  and  one  so  peculiar  that 
the  terms  coral-fishes,  coral-mollusks,  and  the  like,  would  not  be  inappropriate ;  a  fauna 
that  embraces  "  the  whole  splendor  of  the  animal  life  "  of  the  Indian  and  Pacific  oceans. 
Within  this  Littoral  zone  belong,  moreover,  the  areas  of  large  Bivalves,  such  as  Oysters, 
Pearl  Oysters,  Scallops,  which  have  their  maximum  development  in  from  48  to  60  feet, 
and  are  not  found  below  120  feet.1 

The  seaweed  areas  reach  to  a  depth  of  30  fathoms,  or  about  200  feet.  Plants  are 
dependent  on  light  for  assimilation,  and  hence  comes  this  narrow  limit  for  the  aquatic  part 
of  the  vegetable  kingdom. 

The  Fucoids  and  strap-like  Laminarians,  or  the  brown  and  olive  Seaweeds  —  related, 
it  is  supposed,  to  the  Seaweeds  of  early  time,  when  no  seas  were  colder  than  those  of  the 
modern  temperate  zone  —  live  now  on  most  shores  from  the  tropics  to  the  poles,  and  attain 
their  greatest  size  in  the  colder  latitudes. 

The  only  deep-water  plants  thus  far  observed  are  Corallines  at  900  feet,  and  small 
Algae,  found  to  bore  into  corals  that  came  up,  according  to  Duncan,  from  a  depth  of  6000 
feet. 

The  depths.  —  Below  420  to  480  feet  are  the  regions  of  darkness.  They  are  divided 
locally  into  two  sections,  a  warm  and  a  frigid,  by  the  Gulf  Stream  and  other  tropical 
currents.  The  depth  to  which  the  warm  waters  of  this  stream  extend  along  the  borders 
of  the  Atlantic  basin,  and  thence  across  the  ocean  to  Great  Britain,  are  mentioned  on 
page  5.  Where  these  waters  wash  the  sides  of  the  Atlantic  basin  from  Florida  north- 
eastward, there  is  a  profusion  of  life  of  all  marine  kinds ;  and  the  same  is  true  for  the 
area  within  the  British  sea. 

The  cold  belt  passes  close  by  the  western  side  of  the  warm  belt  off  New  Jersey  and 
Nantucket.  The  commingling  of  the  two  in  a  storm  is  stated  by  Professor  Verrill  (1882) 
to  have  probably  caused  the  extermination  —  only  temporary,  it  has  proved  — of  a  large 
food-fish,  the  Tile-fish,  of  the  genus  Lopholatilus,  which  was  caught  abundantly  by  a  Fish 
Commission  expedition  in  1881  off  Nantucket  with  a  trawl  at  a  depth  of  420  to  900  feet. 
During  the  following  winter  great  numbers  of  the  dead  Tile-fish  were  seen  by  passing 
vessels,  floating  at  the  surface ;  and  in  the  dredging  of  1882  over  the  same  area  not  one 
was  obtained ;  and  many  other  species  dredged  in  1881  were  missing  in  1882.  In  1890 
the  Tile-fish  was  again  found. 

The  bottom  of  the  ocean  through  all  its  depths  is  constantly  receiving  contributions  of 
the  hard  parts  of  its  living  species,  from  the  bones  of  Whales  and  Sharks  to  the  siliceous 
shells  of  Diatoms,  and  the  calcareous  of  Rhizopods.  It  is  often  difficult  to  determine  for 
the  smaller  species  whether  they  are  denizens  of  the  dark  depths  or  of  more  superficial 
waters.  Most  of  the  pelagic  species  that  are  found  abundantly  at  the  surface  of  the 
ocean  during  the  dark  hours  of  the  night,  and  may  then  be  easily  taken  with  a  hand-net, 
go  to  greater  depths  during  the  day,  showing  that  they  are  really  part  of  the  fauna  of  the 
darkness.  Pelagic  species,  according  to  Agassiz,  are  mostly  confined  to  within  1200  feet 
of  the  surface. 

1  J.  Fuchs,  Geol.  Verhandl.  Reichanstalt,  No.  4,  1882;  Ann.  Mag.  N.  Hist.,  January,  1883. 


GEOGRAPHICAL  DISTRIBUTION   OF   PLANTS   AND  ANIMALS. 


57 


Oceanic  species  include  a  large  part  of  Diatoms  or  silica-secreting  microscopic  plants. 
They  live  near  the  surface,  requiring  light  like  other  plants,  and  are  forced  to  keep  near 
the  surface  by  the  bubble  of  oxygen 
they  give  out  in  assimilation.  They 
abound  especially  in  the  southern  At- 
lantic, and  great  areas  over  the  bottom 
are  covered  with  a  Diatom  ooze  or  soft 
mud. 

The  Foraminifers,  or  calcareous 
Rhizopods,  are  solely  salt-water  spe- 
cies. They  in  part  live  near  the  sur- 
face, if  not  altogether.  These  abound 
in  many  seas,  excepting  the  more  frigid, 
and  make  by  their  accumulation  at  the 
bottom  the  Globigerina  ooze,  even  to 
depths  of  174,000  feet.  Maury,  al- 
luding to  the  dropping  to  the  ocean's 
bottom  of  the  Foraminifers,  says : 
"The  sea,  like  the  snow-cloud  with 
its  flakes,  in  a  calm  is  always  letting 
fall  on  its  bed,  showers  of  microscopic 
shells,  and  all  pelagic  life  adds  to  the 
showers." 

Radiolarians,  or  siliceous  Rhizo- 
pods, occur  only  in  salt  water.  They 
are  abundant  in  some  localities  in  the 
central  Pacific,  at  a  depth  of  15,000 
feet  and  less.  They  make  a  Radio- 
larian  ooze.  A  Radiolarian  deposit  on 
the  Barbadoes  is  supposed  to  indicate 
an  elevation  of  the  sea-bottom  of  1000 
to  2000  feet. 

Siliceous  Sponges  occur  in  the 
ocean  at  various  depths  to  15,000  feet, 
and  from  warmer  temperatures  to 
40°  F.  The  Hexactinellids  are  most 
abundant  at  depths  of  80  to  100  fath- 
oms, at  which  depth  the  Euplectella 
(Fig.  29)  was  obtained  near  the  Philip- 
pines, in  waters  at  a  temperature  of 
69°  F.,  and  near  Cebu,  of  69°  F.  For 
figures  of  a  number  of  Sponge  Spicules 
see  page  432.  The  Choristid  Sponges 
occur  down  to  16,200  feet,  and  the 
Lithistids  to  900  feet.  The  Sponges 
with  calcareous  spicules  or  skeleton 
are  also  widely  distributed.  Both  the 
calcareous  and  siliceous  also  occur  in 
shallow  waters,  fresh  and  salt. 

The   ordinary   or   the  Actinozoan  Euplectella  speciosa,  or  Glass  Sponge. 

Corals  are  all  marine.     Solitary  kinds 

extend  to  great  depths,  and  one  species,  Bathyactis  symmetrica,  has  a  vertical  range 
from  180  to  17,400  feet  (Moseley).    They  are,  therefore,  species  of  all  temperatures  and 


58 


PHYSIOGRAPHIC   GEOLOGY. 


30. 


Pentacrinus  decorus,  of  Carpenter.    From  A.  Agassiz. 


GEOGRAPHICAL  DISTRIBUTION   OF  PLANTS   AND  ANIMALS. 


59 


degrees  of  light  or  darkness.     Of  reef -making  Corals,  or  those  that  grow  in  plantations, 
an  account  has  already  been  given. 

Echinoderms  are  solely  marine  species,  and  they  are  found  at  all  depths  and  tempera- 
tures. Crinoids  of  the  genus  Pentacrinus  (Fig.  30,  page  58),  and  allied  to  Liassic  kinds, 
with  species  of  Rhizocrinus,  Bathycrinus,  etc.,  live  at  depths  above  100  fathoms  to  below 
1000,  many  where  the  temperature  is  below  40°  F.  Sea-urchins  (Echinids)  of  the  Cidaris, 
Diadema,  and  Ananchytes  families,  related  to  Cretaceous  types,  occur  at  similar  cold 
depths.  A.  Agassiz  states  that  the  deep-sea  fauna  of  the  West  Indies  includes  5  Jurassic 
genera  of  Echinids,  10  Cretaceous,  24  early  Tertiary,  and  4  of  the  later  Tertiary. 

Brachiopods  of  the  Terebratulid  type,  much  like  Oolitic  and  Cretaceous  forms,  occur  at 
all  depths,  down  to  18,000  feet ;  and  Discina,  from  the  surface  to  cold  depths  exceeding 
12,000  feet,  but  the  most  below  3000  feet ;  Crania,  at  600  to  1200  feet.  Lingula  occurs  in 
shallow  waters.  Species  of  the  genera  Atretia,  Discina,  and  Waldheimia  and  others  occur 
beneath  the  Gulf  Stream  at  depths  of  9000  to  9600  feet. 

Under  Mollusks :   Pteropods  are  pelagic  species,  and  live  mostly  near  the  surface. 
Their  shells  occur  in  large  numbers  in  the  bottom  deposit  at  depths  mostly  from  600  to 
1500  fathoms  in  the  West  Indies  and  some  parts  of  the  Pacific. 
The  form  in  Fig.  31  of  a  Mexican  Gulf  and  Atlantic  species 
is  much  like  that  of  many   ancient  Pteropods.     Deep-sea 
Gastropods  are  usually  small.     The  genus  Pleurotomaria  has 
only  four  living  species  known  ;  and  P.  Adansoniana  lives  at 
a  depth  of  1200  feet.    Trigonia  is  a  shallow-water  genus.    The 
Nautilus,  the  last  of  the  Cephalopods  having  external  shells, 
is  restricted  to  tropical  and  sub-tropical  seas. 

Among  Worms,  the  Serpulidse  occur  at  great  depths, 
species  having  been  obtained  by  the  "  Challenger  "  at  depths 
of  nearly  18,000  feet. 

Some  of  the  abyssal  species  of  Crustaceans  have  been 
shown  to  range  from  pole  to  pole.  The  large  spiny  crabs 
of  the  genus  Lithodesare  probably  among  them.  One  of  the 
species,  L.  Agassizii,  from  a  depth  of  1000  fathoms  under- 
neath the  Gulf  Stream,  is  reported  by  Verrill  (1884)  as  over 
three  feet  broad.  Many  of  the  deep-sea  Crustaceans,  accord- 
ing to  S.  I.  Smith,  are  remarkable  for  the  large  size  of  their 
eggs.  In  some  of  the  Eupaguri  (Soldier-crabs),  the  eggs  are 
8  times  the  usual  size  (volume) . 

The  only  surviving  species  of  the  Trilobite  and  Eurypterid 
line  are  two  of  the  genus  Limulus,  —  one  in  eastern  North 
America,  and  the  other  in  the  China  seas.  Crustaceans  are 
found  mostly  at  depths  less  than  3000  feet ;  2  only  out  of 
100  Brachyurans  dredged  off  the  United  States  were  from 
depths  greater  than  3000  feet ;  but  30  out  of  60  Macrurans 
were  from  greater  depths,  13  of  them  from  below  6000  feet, 
and  some  at  depths  of  12,000  feet ;  and  one  gigantic  blind 
species,  Phoberus  ccecus,  is  over  2  feet  long.  One  Isopod, 
Bathynomus  giganteus,  occurs  eleven  inches  long;  in  com- 
pensation for  dark  depths  it  has  compound  eyes  comprising 
4000  facets  (Milne-Edwards). 

Fishes.  —  The  existing  Ganoids  —  Sturgeons  included  — 
live  only  in  fresh  waters,  and  are  confined  to  America,  Africa, 

and  Australia.  North  America  has  3  species  of  the  genus  Lepidosteus,  and  Africa  2  of 
Polypterus  ;  and  of  the  related  Dipnoi,  which  are,  as  the  name  implies,  two-way  breathers, 
they  having  lungs  as  well  as  gills,  Queensland,  northern  Australia,  has  2  species  of  Cera- 


Pteropod,  genus  Styliolt 
A.  Agassiz. 


x5. 


60  PHYSIOGRAPHIC   GEOLOGY. 

todus,  and  South  Africa  has  1  species  of  Protopterus  :  in  all  not  a  dozen  species  of  a  tribe 
that  was  once  very  prominent.  Pelagic  fishes  occur  at  all  depths  to  nearly  18,000  feet. 
The  "  Albatross"  brought  up  a  Cyclothone  from  a  depth  of  17,694  feet  (Agassiz).  The 
species  of  the  deeper  waters  are  described  as  having  the  bones  feebly  calcareous,  being 
slender  and  loosely  connected,  and  some  species  will  take  in  a  fish  for  food  three  times  as 
large  as  themselves.  Many  kinds  are  phosphorescent. 

Cestraciont  Sharks,  once  very  numerous  in  species,  are  now  but  4  in  number,  and  all 
are  of  one  genus,  Cestracion.  These  are  confined  to  the  coast  regions  between  Japan  and 
Australia  or  New  Zealand.  The  type  has  therefore  nearly  reached  extinction. 

From  the  facts  reviewed  with  regard  to  marine  life,  it  is  apparent  that  the  knowledge 
of  depths  and  temperatures  of  living  species  affords  little  help  for  conclusions  about  the 
habits  of  ancient  species.  Many  of  the  tribes  that  were  represented  by  warm-water 
species  and  those  of  shallow  seas,  have  now  species  that  have  become  accustomed  to  great 
depths  and  cold  temperatures.  Modern  Brachiopods  are  no  criterion  for  the  ancient ;  nor 
modern  Crinoids,  nor  modern  Corals. 

Hot-water  Life. 

In  the  north  point  of  Owen's  Valley,  California,  according  to  Dr.  H.  C.  Wood  (Am. 
Jour.  Sci.,  1868),  at  120°  F.,  and  also  at  160°  F.  (as  learned  from  Mrs.  Partz) ,  occur  Algse, 
some  growing  to  a  length  exceeding  2  feet.  The  species  is  named  Nostoc  calidarium.  At 
the  Hot  Springs  ("  Geysers"),  on  Pluton  Creek,  California,  Professor  William  H.  Brewer 
observed  Confervae  in  waters  heated  to  140°-149°  F. ,  and  simpler  Algae  where  the  tem- 
perature was  200°  F.  At  the  same  place,  Dr.  James  Blake  found  2  kinds  of  Confervas 
in  a  spring  of  the  temperature  of  198°,  and  many  Oscillatoriae  and  2  Diatoms,  in  one  of 
174°.  In  the  waters  of  Pluton  Creek,  of  112°  F. ,  the  Algse  formed  layers  3  inches  thick. 
Dr.  Blake  also  collected  50  species  of  Diatoms  from  a  spring  in  Pueblo  Valley,  Nevada, 
the  temperature  being  163°  F.  ;  and  they  were  mostly  identical  with  those  of  beds  of 
infusorial  earth  in  Utah.  At  San  Bernardino,  California,  William  P.  Blake  found  living 
Confervae  in  water  at  a  temperature  of  130°.  At  Camiguin  Island,  east  of  Cebu,  Moseley 
found  living  Algae  at  113^°  F.  ;  and  W.  T.  T.  Dyer  has  reported  that  Oscillatoriae  have 
been  observed  growing  at  178°  to  182°  F. 

The  various  hot  springs  of  the  several  Geyser  Basins,  in  the  Yellowstone  National  Park, 
contain  very  various  Confervoid  forms.  The  hottest  springs,  up  to  200°  F.,  contain  numer- 
ous long,  slender,  white  and  yellow  vegetable  fibers,  of  undetermined  relations,  waving  in 
the  boiling  eddies,  and  becoming  buried  in  the  siliceous  deposits  over  the  bottom,  where 
they  often  form  layers  several  inches  thick.  The  bright  green  forms  appear  to  be  confined 
to  lower  temperatures.  W.  R.  Taggart  reports  that,  at  the  vents  on  the  shores  of  Lewis's 
Lake,  leafy  vegetation  is  limited  to  temperatures  below  120°  (Hayden's  Reports,  1871-2). 
Dr.  Josiah  Curtis  found,  in  these  hot  springs,  siliceous  skeletons  of  very  numerous  Dia- 
toms ;  but  the  vegetable  matter  was  wanting  in  all  cases  where  the  temperature  exceeded 
96°  F.  So  many  different  causes  might  introduce  these  skeletons  to  the  hotter  pools,  that 
their  presence  has  not  necessarily  any  more  significance  than  that  of  the  Grasshoppers  and 
Butterflies  which  are  frequently  found  in  the  same  pools.  —  Of  animal  life,  living  larves 
of  Helicopsyche  were  found,  by  Mr.  Taggart,  in  a  spring  having  the  temperature  of  108°, 
into  which,  however,  they  might  have  crawled  from  the  river,  which  was  close  by ;  so  that 
the  eggs  were  not  necessarily  laid  at  the  temperature  given. 

At  Banos,  on  Luzon,  Philippine  Islands,  the  author  observed  feathery  Confervae  in 
waters  heated  to  160°  F.  In  springs  in  the  Pass  of  Chivela,  having  a  temperature  of 
98°  F.,  the  United  States  Exploring  Expedition  of  1872  found  Fish;  and,  according  to 
Mr.  James  Richardson,  Fish  occur  in  springs  in  Marocco  having  a  temperature  of  75°  F. 

On  the  subject  of  the  geographical  distribution  of  animals,  the  most  important  works 
are  Wallace's  work  in  2  volumes  under  this  title,  and  his  Island  Life;  and  on  North 
America,  J.  A.  Allen,  1892,  Bulletin  American  Museum,  New  York. 


PART    II. 


STRUCTURAL    GEOLOGY. 

THE  earth,  separate  from  its  water  and  air,  —  that  is,  the  lithosphere,  as  it 
is  sometimes  called,  —  is  made  up  of  rock-material,  and  the  portions,  whether 
masses  or  beds,  which  come  under  geological  study,  are  termed  terranes. 
Structural  Geology  treats  of  the  mineral  constituents  of  terranes;  of  the 
rocks  which  the  minerals  form ;  and  of  the  structure  and  general  arrange- 
ment or  positions,  and  other  characteristics  of  terranes.  Some  terranes, 
though  unconsolidated,  in  a  general  way  come  under  the  head  of  rock- 
deposits  ;  for  consolidation  is  an  incident  that  may  or  may  not  take  place. 

The  subdivisions  of  Structural  Geology  as  here  adopted  are :  — 

I.    Rocks  :  their  constituents  and  kinds. 

II.  Terranes  :  their  constitution,  characteristics,  positions,  and  arrange- 
ment. 

I.    ROCKS:    THEIR   CONSTITUENTS  AND  KINDS. 

THE  ELEMENTS,  AND  THEIR  SIMPLER  COMBINATIONS. 

The  number  of  elements,  or  substances,  not  yet  shown  to  be  compound, 
that  have  been  obtained  from  the  earth's  rocks  and  minerals  is  70.  Of 
these,  oxygen,  nitrogen,  hydrogen,  chlorine,  and  fluorine,  at  the  ordinary 
temperature  and  pressure,  are  gases.  A  few  facts  are  here  stated  respecting 
the  elements  of  most  geological  importance. 

Oxygen.  —  Oxygen  is  the  most  abundant  element.  It  constitutes  88-89 
per  cent  by  weight  of  water,  21  of  the  atmosphere,  and  about  50  of  all  other 
material  in  the  earth's  structure.  It  owes  its  importance  in  nature  to  the 
intensity  of  its  chemical  attraction  for  nearly  all  the  elements.  Ordinary 
combustion  of  wood,  coal,  or  gas  is  due  to  the  combination  of  its  elements 
with  oxygen ;  and  living  growth  is  dependent  on  the  same  process. 

Combined  with  (1)  hydrogen,  oxygen  forms  water,  H20 ;  with  (2)  potassium 
(called  also  kalium},  potash,  K20 ;  with  (3)  sodium  (natrium),  soda,  Na20 ; 
with  (4)  lithium,  lithia,  Li20;  with  (5)  calcium,  lime,  CaO;  with  (6)  magne- 
sium, magnesia,  MgO ;  with  (7)  iron  (ferrum),  the  two  oxides,  FeO  and  Fe203; 
with  ($)  aluminium  (the  metallic  base  of  clay),  alumina,  A1203;  with  (9) 

61 


62  STRUCTURAL   GEOLOGY. 

carbon,  carbon  dioxide  (or  carbonic  acid),  C02;  with  (10)  silicon  (the  name 
from  the  Latin  silex,  flint),  silica,  Si02. 

These  and  other  essentially  stable  oxides  are  the  chief  constituents  of  rock- 
making  materials.  They  are  in  strong  contrast  with  the  compounds  that 
make  up  organic  tissues,  or  those  of  plants  and  minerals.  These  contain, 
along  with  the  oxygen  present,  carbon,  hydrogen,  nitrogen,  and  generally  a 
little  sulphur  and  phosphorus,  elements  that  have  a  strong  affinity  for 
oxygen,  but  they  are  associated  with  too  little  oxygen  to  satisfy  their  affini- 
ties, and,  moreover,  all  are  under  a  degree  of  restraint  from  the  living 
conditions.  When  these  conditions  are  removed  at  death,  ordinary  chemical 
affinities  rule,  and  oxides  are  formed  out  of  the  elements  of  the  tissues,  and 
of  outside  as  well  as  inside  oxygen  —  C02,  CO,  H20  being  the  chief  products. 
If  outside  oxygen  is  mainly  excluded  during  the  decomposition,  hydrocar- 
bon compounds  form,  or  those  that  constitute  mineral  coal,  oil,  gas,  and  the 
black  or  brown  carbonaceous  material  that  colors  soil  and  many  rocks ;  but 
these  on  burning  become  mostly  C02  and  H20. 

Carbon.  —  Carbon  is  a  prime  element  in  living  structures,  as  silicon  is  in 
rock-making  minerals.  In  its  pure  state,  crystallized  in  octahedrons  and 
related  forms,  it  is  the  diamond,  the  hardest  of  minerals.  Crystallized  in 
six-sided  tables  or  scales  of  a  dark  lead-gray  color,  it  is  graphite  (or  plum- 
bago), one  of  the  softest  of  minerals ;  often  called  "  black  lead,"  because  it 
leaves  a  trace  on  paper  much  like,  but  darker  than,  that  of  lead.  Substances 
having  like  composition,  but  different  in  crystallization,  as  diamond  and 
graphite,  are  called  paramorphs.  Charcoal  is  nearly  pure  carbon,  but 
contains  some  hydrogen  and  oxygen;  and  the  best  mineral  coal  is  only 
75  to  85  per  cent  carbon.  Carbon  combined  with  oxygen,  forming  C02,  or 
carbon  dioxide,  is  given  out  in  the  respiration  of  animals,  and  is  thus 
contributed  to  the  air,  and  by  aquatic  animals  to  the  waters,  and  is  a  large 
result,  as  before  explained,  of  all  decay.  At  the  same  time,  it  is  the  source 
of  carbon  to  the  growing  plant.  Carbon  dioxide  has  great  geological 
importance  through  its  combination  with  lime  (CaO),  producing  calcium 
carbonate,  the  formula  of  which  is  CaC03  (or  its  equivalent  CaO  +  C02), 
the  material  of  ordinary  limestone. 

Silicon.  —  Silicon  combined  with  oxygen,  and  thus  making  silica  (Si02), 
constitutes  the  two  minerals,  quartz  and  opal.  Quartz  is  the  most  abundant, 
durable,  and  indestructible  of  common  minerals.  Silica  also  enters  into 
combination  with  various  oxides,  and  thus  makes  silicates. 

Of  the  oxides  in  these  silicates,  alumina,  A1203,  is  the  hardest,  most 
infusible,  and  most  indestructible.  Like  silica,  it  is  well  fitted  for  a  chief 
place  in  the  earth's  foundations ;  and  next  to  silica  it  is  the  most  abundant. 

Silica  combined  with  alumina  alone,  makes  only  infusible  silicates  ;  but  if 
potash,  soda,  lime,  magnesia,  or  the  oxides  of  iron  are  present,  the  minerals 
in  general  are  fusible,  and  are,  therefore,  suited  for  the  material  of  a  melted 
as  well  as  of  a  solid  globe. 


HOCKS  I    THEIR    CONSTITUENTS   AND   KINDS.  63 

Sulphur.  —  The  element  sulphur  has  great  importance  in  the  mineral 
kingdom,  but  more  so  in  connection  with  the  ores  of  various  metals  than 
among  ordinary  rock  materials.  Sulphur  is  a  common  volcanic  product. 
Sulphur  dioxide,  or  sulphurous  acid  (S02),  is  abundant  in  the  vapors  of 
volcanoes;  and  sulphur  trioxide  with  water  (S03H20),  the  so-called  sul- 
phuric acid,  enters  into  combinations  with  other  oxides,  making  sulphates. 

Phosphorus.  —  Phosphorus  forms  an  acid  with  oxygen,  phosphorus  pent- 
oxide  (C205),  which  combines  with  calcium  and  oxygen  and  makes  calcium 
phosphate,  a  chief  constituent  of  bones,  of  guano,  and  of  the  mineral  apatite. 
There  are  also  phosphates  of  iron,  lead,  copper,  etc. 

Nitrogen.  —  Seventy-nine  per  cent  of  the  atmosphere  is  nitrogen,  the  rest 
being  oxygen.  Nitric  acid  (N205)  forms  nitrates;  common  saltpeter  is  a 
potassium  nitrate.  Nitrogen  is  an  essential  constituent  of  animal  tissues, 
and  of  fungoid  plants,  or  those  that  are  not  green  in  color,  as  the  mushroom ; 
and  it  is  present  also  in  the  seeds  and  some  other  parts  of  higher  plants. 

Chlorine,  Bromine,  Fluorine,  Boron.  —  Chlorine  combined  with  sodium, 
60'7  per  cent  to  29'3,  forms  common  salt,  of  which  the  ocean  is  the  great 
depository.  There  are  also  among  ores,  chlorides  of  silver,  lead,  and  copper. 
Bromides  occur  in  the  ocean's  water  and  in  some  minerals.  Fluorine  is  a 
constituent  of  the  common  mineral,  fluor  spar  or  fluorite  (CaF),  and  also 
exists  in  the  minerals,  topaz,  chondrodite,  and  a  few  others.  Boron  occurs  in 
boracic  acid,  in  borax,  which  is  a  sodium  borate,  and  in  the  mineral  silicates, 
tourmaline,  danburite,  and  datolite. 

THE  CHIEF  ROCK-MAKING  MINERALS. 

The  following  brief  descriptions  of  minerals  are  intended  as  notes  of  refer- 
ence. A  sufficient  knowledge  of  the  subject  for  the  geologist  can  be  obtained 
only  by  a  special  study  of  mineralogy. 

I.   Silica. 

QUARTZ.  —  Hardness  7  (not  scratched  with  the  point  of  a  knife-blade).  G=2-65. 
Infusible  and  insoluble,  but  fusible  to  glass  when  mixed  with  soda  and  heated  (quartz 
sand  and  soda  being  constituents  of  common  glass) .  No  cleavage.  Often  like  glass  in 
luster  and  transparency,  but  varying  to  dull  and  opaque,  and 
from  colorless  to  yellow,  red,  purple,  brown,  black,  etc.  Often 
in  crystals  like  Figs.  32, 1  33,  the  crystals,  six-sided  prisms 
with  pyramids  at  one  or  both  ends;  often  closely  covering 
the  surfaces  with  the  pyramids.  Composition  :  Silicon  46-67, 
oxygen  53-33  =  100.  Common  in  massive  forms,  either  glassy 
or  of  various  dull  colors,  and  of  little  luster.  The  stones  and 
sand-grains  of  the  fields  and  beaches  are  mostly  quartz.  This  is 
due  to  the  fact  that  nearly  all  other  kinds  of  common  stones  are  softer  and  get  worn  down 
to  earth  before  quartz.  Among  massive  varieties  :  flint  and  chert  are  dull-lustered,  with 
usually  a  smoky  or  blackish  color,  but  varying  to  yellowish,  brownish,  and  other  shades. 

1  In  the  figures  of  crystals  O  indicates  the  basal  plane ;  1,1,  the  prismatic  faces  of  the  funda- 
mental prism  ;  and  R,  a  face  of  the  fundamental  rhombohedron  in  rhombohedral  forms. 


64 


STRUCTURAL   GEOLOGY. 


OPAL. — Uncrystallized  silica,  a  little  less  hard  than  quartz  and  of  less  density 
(G=2-3),  and  having  usually  a  greasy  or  waxy  luster.  Colors,  white  to  milky  gray,  red, 
etc.  ;  when  showing  internal  colored  reflections  it  is  the  gem,  opal.  Opal  is  identical 
with  quartz  in  composition,  yet  commonly  contains  some  water  ;  it  dissolves  more  readily 
in  heated  alkaline  waters.  Here  belongs  the  material  deposited  by  the  hot  waters  of 
geysers,  making  the  geyser  basins  (sometimes  called  geyserite)  ;  also  the  siliceous 
secretions  of  Sponges,  and  the  shells  of  Radiolarians,  and  of  the  minute  microscopic  plants 
called  Diatoms. 

TRIDYMITE.  — Pure  silica  of  the  density  of  opal,  but  occurring  in  minute  thin  glassy 
hexagonal  crystals,  in  obsidian  and  some  other  volcanic  rocks. 

2.   Alumina. 

SAPPHIRE  OR  CORUNDUM. — Composition:  Al2O3=oxygen  46-8,  aluminium  53-2  =  100. 
The  crystals  are  the  hardest  of  gems  next  to  the  diamond  ;  the  blue  transparent  crystals 
are  sapphire,  the  red  crystals,  oriental  ruby ;  and  the  coarser  material  when  ground 
makes  emery. 

3.   Silicates  of  Aluminium  and  oilier  Basic  Elements. 

THE  FELDSPARS.  —  The  feldspars  are  next  in  abundance  to  quartz.  Luster  nearly 
like  quartz,  but  often  somewhat  pearly  on  smooth  faces.  H=6|-7,  or  very  nearly  as  hard 
as  quartz.  Specific  gravity  2-4-2-6.  In  general  white  or  flesh-colored  ;  rarely  greenish  or 
brownish.  Crystals  stout,  never  acicular.  Differs  from  quartz  in  having  a  perfect  cleav- 
age in  one  direction,  yielding  under  the  hammer  a  smooth  lustrous  surface,  and  in  another, 
nearly  as  perfect  a  cleavage  surface,  the  two  inclined  84°  to  90°  to  one  another ;  also  in  being 
more  or  less  fusible  before  the  blow-pipe.  Composition :  Silica  and  alumina  with  either 
potash,  soda,  or  lime,  or  two  or  all  of  these  combined.  Contains,  unless  impure,  no  iron 
or  magnesia. 

The  group  of  feldspars  includes  several  species  differing  in  the  proportion  of  silica 
(the  acid)  to  the  other  ingredients  (bases),  and  in  the 
particular  alkali  (potash,  soda,  or  lime)  predominant, 
but  they  graduate  to  some  extent  into  one  another.  The 
kinds  are  as  follows  :  — 

Orthoclase,  or  potash-feldspar,  is  the  most  common. 
The  cleavage   surfaces   make   a  right  angle   with    one 
another,  whence  the  name,  signifying  cleaving  at  a  right 
angle  ;  the  form  is  monoclinic.     Figs.  34,  35,  36,  repre- 
sent crystals  of  this  species,  the  last  a  twin  crystal ;  cleavage  takes  place  parallel  to  the 
faces  0  and  ii.     Composition  :  Silica  64-7,  alumina  18-4,  potash  16-9=100. 

The  other  kinds  are  triclinic  in  crystallization,  and  the  cleavages  make  an  oblique 
angle  with  one  another,  of  84° -89°  44',  and  hence  they  are  sometimes  called  plagioclase, 
from  the  Greek  plagios,  oblique. 

Microdine.  —  Like  orthoclase  in  composition  ;  but  the  cleavage  angle  differs  16'  from 
90°.  The  chief  distinctions  are  optical. 

Albite.  —  A  soda  feldspar,  named  from  the  Latin  albus,  white.  When  albite  and 
orthoclase  occur  together,  albite  is  usually  the  whiter.  Composition  :  Silica  68-6,  alumina 
19-6,  soda  11-8  =  100.  A  little  more  fusible  than  orthoclase. 

Oligoclase.  —A  soda-lime  feldspar.  Composition :  Silica  61-9,  alumina  24-1,  lime  5-2, 
soda  8-8=100.  Fuses  like  albite. 

Labradorite.  —  A  lime-soda  feldspar.  Composition :  Silica  52-9,  alumina  30-3,  lime 
12-3,  soda  4-5  =  100.  Fuses  easily,  named  from  Labrador.  Andesite  is  a  species  between 
oligoclase  and  labradorite  in  composition,  named  from  the  Andes. 

Anorthite.  —  A  lime  feldspar.    Composition :  Silica  43-1,  alumina  36-8,  lime  20-1  =  100. 


KOCKS  :    THEItt    CONSTITUENTS   AND   KINDS. 


65 


Fuses  with  much  difficulty.    The  first  four  of  the  above  species  contain  over  60  per  cent  of 

silica,  and  hence  are  called  acidic  feldspars,  while  labradorite  and  anorthite  are  called 

basic  feldspars. 

The  following  are  a  few  other  related  silicates  containing  potash,  soda,  or  lime  :  — 
LEUCITE.  — In  white  to  gray  trapezohedrons,  like  those  of  garnet  (Fig.  44,  page  66). 

Occurs  in  some  lavas,  as  those  of  Vesuvius.    Composition  :  Silica  55-0,  alumina  23 '5,  potash 

21-5=100.     Infusible. 

NEPHELITE.  — In  hexagonal  prisms  and  massive  ;  luster  of  the  massive,  greasy,  hence 

the  name  elceolite  from  the  Greek  elaion,  oil.     Composition:  Silica  44-0,  alumina  33-2, 

soda  15-1,  potash  7-7  =  100.     Fuses  easily.     Treated  with  hot  hydrochloric  acid  forms  a 


37. 


Scapolite. 
Often  used, 


jelly. 

SCAPOLITES. — In  square  prisms  with  square  pyramidal  terminations. 
Fuses  easily.  Several  species  are  here  included.  Wernerite  has  the  com- 
position :  Silica  48-4,  alumina  28-5,  lime  18-1,  soda  5'0=:  100.  Meionite  is 
a  lime-scapolite. 

SAUSSURITE. — A  compact  whitish  uncrystalline  mineral  into  which 
crystals  of  labradorite  and  anorthite  are  sometimes  changed.  Contains 
soda  and  has  nearly  the  composition  of  labradorite.  Has  a  higher  specific 
gravity  than  the  feldspars,  2-9-3-5. 

THE  MICA  GROUP.  —  The  micas  are  cleavable  into  thin  elastic  leaves, 
when  transparent,  in  the  doors  of  stoves  and  lanterns.  Occurs  colorless  to  brown,  green, 
reddish,  and  black  ;  and  either  in  small  scales  disseminated  through  rocks  —  as  in  granite 
—  or  in  plates  a  yard  in  diameter.  Contains  silica,  alumina,  and  much  potash  or  soda, 
like  a  feldspar,  but  besides  these,  in  most  species,  magnesia  and  iron,  which  do  not  exist 
in  any  feldspars.  Fluorine  is  sometimes  present.  Some  varieties  resemble  crystallized  talc 
and  chlorite,  from  which  they  differ  in  being  elastic.  But  hydrous  micas  are  generally  in- 
elastic, and  have  also  the  greasy  feel  of  talc.  The  more  common  species  of  mica  are  :  — 

Muscovite  (Muscovy  glass  of  early  mineralogy). — Light  colored  to  brownish,  and 
usually  transparent  in  thin  leaves.  One  variety  afforded  silica  46-3,  alumina  36-8,  iron 
sesquioxide  4-5,  potash  9-2,  fluorine  0-7,  water  1-8  =  99-3.  Three  to  five  per  cent  of 
water  are  often  present ;  and  when  4  to  5  per  cent,  it  is  called  hydromica  (or  hydrous 
mica).  Sericite  and  damourite  are  kinds  of  hydromica. 

Biotite.  —  Color,  usually  black,  rarely  white.  One  analysis  afforded  silica  40.0, 
alumina  17-28,  iron  sesquioxide  0-72,  iron  protoxide  4-88,  magnesia  23*91,  potash  8-57, 
soda  1-47,  water  1-37,  fluorine  1-57  =  99-77.  Another  black  mica,  lepidomelane,  contains 
20  to  30  per  cent  of  iron  oxides. 

Phlogopite.  —  A  brown  mica  occurring  in  crystalline  limestone  in  northern  New  York. 

The  following  are  other  aluminium  silicates  often  disseminated  through  crystalline 
schists  or  slates :  — 


Andalusite,  var.  Chiastolite. 


Staurolite. 


ANDALUSITE,  CYANITE  (spelt  also  Kyanite),  FIBROLITE,  are  alike  in  composition,  con 
sisting  simply  of  silica  36-9  and  alumina  63-1  =  100.     They  occur  in  oblong  prisms,  often 
DANA'S  MANUAL  —  5 


STRUCTURAL  GEOLOGY. 


slender.  Have  H  =  6-7.  Are  infusible.  Andalusite  occurs  in  gray,  stoutish,  nearly 
square,  prisms  (90°  48')  which  are  often  tesselated  inside  with  white  (then  called  chias- 
tolite).  Cyanite  is  commonly  in  long,  bluish,  bladed  crystals ;  and  fibrolite  in  rhombic 
prisms  and  fibers,  having  a  brilliant  diagonal  cleavage. 

STAUROLITE.  — In  rhombic  prisms  of  129°  20',  imbedded  in  slaty  rocks.  Usual  colors, 
brown  to  black.  The  crystals  are  often  crossed  as  in  Fig.  39,  and  hence  the  name,  from 
the  Greek  for  cross.  H  =  7-7 J.  Composition:  Silica  29-3,  alumina  53-5,  sesquioxide  of 
iron  17-2  =  100.  Infusible. 

TOURMALINE. — Usually  in  three-sided  or  six-sided  black  crystals,  having  the  luster 
within,  when  black,  like  that  of  a  black  resin  ;  and  it  has  no  distinct  cleavage,  and  thus 
differs  from  hornblende.  Figs.  40,  41  show  two  of  the  forms ;  and  Fig.  42,  the  appear- 


40. 


41. 


Tourmaline. 


Tourmaline. 


ance  of  the  crystals  in  the  rock,  which  is  often  quartz.  Besides  black,  there  are  also  brown, 
green,  red,  and  white  tourmalines.  H  =  7-7£.  Constituents  :  Silica,  alumina,  magnesia, 
with  fluorine  and  some  boracic  acid.  Fusible,  but  fusibility  varying  much  in  varieties. 

GARNET.  —  In  crystals  of  the  forms  in  Figs.  43,  44.  H  =  6i-7£.  Colors  usually  red 
to  brown  and  black,  rarely  green  and  colorless ;  sometimes  chrome-green.  H  =  6-7. 
Consists  of  silica  and  alumina,  with  either  iron,  or  lime,  or  manganese,  and  varying  in  its 
characters  according  to  composition. 


EPIDOTE.  —  In  yellowish  green  to  hair-brown  prismatic  crystals  and  masses.  A  peculiar 
yellowish  green  color  is  most  common.  It  has  nearly  the  composition  of  an  iron  garnet. 
G  =  3-25-3-5.  Zoisite  is  a  related  mineral  of  ash-gray  to  whitish  color,  containing  much 
Ihne  and  little  or  no  iron.  It  has  high  specific  gravity,  G  =  3-1-3-4.  Constituents  as  in 
garnet. 

IDOCRASE.  —  In  square  prisms,  of  a  brown  to  oil-green  color. 
H  =  61.  Composition  :  One  kind,  silica  37-3,  alumina  16-1,  iron 
sesquioxide  3-7,  lime  35-4,  magnesia  2-1,  iron  protoxide  2-9, 
water  2-1  =  99-6.  Fusible. 

TOPAZ. — In  rhombic  prisms  of  124°  17',   remarkable  for 
cleaving  with  ease  and  brilliancy  parallel  to  the  base  of  the 
Topaz.  prism.     Colors,  yellowish  to  white,  also  brown.     Two  of  the 

forms  of  its  crystals  are  shown  in  Figs.  45,  46.  H  =  8.  Con- 
sists of  silica  16-2,  silicon  fluoride  28-1,  alumina  55-7  =  100.  The  amount  of  fluorine 
present  is  a  remarkable  quality.  Infusible. 


ROCKS  :    THEIR   CONSTITUENTS   AND   KINDS. 


67 


ZIRCON,  BERYL,  TITANITE  (Sphene)  are  other  anhydrous  silicates.  Zircon  is  a  silicate 
of  zirconia;  beryl  (aquamarine  when  pale  green  and  transparent),  a  silicate  of  alumina 
and  beryllia  ;  titanite  or  sphene,  a  silicate  of  calcium  and  titanium. 

4.  Silicates  of  Magnesium  and  Iron  or  Calcium,  with  Little  or  no  Alumina  and 

no  Water. 

CHRYSOLITE.  —  Occurs  in  green  glassy  grains  or  crystals  in  basalt  and  related  rocks, 
and  also  paler  green  in  rock  masses.  Also  called  olivine,  and  in  France  peridot.  H  =  6-7. 
Infusible.  Composition  of  a  common  variety  :  Silica  41-4,  magnesia  50-9,  iron  protoxide 
7*7  =  100.  A  related  mineral,  fayalite,  contains  iron  without  magnesium,  and  is  fusible. 
The  crystals  often  occur  changed,  partly  or  wholly,  to  serpentine. 

CHONDRODITE.  — A  yellow  to  brown  magnesium  silicate,  containing  fluorine,  occurring 
in  crystalline  limestones.  A  kind  found  in  ejected  masses  of  limestone  at  Vesuvius 
is  called  humite. 

HORNBLENDE  (often  called  amphibole). — Occurs  in  prisms  of  124°  30'  (which  is 
also  the  cleavage  angle).  Colors  various,  from  black  to  green  and  white.  The  most 
common  kind  in  rocks  is  an  iron-bearing  variety,  in  black  cleavable  grains  or  in  oblong 
black  prisms.  Figs.  47,  48,  and  49  represent  common  crystals,  and  50  tufts  of  crystals 
as  they  often  appear  in  some  rocks.  The  kind  in  slender  green  crystals  or  fibers  is 
called  actinolite  —  a  common  form  of  its  crystals  is  shown  in  Fig.  49 ;  the  white  (a  kind 
common  in  crystalline  limestones,  and  containing  much  lime),  tremolite.  The  mineral 


49. 


is  common  in  fibrous  masses  ;  and,  when  the  fibers  are  as  fine  as  flax,  it  is  called  asbestos. 

A  common  black  hornblende  consists  of  silica  48-8,  alumina  7*5,  magnesia  13-6,  lime 

10-2,  iron  protoxide  18-8,  manganese  protoxide,  1-1  =  100. 

PYROXENE   (including  augite). — Like  hornblende  in  chemical  composition  and  in 

most  of  its  characters ;  but  the  crystals,  as  in  the  annexed  figures,  51,  52,  instead  of 
being  prisms  of  124°  30',  are  prisms  of  87°  5'  or  nearly  (angle  / 
on  /),  and  are  often  eight-sided  from  the  truncation  of  the  four 
edges,  as  in  Fig.  52.  Pyroxene  and  hornblende  are  hence  para- 
morphs,  being  different  in  crystallization,  but  alike  in  composition. 
Black  and  dark  green  pyroxene  in  short  crystals  is  called  augite  ; 
it  is  an  iron-bearing  kind,  and  is  common  in  igneous  rocks. 

ENSTATITE. — Near  pyroxene   in   cleavage   angle,  but  prisms 
orthorhombic.     Infusible   or  nearly  so.     It  is  in  part  a  silicate 

of  magnesium.     When  a  silicate  of  magnesium  and  iron,  it  is  often  called  bronzite  ;  and, 

if  containing  much  iron,  hypersthene. 

5.    Silicates  of  Magnesium,  etc.,  with  Water. 

TALC.  —  Very  soft,  H=l.  Crystallizes  in  flexible  folia  like  mica,  but  inelastic;  also 
massive-granular  (soapstone  or  steatite);  white  and  very  fine-grained  (French  chalk). 
Feels  very  greasy.  Consists  of  silica  62-3,  magnesia  33-5,  water  3-7  =  100.  Infusible. 


68 


STRUCTURAL   GEOLOGY. 


SERPENTINE.  —  Oil-green  to  blackish  and  yellowish  green  to  greenish  white  ;  massive 
or  fibrous ;  often  having  the  crystalline  form  of  another  mineral.  H=3 ;  feels  somewhat 
greasy.  Consists  of  silica  4348,  magnesia  43-48,  water  13-04  =  100.  Mixed  with  lime- 
stone it  is  verd-antique  marble. 

THE  CHLORITE  GROUP. — Like  green  mica  when  crystallized,  but  inelastic;  usually 
granular-massive  ;  of  a  dark  green  color,  and  greasy  feel.  Silica  from  25  to  35  per  cent 
in  the  different  species;  the  other  ingredients  are  alumina,  magnesia,  iron,  etc.,  with 
12  to  14  per  cent  of  water. 

6.    Silicates  of  Alumina  Containing   Water. 

KAOLINITE.  —  Pure  white  clay,  derived  usually  from  the  decomposition  of  orthoclase 
—  the  silica,  alumina,  and  potash  of  the  orthoclase  changing  to  a  compound  of  silica, 
alumina,  and  water,  by  the  loss  of  potash  and  gain  of  water  in  its  place.  Consists  of  silica 
46-4,  alumina  39-7,  water  13-9  =  100. 

Besides  the  hydrous  micas,  there  are  the  common  species  :  — 

FINITE  OR  AGALMATOLITE.  — A  compact  mineral,  soapy  to  the  touch,  often  resembling 
a  compact  soapstone.  Like  serpentine  and  massive  pyrophyllite,  it  is  often  cut  into 
images  in  China.  Consists  of  silica,  alumina,  potash,  and  water. 

PYROPHYLLITE. — A  mineral  resembling  talc  in  color,  cleavage,  and  soapy  feel  when 
crystallized,  and  like  some  fine-grained  soapstone  when  massive.  Consists  of  silica, 
alumina,  and  water.  It  differs  from  talc  in  containing  alumina  in  place  of  magnesia. 

GLAUCONITE  OR  GREEN  EARTH.  —  The  material  of  the  New  Jersey  marl,  or  Green  sand 
of  the  Cretaceous  and  other  rocks.  It  is  a  soft,  dark  or  light  green  silicate  of  alumina, 
iron,  and  potash,  with  water. 

ZEOLITES.  —  Stilbite,  chabazite,  analcite,  natrolite,  prehnite,  are  some  of  the  zeolites 
(a  word  derived  from  the  Greek  for  to  boil,  the  species  fusing  easily  with  intumescence). 
They  are  hydrous  species,  consisting  of  silica,  alumina,  lime  or  soda,  and  water. 
Laumontite  is  another  related  hydrous  silicate.  They  are  common  minerals  in  the 
cavities  of  amygdaloid  and  some  other  rocks.  Pectolite  is  a  hydrous  silicate  of  lime, 
found  in  fibrous  forms,  under  similar  circumstances. 

7.    Carbonates. 

CALCITE  (or  calcium  carbonate),  often  called  carbonate  of  lime.  It  is  the  material  of 
common  limestones.  H  =  3,  it  being  easily  scratched  ;  and  G  =  2-715,  when  pure.  Com- 
position :  Ca03C  =  Carbonic  acid  44-0,  lime  56-0  =  100.  When  dropped  in  powder  into 

hydrochloric  acid  diluted  with  one  half  water,  it  ef- 
fervesces strongly,  giving  off  carbonic  acid.  The 
annexed  are  some  of  the  forms  it  presents  when 
crystallized.  It  cleaves  alike  in  three  directions, 
making  the  angle  105°  5'  with  one  another  ( =  R  on 
E  in  Fig.  53  A);  the  form,  Fig.  53  A,  is  called  a 
rhombohedron.  When  crystallized,  calcite  is  often 
transparent  and  colorless.  But  the  mineral  occurs  of 
various  colors  from  white  to  black,  and  the  massive 
kinds  from  translucent  to  opaque.  All  the  common 
marbles  are  limestones,  either  of  this  mineral  species 
or  the  following,  or  mixtures  of  the  two. 

Dolomite  (or  calcium-magnesium  carbonate). — 
Resembles  calcite  so  closely  that  the  two  cannot  often 

be  distinguished  except  by  chemical  means.  It  constitutes  many  limestone  strata,  both 
massive  and  crystalline.  When  dropped  in  powder  into  cold  dilute  muriatic  acid,  it 
effervesces  very  feebly  ;  but  on  heating,  a  brisk  effervescence  is  produced.  Cleavage  angle 


53. 


ROCKS:    THEIR   CONSTITUENTS   AND   KINDS.  69 

106°  15',  and  this,  with  crystallized  specimens,  is  an  important  means  of  distinction. 
Composition:  Carbonate  of  lime  54-4,  carbonate  of  magnesia  45-6  =  100.  Formula, 
(iCa|Mg)03C. 

SIDERITE  (iron  carbonate).  —  A  valuable  ore  of  iron,  sometimes  called  steel  ore.  Crys- 
tallizes and  cleaves  like  the  preceding,  but  much  heavier.  G  =  3-7-3-9.  Color  white  to 
gray,  but  becoming  brown  on  exposure  to  the  air  because  the  iron  oxidizes  easily  and 
changes  to  limonite.  Cleavage  angle  107°.  Occurs  also  massive,  gray  to  brown,  with 
feeble  luster.  Formula,  FeO3C  (=  FeO  +  C02). 

ARAGONITE.  — Like  calcite  in  composition,  but  occurring  in  prismatic  form,  without  the 
cleavages  of  calcite.  Calcite  and  aragonite  are  hence  paramorphs.  G  =  2-9-2-94,  which 
is  above  that  of  calcite.  Shells,  while  consisting  generally  of  calcium  carbonate,  often 
have  a  large  part  of  the  material  in  the  aragonite  state ;  and  hence  aragonite  is  present 
through  most  uncrystalline  limestones. 

8.    /Sulphates. 

GYPSUM  (or  hydrous  calcium  sulphate).  —  Very  soft.  H  =  1.  One  of  the  few  minerals 
that  may  be  easily  impressed  with  the  teeth  without  producing  a  grating  sensation.  Often 
massive  and  fine  granular.  Colors  from  white  to  black  ;  the  white  is  common  alabaster. 

Also  occurs  in  crystals,  with  pearly  luster  on  a  cleav- 

54.  55.  age  surface.    Figs.  54,  55  give  two  of  the  forms  of 

the  crystals.  It  cleaves  in  broad  pearly  plates  or  folia, 
which  look  like  mica,  but  are  softer,  and  not  elastic. 
Unlike  limestone  and  other  minerals,  a  little  heat 
reduces  it  to  powder,  making  the  common  plaster  of 

Paris  of  the  shops.  It  consists  of  sulphuric  acid  46-51,  lime  32-56,  water  20-93  =  100. 
Formula,  CaO4S  +  2  aq  (=  CaO.  S03  2  aq). 

ANHYDRITE  (calcium  sulphate,  without  water).  —  White  and  gray- 
ish, reddish.  H  =  3-3 \.  Cleavage  affords  rectangular  blocks  or  plates. 
It  differs  from  gypsum  also  in  affording  no  water  when  heated. 

BARITE  (or  heavy  spar,  barium  sulphate,  also  called  barytes). 
—  Occurs  in  tabular  crystals,  some  of  the  forms  of  which  are 
given  in  Fig.  56.  It  is  remarkable  for  its  high  specific  gravity 
(G  =  4-3-4-7),  whence  the  name,  from  the  Greek  for  weight.  It 
contains  sulphuric  acid  34-3,  baryta  65-7  =  100.  Formula,  BaO4S 
(=  BaO  +  SO3).  It  is  ground  up  and  used  for  adulterating  white 
lead  paint.  It  is  common  as  a  gangue  of  different  ores. 

9.   Phosphates,  Fluorides. 

APATITE  (calcium  phosphate). — Occurs  in  six-sided  prisms  of  a  greenish  to  bluish 
color,  often  looking  like  beryl  (and  this  deceptive  appearance  led  to  the  name  from  the 
Greek,  signifying  to  deceive"),  but  easily  distinguished  from  beryl  by  its  inferior  hardness, 
as  it  maybe  scratched  with  a  knife.  Composition:  Phosphoric  acid  40-92,  lime  53-80, 
chlorine  6-82  =  101-54,  for  a  chlorine-bearing  variety.  Another  kind  contains  fluorine 
instead  of  chlorine.  Much  used  for  making  a  fertilizer. 

FI.UORITE  (fluor  spar,  calcium  fluoride). — Crystallizes  in  cubes,  octahedrons,  and 
other  related  forms,  which  cleave  easily  in  four  directions,  parallel  to  the  faces  of  the 
regular  octahedron,  the  faces  of  cleavage  making  angles  with  one  another  of  109°  28'. 
Often  granular-massive.  Easily  scratched  with  a  file.  Colors,  clear  purple,  yellow,  blue, 
often  white,  and  of  other  shades.  Massive  varieties  are  worked  into  vases,  etc.,  which 
have  much  beauty.  When  powdered  and  thrown  on  a  shovel  heated  nearly  to  redness,  it 
phosphoresces  brightly.  Composition :  Fluorine  48-7,  calcium  51-3  =  100. 


70  STRUCTURAL   GEOLOGY. 

10.     Sulphides,  or  Minerals  Containing  Sulphur. 

PYRITE.  —  Color  pale  yellow,  brass-like,  much  less  yellow  than  chalcopyrite.     Hard- 
ness 7,  or  sufficient  to  strike  fire  with  steel,  whence  the  name,  from  the   Greek  for 
fire.     Occurs  often  in  cubes  like  Fig.  57.     The  striae  of  the  adjoining  surfaces,  when  any 
are  present,  are  at  right  angles  with  one  another.     Also  in  other  related 
forms.     Frequently  very  brilliant,  but  also  dull,  and  sometimes  brown 
from  a  coating  of  limonite.     Composition :  Sulphur  53-3,  iron  46-7  =  100  ; 
formula,  FeS2.   Common  in  all  rocks,  in  small  disseminated  crystals ;  often 
in  veins,  and  as  the  gangue  of  other  ores.     It  is  the  "gay  deceiver"  of 
the  mineral  world,  being  often  mistaken  for  silver  ores  (which  are  never 
yellow)  and  for  gold  (which  is  never  brittle  or  hard),  or  for  chalcopyrite 
or  copper  pyrites  (which  is  easily  scratched,  and  has   an   olive-green 
powder).     Often  contains  gold  invisibly  disseminated,  and  is  worked  for  its  gold;   not 
good  for  making  iron,  but  by  oxidation  converted  into  vitriol  (iron  sulphate),  and  used 
for  this  purpose  and  for  making  sulphuric  acid. 

MARCASITE.  —  Like  pyrite  in  composition  (FeS2)  and  hardness,  but  color  paler  and 
crystals  prismatic.  Pyrite  and  marcasite  are  paramorphs. 

PYRRHOTITE. — Iron  sulphide,  containing  sulphur  39-5,  iron  60-5  =  100;  formula, 
Fe7S8,  the  atomic  ratio  being  nearly  1  to  1.  Differs  from  pyrite  in  having  a  bronze-yellow 
color,  in  being  easily  scratched  (H  =  3}  to  4£),  and  in  crystallization.  Used  for  the  same 
purposes  as  pyrite.  Often  contains  nickel,  and  is  then  worked  for  this  metal. 

ARSENOPYRITE. — Silver-white,  brittle,  H  =  5-5-6,  much  above  that  of  silver  ores. 
Contains,  with  iron,  arsenic  as  well  as  sulphur ;  formula,  FeAsS.  Valuable  for  its  arsenic, 
and  sometimes  contains  cobalt  and  gold. 

CHALCOPYRITE  (copper  pyrites).  — Gold-yellow,  brittle  (in  this  unlike  gold)  ;  powder 
olive-green.  A  valuable  ore  of  copper,  consisting  of  sulphur  34-9,  copper  34-6,  iron 
30-5  =  100. 

GALENA. — Lead  sulphide,  of  light  steel-gray  color,  brittle.  Usually  breaks  into 
cubes  under  the  hammer,  unless  fine  granular-massive;  H  =  2-5.  The  common  ore  of 
lead.  Contains  sulphur  13-4,  lead  86-6  =  100  ;  formula,  PbS. 

SPHALERITE  (Blende). — Zinc  sulphide.  Luster  not  metallic,  but  resinous,  and  the 
powder  nearly  white.  Colors  yellow  and  brown,  looking  much  like  resin,  also  black, 
rarely  white.  Composition :  Sulphur  33,  zinc  67  =  100  ;  formula,  ZnS.  A  common  and 
valuable  ore  of  zinc. 

11.    Oxides. 

HEMATITE.— Oftsn  called  specular  iron  ore,  because  the  crystals  are  brilliant;  a 
steel-gray  ore  of  iron,  but  also  of  a  deep  red  color  when  earthy.  Consists  of  oxygen  30, 
iron  70  =  100  ;  formula,  Fe203.  Crystals  rhombohedral.  Powder  red,  and  hence  the 
name  (given  by  the  Greeks),  from  the  Greek  for  blood.  H  of  crystals  6.  The  red  ore 
is  red  ocher  (common  red  paint  and  red  chalk),  and  a  hard,  massive,  impure  kind  is  a 
variety  of  clay-ironstone.  A  valuable  but  hard  iron  ore,  Menaccanite  (Ilmenite,  or 
titanic  iron)  is  a  related  ore  containing  much  titanium  and  having  a  black  powder. 

MAGNETITE.  — Called  magnetic  iron,  because  easily  taken  up  with  a  magnet,  unlike 
other  iron  ores.  Color  blackish  iron-gray,  looking  much  like  hematite,  from  which  it 
differs  in  its  black  powder,  and  in  crystallizing  in  octahedrons  and  related  forms  ;  H  =  6. 
Composition  :  Oxygen  27-6,  iron  72-4=100  ;  formula,  Fe3O4.  Occurs  in  great  beds  like  the 
last,  and  also  common  in  disseminated  crystals ;  often  a  black  iron  sand  on  sea-beaches. 
A  valuable  ore  of  iron.  Franklinite  is  a  similar  ore  (from  Sussex  Co.,  N.J.),  containing 
nearly  7  per  cent  of  zinc  oxide  with  nearly  10  of  manganese  protoxide  ;  valuable  for  its 
zinc,  as  well  as  its  iron. 


BOCKS:     THEIR   CONSTITUENTS    AND    KINDS.  71 

LIMONITE.  —  A  brown,  brownish  black  to  ochre-yellow  iron  ore,  consisting  of  iron  in 
the  same  state  of  oxidation  as  hematite,  but  combined  with  water:  it  is  hence  equivalent 
to  hematite  plus  water,  Fe2O3  +  l-^HjO  =  iron  sesquioxide  85-6,  water  14-4  =  100.  Con- 
tains when  pure  59-9  per  cent  of  iron.  Its  powder  is  brownish  yellow  —  a  distinguishing 
character.  The  earthy  yellow  variety  is  the  common  paint,  yellow  ocher.  In  the  larger 
deposits  this  ore  is  a  secondary  product ;  that  is,  was  made  from  the  oxidation  of  iron- 
bearing  minerals  in  the  rocks  about  the  deposits.  So  named  from  the  Greek  for  marsh, 
because  a  common  ore  in  marshes,  marshes  being  the  earth's  smaller  pockets,  catching 
what  iron  is  decomposed  out  of  the  rocks  of  the  surrounding  hills  and  washed  in  by  the 
waters.  The  marsh  ore  is  often  contaminated  with  phosphates  from  organic  deposition, 
and  therefore  the  iron  it  yields  is  usually  fit  only  for  castings.  The  larger  deposits, 
not  of  marsh  origin,  are  commonly  pure,  or  nearly  so,  from  phosphates  and  sulphur ;  but 
they  may  contain  sulphur  when  the  ore  has  been  made  from  pyrite.  When  free  from 
sulphur  it  is  a  very  valuable  ore,  easily  worked.  Great  beds  occur  in  Salisbury,  Conn., 
Berkshire  County.,  Mass. ,  Amenia  and  elsewhere  in  eastern  New  York,  in  eastern  Penn- 
sylvania, and  farther  southwest,  and  in  many  other  states. 

MANGANITE,  PSILOMELANE,  PELAGITE.  —  Both  hydrous  and  anhydrous  oxides  of 
manganese  exist.  Manganite  is  a  hydrous  sesquioxide,  like  limonite  (under  iron)  ;  and 
psilomelane  is  a  massive,  impure  ore  of  related  character.  The  color  is  iron-black  and  the 
powder  black.  Over  the  sea-bottom  concretions  of  impure  hydrous  manganese  oxide 
occur,  which  have  been  named  pelagite.  An  analysis  gave  40  per  cent  of  this  oxide  to  27 
of  iron  sesquioxide,  with  13  per  cent  of  water,  14  of  silica,  and  40  of  alumina.  The 
manganese  is  supposed  to  come  from  the  pyroxene  of  volcanic  ashes. 

WATER. —Water  is  hydrogen  oxide,  H2O  =  Oxygen  88-89,  hydrogen  11-11  =  100. 
But  it  is  never  pure,  because  of  its  solvent  powers.  See  beyond,  page  118. 

ORGANIC  CONTRIBUTIONS  TO  THE  MATERIAL  OF  ROCKS. 

The  materials  of  most  rocks  are  of  mineral  origin.  The  rocks  have  been 
produced  by  fusion,  or  out  of  the  gravel,  sand,  or  clay,  made  through  the 
wear  and  decay  of  preexisting  rocks ;  and  as  the  constituents  drawn  upon 
were  mineral,  the  rocks  thus  derived  are  of  mineral  origin.  These  are  the 
most  common  of  rocks. 

But  besides  the  material  from  a  mineral  source,  large  contributions 
toward  rock-making  have  come  from  the  organic  kingdoms,  especially  from 
those  divisions  of  it  that  produce  hard,  stony  secretions.  Shells  and  corals 
are  examples  of  these  secretions.  Animals  secreted  them  for  protection,  sup- 
port, or  some  other  purpose ;  but  they  were  good  material  for  rock-making, 
and  through  the  geological  ages,  when  the  death  of  animals  has  set  them 
free,  they  have  been  converted  into  limestones.  Plants  are  the  source  of 
coal-beds.  Their  stems,  leaves,  tissues,  have  become  gathered  in  favorable 
places  into  beds,  like  a  peat-bed,  and  after  long  burial  have  been  converted 
into  coal.  Further,  some  kinds  of  animal  and  vegetable  life  secrete  silica, 
material  for  siliceous  accumulations. 

Organic  materials  may  occur  not  only  in  deposits  that  are  purely  of 
organic  origin,  but  also  mixed  with  material  of  mineral  origin,  that  is,  with 
sand,  clay,  gravel,  and  the  like,  in  various  proportions ;  and  sometimes  a  few 
organic  relics  are  all  the  materials  of  an  organic  source  that  can  be  distin- 
guished. The  organic  relics  preserved  in  any  rock  are  called  fossils  (from 


72  STRUCTURAL  GEOLOGY. 

the  Latin  for  dug  up),  and  a  bed  of  rock  containing  fossils  is  described  as 
fossiliferous. 

The  following  are  the  chief  sources  of  materials  of  organic  origin :  — 
Calcareous,  or  the  material  of  limestones.  —  The  most  important  animal 
sources  are  shells  of  Mollusks,  Corals,  Crinoids,  Foraminifers  or  the  shells 
of  ordinary  Rhizopods.  The  sources  under  the  vegetable  kingdom  are  Coral- 
lines of  calcareous  or  semi-calcareous  nature,  Confervoid  and  other  Algse, 
some  of  which,  as  the  Nullipores,  have  coral-like  forms,  while  others  are 
minute  and  disk-shaped,  as  the  Coccospheres  or  Coccoliths. 

The  following  are  analyses :  1  and  2,  Corals,  Madrepora  palmata  and  Oculina  arbus- 
cula,  by  S.  P.  Sharpies ;  3,  shell  of  a  Terebratula,  by  the  same  ;  4,  shell  of  an  oyster  :  — 

1.  2.  3.  4. 

Madrepora.  Oculina.  Terebratula.    Oyster-shell. 

Calcium  carbonate 97-17  95-37  98-39  93-9 

Calcium  phosphate 0-78  0-84  0-61  0-5 

Calcium  sulphate —  0-4 

Magnesium  carbonate —  0'3 

Water  and  organic  matters 2-81  3-79  1-00  3-9 

In  a  Millepore  (?)  Coral  Damour  found  8.51  per  cent  of  magnesium  carbonate  in  one 
species,  and  little  in  others.  Forchhammer  obtained  6-36  per  cent  of  magnesium  carbonate 
from  the  Coral,  Isis  nobilis,  and  2-1  per  cent  in  the  precious  Coral  of  the  Mediterranean, 
Corallium  nobile.  Of  the  Charce,  among  plants,  Ch.fcetida  affords  31-33  per  cent  of  ash, 
95-35  per  cent  of  which  is  calcium  carbonate. 

Siliceous.  —  The  animals  that  secrete  silica  are,  in  the  main,  (1)  the 
Sponges,  and  (2)  the  Kadiolarians,  a  radiate  section  of  the  Ehizopods ;  and 
the  vegetables  are  chiefly  the  minute  Diatoms  and  other  algoid  species. 

Sponges  usually  consist  largely  of  fine  horny  fibers.  Those  used  for 
household  purposes  are  an  exception,  and  are  selected  for  this  use  because 
free  from  such  fibers,  and  therefore  pliant  and  strong.  The  silica,  when 
present,  is  in  spicules,  bristling  with  horny  fibers,  easily  detected  with  a  good 
pocket  lens.  In  some  species  they  are  so  abundant  as  to  make  a  net-work  of 
silica,  as  in  the  pure  "  glass-sponge,"  free  from  all  horny  fiber.  See  page  57 
for  a  figure  of  one  of  the  species. 

Phosphatic.  —  The  chief  sources  among  animal  materials  are  bones,  teeth, 
epidermis,  and  other  tissues,  excrements,  and  the  shells  of  Lingulcc,  Discince, 
Obolus,  Pteropods,  etc. ;  the  outer  integuments  or  shell  of  Crustaceans, 
Insects,  etc. ;  and  those  of  a  vegetable  source  are  the  stems,  leaves,  and  fruit 
of  plants,  especially  the  edible  grains.  The  phosphoric  acid  is  usually 
present  in  combination  with  lime  as  calcium  phosphate. 

Guano  comes  mostly  from  islands  or  coasts  that  have  been  for  a  long 
time  without  human  residents,  and  where  birds  have  had  undisturbed  posses- 
sion. It  is  made  chiefly  of  the  excrements  of  birds  (sometimes  of  bats),  and 
owes  its  value  as  a  fertilizer  to  its  nitrogen  and  salts  of  phosphoric  acid.  But 
water,  from  the  rains,  percolating  through  it  carries  down  the  soluble  phos- 
phates into  the  underlying  material,  and  if  this  is  coral  rock  or  other  loose 


ROCKS:    THEIR   CONSTITUENTS  AND   KINDS. 


73 


2. 

3. 

4. 

5. 

59-50 

55-26 

32-46 

62-11 

9-46 

6-16i 

4-44 

13-24 
12-25 

30-94 

37-63 

58-07 

4-20 

— 

1-22 

•3-80 

— 

— 

— 

1-20 

2-12 

— 

— 

1-03 

0-50 

calcareous  deposit,  the  solution  converts  the  calcareous  rock  into  calcium 
phosphate,  which  goes  also  by  the  name  of  guano.  Isolated  excrements  in 
rocks  are  called  coprolites. 

Analyses  of  bones:  1,  2,  human  bones,  according  to  Frerichs;  3,  fish  (Haddock), 
according  to  Dumenil ;  4,  Shark  (Squalus  cornubicus),  according  to  Marchand  ;  5,  fossil 
bear,  id.  :  — 

1. 

Calcium  phosphate 50*24 

Calcium  carbonate 11-70 

Calcium  sulphate 

Organic  substance 38-22 

Traces  of  soda,  etc — 

Calcium  fluoride ." .       — 

Magnesium  phosphate — 

In  No.  4,  a  little  silica  and  alumina  are  included  with  the  fluoride.  No.  5  contains  also 
silica  2-12,  and  oxides  of  iron  and  maganese,  etc.,  3*46. 

The  enamel  of  teeth  contains  85  to  90  per  cent  of  calcium  phosphate,  2  to  5  of  calcium 
carbonate,  and  5  to  10  of  organic  matters.  Fish-scales  from  a  Lepidosteus  afforded  Fr6my 
40  per  cent  of  organic  substance,  51-8  of  phosphate  of  lime,  7 '6  of  magnesium  phosphate, 
and  4-0  of  calcium  carbonate.  Other  fish-scales  contained  but  a  trace  of  the  magnesium 
phosphate  and  more  of  organic  matters. 

T.  S.  Hunt  obtained  for  the  composition  of  the  shell  of  Lingula  ovalis,  Calcium  phos- 
phate 85-79,  calcium  carbonate  11-75,  magnesium  phosphate  2-80  =  100-34.  The  shells  of 
a  fossil  Obolus  afforded  Kupffer  the  composition  nearly  of  a  fluor-apatite  (Amer.  Jour. 
Sci.,  III.  vi.  146);  and  the  phosphatic  shells  are  thin,  somewhat  horny  in  appearance,  and 
usually  become  black  on  fossilization. 

The  shell  of  a  Lobster  (Palinurus')  afforded  Fremy,  calcium  carbonate  49-0,  calcium 
phosphate  6-7,  organic  substance  44-3. 

Phosphatic  nodules,  possibly  coprolitic,  in  the  Lower  Silurian  rocks  of  Canada  (on 
River  Ouelle),  afforded  T.  S.  Hunt  (see  Amer.  Jour.  Sci.,  II.  xv.  and  xvii.),  in  one  case, 
calcium  phosphate  40-34,  calcium  carbonate  with  fluoride  5-14,  magnesium  carbonate  9-70, 
iron  peroxide  with  a  little  alumina  12-62,  sand  25-44,  moisture  2-13  =  95-37.  In  a  hollow 
cylindrical  body  from  the  same  region,  there  were  67-53  per  cent  of  phosphate. 

Analyses  of  coprolites.  —  Nos.  1  and  2  by  Gregory  and  Walker ;  3  and  4  by  Connell ; 
6  by  Quadrat ;  6  by  Rochleder  (a  coprolite  from  the  Permian)  :  — 


Calcium  phosphate 

Calcium  carbonate 

Silica 

Organic  material 

Magnesium  carbonate . . . 

Iron  sesquioxide 

Alumina 

Water 

Lime  of  organic  part 

Sodium  chloride . . 


1. 

2. 

3. 

4. 

5. 

6. 

Burdie- 
house. 

Fife- 
shire. 

Burdie- 
house. 

Burdie- 

house. 

Kosch- 
titz. 

Oberlan- 
genau. 

9-58 

63-60 

85-08 

83-31 

50-89 

15-25 

61-00 

24-25 

10-78 

15-11 

32-22 

4-57 

4-13 

trace 
3-38 

0-34 
3-95 

0-29 
1-47 

0-14 

7-38 

74-03 

13-57 

2-89 

— 

— 

— 

2-75 

6-40 

trace 

— 

— 

2-08 

— 

5-33 


100-01 


3-33  _  _  _  _ 

1-44 

1-96 

97-45       100-15       100-18        9943       100-00 


The  ashes  of  grass,  straw,  clover,  amounting  to  5  to  8  per  cent  of  the  dried  plant, 
afford  usually  5  to  15  per  cent  of  phosphoric  acid ;   and  those  of  the  seed  in  wheat, 


74 


STRUCTURAL  GEOLOGY. 


rye,  maize,  rice,  buckwheat  (the  amount  of  ash  2  per  cent  or  less)  affords  40  to  50 
per  cent;  of  leaves  of  walnut  (the  ash  7  to  7-72  per  cent),  21-1  per  cent  spring,  4  per 
cent  autumn;  of  beech  (ash  4-8  and  6-75  per  cent),  7-8  per  cent  summer,  4 -2  per  cent 
autumn  ;  wood  of  body  of  beech  (amount  of  ash  in  dried  0-65  per  cent),  5-3  per  cent ;  of 
small  wood  11-6  per  cent,  and  of  brush  12-3  per  cent ;  of  pine,  fir,  larch  (0-3  per  cent  of 
ash),  3-6  to  6  per  cent  of  phosphoric  acid. 

Carbonaceous.  —  The  carbonaceous  material  of  the  rocks  has  come,  as  has 
been  stated,  from  the  decomposition  of  plants  and  animals,  and  chiefly  the 
former.  Wood  contains  about  50  per  cent  of  carbon,  along  with  44  of  oxygen 
and  6  of  hydrogen.  Peat  is  woody  material  altered  part  way  toward  coal, 
and  sometimes,  wholly  so  in  places.  Brown  coal  is  coal  that  has  a  dark 
brownish  powder.  Bituminous  coal  has  a  black  powder,  and  burns  with  a 
bright  flame ;  anthracite  burns  with  little  flame.  Each  contains  some  of  the 
oxygen  of  the  original  wood,  the  anthracite  the  least. 

Mineral  oil  and  mineral  gas  consist  of  carbon  and  hydrogen  alone,  oxygen 
being  wholly  absent.  They  are  the  source  of  the  flame  of  bituminous  coal ; 
they  do  not,  however,  exist  in  the  coal,  for  when  the  coal  is  digested  in 
a  solvent  of  the  oil,  as  benzine,  almost  no  oil  is  taken  up ;  the  oil  or  gas  is 
produced  by  the  heat  from  a  compound  present  in  the  coal.  Other  carbona- 
ceous substances  of  similar  origin  are  asphalt,  an  oxidized  hydrocarbon, 
mineral  resins,  etc.  Moreover,  among  the  mineral  resins  are  one  or  two 
which  contain  sulphur. 

Alumina,  magnesia)  iron,  soda,  potash,  sulphur,  etc.  —  A  few  of  the  coal- 
making  plants,  especially  the  Lycopods,  contain  much  alumina  in  their  ash, 
and  magnesia,  iron,  potash,  soda,  exist  in  many  plants.  In  the  decomposi- 
tion of  buried  plants,  these  materials  are  partly  dissolved  out  and  carried 
away  by  waters,  and  partly  contributed  to  rocks.  The  following  are  some 
analyses  of  the  ash  of  plants  :  — 

Analyses  of  the  ash  of  Lycopods  (1,  2),  Ferns  (3  to  6),  Equiseta  (7,  8),  Conifer  (9), 
Moss  of  the  genus  Sphagnum  (10),  and  an  Ilex  (11)  :  — 


1. 

2. 
3. 

Lye.  clavatum  .  . 
Lye.  clavatum  .  . 
Aspl.  filix  

KO 
31-90 
25-69 
455 

NaO 
2-68 
1-74 
5-2 

CaO 
4-13 
7-96 
7-9 

MgO 
5-89 
6-51 
7-4 

Fe203 
6-00 
2-30 
1-5 

Mn304 
2-53 

4. 
5. 
6. 
7. 
8, 
9. 
10. 

11. 

Aspid.  filix  
Osm.spicant.  .  .  . 
Pteris  aquilina  .  . 
Eq.  arvense  
Eq.  Telmateia.  .  . 
Pinus  abies  
Sphag.  commune 
Ilex  cassine  

39-80 
23-65 
19-35 
19-16 
8-01 
12-84 
.  8-02 
27-02 

5-31 
3-33 
4-78 
0-48 
0-63 
5-64 
12-40 
0-47 

18-74 
4-09 
12-55 
17-20 
8-63 
58-27 
3-17 
10-99 

8-28 
6-47 
2-30 
2-84 
1-81 
2-81 
4-92 
16-59 

0-97 
1-17 
3-94 
0-72 
1-42 
1-60 
6-35 
0-26 

tr. 

tr. 
1-73 

A1203      PO5  SO3 

22-20     7-30  3-55 

26-65    5-36  4-90 

—  20-0  6-8 

—  2-56  5-40 
1-76  1-29 
5-15  1-77 
2-79  10-18 

—  1-37  2-83 
tr.       2-60  1-60 
5-89     1-06  4-33 

—  3-34  2-50 


8iO2 
13-01 
13-94 

2-2 

4-38 
53-00 
43-65 
41-73 
70-64 
12-55 
41-69 

1-32 


Cl 

3-13 
4-6 

14-72 
5-82 
6-20 
6-26 
5-59 
2-06 

12-09 
0-66 


Analysis  1  is  by  Ritthausen  ;  2,  Aderholt ;  3,  A.  Weinhold  ;  4,  Struckmann ;  5,  6, 
9,  Malaguti  &  Durocher ;  7,  8,  E.  Wittig  ;  10,  H.  Vohl ;  11,  F.  P.  Venable. 

In  the  analyses  that  have  been  made  of  Lycopods,  the  amount  of  ash  is  3-2  to  6  per 
cent  in  weight  of  the  dried  plant ;  of  Ferns,  2-75  to  7-56  per  cent ;  of  Equisetum  arvense, 


ROCKS  :    THEIR   CONSTITUENTS   AND   KINDS.  75 

18-71  per  cent;  of  Eq.  Telmateia,  26-75  per  cent;  of  Conifers,  mostly  less  than  2  per 
cent;  of  Fungi,  3-10  to  9-5  per  cent ;  of  Lichens,  1-14  to  17  per  cent  (the  last  in  Clado- 
nia),  but  mostly  between  1-14  and  4-30  per  cent.  In  Lycopodium  dendroideum,  Hawes, 
in  his  analyses  (p.  362),  found  3-25  per  cent  of  ash;  in  L.  complanatum,  5-47  per  cent, 
and  in  Equisetum  hyemale,  11-82  per  cent. 

Lycopodium  chamcecyparissus  afforded  Aderholt  51  -85  per  cent  of  alumina  ;  or,  when 
without  spores,  57-36  per  cent ;  while  Ritthausen  obtained  39-97  alumina  for  this  species, 
and  37  -87  for  L.  complanatum.  In  Lycopods  the  silica  constitutes  10  to  14  per  cent  of 
the  ash.  In  the  ash  of  Mosses  have  been  found  8  to  23-58  per  cent  of  potash,  4  to  16  of 
silica,  1-06  to  6-56  of  phosphoric  acid,  4-9  to  10-7  of  magnesia.  Among  Ferns,  the  amount 
of  ash,  so  far  as  determined,  varies  from  5  to  8  per  cent. 

The  ash  of  Fungi  affords  21  to  54  per  cent  of  potash,  0-36  to  11-8  of  soda,  1-27  to  8 
of  magnesia,  15  to  60  of  phosphoric  acid,  and  0  to  15-4  of  silica.  Among  Lichens,  the 
ash  of  Cladonia  rangiferina  contains  70-34  per  cent  of  silica;  of  other  species,  less,  down 
to  0-9  per  cent. 

Trapa  natans,  of  bogs,  in  Europe,  affords  13  to  25  per  cent  of  ash ;  and  25  per  cent 
of  this  is  oxide  of  iron  (Fe203)  with  a  little  oxide  of  manganese.  Of  the  ash  of  the  fruit 
scales,  over  60  per  cent  is  oxide  of  iron.  The  Ilex  cassine  of  North  Carolina  (the  leaves 
of  which  produced  the  Black  Drink  of  the  Indians)  afforded,  from  leaves  collected  in  May 
and  dried,  5-75  per  cent  of  ash,  which  is  remarkable  (No.  11,  above)  for  the  amount  of 
potash  and  magnesia.  Another  Holly  afforded  11-39  of  magnesia,  and  12-34  of  lime. 

Ash  of  bean  straw  (6  to  7  per  cent  of  dried)  affords  35  to  45  per  cent  of  potash ;  of 
buckwheat  straw  (6-15  per  cent),  46-6  of  potash  ;  of  oat  straw  (5-1  per  cent),  22  per  cent 
of  potash. 

Soda  is  a  prominent  constituent  in  the  ash  of  Sea-weeds  (Fuci"),  analysis  giving  14-39 
per  cent  of  ash,  and  in  this,  24  of  soda,  with  14-5  of  potash.  Scirpus  (bulrush)  afforded 
8 -65  per  cent  ash,  and  in  it  10-3  per  cent  of  soda  with  9-7  of  potash;  and  Juncus,  6-6 
of  soda  to  36-6  of  potash.  The  ash  of  beets  contains  14-8  per  cent  of  soda;  of  carrots, 
22-1  per  cent ;  but  grasses  generally  1  to  5  per  cent  of  soda. 

The  amount  of  sulphur  in  the  ash  of  grasses,  straws,  and  woods  is  usually  1  to  2-5  per 
cent ;  in  that  of  Fucus,  18  per  cent ;  in  that  of  common  vegetables,  3  to  6  per  cent.  The 
amount  of  chlorine  in  the  ash  of  grasses  is  3  to  5-5  per  cent ;  in  that  of  vegetables,  3  to  11 
per  cent ;  in  that  of  Fucus,  10  per  cent ;  in  that  of  Juncus,  14-2  per  cent ;  in  that  of  woods, 
usually  less  than  1  per  cent.  (These  percentages  are  taken  from  tables  in  Johnson's  How 
Crops  Grow,  New  York,  1887.) 

KINDS  OF  ROCKS. 

(1)  General  explanations.  —  Rocks  are  conveniently  divided  into  two 
general  sections :  (1)  the  Fragmental  or  Clastic,  and  (2)  the  Crystalline. 

For  the  study  of  even  the  coarser  kinds  of  rocks,  the  geological  student  should  have 
a  pocket  lens.  In  investigation,  it  will  generally  be  necessary  to  supplement  this  with 
a  compound  polariscope-microscope  made  especially  for  the  study  of  rocks ;  but  a  thor- 
ough study  of  the  elements  of  petrology  is  required  for  the  satisfactory  use  of  the  latter 
instrument. 

FRAGMENTAL  ROCKS.  —  The  fragmental  rocks  are  those  that  have  been 
made  out  of  fragments  of  older  rocks.  They  are  also  called  clastic  rocks, 
from  the  Greek  for  to  break.  All  the  sand,  gravel,  stones,  earth,  mud,  and 
clay  of  the  world  is  worn  or  pulverized  or  decomposed  rock.  Each  grain, 
however  small  or  large,  may  hence  be  spoken  of  as  a  fragment  of  preexist- 
ing rocks.  The  rocks  of  an  age  are  mostly  made  out  of  the  detritus  (worn- 
out  rocks)  of  preceding  time. 


76  STRUCTURAL   GEOLOGY. 

To  appreciate  the  nature  and  qualities  of  fragmental  material,  the  student 
should  go  to  the  hills  where  sand  and  gravel  are  dug ;  to  the  sea-beaches 
where  the  waves  are  at  their  grinding  and  assorting  work,  or  to  the  estuaries 
where  mud-flats  and  sand-flats  have  been  made  by  their  greater  action ;  to 
the  river-valleys,  where  plunging  streams  are  at  their  abrading  and  destroy- 
ing work,  or  where  quieter  streams  are  bordered  by  terraces  of  sand,  or 
gravel,  or  loam,  or  clay.  All  is  fragmental  material ;  and  all  these  results 
of  attrition  and  partial  decomposition  may  be  included  under  the  four 
divisions  of  (1)  sand,  (2)  gravel  (or  a  mixture  of  stones  and  sand),  (3)  earth 
or  mud  (according  as  it  is  wet  or  not),  and  (4)  clay.  The  last,  the  material 
of  brick  and  pottery,  is  plastic  when  wet,  and  feels  a  little  greasy.  Mud  of 
the  finest  kind  is  usually  more  or  less  pure  clay. 

Fragmental  deposits  are  made  up  of  successive  beds  or  layers ;  that  is, 
are  stratified  (using  a  term  from  the  Latin  stratum,  a  bed).  They  are  also, 
for  the  most  part,  sedimentary  beds,  the  sand  and  earth  deposited  by  water 
being  its  sediment;  and  hence  they  are  often  called  sediments.  The  waters 
that  deposited  the  sediment  and  made  the  stratified  accumulations  were 
mostly  those  of  the  ocean,  or  of  rivers  or  lakes ;  and  sea-border,  fluvial,  and 
lacustrine  formations  are  illustrations  therefore  of  fragmental  deposits. 

CRYSTALLINE  KOCKS. — Nearly  all  substances  crystallize  on  passing  to 
the  solid  state  from  a  previous  state  of  either  fusion,  solution,  or  vapor,  and 
many  without  fusion  if  subjected  to  long-continued  heat.  The  grains  of  a 
massive  crystalline  rock  are,  in  the  main,  or  wholly,  imperfect  crystals.  They 
are  generally  angular  in  form ;  and  when  so,  it  is  usually  because  of  the 
cleavages  of  the  constituent  mineral  grains.  Being  crowded  together,  they 
very  seldom  have  the  external  planes  of  crystals.  Granite  and  crystalline 
limestone  (or  ordinary  white  marble)  are  examples.  In  crystalline  lime- 
stone, all  the  grains  are  angular  and  glisten,  owing  to  the  cleavage-surfaces. 
In  granite,  those  of  two  of  the  constituent  minerals  show  sparkling  cleavage- 
surfaces,  but  the  third,  quartz,  is  without  cleavage.  When  the  grains  are 
distinctly  visible  without  a  glass,  the  texture  is'  described  as  macroscopic ;  if 
undistinguishable,  the  texture  is  microscopic,  or  aphanitic. 

Crystalline  rocks  are,  to  a  large  extent,  igneous  or  eruptive  rocks ;  that  is, 
they  have  become  crystalline  masses  from  a  state  of  fusion,  as,  for  example, 
lavas  and  the  many  kinds  of  igneous  rocks.  Others  have  become  crystalline 
by  heat  without  fusion,  with  or  without  attending  change  in  composition ;  for 
example,  a  massive  limestone  has  thus  been  changed  by  simply  long-continued 
heat  to  a  crystalline  limestone  or  marble,  granitic  sandstone  to  granite  or 
gneiss,  and  so  on.  Such  rocks  are  called  metamorphic  rocks.  Fragmental 
rocks  have  been  thus  metamorphosed  on  a  large  scale  during  times  of  moun- 
tain-making. Metamorphic  rocks  have  sometimes  been  subjected  to  a  second 
partial  or  complete  metamorphism,  and  igneous  rocks  occur  altered  in  like 
manner.  Crystalline  rocks  are  usually  mere  mixtures,  like  the  fragmental, 
as  they  consist  of  one,  two,  or  more  minerals  in  various  proportions.  If  of 


HOCKS  :    THEIR    CONSTITUENTS    AND   KINDS.  77 

more  than  one,  the  prominent  distinctions  are  usually  based  on  the  two  most 
characteristic ;  and  the  others  are  considered  as  accessory  minerals,  and  are 
made  to  distinguish  varieties. 

The  following  are  distinctions  among  crystalline  rocks,  based  on  texture 
and  structure :  — 

1.  Granitoid.  —  Granular-crystalline,  like  ordinary  granite. 

2.  Micro-granitic.  —  Like  granite,  but  very  fine  in  grain. 

3.  Micro-crystalline.  —  Compact,  and  so  fine  in  texture  as  barely  to  glisten 
over  a  surface  of  fracture. 

4.  Porphyritic. —  Having  one  of   the  minerals  of  the  rock  in  distinct 
crystals   (Fig.  58).     The  original  porphyry  of  geology  included  a  red  por- 
phyry (from  Egypt),  a  compact  red  rock,  finely 

spotted  with  pale  feldspar  (orthoclase)  crystals  ; 
and  a  green  porphyry  —  the  Oriental  verd-antique 
—  with  rather  large  crystals  of  whitish  labradorite, 
from  western  Greece.  The  rocks,  although  alike 
in  being  porphyritic,  are  not  of  the  same  species, 
but  are  porphyritic  varieties  of  different  species,  as 
described  beyond. 

The  mineral  in  crystals  in  a  porphyritic  rock 

may  be  any  feldspar,  or  it  may  be  augite,  leucite,  quartz,  or  some  other 
species ;  and  whatever  the  mineral,  the  crystals  are  called  plienocrysts,  from 
the  Greek  for  "  visible  crystals,"  a  term  proposed  by  J.  P.  Iddings.  The  kind 
of  mineral  is  indicated  by  the  terms  ortJiophyric,  if  orthoclase ;  labradophyric, 
if  labradorite  ;  augitophyric,  if  augite  ;  leucitophyric,  if  leucite  ;  quartzophyric, 
if  quartz ;  spherophyric,  if  containing  spherical  concretions,  etc. 

5.  Foliated.  —  Having  the  cleavage-structure  of  slate,  as  in  extreme  cases 
of  foliation;  or  having  an  arrangement  of  the  minerals,  especially  of  any 
foliated  mineral  like  mica,  approximately  in  planes,  so  that  the  rock  has 
the  appearance  of   being  stratified,  and  often  breaks  easily  into  slates  or 
sheets.     The  slaty,  and  all  schistose,  structure,  to  the  faintest,  is  here  in- 
cluded.    The  planes  of  foliation  are  either  pressure-made  planes,  or  corre- 
spond to  planes  of  bedding  or  stratification. 

6.  Fluidal.  —  In  igneous  rocks,  having  the  material  of  the  rock  or  of 
portions  of  it  in  parallel  lines  or  bands  and  looking  as  if  due  to  the  flow  of 
the  rock  while  melted. 

1.  Glassy,  glass-bearing.  —  Melted  rocks,  when  cooled  rapidly,  often 
become  glass  at  surface  instead  of  rock ;  and  in  some  cases  all  gradations 
occur  in  the  mass  of  an  igneous  rock  between  glass  with  microscopic  stony 
points,  or  microlites,  and  stone  with  microscopic  glassy  particles.  Lavas 
have  usually  particles  in  a  glassy  state  among  the  stony  particles,  which  a 
microscopic  study  of  the  rock  will  detect. 


78  STRUCTURAL   GEOLOGY. 

8.  Vesicular.  —  Having  small  cavities  in  the  rock  (igneous),  made  usually 
by  steam,  as  in  many  lavas. 

9.  Scoriaceous.  —  Having  vesicles  in  so  great  abundance  that  they  make 
the  chief  part  of  the  mass  like  much  furnace  slag,  as  a  scoriaceous  lava. 

10.  Amygdaloidal  (from  amygdalum,  an  almond). — Having  the  vesicles 
(which  are  often  almond-shaped)  filled  with  minerals  foreign  to  the  rock, 
such  as  quartz,  calcite,  and  the  zeolites.     Trap,  or  doleryte,  and  related  basic 
eruptive  rocks  are  often  amygdaloidal. 

The  following  are  other  terms  used  in  describing  either  fragmental  or  crystalline 
rocks :  — 

Quartzose.  —Consisting  of  quartz;  containing  much  quartz. 

Calcareous.  —  Consisting  of  limestone  (calcite)  ;  containing  much  calcite. 

Ferruginous.  —  Containing  much  iron  oxide. 

Argillaceous  (from  argilla,  clay).  —  Made  of  more  or  less  hardened  clay  or  fine  mud  ; 
containing  clayey  material. 

Pyritiferous.  —  Containing  pyrite. 

Granitic.  — Made  of  granite  sand,  or  gravel. 

(2)  Descriptions  of  rocks.  —  The  kinds  of  rocks  are  described  under  the 
heads  of  — 

LIMESTONES,  or  CALCAREOUS  EOCKS. 
FRAGMENT AL  ROCKS,  NOT  CALCAREOUS. 
CRYSTALLINE  EOCKS,  EXCLUSIVE  OF  LIMESTONES. 

In  the  names  of  rocks,  the  termination  ite  is  here  changed  to  yte,  as  done  in  the 
author's  System  of  Mineralogy  (1808),  in  order  to  distinguish  them  from  the  names 
of  minerals.  Granite  is  excepted. 

LIMESTONES,  NOT  CRYSTALLINE. 

MASSIVE  LIMESTONE.  —Compact  uncrystalline  ;  color  whitish,  dull  gray,  bluish  gray, 
brownish,  and  black.  Texture  compact  to  earthy,  sometimes  semi-crystalline.  Consists 
essentially  of  calcite  or  calcium  carbonate  (page  68),  but  is  often  impure  with  clay  or 
sand. 

Most  limestones  are  of  organic  origin.  A  dark  or  black  color  is  usually  owing  to 
some  carbonaceous  material  present,  derived  from  the  decomposition  of  the  plants  or 
animals  of  the  waters  in  which  they  were  formed.  When  burnt,  limestone  (CaO3C)  becomes 
quicklime  (CaO),  through  loss  of  carbonic  acid  (C02)  ;  and,  at  the  same  time,  all 
carbonaceous  materials  are  burnt  out,  and  the  color,  when  it  is  owing  solely  to  these, 
becomes  white.  A  limestone  made  of  pebbles  of  limestone  is  called  a  limestone  conglom- 
erate, as  that  of  the  Potomac. 

MAGNESIAN  LIMESTONE,  DOLOMYTE  (page  68).  — Calcium-magnesium  carbonate.  Not 
distinguishable  in  color  or  texture  from  ordinary  limestone.  Much  of  the  common  lime- 
stone of  the  United  States  is  magnesian.  While  some  of  the  magnesian  limestone  is  true 
dolomite  (or  has  the  calcium  and  magnesium  in  the  atomic  proportion  1:1),  much  is  a 
mixture  of  calcite  and  dolomite. 

In  some  limestones  the  fossils  are  magnesian,  while  the  rock  is  common  limestone. 
Thus,  an  orthoceras  in  the  Trenton  limestone  of  Bytown,  Canada  (which  is  not  mag- 
nesian), afforded  T.  S.  Hunt  calcium  carbonate  56'00,  magnesium  carbonate  37*80,  iron 


ROCKS  :    THELR   CONSTITUENTS   AND  KINDS.  79 

carbonate  5-95  =  99-75.  The  pale  yellow  veins  in  the  Italian  black  marble,  called 
"  Egyptian  marble,"  are  dolomite,  according  to  Hunt. 

HYDRAULIC  LIMESTONE. — A  limestone  containing  20  to  30  per  cent  of  clay,  and 
affording  a  quicklime,  the  cement  from  which  will  "  set "  under  water.  It  is  often  mag- 
nesian.  An  analysis  of  a  kind  from  Rondout,  N.  Y.,  afforded  carbonic  acid  34-20,  lime  25-50, 
magnesia  12-35,  silica  15-37,  alumina  9-13,  sesquioxide  of  iron  2-25.  In  making  ordinary 
mortar,  quartz  sand  is  mixed  with  pure  quicklime  and  water,  and  the  chemical  combina- 
tion is  mainly  that  between  the  water  and  lime,  together  with  an  absorption  subsequently 
of  carbonic  acid.  Evaporation  to  dry  ness  is  necessary  to  hardening.  With  ' '  hydraulic 
cement,"  silica  and  alumina  (that  of  the  clay)  are  disseminated  through  the  lime,  and 
hence  these  ingredients  enter  into  chemical  union  with  the  lime  and  water,  and  make  a 
much  firmer  cement,  and  one  which  "sets"  under  water.  Portland  cement  is  made  by 
mixing  70  per  cent  of  chalk  with  30  of  fine  mud  from  the  Thames. 

OOLYTE.  —  Limestone,  either  magnesian  or  not,  consisting  of  minute  concretionary 
spherules ;  looks  like  the  petrified  roe  of  fish,  and  hence  the  name,  from  the  Greek  056?, 
egg- 

CHALK.  —  A  white,  earthy  limestone,  easily  leaving  a  trace  on  a  board.  Composi- 
tion, the  same  as  that  of  ordinary  limestone. 

MARL.  —  A  clay  containing  a  large  proportion  of  carbonate  of  lime  —  sometimes  40 
to  50  per  cent.  If  the  marl  consists  largely  of  shells  or  fragments  of  shells,  it  is  called 
shell-marl.  Marl  is  used  as  a  fertilizer ;  and  beds  of  clay  or  sand  that  can  be  so  used  are 
often  in  a  popular  way  called  marl. 

SHELL  LIMESTONE,  CORAL  LIMESTONE. — A  rock  made  out  of  shells  or  corals. 

TRAVERTINE. — A  massive  limestone,  formed  by  deposition  from  calcareous  waters, 
and  largely  through  the  agency  of  fresh-water  Algae,  as  at  the  Yellowstone  Park  (W.  H. 
Weed).  But  part  is  a  deposit  from  solution.  The  rock  abounds  on  the  river  Anio,  near 
Tivoli,  and  St.  Peter's,  at  Rome,  is  constructed  of  it.  The  name  is  a  corruption  of 
Tiburtine. 

CRYSTALLINE  LIMESTONE. 

STALAGMITE,  STALACTITE,  DRIPSTONE.  —  Depositions  from  waters  trickling  through 
the  roofs  of  limestone  caverns  form  calcareous  cones  and  cylinders  pendent  from  the 
roofs,  which  are  called  stalactites,  and  incrustations  on  the  floors,  which  are  called 
stalagmite,  and  sometimes  also  dripstone.  The  waters,  filtering  down  from  the  overlying 
soil,  contain  a  little  carbonic  acid  or  some  organic  acid,  and  are  thus  enabled  to  dissolve 
the  limestone,  which  is  deposited  again  on  evaporation.  The  layers  of  successive  deposi- 
tion are  usually  distinct,  giving  the  material  a  banded  appearance. 

GRANULAR  LIMESTONE,  CALCYTE  (statuary  marble).  —  Limestone  having  a  crystal- 
line granular  texture,  white  to  gray  color,  often  clouded  with  other  colors  from  impurities. 
It  is  a  metamorphic  rock.  Its  impurities  are  often  mica  or  talc,  tremolite,  white  or  gray 
pyroxene  or  scapolite ;  sometimes  serpentine,  through  combination  with  which  it  passes 
into  ophiolyte  (p.  89);  occasionally  chondrodite,  apatite,  corundum. 

Varieties. — a.  Statuary  Marble;  pure  white  and  fine  grained,  b.  Ornamental 
and  Architectural  Marble  ;  coarse  or  fine,  white,  and  mottled  of  various  colors,  and,  when 
good,  free  not  only  from  iron  in  the  form  of  pyrite,  but  also  from  iron  or  manganese  in 
the  state  of  carbonate  with  the  calcium,  and  also  from  all  accessory  minerals,  even  those 
not  liable  to  alteration,  and  especially  those  of  greater  hardness  than  the  marble,  which 
would  interfere  with  the  polishing.  c.  Verd-antique,  or  ophiolyte.  d.  Micaceous. 
e.  Tremolitic ;  contains  bladed  crystallizations  of  the  white  variety  of  hornblende  called 
tremolite.  f.  Graphitic;  contains  graphite  in  iron-gray  scales  disseminated  through  it. 
g.  Chloritic;  contains  disseminated  scales  of  chlorite,  h.  Chondroditic ;  contains  dis- 
seminated chondrodite  in  large  or  small  yellow  to  brown  grains. 

DOLOMYTE. — Not  distinguishable  by  the  eye  from  granular  limestone.     The  dolo- 


80  STRUCTURAL   GEOLOGY. 

myte,  which  is  calcitic  (a  mixture  of  calcite  and  dolomite),  is  apt  to  crumble  from 
weathering,  because  the  calcite  is  the  most  soluble,  and  becomes  removed  by  nitrating 
waters. 

As  the  kinds  of  fragmental  materials  which  the  rocks  afford  over  the  earth  are  either 
sand,  gravel,  earth,  or  mud,  and  clay,  the  kinds  of  fragmental  rocks  are  few. 

FRAGMENTAL  ROCKS,  NOT  CALCAREOUS. 

CONGLOMERATE.  —  A  consolidated  gravel-bed,  consisting  of  a  mixture  of  pebbles,  or 
fragments  of  rocks,  and  finer  material,  a.  If  the  pebbles  are  rounded,  it  is  called  pudding- 
stone;  b.  if  angular,  breccia.  Conglomerates  are  named,  according  to  their  constituents, 
siliceous  or  quartzose,  granitic,  calcareous. 

GRIT,  GRIT-ROCK. — A  hard,  gritty  rock,  consisting  of  coarse  quartz  sand  and  small 
pebbles  ;  called  also  millstone  grit,  because  used  sometimes  for  millstones. 

SANDSTONE.  —  A  rock  made  of  sand  ;  a  consolidated  sand-bed.  There  are  siliceous, 
granitic,  micaceous,  feldspathic,  calcareous  sandstones,  according  to  the  character  of  the 
material.  They  are  thick-bedded  or  thin-bedded,  according  to  the  thickness  of  the  beds ; 
laminated  when  divisible  into  laminae  or  slabs ;  shaly  when  splitting  into  thin  pieces  or 
sheets  like  shale  or  an  imperfect  slate.  There  are  also  compact,  friable,  argillaceous, 
gritty,  ferruginous,  concretionary,  massive,  flexible,  and  other  kinds.  Grindstones  are 
made  of  an  even-grained,  rather  friable  sandstone.  Hard,  siliceous  sandstones,  grit,  and 
conglomerate,  in  regions  of  metamorphic  rocks,  are  called  quartzyte  (page  82).  The 
Arkansas  Novaculite,  or  whetstone,  is  an  exceedingly  fine-grained  sandstone  microscopi- 
cally porous  through  the  loss  by  infiltrating  waters  of  disseminated  calcareous  particles 
(L.  S.  Griswold). 

SAND-ROCK.  —  A  rock  made  of  sand  of  any  kind,  especially  if  not  siliceous  or  granitic. 
A  calcareous  sand-rock  is  one  made  of  calcareous  sand,  as  pulverized  corals  or  shells. 

SHALE.  —  Consolidated  mud  or  clay  ;  a  soft,  fragile,  slaty,  argillaceous  rock.  Shales 
are  gray  to  black  in  color,  and  sometimes  dull  greenish,  purplish,  reddish. 

Varieties.  —  a.  Carbonaceous  shale;  black  and  impregnated  with  coaly  material, 
yielding  mineral  oil  or  related  bituminous  matters  when  heated  (Brandschiefer  in  German), 
b.  Alum  shale  ;  impregnated  with  alum  or  pyrites,  usually  a  crumbling  rock.  The  alum 
proceeds  from  the  alteration  of  pyrite,  or  an  allied  iron  sulphide,  in  the  rock. 

ARGILLYTE,  or  Clay-slate  {Phyllyte}. — A  slaty  rock,  like  shale,  but  differing  in 
breaking  usually  into  thin  and  even  slates  or  slabs.  Hoofing  and  writing  slates  are  exam- 
ples. It  is  sometimes  thick-laminated.  Moreover,  unlike  shale,  it  occurs  in  regions  of 
metamorphic  rocks,  and  often  graduates  into  hydromica  and  mica  schists.  It  graduates 
often  into  hard,  thick-layered  sandy  beds,  which  used  to  be  called  gray  wacke. 

TUFA.  —  Consists  of  comminuted  volcanic  sand  and  small  fragments  of  lavas,  more 
or  less  altered.  Usually  of  a  gray,  yellowish  brown,  or  brown  color,  sometimes  red.  The 
tufa  made  from  those  igneous  rocks  that  contain  pyroxene  is  usually  yellowish  brown  01 
brown  in  color  (sometimes  red)  (often  called  wacke)  ;  and  that  made  from  the  feldspathift 
igneous  rocks,  trachyte,  pumice,  and  the  like,  is  of  an  ash-gray  color,  or  of  other  light 
shades.  The  finer  deposits  are  often  called  ash-beds.  Since  volcanic  ashes  are  often  very 
widely  distributed  by  the  winds,  they  make  deposits  beyond  the  limits  of  the  volcano, 
over  the  land,  or  lakes,  or  the  sea-bottom  ;  and  sometimes  the  deposits  have  great  thick- 
ness. Pozzuolana  is  a  light-colored  tufa,  found  in  Italy,  near  Rome,  and  elsewhere,  and 
used  for  making  hydraulic  cement.  Volcanic  sand,  or  peperino,  is  sand  of  volcanic  origin, 
either  the  "cinders"  or  "ashes"  (comminuted  lava)  formed  by  the  process  of  ejection, 
or  lava  rocks  otherwise  comminuted. 

CLAY.— Soft,  impalpable,  more  or  less  plastic  material,  chiefly  aluminous  in  com- 
position, white,  gray,  yellow,  red  to  brown  and  black  in  color. 


ROCKS  :    THEIR   CONSTITUENTS  AND   KINDS.  81 

Varieties.  —  a.  Kaolin  •  purest  unctuous  clay,  white,  and  when  impure,  of  other 
colors.  The  white  is  used  for  making  porcelain  by  mixing  with  pulverized  feldspar  and 
quartz,  also  for  giving  weight  and  body  to  writing-paper,  b.  Potter's  clay  ;  plastic,  free 
from  iron,  and  therefore  good  for  white  pottery  ;  mostly  unctuous  ;  usually  containing 
some  free  silica,  c.  Ferruginous,  Brick-clay ;  containing  iron  in  the  state  of  oxide  or 
carbonate,  and  consequently  burning  red,  as  in  making  red  brick  ;  generally  in  thin  layers, 
which  are  alternately  good  clay  and  fine  sand.  d.  Containing  iron  in  the  state  of  a 
silicate,  and  then  failing  to  turn  red  on  being  burnt,  as  the  clay  of  which  the  Milwaukee 
brick  are  made.  e.  Alkaline  and  Vitrifiable ;  containing  2-5  to  5  per  cent  of  potash  or 
potash  and  soda,  owing  to  the  presence  of  undecomposed  feldspar,  and  then  not  refrac- 
tory enough  for  pottery  or  fire-brick,  f.  Marly ;  containing  some  calcium  carbonate, 
g.  Carbonaceous,  Black,  Ampelite  ;  from  the  presence  of  lignitic  or  coaly  material, 
h.  Alum-bearing ;  containing  aluminous  sulphates,  owing  to  the  decomposition  of  iron 
sulphides  present. 

Rock-flour  is  rock  pulverized  to  extreme  fineness,  so  as  often  to  resemble  clay  although 
containing  very  little  of  it.  Feldspar  in  this  fine  state  is  present  in  much  clay.  Some 
rock-flour  consists  mainly  of  pulverized  quartz. 

ALLUVIUM,  SILT,  LCESS.  —  Alluvium  is  the  earthy  deposit  made  by  running  streams 
or  lakes,  especially  during  times  of  flood.  It  constitutes  the  flats  adjoining,  and  is  usually 
in  thin  layers,  varying  in  fineness  or  coarseness,  being  the  result  of  successive  depositions. 
Silt  is  the  same  material  deposited  in  bays  or  harbors,  wrhere  it  forms  the  muddy  bottoms 
and  shores.  Loess  is  an  earthy  deposit,  coarse  or  fine,  following  the  courses  of  valleys,  like 
alluvium,  but  without  division  into  thin  layers  ;  fertile  ordinarily  from  the  amount  of  vege- 
table matter  present,  and  containing  also  land  or  fresh-water  shells. 

Detritus  (from  the  Latin  for  worn)  is  a  general  term  applied  to  earth,  sand,  alluvium, 
silt,  gravel,  because  the  material  is  derived,  to  a  great  extent,  from  the  wear  of  rocks 
through  decomposing  agencies,  mutual  attrition  in  running  water,  and  other  methods. 

Soil  is  earthy  material,  mixed  with  the  results  of  vegetable  and  animal  decomposition, 
whence  it  gets  its  dark  color  and  also  a  chief  part  of  its  fertility. 

Till.  —  Unstratified  or  imperfectly  stratified  deposits  of  bowlders,  gravel,  and  clay, 
derived  from  a  continental  glacier.  Also  called  bowlder  clay.  Usually  firmly  compacted, 
owing  to  the  presence  of  clay  or  rock-flour  when  not  properly  consolidated. 

TRIPOLYTE  (Infusorial  Earth). — Resembles  clay  or  chalk,  but  is  a  little  harsh  be- 
tween the  fingers,  and  scratches  glass  when  rubbed  on  it.  Consists  chiefly  of  siliceous 
shells  of  Diatoms.  Forms  thick  deposits,  and  is  often  found  in  swamps  beneath  the 
peat  (see  page  153).  Occurs  sometimes  slaty,  as  at  Bilin,  Prussia;  and  also  hard,  from 
consolidation  through  infiltrating  waters.  Consists  of  silica  in  the  opal  or  soluble  state. 

CRYSTALLINE  ROCKS. 

The  descriptions  of  crystalline  rocks  are  arranged  under  the  following 
heads : — 

I.    SILICEOUS  ROCKS,  OR  THOSE  CONSISTING  MAINLY  OF  SILICA. 

II.     ROCKS    HAVING    AS    A    CHIEF    CONSTITUENT    ONE    OR    MORE    OF   THE  ALKALI-BEARING 

MINERALS,  FELDSPAR,  MICA,  LEUCITE,  NEPHELITE,  SODALITE.  —  In  the  first  three  of  the 
following  subdivisions,  potash-feldspar  is  present  as  a  distinctive  feature  ;  in  4,  leucite 
also  contains  a  potash-bearing  mineral ;  in  5  and  6  a  soda-lime  or  a  lime  feldspar  is 
characteristic. 

1.  Potash-Feldspar  and  Mica  Series. 

2.  Potash-Feldspar  and  Hornblende  or  Pyroxene  Series. 

3.  Potash-Feldspar  and  Nephelite  Rocks,  Hornblendic  or  not. 

4.  Leucite  Rocks,  Pyroxenic  or  not. 

5.  Soda-lime-Feldspar  and  Mica  Series. 

DANA'S  MANUAL  —  6 


82  STRUCTURAL   GEOLOGY. 

6.  Soda-lime-Feldspar  Series,  with  or  without  Hornblende  or  Pyroxene,  —  the  feldspar 
a  triclinic  species  of  the  series  from  albite  to  anorthite. 

III.  SAUSSURITE  ROCKS. —Alkali  (soda)  bearing,  but  containing  saussurite  in  place 
of  a  feldspar. 

IV.  WITHOUT  FELDSPAR,  OR  WITH  VERY  LITTLE. 

1.  Garnet,  Epidote,  and  Tourmaline  Rocks.- 

2.  Hornblende,  Pyroxene,  and  Chrysolite  Rocks. 

V.  HYDROUS  MAGNESIAN  AND  ALUMINOUS  ROCKS. 

I.    Siliceous  Rocks. 

QUARTZYTE,  GRANULAR  QUARTZ.  — A  siliceous  sandstone,  usually  very  firm,  occurring 
in  regions  of  metamorphic  rocks.  It  does  not  differ  essentially  from  the  harder  siliceous 
sandstones  of  other  regions.  Conglomerate  beds  are  sometimes  included. 

Varieties.  —  a.  Massive,  b.  Schistose,  c.  Micaceous  ("Greisen").  d.  Hydromica- 
ceous.  e.  Feldspathic,  and  sometimes  Porphyritic  (then  called  by  some,  Arkose). 
f.  Friable,  g.  Flexible  (Itacolumyte) .  h.  Andalusitic.  i.  Ottrelitic.  j.  Tourmalinic, 
containing  tourmaline,  k.  Gneissic,  it  occasionally  graduating  into  gneiss. 

SILICEOUS  SLATE  (Phthanyte) .  —  Schistose,  flinty,  not  distinctly  granular  in  texture. 
Sometimes  passes  into  mica  or  hydromica  schist. 

CHERT.  —  An  impure  flint  or  hornstone  occurring  in  beds  or  nodules  in  some  stratified 
rocks.  It  often  resembles  felsyte,  but  is  infusible.  Colors  various.  Sometimes  oolitic. 
Kinds  containing  iron  oxide  graduate  into  jasper  and  clay-ironstone. 

JASPER  ROCK.  —  Dull  red,  yellow,  brown,  or  green,  or  of  some  other  dark  shade, 
breaking  with  a  smooth  surface  like  flint.  Consists  of  quartz,  with  more  or  less  clay  and 
oxide  of  iron.  The  red  contains  the  oxide  of  iron  in  an  anhydrous  state,  the  yellow  in  a 
hydrous ;  on  heating  the  latter,  it  turns  red. 

BUHRSTONE. — A  cellular  siliceous  rock,  flinty  in  texture.  Used  for  millstones. 
Found  mostly  in  connection  with  Tertiary  rocks,  and  formed  apparently  from  the  action 
of  siliceous  solutions  removing  fossils  and  so  making  the  cavities.  The  best  is  from  near 
Paris,  France. 

FIORYTE  (Siliceous  Sinter,  Pearl  Sinter,  Geyserite}.  — Opal-silica,  in  compact,  porous, 
or  concretionary  forms,  often  pearly  in  luster;  made  by  deposition  from  hot  siliceous 
waters,  as  about  geysers  (geyserite},  or  through  the  decomposition  of  siliceous  minerals, 
especially  about  the  fumaroles  of  volcanic  regions.  Geyserite  is  abundant  in  Yellowstone 
Park,  about  the  Iceland  geysers,  and  in  the  New  Zealand  geyser  region. 

II.   Rocks  having  Alkali-bearing  Minerals  as  Chief  Constituents. 

1.    The  Potash-feldspar  and  Mica  Series. 

GRANITE.  —  Metamorphic  and  eruptive.  Consists  of  feldspar,  mica,  and  quartz ;  has 
no  appearance  of  layers  in  the  arrangement  of  the  mica  or  other  ingredients.  The 
quartz  usually  grayish  or  smoky,  glassy,  and  without  any  appearance  of  cleavage.  The 
feldspar  commonly  whitish  or  flesh-colored,  less  glassy  than  the  quartz,  and  cleavable  in 
two  directions  ;  the  mica  in  very  cleavable  scales. 

Metamorphic  granite  is  common  in  Connecticut  and  other  parts  of  New  England, 
where  it  may  be  often  seen  graduating  into  gneiss,  or  in  alternating  layers  with  it. 

Varieties.  — There  are,  A,  Muscovite-granites ;  B,  Muscovite  and  Biotite  granites ; 
C,  Biotite-granites ;  D,  Hydromica  granite.  The  most  of  the  following  varieties  occur 
under  each  except  the  hornblendic,  which  is  usually  a  Biotite  or  Muscovite  and  Biotite 
granite,  a.  Common  or  ordinary  granite.  Color,  grayish  or  flesh-colored,  according  as 
the  feldspar  is  white  or  reddish,  and  dark  gray  when  much  black  mica  is  present. 
Varies  in  texture  from  fine  and  even  to  coarse  ;  sometimes  the  mica,  feldspar,  and  quartz 


BOCKS:   THEIR   CONSTITUENTS   AND   KINDS.  83 

—  especially  the  two  former  —  in  large  crystalline  masses,  b.  Porphyritic  ;  has  the  ortho- 
clase  in  defined  crystals,  and  may  be  (a)  small-porphyritic,  or  (/3)  large-porphyritic,  and 
have  the  base  (7)  coarse  granular,  or  (5)  fine,  and  even  subaphanitic.  c.  Albitic ;  con- 
tains some  albite,  which  is  usually  white,  d.  Oligoclase  granite  (Miarolyte) ;  contains 
oligoclase.  e.  Microcline  granite,'  contains  the  potash  triclinic  feldspar,  microcline. 
f.  Hornblendic ;  contains  black  or  greenish  black  hornblende,  along  with  the  other  con- 
stituents of  granite,  g.  Black  micaceous  granite ;  consists  largely  of  mica,  with  defined 
crystals  of  feldspar  (porphyritic),  and  but  little  quartz,  h.  Chloritic.  i.  Zirconitic. 
j.  lolitic.  k.  Spherophyric  or  globuliferous ;  contains  concretions  which  consist  of  mica, 
or  of  feldspar  and  mica.  1.  Gneissoid  ;  a  granite  in  which  there  are  traces  of  stratification  ; 
graduates  into  gneiss. 

GRANULYTE  (Leptynyte).  — Metamorphic  and  eruptive.  Like  granite,  but  containing 
no  mica,  or  only  traces. 

Varieties.  —  a.  Common  granulyte  ;  white  and  usually  fine  granular,  b.  Flesh- 
colored;  usually  coarsely  crystalline,  granular,  and  flesh-colored,  c.  Garnetiferous. 

d.  Hornblendic;  containing  a  little  hornblende  —  a  variety  that  graduates  into  syenyte. 

e.  Magnetitic ;  containing  disseminated  grains  of  magnetite,    f.   Graphic;  quartzophyric 
(Pegmatyte),  the  quartz  looking  like  Persian  cuneiform  characters  over  the  cleavage- 
surface  of  the  feldspar  ;  sometimes  coarse  crystallizations  of  mica. 

GNEISS.  —  Metamorphic  ;  may  be  also  altered  eruptive.  Like  granite  in  constituents, 
but  with  the  mica  and  other  ingredients  more  or  less  distinctly  in  layers,  gneiss  and 
granite  being  closely  related  rocks.  Gneiss  breaks  most  readily  in  the  direction  of  the 
mica  layers,  and  thus  affords  slabs,  or  is  schistose  in  structure. 

Varieties.  —  Most  of  them  are  similar  to  those  under  granite.  a.  Granitoid. 
b.  Strongly  schistose  and  micaceous,  c.  Muscovite  gneiss;  not  common,  d.  Muscovite- 
biotite  gneiss,  e.  Biotite  gneiss,  f.  Albitic.  g.  Oligoclase-bearing.  h.  Hornblendic. 
i.  Epidotic.  j.  Garnetiferous.  k.  Andalusitic,  or  containing  andalusite  in  disseminated 
crystals.  1.  Cyanitic  ;  contains  cyanite.  m.  Fibrolitic.  n.  Quartzose  ;  the  quartz  largely 
in  excess,  o.  Quartzytic;  consists  largely  of  quartz  in  grains,  and  intermediate  between 
quartzyte  and  gneiss,  p.  Porphyritic.  q.  Spherophyric.  r.  Quartzophyric;  containing 
quartz  in  defined  crystals  in  a  fine-grained  base. 

Some  gneiss  is  very  little  schistose,  being  in  thick,  heavy  beds,  granite-like,  while 
other  kinds,  especially  those  containing  much  mica,  are  thin-bedded,  and  very  schistose ; 
the  latter  graduate  into  mica  schist. 

GREISEN  (Hyalomicte) .  —  A  micaceous  quartz- rock,  at  Zinnwald,  where  it  sometimes 
contains  tin  ore. 

PROTOGINE,  PROTOGINE  GNEISS.  —  Granite  or  gneiss-like,  but  containing  some  hydro- 
mica,  or  chlorite,  or  both. 

MINETTE,  ORTHOLYTE. — A  fine-grained  rock  consisting  of  mica  and  orthoclase  with- 
out quartz  (mica-syenyte} .  The  Vosges,  France. 

MICA  SCHIST.  —  Metamorphic.  Mica,  with  usually  much  quartz,  some  feldspar.  On 
account  of  the  mica  usually  thin  schistose.  Either  or  both  muscovite  and  biotite  present, 
and  the  latter  (black  mica)  commonly  much  the  most  abundant.  Colors  silvery  to  black, 
according  to  the  mica  present.  Often  crumbles  easily,  and  roadsides  sometimes  spangled 
with  the  scales. 

Varieties.  —  a.  Ordinary.  b.  Gneissoid ;  between  mica  schist  and  gneiss,  and 
containing  much  feldspar,  the  two  rocks  shading  into  one  another,  c.  Hornblendic. 
d.  Garnetiferous.  e.  Staurolitic.  f.  Cyanitic.  g.  Andalusitic.  h.  Fibrolitic;  containing 
fibrolite.  i.  Tourmalinic.  j.  Ottrelitic.  k.  Calcareous,  limestone  occurring  in  it  in  occa- 
sional beds  or  masses.  1.  Graphitic  or  Plumbaginous;  the  graphite  being  either  in  scales, 
or  impregnating  generally  the  schist,  m.  Quartzose  ;  contains  much  quartz,  n.  Quartzytic  ; 
a  quartzyte  with  more  or  less  mica,  rendering  it  schistose,  o.  Specular,  or  Itabyryte  ;  con- 
taining much  hematite  or  specular  iron  in  bright  metallic  lamellae  or  scales. 


84  STRUCTURAL   GEOLOGY. 

HYDROMICA  SCHIST  OR  SLATE.  —  Metamorphic.  Thin  schistose,  consisting  either 
chiefly  of  hydrous  mica,  or  of  this  mica  with  more  or  less  quartz  ;  having  the  surface 
nearly  smooth  ;  feeling  greasy  to  the  fingers ;  pearly  to  faintly  glistening  in  luster ; 
whitish,  grayish,  pale  greenish  in  color,  and  also  of  darker  shades.  This  rock  used  to  be 
called  talcose  slate,  but,  as  first  shown  by  C.  Dewey,  it  contains  no  talc.  It  includes 
parophite  schist,  damourite  slate,  and  sericite  slate  (glanz-schiefer,  sericit-schiefer,  and 
part  of  the  glimmer-schiefer  of  the  Germans). 

Varieties. — a.  Ordinary;  more  or  less  silvery  in  luster,  b.  Chloritic ;  contains 
chlorite,  or  is  mixed  with  chlorite  slate,  and  has  therefore  spots  of  olive-green  color; 
graduates  into  chlorite  slate,  c.  Garnetiferous.  d.  Pyritiferous ;  contains  pyrite  in  dissemi- 
nated grains  or  crystals,  e.  Magnetitic  ;  contains  disseminated  magnetite,  f .  Quartzytic  ; 
consists  largely  of  quartzyte,  or  is  a  quartzyte  rendered  schistose  and  partly  pearly  by  the 
presence  of  a  hydrous  mica.  Includes  the  argillyte  or  clay-slate  which  has  the  composi- 
tion nearly  of  a  hydrous  mica,  like  that  of  the  White  Mountain  Notch,  where  much 
of  it  is  andalusitic. 

AGALMATOLYTB  (Gieseckite,  Finite').  —  Compact;  cut  with  a  knife  ;  composition  that 
of  the  hydrous  mica,  damourite.  Derived  mostly  from  the  alteration  of  nephelite.  — 
From  the  Archaean  of  Lewis  County,  N.  Y.  (Dysintryby te) ,  China,  etc. 

PARAGONITE  SCHIST.  —  Metamorphic.  Consists  largely  of  the  hydrous  soda  mica 
called  paragonite  ;  but  in  other  characters  resembles  hydromica  slate. 

FELSYTE  (Euryte,  Porphyry,  Petrosilex). —  Eruptive  and  metamorphic.  Compact 
orthoclase  with  often  some  quartz  intimately  mixed,  flint-like  in  fracture.  Opaque. 
Colors  grayish  white  to  red  and  brownish  red.  G  =  2 -56-2 '7. 

Varieties. — a.  Non-porphyritic ;  of  various  colors,  b.  Black;  rare.  c.  Porphyritic 
Felsyte,  or  Porphyry,  Orthophyric ;  containing  the  feldspar  in  small  crystals  distributed 
through  the  compact  base  ;  color  red,  and  of  other  shades,  d.  Quartzophyric  ;  containing 
quartz  in  grains  ;  often  called  Quartz-porphyry,  e.  Quartzless.  f.  Spherophyric,  the 
Pt/romeride  of  Corsica. 

PORCELANYTE  OR  PORCELAIN  JASPER.  —  Metamorphic.  Baked  clay,  having  the 
fracture  of  flint,  and  a  gray  to  red  color :  it  is  somewhat  fusible  before  the  blowpipe,  and 
thus  differs  from  jasper.  Formed  by  the  baking  of  clay-beds,  when  they  consist  largely 
of  feldspar.  Such  clay-beds  are  sometimes  baked  to  a  distance  of  thirty  or  forty  rods 
from  a  trap  dike,  and  over  large  surfaces,  by  burning  coal-beds. 

MICA-TRACHYTE.  —  Eruptive.  Consisting  of  orthoclase  and  black  mica,  with  some 
orthoclase  augite,  chrysolite,  and  glass.  Dark  grayish  green.  Mount  Catini. 

TRACHYTE  (Sanidin-trachyte) . — Eruptive.  Ash-gray,  brownish,  bluish,  rarely  red- 
dish. G  =  2-6-2  -7.  Consists  mainly  of  orthoclase,  often  with  disseminated  crystals  of 
the  glassy  tabular  variety  called  sanidin.  Named  from  the  Greek  for  rough,  in  allusion 
to  the  rough  surface  of  fracture.  Differs  from  felsyte  in  containing  some  glass,  and  a 
rougher  surface.  Graduates  into  the  following. 

RHYOLYTE,  QUARTZ-TRACHYTE.  —  Eruptive.  Like  the  preceding  in  colors,  but  con- 
taining quartz,  and  sometimes  passing  into  a  coarsely  crystallized  variety  called  Nevadyte 
(from  Nevada).  Common  in  the  Rocky  Mountain  region  and  west  of  it.  Pearly  te  and 
Lithoidyte  are  more  or  less  glassy  varieties  —  between  glass  and  stone  ;  and  pitchstone  is 
another  similar  variety,  pitch-like  in  luster.  These  graduate  into  the  following. 

OBSIDIAN  (Volcanic  glass). — Eruptive.  A  true  volcanic  glass,  but  more  or  less 
microlitic.  Colors  grayish  black,  gray,  purplish  to  red,  brown.  Sometimes  orthophyric  ; 
often  contains  spherulites,  which  are  70-75  per  cent  silica.  Pumice  is  a  scoriaceous 
variety  with  linear  cells.  Constitutes  a  high  bluff  in  the  northwest  part  of  the  Yellowstone 
Park,  north  of  Beaver  Lake,  which  has  a  top  of  pumice,  and  also  a  large  area  east  of  the 
bluff  ;  cavities  in  Obsidian  bluff  often  lined  with  crystals  of  sanidin,  tridymite,  quartz,  and 
sometimes  of  fayalite. 


KOCKS  :    THEIR   CONSTITUENTS   AND   KINDS.  85 


2.   Potash-feldspar  and  Hornblende  or  Pyroxene  Series. 

SYENYTE  (Syenite  of  Werner).  — Eruptive,  metamorphic  ;  granite-like,  coarse  to  fine. 
Gray  to  flesh-red  and  dark  gray.  Consists  of  orthoclase,  with  often  microcline  and 
hornblende  and  little  or  no  quartz  ;  biotite  and  oligoclase  often  present.  G  =  2-7-2-9. 
From  Plauen-Grund,  Saxony,  etc.  Nearly  all  American  syenyte  is  quartz-syenyte. 

QUARTZ-SYENYTE  (syenite  of  most  early  geologists,  hornblende-granite,  syenite-granite). 
—  Eruptive  and  metamorphic.  Like  syeuyte,  but  containing  quartz.  Silica  70  to  80  per 
cent.  The  name  syenite  is  from  Syene  in  Egypt,  where  a  red  granite  graduating  into 
quartz-syenyte  occurs,  and  is  the  material  used  by  the  ancient  Egyptians  for  the  exterior 
lining  of  obelisks,  etc. 

SYENYTE-GNEISS.  —  Metamorphic,  eruptive.  Like  gneiss  in  aspect  and  schistose  struc- 
ture, and  also  in  constitution,  except  that  hornblende  replaces  mica.  Common  in  Archaean 
regions,  as  the  New  Jersey  Highlands,  the  Adirondacks,  etc.  Graduates  into  Hornblende- 
schist,  a  schistose  rock  consisting  chiefly  of  hornblende. 

AUGITE-SYENYTE.  —  Eruptive.  Like  syenyte,  but  containing,  with  the  orthoclase, 
pyroxene  in  place  of  hornblende.  A  kind  free  from  quartz  occurs  at  Jackson,  N.H. ;  in 
southern  Norway.  Monzonyte  is  stated  to  be  a  variety  of  augite-syenyte. 

AUGITE-QUARTZ-SYENYTE  (Augite-granite).  —  Metamorphic;  igneous.  Like  the  pre- 
ceding, but  containing  quartz  ;  the  augite  in  part  altered  to  hornblende,  and  thence  in  all 
stages  of  gradation  down  to  a  hornblende-syenyte.  The  gneissic  variety  is  common  in 
Wisconsin,  much  more  so  than  the  granitoid. 

UNAKYTE.  —  A  flesh-colored,  granitoid  rock  consisting  of  orthoclase,  quartz,  and  epi- 
dote.  From  the  Unaka  Mountains,  Madison  County,  N.C.,  and  Cooke  County,  E.  Tenn. 

3.    Potash-feldspar  and  Nephelite  Rocks,  Horriblendic  or  not. 

ZIRCON-SYENYTE.  —  Like  syenyte.  A  crystalline  granular  rock  consisting  of  ortho- 
clase, microcline,  elaeolite,  little  hornblende,  crystals  of  zircon ;  often  also  sodalite,  segyrite,, 
eudialyte,  etc.  From  Norway  ;  Marblehead  Peninsula,  Mass.,  containing  sodalite. 

FOYAYTE.  —  Eruptive.  Coarse,  crystalline  granular  to  aphanitic.  Consists  of  ortho- 
clase, nephelite,  hornblende,  or  segyrite,  with  often  sodalite,  etc.  From  Mounts  Foya  and 
Picota  in  Portugal,  making  a  dike ;  on  eastern  slope  of  Blue  Mountain,  New  Jersey,, 
between  Beemersville  and  Libertyville. 

MIASCYTE.  —  Granitoid  to  schistose.  Consists  of  microcline,  elseolite,  biotite,  with 
some  quartz ;  often  also  zircon,  monazite,  sodalite,  cancrinite,  etc.  From  Miask,  Ilmen 
Mountains  ;  Pic  Island,  Lake  Superior ;  Litchfield,  Maine. 

DITROYTE.  —  Coarse  to  fine-grained.  Consists  of  microcline,  nephelite  (elseolite), 
and  sodalite.  From  Ditro,  Transylvania. 

PHONOLYTE  (Clinkstone}.  —  Eruptive.  Compact,  more  or  less  slaty  in  structure. 
Gray,  grayish  blue,  brownish.  Usually  clinking  under  the  hammer  like  metal  when  struck 
(and  thence  the  name).  G  =  2-4-2-7.  Consists  of  glassy  orthoclase,  with  nephelite  and 
some  hornblende.  In  Colorado,  Auvergne,  Breisgau,  Bohemia. 

4.    Leucite  Rocks,  with  or  without  Augite. 

Usually  some  sanidin  (orthoclase)  is  present,  and  often  also  nephelite  and  labradorite. 

AMPHIGENYTE  (Leudtophyre) .  — Eruptive.  Contains  augite,  like  doleryte,  but  leucite 
(called  sometimes  amphigene)  replaces  the  feldspar.  Often  contains  chrysolite,  nephelite, 
sanidin,  labradorite,  brown  mica,  with  sodalite,  etc.  Dark  gray,  fine-grained,  and  more 
or  less  cellular  to  scoriaceous.  G  2-5-2-9.  The  leucite  is  disseminated  in  grains  or  in 
24-faced  crystals.  Constitutes  the  lavas  of  Vesuvius  and  some  other  regions. 

LEUCOTEPHRYTE.  —  Eruptive.  Like  the  above,  and  occurring  in  the  same  regions, 
but  containing  much  labradorite. 


86  STRUCTURAL  GEOLOGY. 

LEUCITTTE.  —  Eruptive.  Consists  chiefly  of  leucite,  with  a  very  little  augite  and 
some  biotite.  Color,  greenish  gray.  From  Point  of  Kocks,  Wyoming. 

5.   Soda-lime-feldspar  and  Mica  Rocks. 

KEKSANTYTE  (Mica-dioryte,  Mica-porphyry te,  Soda-granite).  —  Granite-like  to  fine- 
grained. Grayish  to  brown  and  grayish  black.  Consists  chiefly  of  oligoclase  and  biotite, 
with  usually  some  hornblende,  orthoclase,  magnetite,  apatite.  Graduates  into  dioryte. 
Occurs  granitoid  at  Stony  Point,  on  the  west  side  of  the  Hudson  River,  and  near  Crugers, 
nearly  opposite  ;  in  the  Vosges. 

6.   Soda-lime-feldspar  and  Hornblende  or  Pyroxene  Rocks. 

These  basic  rocks  vary  in  the  kind  of  feldspar  present ;  in  texture,  from  coarse 
granite-like  to  aphanitic  and  scoriaceous,  even  in  the  same  kind  of  rock ;  in  composition, 
through  alteration  of  the  pyroxene,  in  many  cases,  to  hornblende,  making  them  horn- 
blende rocks ;  and  also  in  the  alteration,  in  many  cases,  of  the  pryoxene  and  chrysolite, 
when  these  are  present,  to  serpentine.  The  dark- colored  igneous  kinds  are  conveniently 
called  trap. 

DIORYTE,  QUARTZ-DIORYTE  {Greenstone  in  part).  —  Metamorphic  and  eruptive.  Typi- 
cal dioryte,  consisting  chiefly  of  oligoclase  and  hornblende,  with  often  some  orthoclase 
and  biotite.  Colors,  gray,  dark  gray,  grayish  black,  green,  greenish  black,  and  also  red. 
Chlorite  usually  present,  and  sometimes  epidote,  in  green  varieties.  Often  contains  dis- 
seminated quartz.  No  glass  is  present.  Varies  in  texture  from  granite-like  to  aphanitic. 
In  the  coarse  granite-like  dioryte  of  Crugers  the  crystals  of  hornblende  are  sometimes  4 
inches  long.  G  =  2-66-3. 

A  compact  aphanitic  kind,  of  a  red  color,  is  the  typical  red  porphyry,  or  Rosso  antico 
( porphyry  te),  of  Egypt.  That  of  Crugers  graduates  into  kersantyte,  by  loss  of  hornblende 
and  increase  of  biotite.  Dioryte  Schist  is  a  metamorphic,  slaty  rock,  having  the  compo- 
sition essentially  of  dioryte. 

AUGITE-DIORYTE.  —  Eruptive.  Consists  of  augite  and  oligoclase  with  little  horn- 
blende. Augite  often  more  or  less  changed  to  hornblende,  making  a  hornblende-dioryte 
or  the  above-described  dioryte.  No  glass.  Colors,  dark  gray  to  greenish  black  and 
black. 

A  fine-grained  rock  between  Peekskill  and  Crugers,  on  the  Hudson,  consisting  of 
oligoclase  and  hypersthene,  is  essentially  a  hyper sthene-dioryte,  although  called  noryte.  The 
hypersthene  is  often  altered  to  hornblende,  as  ascertained  by  G.  H.  Williams.  Ophyte,  a 
fine-grained  greenish  black  rock  of  the  Pyrenees,  related  to  augite- dioryte  in  composition. 

LABRADIORYTE  (Labradorite-dioryte,  Metadiabase,  Hawes).  — Metamorphic  and  erup- 
tive. Consists  of  labradorite  (or  anorthite)  and  hornblende  with  some  chlorite  and 
magnetite.  A  fine-grained,  grayish  green  to  greenish  black  and  black  rock,  sometimes 
porphyritic.  No  glass  present.  G  =  2-8-3-1.  Occurs  west  of  New  Haven,  Conn.,  as  a 
part  of  the  metamorphic  chloritic  hydromica  schist  of  the  region,  evidently  metamorphic. 
G.  W.  Hawes  obtained  in  analyses  (1876)  :  Silica  48-20,  alumina  14-12,  iron  sesquioxide 
2,  iron  protoxide  7.41,  manganese  protoxide  1-24,  lime  11-50,  magnesia  8-19,  soda  2-60, 
potash  0-23,  titanic  acid  1-58,  water  2-20  =  99-27.  In  the  Urals. 

ANDESYTE  (Hornblende-andesyte}.  —  Eruptive.  Consists  of  oligoclase  or  andesyte 
and  hornblende,  with  often  some  orthoclase  and  biotite.  Dark  or  light  green  to  gray, 
sometimes  purplish.  Has  the  aspect  mostly  of  trachyte,  but  varies  from  granitoid  to 
scoriaceous  and  glassy,  even  in  the  same  eruptive  mass,  at  Washoe,  as  ascertained  by 
Hague  and  Iddings. 

DACYTE  (Quartz-andesyte).  —Eruptive.  Like  the  above,  but  contains  disseminated 
quartz,  and  often  much  of  it.  Graduates  into  the  orthoclase  rock,  quartz-trachyte  or 


KOCKS  :    THEIE   CONSTITUENTS   AND   KINDS.  87 

rhyolyte.  From  Eureka,  Nev. ,  and  other  parts  of  the  Rocky  Mountain  region ;  also  from 
the  Andes  of  Cotopaxi,  Chimborazo,  etc. 

Propylyte  is  altered  andesyte. 

AUGITE-ANDESYTE.  —  Eruptive.  Like  andesyte,  but  containing  augite  in  place  of 
hornblende,  or  in  part  hypersthenic  ;  augite  or  hypersthene  often  altered  to  hornblende, 
often  chrysolitic.  Texture,  crystalline -granular  to  aphanitic  and  fluidal  and  glassy. 
Reported  from  the  Great  Basin.  A  chrysolitic  variety  is  one  of  the  rocks  that  have  been 
called  melaphyre. 

HYPERSTHENE-ANDESYTE.  —  Eruptive.  Like  the  preceding,  but  containing  hyper- 
sthene in  place  of  augite  or  hornblende.  Buffalo  Peaks,  Col. ;  Mount  Shasta,  etc. 

HYPERYTE  (Noryte  in  part,  Hypersthene-gabbro).  —Consists  chiefly  of  labradorite 
or  anorthite  and  hypersthene,  with  usually  some  pyroxene,  biotite,  and  magnetite,  and 
sometimes  chrysolitic.  Occurs  west  and  northwest  of  Baltimore,  Md. ;  in  the  Hartz, 
Norway,  etc. 

GABBRO. — Eruptive,  metamorphic,  granitoid.  Consisting,  like  the  following,  chiefly 
of  labradorite  and  pyroxene,  the  latter  often  a  foliaceous  (diallagic)  variety  ;  some  horn- 
blende often  present,  also  magnetite  and  ilmenite  ;  sometimes  chrysolite,  which  is  often 
changed  to  serpentine.  Color,  dull  grayish,  flesh-red  to  brownish  and  gray.  G  =  2-7-3-1, 
least  when  the  proportion  of  pyroxene  is  small.  Quartz-gabbro,  containing  disseminated 
quartz,  occurs  in  northeastern  Maryland  and  northern  Delaware. 

The  name  gabbro  is  of  Italian  origin ;  but  it  is  used  in  Italy,  as  it  has  long  been,  for  a 
green  serpentine  rock.  And  gabbro-rosso  is  a  red  altered  variety  of  the  same. 

DOLERYTE  (Trap}. — Eruptive.  Texture  varying  from  granitoid  to  aphanitic  and 
glassy,  scoriaceous  and  volcanic.  Consists  of  labradorite  and  pyroxene,  the  latter  some- 
times foliaceous.  A  kind  found  at  Lassens  Peak  contains  much  quartz  in  disseminated 
grains,  and  is  a  quartz-doleryte  (Diller).  G  =  2-8-3-1.  Color,  dark  gray  to  grayish  black, 
greenish  black,  and  brownish  to  black.  Structure  frequently  columnar,  often  chrysolitic. 
Chrysolitic  kind  sometimes  altered  to  impure  serpentine.  Ordinary  trap  often  altered 
to  a  hydrous,  chloritic  trap,  often  also  amygdaloidal,  with  feeble  luster  and  of  easy 
decomposition.  Includes  three  sections :  (1)  Diabase,  containing  no  glass  in  the  base 
and  no  chrysolite.  (2)  Doleryte,  containing  glass  in  the  base,  but  no  chrysolite. 
(3)  Basalt ,  containing  usually  more  or  less  glass,  also  chrysolite. 

The  trap  of  the  Palisades,  Connecticut  River,  and  other  parts  of  the  Triassic  of 
eastern  North  America  belongs  here,  and  much  of  that  of  the  copper  region  of  Lake 
Superior.  There  is  a  fine  exhibition  of  columnar  trap  at  Orange,  N.  J.  (Fig.  221,  page  262). 
The  name  melaphyre  has  sometimes  been  used  for  chloritic  trap.  Diabase-schist  is  a  slaty 
form  of  diabase,  probably  metamorphic. 

TACHYLYTE.  —  Eruptive.     A  black  basalt-glass,  found  in  connection  with  basalt  lavas. 

CAMPTONYTE. — Rock  resembling  diabase  and  doleryte.  Consisting  of  hornblende 
(as  an  original  mineral  of  the  rock)  and  probably  anorthite,  the  analysis  affording  only 
41  to  44  per  cent  of  silica  (Hawes,  1876  ;  Kemp,  1889).  From  Campton  Falls,  N.H.,  and 
near  Whitehall,  N.Y. 

EUCRYTE.  — Eruptive.  A  doleryte-like  rock,  consisting  chiefly  of  anorthite  and  augite, 
with  sometimes  chrysolite.  Granitoid  to  aphanitic,  and  as  a  lava.  Elfdalen,  Norway ; 
Puy  de  Dome,  France  ;  etc. 

CORSYTE  (Orbicular  Dioryte). —  Eruptive.  Consists  of  anorthite  and  hornblende, 
with  some  quartz  and  biotite.  Contains  large  concretions  consisting  of  anorthite  and 
hornblende,  with  some  quartz.  Corsica  ;  the  Shetlands,  etc. 

ANORTHITYTE  (Anorthite  Eock  of  Irving) .— Eruptive.  Crystalline  granular.  Con- 
sists largely  of  anorthite,  or  a  feldspar  near  it  in  composition,  and  is  of  a  light  gray  color 
to  white  or  faintly  greenish.  North  shore  of  Lake  Superior,  between  Split  Rock  River 
and  the  Great  Palisades,  and  in  Carltons  Peak,  near  the  mouth  of  Temperance  River. 

NEPHELINYTE    (Nepheline-doleryte,    Tephryte).  —  Neph elite   and  augite,   with  some 


88  STRUCTURAL  GEOLOGY. 

magnetite.     A  chrysolitic  variety  has  been  called  nepheline-basalt.    Ash-gray  to  dark 
gray.     Often  contains  leucite,  haiiynite,  sanidin,  etc.     At  Katzenbuckel ;  Eifel,  etc. 

TESCHENYTE. —  Consists  chiefly  of  anorthite  or  labradorite,  nephelite,  hornblende, 
and  augite.  Felsitic  in  texture.  The  hornblende  sometimes  in  large  black  prisms.  Dark 
bluish  green.  From  Teschen,  Silesia. 

III.  Saussurite  Rocks. 

EUPHOTIDE  (Gdbbro  in  part) .  —  Grayish  white  to  grayish  green  or  olive  green,  and  very 
tough.  Consists  of  saussurite,  with  diallage  or  smaragdite.  G=  2-9-3-4.  A  result  of 
the  alteration  of  a  labradorite  and  pyroxene  or  other  related  feldspar-bearing  rock,  in 
which  the  feldspar  is  changed  to  the  tough  aphanitic  mineral,  saussurite  (page  65).  Cleav- 
age of  the  feldspar  sometimes  retained,  and  found  graduating  into  this  feldspar  in  some 
cases.  Chrysolite  often  present ;  and  by  its  alteration,  serpentine  is  sometimes  abundant 
in  connection  with  it.  Occurs  near  Lake  Geneva  in  Savoy  ;  Mount  Genevre  in  Dauphin^  ; 
Corsica  in  the  Orezza  valley ;  Isle  of  Unst,  etc. 

IV.  Rocks  without  Feldspar. 
1.    Garnet,  Epidote,  and  Tourmaline  Rocks. 

GARNETYTE  (Garnet  Rock}.  —  Metamorphic.  Massive,  fine-grained.  Yellowish  or 
buff  to  greenish  white.  Tough.  G  =  3-3-3-54.  This  rock  is  the  much-used,  pale,  buff- 
colored  razor  stone  of  Viel  Salm,  in  Belgium,  the  best  of  stones  for  razors.  It  is  a  man- 
ganesian  garnet.  It  makes  layers  in  a  hydromica  (sericite)  schist.  Occurs  also  as  an 
alumina-lime  garnet  at  St.  Francois  and  Orford  in  Canada. 

ECLOGYTE  (Omphacyte).  —  Metamorphic.  Fine-grained,  granular.  Consists  of  red 
garnet  in  a  base  of  grass-green  smaragdite,  with  occasionally  zoisite,  actinolite,  and  mica. 
Very  tough.  Also  with  black  or  greenish  black  hornblende  and  some  magnetite. 

EPIDOSYTE.  —  Metamorphic.  Compact,  and  very  tough  and  hard.  Pale  green  to 
yellowish  green.  Consists  of  epidote  and  quartz.  A  pale,  yellowish  variety  from  the 
Shickshock  Mountains,  Gaspe.  H  =  7  and  G  =  3-3-09. 

TOURMALYTE  (Schorl  Rock) . —  Metamorphic.  Consists  of  tourmaline  and  quartz, 
with  often  chlorite  and  mica.  Granular  and  compact  to  schistose.  Occurs  massive  in 
Cornwall,  with  tin  ore ;  schistose  at  Eibenstock  in  Saxony ;  in  Marble  Mountains,  and 
Ragged  Ridge,  Warren  County,  N.  J. 

2.    Hornblende,  Pyroxene,  and  Chrysolite  Rocks. 

PYROXENYTE. — Eruptive.  Consists  of  black  pyroxene.  Coarse  granular,  or  fine, 
sometimes  chrysolitic.  Cortlandt,  N.Y.,  and  Stony  Point,  on  the  opposite  side  of  the 
Hudson. 

PICRYTE.  —  Eruptive.  Consists  of  chrysolite,  with  pyroxene  or  diallage  or  hyper- 
sthene.  Blackish  green,  grayish  to  brownish  red.  Often  partly  changed  to  serpentine. 
Graduates  into  chrysolitic  basalt.  From  the  Fichtelgebirge. 

LHERZOLYTE.  —  Eruptive.  Consists  of  chrysolite,  enstatite,  whitish  pyroxene,  chrome- 
spinel  (picotite),  and  sometimes  garnet.  Changed  more  or  less  to  serpentine.  From 
L.  Lherz. 

HORNBLENDYTE.  —  Eruptive  or  metamorphic-eruptive.  Consists  chiefly  of  hornblende 
(which  is  generally  altered  augite),  with  usually  chrysolite.  Massive  or  somewhat  schis- 
tose ;  coarsely  or  finely  crystalline.  Cortlandt  and  Stony  Creek,  N.Y. 

HORNBLENDE-PICRYTE.  — Usually  or  always  metamorphic-eruptive.  Consists  of  horn- 
blende (mostly  or  wholly  altered  augite)  and  chrysolite,  with  magnetite,  the  chrysolite 
changed  to  serpentine  ;  usually  more  or  less  pyroxene.  Coarse  or  fine  crystalline  granular. 
Greenish  black  and  dark  gray.  From  Anglesey  and  Carnarvonshire. 


TERRANES.  89 

DUNYTE,  PERIDOTTTE.  —  Eruptive  and  metamorphic.  Consists  almost  wholly  of 
chrysolite.  Often  changed  in  part  or  wholly  to  serpentine.  G  =  3-31.  From  Mount 
Dun,  New  Zealand  ;  Macon  County,  N.C. 

AMPHIBOLYTE.  —  Metamorphic.  Consists  chiefly  of  hornblende,  with  more  or  less 
quartz,  and  sometimes  chlorite.  Coarse  or  fine-grained  ;  hornblende  sometimes  acicular. 
Massive  or  schistose.  Graduates  often  into  chlorite  schist  and  mica  schist.  Actinolyte 
consists  chiefly  of  green  actinolite.  Bernardston,  Mass.,  and  Vernon,  Vt. 

GLAUCOPHANYTE. —  Metamorphic.  Consists  chiefly  of  the  blue  soda-bearing  horn- 
blende-like mineral  glaucophane,  with  some  black  mica ;  sometimes  epidotic.  From 
Saxony ;  Isle  of  Syra  ;  New  Caledonia  ;  California. 

V.  Hydrous  Magnesian  and  Aluminous  Rocks. 

CHLORITE  SCHIST. — Metamorphic.  Schistose.  Dark  green  to  grayish  green  and 
greenish  black.  Little  greasy  to  the  touch.  Consists  largely  of  chlorite,  with  usually 
some  quartz  and  feldspar  intimately  blended.  Often  contains  magnetite  in  crystals. 

CHLORITE-ARGILLYTE.  —  Metamorphic.  An  argillyte-like  rock  (phyllyte)  consisting 
chiefly  of  chlorite. 

TALCOSE  SCHIST.  —  Metamorphic.  Schistose.  Feels  soapy.  Consists  chiefly  of  talc. 
Not  common  except  in  local  beds,  most  of  the  so-called  "  talcose  slate  "  being  hydromica 
(sericite)  schist. 

STEATYTE  (Soapstone^).  —  Metamorphic.  Schistose  or  massive.  Consists  of  talc,  often 
with  impurities.  Gray  to  grayish  green,  white.  Easily  cut  with  a  knife. 

SERPENTINE.  —  Metamorphic.  Massive.  Aphanitic.  Easily  scratched  with  a  knife. 
Oil-green,  dark  green  to  greenish  black ;  also  of  pale  shades  to  whitish.  Feels  a  little 
greasy,  especially  the  powder.  This  metamorphic  rock  has  been  made  from  various  chrys- 
olitic,  augitic  and  hornblendic  rocks  that  were  both  of  eruptive  and  metamorphic  origin. 

OPHIOLYTE  (Verd-antique) .  —  Metamorphic.  Limestone  or  marble  colored  with  or 
containing  disseminated  serpentine  ;  clouded  or  spotted  with  green.  West  of  New  Haven, 
Conn. ;  Port  Henry,  Essex  County,  N.Y. 

PYROPHYLLYTE  SCHIST.  —  Schistose  or  massive.  Microcrystalline  or  aphanitic.  Feels 
soapy  and  looks  like  a  whitish  or  greenish  steatyte,  but  consists  of  the  hydrous  aluminous 
mineral,  pyrophyllite,  whose  atomic  or  oxygen  ratio  is  the  same  as  that  of  the  hydrous 
magnesian  mineral,  talc.  Deep  River  region,  N.C. 

II.   TERRANES:   THEIR  CONSTITUTION,   CHARACTERISTICS, 
POSITIONS,   AND   ARRANGEMENT. 

More  than  nine  tenths  of  the  rocks  of  the  earth's  surface  are  fragmental 
in  origin.  From  the  time  of  the  first  existence  of  an  ocean,  the  formation 
of  fragmental  deposits,  through  the  grinding  action  of  waves  and  currents, 
fresh-water  streams  and  winds,  aided  by  the  natural  decay  of  the  rocks, 
has  gone  forward  wherever  there  were  rocks  exposed  to  this  action.  Thus 
beds  of  sand,  gravel,  mud,  or  clay  —  that  is,  fragmental  deposits  —  have 
been  forming,  when  the  conditions  favored,  through  all  the  geological  ages. 
And  those  of  ancient  sea-borders,  rivers,  valleys,  lakes,  and  plains  are  like 
the  modern  in  all  respects,  even  to  the  frequent  ripple-marks  over  the  sur- 
face of  beds,  and  the  occasional  footprints  of  animals.  Wherever  igneous 
ejections  have  filled  the  air  with  volcanic  sand  or  ashes  for  the  winds  to 
drift  away,  this  sand  has  added  to  the  material  of  fragmental  deposits. 
Wherever  there  was  nothing  for  the  moving  waters  to  grind  up  except  shells, 


90  STRUCTURAL   GEOLOGY. 

corals,  and  other  calcareous  relics  of  living  species,  these  relics  of  the  seas 
have  been  ground  up,  as  now  in  coral  and  shell-growing  seas,  and  made  into 
limestones ;  for  limestones  are  for  the  most  part  fragmental  rocks. 

The  metamorphic  crystalline  rocks,  as  already  stated,  are  only  fragmental 
rocks  metamorphosed  or  crystallized.  The  alteration  in  some  mountain- 
making  epochs  has  changed  fragmental  formations  thousands  of  feet  in 
thickness  over  many  thousands  of  square  miles  in  area.  The  borders  of 
such  areas  are  usually  less  altered  than  the  interior  portions ;  and  hence 
in  many  places  the  transition  may  be  passed  over,  in  the  course  of  a  score 
or  two  of  miles,  from  the  simply  solidified  strata  of  the  outskirts  and  the 
faintly  crystalline  slates  and  limestone,  to  the  thoroughly  crystalline  mica 
schist,  gneiss,  and  marble ;  and  sometimes  to  granite  in  masses  or  veins  as 
an  extreme  effect. 

Chemical  deposits,  or  deposits  from  solution  in  fresh  or  salt  waters,  have 
added  sparingly  to  the  stratified  series,  and  the  outflows  of  igneous  rocks 
from  fissures  or  volcanic  rents  have  made  other  large  additions.  Part  of  such 
ejections  go  to  make  independent  conical  mountains ;  but  the  larger  part 
are  in  successive  sheets  interstratified  or  overlying  other  formations. 

Of  these  materials,  all  are  of  superficial  origin  excepting  the  igneous; 
these  are  contributions  to  the  surface  from  the  earth's  interior. 

Besides  stratified  terranes,  there  are  also  vertical  or  obliquely  placed 
sheets  of  rock  cutting  across  the  former.  They  are  the  fillings  of  opened 
cracks  or  fissures  made  across  the  terranes,  and  comprise  dikes  and  veins. 
They  have  great  geological  and  economical  importance  because  of  the  gems 
and  ores  which  veins  and  dikes  have  made  accessible  to  man,  and  because 
dikes  are  the  inferior  portions  of  great  igneous  outflows,  and  reveal  some- 
thing as  to  the  earth's  interior.  But  they  are  of  small  extent  compared  with 
the  stratified  terranes,  and  will  be  considered  under  Dynamical  Geology. 

Formations.  — From  the  explanations  that  have  been  given  it  is  apparent 
that  any  group  in  the  series  of  stratified  rocks,  whether  large  or  small,  may 
be  called  a  formation,  if  the  parts  are  related  in  period  or  time  of  origin ; 
as,  for  example,  the  Devonian  formation,  or  those  of  the  Devonian  era ;  the 
Chemung  formation,  or  those  of  the  Chemung  period  under  the  Devonian ; 
and  so  on.  The  term  is  also  used  for  a  group  of  rocks  of  similar  constitu- 
tion; as  a  calcareous  formation,  a  siliceous  formation,  etc.  The  term  terrane 
(from  the  Latin  terra,  earth,  and  the  French  terrain)  has  essentially  the 
same  signification  as  formation.  Formation  is  commonly  used  for  stratified 
terranes. 

STRATIFIED  FORMATIONS. 
1.  Structure  and  Characteristics. 

The  series  of  stratified  formations  over  the  globe  has  a  maximum  thick- 
ness of  about  30  miles.  But  the  existing  thickness  in  any  one  place  is 
seldom  even  10  miles.  Since  rocks  are  mostly  water-made,  and  for  the 
larger  part  originated  in  oceanic  waters  of  moderate  depth,  wherever  any 


TERRANES.  91 

region  has  remained  for  ages  as  permanent  dry  land,  without  interior  seas, 
little  or  no  deposits  have  been  made  over  the  surface ;  and  the  little  has 
come  through  the  winds  or  rains  or  igneous  ejections.  So,  also,  where  the 
deep  oceans  have  been  located,  the  deposits  have  been  relatively  thin.  The 
earth's  coat  of  stratified  material  is  hence  a  very  irregular  and  ragged  one. 

In  the  description  of  a  formation,  the  term  stratum  (from  the  Latin  for 
bed,  strata  in  the  plural)  is  used  for  each  section  of  the  formation  that 
consists  throughout  of  approximately  the  same  kind  of  rock-material.  Thus 
if  shale,  sandstone,  and  limestone  succeed  one  another  in  thick  masses,  each 
is  an  independent  stratum.  A  stratum  may  consist  of  an  indefinite  number 
of  beds,  and  a  bed,  of  numberless  layers.  But  the  distinction  of  layer  and 
bed  is  not  always  obvious. 

The  series  of  formations  in  the  earth's  structure  is  divided  into  series, 
groups,  sub-groups,  and  stages,  according  as  breaks  in  the  history  of  higher 
and  lower  grade  may  require.  The  series  are  the  grander  divisions ;  e.g., 
the  Devonian  series,  the  Carboniferous  series.  The  study  of  the  succession 
of  strata  or  of  beds  in  the  rocks  of  a  region,  in  order  to  ascertain  their  origi- 
nal order  and  the  characteristics  of  the  beds,  is  a  stratical  or  stratigraphical l 
investigation.  The  following  are  some  illustrations  :  — 

Fig.  59  represents  a  section  of  the  strata  as  exhibited  along  Genesee 
Eiver,  at  the  falls  near  Rochester.  The  height  of  the  section  is  400  feet. 
(1)  The  stratum  at  bottom  is  sandstone;  next  above  it  (2)  lies  a  hard,  gray 
stratum,  which  has  been  called  the  Gray 
Band.  On  this  rests  (3)  a  thick  stratum  of 
greenish  shale,  fragile  and  imperfectly  slaty ; 
and  (4)  a  compact  limestone.  Above  this 
(5)  is  another  greenish  shale,  much  like  that 
below;  then  (6)  another  great  stratum  of 
limestone;  (7)  another  thicker  stratum  of 
shale;  and,  finally  (8),  at  the  top,  is  limestone  wholly  different  from  those 
below.  The  transition  from  one  stratum  to  another  is  quite  abrupt ;  and, 
moreover,  each  may  be  traced  for  a  great  distance  through  the  adjoining 
country.  It  must  be  here  remembered  that  these  transitions  in  the  rocks 
indicate  extended  changes  in  the  conditions  of  the  rock-making  seas ;  that 
when  a  pure  limestone  was  in  progress,  the  sea  was  free  from  currents 
bringing  in  mud  or  sediment ;  when  making  shale,  the  currents  carried  in 
fine  sediment ;  when  sand,  a  coarser  sediment ;  so  that  alternations  in  depth, 
limits,  and  exposure  to  waves  and  currents,  or  not,  through  the  successive 
periods,  were  the  source  of  the  alternations  in  the  strata. 

The  succession  of  strata  in  stratified  rocks  is  exceedingly  various.  In 
other  sections,  as  at  Trenton  Falls,  K Y.,  there  are  only  limestones  in  sight ; 
but,  were  the  rocks  in  view  to  a  much  greater  depth,  sandstone  would  be 
seen.  In  still  other  regions,  there  are  alternations  of  conglomerates  and 

i  The  latter  adjective  is  a  mongrel  word,  half  Latin  and  half  Greek;  but  it  has  probably 
been  too  long  used  to  be  displaced. 


92  STRUCTURAL   GEOLOGY. 

shales ;  or  conglomerates  with  shales  and  coal-beds ;  or  conglomerates  with 
limestones  and  sandstones ;  or  shales  and  sandstones  alone. 

The  thickness  of  each  stratum  also  varies  much,  being  but  a  few  feet  in 
some  cases,  and  hundreds  of  feet  in  others;  and  the  same  stratum  may 
change  in  a  few  miles  from  100  feet  to  10,  or  disappear  altogether,  or  change 
from  one  of  shale,  or  of  limestone,  to  one  of  sandstone,  and  so  on.  In  the 
Coal-formation  of  Nova  Scotia  there  are  15,000  feet  of  stratified  beds,  con- 
sisting of  a  series  of  strata  mainly  of  sandstones,  shales,  and  conglomerates, 
with  some  beds  of  coal ;  and  in  the  Coal-formation  of  Pennsylvania  there  are 
6000  to  7000  feet  of  a  similar  character. 

In  many  cases  a  bed  of  limestone  thins  out  at  short  intervals,  and  is  thus 
in  isolated  pieces,  100  to  1000  feet,  or  more,  long,  called  lenticular  masses, 

shale   or   sandstone   occupying   the   in- 
terval.    This  results  from  the  varying 
conditions  in  the  seas  in  which  the  beds 
were  made,  some  portions  being  favor- 
able for  the  animals  that  make  shells 
and    other    calcareous    materials    from 
which  limestones  are  formed,  when  the 
larger  part  is  unfavorable.     Such  lenticular  masses  (ab,  cd,  ef,  Fig.  60)  may 
consist  of  iron-ore,  such  ores  being  often  deposited  locally  in  marshes  or 
shallow  basins,  on  sea-borders,  as  well  as  in  interior  ponds  or  shallow  lakes. 

A  seam  is  a  thin  layer  intercalated  between  layers  and  differing  from 
them  in  composition.  Thus,  there  are  seams  of  coal,  of  quartz,  of  iron-ore. 
Seams  become  beds,  or  are  so  called,  when  they  are  of  considerable  thick- 
ness ;  as,  for  example,  coal-beds.  Such  seams  are  sometimes  popularly,  but 
wrongly,  called  veins. 

The  beds  or  layers  of  rock  may  be  (1)  massive,  that  is,  of  great  thickness 
without  division  into  subordinate  layers ;  or  (2)  thick-bedded,  or  (3)  thin- 
bedded,  or  (4)  laminated,  or  (5)  shaly.  The  flagging-stone,  much  used  in 
Eastern  cities  of  this  country,  is  a  good  example  of  a  laminated  sandstone. 
Such  a  variety  of  sandstone  is  often  called  flags. 

(6)  Straticulate  structure  is  one  made  up  of  very  thin  and  even  layers, 
separable  or  not,  as  a  bed  of  slate,  a  bed  of  clay  in  a  river-valley,  stalagmite, 
and  agate.  It  is  often  called  a  banded  structure. 

(7)  Slaty  structure  is  much  like  shaly,  and  frequently  a  shale  is  called  a 
slate.     But  the  shale  is  straticulated  parallel  to  the  planes  of  deposition,  and 
the  structure  is  due  more  or  less  to  the  pressure  of  the  overlying  material ; 
while  slate   (roofing-slate)   has  much  more  even  layers,  with  a  smoother 
surface,   and    has    derived   the   slaty    structure   from   lateral  pressure,    as 
explained  beyond  (page  112). 

(8)  A  cross-bedded  structure  characterizes  a  layer  when  it  is  obliquely 
laminated,  as  in  three  of  the  layers  in  Fig.   61.      Such  layers  generally 
alternate  with  horizontally  bedded  layers.     This  style  of  bedding  is  made 
by  a  strong  movement  of  a  current  over  a  sandy  bottom,  as  in  the  move- 


TEHRAN  ES. 


93 


61. 


62. 


ment  of  the  tidal  waters  out  of  an  estuary  or  of  a  stream  over  a  sand-bed. 
It  has  been  called  current-bedding.  The  water,  as  it  moves  on,  pushes  up 
some  of  the  sand  before  it,  and  then  keeps  depositing  the  sand  over  the 
front  slope  of  the  little  elevation  so  made,  pro- 
ducing on  the  slope  a  series  of  thin  layers 
pitching  at  an  angle  usually  of  20°  to  35°  in 
the  direction  of  the  flow.  During  a  time  of 
quiet  following,  as  the  ebb  of  the  tide,  slower 
deposition  may  make  a  layer  that  is  horizon- 
tal in  bedding;  and  thus  the  cross-bedded 
layer  is  often  made  to  alternate  with  the 
horizontal. 

(9)  In  the  flow-and-plunge  structure  the  cross-bedded  layer  is  broken  up 
into  curving  wave-like  parts,  as  shown  in  Fig.  62.      This  effect  is  produced 
when  there  is  a  wave-like  plunging  action  in  the  rapidly  flowing  waters  and 
a  large  supply  of  sand  or  fine  gravel  for  deposition.     One  of  the  wave-like 

parts  in  such  a  layer  is  usually  a  yard  or 
more  long  and  six  inches  to  a  foot  thick ; 
and  may  be  much  smaller,  as  well  as  very 
much  larger.  In  one  place  in  the  stratified 
drift  near  iSTew  Haven,  Conn.,  the  thickness 
was  six  to  eight  feet.  The  whole  thickness, 
in  all  cases,  was  produced  by  one  fling  of  the 
waters. 

By  studying  the  structure  of  layers,  we 

are  enabled  to  determine  the  conditions  under  which  rock-formations  were 
made ;  and  hence  the  facts  have  great  interest  to  the  geologist 

(10)  The  beach-structure  is  another  of  like  interest,  indicating  a  beach 
origin.     The  upper  part  of  a  'beach,  above  high-tide  level,  is  made  by  the 
toss  of  the  waves,  and  especially  in  storms ;  and  it  is  generally  irregularly 
bedded.     But  the  lower  part,  swept  by  the  tide,  has  usually  an  even  seaward 
slope  ;  and  the  beach  deposits  over  it  have  therefore  a  corresponding  inclina- 
tion —  usually  5°  to  8°  when  the  tides  are  low,  but  15°  to  18°  when  high. 
When  the  sands  are  coral  or  shell  sands,  they  become  cemented  into  a  calca- 
reous sand-rock,  and  show  well  the  straticulation. 

(11)  The  wind-drift  structure  is  of  very  different  character.     It  is  made 
up  of  straticulate  portions,  in  different  positions,  oblique  to  one  another,  as 
in  Fig.  63.     A  ridge  of  sand  made  by  the  drift- 
ing   winds    on    a    coast    becomes    straticulate 

parallel  to  its  upper  surface,  because  the  dep- 
osition by  the  winds  is  necessarily  over  the 
surface.  But  if  such  a  ridge  has  its  upper 
half  shaved  off  obliquely  in  a  heavy  storm, 
deposition  will  afterward  go  on  parallel  to  the  new  surface,  and  hence  at  an 
angle  with  the  earlier  layers.  By  repetitions  of  such  events  the  wind-drift 


63. 


94 


STBUCTUKAL   GEOLOGY. 


structure  is  produced.  It  characterizes  part  of  the  "Pictured  Rocks"  of 
the  south  shore  of  Lake  Superior  (Foster  and  Whitney's  Report,  from 
which  the  above  figure  was  taken),  and  shows  that  the  beds  were  not  made 
in  deep  waters,  but  above  the  sea  level  by  the  drifting  winds,  like  the  drift- 
sand  ridges  of  a  windward  coast. 

(12)  The  mud-cracks  made  over  a  drying  mud-flat  are  often  preserved  in 
the  rocks  (Figs.  64  and  65),  and  prove  the  mud-flat  origin  of  the  bed. 
Such  cracks  are  necessarily  shallow,  as  they  are  limited  by  the  depth  of  the 
mud.  The  cracks  become  filled  by  the  sediment  after  a  return  of  the  waters, 


64. 


65. 


Mud-cracks.    D.  '49. 


and  into  this  filling  a  cementing  solution  may  pass  from  above.  If  the  solu- 
tion is  siliceous,  the  filling  becomes  harder  than  the  rock  either  side,  so  that 
when  worn,  the  surface  is  one  of  prominent  intersecting  ridgelets,  as  in  the 
figures.  Moreover,  these  ridges  are  generally  double,  the  filling  having 
solidified  against  either  wall  of  the  crack  until  the  two  sides  met  at  the 
center,  and  became  more  or  less  perfectly  united.  Layers  having  such  filled- 
up  mud-cracks  are  very  common  in  stratified  rocks. 

(13)  Ripple-marks  (Fig.  66),  a  series  of  wavy  ridgelets,  precisely  like 
the  ripples  on  a  sand-beach,  are  also  common  in  many  sandstones,  the  oldest 
as  well  as  the  latest,  and  are  often  indications  of  sand-flat  origin,  —  like  the 
sand-flats  off  many  seashores  or  in  bays,  though  not  necessarily  so,  since 
ripples  may  form  over  the  bottom  as  far  down  as  oscillation  in  the  water 
extends,  which  may  be  a  hundred  yards  or  more ;  and  they  are  also  formed 
by  the  winds  over  surfaces  of  loose  sand. 

(14)  Wave-marks  are  faint  outlinings  on  a  bed  of  sandstone,  like  the 
outline  left  by  a  wave  along  the  limit  where  it  dies  out  upon  a  beach, 
marking  the  outline  of  a  very  thin  deposit  of  sand.     They  have  the  same 
kind  of  significance  as  ripple-marks,  but  are  surer  evidence  that  the  beds  are 
of  beach  origin. 


TEKEANES. 


95 


(15)  Rill-marks  (Fig.  67)  are  still  clearer  evidence  of  a  beach-made 
deposit ;  they  are  the  little  f  urrowings  made  by  the  rills  that  flow  down  a 
beach  as  the  waters  of  a.  wave  or  tide  retreat,  and  which  become  apparent 
especially  where  a  pebble  or  shell  lies,  the  rising  of  the  water  upon  the 


pebble  causing  a  little  plunge  over  it  and  a  slight  gullying  of  the  surface  for 
a  short  distance  below.  The  figure  is  from  a  slab  of  thinly  laminated  sand- 
stone of  the  Medina  formation,  New  York,  as  described  and  figured  by 
James  Hall. 

(16)  Rain-prints    or    rain-drop   impressions  are   indications,   like   mud- 
cracks,  of  exposure  above  the  water  level  at  low  tide,  or  at  least  a  low  stage 
of  the  waters,  when  the  bed  of  rock  containing  them  was  yet  loose  mud  or 
sand.     A  slab  three  by  eight  feet  in  size,  now  in  the  Yale  College  cabinet 
(from  Greenfield,  Mas*.),  is  covered  throughout  with  such  impressions;  and 
as  the  impressions  are  slightly  oblong  and  oblique,  they  bear  evidence  of  the 
direction  of  the  wind  at  the  time  of  the  short  brisk  shower.     The  slab  is 
crossed  by  a   line  of   footprints  showing  that   an   animal   of  long  stride 
(probably  a  Dinosaur)  walked  over  the  mud-flat  just  before  the  shower; 
for  there   are   rain-prints    in    the   tracks.      This    is    an    example    of    the 
geoglyphics  from  which  the  geologist  derives 

facts  for  geological  history.  Another  les- 
son, too,  comes  from  the  rain-prints,  for 
they  show  that  it  rained  millions  of  years 
since. 

(17)  Other  markings  observed  at  Green- 
field, Portland,  and  other  places  in  the  Con- 
necticut valley,  are  scratches  and  groovings 
made  apparently  by  a  floating  log,  one  end 
or  branch  of  which  dragged  in  the  mud. 

Others  found  there  and  elsewhere  are  the  trails  of  Worms,  and  tracks  of 
Insects,  Crustaceans,  Reptiles,  and  other  animals,  all  of  which  give  instruction 
in  many  ways. 


96  STRUCTURAL   GEOLOGY. 

(18)  Scratches  (striae)  or  furrows  or  polished  surfaces  sometimes  cover 
rocks,  which  have  been  produced  by  abrasion  attending  movements.     They 
often  cover  the  walls  of  fissures,  and  sometimes  the  surfaces  of  beds  of  rock ; 
and  in  such  cases  they  are  called  by  the  miners'  term,  slickensides.     They 
occur  also  over  the  rocky  surface  of  a  country  as  a  result  of  past  or  recent 
glacier  flows;  and  such  are  called  simply  glacier  scratches  or  striae.     This 
subject  is  further  explained  under  Dynamical  Geology. 

(19)  Concentric  structure.  —  In  concentric  structure  there  is  an  aggre- 
gation  of   matter   around   a   center,  making,  usually,  spheres  or  flattened 
spheroids,  as  in  Figs.  69-83.     The  form  is  usually  dependent  on  growth  by 
deposition  from  a  solution  around  a  center,  so  that  the  growth  is  outward, 
or  centrifugal.      In  ordinary  concretions  it  is  growth  by  accretion,  and  it 
sometimes  produces  a  series  of  distinct  concentric  layers.     The  forms  are 

69-80. 


spherical  (Fig.  69)  ;  more  frequently  flattened  spheroids  (Figs.  74,  83)  ;  and 
very  frequently  aggregations  of  concretions  that  are  symmetrical  in  arrange- 
ment (Figs.  79,  80).  Concentric  layers  are  shown  in  Figs.  71  and  81.  At 
the  center  there  may  be,  as  a  nucleus,  a  shell  (Fig.  70),  or  a  spider,  or  insect, 
or  leaf,  or  merely  a  grain  of  sand  undistinguishable  by  the  unaided  eye.  They 
often  form  as  the  first  step  in  the  process  of  consolidation,  and  make  a  rock 
consisting  of  concretions  which  may  disappear  when  the  consolidation  is  com- 
plete. Some  layers  may  have  spherical  concretions,  and  another  above  and 
below  flattened  (Fig.  82),  those  beds  in  which  filtrating  waters  spread  with 
equal  facility  in  all  directions  having  spherical,  and  those  of  a  laminated 
structure,  in  which  the  waters  spread  laterally  most  easily,  having  spheroidal 
or  flattened  kinds.  They  are  sometimes  hollow  rings,  or  contain  a  ball  within 
(Figs.  77,  78). 

The  kind  represented  in  Fig.  81,  in  which  the  concretions  are  about  as 
large  as  peas,  is  called  pisolite,  from  the  Latin  for  pea.  A  similar  kind, 
having  the  spheres  about  as  large  as  the  roe  of  fish,  but  not  often  with  con- 
centric layers,  is  the  rock  oolyte.  Oolyte  is  now  forming  on  the  Florida 


TERRANES. 


97 


banks,  and  is  common  among  the  old  limestones  of  the  world.  Calcareous 
concretions  are  most  common.  Those  of  pyrite,  limestone,  and  quartz 
are  also  common;  and  many  other  minerals  take  the  concretionary  form. 
Nodules  of  flint  or  chert  in  rocks  are  often  concretions,  and  frequently  have 
a  fossil  as  a  center. 


81. 


82. 


The  consolidation  of  a  concretion  is  sometimes  followed  by  further  drying 
from  the  outside  inward,  and  in  this  process  the  interior  often  becomes 
much  cracked,  as  in  Figs.  72,  73;  and  the  cracks  may  be  afterward  filled 
with  calcite  or  some  other  material,  and  make  septaria,  the  name  alluding  to 
the  division  or  septation  of  the  interior.  These  septaria  concretions  occur  at 
times  in  very  large  flattened  forms,  even  one  to  three  feet  in  diameter,  when 
they  are  sometimes  popularly  called  petrified  turtles,  from  the  resemblance 
to  the  back  of  a  turtle  in  the  divisions  ;  the  more  beautiful  kinds  are  often 
sawn  into  circular  slabs  and  polished  for  table-tops. 

Solidification  from  fusion  often  produces  concretions  in  the  mass  which 
sometimes  consist  of  more  or  less  distinct  concentric  layers  of  different 
minerals,  or,  it  may  be,  of  a  single  mineral.  Fig.  84  illustrates  this  structure 
in  a  granite-like  rock,  the  "  orbicular  dioryte  "  of  Corsica.  The  pudding- 
granite  of  Craftsbury,  Vt,  contains  large  black,  ovoidal  concretions,  consist- 
ing chiefly  of  black  mica. 

Concretions  are  also  made  by  growth  radially  from  a  center,  but  this  kind 
is  of  inferior  geological  importance.  The  process  makes  attached  spheres 
and  hemispheres,  radiately  fibrous  or  colum- 
nar within.  An  example  —  in  a  reversed 
position,  in  order  to  exhibit  the  interior 
structure  —  is  shown  in  Fig.  76. 

Spheres  and  irregular  spheroids  or  balls 
in  rocks,  when  hollow  within  and  lined 
with  crystals,  are  not  concretions,  but  in- 
stead geodes;  and  any  cavity  so  lined, 
whatever  the  shape,  takes  this  name. 
Geodes  are  often  quite  large,  as  in  the 
Keokuk  limestone  of  Iowa  and  Illinois, 
where  they  have  been  supposed  to  occupy 

the  centers  of   sponges  that  were  at  some  time  hollowed  out  by  siliceous 
solutions,  like  the  hollowed  corals  of  Florida,  and  then  lined  with  crystals 
DANA'S  MANUAL  —  7 


84. 


98 


STRUCTURAL   GEOLOGY. 


by  deposition  from  the  same  or  some  other  mineral  solution.  Geodes  are 
common  in  veins  of  ore,  and  also  occupying  the  cavities  of  amygdaloids. 

The  concentric  structure  is  produced  also  by  consolidation  progressing 
inward  from  the  exterior  —  a  centripetal  process.  Spheroidal  masses  of  sand, 
often  of  oblong-spheroidal,  as  well  as  other  shapes,  colored  deeply  with  iron 
oxide,  are  often  hard  outside,  and  have  mere  loose  sand  within ;  or  they  have 
one  or  more  concentric  layers  of  ferruginous  color  within,  or  a  series  of 
concentric  shells  of  sand,  and  sometimes  also  a  loose  ball,  as  in  Fig.  75. 

A  concentric  structure  is  produced  also  by  decomposition  along  fracture- 
planes,  when  these  divide  a  rock  into  small  portions  (as  explained  on  page 
127),  and  also  by  alternate  heating  and  cooling  (page  337). 

2.    Original  Positions  of  Strata. 

Strata  in  their  original  positions  are  commonly  horizontal,  or  nearly  so. 
The  level  plains  of  alluvium  and  the  extensive  delta  and  estuary  flats 
show  the  tendency  in  water  to  make  its  depositions  in  nearly  horizontal 
planes.  The  deposits  formed  over  soundings  along  seacoasts  are  other 
results  of  sea  action ;  and  here  the  beds  vary  but  little  from  horizontality. 
Off  the  coast  of  New  Jersey,  for  80  miles  out,  the  slope  of  the  bottom 
averages  only  1  foot  in  700,  —  which  no  eye  could  distinguish  .from  a  perfect 
level.  Over  a  considerable  part  of  New  York  and  the  States  west  and  south- 
west, and  in  many  other  regions  of  the  globe,  the  strata  are  actually  nearly 
horizontal  at  the  present  time.  In  the  Coal-formation,  the  strata  of  which 
have  a  thickness,  as  has  been  stated,  of  5000  to  15,000  feet,  there  is  direct 
proof  that  the  beds  were  horizontal  when  formed ;  for  in  many  of  the  layers 
there  are  fossil  trees  or  stumps  standing  in  the  position  of  growth,  and  some- 
times several  of  these  rising  from  the  same  layer. 
Fig.  85  represents  these  tilted  coal-beds  c,  c,  with  the 
stumps  s,  s,  s.  Since  these  trees  must  have  grown  in 
a  vertical  position,  like  all  others,  and  as  now  they 
are  actually  at  right  angles  to  the  layers,  and  parallel 
to  one  another,  they  prove  that  the  beds  originally 
were  horizontal.  The  position  of  shell  accumulations 
and  coral  reefs  in  modern  seas  shows,  further,  that 

all  limestone  strata  must  have  been  nearly  or  quite  horizontal  when  they 
were  in  the  process  of  formation. 

Variations  from  horizontality.  —  (1)  Some  variation  from  horizontality 
may  be  produced  by  the  slope  of 

the  sea-bottom  in  certain  cases ;  86- 

and  in  lakes,  off  the  mouths  of 
rivers  (Fig.  86),  quite  a  con- 
siderable inclination  may  result 
from  the  fact  that  the  succes- 
sive layers  derived  from  the  inflowing  waters  take  the  slope  of  the  bottom 
on  which  they  fall. 


85. 


TERRANES. 


99 


(2)  The  depositions  of  a  mountain  stream  where  it  abruptly  reaches  a 
plain  make  a  broad  low  cone,  stratified  parallel  to  its  surface,  called  an 
"alluvial  cone."     See  page  194,  under  Kivers.     Such  fresh-water  accumula- 
tions have  thus  far  been  found  only  among  recent  formations. 

(3)  The  deposits  of  sand  constituting  a  sea-beach,  as  stated  on  page  93, 
take  the  slope  of  the  beach,  which  may  vary  from  3°  and  less  to  18° ;  and 
they  have  distinct  bedding  parallel  to  the  sloping  surface. 

These  cases  of  an  inclined  position  are  relatively  of  limited  extent. 
They  do  not  affect  the  truth  of  the  general  proposition  that  the  original 
position  of  the  earth's  great  stratified  rocks  is  essentially  horizontal. 

(4)  Another  example  of  inclined  stratification  is  afforded  by  the  volcanic 
mountains  of  the  globe,  whose  lava-streams  usually  have  a  pitch  between 
3°  and  20°,  but  may  have  a  less  or  a  much  greater  pitch.     In  the  volcanic 
mountain  the  stratification  is  pericentric,  more  completely  so  than  in  the 
alluvial  cone. 

3.  Fractured  and  Displaced  Strata. 

Strata,  however  continuous  and  horizontal  when  first  formed,  are,  at  the 
present  time,  more  or  less  divided  up  by  planes  of  fracture,  and  sometimes 
profoundly  so.  In  general,  also,  they  have  lost  their  original  horizontality, 
and  instead  the  beds  have  a  pitch,  small  or  large,  sometimes  rising  to  verti- 
cality  or  even  beyond.  In  many  mountain  regions  the  strata  are  in  great 
flexures,  each  flexure  miles  in  sweep.  Further,  fractured  and  flexed  strata 
have  often  been  displaced  along  a  fracture,  either  upward  or  downward,  in 
some  cases  a  few  inches,  in  others  miles,  the  rocks  on  one  side  of  the  plane 
of  fracture  being  dropped  down  or  shoved  up  to  this  extent.  In  addition, 
all  regions,  especially  mountain  regions,  have  lost  a  vast  amount  of  rock 
through  the  long-continued  wear  of  flowing  waters,  which  has  reduced  flex- 
ures to  ledges  and  level  surfaces,  concealing  displacements  and  disguising 
greatly  the  original  features  of  a  region. 

The  following  are  explanations  of  terms  used  in  describing  upturned  and 
displaced  rocks :  — 

An  outcrop  is  a  projecting  ledge  of  rock  (Fig.  87). 


The  dip  is  the  angle  which  the  beds  make  with  a  horizontal  surface ;  and 
its  direction  is  down  the  sloping  surface,  in  the  direction  in  which  the  angle  is 
greatest  —  dp  in  Figs.  87  and  88.  The  inclination  of  a  sloping  bed  or  of  a  wall 


100 


STRUCTURAL   GEOLOGY. 


is  in  the  opposite  direction  from  the  dip.    The  strike  is  the  horizontal  direction, 

st  (Fig.  87),  at  right  angles  to  the  dip.  The  direction  of  strike  is  ascertained 

by  means  of  a  compass;  and 
the  angle  of  dip  by  a  clinometer. 
A  clinometer-compass  is  a  com- 
pass in  which  the  movement  of 
a  plummet  measures  the  angle 
of  dip,  the  degrees  being  marked 
on  a  graduated  arc,  as  shown  in 
Fig.  89.  The  compass  in  its  best 
form  has  a  square  base,  with  one 
side  of  the  square  parallel  to 
the  N.-S.  line,  so  that  the  side 

may  be  used  in  place  of  the  line,  or  the  instrument  may  be  applied  by  one 

side  to  the  rock,  or  used  in  sighting  distant  slopes. 

The  edges  of  outcropping  layers  give  the  true  dip  only  when  the  section  affording 
them  has  the  direction  of  the  dip,  as  those  on  the  right  side  of  Fig.  87,  or  those  of  the 
side  1  in  Fig.  88  ;  but  those  of  sides  (or  sections)  2  and  3  in  the  latter  figure  vary  in  direc- 
tion from  the  dip  ;  and  those  of  4  have  no  dip,  but  are  horizontal,  and  have  therefore  the 
direction  of  the  strike. 

In  the  best  clinometer-compass  the  square  base  is  about  3  inches  in  diameter.  A 
clinometer  (Fig.  89  B)  is  easily  made  out  of  a  block  of  hard  wood,  3  to  3|  inches  square,  and 
half  an  inch  thick.  A  small  compass  may  be  set  into  the  same  block,  with  its  N.-S.  line 
parallel  to  one  side  of  the  block,  as  in  the  figure,  making  the  instrument  serviceable  for 
taking  directions  of  strike  or  dip,  though  too  small  for  good  compass  work. 

In  making  observations,  first  take  the  strike,  and  in  recording  it  refer  it  to  the  north 
point;  e.g.  N.  20°  E.  (if  that  be  the  direction),  never  S.  20°  W.  ;  only  the  direction  of 
glacial  scratches  should  be  referred  to  the  south  point.  Next  note  whether  the  dip  is 
easterly  or  westerly,  and  measure  the  amount ;  if  50°  easterly,  then  it  is  50°  in  the  direc- 
tion S.  70°  E.,  this  course  being  at  right  angles  to  the  strike.  The  entry  "  strike  N.  20°  E., 
dip  50°  E."  includes  the  whole.  To  obtain  the  true  strike,  the  edge  of  the  laminated  rock 
selected  for  the  measurement  must  be  perfectly  horizontal ;  if  there  is  none  such  in  an 
outcrop,  draw  a  horizontal  line  on  one  of  the  beds.  The  error  from  a  variation  from 
horizontality  increases  as  the  dip  decreases,  and  becomes  null  only  when  the  dip  is 
vertical. 

In  taking  the  strike,  the  side  of  the  square  compass  parallel  to  its  N.-S.  line  should 
be  used  ;  and  it  is  better  to  apply  it  to  a  piece  of  board  laid  over  the  rock  than  to  the 
rock  itself.  But  it  is  not  necessary  to  put  it  on  the  rock ;  it  is  generally  best  to  make  the 
observation  standing,  with  the  N.-S.  side  of  the  compass  between  the  eye  and  the  out- 
cropping edge.  The  same  method  may  be  used  also  in  taking  the  dip  ;  and  if  the  observer 
is  in  the  line  of  strike,  he  can  thus  take  the  dip  even  when  the  ledge  is  rods  distant.  The 
slope  also  of  a  mountain  on  the  horizon  can  be  obtained  with  a  clinometer  in  the  same 
way. 

Before  making  a  measurement,  it  must  be  ascertained  that  the  outcrop  is  not  that  of 
a  bowlder,  or  of  layers  displaced  by  the  growing  roots  of  trees ;  and  that  the  particular 
locality  will  give  a  mean,  not  a  local,  result.  Perfectly  uniform  strikes  or  dips  for  a 
distance  of  a  hundred  yards  are  not  generally  to  be  expected,  —  a  fact  that  will  trouble  the 
young  geologist  in  his  first  field  observations. 

When,  among  the  exposed  sections  at  a  place,  none  is  at  right  angles  to  the  strike, 


TEEEANES. 


101 


the  dip  may  be  obtained  thus:  take  the  dip  and  the  direction  along  two  of  the  sections; 
then,  from  a  point,  A,  draw  two  straight  lines,  AB,  AC,  in  the  directions  of  the  observed 
dips,  and  set  off,  on  each,  lengths  proportional  to  the  cotangent  of  its  own  dip,  A6,  Ac  ; 
then,  a  line  through  &,  c  will  have  the  direction  of  the  strike,  and  a  perpendicular  to  it, 
that  of  the  dip. 

In  studying  a  region  of  rocks  it  is  important  that  the  dip  and  strike  should  be  obtained 
at  all  outcrops,  and  noted  down  on  a  map.  For  the  latter,  the  best  mode  is  to  use  a 
symbol  like  the  letter  T,  giving  the  top  the  direction  of  the  strike  and  the  stem  that  of 
the  dip  ;  and  the  different  angles  of  dip  may  be  approximately  indicated  by  variations  in 


90. 


i  m 


90°     80°      70°      60°      50°     45°      35°      25° 


15° 


the  length  of  the  stem  of  the  T,  as  in  the  annexed  figure,  in  which  the  ratio  of  the  stem 
to  half  the  top  of  the  T  is  for  80°  =  1  :  4  ;  for  70°,  1:3;  for  60°,  1:2;  for  50°,  1 :  1± ;  for 
45°,  1:1;  for  35°,  1£ :  1 ;  for  25°,  1| :  1 ;  for  15°,  2:1;  and  for  horizontality,  a  crossed 
circle. 

Flexures.  —  Some  of  the  forms  of  flexures  are  illustrated  in  the  following 
figures.  Such  flexures,  while  often  very  small,  may  be  several  thousands 
of  feet  in  height,  and  many  are  miles  in  span.  The  following  are  a  few  of 
the  forms.  The  slopes  either  side  of  the  center  are  seldom  equal.  In 
4,  Fig.  91,  Aa  is  the  axis  of  the  flexure,  and  in  both  of  those  to  the  right 

91. 


this  axis  of  symmetry  is  inclined ;  and  in  5  and  6,  still  more  inclined ; 
while  in  7,  8  (from  the  Alps)  other  complexities  are  represented.  Flexures 
like  those  in  the  right  half  of  5  and  in  6  are  called  overthrust  flexures, 
the  flexing  being  due  to  pressure  from  the  right.  Supposing  the  pressure 


102 


STBUCTURAL   GEOLOGY. 


tb'have  come  from  the  left,  they  would  be  underthrust  flexures,  —  a  kind 
that  is  exemplified  in  some  sections  of  the  Alps,  but  is  not  common  like  the 
overthrust. 

Flexures  are  either  anticlines  or  synclines.  Upward  and  downward  bends 
alternate,  as  the  figures  show;  the  upward,  lettered  A,  are  anticlines, — 
so-named  from  the  Greek  aVrt,  opposite,  and  K\LVO),  incline;  and  the  down- 
ward, are  synclines  —  from  ow,  together,  and  KXtvw.  When  strata  have  been 
pushed  up  so  as  to  dip  only  in  one  direction,  the  structure  is  called  mono- 
clinal,  from  /xm/os,  one,  and  /cA<W  One  example  of  a  monocline  is  shown  in 
Fig.  91  (2) .  The  beds  in  Fig.  96,  on  page  104,  have  a  monoclinal  position, 
but  they  may  be  either  those  of  a  monocline  or  of  anticlines  and  synclines, 
as  explained  beyond. 

As  the  following  figures  of  actual  sections  indicate,  flexures  are  not 
found  in  nature  with  their  original  forms,  owing  to  the  wear  such  regions 
have  always  undergone.  Fig.  92,  by  Rogers,  represents  a  section  six  miles 

92. 


v  vi  Y 
Appalachian  section,  Virginia.     Rogers,  '42. 

long,  from  the  Appalachians  in  Virginia.  The  strata  are  numbered,  so  that 
the  flexures  of  a  given  stratum  may  be  followed ;  thus  III  bends  over  II, 
to  the  left  of  the  middle  of  the  figure,  and  the  right  portion  descends  to 
come  up  again  in  III  at  the  right  end  of  the  figure ;  again,  IV,  to  the  left, 
rises  and  bends  over  III  and  II,  though  disjoined  about  the  top  of  the  fold 
by  Denudation. 

Fig.  93  represents  a  section  from  the  Swiss  side  of  the  central  Alps. 
To  the  right,  the  strata,  1  to  6,  are  so  flexed  over  that  the  newest  stratum  6  is 
beneath  4,  3,  2,  1,  with  1,  the  oldest,  at  top.  The  dotted  lines  help  in 
tracing  out  the  flexures.  Other  sections  from  the  Appalachians,  the 
Alps,  and  other  regions,  are  given  under  the  subject  of  Mountain-making 
(pages  355-360). 

93. 


Section  east  of  Lucerne,  extending  south,  15  m.,  through  Windgalle  (4,  to  the  right),  a  peak  10,455  feet 
high  ;  1,  Gneiss;  2,  Triassic  beds;  3,  Lias;  4,  Jurassic,  above  the  Lias;  5,  Cretaceous;  6,  Eocene 
Tertiary,  including  Nummulitic  beds.  Heim. 

Besides  the  apparent  irregularities  introduced  into  a  region  of  flexures 
by  denudation,  there  are  others  still  greater  arising  from  fractures  and 
faults  (displacements).  Overthrust  flexures  very  commonly  become  broken 


TERKANES. 


103 


94. 


and  faulted  in  the  direction  of  the  thrust,  and  the  beds  become  stretched 
and  thinned  in  the  process,  as  explained  beyond. 

In  Fig.  94,  which  represents  a  surface  only  six  feet  square,  the  synclines 
and  anticlines  are  a  few  feet  only  in  span ;  moreover,  as  is  seen,  the  little 
anticlines  have  still  smaller  anticlines  and 
synclines  subordinate  to  them ;  so  that  the 
figure  represents  compound  flexures.  But 
these  small  flexures  at  the  locality  are 
subordinate  to  the  great  flexures  of  the 
region,  which  are  thousands  of  feet  in 
span,  so  that  they  are  portions  of  a 
doubly-compound  system  of  flexures. 

Since  flexures  are  greatly  disguised,  as 
explained  above,  so  that  the  kind  is  seldom 
indicated  in  the  exterior  form,  their  nature 

has  to  be  learned  from  the  dip  and  other  characters  of  the  associated  beds. 
A  portion  of  a  flexure  may  be  mistaken  for  a  monocline  unless  the  region  is 
well  studied. 

Fig.  95  represents  the  rocks  with  their  true  dip  along  4  parallel  sections  across  a 
country,  the  blocked  areas  being  limestone  and  the  others  mica  schist.  They  show 
what  may  be  the  actual  appearance  of  a  region  of  folded  rocks  after  it  is  worn  down 
to  a  nearly  level  surface.  All  that  is  visible  over  the  region  is  the  upper  surface  and 
enough  below  it  to  give  the  true  dip ;  and  from  these  facts  and  the  study  of  the  characters 


95. 
A\\ 


'i  sch: 


[E.Sch. 


/  f/E.Sch. 


.        .     .....       ............ 


*8ch. 


— ^m 

\s\  \ ''']'--.';••  r. .'-'-" ^--"'..'"'X  / /""'.*"*-." *••.! x""""""'.^..— -*".-*"*/  •' 

Flexures  in  limestone  and  schist,  Westchester  Co.,  N.Y.    D.  '81. 

of  the  beds  throughout  the  region,  the  kinds  of  flexures  are  deduced.  The  dotted  lines 
show  one  interpretation  of  the  facts.  The  synclinal  near  the  middle  of  section  1  is  over- 
laid by  schist  in  2,  and  by  still  more  schist  in  3  and  4  ;  and  changes  occur  also  in  the  other 
flexures.  But  other  interpretations  are  possible. 


104 


STRUCTURAL   GEOLOGY. 


Fig.  96  below  represents  a  section  of  alternating  belts  of  limestone  and  schist,  numbered 
I  to  IIIII,  to  be  interpreted. 

It  may  be  that  each  belt,  I,  II,  III,  IIII,  IIIII,  is  an  independent  stratum,  alike  in 
dip,  with  IIIII  the  highest  in  the  series.  This  is  the  simplest  explanation.  But  there 
may  be  flexures,  and  Figs.  97,  98,  99  represent  some  of  the  possible  methods  of  interpre- 
tation. By  comparing  each  with  Fig.  96,  the  relations  may  be  studied  out. 


97. 


In  a  region  of  flexed  rocks  the  same  bed,  as  the  illustrations  show,  may  come  many 
times  to  the  surface  ;  and  it  is  therefore  easy  for  the  observer  to  be  deceived  in  such 
regions  as  to  the  number  of  independent  beds.  The  covering  of  soil  adds  greatly  to  the 
difficulty,  as  the  following  figures  illustrate.  When  the  rock  in  a  region  of  high  dips  is 

100. 


101. 


102. 


simply  a  slate  or  shale,  with  no  associated  stratum  of  permanent  horizon,  it  is  almost 
impossible  to  decide  as  to  flexures.  Such  beds  bend  easily,  and  may  be  full  of  flexures, 
and  yet  none  may  be  apparent. 

Sometimes  an  anticlinal  flexure  has  the  dips  of  a  synclinal,  as  in  the  central  part  of 
Fig.  102  A.     If  worn  down  to  a  plane  (Fig.  102  B),  the  dips  along  the  center  would  seem 

to  be  good  evidence  of  a  syncline.  Such  fan-shaped  folds 
are  common  on  a  small  scale  in  schists,  and  occasionally 
they  may  occur  on  a  scale  of  mountain  magnitude.  The 
facts  at  Mont  Blanc  in  the  Alps  are  explained  on  the  idea 
of  such  a  fold. 

To  reach  positive  conclusions  among  the  possible 
explanations,  the  beds  or  strata  must  be  carefully  com- 
pared, and  also  the  sides  and  middle  of  the  several  strata, 
as  to  texture  and  all  other  differences.  Besides,  search 
should  be  made  for  outcrops  that  exhibit  the  limestone 
and  schist  in  broad  anticlinals  or  synclinals,  as  in  the 

following  cases.  In  Mount  Washington  and  Greylock  of  the  Taconic  range  on  the  boun- 
dary of  western  New  England,  the  beds  dip  at  the  north  end  of  the  mountain  mass,  nearly 


TERRANES. 


105 


as  in  Fig.  103  ;  that  is,  the  dip  is  alike  eastward  on  the  east  and  west  sides  of  the  range, 
and  it  is  not  clear  whether  the  overthrust  flexure  is  anticlinal  or  synclinal.  But  toward 
the  other  end,  the  dips  of  the  east  side  change,  through  the  positions  in  C  and  B  to 
that  in  A  ;  and  here  they  are  plainly  in  opposite  directions  on  the  two  sides,  and  indicate 
thus  that  the  mountain  is  a  synclinal  flexure,  basin-like  at  one  end,  and  a  careened  trough 
at  the  other. 

Flexures  have  ordinarily,  if  not  always,  the  ridge-line  inclined  instead  of 
horizontal.  The  making  of  horizontal  flexures  (that  is,  those  with  the  ridge 
line  horizontal)  would  require  perfectly  equable  pressure  along  a  region,  and 
also  perfectly  equable  resistance,  neither  of  which  conditions  could  exist, 
because  of  the  varying  texture  in  the  rocks,  if  for  no  other  reason,  and 
hence  horizontality  seldom  occurs. 

103. 


Synclines  of  Mount  Washington,  Mass.     D.  '87. 


In  a  single  ordinary  flexure,  therefore,  the  strike  may  vary  nearly  180°, 
and  the  dip  as  greatly.  For  the  edge  of  the  horizontal  plane  (feg  in  Fig.  104) 
is  a  horizontal  line ;  hence  it  corresponds  to  the  strike  for  each  point  it 
passes  over  through  a  circuit  of  180°.  Supposing  the  flexure  to  run  north 


104. 


and  south,  the  strike  may  vary  from  jST.-S.  through  E.-W.  to  N.-S.  again. 
Further :  since  the  dip  of  the  outer  layer  at  any  point  is  at  right  angles  to 
the  strike,  it  is  at  right  angles  to  the  line  str.  The  dip  of  the  beds  is  least 
along  the  axis  of  the  fold. 

Folds  derive  complexity  also  from  torsion  in  the  upturning  movement. 
The  following  figure  of  a  mountain  scene  in  Colorado  (Fig.  105)  shows, 
besides  the  effects  of  erosion,  those  of  a  twist  or  torsion  in  the  strata.  The 
light-shaded  stratum  has  opposite  dip  in  the  near  and  distant  parts,  and  of 
course  the  strata  either  side  participated  in  the  torsion.  The  effect  is  proba- 
bly far  more  common  than  is  believed,  for  only  in  a  region  of  bare,  uncovered 
rocks  is  such  a  condition  likely  to  be  appreciated. 

Besides  the  above-mentioned  irregularities  in  a  region  of  flexures,  others 
come  from  variations  in  the  length  of  parallel  flexures,  one  flexure  lapping 


106  STRUCTURAL   GEOLOGY. 

by  another,  very  much,  like  the  folds  above  the  elbow  in  a  woolen  coat- 
sleeve.  The  flexures  are  those  of  a  warped  surface,  parallel  usually  in 
direction,  but  mutually  involved  along  their  course.  Hence  there  are  large 
variations  in  dip  between  the  flexures. 

105. 


Upturned  strata  of  the  west  slope  of  the  Elk  Mountains,  Colorado.     The  light-shaded  stratum,  Triassico. 
Jurassic;  that  to  the  right  of  it,  Carboniferous;  that  to  the  left,  Cretaceous.    Holmes,  Gardner. 

Models  of  flexures  may  be  conveniently  made  out  of  a  large  unhewn  branch  of  a  tree 
of  coarse-grained  wood,  having  the  bark  on.  A  piece  of  the  branch  (3  or  4  inches  or 
more  in  diameter)  12  to  18  inches  long,  cut  obliquely  from  a  diametral  line  at  one  end 
at  an  angle  of  20°  or  so,  will  afford  two  models  of  a  flexure  with  an  inclined  axis.  By 
coloring  groups  of  layers  in  the  wood,  using  for  greater  simplicity  not  more  than  three 
colors,  the  appearances  of  the  flexed  strata  may  be  studied  in  horizontal,  vertical,  and 
any  other  sections  that  may  be  cut.  Such  models  might  be  made  by  pasting  together 
sheets  of  differently  colored  paper,  or  layers  of  paper-pulp,  and  so  making  a  cylinder,  and 
then  cutting  it  as  above.  By  pressure  the  cylinder  might  be  made  elliptical,  and  models 
might  be  obtained  with  unequal  dips  on  the  two  sides. 

Geanticlines,  geosynelines.  —  The  flexures  in  rocks  which  have  been  above 
described  and  illustrated  by  figures  are  flexures  of  the  strata  of  the  earth's 
exterior,  or  the  supercrust,  not  of  the  crust  itself.  The  crust  is  thick,  and 
it  is  impossible,  were  it  but  10  miles  thick,  that  it  should  be  bent  into 
so  small  and  abrupt  flexures.  It  has,  however,  its  own  great  flexures  of  low 
angle  and  of  great  breadth,  both  upward  and  downward.  It  is  proved  that 
the  stratified  rocks  of  the  Alleghanies  were  laid  down  in  one  such  downward 
bend  or  trough,  a  thousand  miles  long,  during  the  long  ages  in  which  it  was 
slowly  deepening.  There  are  also  evidences  that  upward  bends  of  similar 
extent  have  been  made.  These  flexures  of  the  crust  are  termed  geanticlines 
and  geosyndines,  the  prefix  in  these  terms  being  derived  from  the  Greek 
word  for  earth.  The  basin  of  Lake  Superior  probably  corresponds  to  a 
geosyncline,  as  suggested  by  T.  C.  Chamberlin. 

Fractures,  faults,  compression  and  stretching  of  rocks.  —  The  fractures 
intersecting  rocks  are  of  all  sizes,  from  those  small  cracks  that  result  from 
contraction  on  drying  and  cooling,  and  from  gravitational  pressure  on  strata 
of  varying  compressibility  or  of  insufficient  support,  to  those,  sometimes 
miles  in  depth,  that  are  made  in  the  grander  movements  of  the  earth's 
crust. 


TEKKANES.  107 

Kocks  vary  greatly  in  fragility,  and  break  very  differently  under  the  same 
circumstances.  Some,  as  the  shales  and  argillaceous  sandstones,  yield  to 
pressure  by  bending  or  by  becoming  compressed  or  stretched;  or,  like  a 
friable  sandstone,  become  adapted  to  the  pressure  as  might  a  bag  of  corn, 
by  a  readjustment  of  the  grains.  But  the  more  solid  sandstones,  having  less 
mobile  elements,  become  divided  into  blocks,  unless  the  pressure  at  work  is 
of  the  extremest  slowness ;  and  compact  limestone,  the  most  brittle  of  rocks 
when  pure,  breaks  into  smaller  blocks,  and  sometimes  into  multitudes  of 
them.  The  fractures  due  to  stretching  or  tension  are  often  large  in  the 
summit  portion  of  an  anticline,  and  especially  when  the  beds  consist  of  the 
harder  or  more  brittle  rocks.  If  a  stratum  of  limestone  is  made  up  of  pure 
and  impure  (argillaceous)  layers,  the  former  may  be  broken  into  columns  when 
the  latter  are  sparingly  broken.  Only  a  slight  torsion  from  unequal  pressure 
or  support  is  needed  for  these  results.  The  scenery  of  the  Rocky  Mountain 
region,  and  especially  of  the  Colorado  Canon,  illustrates  finely  these 'various 
differences  in  fragility.  It  is  dependent  upon  the  columnar  fronts  of  many 
of  the  harder  alternating  layers  for  much  of  its  architectural  effect. 

It  has  been  stated  that  the  flexures  in  strata  are  those  of  a  warped  sheet. 
But  while  the  coat-sleeve  loses  its  flexures  on  straightening  it,  strata  could 
not  be  restored  to  their  original  condition,  because  of  the  great  stretching 
and  slipping  on  one  another  of  the  beds  in  one  part,  and  of  the  compression 
in  others.  Proofs  of  the  stretching  and  compression  are  afforded  by  the 
deformation  of  fossils,  as  illustrated  in  the  chapter  on  mountain-making. 
(See  page  370.)  The  smallest  of  fractures  that  have  geological  importance 
are  those  of  the  constituent  grains  or  crystals  of  a  crystalline  rock,  which 
are  generally  so  minute  as  to  be  detected  only  by  microscopic  investigation. 
They  sometimes  indicate  a  flowing  of  the  material,  lava-like,  before  it  had 
cooled,  or  contraction  during  cooling,  or  some  progressing  change  of  form 
through  pressure. 

Faults  are  displacements  along  fractures.  When  a  coal-bed  is  not  con- 
tinuous across  a  plane  of  fracture,  but  has  its  continuation  at  some  higher  or 
lower  level,  a  fault  exists ;  and  such  faults  often  occasion  much  trouble  to 
miners.  There  may  be  a  few  inches  or  less  of  displacement,  or  a  few  feet ; 
but  the  larger  faults  of  mountain-making  regions  are  sometimes  10,000  to 
20,000  feet. 

In  Figs.  106,  107,  ft  is  the  course  of  a  fracture,  and  a  to  b  the  amount  of 
displacement.  In  Fig.  106  the  part  to  the  right  has  slipped  down  against  the 
opposite  wall,  or  there  is  a  downthrow ;  and  this  downthrow  is  in  the  direc- 
tion of  the  dip  (or  the  hade,  in  miners'  language)  of  the  fracture-plane.  In 
Fig.  107,  the  reverse  is  the  case ;  there  is  an  upthrust  along  this  plane.  One 
is  an  overthrow  or  downthrust  fault,  the  other  an  upthrust  fault.  The  angle 
of  dip  in  the  fault-plane  is  here  near  60° ;  but  it  may  be  from  0°  to  90°. 

In  Fig.  108  a  block  of  the  formation  has  slipped  down  between  two  frac- 
ture planes ;  moreover,  the  resistance  or  friction  has  produced  a  bending  of 
the  layers  on  one  side.  Ee verse  the  figure,  and  another  condition  in  faulted 


108 


STKUCTUEAL   GEOLOGY. 


strata  is  represented.     The  surfaces  of   walls  often  become  scratched  or 
"  slickensided  "  by  the  movement. 


106. 


107. 


108. 


It  cannot  be  affirmed  in  all  cases  that  the  downthrow  or  upthrust 
exhibited  in  the  beds  was  the  whole  movement,  but  only  that  it  was  the 
final  differential  result  of  whatever  up  or  down  movement  took  place. 

Often  there  are  many  small  faults  in  a  group,  as  in  the  annexed  figure ; 
and  the  group  may  be  of  the  downthrow  or  upthrust  kind,  though  usually  in 
such  cases,  of  the  former.  Frequently  one  or  two  blocks  in  the  group  of  a 
displacement  has  undergone  a  reverse  movement ;  but  this  does  not  change 
the  general  character  of  the  faulting. 


109. 


110. 


Faulted  by  beds. 


Fault  with  opened  fissure  filled  with  fallen 
Powell,  '75. 


Fig.  110  (from  Powell)  shows  a  downthrow  fault  along  a  vertical 
fracture  ;  moreover,  the  fracture  is  opened  so  as  to  become  a  wide  fissure, 
and  the  fissure  is  filled  with  masses  from  the  inclosing  rocks.  For  other 
faults  in  fissures  (veins),  see  pages  328-330. 

Doivnthrow  faults  are  often  called  normal  faults ;  but  only  from  the  fact 
that  they  are  most  common.  The  smaller  faults  are  usually  of  this  kind, 
since  gravity  acts  that  way.  The  great  faults,  thousands  of  feet  in  dis- 
placement, are  often  upthrust  faults.  Those  in  the  Appalachian  Mountain 
region  of  Pennsylvania  and  Virginia  have  the  upthrust  of  the  enormous 
extent  above  stated,  10,000  to  20,000  feet ;  and  the  beds  of  the  eastern  side 
would  now  have  this  great  height  above  those  on  the  opposite  side  were  it 
not  that  running  waters  of  the  sea  and  land  (mostly  the  latter)  had  worn  all 
down  to  a  common  level.  A  section  of  one  of  these  great  faults  of  Virginia, 
and  the  worn-off  condition  of  the  beds,  is  shown  in  Fig.  111.  On  one  side  of 


TERRANES. 


109 


the  fault  F  are  coal-beds,  on  the  other,  one  of  the  lower  limestones  of 
the  geological  series,  which,  by  upthrust  action,  has  been  put  on  a  level 
with  the  coal-formation.  By  the  same  forced  movements,  downward  dis- 
placements or  faults  are  sometimes  made,  and  these  have  been  distinguished 


111. 


Section  of  the  Paleozoic  formations  of  the  Appalachians,  in  southern  Virginia,  between  Walkers  Mountain 
and  the  Peak  Hills  (near  Peak  Creek  Valley)  :  F,  fault;  a,  Lower  Silurian  limestone;  6,  Upper  Silurian; 
c.Devonian;  d,  Subcarboniferous  with  coal-beds.  Lesley. 

from  the  gravity-made  downthrow  faults  by  using  the  term  downthrust  fault 
(E.  A.  Smith). 

The  following  figures  show  that  after  erosion  the  same  surface  features 
may  result  from  a  downthrow  (Fig.  112)  along  a  vertical  fracture  and  from 


112. 


113. 


114. 


an  upthrust  (Fig.  113)  along  an  oblique  fracture;  the  dip  of  the  fracture- 
plane  is  here  about  25°. 

Not  unfrequently  a  flexure  changes,  in  one  direction  or  the  other,  into  a 
fault,  showing  that  the  force  causing  the  break  first  produced,  as  is  natural, 
a  bend.  Many  examples  of  such  flexure-faults  have  been  described  by  Major 
Powell,  and  later  by  others,  from  the  plateaus 
of  Colorado,  where  the  absence  of  vegetation 
and  soil  affords  unusual  opportunities  for  ob- 
servation on  the  positions  and  inside  con- 
dition of  strata.  A  bend  (Fig.  114,  from 
Powell)  represents,  ideally,  the  upper  layer 
of  a  region  of  a  low  anticline  in  the  eastern 
part  of  the  Uinta  Mountains.  The  bend  in 
the  part  to  the  right  shows  that  a  fracture 
is  begun ;  and  in  Fig.  115,  which  represents 
the  same  line  of  faulting,  the  actual  displacement  amounts  to  thousands  of 
feet. 

A  succession  of  monoclines  along  faults  produces,  in  the  region  of  the 
Colorado  plateaus,  the  features  shown  in  Fig.  116,  from  Powell ;  and  Fig. 
117,  from  the  same  region,  illustrates  a  section  across  a  large  fault  having 
two  branches. 


115. 


Flexure-fault.     Powell,  '76. 


110 


STRUCTURAL   GEOLOGY. 


Figs.  118,  119,  120  illustrate  a  flexure-fracture  and  fault  along  the  syn- 
cline  of  an  overthrust  flexure  in  the  Alps,  some  thousands  of  feet  in  span,  as 
figured  by  Heim.  It  will  be  observed  that  the  strata  became  bent  without 


116. 


117. 


Succession  of  monoclines;  section  across  a  branching 
fault.     Powell,  '75. 


Section  across  a  branching  fault.    Powell,  '75. 


breaking  till  the  flexures  of  Fig.  118  were  produced,  illustrating  thus  the 
important  fact  that  the  bending  of  flexed  rocks  has  in  all  cases  gone  forward 
with  extreme  slowness.  The  plane  of  the  flexure  from  a  to  &,  between  the 

118.  110. 


A  fold  passing  into  a  fault,  from  the  Alps.     Heim,  '78. 

anticline  and  syncline,  is  the  plane  of  greatest  weakness,  and  hence  the 
fracture.  There  is  usually  much  stretching,  also,  and  thinning,  of  the  beds 
along  the  fracture.  The  fault  at  the  bend  in  Fig.  120  is  an  upthrust  fault, 
the  stratum  m  to  the  right  being  the  same  with  n  to  the  left ;  and  the  exist- 
ing distance  between  the  two  is  a  measure  of  the  extent  to  which  the  strata 
were  pushed  up  the  sloping  fault-plane.  Where  the  flexures  are  closely 
crowded  together,  the  faults  may  divide  up  a  bed  into  many  parts ;  and  if 
a  bed  of  iron  ore  is  in  the  series,  its  parts  may  be  so  far  displaced  and  cut  up 
into  so  small  sections  as  to  make  it  unprofitable  to  attempt  to  follow  it. 

The  great  upthrust  faults  made  along  fractures  many  thousands  of  feet 
in  depth,  like  those  of  the  Appalachians,  have  usually  taken  place  along 
fracture-planes  of  small  dip  —  between  20°  and  45°.  Downthrow  or  down- 
thrust  faults,  however  great  the  displacement,  may  occur  along  fracture- 
planes  of  all  slopes  to  verticality. 

The  region  of  the  great  elevations  produced  along  such  faults  in  the 
Appalachians  has  been  reduced  in  general  to  a  level  below  that  of  the 


TERRANES.  Ill 

mountain-summits.  The  faulted  region,  because  a  region  of  fractures,  is,  in 
general,  the  course  of  a  great  valley. 

Fissures  also  are  faulted  in  the  several  ways  mentioned,  because  they 
are  in  the  terranes,  and  must  share  in  the  displacements.  They  may  be 
faulted  even  at  the  time  when  they  are  first  made,  and  faulted  at  various 
later  periods. 

Besides  faults  of  up-and-down  displacement,  there  are  also  (1)  longitu- 
dinal faults,  and  sometimes  without  much  change  of  level  in  the  beds. 
More  common  than  either  vertical  or  longitudinal  faults  are  (2)  the  oblique, 
since  resistance  and  pressure  would  seldom  be  so  equable  as  to  prevent 
obliquity.  (3)  Horizontal  displacement  of  strata  also,  occur,  and  sometimes 
of  marvelous  extent.  They  are  produced  by  a  horizontal  or  oblique*  thrust 
shoving  terranes  over  others.  In  a  case  reported  from  the  Scottish  High- 
lands, a  mass  of  the  oldest  crystalline  rocks,  many  miles  in  length  from 
north  to  south,  was  thrust  at  least  ten  miles  westward  over  younger  rocks, 
part  of  the  latter  fossiliferous. 

(4)  Bed-plane  faults  are  still  another  kind  in  which  the  plane  of  displace- 
ment is  that  between  two  layers  or  strata.     They  are  produced  by  the  push- 
ing of  one  bed  or  stratum  of  a  series  over  the  surface  of  that  below  it.     In 
the   Triassic  of  East  Haven,   Conn,    (on  the  borders  of  New  Haven),  the 
successive  beds  of  the  red  granitic  sandstone  (which  dip  eastward  15°  to  20°) 
have  been  shoved  over  one  another  upward  along  the  plane  of  bedding, 
producing  large  and  general  displacements,  and  great  slickensided  surfaces ; 
and  these  surfaces  have  generally  a  very  thin  and  hard  white  coating,  ap- 
parently due  to  the  ground-up  feldspar.     In  the  same  region,  besides  these 
shoves  of  layers  over  one  another,  there  are  also  ordinary  faults  with  slick- 
ensided walls;  and  in  many  places  the  rock  is  in  fragments,  and  all  the 
fragments,  even  those  no  larger  than  the  hand,  indicate  participation  in  the 
movement  by  the  slickensides  which  cover  them. 

(5)  Pressure  has  sometimes  produced  a  crushing  of  the  rocks  along  frac- 
tures, either  directly  or  aided  by  lateral  movement,  making  what  has  been 
called  in  the  latter  case  shear-zones. 

(6)  In  the  upturning  and  flexing  there  has  also  been  slipping,  by  the 
inch  and  fractions  of  an  inch,  along  planes  of  cleavage  or  bedding,  making 
slip-faults,  and  producing  also  small  flexings  or  crumplings  of  the  beds. 

Jointed  structure,  joints.  —  A  jointed  structure  is  a  style  of  fracturing, 
usually  on  an  extended  scale,  in  which  there  is  a  degree  of  system  in  the 
arrangement  of  the  fractures.  The  divisional  planes  are  termed  joints. 
They  cut  across  the  stratification,  and  may  have  great  extent  vertically  and 
laterally.  The  planes  of  division  are  often  very  even,  and  not  enough  open 
to  admit  the  thinnest  paper.  They  may  be  in  one,  two,  or  more  directions 
in  the  same  rock,  and  extend,  with  nearly  uniform  courses,  through  regions 
that  are  many  miles  in  length  or  breadth.  The  accompanying  sketch  repre- 
sents the  falling  cliffs  of  Cayuga  Lake,  and  the  fortress-shapes  and  buttresses 
arising  from  the  natural  joints  intersecting  the  rocks.  The  wear  of  the 


112 


STRUCTURAL   GEOLOGY. 


waters  from  time  to  time  tumbles  down  an  outer  range,  and  exposes  a  new 
series  of  structures. 

Traversing  the  surface  of  a  region  thus  intersected,  the  joints  appear  as 
mere  fractures,  and  are  remarkable  mainly  for  their  great  extent,  number, 


121. 


12-2. 


Jointed  rocks,  Cayuga  Lake.    Hall,  '43. 

and  uniformity.  In  case  of  two  systems  of  joints,  —  the  case  most  common, 
—  the  rock  breaks  into  blocks,  which  are  rectangular  or  rhomboidal,  accord- 
ing as  the  joints  cross  at  right  angles  or  not.  The  main  system  of  joints  is 
sometimes  parallel  to  the  strike  of  the  uplifts,  or  else  to  the  range  of  eleva- 
tions or  mountains  in  the  vicinity,  or  to  some  general  mountain  range  of  the 
continent. 

In  many  cases,  a  rock  is  so  evenly  and  extensively  jointed  as  to  become 
thereby  laminated,  and  in  such  a  case  the  joints  may  be  easily  mistaken  for 
planes  of  stratification,  especially  when  the  latter  have  been  obliterated. 
Sometimes  there  are  sudden  transitions  from 
the  regular  stratification  to  vertical  joints,  as 
in  Fig.  122.  This  case  occurs  in  a  section  of 
part  of  a  quartzyte  bluff  on  the  railroad  near 
Poughquag,  Dutchess  County,  N.Y.  a,  a,  a 
are  ordinary  joints  in  the  stratified  rock;  b,  b 
is  a  portion  of  the  rock,  which  has  lost  its 
stratification  entirely,  and  has  become  jointed 
vertically ;  the  transition  from  the  stratified 
to  the  part  b,  b  is  so  abrupt  that  the  latter  has 
the  aspect  of  an  intersecting  dike,  or  of  a  portion  of  the  laminated  sandstone 
set  erect.  It  occurs  in  sand-beds,  whose  grains  adjust  easily,  like  shot,  to 
pressure. 

Fig.  124  represents  a  rock  with  two  cleavage-directions;  and  125  a  quartz- 
ose  sandstone  which  has  irregular  cleavage-lines.  These  last  two  cases, 
together  with  that  represented  in  Fig.  122,  appear  to  show  that  the  jointed 
structure  and  slaty  cleavage  may  have  a  similar  origin. 

/Slaty  and  foliated  structure.  —  In  the  slaty  structure,  or  slaty  cleavage, 
the  rock  is  divided  into  thin  even  sheets  or  laminae,  as  in  the  case  of  roofing- 
slate  or  writing-slate.  The  laminated  structure  of  shales  is  parallel  to  the 
bedding,  and  is  due  to  the  conditions  of  deposition  and  the  pressure  of  super- 


Jointed  quartzyte.    D.  '72. 


TERRANES. 


113 


incumbent  beds ;  but  slates  have  received  their  structure  from  lateral  pres- 
sure, and  it  often  crosses  the  bedding,  as  in  Figs.  126, 127.     This  structure  is 


123. 


125. 


Jointed  rocks.    De  la  Beche. 


Slaty  cleavage,  Columbia  Co.,  N.Y.    Mather,  '43. 


also  called  the  foliated  structure.     The  sections  represented  in  Figs.  126,  127 
are  from  the  slate  region  of  Columbia  County,  N.Y. 

Occasionally,  the  lines  of  deposition  are  indicated  by  a  slight  flexure  in 
the  slate  near  them,  as  in  Fig.  127.  In  other  cases  there  is  a  thin  intermedi- 
ate layer  which  does  not 

partake  of  the  cleavage.  126m  12"- 

Fig.  123  represents  an  in- 
terstratification  of  clay- 
layers  with  limestone,  in 
which  the  former  have 
the  cleavage,  but  the  lat- 
ter not,  though  the  lime- 
stone sometimes  shows  a  tendency  to  it  where  argillaceous. 

Sedgwick  first  detected  the  true  lines  of  bedding,  and  ascertained  that 
the  slaty  structure  was  one  that  had  been  superinduced  upon  the  clayey 
strata  by  some  process  since  they  were  first  deposited. 

The  schistose  structure  of  crystalline  rocks,  or  their  schistosity,  as  it  is 
often  termed,  may  be  produced  by  pressure ;  and  hence  all  schistose  struc- 
ture, and  even  the  fainter  parallelism  of  the  planes  of  a  foliated  mineral  like 
mica,  as  in  granitoid  gneiss,  are  often  termed  foliated.  The  regular  fractures 
producing  a  jointed  or  a  slaty  structure  are  named  diaclases  by  Daubre"e, 
and  fractures  accompanied  by  displacement,  paraclases. 

4.    Calculating  the  Thickness  of  Strata. 

When  strata  are  inclined,  as  in  Fig.  128,  the  thickness  is  ascertained  by 
measuring  the  extent  along  a  horizontal  surface,  and  also  the  angle  of  dip, 
and  then  calculating  the  thickness  by  trigonometry.  The  thickness  of  the 
strata  from  a  to  ft  is  bd,  the  line  bd  being  drawn  at  right  angles  to  the 
strata.  Measuring  ab  and  the  dip,  which  is  the  angle  bad,  the  angles  and 
hypotenuse  of  the  triangle  abd  are  given  to  determine  one  side  bd.  Or, 
with  the  distance  ae,  the  side  ce  would  be  found. 

But  for  correct  results,  the  absence  of  faults  must  be  first  ascertained. 
DANA'S  MANUAL  —  8 


114 


STRUCTURAL   GEOLOGY. 


128. 


129. 


The  figure  (128)  represents  a  fault  at  bg,  so  that  the  strata  1,  2,  3,  4  to  the 
left  are  repeated  to  the  right ;  and  hence  the  whole  thickness  is  bd  instead 

of  ce.  ab  is  the  width  at  surface  of 
the  strata  1,  2,  3,  4 ;  but  by  the  fault, 
ab  is  increased  to  ac.  There  may 
be  many  such  faults,'  in  the  course 
of  a  few  miles ;  and  each  one  would 
increase  the  amount  of  error,  if  not 
guarded  against. 
'*>  So  other  faults  might  go  on  in- 

creasing the  extent   of   the  surface 

exposure.  This  is  further  illustrated  in  Fig.  129.  Let  A  be  a  stratum 
10,000  feet  thick  (a  to  c)  and  100,000  feet  long  (a  to  b).  Let  it  now  be 
faulted,  as  in  Fig.  B,  and  the  parts  uplifted  to  a  dip  of  15°,  —  taking  a 
common  angle  for  the  parts,  for  the  sake  of  simplicity  of  illustration.  The 
projecting  portions  being  worn  off  by  the  ordinary  processes  of  denudation, 
it  is  reduced  to  Fig.  C,  mn  being  the  surface  exposed  to  the  observer. 
The  first  error  that  might  be  made  from 
hasty  observation  would  be  that  there  were 
four  distinct  outcropping  coal  layers  (call- 
ing the  black  layer  thus),  instead  of  one; 
and  the  second  is  the  one  above  explained 
with  regard  to  calculating  the  thickness  of 
the  whole  stratum  from  the  entire  length 
mn  in  connection  with  the  dip.  Very 
often  the  beds  have  been  shoved  up  over 
one  another  in  the  making  of  a  monocline 
to  such  an  extent  that  the  faults  are  almost 
or  wholly  obliterated.  A  calculation  of  the 
thickness  in  such  a  case  is  impossible. 

If  the  stratum  (Fig.  129  A)  were  in- 
clined 15°  without  faulting,  it  would  stand  as  in  D ;  and  if  then  worn  off  to 
a  horizontal  surface,  the  widest  extent  possible  would  be  cr,  which  is  less 
than  half  what  it  has  with  the  three  faults.  A  block  of  the  size  mentioned 
would  require,  in  order  to  make  it  a  monocline  of  45°,  that  one  end  should 
be  dropped  down  70,000  feet,  or  the  other  end  raised  as  much,  or  that  this 
amount  of  change  should  be  divided  between  the  two  ends ;  and  for  a  mono- 
clinal  block  having  a  dip  of  60°,  the  drop-down  or  upthrust  would  have  to 
be  nearly  87,000  feet,  or  more  than  16  miles.  Calculating  the  thickness  from 
the  dip  in  a  region  is  liable,  therefore,  to  enormous  error. 

5.    Conf or  mobility,  Unconf or  viability. 

Successive  strata  in  a  region  may  be  conformable  to  one  another  or  uncon- 
formable.  In  the  series  of  strata  made  over  the  earth's  crust,  the  rocks 
of  successive  periods  and  ages  have,  in  large  parts  of  the  world,  been  made 


B  m— 


TERRANES.  115 

in  regular  succession,  each  stratum  conformable  in  bedding  to  the  preceding. 
This  was  true  of  the  40,000  feet  of  rock  of  the  Appalachian  region  (referred 
to  on  page  353),  out  of  which  the  Appalachian  Mountains  were  finally  made. 
This  is  an  example  of  conformabUity,  as  the  term  is  used  in  geology. 
Through  the  long  series  there  is  conformity  in  bedding. 

But  these  conformable  strata  rest  on  older  rocks  that  have  the  bedding 
upturned  and  standing  at  various  angles.  Between  the  two  there  is  uncon- 
formability  in  bedding. 

Fig.  130  illustrates  this  subject.  The  beds  2,  3,  4a,  46,  are  conformable 
to  one  another,  but  unconformable  to  the  flexed  rocks  numbered  1.  The 

130. 


1,  Upturned  Archaean  rocks;  2,  3,  4a,  46,  overlying  strata,  conformable  with  one  another,  but  uuconformable 

with  the  Archaean.      Logan. 

flexing  of  the  rocks  antedated  the  deposition  of  No.  2;  and  knowing  the 
geological  age  of  No.  2,  some  approximation  is  made  toward  a  knowledge  of 
the  time  of  flexure.  There  may  be  three  or  four  cases  of  unconf or m ability 
in  the  same  region.  For  in  each  mountain-making  epoch,  new  rocks  are 
upturned,  and  the  succeeding  ones  are  laid  down  horizontal,  as  usual,  over 
the  upturned.  Such  unconformabilities  belong  especially  to  regions  of  moun- 
tain-making; for  there  occur  the  upturned  rocks.  Only  a  few  miles  away 
from  the  region  of  the  mountain,  the  rocks  that  are  unconformable  in  the 
latter  may  rest  on  one  another  in  regular  order,  or  conformably,  as  if  no 
disturbance  had  anywhere  taken  place. 

The  preceding  figure  has  a  fault-plane  at  /,  and  there  is  an  unconformity 
between  the  beds  on  each  side  of  it,  but  not  unconformability.  The  uncon- 
formity introduced  by  faults  is  easily  mistaken  for  true  unconformability. 
Such  unconformity  is  of  frequent  occurrence  in  all  formations ;  while  uncon- 
formity in  bedding  indicates  an  epoch  of  mountain-making,  a  thing  of  rare 
occurrence  in  the  geological  history  of  a  region. 

Besides  this  most  important  species  of  unconformability,  that  of  the  first 
kind,  there  are  also  two  other  kinds :  (1)  through  changed  sea-limit  or 
overlap;  (2)  through  surface  erosion. 

Tlirough  overlap. —  When,  after  the  deposition  of  beds,  a  slight  sinking 
of  the  region  takes  place,  the  next  deposits  there  made  may  extend  beyond 
the  limits  of  the  preceding,  and  overlap  those  outside.  In  such  cases, 
although  both  deposits  are  approximately  horizontal,  there  is  still  a  degree 
of  unconformability.  Oscillations  of  the  land  surface,  or  of  the  water  level, 
have  gone  on  through  the  successive  periods,  so  that  unconformity  by  overlap 
is  of  very  frequent  occurrence,  and  of  minor  significance,  though  always  of 
great  geological  interest. 


116  STRUCTURAL   GEOLOGY. 

Through  an  interim  of  erosion.  —  Between  the  time  of  making  two  suc- 
cessive horizontal  strata  there  is  sometimes  an  interval  of  exposure  to 
marine  or  fluvial  erosion,  which  the  worn  upper  surface  of  the  lower  stratum 
indicates.  This,  also,  is  unconformability  in  geology,  and  as  the  interim  of 
erosion  may  be  long,  it  is  of  importance.  Yet  in  all  periods,  as  in  that 
of  existing  time,  the  deposits  made  during  a  period  may  be  extensively 
worn  away  in  some  large  regions  before  the  period  has  closed ;  partly  worn 
away  in  many  places  it  is  sure  to  be.  An  uplift  of  600  feet  in  the  present 
era,  putting  a  coral  reef  rock  this  much  above  the  sea,  is  followed  by  cave- 
making  and  extensive  removals.  The  amount  of  erosion  is  no  certain 
evidence  as  to  the  length  of  time  during  its  progress. 

Deposits  are  sometimes  formed  in  basins  or  depressions  of  the  surface. 
Such  deposits  may,  in  general,  be  distinguished  by  their  thinning  out  toward 

the  sides  of  the  basin.  Yet,  when  syn- 
clinal valleys  are  shallow,  it  is  easy,  and 
not  uncommon,  to  mistake  beds  that  are 
conformable  with  the  strata  below  for  such 
basin  formations.  The  beds  ab  (Fig.  131) 
lie  in  the  synclinal  valley  mn,  like  a  basin 

deposit;  but  they  were  formed   before  the  folding   of  the   beds,  and  not 
after  it. 

UNSTRATIFIED  TERRANES. 

The  unstratified  terranes  comprise  (1)  the  great  unstratified  masses  of 
granite  and  other  related  crystalline  rocks  ;  (2)  the  various  masses  of  ejected 
igneous  rocks  that  lie  in  piles,  not  having  the  bedding  due  to  successive 
flows,  and  not  making  part  of  any  stratified  series;  (3)  masses  occupying 
fissures  in  the  earth's  crust  or  supercrust,  and  having  thereby  the  nature 
either  of  dikes  or  veins. 

The  facts  connected  with  unstratified  terranes  are  necessarily  considered 
in  Part  III.  on  Dynamical  Geology,  and  remarks  here  are  therefore 
unnecessary. 


PAET    III. 


DYNAMICAL    GEOLOGY. 

DYNAMICAL  GEOLOGY,  as  explained  on  page  14,  treats  of  the  causes  of 
events  in  the  earth's  geological  progress.  These  events  include :  I.  Those 
concerned  in  the  production  and  modification  of  the  earth's  rock  structure, 
and  in  the  development  of  its  form  and  features.  II.  The  changes  in  the 
earth's  climates.  III.  The  changes  through  geological  time  in  the  earth's 
vegetable  and  animal  life.  The  explanations  beyond  relate  mainly  to  the 
first  of  these  classes  of  subjects.  The  succession  in  climates  and  in  vege- 
table and  animal  life  is  considered  only  historically,  under  Historical 
Geology. 

The  chief  of  the  agencies  directly  concerned  in  geological  work  are  the 
Atmosphere,  the  Waters,  Heat,  Chemical  Force,  and  Life,  each  acting  through 
or  under  general  physical  laws. 

The  atmosphere  and  the  waters,  by  means  of  which  most  rocks  have  been 
made,  valleys  excavated,  mountains  shaped,  and  a  great  amount  of  chemical 
work  carried  on,  are  the  most  prominent  of  the  earth's  exterior  agencies. 
Life,  in  its  geological  work,  is  another  of  the  exterior  agencies.  Heat  has 
both  an  exterior  and  an  interior  source,  with  corresponding  effects.  As 
exhibited  in  igneous  ejections  and  volcanoes  it  is  an  interior  agent  both  in 
source  of  material  and  of  force ;  but  the  distribution  of  ejected  material  has 
taken  place  in  part  by  means  of  the  exterior  agencies,  water  and  air.  The 
agencies  that  have  made  continents,  oceanic  depressions,  and  mountain  ranges 
are  largely  interior  in  the  origin  of  their  forces  and  in  their  work. 

There  are  three  chief  sources  of  energy  for  these  agencies :  — 

1.  THE  EARTH'S  ROTATION  ON  ITS  AXIS,  and  ITS  REVOLUTION  AROUND 
THE  SUN.     (1)  The  rotation  determining  the  earth's  spheroidal  shape,  the 
length  and  alternations  of  its  day,  its  zones  of  climate,  and  the  system  of 
movements  in  physical  agencies ;   (2)  the  revolution,  causing,  in  case  of  col- 
lision with  any  foreign  body  (as  a  meteorite),  a  manifestation  of  force  in  the 
production  of  heat  and  in  violent  mechanical  effects. 

2.  THE  SUN  :  which,  through  its  heat,  light,  and  attraction,  is  the  origin 
of  movements  in  the  air,  oceans,  and  rivers;  the  origin  of  chemical  ac- 
tivity and  growth  in  the  kingdoms  of  life,  and  of  much  chemical  work  in 

117 


118  DYNAMICAL   GEOLOGY. 

inorganic  nature;  and  the  chief  source  of  climatal  conditions  through  all 
time  since  life  began;  which,  further,  in  conjunction  with  the  moon's 
attraction,  is  the  origin  of  the  energy-distributing  tidal  wave,  and  also, 
incidentally  to  the  tidal  movement,  of  tidal  friction,  with  far-reaching, 
adverse,  and  fatal  results  in  the  retarding  of  the  earth's  rotation. 
3.  THE  EARTH'S  INTERIOR  HEAT. 


Dynamical  Geology  is  discussed  beyond  under  the  following  heads :  — 

I.   CHEMICAL  WORK,  as  a  means  of  superficial  changes. 
II.   LIFE,  as  a  geological  agent. 
III.   THE  ATMOSPHERE,  as  a  mechanical  agent. 

IV.  WATER,  as  a  mechanical  agent :  under  the  subordinate  heads  of 
Water  in  general ;  Fresh  waters ;  Oceanic  waters ;  Glaciers  and 
Icebergs. 

V.  HEAT  :  under  the  heads  of  Sources  of  heat  and  their  direct  climatal 
effects ;  Expansion  and  contraction ;  Igneous  action ;  Metamor- 
phism  ;  Veins  and  ore-deposits. 

VI.  HYPOGEIC  WORK,  or  earth-shaping,  mountain-making,  and  the 
attendant  phenomena. 

I.    CHEMICAL  WORK. 

Chemical  work  is  given  the  first  place,  because  superficial  chemical 
changes  have  been  a  prominent  cause  of  the  decomposition  of  rocks,  and 
thereby  one  of  the  producers  of  the  earth,  clay,  and  other  fragmental  ma- 
terials which  are  worked  into  beds  by  the  mechanically  acting  air  and  waters. 
It  is  also  a  source  of  superficial  rock  formations  of  different  kinds.  Chemical 
changes  carried  on  at  temperatures  above  the  ordinary,  as  those  of  metamor- 
phism,  are  not  here  considered. 

The  following  is  the  order  of  subjects :  1,  Solution ;  2,  Oxidation  and 
Deoxidation ;  3,  Hydration,  or  the  chemical  absorption  of  water ;  4,  Carbonic 
acid  (C02)  and  humus  acids  as  geological  agents ;  5,  Action  of  siliceous  solu- 
tions ;  6,  Chemical  work  of  living  organisms  ;  7,  Mechanical  work  of  chemical 
products  ;  8,  Concretionary  consolidation. 

Of  this  large  subject  only  a  brief  review  of  the  more  prominent  facts  is 
possible  in  this  place. 

SOLUTION. 

The  water  descending  in  rains  takes  from  the  atmosphere  its  elements 
(in  the  ratio  of  about  two  parts  of  nitrogen  to  one  of  oxygen)  ;  carbonic  acid ; 
some  sulphates  and  ammonium  nitrates,  especially  about  cities  where  there 
are  coal  fires ;  and  three  or  four  parts  in  10,000  of  sodium  chloride  or  common 
salt  in  the  vicinity  of  the  ocean ;  besides  atmospheric  dust,  enough  of  which 
is  from  organic  sources  to  make  the  waters  offensive  after  standing  a  few 


CHEMICAL    WORK.  119 

days.  It  gathers  other  materials  as  it  flows,  taking  them  from  the  soil  and 
its  organic  decompositions,  and  from  rocks  or  minerals,  and  especially  where 
decompositions  are  in  progress.  It  finds  soda  and  potash  in  rocks  containing 
feldspars ;  lime  and  magnesia,  in  limestones  and  also  more  or  less  in  many 
other  rocks,  fragmental  and  crystalline  ;  and  various  other  materials  in  these 
and  other  rocks.  Among  the  materials  gathered  up,  the  chief  are  calcium 
carbonate ;  salts  of  iron ;  magnesium,  sodium  and  potassium  carbonate,  sul- 
phate or  chloride;  calcium  chloride;  humus  acids  from  the  soil;  and  carbonic 
acid  from  the  soils  and  other  sources ;  besides,  more  sparingly,  aluminum 
sulphates  and  lithium  salts.  Besides  the  gas  carbonic  acid,  the  waters  often 
receive  and  discharge  hydrogen  sulphide  and  nitrogen,  and  sometimes  the 
gases  hydrogen  and  oxygen.  The  gatherings  depend  on  the  kinds  of  rocks 
washed  by  streams,  both  those  of  the  surface  and  those  of  subterranean 
source.  It  was  long  since  recognized  that,  through  the  gathering  action  of 
fresh  waters,  a  lake  without  outlet  might  become  saline,  like  the  sea. 

The  desert  and  semi-desert  regions  of  the  world  often  illustrate  through 
the  efflorescences  that  exist  over  the  surfaces  of  old  lake  basins,  as  well  as 
the  salts  in  the  waters  of  lakes,  what  solvent  work  the  waters  have  done. 
The  Great  Basin  in  the  west  has  been  studied  with  reference  to  this  subject 
by  King,  Gilbert,  Eussell,  and  others.  The  moisture  below  comes  up  by 
capillary  action ;  and,  as  evaporation  above  is  almost  constant,  owing  to  the 
excessive  dry  ness  and  heat  (90°  F.  the  mean  over  part  of  it  for  July),  so  also 
the  production  of  the  salts  is  in  constant  progress.  The  most  abundant  are 
common  salt  (NaCl),  sodium  carbonate  and  sulphate,  with  often  calcium 
carbonate,  and  borates. 

From  one  of  two  samples  of  the  saline  deposits  from  the  Lahontan  region  analyzed  by 
Dr.  T.  M.  Chatard  were  obtained,  as  cited  by  I.  C.  Russell,  72-69  per  cent  of  sodium  carbo- 
nate (Na2O.CO2),  17-49  of  sodium  sulphate  (Na2O.S03),  4-15  sodium  borate  (Na^O.B406), 
2-53  sodium  chloride  (NaCl),  1-18  potassium  chloride  (KC1),  and  1-96  silica.  In  the 
other  :  9-06  Na^O.COa,  27-05  Na2O.SO3,  1-00  Na2O.B406,  59-32  NaCl,  1-39  KC1,  and  2-18 
Si02.  In  deposits  of  the  dried-up  Sevier  Lake,  south  of  the  Great  Salt  Lake,  Dr.  O. 
Lcew  obtained,  as  reported  by  G.  K.  Gilbert,  (1)  from  those  of  the  center  of  the  lake: 
sodium  sulphate  87-65,  sodium  carbonate  1-08,  sodium  chloride  2-34,  with  water  8-90  = 
99-97  ;  (2)  from  the  middle  or  3d  layer  of  those  of  the  margin,  sodium  sulphate  83-79, 
sodium  chloride  13-84,  magnesium  sulphate  1-33,  potassium  sulphate  0-26,  with  water  0-78  = 
100  ;  from  a  layer  overlying  the  last,  (4th  layer)  sodium  sulphate  2-71,  sodium  chloride 
88-49,  magnesium  sulphate,  potassium  sulphate  0-11,  water  3-40  =  100.  The  above  are  a 
few  of  the  published  analyses.  These  saline  materials  were  once  in  solution  in  lakes  of 
the  region  that  are  now  dried  up. 

Salt  lakes  are  in  some  cases  remnants  of  the  ocean  that  once  covered  the 
land.  But  in  the  Great  Basin,  according  to  Gilbert,  the  saline  ingredients 
have  come  from  the  soil  and  rocks  of  the  region. 

Mineral  springs,  or  sources  of  water  holding  mineral  ingredients  in  solu- 
tion, are  hence  universally  distributed.  They  include  "  pure  "  waters  as  well 
as  the  so-called  "mineral  waters."  The  latter  contain  some  mineral  salt 
generally  in  sufficient  quantities  to  affect  the  taste ;  and  they  are  most 


120  DYNAMICAL   GEOLOGY. 

valued  when  sodium  chloride  is  mostly  absent,  and  when  carbonic  acid  gas 
is  present  to  give  briskness  to  the  waters. 

The  ocean  is  the  great  mineral  spring  of  the  world ;  and  Artesian  borings 
over  the  land  very  often  show,  by  bringing  salt  water  to  the  surface,  that 
more  or  less  sea  water  has  generally  been  left  along  with  the  beds.  About 
3£  per  cent  of  sea  water  consists  of  soluble  salts,  and  of  these  over  f  is 
common  salt.  When  sea  water  along  a  flat  shore  becomes  temporarily 
confined  so  that  it  can  evaporate,  the  salts  are  deposited ;  first  gypsum  or 
anhydrite,  which  goes  down,  according  to  Ursiglio,  when  the  Beaume  areometer 
stands  at  16.75° ;  and  then  the  common  salt  when  it  is  at  26.25°.  While  this 
is  depositing,  the  remaining  solution,  which  is  above,  holds  the  magnesium 
sulphate  and  chloride,  with  the  calcium  chloride,  and  the  iodide  and  borate, 
and  is  called  the  "  mother  liquor  "  or  "  bittern  " ;  and  it  is  all  nearly  ready 
for  deposition,  the  borate  being  among  the  latest  although  not  the  least  solu- 
ble. Magnesium  sulphate  and  magnesium-potassium  chloride  (carnallite) 
make  much  the  larger  part  of  the  final  depositions.  But  a  new  supply  of 
salt  water  at  this  stage  may  prevent  deposition  from  the  bitter  magnesium 
solution  ;  or  the  latter  may  be  gradually  drawn  off  to  mix  again  with  the 
sea  water,  or  for  deposition  elsewhere.  Common  salt  dissolves  in  about  three 
parts  of  either  hot  or  cold  water ;  magnesium  sulphate,  in  about  four  parts 
at  32°  F.,. but  in  one  third  as  much  water  at  212°  F.  Sodium  sulphate  is 
most  soluble  in  warm  water ;  hence  the  waters  of  the  Great  Salt  Lake  deposit 
it  if  cooled  down  to  20°  F.  (Russell). 

The  making  of  salt  in  large  shallow  lagoons  or  "salt-pans"  along  seacoasts,  out  of 
water  let  in  at  high  tide  and  then  confined  for  a  time,  is  a  common  thing  under  the  hot 
sun  of  tropical  countries.  The  same  process  —  solar  evaporation  —  is  used  in  many  regions 
of  brine  springs.  On  some  of  the  smaller  coral  islands  of  the  equatorial  Pacific,  whose 
lagoons  had  become  very  shallow,  there  are  now  beds  of  gypsum  —  sometimes  two  feet 
thick  —  along  with  salt  in  places,  that  were  made  from  the  evaporating  waters  (Hague) , 
showing  that  the  lagoon  basins  had  passed  through  a  salt-pan  condition. 

The  average  composition  of  ocean  water  salts,  in  a  hundred  parts,  has  been  deter- 
mined by  W.  Dittmar  to  be  as  follows:  chlorine  55-292,  bromine  0-188,  sulphuric  acid 
(S08)  6-410,  carbonic  acid  0-152,  lime  1-676,  magnesia  6-209,  potash  1-332,  soda  41-234, 
less  the  oxygen  in  soda  and  magnesia  equivalent  to  the  chlorine  and  bromine  present 
combined  with  the  sodium  and  part  of  the  magnesium  12-493  =  100-00  ;  or  combining  the 
acids  and  bases,  the  salts  are :  sodium  chloride  (common  salt)  77-758,  magnesium-  chloride 
10-878,  magnesium  sulphate  4-737,  calcium  sulphate  3-600,  potassium  sulphate  2-465, 
magnesium  bromide  0-217,  calcium  carbonate  0-345  =  100-00. 

From  these  results  Professor  Dittmar  calculates  for  the  whole  amount  of  salts  in  the 
ocean,  as  follows,  the  unit  being  1,000,000,000,000  tons :  sodium  chloride  35,990,  mag- 
nesium chloride  5034,  magnesium  sulphate  2192,  calcium  sulphate  1666,  potassium  sulphate 
1141,  magnesium  bromide  100,  calcium  carbonate  160  =  46,283  ;  also  total  bromine  87-2 
(Dittmar),  total  iodine  0-03  (Kottstorfer),  total  rubidium  chloride  25-0  (C.  Schmidt). 

The  lime  alone  varies  appreciably  with  the  depth.  As  compared  with  the  amount  of 
chlorine  and  bromine  (the  latter  calculable  as  chlorine) ,  taking  the  amount  at  100,  the  lime 
at  surface  (s),  at  medium  depth  (m),  and  in  the  deep  sea  (d)  was  found  by  Dittmar  to 
be  s,  3-0175;  w,  3-0300;  d,  3-0308.  The  amount  of  carbonic  acid  in  the  waters  above 
what  is  required  for  calcium  carbonate  is  large,  especially  that  at  great  depths  ;  but  it  is 


CHEMICAL  WORK. 


121 


not  sufficient  to  convert  all  the  calcium  carbonate  to  bicarbonate.  Deep  sea  water  affords 
more  or  less  free  oxygen.  (For  Dittmar's  results,  see  Rep.  Chall.  Exp.,  on  ocean  water.) 

The  salinity  or  proportion  of  salts  varies  from  dry  winds,  which  tend  to  concentrate, 
and  from  fresh-water  streams,  which  dilute.  The  area  of  maximum  salinity  in  the  north 
Atlantic  is  the  Sargasso  Sea,  a  region  of  calms  between  25°  and  35°  N.  and  30°  and  20°  W., 
where  the  specific  gravity  is  1-0285  ;  while  that  of  minimum  is  in  the  region  of  equatorial 
rains  between  10°  N.  and  the  equator.  In  the  south  Pacific  there  is  an  area  of  maximum 
specific  gravity  (1-02719)  about  the  Society  Islands.  In  general  the  salinity  decreases 
downward  to  800  or  1000  fathoms,  and  then  increases  to  the  bottom.  In  the  south  At- 
lantic the  specific  gravity  at  the  bottom  is  1-0257  to  1-0259,  but  in  the  north  Atlantic  it 
is  1-02616  to  1-02632  at  2000  to  4000  fathoms  (Buchanan).  In  the  Baltic  Sea,  the  salinity 
is  reduced  one  half  or  more  by  the  waters  from  the  rivers,  and  the  maximum  specific 
gravity  is  only  1-0140.  But  in  the  Mediterranean,  owing  to  evaporation  and  an  average 
rainfall  of  but  30  inches,  the  specific  gravity  is  1-0280  to  1-030 ;  and  hence  the  amount 
of  saline  matters  is  about  3-9  per  cent  to  3-6  for  the  Atlantic. 

The  following  are  analyses  of  two  river  waters,  and  of  two  mineral  springs,  from  a 
paper  by  Professor  C.  F.  Chandler.  The  Croton  River  (supplying  New  York  City)  is  from 
a  region  of  Archaean  rocks  ;  the  Mohawk,  one  of  Lower  Silurian  shales,  sandstones,  and 
limestones  (underneath)  ;  and  the  two  mineral  springs  arise  from  the  Potsdam  sandstone. 
The  amounts  of  mineral  salts  are  of  grains  in  a  U.  S.  gallon  (231  cubic  inches  =  57,750 
grains)  ;  also  mean  of  analyses  of  Arkansas  Hot  Springs,  by  R.  N.  Brackett  (Ark.  Geol. 
Survey),  temp.  124°  and  146-5  F. 


Potassium  chloride. . . 

Sodium  chloride 0-402 

Sodium  bromide ..... 

Sodium  iodide 

Magnesium  chloride. 

Potassium  sulphate 0-179 

Sodium  sulphate 0-260 

Calcium  sulphate .... 
Magnesium  sulphate. . 

Calcium  carbonate 1  -648 

Magnesium  carbonate. . 

Iron  carbonate. 

Silica 0-621 

Organic,  volatile 


Croton  River, 

Mohawk, 

Congress  Springs, 

Lithia  Well, 

Arkansas 

N.Y. 

Utica,  N.Y. 

Saratoga. 

Ballston. 

Hot  Springs. 

— 

0-12 

8-049 

33-276 

— 

0-402 

0-17 

400-444 

750-030 

027 

— 

— 

8-559 

3-643 

— 



— 

0-138 

0-124 

— 

—   Na. 

phosphate  0-016 

0-050 



0-179 

0-889 

0-520 

0-21 

0-260 

0-57 

Na.  Carb.  10-775 

11-928 

0-45 

0-158 

1-31 

Li.  Carb.     4-761 

7-750 

— 

— 

— 

Ba.  Carb.    0-928 

3-881 

Na2CO3  0-04 

1-648 

4-60 

143-399 

238-156 

7-15 

1-100 

1-71 

121-757 

180-602 

1-13 

— 

— 

0-340 

1-581 

FeS04  0-05 

0-621 

0-47 

0-840 

0-761 

2-58 

0-670 

1-64 

trace 

trace 

— 

Total 


5-038        10-68 1 


700-895      1233 -246 2 


11-88 


Pure  water  has  very  feeble  solvent  action  on  rocks  except  in  the  case  of  gypsum  and 
anhydrite,  which  yield  1  part  to  400  to  500  of  cold  water.  Quartz,  feldspar,  and  other 
siliceous  minerals  are  essentially  unaffected.  Only  2  to  10  parts  of  calcite  are  taken  up  by 
100,000  parts.  Opal,  which  is  silica  in  the  soluble  state  (like  that  of  Diatoms,  Sponge- 
spicules,  Radiolarians),  yields  12  to  15  parts  to  100,000  parts  of  cold  water,  and  much  more 
to  warm  water. 


1  The  analysis  afforded  also  0'09  of  alumina  and  iron  oxide. 

2 This  amount  contains  also  0'867  strontium  bicarbonate  and  0'077  alumina;  and  both  the 
Ballston  and  Saratoga  waters  afforded  a  trace  of  calcium  fluoride  and  sodium  biborate.  The 
carbonates  in  these  waters  are  reckoned  as  bicarbonates.  The  Congress  Spring  afforded  392'28J> 
cubic  inches  of  carbonic  acid  to  the  gallon,  and  tbe  Ballston,  426-114. 


122  DYNAMICAL   GEOLOGY. 

Professor  A.  Corsa  subjected  the  rocks  mentioned  below,  after  fine  pulverization,  to  the 
action  of  pure  water  at  65°  F.  for  several  days  ;  the  weight  dissolved  was  as  follows :  — 

Gneiss,  from  Ragogna,  0-1250  per  cent ;  porphyritic  retinite,  from  Monte  Sieva,  0-0562  ; 
perlyte,  of  Monte  Sieva,  0-0024;  phonolyte,  of  Monte  Croci,  0-3260;  trachyte,  of  Monte 
Ortona,  0-0871 ;  granite,  of  Montorfano  (Lago  Maggiore),  0-0727  ;  granite,  of  Baveno  (Lago 
Maggiore),  0-0906. 

Professors  W.  B.  and  R.  E.  Rogers  found  in  their  experiments  (Amer.  Jour.  Sci.,  1848), 
that  under  the  action  of  carbonated  waters,  0-4  to  1  per  cent  of  the  whole  weight  under 
digestion  dissolved  in  only  48  hours. 

DaubrSe  exposed  orthoclase  from  Limoges  in  small  fragments  in  a  vessel  containing 
twice  as  much  water  by  weight  revolving  at  the  rate  of  2550  meters  per  hour.  The  water 
in  8  days,  after  revolutions  equivalent  to  a  flow  of  460  kilometers,  contained  2-52  grams 
of  potash  per  liter,  along  with  0-03  of  alumina  and  0-02  of  silica.  In  salt  water  (water  con- 
taining 3  per  cent  of  NaCl)  there  was  only  a  feeble  alkaline  reaction,  incomparably  less 
than  with  pure  water. 

Water  derives  its  chemical  efficiency  through  the  presence  of  such  impurities 
as  are  ready  to  enter  into  new  combinations.  The  most  common  of  these 
foreign  materials  are  carbonic  acid  (C02),  humus  acids,  and  alkaline  ingredi- 
ents. When  carbonic  acid  is  present  one  part  of  calcite  will  be  taken  up  by 
1000  of  water ;  but  in  this  case  the  material  dissolved  is  not  calcium  carbo- 
nate, but  calcium  bicarbonate.  Again,  the  presence  of  soda  or  potash  gives 
increased  solubility  to  silica  in  its  soluble  or  opal  state,  —  the  state  charac- 
terizing organic  silica. 

The  least  effect  from  moisture  in  rocks  is  diminished  resistance  to 
fracture  or  cohesion.  Part  of  this  is  due  to  the  lubricating  effect  resulting 
from  the  wetting  of  the  grains,  in  consequence  of  which  they  slide  over 
one  another  more  easily  than  when  dry.  On  this  principle  a  grindstone  is 
wet  before  using  it.  But  in  the  case  of  wet  rocks  there  is  often,  perhaps 
generally,  a  solution  of  a  minute  portion  of  some  ingredient  of  the  rock 
which  becomes  solid  again  on  drying.  For  this  reason,  sand  rocks,  whether 
calcareous  or  siliceous,  gradually  harden  at  surface  from  alternate  wetting 
and  drying. 

The  more  prominent  destructive  effects  of  water,  consequent  on  its  solvent 
powers,  are  :  the  easy  erosion  of  beds  of  gypsum  ;  the  rapid  removal  of  beds 
of  salt ;  and  the  injury  to  animal  and  vegetable  life  from  encroachments  of 
mineral  and  marine  waters,  and  to  marine  life  by  its  concentration  on 
evaporation  in  shallow  basins.  The  constructive  effects  are :  the  deposition 
of  salt  and  gypsum  in  large  beds  ;  and  also  the  local  superficial  consolidation 
of  rocks  alluded  to  above. 

OXIDATION  AND  DEOXIDATION. 

On  account  of  the  very  strong  attraction  between  oxygen  and  nearly  all 
the  elements,  and  also  because  this  gas  is  always  at  hand  in  air  and  water, 
it  is  the  most  prominent  agent  in  the  world's  destructive  and  constructive 
chemical  changes. 


CHEMICAL    WORK.  123 

1.  Oxidation  in  inorganic  materials,  —  The  effects  that  have  special  geo- 
logical importance  are  the  slow  oxidation  of  iron,  manganese,  sulphur,  and 
some  other  elements,  which  takes  place  in  the  mineral  constituents  of  rocks 
when  water  and  air  together  have  access.     Little  oxidation  takes  place  under 
water.     The  iron  of  minerals  undergoes  easy  oxidation  when  it  is  present  in 
the  protoxide  state,  FeO,  or  when  combined  with  sulphur.     The  protoxide 
state  is  the  unstable  state  of  iron.     In  oxidizing  it  combines  with  one  half 
more  oxygen,  and  becomes  the  sesquioxide,  Fe203.     This  iron  oxide  is  the 
mineral  hematite  having  a  red  powder,  if  free  from  combined  water ;  but,  if 
containing  water,  limonite,  which  has  a  yellow  or  yellow  brown  color  when 
powdered,  if  not  before  (page  71).     The  latter  rust-colored  oxide  is  like  that 
which  is  produced  when  the  metal  iron  rusts.     But  the  rust  may  contain 
some  carbonate  besides  the  iron  sesquioxide. 

In  a  similar  manner,  when  a  mineral  contains  manganese  protoxide, 
MnO,  the  Mn  tends  to  become  Mn203  or  Mn02,  compounds  that  have  a  black 
powder.  Black  stains,  and  black  crusts  on  marble  and  other  rocks,  after 
weathering,  usually  come  from  the  oxidation  of  some  manganese  in  the  rock. 

The  oxides  FeO  and  MnO  are  unknown  except  in  combination.  But 
magnetite,  Fe304,  is  common  in  disseminated  grains  in  many  rocks,  besides 
sometimes  constituting  thick  beds  ;  it  often  oxidizes  slowly  to  the  sesqui- 
oxide, Fe203 ,  producing  hematite  or  limonite. 

Again:  the  iron  sulphides,  pyrite  and  marcasite,  each  FeS2,  oxidize 
readily,  and  especially  the  latter,  as  shown  by  Julien ;  the  iron,  Fe,  becom- 
ing FeO,  if  there  is  an  acid  ready  to  combine  with  it,  but  otherwise  Fe203 ; 
the  sulphur,  S,  becoming  S03,  and,  with  added  water,  sulphuric  acid.  This 
acid,  with  the  FeO  and  water,  may  make  the  iron  sulphate,  copperas ;  but 
it  may  combine  also  with  Fe203,  and  make  other  sulphates.  If  there  is 
limestone  at  hand,  the  S03,  or  sulphuric  acid,  may  combine  with  the  lime 
and  water,  and  form  gypsum,  and  may  thus  make  beds  of  gypsum.  When 
pyrite  and  marcasite  are  mixed  together,  the  marcasite  makes  oxidation 
easy  (Julien). 

2.  Oxidation  in  organic  materials,  and  other  chemical  changes.  —  When 
life  ceases,  all  organic  materials  tend  to  decay ;  and  in  this  decay,  oxidation 
is  the  chief  process,  and  oxides  the  larger  part,  or  all,  of  the  final  results. 

Wood,  when  thoroughly  dried,  consists  approximately  of  carbon  (C)  49'66, 
hydrogen  (H)  6-21,  oxygen  (0)  43-03,  with  traces  of  sulphur  (S)  and 
phosphorus  (P),  nitrogen  (N)  1-10.  Animal  fats  contain  the  same  elements, 
and  animal  tissues  the  same  with  much  nitrogen. 

In  dried  wood,  the  C,  H,  0  are  atomically  in  the  proportions  nearly 
C6H904.  In  decay,  the  oxygen  used  may  be  that  of  the  wood,  or  of  the 
atmosphere  or  other  substances.  The  C  may  combine  with  0  and  make 
carbon  protoxide,  CO,  the  gas  which  burns  with  a  blue  flame  in  a  furnace ; 
but  it  generally  combines  with  2  0,  making  the  more  stable  and  incom- 
bustible compound  C02,  or  carbonic  dioxide  (carbonic  acid).  The  H  may 
unite  with  O  and  form  water,  H20.  But  instead  of  all  the  C  combining 


124  DYNAMICAL   GEOLOGY. 

with  0,  part,  especially  when  the  decomposition  goes  on  under  water,  or 
where  atmospheric  oxygen  is  excluded,  may  combine  with  H  and  produce 
the  hydrocarbon  CH4  —  called  marsh-gas,  because  sometimes  bubbling  up 
through  marsh  waters  ;  it  is  the  gas  which  burns  and  makes  the  flame  of  a 
wood  fire.  Other  related  hydrocarbons  also  might  form.  But  the  burning 
of  this  gas  when  complete  ends  in  producing  C02  and  H20.  This  is  the  final 
result  when  plants  decompose  in  the  air,  except  minor  results  from  the 
nitrogen  (N)  and  sulphur  (S)  present,  among  which  are  making,  with 
the  nitrogen,  ammonia,  NH3;  and,  with  oxygen,  nitrous  acid  (N203),  and 
nitric  acid  (N205)  ;  and  making,  with  the  sulphur,  hydrogen  sulphide  (sul- 
phuretted hydrogen)  H2S,  and  with  oxygen,  sulphurous  acid  (S02)  and 
sulphuric  acid  (S03). 

In  smothered  combustion  (as  in  making  charcoal  by  burning  wood  under  a  cover  of 
earth),  nearly  all  the  H  and  0  disappear  as  CO,  CO2,  and  H20,  without  a  consumption 
of  all  the  carbon  ;  and  this  happens  when  plants  decompose  under  a  complete  covering  of 
water,  or  earth,  because  this  excludes  the  air  and  confines  the  changes  to  the  elements  of 
the  plants ;  and  the  more  complete  the  protection,  the  greater  will  be  the  proportion  saved 
of  carbon  and  hydrogen,  the  combustible  elements  for  the  making  of  coal.  With  reference 
to  the  making  of  mineral  oil  or  gas,  it  is  to  be  noted  that  if  the  outside  air  is  wholly 
excluded  through  overlying  fine  sediments,  they  may  be  produced  by  the  direct  decomposi- 
tion of  woody  tissues  or  of  animal  oils.  Thus,  if  the  carbon  of  the  wood  (C6H904  nearly) 
combines  with  all  the  oxygen,  making  thereby  2  CO2 ,  it  will  leave  C^g ,  and  2  C4H9  =  C8Hi8 , 
which  is  the  composition  of  some  mineral  oil.  So  in  animal  oils,  as  oleic  acid,  CigH3402 , 
on  separating  C02 ,  there  would  be  left  Ci7H34,  one  of  the  ethylene  oils  ;  or  from  margaric 
acid,  Ci7H3402 ,  the  product  would  be  Ci6H34 ,  or  a  combination  of  marsh-gas  oils.  Fossil 
fishes  are  often  numerous  in  coaly  beds  that  afford  much  oil.  (D.,  Min.,  1868,  p.  726.) 

In  the  change  to  ordinary  bituminous  coal  the  loss  in  the  hydrogen  of  the  wood, 
proportionally  to  that  of  the  carbon,  is  about  two  fifths,  and  that  of  the  oxygen  about 
four  fifths  —  about  5-5  per  cent  of  such  coal  (ash  excluded)  being  hydrogen,  and  12  to  15 
per  cent  oxygen,  with  80  to  81  per  cent  carbon. 

The  carbonaceous  products  from  the  decomposition  of  plants  and  animals 
give  the  black  color  to  soils.  In  wet  soil,  other  acid  products  sometimes 
form,  called  humus  acids,  from  the  Latin  humus,  soil,  or  earth. 

The  returning  to  the  air  of  the  constituents  of  a  plant,  by  decay,  in  the  form  of 
carbonic  acid  and  water,  is  restoring  what  was  taken  and  used  in  the  growth  of  the  plant 
and  balancing  the  account.  The  storing  of  part  of  the  carbon  and  hydrogen  in  the 
rocks  in  the  form  of  coal  and  mineral  oil  and  gas  was  an  abstraction  of  carbonic  acid  from 
the  air,  and  commenced  a  debit  account  which  use  in  combustion  by  man  is  doing  only  a 
little  in  the  way  of  settling.  Happily  the  world  is  better  off  for  the  purification  of  its 
atmosphere. 

3.  Deoxidation,  or  the  abstraction  of  oxygen  from  a  compound  by  any  oxi- 
dizing substance  at  hand.  —  Most  deoxidation  in  nature  is  done  by  organic 
substances  through  the  process  of  decay  above  described.  The  affinity  in  the 
carbon  and  hydrogen  of  the  plant  for  oxygen  is  so  strong  that  it  will  take  it 
away  from  iron  oxides  or  salts,  and  many  other  kinds.  It  may  take  0  from 
Fe203  and  reduce  it  to  FeO ;  so  that  if  there  is  then  an  acid  at  hand  for  com- 


CHEMICAL   WORK.  125 

bination,  as  carbonic  acid,  it  may  take  the  FeO  and  make  iron  carbonate.  Or 
if  the  acid  is  a  humus  acid,  this  acid  may  combine  with  the  FeO,  and,  as  such 
a  compound  is  soluble,  the  waters  may  carry  it  to  the  marshes  for  deposition 
and  re-oxidation. 

Since  the  compounds  so  made  are  colorless  or  nearly  so,  fragments  of  a 
plant  in  a  rock  may  whiten  the  rock  around  them,  thus  making  blotches  in 
red  sandstones,  or  a  zone  may  be  bleached  around  stems  and  roots.  Also, 
the  soaking  down  of  soil  waters  may  make  a  whitish  streak  along  the  top 
of  the  less  permeable  layers. 

In  like  manner  iron  sulphate  or  copperas,  FeO.S03.7aq  (which  oxidation  of  FeS2 
often  produces,  as  above  explained),  may  be  deoxidized  and  reduced  to  FeS2  ;  that  is,  either 
pyrite  or  marcasite.  Fossil  wood  may  be  replaced  by  pyrite  or  marcasite  as  decomposition 
goes  on,  and  shells  may  be  changed  in  like  manner,  as  acid  waters  at  hand  dissolve  and 
remove  the  calcareous  material. 

Calcium  sulphate,  or  gypsum,  is,  by  similar  deoxidation,  converted  into  calcium  sul- 
phide, CaS  ;  zinc  sulphate,  into  zinc  sulphide,  ZnS,  the  mineral,  sphalerite ;  and  lead 
sulphate,  into  lead  sulphide,  PbS,  which  is  the  common  lead  ore,  galena.  After  the  deox- 
idation of  a  sulphate,  as  gypsum  (calcium  sulphate),  to  calcium  sulphide,  the  re-oxidation 
of  the  sulphide  may  take  place,  and  hydrogen  sulphide  (sulphuretted  hydrogen)  may  result 
through  the  agency  of  the  water  at  hand,  thus  :  Ca  takes  oxygen  from  the  water,  making 
CaO,  or  lime  (which  may  combine  at  once  with  CO2  to  make  CaO.C02,  or  calcium  carbo- 
nate), and  the  sulphur,  S,  takes  the  hydrogen  thus  set  free  from  the  water,  making  SH2 , 
or  hydrogen  sulphide  (sulphuretted  hydrogen)  ;  for  CaS  +  H20  =  CaO  +  H2S.  This  is  the 
ordinary  process  by  which  the  gas  of  sulphur  springs  is  made,  as  for  example  those  of 
western  New  York  and  Virginia. 

By  the  oxidation  of  the  hydrogen  of  the  hydrogen  sulphide  making  H20,  or  water,  tne 
sulphur,  S,  becomes  deposited.  This  is  a  very  prominent  source  of  sulphur;  and  ii 
accounts  for  its  frequent  association  with  gypsum  and  limestone. 

Further,  hydrogen  sulphide,  SH2  (sulphuretted  hydrogen),  by  action  on  zinc  sulphate, 
will  deoxidize  the  sulphate  and  make  zinc  sulphide ;  on  iron  sulphate,  it  will  make  an  iron 
sulphide  ;  on  lead  sulphate,  lead  sulphide. 

But  under  warm  and  moist  conditions  the  sulphur  may  oxidize  and  make  sulphuric  acid, 
S03+water;  and  some  sulphuric  acid  springs  in  New  York  have  this  source.  Gypsum 
may  be  formed  by  such  waters  if  limestone  is  within  their  reach.  Pfaff  states  that  at 
depths  in  water  under  a  pressure  of  40  atmospheres  anhydrite  will  probably  form,  and  not 
gypsum.  Anhydrite  is  gypsum  minus  the  water. 

It  may  be  added  that  sulphurous  acid,  S02 ,  is  formed  by  the  combustion  of  sulphur 
(as  in  volcanoes)  ;  and  when  this  gas  comes  into  contact  with  hydrogen  sulphide  (SH2), 
the  sulphur  of  both  is  deposited,  the  oxygen  and  hydrogen  combining  to  form  water ;  and 
this  is  one  source  of  the  sulphur  about  volcanoes. 

With  heat,  carbon  deoxidizes  iron  oxide  and  oxides  of  other  metals,  producing  the 
pure  metal. 

4.  Destructive  effects.  —  Since  nine  tenths  of  rocks  not  limestones  contain 
one  or  more  of  the  common  iron-bearing  silicates,  pyroxene,  hornblende  (or 
other  species  of  the  hornblende  family),  or  black  mica,  and  almost  all  rocks 
have  a  sprinkling  of  pyrite  or  marcasite,  the  oxidation  process  is  all-pervading 
in  its  destruction.  The  presence  of  water  and  air  being  necessary,  the  more 
porous  the  rock,  the  deeper  and  more  rapid  the  decay.  The  rocks  where  the 


126 


DYNAMICAL   GEOLOGY. 


destructible  mineral  is  a  chief  constituent  become  covered  with,  a  rusty  crust 
which  is  ever  encroaching  inward;  and  this  crust  is  slowly  reduced  to  a 
rusty  earth,  having  parted  with  all  soluble  ingredients  ;  or,  losing  the  rusting 
mineral,  it  finally  falls  to  earth  or  sand.  A  porous  granite  or  gneiss  contain- 
ing black  mica  may  become  deeply  rusted,  and  finally  reduced  to  a  weak  mass 
of  quartz  and  unaltered  feldspar,  —  good  material  for  a  granitic  sandstone. 

If  marcasite  or  pyrite  is  present  in  any  rock,  there  is  not  only  oxidation, 
but  corrosion  from  the  sulphuric  acid  that  may  be  formed,  which  attacks  any 
lime  present  in  the  minerals  of  the  rock,  or  any  magnesia,  or  potash,  or  soda, 
or  alumina,  and  makes  sulphates  with  each.  The  aluminum  sulphates  are 
alums,  but  strictly  so  only  when  potash,  soda,  or  some  other  base  is  also 
present.  Some  beds  of  shale  containing  iron  sulphide  are  impregnated  or 
interlaminated  with  alum  which  has  been  thereby  made,  the  shale  affording 
the  alumina  of  the  alum. 

Limestones,  even  the  whitest  of  marbles,  often  contain  a  trace  of  iron 
or  of  manganese  in  combination,  and  occasionally  masses  of  the  iron  car- 
bonate, siderite.  The  iron  carbonate,  unless  in  a  massive  state,  readily 
oxidizes  ;  and  so  also  does  the  iron  of  the  limestone  on  exposure  for  a  few 
months ;  and  this  is  a  commencement  of  the  change  in  the  whole  mass  to 
limonite.  The  work  in  progress  is  illustrated  by  Fig.  132,  representing  an 


132. 


133. 


Impure  limestone  decaying  to  limonite. 


Same,  with  calciferous  schist.    D. 


impure  ferriferous  limestone  as  it  appears  where  the  alteration  is  going 
on  at  the  Amenia  Ore-pit,  IST.Y.,  southwest  of  Salisbury,  Conn. ;  and  Fig. 
133,  the  same,  with  the  calciferous  schist  adjoining  also  changing.  If  one 
per  cent  of  iron  is  present,  a  limestone  will  rust  and  decay ;  if  as  much  man- 
ganese is  present,  it  will  become  covered  with  black  stains.  f  The  massive 
siderite  changes  slowly  over  the  surface  and  in  rifts. 

Limonite  —  the  yellow-brown  oxide  of  iron,  or  yellow  ocher  —  is  the  most 
common  result  of  the  oxidation;  but  hematite,  of  red-ocher  color,  is  often 
produced  in  warm  and  rather  dry  climates.  Nearly  all  red,  yellow,  and 
brown  rocks,  sand-beds,  or  earth-beds,  owe  their  color  to  iron  in  one  of 
these  two  forms. 

Oxidation  of  the  iron  in  pyroxene  gives  the  yellow-brown  fronts  to  trap 
bluffs  —  not  their  gray  and  black  tints,  which  are  due  to  lichens ;  and  has 
spread  delicate  surface  shades  of  red  and  yellow  over  sandstones  in  the 
Yellowstone  Park,  and  other  dry  parts  of  the  Rocky  Mountains,  through 
the  oxidation  of  the  little  iron  inside. 


CHEMICAL   WORK.  127 

This  oxidation  process,  and  other  methods  of  decay,  go  on  with  greatest 
rapidity  in  the  fissures  of  rocks,  below  a  surface  of  soil,  because  the  descend- 
ing surface  waters  keep  them  almost  continuously 
wet ;  and  it  is  under  such  circumstances  that  a  rock 
which  is  much  fissured  or  jointed  becomes  re- 
duced to  a  pile  of  great  bowlders  with  rusty  earth 
between,  as  illustrated  in  the  figure  annexed.  The 
balls  of  rock  here  represented  are  very  common  in 
decomposing  rocks  from  granites  and  trap  to  sand- 
stones. They  are  simply  a  result  of  surface  decay 
along  the  many  planes  of  fracture  (Fig.  134).  The 
decay  or  oxidation  at  first  produces  a  thin  discolor- 
ing of  adjoining  surfaces,  as  in  the  lower  part  of 

the  figure;  and  this  continues,  eating  off  the  angles,  which  are  attacked  from 
three  directions,  until  a  bluif  of  solid  rock  becomes  apparently  a  pile  of  great 
bowlders.  With  the  progress  of  the  alteration,  the  discolored  portion 
becomes  banded  with  yellow  and  brown ;  and  as  it  deepens,  the  outer  part 
of  the  spheroid  sometimes  separates  in  concentric  shells,  precisely  corre- 
sponding with  the  concentric  structure  of  a  concretion.  But  these  concentric 
shells  are  due  to  the  decay  that  is  in  progress  ;  and  apparently  to  alternations 
in  the  work  of  decay  dependent  on  climate  and  the  capillary  action  above 
explained.  Bounded  stones  or  bowlders  are  very  often  so  made.  After 
separation  from  the  pile,  and  therefore  from  exposure  to  almost  permanent 
moisture,  the  masses  may  decompose  outside  with  extreme  slowness. 

5.  Constructive  effects.  — As  the  process  is  a  means  of  reducing  the  hardest 
rocks  to  earth  and  sand,  it  aids  in  preparing  material  for  new  rock-making, 
and  also  in  supplying  earth  and  sand  for  soil  and  fertility.  Without  it,  and 
one  other  associated  process  mentioned  beyond,  the  earth  would  have  had 
very  scanty  geological  records  and  only  low-grade  life. 

This  agency  has  produced,  or  aided  in  producing,  a  large  part  of  the  great 
and  valuable  iron  ore  beds  of  the  world's  history,  from  Archaean  time  onward. 
The  limonite  ore  beds  (often  called  by  miners  "  hematite  "  beds)  are  among 
the  products.  They  occur  of  great  size  and  value  in  West  Stockbridge, 
Mass.,  Salisbury,  Conn.,  Amenia  and  elsewhere  in  New  York,  in  eastern 
Pennsylvania,  western  Virginia,  and  farther  south  to  Alabama,  as  a  result  of 
the  oxidation  chiefly  of  a  ferriferous  limestone,  and  of  any  iron  carbonate 
the  limestone  may  contain.  In  the  formation  of  the  iron  oxide,  carbonic 
acid  is  set  free,  and  the  weakened  calcareous  rock  is  hence  readily  removed 
by  percolating  waters ;  hence  great  cavities  are  made  by  the  process,  ready  to 
receive  the  ore  as  it  is  produced.  Any  slates  or  schists  adjoining  are  also 
destroyed  by  the  action. 

Iron  sulphides  have  been  the  source  of  similar  beds,  but  such  ore  is 
likely  to  contain  some  sulphur.  The  Amenia  ore  bed  is  a  good  place  for 
studying  the  formation  of  the  ore  from  both  a  ferriferous  limestone  and 
a  massive  iron  carbonate.  These  ore-beds,  although  superficial,  cannot  be 


128  DYNAMICAL   GEOLOGY. 

affirmed  to  be  modern ;  for  they  have  probably  been  in  progress  ever  since 
the  land  first  emerged  from  the  ocean  so  that  air  and  water  could  begin  the 
work. 

In  the  destruction  of  the  iron-bearing  minerals  of  surface  rocks,  the  iron 
oxide  combined  with  a  humus  acid  is  often  carried  into  marshes  to  make 
"  bog  iron  ores."  The  ores  thus  formed  have  much  value,  although  likely 
to  contain  phosphates  as  impurity,  because  of  the  animal  and  vegetable  mat- 
ters that  live  and  die,  or  find  burial,  in  swamps. 

The  consolidation  of  beds  of  sand  and  gravel,  or  layers  of  rock,  is  another 
of  the  constructive  effects  of  the  iron  oxide  that  is  distributed  through  the 
material  of  the  beds.  In  the  simplest  form  of  it,  the  waters,  filtering 
through  soil  and  gravel,  take  up  enough  oxide  of  iron  to  cement  a  bed  of 
pebbles  lying  at  a  lower  level  on  another  layer  sufficiently  close  in  texture 
to  hold  the  water  and  give  the  iron  a  chance  to  deposit;  and  this  is  one 
way  in  which  what  is  called  hard-pan  is  sometimes  made.  The  underlying 
impervious  bed  is  not  absolutely  necessary  to  the  result,  although  promoting 
it.  The  pebbles  wet  with  the  ferruginous  waters,  when  they  dry  in  times 
of  drought,  take  a  deposit  of  iron ;  and  this  process  may  end  in  complete 
consolidation.  In  other  cases  the  oxide  is  produced  throughout  the  deposit 
under  the  action  of  infiltrating  waters,  and  slowly  becomes  a  cement  as  it 
solidifies. 

This  mode  of  consolidation  without  aid  of  heat  is  not  the  most  common 
nor  the  most  efficient. 

The  beds  of  sulphur  of  the  world  have  been  made  by  the  two  processes 
mentioned  on  page  125,  and  chiefly  the  former. 

HYDRATION,  OR  THE  CHEMICAL  ABSORPTION  OF  WATER. 

Many  minerals  take  up  water  on  "weathering."  But  this  usually  is 
an  accompaniment  of  commencing  decomposition.  An  example  of  simple 
hydration  of  geological  importance  is  the  change  of  anhydrite  (CaO.S03)  to 
gypsum  (CaO.S03.2H20).  As  the  minerals  are  very  unlike  in  cleavage,  and 
both  occur  in  large  beds,  the  change  is  strikingly  noticeable. 

CARBONIC  ACID,  HUMUS  ACIDS. 

1.  General  action.  —  Carbonic  acid  (C02)  is  ever  present  in  the  atmos- 
phere, of  which  it  constitutes  3  parts  in  10,000  by  volume,  and  in  all  rain 
water,  river  water,  and  sea  water.  It  is  often  given  off  by  mineral  springs, 
and  occasionally  escapes  in  large  volumes  from  fissures  in  volcanic  regions. 
In  the  northeast  corner  of  Yellowstone  Park  is  "  Death  Gulch,"  where  the 
gas  rises  freely  from  the  waters  of  Cache  Creek,  to  the  destruction  of  bears 
and  other  wild  animals.  Butterflies  and  other  insects,  besides  skeletons  of 
bears,  elk,  squirrels,  etc.,  attest  to  its  deadly  character  (W.  H.  Weed,  1889). 
Death's  Valley  in  Asia  Minor,  and  the  Dog's  Grotto  at  the  Solfatara  near 
Naples,  are  other  localities  of  escaping  carbonic  acid. 


CHEMICAL   WORK.  129 

Carbonic  acid  is  given  out  in  respiration,  and  is  a  product  of  animal  and 
vegetable  decay ;  and  by  this  means  it  becomes  distributed  through  the  air 
and  waters.  The  humus  acids,  ampng  the  results  of  vegetable  and  animal 
decay  by  oxidation,  occur  in  all  damp  soils  in  which  such  decay  is  going 
on.  The  action  of  these  acids  has  been  studied  by  A.  A.  Juiien.1  They 
are  effective  especially  through  tueir  affinity  for  iron  protoxide,  magnesia, 
lime,  soda,  potash,  and  some  other  protoxide  bases. 

a.  In  water,  carbonic  acid  takes  up  calcium  carbonates  from  any  calcareous  material, 
whether  in  the  state  of  limestone,  or  in  other  conditions,  to  make  calcium  bicarbonate 
for  transportation.     On  evaporation,  the  bicarbonate  again  becomes  calcium  carbonate. 
The  amount  taken  up  is  increased  by  the  presence  of  magnesium  or  sodium  sulphate  in  the 
waters  (Hunt).     The  Mammoth  Hot  Springs  contain  0-6254  parts  of  calcium  carbonate 
in  1000  of  water,  which  is  over  4  times  as  much  as  pure  water  saturated  with  carbonic  acid 
will  take  up  (Russell). 

b.  It  takes  the  bases  —  potash,  soda,  lime  —  out  of  a  feldspar,  thus  destroying  the 
mineral  to  as  great  a  depth  in  a  rock  as  the  carbonated  water  and  air  can  penetrate, 
and  reduces  it  to  clay.    This  is  true  especially  of  the  potash-feldspars,  orthoclase,  and 
microcline.     The  same  work  is  done  by  the  humus  acids.     The  clay  results  thus :  Ortho- 
clase consists  of  silica,  alumina,  and  potash.     In  the  change  it  loses  the  potash  and  part  of 
the  silica,  and  becomes  silica,  alumina,  and  water.     Thus  the  compound,  K20.  A1203  .Si60i2 , 
becomes  H2O.Al203.Si204,  and  1  of  water.     Half  of  the  water  (H20)  received  replaces 
the  potash  (K20)  lost. 

c.  Carbonic  acid  decomposes  other  minerals  in  a  similar  way,  taking  out  the  protoxide 
bases.     It  may  thus  form  a  soluble  iron  bicarbonate  in  waters,  which  streamlets  may 
convey  to  marshes.     But  only  a  trace  of  this  iron  salt  can  be  held  in  waters  under  the 
existing  atmospheric  pressure.     The  humus  acids  also  make,  with  iron,  soluble  salts,  and 
do,  at  present,  the  chief  part  of  such  transportation  for  the  making  of  bog  ores.     On  the 
evaporation  of  the  solvent  waters,  the  iron  in  each  case  is  usually  deposited  as  hydrous 
sesquioxide  or  limonite. 

d.  Further :  it  is  supposed  that  carbonic  and  humus  acids  may  aid  in  the  oxidation 
of  the  protoxide-iron  of  a  mineral  by  bringing  it  to  the  surface  of  a  mass  of  porous  rocks, 
so  as  to  make  the  oxidation  possible. 

2.  Destructive  effects.  —  For  the  reasons  stated  carbonated  water  con- 
taining humus  acids  has  done  a  vast  amount  of  eroding  work. 

(a)  Draining  out  by  infiltrating  waters.  —  The  lightest  work  is  the  drain- 
ing of  any  soluble  ingredient  out  of  a  rock.  Calcareous  grains  are  thus 
drained  from  a  porous  calcareous  sandstone,  or  quartzyte,  increasing  its 
porosity.  So  also  calcareous  fossils  are  removed  from  rocks  that  admit  infil- 
trating waters,  leaving  the  rock  cellular.  When  a  crystalline  limestone  or 
marble,  a  porous  rock,  consists  of  dolomite,  but  contains  mixed  calcite,  all 
the  calcite  grains  are  drained  out  because  they  are  the  most  soluble,  and 
the  rest  are  left  to  fall  to  loose  sand,  an  effect  exemplified  in  many  places 
over  Canaan,  Conn.,  and  Berkshire  County,  Mass.  If  the  fossils  of  a  lime- 
stone are  made  of  calcite  and  aragonite  (the  latter  the  prismatic  calcium 
carbonate),  the  aragonite  portion  is  taken  away  —  a  fact  first  reported  by 
Sorby.  Shells  of  the  kind  referred  to  are  those  of  the  genera  Pinna,  Mytilus, 

1  On  the  reaction  of  the  humus  acids  see  A.  A.  Julien,  Rep.  Amer.  Assoc.,  1879. 
DANA'S  MANUAL  —  9 


130 


DYNAMICAL   GEOLOGY. 


Spondylus,  Patella,  Fusus,  Purpura,  and  Littorina,  in  which  the  inner  pearly 
layer  is  aragonite,  and  the  outer  calcite.  The  shells  of  most  Gastropods 
and  of  Cephalopods  are  aragonite ;  and  Corals,  including  the  Millepores,  are 
mainly  so ;  while  shells  of  Khizopods,  Echinoderms,  and  Brachiopods  consist 
of  calcite. 

Further,  if  the  limestone  contains  iron  or  manganese  combined  with  the 
calcite,  carbonated  water  will  bring  the  iron  to  the  surface,  or  the  iron  car- 
bonate, or  the  manganese,  for  oxidation,  weakening  and  discoloring  the  rock. 
The  action  on  feldspar,  above  mentioned,  is  a  common  means  of  destruction 
in  the  case  of  granites  and  related  rocks. 

(b)  Process  of  draining  limited.  — -But  it  is  also  to  be  observed  that  these 
effects  occur  only  so  far  as  the  rocks  are  porous.     The  fossils  of  compact 
argillaceous  sandstones  and  shales — common  kinds  of  fossiliferous  rocks 
and  some  dating  from  the  Cambrian  —  are  seldom  drained  out  or  injured 
at  all  by  infiltrating  waters,  except  when  near  the  surface.     The  iron  and 
manganese  taken  out  of  some  crystalline  limestones  are  removed  only  for  a 
short  distance  inward ;   but  the  process  destroys  the  limestone  as  it  eats  in, 
and  is  thus  enabled  to  erode  farther.     Deep  below  the  surface  the  same  rocks 
are  solid  and  not  discolored.     All  deep-water  rocks  are  moist,  but  the  moist- 
ure is  ordinarily  stationary  unless  a  surface  drought  reaches  downward,  or 
an  invasion  of  heat  comes  upward  from  below,  when  the  moisture  thus  lost 
may  be  later  replaced.     Even  beds  of  salt  in  subterranean  rocks  are  not 
dissolved  away. 

(c)  Surface  erosion.  —  Waters  containing  carbonic  acid  or  hurnus  acids 
eat  away  the  surface  of  solid  limestone,  fluting  precipices,  widening  crevices, 
excavating  caverns.     They  often  leave  calcareous  fossils  projecting  slightly 
above  the  surface,  and  develop  with  great  perfection  silicified  kinds.     The 
length  of  the  caverns  thus  made  in  the  Carboniferous  limestone  of  Kentucky, 


Making  of  caverns  in  limestone.     Shaler. 

a  rock  200  to  1000  feet  thick,  is  estimated  by  N.  S.  Shaler  to  amount  to 
100,000  miles.  The  work  is  begun  by  the  descent  of  waters  along  joints 
in  the  rock,  whenever  there  is  a  chance  for  discharge  below,  by  running 
down  or  trickling  along  between  layers  of  the  limestone.  The  process  and 
result  are  illustrated  in  the  above  figure  by  Shaler.  In  the  movement  of  the 
waters,  the  fissure  or  joint  (B)  becomes  enlarged  to  a  "sink-hole,"  and  exca- 
vation begins  between  the  layers.  The  end  is  a  great  cave,  having,  it  may 


CHEMICAL  WORK.  131 

be,  its  spacious  chambers,  high  water-falls,  and  free-flowing  rivers.  The 
flowing  waters  sometimes  work  also  by  abrasion ;  but  there  is  usually  little 
loose  material  to  transport  for  the  purpose  of  abrasion. 

In  a  similar  way  limestone  cliffs  have  been  chiseled  into  ranges  of 
turrets,  and  deep  recesses  and  channels  made  for  rivers  through  lime- 
stone strata. 

The  excavation  of  the  lagoon  basins  of  coral  islands  has  been  attributed 
erroneously  to  erosion  by  the  carbonic  acid  of  the  sea  water. 

(d)  Except  for  surface  erosion,  limestone  consisting  of  pure  calcite,  free 
from  iron  sulphides,  is  a  durable  rock,  whether  uncrystalline  or  crystalline, 
as  in  the  case  of  the  Carrara  marble,  of  which  such  marvelous  structures  as 
the  Milan  cathedral  have  been  made.     But  a  magnesian  limestone  or  dolo- 
myte,  when  crystalline,  is  often  easily  destructible,  because,  as  already  stated, 
the  porous  rock  is  likely  to  contain  disseminated  calcite ;   and  as  this  is 
more  soluble  than  dolomyte,  percolating  waters  carry  it  off,  leaving  the  rest 
in  the  state  of  sand  —  a  bad  condition  for  the  marble  temple  that  may  be 
made  of  it.     The  presence  of  the  calcite  can  be  detected  only  by  observing 
whether,  at   any   exposure   of   a  layer   in   the   region   of   a   quarry,  it   is 
turning  to  sand. 

Polished  limestone  marble  containing  any  chert  or  other  hard  mineral, 
if  employed  in  out-door  ornamentation  or  on  monuments,  is  sure  to  weather 
rough  and  become  unsightly,  and  the  chert  may  be  made  to  stand  out  in 
ragged  points  or  knobs.  Even  the  vertical  movement  of  the  atmosphere 
over  polished  marbles  will  in  time  take  off  or  dim  the  polish. 

(e)  Since  carbonic  acid  attacks  feldspar  as  well  as  other  minerals,  this 
agency,  and  that  of  oxidation,  leave  scarcely  any  kind  of  rock  safe  against 
destruction.      Those   are   safest    that   are   free   from   iron   sulphides,   and 
especially  those   that  are  so  fine-grained  and  compact   that  water  cannot 
gain  access.     Hence,  the  method  of  testing  rocks  for  porosity  by  ascertaining 
how  much  water  they  will  absorb  in  24  hours  is  excellent.      Some  slate 
rocks  are  very  durable  because  of  their  fine  grain  and  the  absence  of  any 
soluble  minerals.     Some  granites  absorb  little  water,  some  very  much ;  and 
the  latter  are  easily  destructible. 

3.  Constructive  effects.  —  (a)  Calcareous  deposits.  —  The  most  familiar 
deposits  of  this  kind  are  the  stalactites  and  stalagmites  of  caverns,  dripstone 
formations ;  so-called  because  made  by  the  calcareous  waters  dropping  from 
the  roofs.  The  "Gibraltar  rock"  is  stalagmite.  Still  more  interesting  are 
the  travertine  or  tufa  deposits  of  streams.  Leaves,  nuts,  and  stems  are  often 
petrified  by  calcareous  waters. 

The  travertine  of  Tivoli,  near  Rome,  constitutes  a  large  deposit  along  the 
Anio,  whose  waters  are  there  strongly  calcareous.  Along  Gardiners  Kiver, 
in  the  region  of  the  Yellowstone  Park,  thick  limestone  deposits  have  been 
made,  as  is  well  illustrated  and  described  in  the  Reports  of  Hayden's 
Geological  Survey  of  the  Territories.  The  calcareous  waters,  in  descend- 
ing the  slopes  of  the  hills,  have  made  a  series  of  parapets  at  different 


132 


DYNAMICAL   GEOLOGY. 


levels,  inclosing  basins,  over  which  the  water  drips  or  plunges  on  its  way 
to  the  bottom,  as  illustrated  in  Fig.  136.  Travertine  is  usually  somewhat 
cellular  and  concretionary  in  structure  if  not  in  exterior  forms,  unlike  the 
even-grained  material  of  ordinary  limestone. 


136. 


Calcareous  formations.     Mammoth  Hot  Springs,  Gardiners  River.     Phot,  by  Jackson. 

About  the  lakes  of  the  Great  Basin  calcareous  deposits  have  unusual 
extent  and  variety  of  forms,  rising  often  into  groups  of  rounded  columns, 

137. 


Tufa  deposits,  Lake  Mono.      I.  C.  Russell. 


towers,  domes,  and  other  shapes.  One  example,  taken  from  I.  C.  Russell's 
Report  on  Lake  Mono  (1889),  is  illustrated  in  Fig.  137.  These  deposits 
are  also  abundant  in  other  parts  of  the  Basin. 


CHEMICAL   WOKK. 


133 


Some  of  the  travertine  deposits  of  Gardiners  Eiver  and  elsewhere  are  a 
result  of  the  growth  and  secretions  of  Conferva-like  plants,  as  explained  bv 
W.  H.  Weed. 

In  the  Lahontan  and  138. 

Mono  basins,  as  described 
by  King  and  later  by 
Eussell,  he  material  has 
often  a  crystalline  form, 
the  origin  of  which  is 
yet  unexplained  :  this 
variety  is  the  tliinolite 
of  King.  A  common 
form  is  represented  in 
Fig.  138. 

The  beautiful  trans- 
lucent limestone  of  Te- 
cali,   Mexico,    often 
wrongly  called  onyx,  because  banded  in  colors  when  polished,  is  a  calcareous 
deposit  failing  of  the  coarse  and  irregular  grain  of  travertine. 

(b)  Consolidation.  —  Of  still  greater  geological  range  is  the  cementing 
work  done  by  calcareous  waters.  Ordinary  sea  water,  especially  where 
shells  and  corals  abound,  consolidates  sands  made  from  coral  and  shell  into 
limestone.  The  beach  sands,  drifted  sands,  and  sands  over  the  reefs,  when 
drying  from  exposure  to  the  air,  become  cemented  in  this  way.  Conglom- 
erates are  also  made  of  broken  corals,  shells,  and  calcareous  or  other  pebbles, 
and  breccias,  in  this,  as  in  other  ages,  out  of  a  talus  or  any  accumulation  of 
limestone  blocks. 

The  under-water  calcareous  sands,  as  those  about  coral  reefs,  also  become 
cemented  by  the  same  means,  but  into  a  compact  limestone  like  ordinary 
limestones,  showing  usually  no  sand-like  grains  in  the  texture. 


Thinolite :  from  Lake  Mono.    I.  C.  Russell. 


(c)  Dolomyte-making.  —  Even  dolomyte,  (sCaJMg)  03C,  owes  its  origin  at 
times  —  if  not  always  —  to  the  conditions  that  exist  in  the  history  of  coral 
reefs  when  the  magnesia,  required  to  make  the  calcareous  grains  magnesian, 
could  have  had  no  source  but  the  ocean.  One  case  of  the  kind  is  reported 
by  the  author  (1849)  from  the  island  of  Metia,  an  elevated  atoll  north  of 
Tahiti  (Corals  and  Coral  Islands,  page  393).  The  rock  is  a  compact  white 
limestone.  An  analysis  by  B.  Silliman  proved  that  it  contained  38-07  per 
cent  of  magnesium  carbonate,  the  rest  being  calcium  carbonate.  The  very 
fine  texture  of  the  rock  indicates  that  it  was  made  of  the  finest  of  calcareous 
ooze  or  mud,  such  as  forms  through  gentle  wave-action  in  shallow  lagoons  ; 
and  in  such  lagoons,  mainly  shut  off  from  the  sea,  and  therefore  in  a 
"salt-pan"  condition  (page  120),  the  concentrated  brines  contained  the 
magnesium  chloride  and  sulphate  in  a  state  that  favored  the  formation  of 
dolomyte. 


134  DYNAMICAL  GEOLOGY. 

The  change,  if  produced  through  the  magnesium  chloride  (MgCl),  required  the  removal 
of  £  Ca  by  the  chlorine  of  an  equivalent  amount  of  Mg.  If  this  is  the  true  theory  of  dolo- 
myte-making,  then  great  shallow  areas  or  basins  of  salt-pan  character  must  have  existed 
in  past  time  over  various  parts  of  the  continental  area  and  have  been  a  result  of  the  oscilla- 
tions of  the  water  level.  Such  magnesian  limestones  contain  few  fossils,  partly  because  of 
the  fine  trituration,  and  partly,  no  doubt,  because  of  the  unusually  briny  condition  of  the 
waters.  The  frequent  alternation  of  calcite  and  dolomyte  strata  would  indicate  alternations 
between  the  clear-water  and  salt-pan  conditions.  Dolomization,  in  the  case  of  such  beds, 
has  often  taken  place  after  partial  or  complete  consolidation ;  for  many  dolomytes  are 
exceedingly  porous,  because  of  the  diminished  bulk  of  the  dolomyte  —  one  eighth  to  one 
tenth.  T.  S.  Hunt  made  the  porosity  of  several  Canadian  Lower  Silurian  dolomytes,  10 
to  13^  per  cent  (1866). 

Local  cases  of  alteration  are  well  known.  Adolf  Schmidt  mentions  such  at  the  lead 
mines  of  Missouri,  which  he  attributes  (following  Bischof)  to  the  action  of  magnesium 
bicarbonate. 

In  a  memoir  on  the  famous  dolomyte  region  of  the  Tyrol,  Dolter  and  Homes,  geol- 
ogists of  Vienna,  discuss  this  subject  at  length,  and  reach  the  following  conclusions: 
(1)  Some  large  limestones,  weakly  dolomitic,  may  have  been  made  out  of  those  organic 
secretions  which  contain  a  little  magnesia  ;  (2)  minor  cases  of  the  production  of  dolomyte 
are  due  to  the  alteration  of  limestone  through  the  introduction  of  magnesium  carbonate ; 
but  (3)  the  larger  part  of  dolomyte  formations,  whether  more  or  less  rich  in  magnesia,  have 
been  formed  from  organic  calcareous  secretions  through  the  action  of  the  magnesium  salts 
of  sea  water,  especially  the  chloride. 

(d)  Making  of  day  and  soil. — Pure  white  clay,  or  kaolin,  used  in  mak- 
ing porcelain,  is  sometimes  in  strata  of  wide  extent ;  and  the  common  impure 
river-valley  clays,  employed  in  brick-making  and  coarser  pottery,  have  no 
less  value.     One  of  the  largest  kaolin  beds  in  New  England,  at  New  Marl- 
boro, in  Berkshire  County,  Mass.,  was  probably  made  by  the  decomposition  of 
the  orthoclase  that  was  disseminated  through  quartzyte,  and  its  removal  by 
percolating  waters  to  the  bed  of   a   streamlet;    for  in  other  localities  in 
Berkshire  this  result  is  now  going  on  from  the  same  quartzyte.     The  absence 
of  black  mica  and  other  iron-bearing  minerals  insured  its  being  white. 

(e)  TJie  blanching  of  red  and  rusty  rocks  by  waters  containing  carbonic  acid 
and  organic  acids  or  materials  is  a  common  and  important  effect.     Colored 
clays  are  drained  of  their  iron  oxide  and  whitened  by  percolating  waters.     A 
deeply  rusted  block  of  basalt  or  granite  may  thus  be  made  to  have  a  white 
exterior  an  inch  or  more  deep. 

(/)  Again,  the  impurities  of  a  limestone  are  sometimes  made  available  for 
soil,  by  the  continued  action  of  carbonated  waters,  and  the  removal  thereby  of 
the  calcareous  part.  Shells  and  corals  contain  about  O5  per  cent  of  impurity, 
consisting  chiefly  of  iron  oxide  and  alumina ;  and  the  action  of  the  rains  over 
the  hills  of  coral  sand-rock  on  Bermuda,  through  centuries  past,  has  left  a 
residuum  of  red  earth  which  is  the  soil  of  the  island,  as  Wyville  Thomson 
suggested.  The  red  ooze  or  mud  over  much  of  the  ocean's  bottom  below 
2500  fathoms  is  due  chiefly  to  the  removal,  in  like  manner,  of  the  calcium  car- 
bonate of  the  Globigerinae  and  other  Rhizopods,  in  consequence  of  an  excess 
of  carbonic  acid  in  the  bottom  or  abyssal  waters.  The  life  of  the  sea-bottom 


CHEMICAL   WOKK.  135 

has  no  accompanying  vegetation  to  use  up  the  carbonic  acid  of  respiration 
and  decomposition,  and  this  gas  would  therefore  become  accumulated  in  its 
depressions. 

SILICA:   QUARTZ  AND  OPAL  SILICA. 

Silica  in  solution  does  the  greater  part  of  its  geological  work  when  aided 
by  heat.  Still  much  consolidation  has  been  carried  on  by  cold  solutions, 
especially  solutions  of  alkaline  silicates,  as  potassium  and  sodium  silicates. 
The  former  of  these  silicates  is  the  waterglass  of  the  shops,  K20.  4Si02, 
much  used  for  making  artificial  stone  and  for  other  purposes. 

Waters  percolating  through  beds  of  volcanic  ashes,  by  decomposing  the 
feldspar  present,  take  up  silica  and  deposit  it  in  the  form  of  quartz  and 
opal,  making  silicified  wood  and  the  finest  of  opals.  In  this  way  petrified 
forests  have  been  made.  In  Napa  County,  California,  according  to  the 
descriptions  of  0.  C.  Marsh,  in  1871,  one  of  the  prostrate  trunks  of  the 
silicified  forest,  exposed  to  view  by  the  washing  away  of  the  tufa  and 
tufaceous  sandstone,  was  63  feet  long,  and  7  feet  in  diameter.  In  the  Yel- 
lowstone Park,  according  to  W.  H.  Holmes,  in  his  paper  of  1878,  the  forest 
trunks,  from  one  to  ten  feet  in  diameter,  are  at  several  horizons  in  a  deposit 
of  tufa  5000  feet  thick,  indicating  successive  disastrous  showers  of  volcanic 
ashes,  at  intervals  long  enough  for  the  growth  of  a  great  forest.  In  Arizona, 
near  Carrizo,  in  Apache  County,  there  is  a  noted  locality  which  affords  aga- 
tized  wood  of  great  beauty,  which  has  been  well  named  Chalcedony  Park.  In 
such  cases  heat  from  hot  springs  may  often  have  given  aid ;  but  it  is  probable 
that  the  temperature  in  the  Yellowstone  region  was  only  that  of  the  descend- 
ing volcanic  ashes  and  accompanying  rainfall.  The  decomposition  of  the  out- 
side of  trap  sets  silica  free,  which  coats  the  surface  with  a  whitish  pearly 
layer  of  opal  silica. 

Beds  of  Diatoms  and  other  siliceous  organisms  are  sometimes  converted 
by  percolating  waters  into  opal.  The  siliceous  organisms  that  were  originally 
disseminated  in  the  calcareous  materials  out  of  which  limestones  and  chalk 
were  made  were  the  source  of  the  flint  and  chert,  that  occur  in  these  rocks. 
Siliceous  sponge-spicules  constitute  a  chief  part.  This  was  early  proved  for 
flint,  and  for  Lower  Devonian  and  Lower  Silurian  cherts  ;  but  it  has  been 
proved  to  be  true,  by  Dr.  G.  J.  Hinde,  for  cherts  or  flints  of  all  geological 
ages,  whatever  the  size  of  the  beds. 

The  silicification  of  wood  referred  to  above  is  in  part  due  to  silica  from 
siliceous  organisms. 

The  amount  of  silicification  of  fossils  that  has  taken  place  in  cold  rocks  makes  it 
probable  that  more  consolidation  is  due  to  the  process  than  has  been  supposed.  Cases  of 
the  hardening  of  the  exposed  surface  of  a  sandstone  or  quartzyte,  making  a  hard  crust, 
described  by  M.  E.  Wadsworth  (1883),  have  an  important  bearing  on  the  subject.  He 
speaks  of  a  block  of  white  Potsdam  sandstone,  in  Wisconsin,  which  was  friable  on  the 
protected  side,  but  on  the  side  exposed  to  the  prevailing  storms  was  nearly  a  quartzyte  ; 
and  a  surface  freshly  exposed  by  fractures  was  found,  six  months  later,  to  be  much 


136  DYNAMICAL   GEOLOGY. 

indurated.  The  St.  Peter's  sandstone  afforded  similar  facts.  In  one  case  the  cavities 
over  the  exposed  surface  had  a  lining  of  quartz  crystals,  while  the  rock  a  few  inches 
below  had  the  common  friable  character.  The  effects  were  connected  in  some  way  with 
weathering  processes.  In  some  cases  of  the  kind  the  silica  may  have  come  from  the 
decomposing  action  of  percolating  acid  waters  on  feldspar  grains  sparsely  disseminated 
through  the  rock. 

Over  the  cold  bottom  of  the  ocean  some  silicates  have  been  formed.  Among  them 
are  masses  or  concretions  of  bronzite,  a  silicate  of  magnesia  and  iron  related  to  pyroxene, 
and  small  crystalline  groups  of  Phillipsite  (Christianite).  At  depths  of  2200  fathoms  and 
over,  the  pressure  on  the  bottom  is  5000  to  12,000  pounds  to  the  square  inch ;  and  this 
may  favor  the  production  of  silicates,  where  the  siliceous  parts  of  Sponges,  Diatoms,  or 
Radiolarians  abound,  with  the  results  of  the  decomposition  of  volcanic  dust  and  pumice. 
Another  silicate  of  common  occurrence,  forming  in  shallow  water  as  well  as  in  deep,  is 
the  green-sand  called  glauconite,  a  hydrous  silicate  of  iron  and  potash. 

CHEMICAL  WORK  OF  LIVING  ORGANISMS. 

Respiration  in  animals,  and  also  in  plants,  is  a  means  of  introducing  oxy- 
gen from  the  air  to  carry  on  processes  of  oxidation  among  the  elements  in 
the  structure,  and  the  excretion  of  carbonic  acid  is  one  prime  result.  The 
growth  of  green  plants,  however,  depends  on  a  deoxidation  process,  the  car- 
bonic acid  of  the  air  being  decomposed  in  the  sunlight  by  the  green  color- 
ing-matter (chlorophyll)  of  the  plant,  its  carbon  forming  the  food  of  the 
plant  and  its  oxygen  being  set  free.  Plants  of  the  Fungus  division  (Mush- 
rooms and  the  Microbes)  are  not  green  (have  no  chlorophyll),  and  cannot 
get  their  food  directly  from  the  carbonic  acid  in  the  air.  The  chemical  work 
of  life  of  most  geological  importance,  apart  from  the  making  of  coal  and 
related  products,  is  that  carried  on  by  the  lower  plants ;  and  only  this  is  here 
briefly  considered. 

Plants,  and  especially  the  lower  Cryptogams,  contribute  chemically  to 
geological  change  through  their  roots  or  the  fibers  with  which  they  come 
in  contact  with  rocks.  The  acidity  of  roots  is  often  very  decided,  as  is 
manifest  from  the  furrows  they  make  in  the  surfaces  of  stories,  and  especially 
in  limestones.  Boots  of  plants  germinated  in  sand  over  a  slab  of  marble 
leave  an  imprint  on  the  marble.  Professor  Storer  observes  that  "  it  is  to  be 
noted  that  this  action  by  chemical  corrosion  through  the  roots  is  incessant 
and  continuous."  The  lichen  Stereocaulon  Vesuvianum,  which  grows  on 
rocks,  and  among  them  on  Vesuvian  lavas,  affords  one  ninth  its  weight  of 
ash ;  which  from  one  Vesuvian  specimen,  according  to  Eoth,  contained  silica 
46-41,  alumina  19-67,  Fe203  6-88,  FeO  4-17,  magnesia  5-23,  lime  10-53,  soda 
2-02,  potash  4-09  =  99-00.  For  other  analyses,  see  page  75. 

The  microbes,  or  Bacteria,  are  at  the  bottom  in  much  of  the  world's  chem- 
istry. They  do  not  get  food  from  carbon  dioxide,  but,  like  true  Fungi,  find 
it  in  other  compounds :  for  example,  those  consisting  of  carbon,  hydrogen, 
and  oxygen,  as  sugar,  starch ;  or  those  containing  these  elements  and  nitro- 
gen, etc.,  as  albumen,  muscle,  or  even  a  mineral  sulphate;  they  taking 
the  part  of  the  compound  required  for  food,  and  leaving  the  rest  to 


CHEMICAL    WORK.  137 

form  other  products,  at  the  same  time  usually  giving  out  carbonic  acid  as 
a  result  of  the  plant's  assimilation.  The  processes  of  oxidation  and  deoxi- 
dation  are  carried  on  by  them  ;  and  it  is  a  question  whether,  in  the  particular 
cases  mentioned  on  the  preceding  pages,  the  changes  are  not  dependent  on 
the  presence  of  microbes.  They  set  sulphur  free  from  sulphates  (genus 
Beggiatoa) ;  make  ammonia  and  nitrates  (Micrococcus  nitrificans) ,  deoxidize 
nitrates  and  other  salts ;  aid  plants  in  taking  up  nitrogen  through  the  roots  ; 
probably  aid  animals  in  their  digestive  processes,  besides  causing  some  of 
their  diseases;  they  are  the  basis  of  all  processes  of  fermentation,  and 
are  concerned  fundamentally  in  animal  putrefaction  and  vegetable  decay. 
Tyndall  proved  that  flesh  would  not  decay  if  shut  away  from  Bacteria  — 
the  strong  affinities  of  its  elements  being  unable  to  take  a  start  without 
help  from  these  minutest  of  plants.  The  Bacteria  are  the  smallest  of 
workers  and  among  the  largest  of  producers. 

In  garden  earth  which  is  free  from  compost,  as  T.  Leone  found,  the  nitrification  process 
converts  the  nitrous  acid  into  nitrate  ;  while,  on  adding  compost,  the  nitrate  is  deoxidized, 
and  ammonia  is  given  out ;  or  in  gelatine  or  other  proteid  substance  and  water,  the  organic 
substance  is  rapidly  oxidized,  attended  by  denitrification  and  the  production  of  ammonia. 
Bacteria  liquify  muscle  and  coagulated  gelatine,  and,  according  to  Brunton  and  Mac- 
fadyen,  by  producing  a  peptone-like  solvent ;  and  the  same  kinds  produce  fermentation 
in  starch  and  similar  non-nitrogenous  carbo-hydrogen  materials. 

This  organic  source  of  nitrates  explains  their  occurrence  in  the  earth  of  caverns, 
or  beneath  sheds,  and  in  other  covered  places ;  also  of  the  loosening  of  the  sands  of  sand- 
stones in  such  places  —  an  agency  that  may  in  time  cause  a  vast  amount  of  degrada- 
tion and  removal. 

The  native  nitrate  is  usually  either  sodium  or  calcium  nitrate,  but  sometimes 
potassium  nitrate.  The  latter,  which  is  salt-peter  of  the  shops,  is  usually  made  from 
the  others.  In  Kentucky  caves  the  calcium  nitrate  occurs,  the  caves  being  in  limestone. 
Sodium  nitrate  exists  in  the  district  of  Tarapaca,  northern  Chile,  over  a  great  extent  of 
surface,  3300  feet  above  the  sea,  in  beds  several  feet  thick,  which  have  a  covering  of  earth 
and  a  layer  of  gypsum,  and  contain  some  common  salt.  Moreover,  underneath  the  bed 
occur  common  salt,  glauber  salt,  gypsum,  magnesia  alum,  and  large  quantities  of  borates ; 
all  of  which  indicate  deposits  from  hot  springs  or  evaporated  sea  water.  But  the  source 
of  the  nitrate  remains  unexplained.  This  Tarapaca  region  of  western  South  America  is 
much  like  the  Great  Basin  of  North  America  in  position,  dryness,  and  saline  deposits. 


MECHANICAL  WORK  OF  CHEMICAL  PRODUCTS. 

In  oxidation  and  other  processes  yielding  solid  products,  particles  of  the 
new  material,  when  formed  among  the  grains  of  the  surface  portion  of  a  rock, 
or  in  its  rifts,  act  like  growing  wedges  in  loosening  and  detaching  the  grains, 
and  opening  and  extending  rifts.  The  following  figure  represents  a  piece  of 
quartzyte  from  Canaan,  Conn.,  divided  up,  or  septated,  by  the  oxidation 
process.  It  looks  like  breccia,  in  which  limonite  is  the  cement ;  and  speci- 
mens from  the  region  were  long  so  considered.  But  it  was  produced  by 
the  formation  and  infiltration  of  limonite.  The  rifts  were  thus  widened  into 


138 


DYNAMICAL   GEOLOGY. 


139. 


Quartzyte  septaria.    D.  '84. 


140. 


rents;  moreover,  the  iron  oxide  spread  either  side,  staining  the  rock,  pro- 
ducing the  appearance  of  very  wide  rifts.     Along  one  rift  there  is  an  open 

space  from  the  loss  of  grains,  and  in  it  a  crust 
of  newly  formed  quartz  crystals.  The  process 
often  results  in  pushing  the  pieces  out  of  place. 
Where  saline  efflorescences  —  as  alums,  ni- 
trates, alkaline  carbonates,  or  chlorides  —  are 
produced  in  the  pores  of  a  sandstone,  the  surface 
grains  are  successively  pried  off.  Much  denuda- 
tion is  thus  produced,  especially  in  arid  regions. 
The  process  often  makes  a  series  of  excavations 
along  the  front  of  bluffs.  The  process  goes  on 
most  actively  in  covered  places  and  during  the 
heat  of  the  day.  A  shale  often  has  its  laminae 
separated  by  layers  of  the  salt  or  oxide,  and  fragments  detached. 

Displacement  by  intrusion  of  crystalline  material  is  a  common  process. 
The  following  figure  illustrates  a  case  in  which  crystals  of  tourmaline  in 
mica  schist  are  pushed  apart  at  planes  of  fracture  by  intruding  quartz  (the 
dotted  portion)  from  a  siliceous  solution.  After  the  first  deposit  of  quartz 
within  the  fracture,  the  additions  were  made  between  this  deposit  and  the 
adjoining  part  of  the  crystal, 
and  so  the  wedging  apart 
went  on.  A.  H.  Worthen  has 
described  Crinoids,  from  the 
Keokuk  limestone,  as  split 
open  and  enlarged  in  this 
way,  and  one  Barycrinus  that 
was  thus  made  a  foot  in  di- 
ameter. The  tubular  stems 
are  increased  four  to  six  di- 
ameters in  the  process.  The 
siliceous  solution  supplying 
the  quartz  of  the  Keokuk 
limestone  was  probably  not 
heated. 

The  displacements  may  be  great  when  large  masses  of  a  rock  undergo 
change  to  a  kind  requiring  additional  space.  In  the  change  of  a  bed  of 
anhydrite  to  gypsum  the  increase  of  bulk,  due  to  the  added  water  (page  128), 
is  nearly  60  per  cent.  Dividing  the  atomic  weight  of  anhydrite,  which  is 
136,  by  the  specific  gravity,  2-95,  gives  46-1  for  the  bulk ;  and  that  of  gypsum, 
172,  by  its  specific  gravity,  2-33,  gives  the  bulk  73-8,  making  thus  the  gain 
in  bulk  from  461  to  73-8.  The  change  is  hence  attended  by  a  breaking 
and  displacement  of  any  overlying  beds  of  rock.  In  the  change  of  calcite 
to  true  dolomyte,  (JCa-J-Mg)  CO.,,  there  is  a  diminution  in  bulk  of  one 
eighth  per  cent  (or  one  tenth,  if  the  composition  is  (-f-Ca  -JMg)  C03)  ;  which, 


Broken  crystals  of  tourmaline  displaced  by  intruded  quartz, 
Lenox,  Mass.     D.  '85. 


CHEMICAL   WORK.  139 

if  it  takes  place  in  a  bed  of  calcite  after  its  consolidation,  would  cause  frac- 
tures, or  make  the  rock  porous  and  thus  capable  of  holding  much  mineral 
oil  (page  134),  as  in  the  Findlay  oil  region  of  Ohio. 

CONCRETIONARY  CONSOLIDATION. 

The  methods  of  consolidation  that  have  been  mentioned  in  the  preced- 
ing pages  are  (1)  by  calcareous  waters ;  (2)  by  ferruginous  waters ;  (3)  by 
siliceous  solutions.  Limestones,  and  rocks  only  partly  calcareous,  have  been 
consolidated  almost  solely  by  the  first  of  these  methods.  The  second  method 
is  feeble  in  its  results,  and  occurs  in  gravel  deposits.  Rocks  that  are  colored 
by  iron  oxide,  and  appear  to  have  a  ferruginous  cement,  have  usually  been 
solidified  by  the  third  method. 

Consolidation  is  often  commenced  or  attended  with  concretionary  consoli- 
dation, or  accretion  around  centers  throughout  the  mass,  as  illustrated  on 
page  97.  Isolated  concretions  often  form  in  deposits  of  earth,  clay,  or  other 
material,  when  they  contain  disseminated  calcareous  grains  (derived  from 
ground  shells,  or  any  other  source).  Percolating  waters,  aided  by  the  car- 
bonic or  humus  acids  which  such  waters  are  likely  to  contain,  dissolve  the 
grains  and  deposit  the  material,  in  a  drying  time,  around  grains,  or  any 
small  object,  as  a  nucleus.  In  like  manner,  concretions  of  limonite  and 
iron  carbonate  are  made,  if  any  ferruginous  grains  or  any  decomposable  iron- 
bearing  mineral  is  present.  Occasionally  other  materials  make  disseminated 
concretions. 

The  form  of  the  concretion  is  not  owing  to  any  central  control  of  the 
molecular  deposition,  but  to  the  regular  progress  of  the  superficial  accretion, 
and  to  the  rate  of  supply  of  the  mineral  solution  in  vertical  and  horizontal 
directions,  together  with  the  shapes  of  the  nuclei. 

The  growth  of  the  concentric  forms  above  described  is  peripheral.  There 
is  also  centripetal  consolidation,  or  from  the  exterior  inward.  It  commences 
outside,  owing  to  outside  evaporation  and  the  consequent  deposition  of  the 
concreting  agent.  The  agent  is  commonly  ferruginous.  This  process  of 
outside  drying  is  exemplified  by  the  drying  away  of  a  spot  of  milk  two 
inches  or  so  in  diameter  on  a  slab  of  stone  (as  observed  by  the  author)  :  the 
evaporation  goes  on  at  the  outer  margin,  and  makes  there  the  first  ring, 
capillary  attraction  inside  of  this  ring  contributing  material  toward  it; 
this  outer  ring  completed,  another  ring  begins  and  forms  at  the  new  outer 
margin  of  the  milk-spot;  and  so  ring  after  ring  forms,  until  the  spot  of 
milk  is  reduced  to  a  series  of  whitish  rings.  On  the  same  principle,  shell 
after  shell  may  form  in  a  sand-bed  penetrated  with  a  ferruginous  solution, 
because  drying  is  gradual  from  the  outside ;  or  there  may  be  a  single  outer 
shell,  with  loose  sand  inside  ;  or  a  central  ball  in  the  loose  sand.  The  center 
of  the  concretion  may  originally  have  been  a  piece  of  the  decomposing  iron- 
bearing  mineral  which  afforded  the  ferruginous  solution. 

The  concentric  rings  of  ferruginous  coloration  in  Fig.  141  had  probably 


140 


DYNAMICAL   GEOLOGY. 


this  mode  of  origin.     The  two  sets  of  rings  were  either  side  of  a  crack  in 
the  rock,  and  had  together  a  diameter  of  about  twenty  feet. 

Fig.  142  represents  concentric  areolets  between  mud  cracks  in  an  argilla- 
ceous shale,  made  by  siliceous  waters  at  the  time  of  the  consolidation,  when 
the  mud  cracks  were  likewise  filled  with  quartz,  a  layer  of  quartz  being 


142. 


141. 


Concentric  discoloration,  Illewarra,  N.8.W.    D.  '49. 


Concentric  structure,  Australia.     D.  '49. 


deposited  against  each  wall.  Whether  in  this  case  the  concentric  consolida- 
tion was  centrifugal  or  centripetal  is  not  ascertained.  Seashore  wear  of  the 
rock  brought  the  structure  to  view. 

See  further,  on  Lithophysce,  page  337. 


II.   LIFE:   ITS  MECHANICAL   WORK  AND   ROCK   CONTRIBUTIONS. 

The  making  of  rocks  out  of  organic  contributions,  and  the  protective, 
transporting,  and  destructive  effects  of  life,  are  the  subjects  here  under 
consideration. 

GENERAL  REMARKS  ON  ROCK-MAKING. 

1.    Materials  Afforded  by  Plants  and  Animals. 

The  organic  contributions  to  rock-making  are  mentioned  on  page  71.  It 
appears  that 

PLANTS  afford  — 

Calcareous  material  for  rocks :  mainly  through  Nullipores  and  Coccoliths, 
and  other  calcareous  Algae  or  the  lowest  of  Cryptogams. 

Siliceous  material :  through  Diatoms,  and  some  confervoid  Algae ;  and  spar- 
ingly through  other  plants,  the  ashes  of  which  afford  some  silica  and  alumina. 

Carbonaceous  materials :  through  plants  of  all  kinds,  but  especially  those 
that  flourish  in  wet  soils  and  marshes,  where  means  of  burial  are  convenient. 

ANIMALS  afford  — 

Calcareous  material :  through  Rhizopods  among  Protozoans  ;  Spongiozoans 
with  calcareous  spicules,  to  a  very  small  extent ;  Actinozoaiis,  or  the  Corals  ; 
Hydrozoans  of  the  Hydroid  section;  the  lower  Echinoderms  or  the  Crinoids 
and  Cystoids,  and  other  Echinoderms  sparingly;  Molluscoids,  as  the  Brachio- 


LIFE  :    ITS   MECHANICAL   WORK   AND   ROCK   CONTRIBUTIONS.      141 

pods  and  Bryozoans ;  Mollusks  of  all  the  divisions ;  Articulates,  or  Worms 
and  Arthropods,  very  sparingly  ;  and  sparingly,  Fishes  among  Vertebrates, 
and  very  sparingly,  other  Vertebrates. 

Siliceous  material:  through  Kadiolarians  among  Protozoans;  and  exten- 
sively, Spongiozoans  having  siliceous  spicules  or  skeleton. 

Carbonaceous  materials  :  sparingly  through  the  decomposition  of  aquatic 
species  and  the  dissemination  of  organic  matters  in  bottom  muds. 

Plwspliatic  materials  :  chiefly  through  excrementitious  matters  ;  sparingly 
from  shells  of  some  of  the  lower  Brachiopods,  and  of  Pteropods ;  sparingly 
from  tests  of  Trilobites,  Crustaceans,  and  other  Arthropods,  and  bones  of 
Vertebrates  ;  and  animal  tissues.  For  analyses  see  page  72. 

2.    Relations  of  the  Kinds  of  Life  to  Rock-making. 

The  fitness  of  species  for  rock-making  depends  not  only  on  the  amount 
and  character  of  their  stony  secretions,  but  also  on  their  geographical  distri- 
bution, and  this  on  their  relations,  as  regards  growth,  to  temperature,  light, 
moisture,  and  the  composition  and  mechanical  condition  of  the  air,  waters, 
or  soil  inhabited;  the  height  over  the  land,  the  depth  in  the  water,  and  all 
conditions  affecting  growth  and  burial. 

Marine  species  of  plants  and  animals  are  those  most  likely  to  become 
fossils,  and  so  to  contribute  to  rock-formations ;  and,  among  terrestrial  spe- 
cies, those  that  live  in  lakes  or  marshes,  or  along  their  shores  or  borders. 
The  reasons  are  two  :  (1)  Because  almost  all  fossiliferous  rocks  are  of  marine 
origin ;  and  (2)  because  organisms  buried  under  water,  or  in  wet  deposits, 
are  preserved  from  that  complete  decomposition  to  which  many  are  liable 
when  exposed  on  the  dry  soil,  and  are  also  protected  from  other  sources 
of  destruction. 

Over  the  land,  the  chance  of  burial  is  very  small.  Plants  and  all  animal 
matter  pass  off  in  gases,  when  exposed  in  the  atmosphere  or  in  dry  earth ; 
and  bones  and  shells  become  slowly  removed  in  solution,  when  buried  in 
sands  through  which  waters  may  percolate.  Vertebrate  animals,  as  Fishes, 
Eeptiles,  etc.,  which  fall  to  pieces  when  the  animal  portion  is  removed,  require 
speedy  burial  after  death,  to  escape  destruction  from  this  source  as  well  as 
from  animals  that  would  prey  upon  them. 

Among  Insects  the  species  that  frequent  marshy  regions,  and  especially 
those  whose  larves  live  in  the  water,  are  the  most  common  fossils,  as  the 
Neuropters  ;  while  Spiders,  and  the  Insects  that  live  about  the  flowers  of  the 
land,  are  of  rare  occurrence.  Waders,  among  Birds,  are  more  likely  to 
become  buried  and  preserved,  than  those  which  frequent  dry  forests.  But, 
whatever  their  habits,  Birds  are  among  the  rarest  of  fossils,  because  they 
usually  die  on  the  land,  are  sought  for  as  food  by  numberless  other  spe- 
cies, and  have  slender  hollow  bones  that  are  easily  destroyed.  Mastodons 
have  been  mired  in  marshes,  and  thus  have  been  preserved  to  the  present 
time;  while  the  thousands  that  died  over  the  dry  plains  and  hills  have 
left  no  relics. 


142  DYNAMICAL   GEOLOGY. 

The  animals  generally  of  the  ocean  are  little  liable  to  extermination  from 
changes  of  climate  over  the  land  ;  and  hence  some  marine  invertebrate  species 
of  the  early  Tertiary,  many  of  the  later,  and  all  of  the  Quaternary,  have 
continued  on  until  now,  while,  as  regards  terrestrial  animal  life,  there  were 
in  this  interval  many  successive  faunas. 

The  lowest  species  of  life' are  the  best  rock-makers;  namely,  Corals,  Cri- 
noids,  RhizopodSj  Diatoms,  Millepores,  Bryozoans,  Brachiopods,  Mollusks ; 
for  the  reason  that  the  structures  of  only  the  simplest  kinds  can  consist 
mostly  of  stone  and  still  perform  all  their  functions.  Multiplication  of  bulk 
for  bulk  is  more  rapid  with  the  minute  and  simple  species  than  with  the 
higher  kinds  ;  for  all  animals  grow  principally  by  the  multiplication  of  cells; 
and  when  single  cells  or  minute  groups  of  them,  as  in  the  Rhizopods,  are 
independent  animals,  the  increase  may  still  be  the  same  in  rate  per  cubic 
foot,  or  even  much  more  rapid,  on  account  of  the  simplicity  of  structure. 

While,  therefore,  we  may  conclude  that  we  have,  in  known  fossils,  a  fair 
though  incomplete  representation  of  the  marine  life  of  the  globe,  we  know 
very  little  of  its  terrestrial  life,  —  enough  to  assure  us  of  its  general  course 
of  progress,  but  not  enough  for  any  estimate  of  the  number  of  living  species 
over  the  land ;  or  for  safe  deductions  as  to  lines  of  succession. 

Geology  may  have  within  reach  of  study  fossils  representing  a  twentieth 
of  its  marine  life ;  but  it  has  not  more  than  a  thousandth  of  its  terres- 
trial life. 

Some  examples  of  marine  accumulation.  —  (1)  Beds  of  oysters,  along  with 
other  living  species,  exist  in  the  shallow  seas,  as  off  the  coast  of  North 
America,  but  in  waters  too  deep  for  disturbance  by  the  waves.  Sands  or  earth 
encroach  upon  them  through  the  marine  currents,  but  not  to  the  destruction 
of  the  species.  Afterward,  through  some  geological  change,  beds  of  detritus 
are  washed  over  them,  exterminating  the  oysters  and  perhaps  other  species 
also.  This  is  one  case ;  and  in  it  the  fossils  are  unbroken.  (2)  In  another 
place,  the  relics  of  the  life  of  the  coast,  the  shells,  Corals,  Crustaceans,  etc., 
live  so  near  the  sea  level  as  to  be  within  reach  of  the  waves,  and  hence  they 
may  be  dislodged  at  times  of  heavy  storms,  and  may  become  ground  into 
fragments  and  sand ;  or  they  may  be  contributed  to  under-water  banks,  and 
some  of  the  shells  may  be  scarcely  worn,  and  therefore  good  fossils.  (3)  In 
another  case,  the  worn  fragments,  coarse  and  fine,  may  be  washed  up  a  beach 
and  ground  fine  or  coarse  by  wave  action.  (4)  Again,  the  species  may  live 
over  seashore  flats  which  are  so  shallow  that  the  triturating  waves  act  gently, 
and  all  relics  thereby  become  ground  to  mud,  and  not  one  is  left  to  make  a 
distinguishable  fossil.  (5)  Again,  where  barriers  off  a  seacoast  exclude  the 
salt  water  with  its  marine  life,  not  a  sea-relic  of  any  kind  may  be  put  into 
the  accumulating  seashore  beds  until  some  change  of  conditions  removes  the 
barrier. 

3.    Methods  of  Fossilization. 

In  the  simplest  kind  of  fossilization  there  is  merely  a  burial  of  the  relic 
in  earth  or  accumulating  detritus,  where  it  undergoes  no  change.  Examples 


LIFE:    ITS   MECHANICAL    WORK   AND   BOCK   CONTRIBUTIONS.      143 

of  this  kind  are  not  common.     Siliceous  Diatoms  and  flint  implements  are 
among  them. 

In  general,  there  is  a  change  of  some  kind;  usually,  either  a  loss,  by 
decomposition,  of  the  less  enduring  part  of  the  organic  relic,  with  sometimes 
the  forming  of  new  products  in  the  course  of  the  decomposition,  or  an  altera- 
tion, through  chemical  means,  changing  the  texture  of  the  fossil,  or  petrify- 
ing it,  as  in  the  turning  of  wood  into  stone. 

The  change  may  consist  in  a  fading  or  blanching  of  the  original  colors  ;  in  a  partial  or 
complete  loss  of  the  decomposable  animal  portion  of  the  bone  or  shell,  a  process  that  leaves 
shells  and  bones  fragile.  It  may  be  a  loss  of  part  of  the  mineral  ingredients  by  solvent 
waters,  as  of  the  phosphates  and  fluorides  of  a  bone  or  shell ;  or  a  general  alteration  of  the 
original  organism,  leaving  behind  only  one  or  two  ingredients  of  the  whole  ;  or  a  combin- 
ing of  the  old  elements  into  new  compounds,  as  when  a  plant  decays  and  changes  to  coal  or 
one  or  more  carbohydrogens,  a  resin  to  amber,  animal  matter  to  adipocere.  It  may  be 
merely  one  of  crystallization. 

The  change  often  consists  in  the  reception  of  new  mineral  matter  into  the  pores  or 
cellules  of  the  fossil,  as  when  bones  are  penetrated  by  limestone  or  oxide  of  iron.  Through 
this  method  bones  may  become  as  firm  as  when  living,  though  also  much  heavier. 

The  change  is  frequently  a  true  petrifaction,  in  which  there  is  a  substitution  of  new 
mineral  material  for  the  original ;  as  when  a  shell,  coral,  or  wood  is  changed  to  a  siliceous 
fossil,  through  a  process  in  which  the  organism  was  subjected  to  the  action  of  waters  con- 
taining silica  in  solution.  In  other  cases,  the  organism  becomes  changed  to  calcium  car- 
bonate, as  in  much  petrified  wood  ;  and  in  others,  to  oxide  of  iron,  or  to  pyrite  ;  and  more 
rarely  to  fluor  spar,  barite,  or  apatite. 

The  mineral  matter  first  fills  the  cells  of  the  wood,  and  then  takes  the  place  of  each 
particle  as  it  decomposes  and  passes  away,  until  finally  the  original  material  is  all  gone. 
Some  fossil  logs  are  carbonized  at  one  end  and  silicified  at  the  other. 

The  silica  in  most  siliceous  petrifactions  has  come  from  siliceous  organisms,  such 
as  species  of  Sponges,  or  shells  of  Diatoms,  from  living  species  of  the  period  that  were 
associated  with  the  fossil  in  the  original  deposit. 


EXAMPLES  OF  THE  FORMATION  OF  STRATA  THROUGH  THE 
AGENCY  OF  LIFE. 

1.   Deposits  from  Pelagic  and  Abyssal  Life. 

1.  Plants.  —  Ordinary  seaweeds,  although  in  general  littoral  species,  float 
widely  over  the  ocean  in  some  seas,  as  in  the  case  of  the  Sargasso  Sea  of 
the  north  Atlantic.  Moreover,  the  shore  seaweeds  are  often  drifted  off  by 
the  currents.  But  the  supply,  while  of  importance  as  food  for  the  animal 
species  of  the  sea-bottom,  makes  no  abyssal  vegetable  deposits.  Dredging 
has  brought  up  no  remains  of  such  deposits. 

But  Diatoms,  which  becloud  the  waters  of  the  southern  ocean,  and  there 
serve  for  the  vegetable  food  of  Whales,  make  the  great  deposits  of  Diatom 
ooze,  as  already  described,  besides  giving  a  sprinkling  of  siliceous  shells  over 
all  other  parts  of  the  ocean's  bottom.  These  shells,  as  stated  by  Murray, 
are  especially  noticeable  in  the  deeper  Ked  ooze,  because  the  carbonic  acid, 
which  removes  calcareous  relics,  leaves  them  uninjured. 


144  DYNAMICAL    GEOLOGY. 

2.  Animals.  —  Radiolarians  or  Rhizopods,  having  siliceous  shells,  make 
Radiolarian  ooze  in  the  deeper  parts  of  the  ocean.  Sponges  contribute 
much  silica  in  the  shape  of  spicules  and  skeletons  to  deposits  from  shallow 
depths  to  the  lowest.  Globigerinse  with  other  Rhizopods  make  Globigerina 
ooze,  especially  between  depths  of  1500  and  2900  fathoms,  but  not  in  the 
higher  latitudes.  Pteropods  are  a  characteristic  of  other  bottom  deposits 
between  500  and  1400  fathoms. 

But  besides  these  characteristic  species  there  are  also  the  solitary  Corals, 
the  Echinoderms,  Mollusks,  and  various  other  abyssal  species,  giving  variety 
to  the  fossils  of  the  sea-bottom.  There  are  also  at  the  bottom  the  relics  of 
the  great  variety  of  pelagic  species  which  after  death  escape  feeders  and 
sink  to  the  bottom.  Murray  says  that,  in  the  course  of  the  Challenger  cruise, 
over  600  Sharks'  teeth  (genera  Carcharodon,  Oxyrliina,  and  Lamna)  and  100 
ear-bones  of  Whales  (genera  Ziphias,  Balcenoptera,  Balcena,  Oca,  and  Del- 
phinus),  along  with  50  fragments  of  other  bones,  were  obtained  in  one  haul 
of  the  dredge  in  the  central  Pacific.  The  locality  was,  however,  not  in 
either  of  the  organic  oozes  mentioned,  but  in  the  "  Red  ooze " ;  and  the 
phosphatic  nature  of  bone  was  its  protection  from  carbonic  acid.  Along 
the  course  of  the  Gulf  Stream  and  of  its  abundant  life,  the  bottom  deposit  is 
largely  earthy  or  "  terrigenous,"  and  sometimes  contains  stones  of  considera- 
ble size  which  were  distributed  by  the  floating  ice  of  the  Glacial  period. 

The  blue  and  gray  muds  of  the  sea-bottom,  which  are  common  in  the 
Pacific,  are  due  to  the  volcanic  dust,  cinders,  and  pumice  with  which  it  has 
been  sprinkled  by  the  ocean's  aerial  volcanoes,  and  to  their  decomposition ; 
and  Phillipsite  (page  136)  is  found  chiefly  in  the  areas  of  the  Red  ooze. 

2.   Deposits  from  Littoral  Species. 

The  process  of  limestone-making  by  shells  and  corals  is  essentially 
the  same  in  its  more  important  steps,  and  therefore  only  the  latter  is 
here  considered. 

CORAL    FORMATIONS. 

Coral  formations  are  made  from  the  calcareous  secretions  of  coral-making 
polyps,  with  large  contributions  from  the  shells  and  other  relics  of  the 
littoral  fauna. 

Coral  formations,  while  of  one  general  mode  of  origin,  are  of  two 
kinds :  — 

1.  Coral  islands.  —  Isolated  coral  formations  in  the  open  sea. 

2.  Coral  reefs.  — Banks  of  coral,  bordering  other  lands  or  islands. 

The  positions  of  the  coral-reef  seas  and  the  causes  of  limitation  are 
explained  on  pages  46,  56,  and  illustrated  on  the  chart,  page  47. 

The  exclusion  of  corals  from  certain  tropical  coasts  is  owing  to  different 
causes  :  —  (1)  Cold  extratropical  oceanic  currents,  as  in  the  case  of  western 
South  America  (see  chart).  (2)  Muddy  or  alluvial  shores,  or  the  emptying 
of  large  rivers ;  for  coral-polyps  require  clear  sea  water  and  generally  a  solid 


LIFE  :    ITS    MECHANICAL   WORK   AND   ROCK   CONTRIBUTIONS.       145 


foundation  to  build  upon.  (3)  The  presence  of  volcanic  action,  which, 
through  occasional  submarine  action,  destroys  the  life  of  a  coast.  (4)  The 
depth  of  water  on  precipitous  shores ;  for  the  reef-making  corals  do  not 
grow  where  the  depth  exceeds  150  feet. 

For  the  last-mentioned  reason,  reefs  are  prevented  from  commencing 
to  form  in  the  deep  ocean.  But  if  by  other  accumulations,  or  in  any  other 
way,  the  bottom  is  brought  up  to  the  limiting  distance  from  the  surface, 
Corals  may  commence  the  making  of  reefs. 

Coral  formations  are  most  abundant  in  the  tropical  Pacific,  where  there  are  290  coral 
islands,  besides  extensive  reefs  around  other  islands.  The  Paumotu  Archipelago,  east  of 
Tahiti,  contains  between  70  and  80  coral  islands ;  the  Carolines,  including  the  Radack, 
Ralick,  and  Gilbert  groups,  as  many  more  ;  and  others  are  distributed  over  the  interme- 
diate region.  The  Tahitian,  Samoan,  and  Fiji  Islands  are  famous  for  their  reefs  ;  also 
New  Caledonia  and  the  islands  to  the  northwest.  There  are  reefs  also  about  some  of  the 
Hawaiian  Islands.  The  Laccadives  and  Maldives,  in  the  Indian  Ocean,  are  among  the 
largest  coral  islands  in  the  world.  The  East  Indies,  the  eastern  coast  of  Africa,  the  West 
Indies,  and  southern  Florida  abound  in  reefs  ;  and  Bermuda,  in  latitude  32°  N. ,  is  a  coral 
group.  Reef-forming  Corals  are  absent  from  western  America,  except  along  the  coast  of 
Central  America  as  far  north  as  the  Gulf  of  California,  and  they  are  mostly  absent  from 
western  Africa,  on  account  of  the  cold  extratropical  currents  that  flow  toward  the  equator : 
for  the  same  reason,  there  are  no  reefs  on  the  coast  of  China.  (See  the  Physiographic 
Chart.) 

1.    Coral  Islands. 

1.  Forms.  —  Atolls.  —  A  coral  island  commonly  consists  of  a  narrow  rim  of 
reef,  surrounding  a  lagoon,  as  illustrated  in  the  annexed  sketch  (Fig.  143). 

143. 


Coral  island,  or  atoll. 


Such  islands  are  called  atolls,  —  a  name  of  Maldive  origin.  Maps  of  two 
atolls  are  given  in  Figs.  144,  145,  showing  the  rim  of  coral  reef,  the  salt- 
water lake  or  lagoon,  and  the  variations  of  form.  They  are  never  circular. 


144. 


145. 


ATOLLS.— Fig.  144,  Apia,  one  of  the  Gilbert  Islands  ;  145,  Menchikoff,  one  of  the  Carolines. 

The  size  varies  from  a  length  of  fifty  miles  to  two  or  three ;  and,  when  quite 
small,  the  lagoon  is  wanting,  or  is  represented  only  by  a  dry  depression. 


DANA'S  MANUAL  — 10 


146  DYNAMICAL   GEOLOGY. 

The  reef  is  usually  to  a  large  extent  bare  coral  rock,  swept  by  the  wares 
at  high  tide.  In  some  reefs  the  dry  land  is  confined  to  a  few  isolated  points, 
as  in  Fig.  145  ;  in  others,  one  side  is  wooded  continuously,  or  nearly  so,  while 
the  other  is  mostly  bare,  as  in  Fig.  144.  The  higher  or  wooded  side  is  that 
to  the  windward,  unless  it  happens  to  be  under  the  lee  of  another  island. 
On  the  leeward  side,  channels  often  open  through  to  the  lagoon  (e,  Fig.  144), 
which,  when  deep  enough  for  shipping,  make  the  atoll  a  harbor ;  and  some 
of  these  coral-girt  harbors  in  midocean  are  large  enough  to  hold  all  the  fleets 
of  the  world. 

Fig.  146  represents  a  section  of  an  island,  from  the  ocean  (o)  to  the 
lagoon  (I).  On  the  ocean  side,  from  o  to  a,  there  is  shallow  water  for  some 
distance  out  (it  may  be  a  quarter  or  half  a  mile  or  more)  ;  and,  where  not 
too  deep  (not  over  150  feet),  the  bottom  is  covered  here  and  there  with 
growing  corals.  Between  a  and  b  there  is  a  platform  of  coral  rock,  mostly 
bare  at  low  tide,  but  covered  at  high,  having  a  width  usually  of  about  a 

146. 


Section  of  a  coral  island,  from  the  ocean  (o)  to  the  lagoon  (I). 

hundred  yards :  there  are  shallow  pools  in  many  parts  of  it,  abounding  in 
living  corals  and  other  kinds  of  tropical  life :  toward  the  outer  margin,  it  is 
quite  cavernous ;  and  the  h.oles  are  frequented  by  Crabs,  Fishes,  etc.  At  b 
is  the  white  beach,  six  or  eight  feet  high,  made  of  coral  sand  or  pebbles  and 
worn  shells  :  b  to  d  is  the  wooded  portion  of  the  island.  The  whole  width, 
from  the  beach  (b)  to  the  lagoon  (c),  is  commonly  not  over  300  or  400 
yards.  At  c  is  the  beach  on  the  lagoon  side,  and  the  commencement  of 
the  lagoon.  Corals  grow  over  portions  of  the  lagoon,  —  although,  in  general, 
a  large  part  of  the  bottom,  both  of  the  lagoon  and  of  the  sea  outside,  is  of 
coral  sand. 

Beyond  a  depth  of  150  feet  there  are  no  growing  corals,  except  some 
kinds  that  enter  but  sparingly  into  the  structure  of  reefs. 

2.  Coral-reef  rock.  —  The  rock  forming  the  coral  platform  and  other  parts 
of  the  solid  reef  is  a  white  limestone,  made  out  of  corals  and  shells.     In 
some  parts  it  contains  imbedded  corals ;  in  others,  it  is  as  compact  as  any 
Silurian  limestone  and  without  a  fossil  of  any  kind,  unless  an  occasional 
shell.      The  compact  non-fossiliferous  kinds  are  formed  in  the  lagoons  or 
sheltered  channels ;  the  kinds  made  of  broken  corals,  on  the  seashore  side, 
in  the  face  of  the  waves  ;  those  made  of  corals  standing  as  they  grew,  in 
sheltered  waters,  where  the  sea  has  free  access.     Large  portions  are  a  coral 
and  shell  conglomerate. 

3.  Coral  beach-rock.  —  The  beach-rock  is  made  from  the  loose  coral  sands  of 
the  shores,  which  are  thrown  up  by  the  waves  and  winds.     The  sands  become 


LIFE  :    ITS   MECHANICAL   WORK   AND   ROCK   CONTRIBUTIONS.      147 

cemented  into  a  porous  calcareous  sandstone,  or,  where  pebbly,  into  a  coral 
pudding-stone.  It  forms  layers,  or  a  laminated  bed,  along  the  beach  of  the 
lagoon,  and  also  on  the  seashore  side,  sloping  generally  at  an  angle  of  five 
to  eight  degrees  toward  the  water,  but  sometimes  at  a  larger  angle,  this 
depending  on  the  slope  of  the  beach  at  the  place.  The  rock  is  sometimes 
an  oolyte,  owing  to  the  coating  of  the  grains  with  the  calcareous  cement  as 
solidification  goes  on.  Oolyte  is  especially  common  where  accumulations  of 
sand  make  large  sand-flats  partly  emerged  at  low  tide. 

4.  Formation  of  the  coral  reef.  —  A  reef -region  is  a  plantation  of  living 
corals,  in  which  various  species  are  growing  together  in  crowded  thickets, 
or  in  scattered  clumps,  over  fields  of  coral  sand.     Besides  corals  and  shells, 
there  are  also  calcareous  plants,  called  Nullipores,  growing  over  the  edge  of 
the  reef,  in  the  face  of  the  breakers,  as  shown  by  Darwin,  and  attaining 
considerable  thickness.     Even  the  delicate  branching  kinds  sometimes  make 
thick  beds,  as  observed  by  Agassiz  in  the  Florida  seas.     Bryozoans  add  a 
little  to  the  material,  occasionally  making  large  massive  corals.     In  Paleozoic 
time,  both  branching  and  massive  kinds  contributed  largely  to  limestone 
formations. 

5.  Action  of  the  waves.  —  The  waves,  especially  in  t]ieir  heavier  move- 
ments, sweeping  over  the  coral  plantations,  may  be  as  destructive  as  winds 
over  forests.     They  tear  up  the  corals,  and,  by  incessant  trituration,  reduce 
the  fragments  to  a  great  extent  to  sand ;  and  the  debris  thus  made  and  ever 
making  is  scattered  over  the  bottom,  or  piled  upon  the  coast  by  the  tide,  or 
swept  over  the  lower  parts  of  the  reef  into  the  lagoon,  or  drifted  off  by  the 
currents  for  deposition  elsewhere.     The  corals  keep  growing ;  and  this  sand 
and  the  fragments  go  on  accumulating:  the  consolidation  of  the  material 
thus  accumulated  makes  the  ordinary  reef-rock.     Thus,  by  the  help  of  the 
waves,  a  solid  reef-structure  is  formed  from  the  sparsely  growing  corals. 

Where  the  corals  are  protected  from  the  waves,  they  grow  up  bodily  to 
the  surface,  and  make  a  weak,  open  structure,  instead  of  the  solid  reef-rock ; 
or,  if  it  be  a  closely  branching  species,  so  as  to  be  firm,  it  still  wants  the 
compactness  of  the  reef  that  has  been  formed  amid  the  waves. 

6.  History  of  the  emerging  atoll.  —  The  growing  corals  and  the  accumulat- 
ing debris  reach,  at  last,  low-tide  level.     The  waves  continue  to  pile  up  on 
the  reef  the  sand  and  pebbles  and  broken  masses  of  coral, — some  of  the 
masses  even  200  or  300  cubic  feet  in  size,  —  and  a  field  of  rough  rocks 
begins  to  appear  above  the  waves ;  and  finally  a  beach  is  completed.     The 
sands,  now  mostly  above  the  salt  water,  are   planted   by  the  waves   with 
seeds;    trailing   shrubs    spring   up;    and   afterward,    as   the   soil    deepens, 
palms  and  other  trees  rise  into  forests,  and  so  the  finished  atoll  receives 
its  foliage. 

The  windward  side  of  such  islands  is  the  highest,  because  here  the  winds 
and  waves  act  most  powerfully.  But  where  the  leeward  side  of  one  part  of 
the  year  is  the  windward  of  another,  the  two  may  not  differ  much.  The 
water  that  is  driven  by  the  winds  or  tides  over  the  reef,  into  the  lagoon, 


148  DYNAMICAL  GEOLOGY. 

tends  by  its  escape  to  keep  one  or  more  passages  open,  which,  when  suffi- 
ciently deep,  make  entrances  for  shipping. 

2.    Coral  Reefs. 

The  coral  reefs  around  other  lands  or  islands  rest  on  the  bottom  along 
the  shores.  They  are  either  fringing  or  barrier  reefs,  according  to  their 
position.  Fringing  reefs  are  attached  directly  to  the  shore,  while  barrier 
reefs,  like  artificial  moles,  are  separated  from  the  shore  by  a  channel  of 
water.  The  island  represented  in  Fig.  147  has  a  fringing  reef  (/),  and  a 
barrier  reef  (6)  with  an  intervening  channel.  To  the  right  of  the  middle 
the  reef  is  wanting,  because  of  the  depth  of  water ;  and,  farther  to  the  right, 
there  is  only  a  fringing  reef.  Fig.  149  is  a  map  of  an  island  with  a  fringing 
reef;  and  Figs.  150-152,  others,  with  barrier  reefs.  At  two  points  through 
the  barrier  reef,  in  Fig.  147,  there  are  openings  to  harbors  (7i).  The  chan- 
nels from  harbor  to  harbor  around  an  island  are  sometimes  deep  enough 


View  of  a  high  island  with  barrier  and  fringing  reefs. 

for  ship  navigation,  and  occasionally,  as  off  eastern  Australia,  fifty  or  sixty 
miles  wide ;  but  they  are  generally  too  shallow  for  boats.  The  barrier  some- 
times becomes  wooded  for  long  distances,  like  the  reef  of  an  atoll;  but 
commonly  the  wooded  portion,  if  any  exists,  is  confined  to  a  few  islets. 
Barrier  and  fringing  reefs  are  formed  like  atoll  reefs ;  and  special  explana- 
tions are  needless. 

The  reefs  adjoining  lands  have  sometimes  great  width.  On  the  north 
side  of  the  Fijis,  the  reef -grounds  are  five  to  fifteen  miles  in  width.  In 
New  Caledonia,  they  extend  150  miles  north  of  the  island,  and  50  south, 
making  a  total  length  of  400  miles.  Along  northeastern  Australia,  they 
stretch  on,  although  with  many  interruptions,  for  1000  miles,  and  often 
at  a  distance,  as  just  stated,  of  50  or  60  miles  from  the  coast,  with  a  depth 
of  300  or  360  feet  between.  But  the  reefs,  as  they  appear  at  the  surface, 
even  over  the  widest  reef-grounds,  are  in  patches,  seldom  over  a  mile  or  two 
broad.  The  patches  of  a  single  reef-ground  are,  however,  connected  below 
by  coral  rock,  which  is  struck,  in  sounding,  at  a  depth  usually  of  10  to  40 
or  50  feet. 

The  transition  in  the  inner  channels,  from  a  bottom  of  coral  detritus  to 
one  of  common  mud  or  earth  derived  from  the  hills  of  the  encircled  island, 
is  often  very  abrupt.  Streams  from  the  land  bring  in  this  mud,  and  distribute 
it  according  to  their  courses  through  the  channels. 


LIFE:    ITS   MECHANICAL    WORK   AND   ROCK   CONTRIBUTIONS.       149 

3.    Origin  of  the  Forms  of  Reefs,  —  the  Atoll  and  the  Distant  Barrier. 

The  origin  of  the  atoll  form  of  reefs  was  first  explained  by  Darwin. 
According  to  his  theory,  each  atoll  began  as  a  fringing  reef,  around  an 
ordinary  island ;  and  the  slow  sinking  of  the  island  till  it  disappeared,  while 
the  reef  continued  to  grow  upward,  left  the  reef  at  the  surface,  a  ring  of 
coral  around  a  lake. 

As  reef-forming  corals  grow  only  within  depths  not  greater  than  150 
feet,  the  bottom  on  which  they  began  must  have  been  no  deeper  than  this ; 
and  as  such  a  shallow  depth  is  to  be  found,  with  rare  exceptions,  only 
along  the  shores  of  lands  or  islands,  the  reef  formed  would  be  at  first 
nothing  but  a  fringing  reef. 

A  fringing  reef,  the  first  step  in  coral  formations,  being  begun,  slow 
subsidence  would  make  it  a  barrier  reef. 

In  the  lower  part  of  Fig.  148,  a  section  of  a  high  island,  ATPB,  is  repre- 
sented. The  horizontal  line  1  is  the  level  of  the  sea,  /  a  section  of  the 
fringing  reef  on  the  left,  and  /'  of  that  on  the  right.  The  reef  depends  for 
its  upward  progress  on  the  growth  of  the  coral,  and  on  the  waves.  The 
waves  act  only  on  the  outer  margin  of  a  reef,  while  the  dirt  and  fresh  water 


148. 


3._ 


Section  of  an  island  bordered  by  a  coral  reef,  to  illustrate  the  effects  of  a  subsidence. 

of  the  land  directly  retard  the  inner  part.  Hence  the  outer  portion  increases 
most  rapidly,  and  retains  itself  at  the  surface,  during  a  slow  subsidence  that 
would  submerge  the  inner  portion.  The  first  step,  therefore,  in  such  a  sub- 
sidence, is  to  change  a  fringing  reef  into  a  barrier  reef  (or  one  with  a  channel 
of  water  separating  it  from  the  shore).  Continued  subsidence  widens  and 
deepens  this  channel.  Then,  as  the  island  begins  to  disappear,  the  channel 
becomes  a  lake,  with  a  few  peaks  above  its  surface ;  and  later,  a  single  peak 
of  the  old  land  is  all  that  is  left.  Finally  this  peak'  disappears,  and  the  coral 
reef  comes  forth  an  atoll,  with  its  lagoon  complete. 

Referring  again  to  the  figure  :  if,  in  the  subsidence,  the  horizontal  line  2 
becomes  the  sea  level,  the  former  fringing  reef  /  is  then  at  b,  a  barrier  reef, 
and  /'  is  at  b1,  and  ch,  ch',  ch"  are  sections  of  parts  of  the  broad  channel  or 
area  of  water  within ;  over  one  of  the  peaks,  P,  of  the  sinking  island,  there 
is  an  islet  of  coral,  i ;  when  the  subsidence  has  made  the  horizontal  line  3 
the  sea  level,  the  former  land  has  wholly  disappeared,  leaving  the  barrier 


150  DYNAMICAL   GEOLOGY. 

reef,  t,  t1,  alone  at  the  surface,  around  a  lagoon,  III,  with  an  islet,  u,  over  the 
peak  T,  which  was  the  last  point  to  disappear. 

These  steps  are  well  illustrated  at  the  Fijis.  The  .island  Goro  (Fig. 
149)  has  a  fringing  reef;  Angau  (Fig.  150),  a  barrier;  Exploring  Isles 
(Fig.  151),  a  very  distant  barrier,  with  a  few  islets;  Numuku  (Fig.  152), 
a  lake  with  a  single  rock.  The  disappearance  of  this  last  rock  would  make 
the  island  a  true  atoll. 

Whenever  the  subsidence  ceases,  the  waves  build  up  the  land  above  the 
reach  of  the  tides ;  seeds  take  root ;  and  the  reef  becomes  covered  with 

foliage. 

149-152.  The  lands  inside  of  coral  barriers,  as 

illustrated  in  these  figures,  very  often  show, 
by  their  narrow  broken  features  and  the 
deep  indentations  that  were  once  valleys, 
that  they  are  sunken  lands,  and  thus  sus- 
tain Darwin's  theory. 

The  atoll  Menchikoff  (Fig.  145)   was 
islands  of  the  Fiji  group:  Fig.  149,  Goro;     evidently  formed,  as  explained  by  Darwin, 
mu'kungaU:  m>  Exploringl8les;  152)Nu-     about  a  high  island,  consisting  of  two  dis- 
tinct ridges  or  clusters  of  summits,  like 
Maui  and  Oahu  in  the  Hawaiian  group. 

If  the  subsidence  be  still  continued,  after  the  formation  of  the  atoll, 
the  coral  island  will  gradually  diminish  its  diameter,  until  finally  it  may 
be  reduced  to  a  mere  sand-bank,  or  become  submerged  in  the  depths  of 
the  ocean.  The  occurrence  of  sunken  atolls,  like  the  Maldives,  is  one  of  the 
strong  arguments  for  the  theory  of  subsidence. 

Thickness  of  reefs.  —  The  thickness  of  a  coral  formation,  supposing  Dar- 
win's theory  to  be  the  true  one,  is  often  very  great.  From  soundings  within 
a  short  distance  of  coral  islands,  it  is  certain  that  this  thickness  is  in  some 
cases  thousands  of  feet.  The  barrier  reefs  remote  from  an  island  stand  in 
deep  water,  approximately  proportional  in  depth  to  the  distance  from  the 
coast-line.  Supposing  the  slope  of  the  bottom  at  the  Gambier  Islands  to  be 
only  five  degrees,  we  find,  by  a  simple  calculation,  that  the  reef  has  a  thick- 
ness of  1200  feet.  In  a  similar  manner,  it  is  found  that  the  thickness  must 
be  at  least  250  feet  at  Tahiti,  and  2000  or  3000  at  the  Fijis. 

The  rate  of  subsidence  required  to  produce  the  results  described  cannot  exceed  the 
rate  of  upward  increase  of  the  reef-ground.  On  page  385  some  facts  are  given  illustrat- 
ing the  exceeding  slowness  of  such  movements.1 

As  coral  debris  is  distributed,  by  the  waves  and  currents,  according  to  the  same  laws 
that  govern  the  deposition  of  silt  on  sea  coasts,  it  does  not  necessarily  follow  that  the 

1  For  further  information  on  the  subject  of  Coral  reefs  and  limestones,  the  reader  may  refer 
to  the  author's  work  on  Corals  and  Coral  Islands,  400  pp.  8vo.,  1891,  based  on  his  Exploring 
Expedition  Report  on  Zoophytes  (740  pp.  4to,  and  61  plates  in  folio,  1846),  and  to  the  chapter  on 
Coral  Reefs  and  Islands  in  his  Expedition  Report  on  Geology  (750  pp.  4to,  with  21  plates  in  folio, 
1849) ;  also  to  Darwin  on  the  Structure  and  Distribution  of  Coral  Reefs,  8vo,  with  maps  and 
illustrations,  London,  1842,  the  last  edition,  by  Professor  T.  G.  Bonney,  in  1889. 


LIFE:  ITS  MECHANICAL  WORK  AND  ROCK  CONTRIBUTIONS.    151 

existence  of  a  reef  in  the  form  of  a  barrier  is  evidence  of  subsidence  in  that  region.  On 
page  224  the  existence  of  sand  barriers  of  similar  position  is  shown  to  be  a  common  feature 
of  coasts  like  that  of  eastern  North  America.  In  the  cases  of  the  barriers  about  the  islands 
of  the  Pacific,  however,  there  is  no  question  on  this  point.  Such  barriers  do  not  form 
about  islands  so  small.  Moreover,  the  great  distances  of  the  reefs  from  the  shores,  in 
many  cases,  and  the  existence  of  islands  representing  all  the  steps  between  that  with  a 
fringing  reef  and  the  true  atoll,  leave  no  room  for  doubt.  The  remoteness  of  the  Australian 
barrier  from  the  continent,  and  the  great  depth  of  water  in  the  wide  channel,  show  that 
this  reef  is  unquestionable  proof  of  a  subsidence,  —  though  it  is  not  easy  to  determine  the 
amount.  Along  the  shores  of  continents,  the  question  whether  a  barrier  coral  reef  is  evi- 
dence of  subsidence  or  not  must  be  decided  by  the  facts  connected  with  each  special  case. 
In  opposition  to  Darwin's  theory  of  subsidence  it  is  held  by  some  writers  that  the  sea- 
bottom  may  have  been  brought  up  toward  the  ocean's  surface  by  deposits  of  other  lime- 
secreting  species,  as  those  of  the  shells  of  Rhizopods,  until  they  were  near  enough  to 
become  next  a  plantation  of  corals,  and  that,  in  this  way,  without  any  subsidence,  atolls 
became  common  within  the  area  of  the  tropical  oceans.  But  the  wide  oceans  are  wonder- 
fully free  from  such  banks ;  and  if  they  were  used,  the  growing  reef  made  over  the  sub- 
merged basement  would  fail  of  its  deep  lagoons.  Excavation  of  lagoon  basins  has  been 
attributed,  by  the  opposing  theorist,  to  the  eroding  action  of  the  carbonic  acid  in  sea 
water,  carried  by  currents  over  the  bank  and  through  depressions  that  ware  likely  to 
form  about  the  center  of  the  bank.  But  many  large  lagoons  have  no  entrance,  and  gen- 
erally there  is  only  a  shallow  entrance ;  and  currents  have  no  power  below  the  level  of  the 
entrance  (or  exit).  J.  Murray  has  proposed  the  theory  that  since  the  fringing  reef  widens 
outward  by  growth  and  wave-action,  this  process  may  be  the  sole  cause  of  the  width  of 
reefs  along  shores.  Against  the  opposing  theories  there  are  the  positive  facts,  that  elevated 
coral  reefs  and  atolls  exist,  which  have  a  thickness  beyond  150  feet.  Among  the  many 
facts  there  are  the  following :  Metia,  an  elevated  atoll,  north  of  Tahiti,  has  a  height  of 
250  feet,  which  is  twice  the  depth  of  growing  reef  corals  ;  Christmas  Island,  in  the  Indian 
Ocean,  1200  feet  in  height,  has  an  exterior  of  coral-made  terraces  to  its  summit.  For 
a  full  discussion  of  this  subject  reference  may  be  made  to  the  author's  work  mentioned 
in  the  note  to  the  preceding  page. 

The  following  are  the  teachings  of  the  coral  reefs  : 

1.  Beds  of  coral  limestone  and  shell  limestone  are  made  (1)  by  accumu- 
lation through  growth ;     2)  by  the  mechanical  action  of  waves  and  marine 
currents ;   (3)  by  consolidation  taking  place  as  the  work  goes  forward. 

2.  Limestones  of  the  purest  kind  on  a  scale  of  great  magnitude  form  in 
the  littoral  zone  within  seas  not  over  150  feet  deep.     The  modern  reefs  in  the 
midst  of  the  ocean  are  narrow  and  have  broad  channels ;  but  over  a  conti- 
nental sea,  the  same  methods  would  produce  solid  limestone  formations  of 
unsurpassed  extent,  fossiliferous  or  unfossiliferous,  and  also  beach  sand-rocks, 
conglomerates,  andoolytes;  and  with  the  aid  of  the  winds,  wind-drift  rocks 
of  coral  sand. 

3.  Great  limestones  are  therefore  not  necessarily,  or  generally,  of  deep- 
water  origin. 

4.  Limestones  attain  great  thickness  at  the  present  time  by  means  of  a 
slow  subsidence,  as  they  have  in  all  geological  time. 

5.  Further :  comparing  littoral  with  abyssal  conditions,  we  learn  that  the 
former  make  stratified  deposits  containing  or  consisting  of  remains  of  litto- 
ral life ;    the  latter  make  unstratified  deposits  containing  or  consisting   of 


152  DYNAMICAL   GEOLOGY. 

pelagic  life.  (See  further,  page  143.)  The  stratified  limestones  and  other 
rocks  of  North  America  have  no  true  deep-water  characteristics.  Wyville 
Thomson  gave  this  as  his  general  conclusion  for  all  continents. 

3.    Deposits  made  by  Continental  Species. 

1.     SILICEOUS    DEPOSITS. 

Conferva-like  Algse,  having  columnar,  vase-shaped  and  furze-like  forms, 
grow  in  the  hot  geyser  waters  of  the  Yellowstone  Park,  which  secrete  opal- 
silica  freely  throughout  the  plant,  as  first  reported  by  W.  H.  Weed.  They 
cause  the  deposition  of  the  silica  from  the  waters  in  a  gelatinous  form, 
making  the  geyserite  basins  and  the  wide-spread  geyserite  deposits.  These 
siliceous  plants  are  described  as  growing  an  inch  upward  in  10  weeks. 

Diatoms  make  beds  in  shallow  ponds  over  the  continents,  and  thick 
deposits  of  them  are  common  beneath  the  peat  of  ordinary  marshes.  Such 
ponds  have  only  the  gentlest  of  waves ;  but  sufficient  to  break  into  pieces 
most  of  the  infinitesimal  shells. 

Diatoms  are  especially  abundant  in  the  warm  waters  of  the  Yellowstone 
Park,  where  the  beds  made  from  them  cover  many  square  miles  in  the 
vicinity  of  active  and  extinct  hot  springs,  and  vary  from  three  to  six  feet 
in  depth.  Near  Monterey,  Cal.,  there  is  a  Diatom  bed  50  feet  thick.  Others 
occur  in  Nevada,  where,  according  to  Ring,  they  alternate  with  beds  of  tufa ; 
and  some  are  200  or  300  feet  thick.  The  material  of  the  beds  looks  like 
chalk,  but  it  often  becomes  partially  solidified  to  opal,  of  a  brown,  yellowish, 
or  greenish  color. 

2.     CALCAREOUS    DEPOSITS. 

1.  The  shells  of  terrestrial  and  freshwater  Mollusks  are  mostly  thin  and 
fragile,  especially  the  Gastropods,  breaking  easily  under  the  gentlest  wave 
action.     Limestones  with  unbroken  shells  as  fossils  are  of  rare  occurrence 
and  small  extent,  forming  only  in  bodies  of  water  too  shallow  for  wind- 
waves.     The  more  common  genera  are  Splio&rium,  Limncea,  Physa,  Planorbis, 
Paludina,  and  Pupa.      The  deposits  over  the  bottoms  of  small  ponds  are 
usually  accumulations  -of  pulverized  shells,  and  have  a  chalky  aspect.     The 
earthy  and  clayey  beds  of  river  valleys  ordinarily  contain  nothing  of  the 
shells   of   the  valley  except  minute  grains   from  their  wear,  or  calcareous 
concretions  made  from  the  grains.     The  fine  earthy  loess  of  large  valleys 
is  remarkable  for  the  number   of  its   freshwater  shells    (Gastropods),    its 
strongly   calcareous    character,    and   its    calcareous    concretions,    and   bears 
evidence   thus  of   the    sublacustrine   and   shallow  conditions    attending  its 
deposition. 

2.  Loosely  textured  calcareous  rock,  called  tufa  because  of  its  appearance, 
is  formed  from  the  confervoid  Algse  of  the   Yellowstone   Park  and  other 
regions.     It  is  an  aggregation  of  the  algoid  growths,  some  of  which  resemble 
somewhat  the  concretionary  forms  represented  in  Fig.  137  on  page  132. 


LIFE  :    ITS   MECHANICAL   WOKK   AND   KOCK   CONTRIBUTIONS.      153 

Dr.  A.  Rothpletz  has  stated  that,  according  to  his  observations  at 
Great  Salt  Lake,  Utah,  the  concretionary  grains  of  oolyte  are  due  to 
the  growth  and  calcareous  secretion  of  a  minute  Alga  or  water-plant  (1893); 
and  that  they  are  formed  there  within  a  bluish  green  alga-mass.  He  is 
disposed  to  account  thus  for  the  formation  of  ordinary  oolyte.  Oolyte  is 
an  abundant  product  along  the  low  coral-sand  shores  of  southern  Florida, 
and  its  formation  has  been  attributed  to  deposition  from  the  sea  water 
around  minute  grains  of  the  sand,  or  around  some  still  more  minute  shell 
of  a  Diatom  or  other  microscopic  organism. 

3.     PHOSPHATIC    DEPOSITS. 

Guano  beds  are  the  important  deposits  of  phosphatic  material.  The 
origin  and  constitution  of  guano  are  described  on  page  72.  The  composition 
is  approximately :  organic  and  volatile  matter  40  per  cent,  phosphoric  acid 
14,  lime  12,  potash  and  soda  7,  nitrogen  9,  along  with  water.  The  agricul- 
tural value  is  largely  owing  to  the  nitrogen.  Besides  the  kinds  mentioned, 
Bat  guano  is  formed  in  some  caves  ;  and  in  Victoria,  southern  Australia, 
it  has  a  depth  of  30  feet  in  the  Skipton  caves.  The  prominent  localities  of 
guano  are  :  islands  on  the  nearly  rainless  Peruvian  coast,  which  were  worked 
as  early  as  the  sixteenth  century ;  various  islands  of  the  equatorial  Pacific, 
between  155°  W.  and  277°  W. ;  Sombrero  and  neighboring  islands  in  the 
West  Indies,  and  also  large  coastal  areas  in  South  Carolina  and  Florida. 
In  the  West  Indies,  and  in  South  Carolina  and  Florida,  where  the  rains  are 
common,  the  guano  is  mostly  destitute  of  nitrogen,  it  being  the  impure 
calcium  phosphate  made  by  the  filtration  of  rain-waters  through  the  original 
guano,  carrying  the  soluble  phosphates  into  underlying  calcareous  deposits. 
Fossil  shells  and  bones  are  among  the  phosphatized  products. 

4.    Peat  and  other  Carbonaceous  Formations. 

Peat  is  an  accumulation  of  half-decomposed  vegetable  matter,  in  wet  or 
swampy  places  over  the  interior  of  a  continent  or  about  its  estuaries.  In 
temperate  climates,  it  is  due  to  the  growth  mainly  of  spongy  Mosses,  of  the 
genus  Sphagnum,  which  are  very  absorbent  of  water.  Beside  spreading  over 

153. 


Peat-forming  in  progress,  with  a  Diatom  deposit  (d)  over  the  bottom  of  the  pond.    Shaler. 

the  swampy  surfaces,  they  extend  out  a  floating  layer  from  the  borders  of 
shallow  ponds  (6),  as  illustrated  in  Fig.  153,  from  Shaler's  Memoir  on  the 
Origin  and  Nature  of  Soils.  The  floating  layer  (6,  6)  drops  portions  to  the 


154  DYNAMICAL   GEOLOGY. 

bottom  from  its  lower  dying  surface;  for  the  moss  has  the  property  of 
dying  at  the  extremities  of  the  roots  as  it  grows  above.  It  thus  gradually 
takes  possession  of  the  pond,  and  may  form  beds  of  great  thickness. 

In  some  limestone  regions,  the  Sphagnous  mosses  are  replaced  by  species 
of  Hypnum,  as  in  Iowa.  The  leaves  and  stems,  branches  and  stumps,  of 
trees  and  shrubs,  growing  over  the  marshy  region  or  in  shallow  waters,  and 
any  other  vegetation  present,  contribute  to  the  accumulating  bed.  The  fresh- 
water shells  growing  in  the  waters,  and  the  spicules  of  any  sponges,  with 
the  insects,  and  the  carcasses  and  excrements  of  animals  become  included. 
Earthy  material  also  may  be  blown  over  the  marsh  by  the  winds,  or  brought 
by  inflowing  streams. 

In  wet  parts  of  Alpine  regions,  there  are  various  flowering  plants  which 
grow  in  the  form  of  a  close  turf,  and  give  rise  to  beds  of  peat,  like  the  moss. 
In  Fuegia,  although  not  south  of  the  parallel  of  56°,  there  are  large  marshes 
of  such  Alpine  plants,  the  mean  temperature  being  about  40°  F.  On  the 
Chatham  Islands,  380  miles  east  of  New  Zealand,  peat  thus  formed  has 
a  depth  of  50  feet. 

The  dead  and  wet  vegetable  mass  slowly  undergoes  a  change  in  its  lower 
part,  becoming  brownish  black,  loose  in  texture,  and  often  friable,  although 
commonly  penetrated  with  rootlets.  The  change  is  sometimes  continued 
until  coal  is  formed ;  but  unlike  good  coal  it  still  contains  usually  25  to  33 
per  cent  of  oxygen. 

Peat-beds  cover  large  surfaces  of  some  countries,  and  occasionally  have 
a  thickness  of  40  or  50  feet.  The  rate  of  growth  varies  with  the  amount  of 
vegetation,  moisture,  and  other  conditions ;  a  foot  in  depth  may  form  in  five 
to  ten  years.  One  tenth  of  Ireland  is  covered  by  them ;  and  one  of  the 
"mosses"  of  the  Shannon  is  stated  to  be  50  miles  long  and  two  or  three 
broad.  A  marsh  near  the  mouth  of  the  Loire  is  described  by  Blavier  as 
more  than  50  leagues  in  circumference.  Over  many  parts  of  New  England 
and  other  portions  of  North  America,  there  are  extensive  beds,  almost  every 
old  marsh  having  more  or  less  peat  below.  The  amount  in  Massachusetts 
alone  has  been  estimated  to  exceed  120,000,000  of  cords.  The  Dismal  Swamp, 
10  miles  by  30  in  area,  situated  on  the  borders  of  Virginia  and  North  Caro- 
lina, is  for  the  most  part  a  region  of  very  deep  peat. 

Peat-beds  sometimes  contain  standing  trees,  and  entire  skeletons  of  ani- 
mals that  had  sunk  in  the  swamp.  The  peat-waters  have  an  antiseptic 
power,  and  consequently  tend  to  prevent  complete  decay  of  the  vegeta- 
ble matter  of  the  peat-bed.  Flesh  is  sometimes  changed  by  the  burial 
into  adipocere. 

Peat  is  used  for  fuel,  and  also  as  a  fertilizer.  When  prepared  for  burning,  it  is  cut  into 
large  blocks,  and  dried  in  the  sun.  It  is  sometimes  pressed,  in  order  to  serve  as  fuel  for 
steam-engines.  Muck  is  another  name  for  peat,  especially  for  impure  kinds,  when  em- 
ployed as  a  manure  ;  any  black  swamp-earth  consisting  largely  of  decomposed  vegetable 
matter  is  so  called. 

Beds  of  marine  plants  in  the  rocks  of  littoral  regions  are  almost  unknown..    Specimens 


LIFE:  ITS  MECHANICAL  WORK  AND  ROCK  CONTRIBUTIONS.     155 

are  distributed  through  the  formations,  and  have  been  the  source  of  some  coaly  products ; 
but  never  abundantly.  The  trunks  of  Lessonia,  as  large  as  a  man's  thigh,  lie  piled  in  great 
quantities  on  the  shores  of  the  Falkland  Islands.  Moreover,  the  growth  of  sea-weeds  is 
very  rapid.  On  the  coast  of  Scotland,  and  below  low-tide  level,  "a  surface  chiseled 
smooth  in  November,  was  thickly  covered  in  the  following  May  with  ribbon  kelp  2  feet 
long,  and  ordinary  kelp  6  feet  long."  But  no  peat-like  compact  beds  of  marine  Fucoids 
are  known.  Fucoids  contain  74  to  80  per  cent  of  water,  some  nitrogen,  and  are  very  muci- 
laginous ;  and  hence  "  when  they  begin  a  decay  and  become  disorganized,  they  melt  down 
into  a  very  small  bulk,  and  seem  almost  to  dissolve  away."  (Storer.) 

The  great  interest  to  the  geologist  in  this  subject  of  peat-beds  is  the  essen- 
tial identity  between  their  method  of  origin  and  that  of  the  great  accumula- 
tions of  vegetable  debris  out  of  which  coal-beds  were  made.  Both  were 
accumulations  of  leaves  and  stems  of  terrestrial  (not  marine)  plants,  and 
occupy,  as  a  general  thing,  the  region  where  the  plants  to  a  large  extent 
grew.  The  chemical  processes  of  change  were  also  essentially  'the  same. 
The  burial  of  the  ancient  beds  beneath  thick  sediments  in  many  successions, 
as  explained  on  page  712,  has  made  the  chief  differences. 

PROTECTIVE  AND  OTHER  BENEFICIAL  EFFECTS. 

The  protective  effects  of  life  come  chiefly  from  vegetation. 

1.  Turf  protects  earthy  slopes  from  the  wearing  action  of  rills  that  would 
wear  a  bare  surface  into  gullies ;  and  even  hard  rocks  receive  protection  in 
the  same  way. 

2.  Tufts  of  grass  and  other  plants  over  sand-hills,  as  on  seashores,  bind 
down  the  moving  sands  by  their  long  creeping  stems  or  spreading  roots. 

3.  Lines  of  vegetation  along  the  banks  of  streams  prevent  wear  during 
freshets.     When  the  vegetation  consists  of  shrubs  or  trees,  the  stems  and 
trunks  entangle  and  detain  detritus  and  floating  wood,  and  serve  to  increase 
the  height  of  the  margin  of  the  stream. 

4.  Vegetation  on  the  borders  of  a  pond  or  bay  serves  in  a  similar  manner 
as  a  protection  against  the  feebler  wave-action.     In  many  tropical  regions, 
plants  like  the  mangrove,  growing  at  the  water's  edge,  drop  new  roots  from 
the  branches  into  the  shallow  water.    These  roots  act  like  a  thicket  of  brush- 
wood, to  retain  the  floating  leaves,  stems,  and  detritus  ;  and,  as  the  water  shal- 
lows, other  roots  are  dropped  farther  out;  and  thus  they  keep  marching 
outward,  and  subserve  the  double  purpose  of  protecting  and  making  land. 
The  coarse  salt-marsh  grasses  along  seashores  perform  the  same  kinds  of 
geological  work,  being  very  effectual  agents  in  entangling  detritus,  and  in 
protecting  from  erosion. 

5.  Patches  of  forest-trees,  on  the  declivities  in  Alpine  valleys,  serve  to 
turn  the  course  of  the  descending  avalanche,  and  entangle  snows  that,  but  for 
the  presence  of  the  trees,  would  only  add  to  its  extent.     Such  groves  are 
usually  guarded  from  destruction  with  great  care. 

6.  Forests  retard  the  melting  of  snow  and  ice  in  spring,  and  thus  lessen  the 
devastations  of  floods. 


156  DYNAMICAL   GEOLOGY. 

7.  Calcareous  Algae,  called  Nullipores  (page  147),  serve  to  protect  grow- 
ing Corals  and  the  margins  of  coral  reefs  from  wear.  Ordinary  seaweeds 
often  cover  and  protect  the  rocks  of  a  coast  nearly  to  high-tide  level ;  in  the 
higher  latitudes  the  Fucoids  (as  Macrocystis  pyrifera)  are  sometimes  200  to 
300  yards  long,  and  the  broad  green  belt  off  a  coast  breaks  the  force  of 
incoming  waves  so  that  the  rocks  are  saved  from  their  destructive  action. 

The  common  earthworm,  as  Darwin  has  shown  (1881),  transfers  a  great 
amount  of  earth  or  soil  in  the  pellets  it  discharges  at  the  surface.  He  found 
that  the  weight  so  transferred  per  acre  in  a  year  in  four  cases  was  7-56,  14-58, 
16'1,  and  18 '12  tons.  Lobworms,  of  seashores,  are  even  greater  workers, 
according  to  C.  Davison,  who  reports  that  the  amount  of  sand  carried  up  each 
year  on  the  shores  of  Holy  Island,  Northumberland,  was  equivalent  to  1911 
tons  per  acre  (1891).  Marmots  (Spermatophilus  Eversmani),  in  the  Caspian 
steppes,  bring  great  quantities  of  earth  to  the  surface.  In  a  few  years  after 
their  introduction  they  had  brought  up  75,000  cubic  meters  of  earth  to  the 
square  mile.  (Muschketoff,  1887.) 

TRANSPORTING  EFFECTS. 

1.  Seeds  caught  in  the  feathers,  hair,  or  fur  of  animals,  or  contained  in 
the  mud  adhering  to  their  feet,  are  transported  from  place  to  place. 

2.  Seeds  are  eaten  by  animals  as  food,  or  in  connection  with  their  food, 
and  are  dropped  in  another  region  undigested.     At  the  Solomon  Islands,  fruit- 
pigeons  carry  fruit  and  seeds  in  their  crops,  and  have  thus  planted  the  land 
with  trees  from  other  islands.     (Guppy.) 

3.  Ova  of  fish,  reptiles,  and  inferior  animals  are  supposed  to  be  transferred 
from  one  region  to   another  by  birds  and  other  animals.      Authenticated 
instances  of  this  are  wanting. 

4.  Floating  logs  and  seaweeds  carry  Mollusks,  Crustaceans,  Worms,  and 
other  species  from  one  region  to  another,  over  the  broadest  oceans,  along  the 
courses  of  marine  currents.     In  tropical  countries,  islands  of  shrubbery  and 
trees  often  float  away  from  estuaries  into  the  sea,  bearing  with  them  land, 
fresh-water  shells,  and  other  terrestrial  species,  which  there  become  mingled 
with  marine  shells.     A  Boa  constrictor  once  floated,  on  the  trunk  of  a  cedar, 
from  Trinidad  off  South  America  to  the  island  of  St.  Vincent  —  a  distance  of 
at  least  200  miles.     The  great  floating  seaweed  areas  of  the  Sargasso  Sea  in 
the  Atlantic  are  the  dwelling-place  of  vast  numbers  of  marine  species,  includ- 
ing Fishes,  Mollusks,  Crustaceans,  Worms,  etc. 

5.  Migrating  tribes  of  men  carry,  in  their  grain,  or  otherwise,  the  seeds 
of  various  weeds,  and  also,  involuntarily,  Rats,  Mice,  Cockroaches,  and  smaller 
vermin.     The  origin  of  tribes  may  often  be  inferred  from  the  species  of 
plants  and  of  domesticated  and  other  animals  found  to  have  accompanied 
them.1 

1  On  this  general  subject  consult  Wallace's  Island  Life. 


LIFE  :  ITS  MECHANICAL  WORK  AND  ROCK  CONTRIBUTIONS.    157 

DESTRUCTIVE  EFFECTS. 

The  destructive  effects  proceed  either  from  living  plants  or  animals,  or 
from  the  products  of  decomposition.  The  latter  subject  is  briefly  considered 
under  Chemical  Work. 

1.  The  roots  which  come  from  the  sprouting  of  a  seed  in  the  crevice  of  a 
rock,  as  they  increase  in  size,  act  like  wedges,  in  tending  to  press  the  rock 
apart;  and,  when  the  roots  are  of  large  size,  masses  tons  in  weight  may  be 

154. 


Rocks  disrupted  by  roots  of  trees,  between  Gloucester  and  Rockport,  Mass.     Shaler,  '89. 

torn  asunder ;  and  if  on  the  edge  of  a  precipice,  the  detached  blocks  may 
be  pushed  off,  to  fall  to  its  base.  This  is  one  of  the  most  effective  causes  of 
the  destruction  of  rocks.  Many  regions  of  massive  and  jointed  rocks  are 
thickly  covered  with  huge  blocks,  looking  like  transported  bowlders,  which 
are  the  results  of  this  kind  of  upturning.  The  Confervse  and  other  simple 
plants  often  commence  their  wedging  work  in  the  smallest  of  rifts ;  and 
yet  by  constant  growth  cause  great  results.  Moreover,  the  opening  of  rifts 
and  fissures  gives  access  to  moisture,  and  thus  contributes  further  to  rock 
destruction  by  chemical  processes  and  by  frost. 

2.  Boring  animals,  like  the  saxicavous  Mollusks,  make  holes,  often  as 
large  as  the  finger,  and  sometimes  larger,  in  limestone  and  other  rocks,  along 
some  seashores.  Species  of  Saxicava,  Pholas,  Petricola,  Lithodomus,  Gastro- 
chcena,  and  even  some  Gastropods,  Barnacles,  Annelids,  Echini,  and  Sponges, 


158  DYNAMICAL   GEOLOGY. 

have  this  power  of  boring  into  stone.  Various  species  also  bore  into  shells 
or  corals.  In  seven  years,  Carrara  marble,  in  the  sea  south  of  Long  Island, 
became  riddled  with  borings  made  by  a  Sponge,  the  Cliona  sulphured,  of 
Verrill.  Termites,  or  White  Ants,  and  many  other  insects,  especially  when 
in  the  larval  state,  the  Limnoria  among  Crustaceans,  and  the  Teredo,  related 
to  Pholas,  among  Mollusks,  bore  into  wood ;  and  the  last  is  so  destructive  to 
ships,  piles,  and  wharves  that  it  is  often  called  the  Shipworm  or  Pileworm. 

3.  The  tunneling  of  the  earth  by  small  quadrupeds,  as  the  Mole,  and 
by  Crustaceans  like  the  Crawfish,  sometimes  results  in  the  draining  of  ponds, 
and  the  consequent  excavation  of  gullies  or  gorges  by  the  out-flowing  waters. 
The  tunneling  of  the  levees  of  the  Mississippi  by  Crawfish  is  one  cause 
of  breaks,  and  thereby  of  great  floods  over  the  country. 

4.  Animals  using  Mollusks  and  Echinoderms  as  food  make  great  refuse- 
heaps,  or  beds  of  broken  shells.     The  animals  include  Man,  as  well  as  other 
species ;  and  the  beds  made  by  Fishes  off  the  coast  of  Maine,  as  described 
by  Verrill  (who  has  drawn  attention  to  this  mode  of  making  broken  shells), 
are  of  great  extent.     They  might  be  taken  for  beach  deposits.     The  chief 
enemy  of  the  American  Oyster  is  a  Starfish,  which  spreads  its  extensile 
mouth-opening  over  the  young  Oyster,  and  so  gets  it  inside  its  stomach,  and 
then,  as  the  shell  opens,  digests  the  Oyster. 

5.  Fungi  attack  dead  plants  and  animals,  and  rapidly  destroy  them.     They 
do  it  by  excreting  ferments  or  poisons,  which  eat  into  and  destroy  the  tissues. 
Living  plants  often  suffer  from  this  cause  when  in  an  enfeebled  state. 

6.  The  destruction  of  the  vegetation  of  a  region  by  insect  life,  and  that 
of  animals  by  one  another,  are  also  of  great  geological  importance. 

III.   THE  ATMOSPHERE  AS  A  MECHANICAL  AGENT. 

The  weight  of  100  cubic  inches  of  dry  air,  with  the  barometer  at  30  inches, 
and  the  thermometer  at  60°  F.,  is  31  grains ;  and  hence  it  is  but  -^  as  heavy 
as  water  (or  -^  at  32°  F.).  The  weight  of  a  column  of  the  atmosphere  a 
square  inch  in  area  of  section,  when  the  barometric  pressure  is  30  inches,  and 
the  temperature  32°  F.,  is  14-7  pounds.  On  this  basis,  the  total  weight  of 
the  atmosphere  is  about  llf  trillions  of  pounds  (Herschel).  In  England,  an 
atmosphere  of  pressure,  used  as  a  limit  in  connection  with  steam,  is  29-905 
inches  Bar.  at  32°  F.,  or  nearly  14|  pounds  to  the  square  inch;  in  France,  it 
is  760  millimeters,  or  29-922  English  inches,  at  the  same  temperature. 

The  atmosphere,  while  rightly  called  the  earth's  aerial  ocean,  is  an  aerial 
ocean  without  a  definite  upper  surface,  resting  on  an  ever-disturbing  base- 
ment. It  extends  not  only  to  a  height  of  40  miles,  but,  with  increasing 
tenuity,  to  at  least  200  miles,  —  meteorites  having  become  luminous  at  this 
height  as  a  consequence  of  the  friction  of  air.  An  upper  limit  is  supposed 
to  be  determined  by  the  equilibrium  between  the  gravitation  of  the  mole- 
cules of  the  elements  constituting  it  and  the  expansive  force,  decreasing 
upward,  that  separates  the  molecules. 


THE   ATMOSPHERE   AS   A   MECHANICAL   AGENT.  159 

The  basement  on  which  it  rests  —  the  earth's  uneven  surface  —  varies 
widely  in  temperature,  and  this  variation  passes  to  extremes  in  the  higher 
mountains,  whatever  the  zone.  The  atmosphere's  own  temperature,  even 
in  the  tropics,  is  at  the  freezing-point  at  a  height  of  less  than  four  miles. 
Through  these  and  other  conditions  the  atmosphere  has  its  varying  belts 
of  greater  and  less  depth,  —  that  is,  of  higher  and  lower  barometric  pres- 
sure,—  its  areas  of  high  and  low  pressure  moving  in  great  circuits,  and, 
as  a  consequence,  winds,  storms,  cyclones,  tornadoes,  in  its  fruitless  effort 
toward  a  state  of  equilibrium.  These  winds  are  its  chief  means  of  mechani- 
cal work. 

The  Mechanical  Work  of  the  Atmosphere.  —  The  atmosphere  works  mechan- 
ically (1)  by  denudation,  or,  as  it  has  been  termed,  deflation,  with  or  without 
abrasion ;  (2)  by  transportation ;  (3)  by  deposition  ;  and  (4)  through  its 
pressure.  The  work  and  the  results  are  called  Eolian,  from  AioAos,  the  god 
of  the  winds. 

The  force  of  the  wind,  measured  by  the  pressure  on  a  square  foot,  in- 
creases with  the  square  of  the  velocity.  At  5  miles  an  hour,  the  pressure 
is  about  2  ounces  to  the  square  foot ;  at  10  miles,  which  is  that  of  a  light 
breeze,  8  ounces ;  at  20  miles,  a  good  steady  breeze,  2  pounds ;  at  40  miles, 
a  strong  gale,  8  pounds ;  at  60  miles,  18  pounds ;  at  100  miles,  50  pounds. 
The  work  done  is  dependent  largely  on  the  form  of  the  surface  struck. 
This  is  well  shown  in  the  anemometer  made  of  hemispherical  cups :  the 
difference  between  the  pressure  on  the  concave  and  convex  sides  being  such 
that  the  cups  move  one  third  as  fast  as  the  wind,  whereas  with  flat  disks 
there  would  be  no  motion.  A  velocity  of  186  miles  an  hour  (or  170  pounds 
to  the  square  foot)  has  been  registered  by  the  anemometer. 

While  the  lighter  winds,  and  especially  the  great  currents,  like  the  trades, 
have  a  degree  of  regularity  in  movement,  the  storm  winds,  on  which  geo- 
logical work  mainly  depends,  are  hurrying  bodies  of  air  of  inconstant  force, 
breadth,  and  direction.  A  single  storm  includes  all  the  courses  of  the  com- 
pass, and  all  degrees  of  force,  from  lulls  to  extremest  violence ;  and  when 
most  constant,  these  winds  are  still  made  up  of  fitful  blasts.  Under  such  con- 
ditions, abrasion,  transportation,  and  deposition  should  be  greatly  mixed; 
and  this  is  a  striking  feature  of  the  results. 

EOLIAN  DENUDATION  OK  DEFLATION. 

Denudation,  or  wear  by  wind-force,  is  carried  on  (1)  by  simple  wind-impact 
and  (2)  by  impact  when  the  air  is  loaded  with  sand  or  other  material. 

1.  By  simple  impact.  —  The  lighter  work  of  the  winds  is  the  taking  up 
of  dust  from  roads,  sand-fields,  sand-hills,  and  sea-beaches,  to  drift  away  to 
some  other  place.  The  streets  of  most  cities  and  the  roads  of  the  country 
often  afford  examples  of  the  work  on  dry,  windy  days.  It  is  to  be  noted, 
however,  that  a  rather  strong  wind  is  required  for  this  light  deflation  unless 
moving  wheels  first  stir  up  the  dust.  The  result  is  due  to  the  direct  impulse 


160  DYNAMICAL    GEOLOGY. 

of  the  moving  air ;  and  so  it  is  when  the  hurricane  tears  up  trees,  prostrates 
forests,  unroofs  houses,  or  moves  them  from  their  foundations.  These  de- 
structive effects  are  dependent,  as  already  explained,  not  merely  on  velocity, 
but  also  on  the  extent,  form,  and  position  of  the  object  against  which  it 
strikes.  The  adhesion  of  the  hardened  mud  along  the  ruts  of  a  country 
road  may  not  be  overcome  by  a  gale  that  prostrates  forests. 

Besides  lifting  and  transporting  loose  sands,  the  heavier  winds  tear  off 
grains  from  exposed  ledges  or  bluffs  of  rock,  which  the  action  of  the  sun, 
or  oxidation,  or  saline  efflorescences,  or  other  means  have  loosened,  and  thus 
carry  on  the  work  of  denudation. 

2.  By  means  of  the  material  transported.  —  But  the  sand,  gravel,  or  stones 
borne  by  the  winds  give  them  their  chief  denuding  power.  Attention  was 
first  called  to  this  wind  work  by  W.  P.  Blake,  who  described  the  granite 
of  the  Pass  of  San  Bernardino,  Cal.,  as  scratched  like  rocks  of  glacier 
regions,  even  quartz  and  tourmaline  being  finely  polished,  and  the  garnets 
left  projecting  on  pedicels  of  feldspar,  inclined  in  the  direction  of  the  wind ; 
limestone  as  eroded  and  channeled  as  if  by  dissolving  waters.  Mr.  Blake 
observed,  further,  that  the  scratching  and  polishing  effects  were  not  confined 
to  the  Pass,  but  were  visible  over  all  parts  of  the  Colorado  desert  to  the 
eastward,  where  hard  rocks  were  exposed ;  and  he  dwells  on  the  great  impor- 
tance of  this  action  of  the  winds  as  a  means  of  denudation  (1855).  Later 
observers  have  shown  that  many  of  the  bluffs,  needles,  and  towers  of  soft 
sandstone  characterizing  the  scenery  in  different  parts  of  the  Kocky  Moun- 
tain region  have  been  more  or  less  shaped  by  this  means.  Moreover,  scratches 
made  by  drifted  sand,  long  since  noticed  on  the  glass  of  windows  on  Cape 
Cod,  have  been  observed  in  Maine  where  it  is  not  arid  (G.  H.  Stone,  1886). 
In  arid  parts  of  India,  according  to  Mr.  R.  D.  Oldham,  they  differ  from 
those  of  glaciers  in  being  deepest  at  the  end  facing  the  wind. 

Eolian  denudation  has  its  best  examples  in  the  Egyptian  and  other  true 
deserts  where  the  annual  fall  of  water  is  very  small.  The  following  fig- 
ures of  Egyptian  denuda- 
tion are  from  the  work 
of  J.  Walther  (1891), 
which  treats  the  subject 
with  great  fullness  and 
gives  many  illustrations, 
after  personal  observa- 
tions. The  differences  in 
hardness 'of  the  layers  de- 
Southwest  end  of  Mokkatam.  Walther.  termmes  the  rate  of  wear 

and  leads   to   nearly  the 

same  forms  that  are  produced  by  running  water.  In  Fig.  155  the  beds  are 
Eocene  limestone  and  other  kinds.  In  Fig.  156  Cretaceous  beds  are  upturned, 
and'  the  harder  limestone  caps  each  elevation.  The  deflation  leaves  silicified 
fossils  (Exogyra  and  Corals)  projecting  over  the  surface,  as  in  Fig.  156. 


THE   ATMOSPHERE   AS   A   MECHANICAL   AGENT. 


161 


Other  views  in  Mr.  Walther's  book  represent  deep  excavations  in  nearly 
vertical  bluffs,  sometimes  in  regular  alternation  with  narrow  columns  —  the 
latter  the  part  which  descending  solutions  of  some  kind  (perhaps  calcareous 
or  ferruginous)  had  hardened;  often  they  are  very  irregular  in  form. 

A  blast  of  sand  propelled  by  steam  is  now  employed  (after  Nature's  sug- 
gestion) in  grinding  and 

carving  glass,  gems,  and  15^. 

even  granite.  Glass  cov- 
ered by  lace-work,  or  by 
paper  having  open  pat- 
terns cut  in  it,  is  rapidly 
worn  where  its  surface  is 
exposed,  while  the  lace  or 
paper,  owing  to  its  yield- 
ing before  the  sand,  shows 
scarcely  any  effect  of  the 
blast.  Large  cornices  and 
mouldings  of  granite  are  shaped  by  a  blast  of  steam  and  sand. 

Thoulet,  of  Paris,  has  investigated  the  effects  of  air-blast  abrasion  (1887) 
and  found,  besides  other  results,  that  moist  rock  abrades  most  easily,  and 
that  the  effect  is  small  if  the  surface  struck  has  a  dip  of  less  than  60°. 


Upturned  Cretaceous  beds  near  Abu  Roasch.    Walther. 


TRANSPORTATION  AND  DEPOSITION. 

The  deep  deposits  of  earth  over  ancient  monuments  in  Eome  and  other 
old  cities  is  largely  a  result  of  eolian  transportation.  The  most  extensive 
drift-sand  deposits  occur  over  arid  areas  where  there  is  little  or  no  vegetation 
to  fasten  down  the  sands,  and  where  nearly  all  the  year  through  the  work  is 
going  on.  But  the  best  known  are  those  of  windward  shores  where  fronted 
by  long  beaches.  The  sands  of  seabeaches  often  extend  out  long  distances 
in  the  shallow  waters.  The  breakers  come  in  sand-laden,  to  throw  the  sand 
up  the  beach,  and  in  ordinary  weather  the  beach  takes  the  whole.  But 
storm-winds  carry  the  sands  from  the  breakers  and  the  beach  over  the  low 
surface  beyond  and  pile  it  into  ridges,  often  making  a  series  of  parallel  sand- 
drifts.  The  sand  keeps  moving  landward  with  each  season  of  storms,  unless 
stopped  by  steep  declivities,  or  by  vegetation  whose  encroachment  is  favored 
by  moist  soil ;  and  sometimes  it  drifts  up  the  sea-border  hills  to  heights  of 
100  to  200  feet.  The  surfaces  of  drifted  sands  are  often  covered  with 
ripple-marks. 

The  effects  are  greatest  (1)  where  the  sands  are  fine,  and  most  purely 
siliceous  and  therefore  incoherent ;  (2)  where  the  coasts  are  well  open  to 
the  winds  ;  (3)  in  regions  exposed  to  the  most  violent  storms ;  and  (4)  espe- 
cially on  projecting  points  where  the  work  is  carried  on  in  succession  by  the 
winds  of  both  sides  of  a  rotary  storm,  and  by  storms  of  different  directions. 
Ordinary  winds  have  little  effect,  and  hence  on  the  Pacific  coral  islands  the 
DANA'S  MANUAL — 11 


162  DYNAMICAL   GEOLOGY. 

drift-hills  of  projecting  capes  are  seldom  over  30  feet  high;  while  at  the 
Bermudas  and  Bahamas,  within  the  belt  of  Atlantic  cyclones  whose  winds 
have  often  a  velocity  of  60  to  90  miles  an  hour,  the  sands  cover  great  sur- 
faces, are  sometimes  quite  coarse,  and  make  ridges  100  to  230  feet  in  height. 
The  highest  drift  ridges  are  on  the  side  which  receives  the  winds  of  the  first 
half  of  the  cyclone. 

On  the  south  side  of  Long  Island,  drift-sand  ridges  extend  along  for  a  hun- 
dred miles  and  vary  in  height  from  5  to  40  feet.  The  coast  of  New  Jersey, 
down  to  the  Chesapeake,  and  other  coasts  farther  south,  are  similarly  fronted  by 
sand-hills.  Similar  hills  occur  also  on  the  east  side  of  Lake  Michigan,  where 
they  reach  a  height  of  100  to  200  feet;  they  are  215  feet  high  at  Grand 
Haven,  and  30  to  93  near  New  Buffalo.  In  Norfolk,  England,  between 
Hunstanton  and  Weybourne,  they  are  50  to  60  feet  high. 

Such  seashore  driftings  are  a  means  of  recovering  lands  from  the  sea. 
The  sea  first  makes  the  sand-flats  or  beaches,  and  the  winds  do  the  rest. 
Lyell  observes  that,  at  Yarmouth,  England,  thousands  of  acres  of  land  now 
under  cultivation  have  been  thus  gained  from  a  former  estuary. 

The  drift-sand  also  encroaches  on  fertile  lands,  forests,  and  villages. 
Such  regions  of  encroaching  sands  are  called  dunes.  On  Lake  Michigan,  as 
Professor  Winchell  states,  the  sands  are  continually  shifting  with  the 
winds;  at  Grand  Haven  and  Sleeping  Bear,  the  forest  has  become  sub- 
merged, and  "  presents  the  singular  spectacle  of  withered  tree-tops  pro- 
jecting a  few  feet  above  a  waste  of  sands."  The  land  at  this  place  is 
extending  lakeward,  through  the  wear  and  contributions  of  the  arenaceous 
shore  rocks.  Near  Seven-mile  Beach,  on  the  New  Jersey  coast,  in  1885,  the 
dune,  40  feet  high,  had  encroached  on  a  dense  forest  to  such  an  extent  that 
"the  tree-tops  projected  above  its  sands  like  the  heads  of  drowning  men 
above  the  waves."  (F.  J.  H.  Merrill,  1890.)  By  such  means,  not  only 
bones,  shells,  tree-trunks,  become  the  fossils  of  sand-heaps,  but,  in  the 
existing  age,  as  in  Egypt,  even  monuments,  temples,  and  cities. 

1.  Characteristics  of  wind-drift  or  eolian  formations.  —  The  sands  of  wind- 
drifts,  although  deposited  by  blasts  of  wind,  make  thin  and  regular  layers 
over  the  sand-fields  and  the  surfaces  of  the  rising  ridges,  producing  a  stratic- 
ulate  structure  about  as  coarse  as  that  of  common  alluvial  clays,  parallel 
with  the  successive  surfaces  of  the  ridge.  But  such  ridges  are  liable  to 
be  cut  off  on  one  side  or  the  other  by  the  most  violent  of  gales ;  and  then 
deposition  from  the  winds  goes  on  over  a  new  outer  surface.  By  repetitions 
of  such  catastrophes,  and  continued  depositions,  the  quaquaversal  dip  of  the 
wind-drift  structure,  represented  on  page  93  (Fig.  63),  is  produced.  The 
mode  of  formation  and  straticulate  structure  of  sand-drifts  is  well  illustrated 
in  snow-drifts,  which  are  a  result  of  like  wind-drift  action.  As  snow  drifts 
readily  into  heaps  and  ridges,  wherever  there  is  an  obstacle  however  small, 
so  it  is  with  sand.  Flat  or  level  surfaces  are  the  exception  in  such  regions. 

The  drift  ridges  of  coral  sand  or  shell  sand  readily  consolidate,  and  show 
well  the  varying  directions  of  the  straticulation,  as  at  the  Bermudas, 


THE   ATMOSPHERE   AS   A   MECHANICAL   AGENT.  163 

Bahamas,  Key  West   and  elsewhere   on  the  Florida  Banks,  and  also   on 
Oahu  and  other  Hawaiian  Islands. 

2.  Eolian  transportation  of  volcanic  ashes.  — The  transportation  of  volcanic 
ashes  usually  takes  place  without  drifting,  and  the  bedding,  therefore,  is 
commonly  horizontal.     In  1812,  ashes  were  carried  from  a  volcano  on  St. 
Vincent  to  Barbados,  60  to  70  miles;   and  in  1835,  from  the  volcano  of 
Coseguina  in  Guatemala  to  Jamaica,  a  distance  of  800  miles.     In  1883,  the 
dust  from  the  volcano  of  Krakatoa,  an  island  just  west  of  Java,  was  thrown 
to  a  height  of  50,000  feet,  according  to  Verbeck,  and  continued  to  be  pro- 
jected for  36  hours;  and  it  is  supposed  that  the  ashes  made  the  circuit  of 
the  globe,  and  were  the  cause  of  the  sunset  glows  of  the  following  autumn. 
The  bottom  of  the  Pacific  has  been  found  to  be  very  generally  covered  with 
volcanic  ashes  derived  from  its  many  volcanoes. 

3.  Eolian  transportation  of  living  species  or  their  relics.  —  A  tornado  that 
becomes  what  is  known  as  a  "  water-spout "  over  a  large  river  or  lake,  carry- 
ing up  at  its  center  great  quantities  of  water,  will  take  up  the  ova  and 
smaller  life  of  the  waters,  and  transfer  them  to  other  places,  and  may  thus 
contribute  new  species  to  distant  lakes  or  rivers.     Land  Birds  and  Insects 
are  sometimes  drifted  far  out  to  sea,  and  so  reach  oceanic  islands,  and  some- 
times in  the  case  of  Birds  another  continent.     Seeds  of  many  kinds  go  with 
the  winds.    A  Spider  of  the  ballooning  kind,  Sarotes  venatorius,  has  probably 
traveled  around  the  globe,  according  to  H.  C.  McCook,  crossing  oceans  and 
continents,  and  thus  has  gained  a  world-wide  distribution.     A  related  species 
is  reported  by  Darwin  as  suddenly  appearing  on  the  rigging  of  the  "  Beagle  " 
60  miles  from  the  land. 

Showers  of  grayish  and  reddish  dust  sometimes  fall  on  vessels  in  the 
Atlantic  off  the  African  coast,  and  over  southern  Europe  (producing,  when 
they  come  down  with  rains,  "blood-rains"),  the  particles  of  which,  as  first 
shown  by  Ehrenberg,  are  largely  microscopic  organisms.  The  figures  on 
the  following  page  represent  the  species  from  a  single  shower,  near  Lyons, 
on  October  17,  1846.  The  whole  amount  which  fell  was  estimated  by 
Ehrenberg  at  720,000  pounds;  and  of  this,  one  eighth,  or  90,000  pounds, 
consisted  of  these  organisms. 

The  species  figured  by  Ehrenberg  (Passat- Staub  und  Blut-Regen,  4to,  1847,  and 
Amer.  Jour.  8ci.,  II.  xi.  372),  include  39  species  of  siliceous  Diatoms  (Fig.  157,  1-65);  25 
of  what  he  calls  Phytolitharia  (Fig.  157,  66-104),  besides  8  Rhizopods.  The  following  are 
the  names  of  the  Diatoms  : 

Nos.  1,  2,  Melosira  granulata;  3,  M.  decussata;  4,  M.  Mar  chic  a ;  5-7,  M.  distans ; 
8,  9,  Coscinodiscus  atmosphericus ;  10,  Coscinodiscus  (?)/  11,  Trachelomonas  levis;  12, 
Campylodiscus  clypeus  ;  13-15,  Gomphonema  gracile  ;  16,  17,  Cocconema  cymbiforme; 
18,  Cymbella  maculata ;  19,  20,  Epithemia  longicornis;  21,  22,  E.  longicornis;  23,  E. 
Argus;  24,  E.  longicornis;  25,  Eunotia  granulata  (?)  ;  26,  E.  zebrina  (?)  ;  27,  Him- 
antidium  Monodon  (?);  28-32,  Eunotia  amphioxys;  33,  34,  Epithemia  gibberula;  35, 
Eunotia  zebrina  (?)  ;  36,  E.  zygodon  (?)  ;  37,  Epithemia  gibba ;  38,  Eunotia  tridentula; 
39,  E.  (?)lavis;  40,  Himantidium  arcus ;  41,  42,  Tabellaria;  43,  Odontidium  (?) ; 
44,  Cocconeis  lineata ;  45,  C.  atmospherica ;  46,  Navicula  bacillum ;  47,  N.  amphioxys  ,* 


164 


DYNAMICAL  GEOLOGY. 


157. 


37 

"-"""iinniintinnrJl 

60  63 

inmiV.l....U..I......,, U....U .., U ..JJ;--.U.A 

^l-^^  ^  T       67 


Diatoms  and  other  microscopic  organisms  of  a  dust  shower.    Ehrenberg. 


THE   ATMOSPHERE   AS   A   MECHANICAL   AGENT.  165 

48,49,  N.  semen;  50,  N.  serians ;  51,  Pinnularia  borealis;  52,  P.  mridula ;  53,  P. 
viridis;  54,  Mastogloia  (?);  55,  Pinnularia  cequalis  (?);  56,  Surirella  craticula  (?); 
57,  58,  Synedra  ulna;  59,  Odontidium  (?)  ;  60,  Fragilaria  pinnata  (?)  ;  61,  Mastogloia 
(?);  62-65,  doubtful. 

A  shower  which  happened  near  the  Cape  Verd  Islands,  and  is  described  by  Darwin, 
had  by  his  estimate  a  breadth  of  more  than  1600  miles,  —  or,  according  to  Tuckey,  of 
1800  miles,  —  and  reached  800  or  1000  miles  from  the  coast  of  Africa.  These  numbers 
give  an  area  of  more  than  a  million  square  miles. 

In  1755,  there  was  a  "blood-rain"  near  Lago  Maggiore,  in  northern  Italy,  covering 
about  200  square  leagues,  which  made  an  earth  deposit  in  some  places  an  inch  deep ;  if 
averaging  two  lines  in  depth,  the  amount  for  each  square  mile  would  equal  2700  cubic 
feet.  The  red  color  of  the  "blood-rain"  is  owing  to  the  presence  of  some  red  oxide  of 
iron. 

Ehrenberg  enumerates  a  large  number  of  these  showers,  citing  one  of  the  earliest 
from  Homer's  Iliad ;  and  among  those  whose  deposits  he  examined  he  distinguished  over 
300  species  of  organisms.  The  species,  so  far  as  ascertained  by  him,  are  not  African,  and 
15  are  South  American.  The  zone  in  which  these  showers  occur  covers  southern  Europe 
and  northern  Africa,  with  the  adjoining  portion  of  the  Atlantic,  and  the  corresponding 
latitudes  in  western  and  middle  Asia. 


ANGLE  OF  REST  OF  FALLING  SAND  OK  GRAVEL. 

The  angle  of  rest  in  falling  sand  or  gravel  varies  with  the  size,  density, 
shape,  and  smoothness  of  the  grains ;  and  also  with  the  amount  of  moisture 
or  water  present  among  them,  little  moisture  causing  adhesion  of  grains, 
much  water  producing  a  flowing  mud.  With  no  friction,  as  is  essentially  the 
fact  in  the  case  of  the  particles  of  a  liquid,  like  water,  the  angle  is  null ; 
with  ordinary  dry  sand,  30°  to  35° ;  with  ordinary  volcanic  cinders,  33°  to  40°. 

Instructive  experiments  may  be  made  by  inserting  vertically  a  graduated  rod  at  the 
center  of  a  circular  board  graduated  similarly  from  its  center  outward,  and  then  dropping 
over  the  board  about  the  rod  sand  of  different  kinds,  the  ratio  of  height  to  radius  giving 
the  angle.  The  author  obtained  in  this  way  for  dry  angular  quartz  sand  about  0-005  inch 
in  radius,  the  angle  35°  20'  to  36°  30' ;  for  iron-sand,  of  like  fineness,  33°  10'  to  33°  40' ; 
for  new  (untarnished)  shot,  No.  10,  very  fine,  20°  12' ;  same,  No.  4  (coarser),  27°  50' ; 
same,  No.  3  (buck-shot),  29°  40'  ;  and  with  tarnished  shot,  a  higher  angle. 

When  deposition  is  around  a  center,  or  pericentric,  the  resulting  form  is 
approximately  conical,  varying  with  irregularities  in  deposition  through  the 
winds  and  other  causes. 

ATMOSPHERIC  PRESSURE. 

Variations  in  atmospheric  pressure,  which  may  amount  to  two  inches 
of  the  barometer  in  a  few  hours,  or  half  as  many  pounds  per  square  inch, 
are  supposed  to  influence  the  resistance  of  the  earth's  crust  to  earthquake 
movements,  and  to  volcanic  eruptions.  The  tide-like  movements  in  large 
lakes  are  attributed  to  other  causes. 


166  DYNAMICAL   GEOLOGY. 

IV.    WATER  AS  A  MECHANICAL  AGENT. 

(1)  General  sources  of  activity.  —  (a)  Water  does  mechanical  work  in 
each  of  its  three  states,  the  liquid,  solid,  and  gaseous  state  (or  that  of  vapor). 
Only  the  first  and  second  states  are  here  considered,  the  third  coming  more 
conveniently  under  the  head  of  Heat.  In  the  liquid  state  it  constitutes 
rivers,  lakes,  oceans;  in  the  solid,  snow,  ice-crusts,  glaciers,  and  icebergs. 
Unlike  the  aerial  ocean,  it  has  a  defined  upper  surface ;  and  the  basement 
on  which  it  rests  has  usually  no  disturbing  influence. 

(6)  In  rivers,  water  derives  its  energy  from  gravitation ;  it  works  as  it 
falls,  and  arrives  at  its  zero  of  action  on  reaching  the  lowest  level  to  which 
it  can  fall.  It  reaches  only  temporary  or  approximate  zeros  in  lakes,  except 
when  the  lakes  are  like  the  ocean  in  having  no  outlet.  Winds  make  rela- 
tively feeble  currents  and  waves  in  large  rivers. 

(c)  In  the  ocean,  water  has  three  prominent  working  agencies:   (1)  the 
tidal  wave ;    (2)  the  wind-waves  and  currents,  both  the  regular  winds,  like 
the  trades,  and  the  winds  of  storms,  each  producing  waves  and  also  currents 
of  greater  or  less  depth  and  velocity;   (3)  the  resupply  currents  caused  by 
the  sun's  heat,  which  in  evaporation  removes  surface  waters,  and,  in  the 
expansion  of  water,  diminishes  its  density.     Gravity  acts  toward  a  restora- 
tion of  the  equilibrium  that  has  been  disturbed,  whether  the  disturbance  be 
due  to  the  tidal  wave,  wind-waves,  currents,  or  heat,  and  in  response  also  to 
changes  in  atmospheric  pressure. 

(d)  Lakes  of  large  size,  like  the  ocean,  have  wind-made  currents  and 
waves,  and  movements  due  to  evaporation,  and  sometimes  appreciable  tidal 
waves  and  currents.     Those  of  small  size  are  often  only  still-water  incidents 
in  the  courses  of  rivers. 

Winds  over  large  rivers  may  slightly  quicken,  or  retard,  the  flow.  Over 
great  lakes,  they  may  make  decided  onward  movements,  which  pile  the  waters, 
tide-like,  on  leeward  shores,  —  as  sometimes  about  Duluth  at  the  western  end 
of  Lake  Superior,  —  occasioning  an  under  current  of  escape.  But  over  the 
ocean  they  are  in  all  parts  a  prominent  source  of  currents,  and  in  the 
tropics,  as  has  been  stated,  the  "  trade  winds  "  originate,  according  to  some 
physicists,  the  Atlantic  and  Pacific  tropical  oceanic  currents. 

(e)  Owing  to  the  earth's  eastward  rotation,  increasing  in  rate  of  surface 
velocity  from  the  pole  to  the  equator  as  the  cosine  of  the  latitude,  flowing 
waters  in  the  northern  hemisphere,  whether  of  rivers  or  the  ocean,  and 
whatever  their  source,  are  thrown  toward  the  right  side  as  they  advance, 
and  in  the  southern  hemisphere  toward  the  left  side.     The  result  is  seen  in 
the  lagging  of  the  Labrador  current  against  the  west  side  of  the  north  Atlan- 
tic; in  a  like  effect  on  the  correlate  current  in  the  north  Pacific;  and  in 
the  eastward  course  of  the  Gulf  Stream  north  of  the  parallel  of  35°.     It  has 
also  been  observed  along  rivers  in  many  parts  of  the  world  where  the  deposits 
intersected  are  earthy,  and  the  pitch  of  the  stream  is  too  small  for  erosion  at 
bottom.     They  are  marked  along  the  great  rivers  of  Siberia  and  European 


WATER   AS   A  MECHANICAL  AGENT.  167 

Russia,  on  others  in  southern  France,  on  the  streams  intersecting  the  low 
land  of  the  Atlantic  border  of  the  United  States  (Kerr),  and  on  those  of 
southern  Long  Island  (E.  Lewis). 

It  is  shown  that  in  streams  the  difference  between  the  surface  and  bottom 
velocity  accounts  for  this  erosion  of  the  right  bank,  with  deposition  at  the 
left,  thereby  making  the  right  steeper  and  placing  the  deepest  part  of  the 
stream  near  it.  The  extremely  slow  transverse  motion  will  be  combined 
with  that  down  stream,  so  that  the  actual  motion  will  make  a  very 
small  angle  with  the  direction  of  the  channel.  (A.  C.  Baines,  Am.  Jour. 
Sci.,  xxviii.  1884.) 

(2)  Kinds  and  methods  of  work.  —  The  kinds  of  work  done  by  the 
mechanical  action  of  waters,  whether  in  rivers,  lakes,  or  oceans,  are  in  a 
comprehensive  way  (1)  Denudation;  (2)  Transportation;  (3)  Deposition 
of  the  transported  material,  making  usually  stratified  deposits. 

DENUDATION. 

Denudation  is  going  on  wherever  any  rock  materials  or  rocks  are  within 
reach  of  moving  waters.  It  is  called  erosion  or  excwvation,  when  the  work  is 
the  making  of  valleys,  and  degradation,  when  it  is  the  wearing  down  of  hills 
or  mountains.  But  the  term  denudation  covers  both  processes.  Another 
style  of  work  under  it  is  that  of  planation,  or  the  making  of  flat  surfaces  by 
the  shearing  action  of  spreading  waters,  and  by  deposition  up  to  the  surface, 
or  to  a  common  level.  The  worn  material  derived  from  the  wear  of  rocks  is 
called  detritus,  because  made  by  wear;  and  also  after  deposition,  sediment, 
because  deposited  usually  from  waters.  Sedimentary  rocks  derive  thence 
their  name.  Silt,  the  finest  of  mud,  occurring  in  the  bottom  of  estuaries  and 
elsewhere,  and  ooze,  soft,  sticky  mud,  are  extreme  results  of  the  grinding 
process.  The  term  deposit  is  a  general  one  for  an  accumulation  made  by 
any  natural  method. 

Denudation  depends  for  its  effects  on  the  varieties  and  conditions  of  the 
rocks  subjected  to  it  not  less  than  on  the  powers  of  the  agent,  water.  It  is 
facilitated  not  only  (1)  by  softness  or  fragility  of  terranes,  but  also  by 
(2)  their  subdivision  into  thin  layers ;  (3)  a  loose  junction  of  layers ; 
(4)  alternation  of  yielding  layers  with  firmer  layers ;  (5)  vertical  joints  or 
fractures,  and  especially  multitudes  of  surface  cracks  or  rifts.  (6)  Boldness 
in  position  is  also  favorable ;  for  high  bluff  fronts  feel  the  force  of  blows  of 
water  proportionally  to  their  verticality,  and  also  have  gravity  to  aid  in 
removing  loosened  material,  and  to  produce  rendings  where  water  descends 
in  vertical  crevices.  (7)  Moreover,  angular  concavities  or  cavernous  open- 
ings and  projecting  points  in  walls  give  the  waters  great  advantage.  (8)  A 
horizontal  position  in  the  bedding  of  cliffs  or  walls  is  especially  favorable, 
because  a  little  removal  below  undermines,  and  may  cause  great  downfalls ; 
and,  besides,  walls  and  cliffs  are  thus  kept  vertical,  for  the  long  continuation 
of  the  work.  (9)  Above  all,  denudation  is  facilitated  by  the  weakened  con- 


168  DYNAMICAL   GEOLOGY. 

dition  of  rocks,  due  to  decay  through  chemical  methods,  and  to  the  superficial 
riftings  and  fractures  attending  chemical  changes,  organic  growths,-  freezing, 
and  the  alternating  of  cold  with  heat  occasioned  by  the  sun. 

The  methods  of  denudation  are  (1)  by  water-strokes,  or  the  simple  impact 
of  water;  (2)  by  abrasion,  which  includes  (a)  wear  of  rocks  by  means  of 
the  stones  and  earth  carried  or  thrown  against  rocky  surfaces ;  and  (b)  wear 
of  transported  stones  or  grains  by  their  mutual  friction  or  corrasion.  By 
these  means  much  of  the  shaping  of  the  earth's  surface  and  the  trituration 
of  rocks  to  earth  has  gone  forward.  Abrasion  becomes  a  shearing  action  in 
planation  and  terrace-making. 

1.  Impact  of  water  simply.  —  In  the  flow  over  a  smooth  surface  of  rock 
pure  water  has  no  abrading  effect.     But  when  thrown  in  masses,  in  the  form 
of  plunging  waves  or  torrents,  into  cavities  of  rocky  bluffs  or  against  bold 
projections,  great  results  may  be  produced.     Blocks  of  many  tons'  weight 
along  a  shore,  if  resting  on  a  surface  but  slightly  inclined  toward  the  deeper 
water,  will  slip  downward  with  each  stroke. 

The  force  of  the  impact  of  flowing  water  is  expressed  in  pounds,  by  the  general 
equation  P  =  0-9702wsv2,  in  which  v  is  the  velocity  in  feet  per  second,  s  is  the  greatest 
transverse  section  of  the  body  in  square  feet,  n  a  coefficient  varying  with  the  form  of  the 
body,  the  value  being  ascertained  for  any  particular  form  by  trials ;  and  0-9702  is  the 
quotient  from  dividing  the  weight  of  one  cubic  foot  of  water  (62^  pounds)  by  2  g  (p.  174). 
Supposing  the  greatest  transverse  area  to  be  1  foot :  for  a  simple  plate  the  value  of  n  is 
1-86;  for  a  cube,  1-46;  for  a  sphere,  0-51 ;  for  some  rounded  forms,  only  0-25.  If  the 
hemispherical  end  of  a  cylinder  faces  the  current,  the  impact  is  half  less  than  if  the  flat 
end  were  in  front.  In  accordance  with  the  above,  the  force  of  impact  against  a  flat  plate 
a  foot  square,  in  a  current  of  5  miles  an  hour  (or  7£  feet  per  second),  will  be  nearly 
100  pounds  ;  in  one  of  20  miles  an  hour  (4  times  5),  16  times  that  for  5  miles,  and  so  on. 
On  the  other  hand,  if  the  surface  struck  is  a  hemispherical  concavity,  the  impact  would 
be  very  much  greater  than  for  a  flat  surface,  the  value  of  n  being  about  2  for  a  hollow 
hemisphere  with  the  concavity  to  the  current.  The  principle  is  illustrated  in  the  connec- 
tion between  form  and  resistance,  or  form  and  velocity,  in  a  boat. 

These  results  of  experiment  and  mathematical  calculation  show  that  while  it  is  not 
possible  to  measure  the  force  exerted  in  the  movements  of  a  river,  the  concavities  and 
deep  recesses  or  channels  among  the  rocks  along  the  sides  of  a  rapid  stream  afford  an 
opportunity  for  effective  blows. 

2.  Abrasion  ;  Corrasion.  —  The  transported  sand  and  gravel  which  is  car- 
ried by  water  against  the  rocks  within  reach  acts  like  the  emery  of  an  emery 
wheel,  yet  only  under  slight  pressure.     The  particles,  and  especially  the 
pebbles  or  stones,  that  are  thrown  by  violent  torrents  against  the  surfaces 
of  the  solid  rock,  work  more  effectively,  but  less  constantly.     In  a  current  of 
given  velocity  the  larger  stones  carried  abrade  more  rapidly  than  the  smaller. 
At  the  same  time  the  transported  particles  or  stones,  whether  in  rivers  or 
on  seashores,  are  wearing  one  another,  and  this  corrasion  tends  to  reduce  the 
material  to  that  fine  impalpable  state  in  which  even  slow-moving  waters  will 
transport  them. 


WATER    AS   A   MECHANICAL   AGENT.  169 

The  coarser  grains  transported  by  the  water  suffer  the  most  in  cor- 
rasion,  a  grain  a  tenth  of  an  inch  thick  wearing  10  times  as  fast  as  one 
a  hundredth  of  an  inch,  and  an  inch  pebble  losing  more  in  transportation  a 
few  hundred  yards  than  a  grain  of  sand  of  a  thousandth  of  an  inch  in  drift- 
ing for  100  miles  (Sorby,  1880).  Angular  fragments  of  granite  lose  more 
by  corrasion  than  rounded  fragments.  Ordinary  sand-grains  become  rounded 
in  a  similar  manner ;  but  those  of  the  finest  quartz-flour  from  glaciers  (as 
that  giving  the  milky  tint  to  the  Rhine  at  Strassburg)  remain  angular, 
instead  of  becoming  corraded  (Daubree,  1879). 

Shales  and  soft  sandstones  yield  easily  to  abrading  agents ;  hard  sand- 
stones and  quartzytes  much  less  so ;  basalts,  granites,  very  slowly,  unless  the 
wear  is  promoted  by  previous  decay.  Limestones  are  eroded  easily  because 
the  material  is  soft  and  the  waters  may  dissolve  as  well  as  wear  away. 

Abrasion  assorts  in  proportion  to  hardness.  The  softer  materials  first 
yield,  leaving  the  harder.  When  granitic  sands,  made  of  quartz,  mica,  and 
feldspar,  are  exposed  to  beach  or  river  action,  the  mica  first  floats  off,  because 
in  thin  scales;  next  the  feldspar  is  reduced  in  the  corrasiou  to  fine  earth  and 
is  borne  away ;  and  the  hard  quartz  is  left  in  grains.  Thus  at  the  same  time, 
out  of  the  same  sand  are  made  a  bed  of  quartz  sand,  for  a  sandstone,  and  not 
far  off  it  may  be  an  argillaceous  or  mud-like  bed,  good  for  forming  a  shale. 

Rivers  and  beaches  are  thus  ever  at  work  when  materials  of  the  right  kind 
are  at  hand.  Where  the  flood-waters  of  a  river,  or  the  tidal-waters  of  the 
ocean,  flow  widely  over  shelving  shores  and  bordering  flats  with  little  depth, 
the  surface  water  as  it  moves  onward  is  like  a  horizontally  cutting  blade ; 
and,  while  admitting  of  deposition  up  to  its  level,  it  shears  off  the  surface 
with  remarkable  evenness,  making,  by  this  process  of  planation,  flat  shore- 
platforms  and  flood-grounds  or  terraces,  such  as  occur  along  many  river  val- 
leys and  sea  borders  ;  and  the  plains  are  often  at  heights  which  make  them 
evidence  of  ancient  water  levels. 

TRANSPORTATION  AND  DEPOSITION. 

The  rate  of  denudation  depends  largely  on  the  velocity  of  the  transporting 
water.  The  transporting  power  increases  as  the  sixth  power  of  the  velocity 
(Hopkins,  1844).  With  twice  the  velocity  the  weight  of  transportable  par- 
ticles is  increased  64  times ;  or,  if  the  particles  are  of  the  same  specific 
gravity,  the  transportable  particles,  if  the  velocity  is  doubled,  may  have  four 
times  the  diameter,  or  64  times  the  weight. 

The  stones,  unless  they  have  the  specific  gravity  of  water,  are  moved 
mainly  along  the  bottom ;  and  being  continuously  under  the  action  of  gravity, 
the  movement  of  each,  like  that  of  a  projected  cannon-ball,  is  in  a  long 
curve.  It  makes  a  series  of  leaps,  rising  from  the  bottom  and  returning  to 
it, — the  length  of  the  curve  varying  with  the  velocity  and  the  specific 
gravity.  The  finest  of  sediment  remains  long  in  suspension,  giving  a  cloudi- 
ness to  waters ;  and  it  has  been  suggested  that  a  partial  alteration  of  the 


1TO  DYNAMICAL   GEOLOGY. 

feldspar  to  a  hydrous  alumina  silicate  is  the  cause.  This  finest  of  sediment 
falls  on  incipient  freezing  (Brewer,  1883).  Very  thin  particles,  like  scales 
of  mica,  sink  slowly,  because  the  rate  is  that  of  particles  (of  the  same 
density)  having  a  diameter  equal  to  the  thickness  of  the  scales.  They  are 
hence  widely  scattered  by  transporting  waters. 

Transportation  assorts  in  proportion  to  size  and  specific  gravity.  —  In 
accordance  with  the  ratio  of  transportation  to  velocity,  it  is  found,  supposing 
the  material  to  be  alike  in  specific  gravity,  that  a  current  of  4  miles  an 
hour  will  carry  along  stones  21  inches  in  diameter ;  of  2  miles,  pebbles  of  0-6 
inch  in  diameter ;  of  f  mile,  fine  sand  about  0-064  inch  in  diameter ;  of  -J-  mile, 
fine  earth  or  clay,  the  particles  0-016  inch  in  diameter.  Consequently, 
materials  will  be  arranged  over  the  bottom  by  velocity  of  flow,  the  coarser 
dropping  first,  the  finer  at  greater  or  less  distances  beyond,  and  the  finest 
floating  on  to  other  places  of  deposition. 

Again,  sands  of  like  size  but  varying  specific  gravity  will  be  assorted  on 
the  same  principle,  iron  sands  (G  =  5)  being  left  behind  where  the  current 
is,  only  sufficient  to  carry  on  garnet  sand  and  other  lighter  kinds ;  and  garnet 
sand  (G  =  3-6),  where  the  quartz  sand  (G  =  2'6)  is  still  kept  in  move- 
ment, so  that  several  sorts  of  deposits  may  form  by  varying  rates  of  flow. 
If  gold  dust  (G  =  18  to  20)  were  in  the  waters,  it  would  drop  long  before 
the  iron  sand.  The  principle  is  used  in  ordinary  gold  washings. 

In  drawing  inferences  as  to  rate  of  flow  during  deposition  from  the 
fineness  or  coarseness  of  deposits,  there  is  need  of  caution,  because  flowing 
waters  do  not  "  scour  "  at  the  rates  mentioned,  unless  the  materials  are  quite 
loose.  Very  slight  compacting  at  surfaces  will  hold  the  sands  and  earth 
down.  Let  any  causes  stir  up  the  bottom,  then  the  principle  works  well ; 
and  in  these  modern  times  steamers  up  and  down  rivers,  bays,  and  coasts, 
often  occasion  that  stirring  which  favors  scour,  to  the  benefit  of  navigation. 
Professor  Verrill  has  remarked  that  the  shells  broken  up  by  fishes  over  the 
ocean's  bottom  make  loose  material  easy  of  transportation  by  the  Gulf 
Stream. 

An  important  exception  to  this  relation  between  size  of  particles  and 
hydraulic  value,  noticed  and  made  the  subject  of  special  investigations  by 
E.  W.  Hilgard,  arises  from  the  tendency  of  the  finer  kinds  of  sediment  in 
fresh  water,  if  the  water  is  not  absolutely  quiet,  to  agglomerate  their  parti- 
cles, when  not  over  1  mm.  in  diameter,  into  larger  particles,  or  to  flocculate, 
as  he  terms  the  process,  and  so  take  the  hydraulic  value  of  coarser  sediments. 
He  shows  that  fine  river  deposits  consist  largely  of  such  flocculated  particles, 
and  that  the  fitness  of  soils  for  tillage  depends  largely  on  the  porous  condi- 
tion thus'  derived. 

Some  characteristics  of  water.  —  (a)  A  cubic  foot  of  pure  water  at  62°  F.  weighs 
436,495  grains,  which  equals  62-355  pounds,  or  nearly  1000  ounces  avoirdupois  —  28,315 
grams.  The  soluble  impurities  of  ordinary  river  water  are  0-000186  of  their  weight. 
(Murray.) 

Under  a  pressure  of  1  atmosphere,  water  boils  at  212°  F.  =  100°  C.  j  and  under  45 
atmospheres,  at  510-6°  F.  =  265-9°  C. 


WATER   AS   A    MECHANICAL   AGENT.  171 

(by  When  water  freezes,  it  crystallizes  in  ttie  hexagonal  system :  either  in  slender 
prisms  ;  in  compact  aggregations  of  prisms,  making  a  mass  of  ice  ;  in  small  6- rayed  stars, 
as  in  snow ;  or  in  feathery  forms,  as  in  the  frost  over  windows  and  pavements  in  winter. 
In  the  thick  crusts  made  over  water  in  cold  seasons,  the  prismatic  structure  is  vertical 
except  in  a  thin  upper  layer :  a  fact  proved  by  means  of  polarized  light. 

(c)  The  density  of  water  is  greatest  at  39-2°  F.  =  4°  C.    From  this  point,  it  decreases, 
or  the  water  expands,  as  the  temperature  falls  to  32°  F.,  the  freezing-point,  and  as  the 
temperature  rises  above  39-2°  F.     The  specific  gravity  of  ice,  relatively  to  water  as  the 
unit,  is  0-9178  ;  and  hence  11  volumes  of  ice  make  about  10  of  water. 

(d)  The  increase  of  bulk  of  water  when  it  becomes  vapor,  which  it  may  at  any  tem- 
perature, is,  under  ordinary  pressure,  1700  times  ;  and  hence  1  cubic  inch  of  water  yields 
about  1  cubic  foot  of  steam  or  vapor.     The  density  of  vapor  at  212°  F.,  taking  air  as  1, 
is  0-6235. 

In  the  further  consideration  of  the  subject  of  water  as  a  mechanical  agent, 
the  natural  subdivisions  adopted  are :  — 

1.  FRESH  WATERS;   including  especially  Kivers,  Lakes,  and  Subterra- 
nean Waters. 

2.  The  OCEAN. 

3.  FROZEN  WATER,  or  Ice,  Glaciers,  Icebergs. 


I.    FRESH   WATERS. 

The  several  topics  are  the  following :  — 

1.  Gathering  of  water  into  rivers  and  lakes. 

2.  Working-power  of  rivers. 

3.  Methods  and  results  of  denudation. 

4.  Transportation  and  deposition. 

5.  Special  points  in  fluvial  history. 

6.  Subterranean  waters. 

GATHERING  OF  WATER  INTO  RIVERS  AND  LAKES. 

The  fresh  waters  of  the  land  come  from  the  vapors  of  the  atmosphere,  and 
these  chiefly  from  the  ocean,  but  largely  also  from  the  waters  and  moisture 
of  the  land  and  its  vegetation. 

The  conditions  favoring  the  making  of  large  streams  are  as  follows:  — 

1.  Large  drainage  areas,  with  high  mountains  on  their  borders.  —  The  cold 
summits  of  mountains  are  condensers  of  moisture,  and  sometimes  perpetual 
condensers,  when  the  country  below  is  dry ;  and  their  elevation  gives  force 
to  the  descending  waters.  Long  slopes  and  combinations  of  those  of  differ- 
ent mountain  ridges  and  ranges  make  the  great  rivers.  In  the  Americas  the 
mountain  chains  of  the  opposite  sides  of  the  continent  contribute  toward 
the  Mississippi,  St.  Lawrence,  Mackenzie,  Amazon,  and  La  Plata;  and  so 
it  is  in  the  Orient.  Short  slopes  hurry  off  the  waters  to  the  sea  and  make 
small  drainage  areas. 


172  DYNAMICAL   GEOLOGY. 

2.  Abundant  precipitation.  —  The  annual  fall  of  rain  (and  snow)  over  the 
Mississippi  drainage  area  is,  for  the  eastern,  or  Appalachian  part,  40  to  50 
inches ;  for  the  much  larger  west-central  part,  west  of  the  Mississippi  River, 
20  to  25  inches  ;  for  the  western  part,  among  the  summits  of  the  Eocky 
Mountains,  25  to  30  inches.     In  the  vast  Amazon  drainage  area  the  annual 
precipitation  exceeds  50  inches  both  on  the  west  and  north,  and  is  every- 
where ov^r  25  inches. 

3.  Upward  waste,  or  that  by  evaporation,  small.  —  Under  a  hot  and  dry 
climate,  and  in  the  absence  of  forests,  the  waste  is  great.      The  western 
tributaries  of  the  Mississippi  lose  a  large  part  of  the  waters  received  in  the 
mountains  while  descending  the  dry,  bare  eastern  slopes.     Where  the  Nile 
takes  its  rise,  the  annual  precipitation  is  over  50  inches,*  but  it  is  not  more 
than  10  through  the  lower  two  thirds  of  its  course.     An  extravagant  example 
of  this  waste  is  shown  on  the  map  of  western  Maui,  on  page  179,  where  there 
are  great  channels  in  the  mountains  and  mere  threads  over  the  surface  to  the 
west  where  it  seldom  rains. 

4.  Downward  waste,  or  that  by  gravity  and  soil  absorption  over  the  drain- 
age area,  small.  —  Not  only  loose  sands,  but  also  many  sandstones  are  very 
absorbent ;  and  limestones,  although  nearly  impervious  to  moisture,  are  often 
cavernous,  and  sometimes  swallow  up  rivers.     In  western  New  South  Wales 
the  rivers  take  only  2J  per  cent  of  the  precipitation,  owing  chiefly,  it  is  stated, 
to  the  porosity  of  the  sandstone  of  the  region.     Most  lavas  are  porous  and 
somewhat  cavernous,  but  may  lose  these  qualities  by  infiltration  of  earth 
from  decomposition.     Further,  most  stratified  uncrystalline  rocks  are  loose 
in  bedding,  and  take  off  much  water  along  the  open  spaces  between  the 
layers.     Granite  and  other  crystalline  rocks  make  the  tightest  basins ;  for 
they  absorb  little. 

Frozen  or  icy  ground  is  like  impervious  rock ;  almost  all  the  water  that 
falls  over  it  goes  to  the  rivers.  Moreover,  in  cold  weather  evaporation 
carries  off  but  little.  Hence  come  the  sudden  rise  and  height  of  many 
spring  floods  in  cold-temperate  latitudes. 

In  very  dry  and  warm  climates,  where  the  precipitation  is  reduced  to  a 
few  inches  a  year,  rivers  fail  altogether,  or  flow  only  during  the  short  rainy 
season.  Between  drying  up  under  the  hot  sun  and  soaking  away  in  the 
sandy  soil,  they  are  soon  gone,  and  the  lakes  along  their  courses,  or  receiving 
their  waters,  may  share  their  fate. 

Other  sources  of  loss  in  surface  waters  are  (1)  the  demands  of  vegetable 
and  animal  life ;  and  (2)  the  chemical  combinations  attending  the  decay  of 
rocks  in  which  hydrous  minerals,  as  the  hydrous  iron  oxide  and  clays,  are 
made. 

.  Of  the  water  precipitated,  the  rivers  may  get  45  to  50  per  cent  over  regions 
of  crystalline  rocks,  as  is  true  of  the  Connecticut  River.  In  other  parts  of 
temperate  latitudes  the  amount  is  usually  a  third  to  two  fifths  of  what  falls. 
But  in  warm  latitudes  it  may  be  under  one  tenth.  The  mean  annual  dis- 
charge of  the  Mississippi  River  is  about  25  per  cent  of  the  precipitation ;  it 


WATER   AS   A   MECHANICAL   AGENT.  173 

averages  19 J  trillions  (19,500,000,000,000)  of  cubic  feet,  varying  from  11 
trillions  in  dry  years  to  27  trillions  in  wet  years.  The  Amazon,  in  the 
tropics,  with  a  drainage  area  not  twice  as  large,  carries  to  the  sea  five  times 
as  much  water  as  the  Mississippi. 

The  mean  annual  discharge  of  the  Missouri  River  is  about  3J  trillions,  or  -^  of  the 
amount  of  the  rains  over  the  region.  The  corresponding  amount  for  the  Ohio  is  5  trillions, 
which  is  \  the  amount  of  rain.  (Humphreys  and  Abbot.)  The  Ganges  carries  down  about 
4£  trillions  annually,  and  the  Nile  3£  trillions.  The  rivers  of  England  and  Wales  carry  to 
the  sea  18-3  inches  in  depth  out  of  an  annual  fall  of  about  32  inches. 


WORKING-POWER  AND  ACTION  OF  RIVERS. 

1.  Energy  from  height  of  fall.  —  It  has  been  stated  that  in  rivers  the 
water  works  as  it  falls ;  so  that  the  amount  of  work  done  depends  on  the 
rate  of  fall  along  its  course  to  its  outlet,  and  the  amount  of  water. 

In  the  mountain  stream  the  slope  of  the  water  varies  from  90°,  or  that  of 
a  waterfall,  downward  to  one  degree  and  less.  But  in  the  large  rivers  it 
seldom  exceeds  12  inches  to  a  mile,  and  is  sometimes  but  one  third  this 
amount. 

The  slope  of  the  Mississippi,  from  Memphis  down  (855  m.)  is  4-82  inches 
per  mile  at  low  water;  from  Cairo,  at  the  mouth  of  the  Ohio  (1088  m.), 
6-94  inches  ;  and  above  the  Missouri,  from  its  source,  11  f  inches.  The 
Missouri,  from  its  highest  source  (2908  m.),  descends  about  6800  feet,  or 
28  inches  a  mile ;  but  from  Fort  Benton  to  St.  Joseph  (2160  m.),  about  11 J 
inches  ;  and  below  St.  Joseph  to  the  mouth  (484  m.),  9i.  (From  Humphreys 
and  Abbot.)  The  average  slope  of  the  Amazon  for  3000  miles  from  its 
mouth  is  less  than  an  inch,  the  descent  in  this  distance  being  210  feet ;  of  the 
Lower  Nile,  not  7  inches;  of  the  Lower  Ganges,  about  4.  The  Khone  is  re- 
markable for  its  great  slope,  it  being  80  inches  per  mile  from  Geneva  to  Lyons, 
and  32  inches  below  Lyons.  The  tidal  portions  of  rivers,  which  have  no 
slope  with  the  rising  tide,  have  a  slope  and  a  strong  flow  with  the  ebbing  tide. 

During  high  floods  the  course  of  a  river  is  shortened,  because  the  minor 
bends  are  obliterated  by  the  overflow,  and  where  the  channel  is  broad  and 
open,  the  slope  is  commonly  increased  in  amount  and  uniformity.  Narrows 
between  rocky  bluffs  act  like  a  dam,  and  diminish  the  pitch  above  them, 
often  spreading  the  waters  into  lakes,  while  they  increase  the  pitch  below. 
At  such  narrows  floating  ice  often  makes  obstructions  in  the  spring,  which 
greatly  increase  the  height  of  the  waters.  A  dam  higher  up  the  stream,  that 
obstructs  or  holds  back  the  ice  during  its  break-up,  may  save  large  areas 
from  the  flooding  effect  of  the  narrows.  Narrows  are  sometimes  created  along 
streams  by  encroaching  human  "improvements";  but  a  narrowing  either 
of  a  river's  natural  flood-grounds  or  its  place  of  discharge  may  be  a  source 
of  disaster.  The  water-power  of  the  flooded  river  is  safely  controlled  only 
by  keeping  the  channel  and  outlet  large  enough  to  carry  off  all  the  water  as 
it  comes. 


174  DYNAMICAL   GEOLOGY. 

2.  The  amount  of  work  which  a  body  of  water,  as  that  of  a  lake,  can  theo- 
retically do,  on  its  descent  to  the  level  of  the  sea,  is  equal  to  the  product  of 
the  height  of  the  lake  (h)  into  the  weight  ( W)  of  the  water ;  and  hence  Wh 
is  an  expression  in  foot-pounds  for  the  energy  or  working-power  potentially 
present  in  the  lake.  The  amount  of  energy  in  a  lake  a  fourth  of  a  square 
mile  in'  surface,  10  feet  in  average  depth,  and  400  feet  above  the  sea  level,  is 
1,742,400,000,000  foot-pounds ;  —  a  power  sufficient,  could  it  be  expended 
without  loss,  to  raise  a  mass  of  stone  weighing  about  87,000  tons  to  the  top 
of  a  mountain  10,000  feet  high.  If  now  the  water  were  allowed  to  flow  by  a 
continuous  slope  to  the  sea  level,  without  loss  from  evaporation,  or  from 
resistance  of  any  kind  (such  as  friction,  etc.),  its  velocity  would  increase 
regularly  according  to  the  well-known  law  of  falling  bodies  ;  and,  in  this 
increase  of  rate,  it  would  be  constantly  accumulating  energy  of  motion,  which 
would  be  the  exact  equivalent  of  the  energy  of  position  it  was  losing ;  and 
when  it  reached  the  lower  level  its  velocity  would  be  160  feet  per  second 
(about  109  miles  an  hour).  In  the  case  of  falling  bodies  the  relation 
between  the  vertical  distance  fallen  through  (h)  and  the  acquired  velocity 
(v)  is  expressed  by  the  formula  v  =  V2  gh,  g  being  the  force  of  gravity, 
usually  taken  at  32-2  (it  is  32-165  at  New  York  City)  ;  or,  approximately 
(since  2  g  =  64-3),  by  the  formula  v  =  8  V^,  or  h  =  -fa  v2.  In  actual  experi- 
ence the  theoretical  result  cannot  be  realized.  On  the  contrary,  the  velocity 
of  a  stream  does  not  increase  uniformly  as  it  descends,  and  when  it  reaches 
the  sea,  whatever  the  elevation  at  first,  its  velocity  is  in  most  cases  nearly 
zero.  This  is  owing  to  the  fact  that  its  energy,  instead  of  being  stored  up, 
is  being  expended  against  the  various  resistances. encountered,  that  is  :  — 

(1)  In   overcoming   friction   between   (a)  the  molecules  of  the  water 
itself;   (b)  the  water  and  the  bed  of  the  stream;   (c)  the  surface  of  the  water 
and  the  atmosphere. 

(2)  In  impact,  or  blows  against  the  rocks  or  earthy  material  of  the  bed 
and  banks  of  the  stream ;  and  in  pushing  sand  or  gravel  along  the  bed. 

(3)  In  transporting  earth,  sand,  or  stones,  held  in  suspension  in  the 
water. 

(4)  In  overcoming  the  friction  between  the  transported  particles  and 
the  bed  of  the  stream,  and  the  friction  between  the  particles  themselves; 
and  also  the  loss  from  eddies  made  by  the  character  or  form  of  the  bed 
or  otherwise. 

By  these  means  the  energy  is  so  far  expended  that  no  accumulation  can 
take  place  except  on  portions  of  a  stream  where  the  pitch  is  uniform  and 
considerable,  and  the  bed  is  hard  and  smooth.  In  a  waterfall,  accumulation 
goes  on  during  the  descent ;  but  the  whole  energy  of  the  stream  is  lost  in 
the  stroke  of  the  water  at  the  bottom  of  the  fall,  where  it  is  converted 
into  heat,  —  a  fall  of  772  feet  producing  heat  enough  to  raise  the  tempera- 
ture of  the  water  1°  F. 

Owing  to  the  rapid  increase  of  velocity  in  the  descending  water  of  a 
waterfall,  the  stream  in  a  high  fall  of  small  volume  becomes  divided  up,  the 


WATER   AS    A   MECHANICAL    AGENT.  175 

parts  running  away  from  one  another  and  finally  separating  into  drops  ;  in 
which  case,  owing  to  the  resistance  of  the  air,  the  velocity,  and  therefore 
the  energy,  is  almost  wholly  dissipated,  and  the  fall  becomes  a  veil  of  mist, 
swayed  by  the  winds. 

3.  Velocity  of  rivers.  —  The  velocity  of  rivers  varies  (1)  with  their  slope  — 
strictly  the  slope  of  the  upper  surface ;  (2)  with  the  volume  of  water;  (3)  with 
the  friction  of  the  bottom  and  sides  —  which  increases  with  the  roughness  of 
its  surface,  and  the  shallowness  of  the  stream  for  a  given  volume ;   (4)  with 
the  degree  of  uniformity  of  the  cross-section  and  uniformity  of  course,  —  for 
abrupt  bends  and  shallo wings  increase   friction.      In  other  words,  among 
rivers  a  large  stream  of  considerable  depth,  having  a  width  not  a  score  of 
times  greater  than  its  depth,  and  a  uniform  cross-section  and  course,  will  be 
least  impeded  by  friction  of  the  sides  and  bottom,  and  will  work  most  effi- 
ciently.    Over  a  bottom  of  ordinary  kind  the  velocity  is  greatest  along  the 
line  of  greatest  depth ;  and  in  any  given  section  the  maximum  plane  of  flow 
is  at  or  near  the  surface,  at  about  one  tenth  of  the  depth  (Humphreys  and 
Abbot),  but  varying  between  zero  and  two  tenths.     The  retardation  at  sur- 
face is  attributed  by  Professor  James  Thomson  to  the  friction  of  the  bottom 
and  sides  ;   the  eddying  masses  of  water  are  thrown  off  by  this  friction, 
which  modify  the   velocity  in   all  parts  of  the  stream,  but  most  at  the 
surface. 

The  mean  velocity  is  about  four  fifths  of  the  greatest  velocity ;  or  better, 
according  to  Humphreys  and  A.bbot,  it  is  almost  uniformly  0-955  of  the 
velocity  at  mid-depth.  The  amount  (in  cubic  feet)  of  water  passing  is  equal 
to  the  product  of  the  mean  velocity  into  the  area  of  the  cross-section.  When 
two  streams  unite  without  increase  of  pitch,  the  velocity  is  increased  because 
the  surface  of  friction  is  less  than  in  the  two  flowing  separately. 

Humphreys  and  Abbot,  in  their  Report  on  the  Mississippi  River  (page  312),  give  the 
following  formula  for  calculating  the  velocity  of  large  rivers.  It  is  applicable  strictly  to  a 
limited  portion  of  a  large  river  without  bends.  It  is  as  follows  :  v=  ( [225r,s|] ^— O0388)2, 
in  which  v  is  the  velocity  sought ;  s,  the  sine  of  the  slope  ;  and  r,  the  mean  radius  =  area 
of  cross-section,  «,  divided  by  p  +  W,  or  the  length  of  the  wetted  perimeter  (p)  plus  the 

width  at  surface.     In  the  general  formula,  the  sine  of  the  slope  =  s  =  —  •     I  =  length  of 

a  limited  portion  of  the  river,  h  =  h,  +  hu  =  difference  of  level  of  the  water-surface  at  the 
two  extremities  of  the  distance  Z,  in  which  h,  =  the  part  of  h  consumed  in  overcoming 
the  resistances  of  the  channel  supposed  to  be  straight  and  of  nearly  uniform  cross-section, 
and  h,,  =  the  part  of  h  consumed  in  overcoming  the  resistances  of  bends  and  important 
irregularities  of  cross-section.  In  the  equation  for  large  rivers,  above  quoted,  h,,  is  thrown 
out  by  the  conditions. 

When  a  river  expands  into  a  lake,  the  velocity  of  flow  is  diminished 
because  of  (1)  the  greater  capacity  of  the  lake  for  a  given  amount  of  length ; 
(2)  the  decrease  in  slope ;  and  (3)  the  increased  surface  for  evaporation. 
There  is  little  movement  in  the  waters  that  lie  below  the  level  of  the  outlet. 

4.  Periodicity  in  working-power.  —  Rivers  are  periodical  workers,  owing 
to  periodicity  in  the  day,  the  seasons,  and  in  the  longer  climatal  cycles. 


176  DYNAMICAL   GEOLOGY. 

The  changes  of  the  day  determine  alternations  in  amount  of  evapora- 
tion, and,  with  greater  effects,  alternations  in  the  supply  from  snow-covered 
heights.  The  night  suspends  part  of  the  supply  by  the  freezing  that  goes 
forward ;  and  the  day  starts  the  flow  again,  the  effects  reaching  the  plains 
below  some  hours  after  the  change  in  the  mountains,  so  that  the  night  is 
often  the  time  of  greatest  flow. 

With  the  alternating  seasons,  the  changes  are  of  great  magnitude.  All 
rivers  have  their  annual  season  of  quiet  flow,  when  work  is  often  wholly 
suspended,  extending  usually  through  most  of  the  months  of  the  year ;  and 
then,  once  or  twice  annually,  their  periods  of  floods,  when  lazy  streams 
become  impetuous  torrents,  and  narrow  streams  mighty  rivers,  sweeping 
over  the  bordering  lands  for  miles,  defying  human  attempts  at  management. 

In  mountain  regions,  and  especially  those  of  dry,  almost  rainless 
climates,  storms,  called  cloud-bursts,  sometimes  pass  hurriedly  and  fill  the 
narrow  valleys  to  a  depth  of  100  feet  or  more  in  a  few  hours,  doing  quick, 
short,  destructive  work  over  small  areas. 

The  flood  season  is  geologically  the  working-time  of  rivers.  After  their 
floods  have  passed,  in  which  all  work  is  of  a  broad  sweeping  style,  rivers 
return  to  quiet  action  along  the  bed,  and  often  are  divided  into  several 
feebly  chiseling  strands  along  the  channel.  Sometimes  only  the  stony 
bottoms  of  portions  of  the  channel  are  left  dry ;  or,  as  in  parts  of  Australia, 
there  remains  merely  a  string  of  small,  distant  muddy  pools,  in  which  only 
Fishes  that  are  doubly  equipped  with  breathing  apparatus,  like  the  Ceratodus, 
could  survive. 

Eivers  that  rise  in  snowy  heights,  like  the  Rhine,  Khone,  and  Danube, 
have  their  channels  kept  well  filled  in  summer,  the  time  of  drought,  because 
that  is  the  melting-time  of  the  snows. 

The  flood  season  has  its  effects  prolonged  in  many  regions  by  the  great 
natural  reservoirs  over  the  land  —  the  lakes  and  marshes.  These  stow  away 
the  surplus  waters  and  let  them  out  gradually.  Many  temporary  lakes  are 
made  by  floods  which  prolong  greatly  the  period  of  high  water  under  a  con- 
dition that  is  convenient  for  mill-uses.  Man  makes  reservoirs  for  the  same 
purpose. 

Forest  regions  also  keep  the  soil  beneath  them  charged  with  moisture, 
and,  like  lakes,  help  to  give  rivers  constancy  of  supply  and  uniformity  of 
flow.  And  evil  often  comes  when  the  forests  are  cut  away ;  for  the  rain 
waters  then  speedily  reach  the  river-channels  and  may  occasion  alternate 
periods  of  wasteful  violence  and  worthless  feebleness.  The  cutting  away  of 
the  forests  in  the  French  Alps  (Dauphine)  has  led  to  uncontrollable  erosion, 
despoiled  fields,  and  impoverishment  of  the  people ;  and,  in  America,  to 
annual  seasons  of  dry  mill-ponds,  an  immense  sacrifice  of  available  water- 
power,  and  the  desertion  of  many  a  mill-site. 

Where  a  river  has  its  rainy  region  confined  to  the  mountains  about  its 
source,  and  flows  below  through  dry  plains,  the  floods  travel  gradually  down 
the  stream,  losing  by  evaporation  and  soil  absorption  as  they  flow  on.  There 
is  often  much  hard  work  done  in  the  mountains,  and  little  below. 


WATER   AS   A   MECHANICAL   AGENT.  177 

The  floods  of  the  Nile  commence  in  southern  Abyssinia  (where  the 
annual  fall  of  rain  is  50  inches  or  more)  in  April,  and  reach  Cairo  in  mid- 
summer, and  exert  their  beneficial  influence  over  all  the  flood  grounds 
by  the  fertile  silt  deposited,  which  is  estimated  to  amount  annually  to 
140  millions  of  tons.  The  maximum  rise  is  40  feet,  and  the  area  of  the 
region  flooded  is  2100  square  miles. 

The  distribution  of  tributaries  influences  the  time  and  amount  of  floods. 
In  the  Amazon,  the  tributaries  north  of  the  equator  are  flooded  during  the 
rainy  season  of  the  northern  hemisphere,  and  those  south,  during  that  of  the 
southern.  In  this  way  many  rivers,  by  their  widespread  arms,  take  advan- 
tage of  the  differences  in  the  seasons  or  climates  of  the  distant  countries 
whence  they  get  their  supplies.  The  floods  of  the  Amazon  convert  the  larger 
part  of  its  500,000  miles  of  silvas  into  one  great  lake  ;  3000  miles  up  the  river, 
an  elevation  above  tide  of  only  210  feet  is  reached.  The  Mississippi  hardly 
feels  the  great  floods  of  the  Ohio  unless  they  come  when  the  Kocky 
Mountain  tributaries  are  also  flooded ;  and  these  western  tributaries  are  so 
widely  distributed  and  so  large  that  they  may  make  successive  floods,  or  pour 
in  all  together  in  one  vast  deluge,  giving  the  Mississippi  in  some  places 
below  the  Ohio  a  breadth  of  50  miles.  At  high  water  the  flood-level  is  70 
feet  above  low  water  at  Cincinnati,  51  on  the  Mississippi  at  Cairo,  and  17  at 
New  Orleans. 

The  cycles  of  rainy  and  dry  seasons  sometimes  seem  to  correspond  with 
the  sun-spot  cycle  of  11  years ;  and  greater  cycles  include  4  or  5  of  the  11- 
year  cycles.  No  definite  conclusions  have  as  yet  been  formed  regarding  this 
point. 

5.  Causes  tending  to  determine  the  direction  of  draining  courses.  —  The 
chief  causes  are  the  following.  As  regards,  — 

(a)  Slope.  —  The  steepest  descent  accessible. 

(b)  Surf  ace- form.  —  A  depression  leading  downward  to  concentrate  the 
waters  from  a  large  area  for  work. 

(c)  Basement  rocks.  —  The  belt  of  least  resistance  to  wear.     In  the  case 
of  upturned  strata,  whether  folded  or  in  monoclines,  the  belt  of  weaker 
rock  in  the  line  of  strike ;  or  over  folded  rocks,  the  course  of  a  region  of 
warped  strata  between  the  extremities,  overlapping  or  not,  of  the  folds  (page 
388). 

(d)  Fractures,  faults.  —  The  courses  of  great  fractures  and  faults,  and 
especially  those  attending  the  flexing  of  rocks  in  mountain-making,  as,  for 
example,  those  which  determined  the  location  of  the  Great  Appalachian 
valley  of  eastern  Tennessee  and  its  continuation  northeastward  (page  356). 

(e)  Meteorological  conditions.  —  The  belt  or  region  of  greatest  precipi- 
tation. 

DENUDATION. 

1.  Work  of  the  rain-drop. — Denudation  by  simple  impact  of  water  com- 
mences with  the  descending  rain-drop.  The  drop  makes  a  shallow  impres- 

D ANA'S   MANUAL — 12 


178 


DYNAMICAL   GEOLOGY. 


158. 


Drop-made  columns.    D.  '87. 


sion  on  soft  earth  or  mud  by  denudation,  which  is  circular  or  elliptical, 
according  as  the  wind  blows  or  not.  These  impressions,  if  they  escape 
obliteration  by  succeeding  drops  and  are  soon  covered  by  a  layer  of  sediment, 
become  "  fossil  rain-marks,"  and  many  surfaces  so  marked  exist  in  the  older 
rocks,  bearing  evidence  as  to  former  rains,  and  also  as  to  the  above-water 
level  of  the  surface  rained  on.  It  may  have  been  a  mud-flat  exposed  between 
high  and  low  tides.  When  the  drops  strike  a  gravel  bed,  stones  in  the  gravel 
will  protect  the  material  directly  beneath,  while  erosion  around  may  cut 
away  the  material,  and  leave  standing  slender  columns,  each  capped  with  a 
stone,  as  monumental  evidence  of  the  work  done. 

A  miniature  specimen  of  this  work  was  observed  by  the  author  in  1887, 
alongside  of  the  path  leading  down  into  Kilauea.  It  had  been  produced  by 
drops  falling  from  shrubbery,  wet  with  the  heavy 
mist  of  the  night,  to  a  bed  of  earth,  three  or  four 
feet  below.  A  portion  of  the  scene  is  represented, 
natural  size,  in  Fig.  158. 

Columns  of  10  to  30  feet  are  often  made  out  of 
beds  of  gravel,  glacial  drift,  and  the  like.  Fig.  159 
represents  a  case  near  Antelope  Park,  on  a  small  trib- 
utary of  the  Kio  Grande,  where  a  bed  of  tufa,  over 
500  feet  thick,  contains  large  stones.  The  waters  of 
the  rains  descending  along  the  surface  of  a  vertical  wall  first  made,  beneath 
the  stones,  bas-reliefs  of  columns,  and  then  the  free  columns  j  and,  in  the 
end,  an  area  three  miles  long  and  half  a  mile  wide 
was  thickly  covered  with  the  columns,  many  60  to  80 
feet  high,  and  some  400  feet  (Endlich,  1875). 

The  power  of  water-strokes  is  well  illustrated  by 
the  effects  in  gold-washings  from  a  jet  under  a  head 
of  pressure  derived  from  the  water  in  an  elevated 
reservoir,  as  in  California  hydraulic  mining.  The 
beds  of  compact  auriferous  gravel  gradually  return  to 
their  original  condition  of  loose  earth  and  stones, 
although  struck  only  by  a  mass  of  pure  water. 

At  Niagara,  the  spray  made  by  the  waterfall, 
carried  forcibly  into  an  open  chamber  behind  the 
fall,  causes  the  wear  of  the  shales  (James  Hall). 

2.  The  excavation  of  valleys  ;  Denudation.  —  Ero- 
sion, excavation  and  denudation,  or  land-sculpture,  are 
parts  of  one  process.  The  simplest  illustrations  of 
the  subject  are  afforded  by  the  great,  gently  sloping, 
volcanic  mountains,  made  up  chiefly  of  stratified 
streams  of  basaltic  lavas.  In  them,  the  slopes  are 

but  5°  to  10°,  and  conditions  determining  direction  of  drainage  are  in  general 
reduced  to  two,  the  first  and  the  last  of  those  mentioned  on  page  177.  The 
facts  here  presented  are  from  the  author's  observations  of  1839-1841,  pub* 
lished  in  his  Exploring  Expedition  Report,  1849. 


159. 


Rain-made  columns  x  "04. 
Endlich,  '75. 


WATER    AS    A    MECHANICAL   AGENT. 


179 


The  earliest  stages  are  well  illustrated  in  the  Hawaiian  mountains.  One 
of  them,  Mount  Loa,  13,675  feet  high  (see  Figs.  227  and  229),  is  still  active ; 
consequently  it  is  without  river  valleys  or  gorges.  Another,  Mount  Kea, 
13,805  feet,  has  many  gorges  on  the  wet  or  windward  side,  extending  upward 
from  the  coast,  where  they  are  several  hundred  feet  deep ;  but  they  go  only 
half-way  to  the  top.  The  leeward  side  is  yet  unchanneled. 

The  map  here  introduced  is  that  of  the  adjoining  island  of  Maui. 

160. 


On  eastern  Maui,  the  cone,  10,000  feet  high,  has  a  somewhat  less  recent 
aspect  in  its  rocks  than  that  of  Mount  Kea.  It  has  channels  on  its  wind- 
ward slopes,  some  of  which  reach  up  to  the  edge  of  its  great  crater ;  but  on 
the  leeward  side  only  narrow  trenches  that  seldom  contain  water.  At  the 
same  time,  western  Maui,  nearly  6000  feet,  has  profound  valleys  in  place  of 
the  many  small  ones,  marks  of  very  long  exposure  to  denuding  agents ;  and 
another  island  of  the  group  farther  west,  Oahu  (Fig.  257),  is  like  Maui  in 
having  a  western  volcano  in  ruins,  —  a  few  crests  and  profound  valleys  in 
place  of  even  slopes,  and  an  eastern  volcano  of  much  more  recent  aspect, 
though  more  gorged  than  eastern  Maui.  But  it  met  with  a  disaster  in  which 
over  half  of  its  mass  sunk  beneath  the  ocean,  leaving  a  precipice  for  20  miles 
facing  the  northwest  or  to  windward.  The  nearly  vertical  surface  has  con- 
sequently a  range  of  alcoves,  finely  illustrating  this  style  of  mountain  archi- 
tecture. To  the  northward  the  alcoves  are  lengthened  into  gorges.  Moreover, 
over  eastern  Oahu  the  winds  pass  the  summit  of  the  precipice  before  the  cold 
heights  have  deprived  them  of  their  moisture,  so  that  the  leeward  slopes  take- 


180 


DYNAMICAL   GEOLOGY. 


it,  and  show  the  fact  of  this  reenforcement  of  the  streams  in  the  depth  of 
the  valleys. 

Finally,  in  Tahiti,  as  is  shown  in  the  map  below,  the  work  of  erosion  is  in 
a,  sense  completed,  in  spite  of  the  general  covering  of  vegetation.  The  few 
great  valleys,  which  here  take  the  place  of  the  many  of  the  early  stages  of 
erosion,  extend  to  the  coast ;  and  these  valleys,  instead  of  narrowing  to  the 

181. 


Map  of  Tahiti,  the  coral  reefs  excluded;  the  lower  side  is  the  northern,  or  that  toward  the  equator: 
PP,  village  of  Papenoo;  M,  of  Matavai;  P,  of  Papaua;  T,  of  Toanoa;  P',  of  Papieti,  the  largest;  P",  of 
Punaavia.  The  valleys  are  named  from  the  villages  on  the  coast  at  their  termination.  Wilkes'  Exploring 
Expedition  Report. 

summit,  widen  ont  and  stop  off  abruptly  under  precipices  of  at  least  3000 
feet.  Some  widen  at  their  head  into  great  amphitheaters  or  circs  (the 
"cirques"  of  French  authors),  illustrating  well  the  origin  of  such  amphi- 
theaters. 

In  the  above  examples,  the  rains  and  mists  of  the  higher  and  cooler 


WATER    AS    A   MECHANICAL   AGENT. 


181 


parts  of  the  mountains,  and  especially  those  of  the  windward  side,  are  the 
source  of  the  water.  The  slopes  collect  it  as  it  descends  into  streamlets; 
these  increase  toward  the  foot,  where  the  valley,  as  Mount  Kea  shows,  first 
takes  shape. 

The  diagram  Fig.  162,  although  greatly  exaggerated  in  angle  of  slope,  — 
that  of  the  line  AB,  —  will  serve  to  illustrate  the  steps  of  progress.  In  the 
early  stage  a  valley  forms  toward  the  base  of  the  mountain,  having  its  bed 


162. 


163. 


along  Im ;  and  later  along  no.  On  reaching  o,  the  most  of  the  descent  of 
the  declivity  is  made :  the  waters  from  o  to  B  have,  therefore,  little  eroding 
power  at  bottom,  and  commence  to  erode  laterally  during  freshets,  under- 
mining the  cliffs  on  either  side,  when  the  rocks  admit  of  it,  thus  widening 
the  valley  and  making  a  "  flood-plain,"  or  "  bottom-lands,"  by  deposition  of 
the  transported  material  in  consequence  of  the  slackened  flow.  The  river, 
in  this  state,  consists  of  its  torrent-portion,  Ano,  and  its  river-portion,  oniB. 
Along  the  former,  a  transverse  section  of  the  valley  is  approximately  V- 
shaped,  and  along  the  latter  nearly  U-shaped,  or  else  like  a  V  flattened  at 
bottom.  The  river-portion,  oraB,  usually  exhibits,  even  in  its  incipient 
stages,  its  two  prominent  elements,  —  a  river-channel,  occupied  at  low  water, 
andkthe  alluvial  flat,  or  flood-ground,  which  is  mostly  or  wholly  covered  dur- 
ing freshets. 

As  the  waters  continue  their  work  of  erosion  about  the  summits,  where 
the  mists  and  rains  are  generally  most  abundant  and  often  almost  perpetual 
through  the  year,  the  next  step  is  the  eroding  about  the  summit  and  the  con- 
tinued deepening  of  the  torrent-channel,  making  thus  a  precipice  under  the 
summit,  or  toward  the  top  of  the  declivity ;  in  this  stage,  the  course  of  the 
waters  is  ApqB,  and  later,  ArsB.  The  stream  has  now  (1)  a  cascade- 
portion,  and  (2)  a  torrent-portion,  besides  (3)  its  river-portion.  The  preci- 
pices of  the  cascade-portion  may  be  thousands  of  feet  in  height;  and  the 
waters  may  descend  in  many  thready  lines,  to  unite  below  in  the  torrent. 
The  mountain  cone,  in  such  a  case,  may  have  its  top  chiseled  into  a  narrow, 
crest-like  ridge  or  peak,  with  many  vertical  alcoves  in  the  face  of  the  preci- 
pice that  were  made  by  the  falling  and  leaping  streamlets. 

The  next  step  in  the  progressing  erosion,  as  Tahiti  illustrates,  is  the  thin- 
ning and  wearing  away  of  the  ridges  that  intervene  between  adjoining  valleys, 
in  the  higher  regions  where  the  descending  waters  are  most  abundant.  It  is 
in  this  way  that  two  valleys  (or  perhaps  more  than  two,  by  the  wear  of  more 


182  DYNAMICAL   GEOLOGY. 

ridges)  are  combined  into  an  amphitheater  or  circ.  In  Fig.  163,  ArsB  repre- 
sents the  course  of  the  stream,  as  in  Fig.  162;  and  Ae/B  the  eroded  ridge, 
which  has  lost  at  e  much  of  its  height. 

The  ascent  of  the  mountain  by  following  the  valleys  is  in  such  a  case 
wholly  impossible  ;  it  can  be  accomplished  only  by  finding  the  ridge  that  has 
held  on  to  its  summit  connection  with  the  peak.  On  Tahiti  the  ridge  by 
which  the  author  made  his  ascent  to  b,  the  peak  called  Aorai,  about  6000  feet 
in  height,  narrowed  to  two  or  three  feet,  and  for  a  short  distance  to  a  single 
foot,  putting  risks  into  the  excursion,  since  the  slope  either  side  fell  off  for 
1000  to  2000  feet  at  an  angle  of  60°  to  70°.  Between  b  and  a  (the  highest 
peak,  Orohena)  the  "  divide  "  was  reduced  in  height  more  than  1000  feet,  and 
the  summit  at  b  was  but  six  feet  broad.  All  the  outlines  of  the  original 
crater  had  disappeared.  The  lavas  usually  lie  in  beds  dipping  seaward,  but 
those  of  the  central  precipices  were  without  bedding. 

From  the  steps  in  the  work  of  erosion  over  such  isolated  volcanic  moun- 
tains it  becomes  evident  that  further  progress  would  result  in  narrower, 
thinner,  and  if  possible  steeper  ridges ;  and,  even  when  nearing  the  end,  in 
sharp  crests  and  ridges,  which  finally  would  be  likely  to  disappear  through 
weathering  agencies.  A  flattening  of  the  mountain  would  come  at  the  very 
end,  and  not  be  a  step  in  the  progress  toward  it. 

These  explanations  show  that  a  river  rising  in  high  mountains  has  (1)  its 
torrent-portion,  and  (2)  its  river-portion,  along  which  it  is  bordered  by  flood- 
grounds. 

The  river-portion  consists  (1)  of  an  upper  section  of  rapid  waters,  along 
which  erosion  at  bottom  is  continued,  and  the  amount  removed  exceeds  that 
of  deposition ;  (2)  a  section  of  feebler  descent  and  slower  flow,  where  the 
removal  by  erosion  in  floods  does  not  exceed  that  of  subsequent  deposition, 
so  that  the  stream  has  ceased  efficient  work.  It  has  reached  base-level  —  as 
the  condition  has  been  termed  by  J.  W.  Powell.  This  base-level  section 
may  end  below  in  a  decrepit  portion,  over  which  deposition  along  the  bed 
exceeds  the  amount  removed  in  floods,  so  that  thus  a  silting  up  of  the  chan- 
nel, and  also  a  corresponding  rise  of  the  flood-grounds,  go  on. 

In  the  small  Pacific  islands  these  sections  of  the  river-portion  of  a  stream 
are  short  and  not  alwaj^s  present.  But  on  the  western  side  of  Maui  there  are 
remarkable  examples  of  a  decrepit  ending ;  for,  while  the  valleys  in  the  wet 
and  cool  mountains  are  wide  and  profound,  as  the  map  shows,  the  stream  over 
the  leeward  (and  hence  nearly  rainless)  plain  at  the  western  foot  is  reduced 
to  a  narrow  trench,  which  part  of  the  time  is  dry. 

3.  River  valleys  of  the  continents.  —  Over  a  continent  where  declivities  are 
long,  and  the  gently  sloping  plains  have  large  extent,  —  often  hundreds  of 
miles  in  width,  —  each  of  the  divisions  of  the  river-portion  of  a  stream,  that  of 
rapid-working  waters  and  that  of  base-level,  is  often  of  great  length.  More- 
over, along  many  streams  there  are  often  several  base-level  portions,  made  by 
obstructions ;  but  where  this  is  the  case,  as  Powell  remarks,  it  is  evidence  of 
the  relatively  recent  origin  of  the  stream;  for  the  wear  of  ages  tends  to 


WATER   AS    A   MECHANICAL   AGENT.  183 

remove  the  obstructions  and  reduce  the  stream  throughout,  or  far  toward  its 
source,  to  a  base-level  condition. 

In  New  South  Wales,  Australia,  where  a  friable  Triassic  sandstone  2000  to 
4000  feet  thick  is  the  prevailing  rock  over  large  regions,  the  river-portion  of 
some  streams  is  continued  from  the  coast,  between  nearly  vertical  walls  of 
the  sandstone,  almost  to  the  mountains,  and  there  ends  abruptly  in  the  cas- 
cade portion  of  the  source.  The  following  figure  illustrates  the  steps  of 
progress :  first,  the  cut  of  a  torrent-channel  to  Cnl ;  and  then  the  retreat  of 
the  torrent  portion  by  the  continued  wear,  and  the  lengthening  of  a  river- 
portion  from  nl  to  n2  and  so  on  to  w4,  n5,  n6,  when  the  torrent-portion  is 
reduced  to  a  series  of  waterfalls.  Over  the  wetter  interior  portion  of  the 

164. 


Ideal  section  illustrating  progressing  erosion  of  a  stream.    D.  '49. 

country  the  valleys  have  often  great  breadth,  and  at  the  head  widen  into 
circs,  owing  to  the  many  streams  descending  the  steep  sides ;  but  toward  the 
coast,  where  the  climate  is  relatively  dry,  the  breadth  does  not  much  exceed 
that  of  the  inclosed  stream. 

A  model  of  a  system  of  erosion  is  often  admirably  worked  out  in  the 
earthy  slopes  along  a  roadside,  —  the  little  rill  having  its  cascade-head,  then 
its  torrent-channel,  and,  below,  its  flat  alluvial  plain,  intersected  by  the  little 
winding  water-channel;  some  of  the  ridgelets  worn  away  in  their  upper 
parts,  until  two  or  more  little  valleys  coalesce ;  then,  at  times,  the  head  of 
the  coalesced  valleys  widened  into  an  amphitheater,  and  the  walls  fluted  into 
a  series  of  alcoves  and  buttresses. 

The  process  of  raising  the  bed  and  flood-grounds  of  a  river  is  often  pro- 
moted by  the  embankments  made  along  the  lower  part  of  their  course  to 
prevent  extensive  flooding,  and  to  increase  the  depth  by  scouring.  On  some 
Japan  rivers,  the  beds,  owing  to  the  silting  and  the  consequent  making  of 
artificial  embankments,  are  now  40  feet  above  the  plains  over  which  they 
flow.  In  all  improvements,  it  has  to  be  remembered  that  the  amount  of 
water  discharged  by  a  flooded  Mississippi  cannot  be  lessened  by  choking  it. 
It  must  and  will  have  room  to  flow  in,  however  desirable  it  may  be  to  rob  it 
for  storehouses  and  dwellings. 

The  flood-grounds  of  some  large  rivers  extend  scores  of  miles  from  tlie 
low-water  channel.  On  the  Mississippi,  abreast  of  Tennessee,  they  are  in 
some  parts  over  50  miles  wide ;  on  the  Amazon  (up  which  the  tides  go  400 
miles),  over  100  miles;  and  on  the  Paraguay  there  are  lagoons  300  miles 
in  length. 

4.  Bends.  —  Where  the  pitch  of  the  stream  is  very  small,  any  obstruction, 
or  inequality  of  bottom,  that  throws  the  flow  of  maximum  velocity  to  one  side 


184  DYNAMICAL   GEOLOGY. 

of  the  axial  line,  causes  it  to  strike  and  erode  the  bank  in  front  and  deepen 
the  water,  and  to  transfer  the  sand  or  earth  removed  by  the  erosion  to  the 
opposite  bank  of  the  stream  for  a  sand-flat ;  and  it  thus  commences  a  curve 
in  its  course,  which  may  become  a  deep  bend ;  and  this  bend  may  continue 
the  action  and  be  the  occasion  of  a  succession  of  such  windings.  The  length 
of  the  Mississippi  between  the  mouth  of  the  Ohio  and  the  head  of  the  passes 
at  the  Gulf  of  Mexico  is  1080  miles,  while  the  actual  distance  in  a  straight 
line  is  about  500  miles.  Cutting  off  a  bend  to  shorten  the  distance  along 
the  stream  increases  at  the  place  the  pitch,  and  thereby  the  velocity,  and 
gives  the  waters  greater  eroding  power.  The  flow,  consequently,  would 
deepen  the  channel.  But  it  is  likely  also  to  erode  the  banks,  and  may  carry 
away  all  the  farming  land  the  cut  was  intended  to  gain  or  make  accessible. 
During  great  floods,  a  stream  may  cut  oft'  one  or  more  of  its  bends,  as  has 
happened  in  the  Mississippi,  along  which  narrow  loop-form  lakes  and  dry 
channels  have  thus  been  made. 

Many  examples  are  on  record  of  gorges,  hundreds  of  feet  deep,  cut  out  of 
the  solid  rock  by  only  two  or  three  centuries  of  work.  Lyell  mentions  the 
case  of  the  Simeto,  in  Sicily,  which  had  been  dammed  up  by  an  eruption  of 
lavas  in  1603.  In  two  and  a  half  centuries,  it  had  excavated  a  channel  50 
to  several  hundred  feet  deep,  and  in  some  parts  40  to  50  feet  wide,  although 
the  rock  is  a  hard  solid  basalt.  He  also  describes  a  gorge  made  in  a  deep 
bed  of  decomposed  rock,  three  and  a  half  miles  west  of  Milledgeville,  Ga., 
that  was  at  first  a  mud-crack  a  yard  deep  in  which  the  rains  found  a  chance 
to  make  a  rill,  but  which  in  20  years  was  300  yards  long,  20  to  180  feet  wide, 
and  55  feet  deep ;  and  Liais  describes  a  similar  gorge,  of  twice  the  length,  in 
Brazil,  made  in  40  years. 

5.  Eddies,  Pot-holes,  Kettle-holes.  —  Flowing  water  gathers  into  its  current 
any  still  waters  alongside,  to  fill  the  void  behind,  which  the  flow  tends  to  pro- 
duce, and  thus  eddies  and  eddy  currents  are  made.  When  alongside  of  a  rapid 
current,  any  obstruction  or  shallowing  causes  there  a  diminished  velocity; 
eddies  become  whirls,  and  the  whirling  waters  bear  around  stones  which 
abrade  the  rock  beneath  —  new  stones  being  carried  in  to  replace  old  ones  as 
they  wear  out.  This  kind  of  boring  often  goes  on  with  hardly  more  change 
of  center  than  in  a  carpenter's  work  with  his  augur,  and  deep  cylindrical  holes 
have  been  bored  into  the  hardest  rocks.  Under  a  waterfall  a  broad  basin 
may  be  excavated  in  like  manner.  Pot-holes  are  usually  from  1  to  6  feet  in 
diameter,  and  2  to  20  feet  deep. 

Kettle-holes  are  nearly  circular  basin-like  holes  50  to  150  feet  and  more 
in  diameter,  in  stratified  or  unstratified  sands,  gravel,  or  drift.  For  some 
reason  they  have  failed  to  become  filled  up  to  the  level  of  the  region  around. 
With  regard  to  some,  at  least,  of  those  in  stratified  terrace  formations  (see 
page  299),  the  facts  appear  to  indicate  that  the  spots  were  originally  holes 
of  moderate  size  and  depth  in  the  surface  beneath ;  and  that  in  the  rush  over 
the  spots  by  the  flood  waters  that  deposited  the  stratified  material,  the 
waters  kept  them  free  of  detritus  by  the  whirl  occasioned  by  the  depth. 


WATER   AS   A   MECHANICAL   AGENT.  185 

6.  Waterfalls.  —  The  facts  reviewed  show  that  waterfalls  are  often  a  conse- 
quence of  the  alternation  of  hard  and  soft  strata  in  the  course  of  flowing 
waters.     The    hard   strata  resist   downward   wear;    the  soft  yield   easily. 
Down  the  waters  go,  working  with  new  force  from  the  fall ;  hence  they  un- 
dermine the  hard  bed  and  thereby  steepen  the  descent  often  to  a  vertical  or 
even  an  overhanging  front.     The  columns  made  by  drops  (page  178)  partly 
illustrate  the  principle. 

The  waterfalls  about  the  head  waters  of  rivers  in  the  mountains  have  a 
different  origin ;  for  the  lofty  precipices  may  be  cut  out  of  a  single  block  of 
rock,  as  in  the  case  of  the  central  portion  of  Tahiti.  These  precipitous  walls 
are  a  consequence  of  the  prolonged  erosion  of  a  region  until  a  larger  part  of 
the  vertical  descent  of  the  stream  is  made  at  or  near  its  head. 

Waterfalls  far  down  the  courses  of  rivers,  like  that  of  Niagara,  are  looked 
upon  as  evidence  of  the  recency  of  that  part  of  the  channel  which  contains 
the  fall  (Powell).  But  those  about  the  source  in  the  mountains  may  be, 
on  the  contrary,  a  final  result  after  a  long  era  of  erosion ;  not  the  ultimate 
result,  for  the  last  end  of  the  work  would  be  the  degradation  and  removal 
of  the  crested  heights. 

7.  Features  of  mountains  ;  Forms  made  by  water-sculpture.  —  Elevations  of 
all  kinds  have  derived  their  existing  features  largely  through  water-sculp- 
ture.     Tahiti  was  originally  a  lofty  mountain,  probably  twice  its  present 
height,  with  low,  nearly  even,  downward  slopes  in  all  directions,  and  only 
small  unevennesses  from  the  piling  here  and  there  of  lavas  through  localized 
eruptions.     It  now  is  a  mountain  of  peaks,  crested  ridges  with  lofty  preci- 
pices, and  vertical  lines  in  all  the  features.     But  water  has  no  need  of  a 
mountain  mass  to  make  the  grandest  of  so-called  mountains.     It  will  work 
an  elevated  plateau,  horizontal  in  surface,  into  mountain  forms,  and  so  make 
mountains  without  any  upturning  or  uplifting  except  that  of  the  plateau. 

The  chief  part  of  the  features  produced  come  from  the  alternation  of 
hard  and  soft  strata  among  the  stratified  rocks ;  and  these  are  greatly  varied 
by  the  positions  of  the  strata.  The  elements  of  this  system  of  architecture 
are  well  illustrated  in  the  figures  on  page  186  by  Lesley,  taken  from  his 
work  on  Coal  and  its  Topography  (1856),  in  which  the  author  has  given 
the  results  of  extensive  personal  observation  in  the  Appalachian  region.  The 
harder  strata  may  be  hard  sandstone  or  limestone,  and  the  softer,  shale  or 
crumbling  sandstone.  The  first  figure  (165)  illustrates  the  origin  of  a 
"table  mountain"  or  "mesa"  (Spanish  for  table),  a  hard  layer  making  the 
top,  and,  by  resisting  wear,  protecting  the  softer  beds  directly  below  it.  The 
other  figures  illustrate  other  effects,  under  the  same  principle,  in  rocks  having 
various  positions.  Figs.  166  to  172  are  synclines,  and  173  to  176,  anticlines, 
of  different  forms,  in  three  of  which  a  valley  has  the  place  of  the  upward 
bend  —  a  common  fact  in  the  Appalachian  Mountains. 

Monument  Park  in  Colorado  is  a  region  of  Tertiary  sandstone  carved  into 
monumental  forms  by  denuding  processes,  the  winds  having  given  finishing 
touches.  As  the  view  shows,  the  thin,  harder  layers  in  the  sandstone  make 
the  caps  and  moldings  of  the  monuments. 


186 


165. 


DYNAMICAL   GEOLOGY. 
166. 


167. 


168. 


169. 


170. 


171. 


172. 


173. 


174. 


175. 


176. 


177. 


Sections  illustrating  results  of  denudation.    Lesley. 

The  Colorado  Canon,  along  an  east  and  west  portion  of  the  river,  between 
the  meridians  of  111°  and  115°  W.,  3000  to  more  than  5000  feet  in  depth, 
affords  grand  illustrations  of  canon-making  by  water-sculpture.  It  was 

studied  at  some  point,  by  Newberry  in 
the  Ives  expedition  in  1857-58,  and  more 
fully  by  Powell  in  1869-1872.  The  rocks 
are  horizontal  or  nearly  so,  and  their 
edges  make  the  vertical  walls  of  the 
canon.  In  some  parts  the  canon  is  cut 
out  clean  from  side  to  side,  with  barely 
room  between  precipitous  walls  3000 
feet  high  for  the  stream,  as  in  the  "  Mar- 
ble Canon,"  (Fig.  178)  —  an  eastern  por- 
tion of  the  stream  north  of  the  west- 
ward bend.  In  other  parts,  a  wide  region 
intervening  between  the  lofty  walls  of 
rock  is  sculptured  throughout  into  moun- 
tains 3000  to  5500  feet  in  height,  consti- 
tuting a  group  of  architectural  structures 
of  unsurpassed  grandeur.  Part  of  one  of 
the  views  from  Captain  C.  E.  Button's 
History  of  the  Grand  Canon  (1882)  is  given  on  page  188.  The  principal 
mass  to  the  left  of  the  center  bears  the  name  of  Vishnu's  Temple,  and 
has  a  height  above  its  base  of  5500  feet.  The  walls  in  the  distance  are 
the  northern  walls  of  the  canon,  and  the  foreground  to  the  right  in  front  is  a 
portion  of  the  opposite  or  south  side.  The  deeper  part  of  the  canon,  at  the 
base  of  this  side,  containing  the  river  channel,  is  not  in  the  view.  The 
peaks  of  the  interior  are  higher  than  the  Appalachians.  As  all  is  bare  rock, 
the  view  is  a  remarkably  instructive  example  of  simple  denudation. 


Erosion,  Monument  Park,  Colorado.    Hayden. 


WATER   AS  A  MECHANICAL  AGENT. 


187 


The  effects  of  alternation  in  hard  and  soft  layers,  distantly  spaced  or 
grouped,  appear  throughout  the  scene.  Besides,  there  are  columnar  lines 
due  to  vertical  joints  in  the  harder  beds,  or  to  rill-work  down  the  vertical 
and  sloping  surfaces. 


178. 


Marble  Canon.    From  a  photograph. 


The  rock  of  the  level  region  either  side  of  the  canon,  and  of  the  upper 
part  of  the  walls,  is  Carboniferous  limestone.  Below  are  Paleozoic  sand- 
stones and  other  limestones,  descending  to  the  Cambrian ;  at  bottom,  in 
some  parts,  and  for  a  height  of  500  to  1000  feet  above,  the  rocks  are  granitic. 

Many  views  of  the  Colorado  Canon  also  show  ranges  of  flat-topped 
mountain  heights  to  the  north,  all  of  which  have  similar  architectural 
features  in  their  declivities,  yet  with  peculiarities  belonging  severally  to 
the  rocks  of  the  different  periods  represented.  As  described  by  Dutton, 
first,  in  the  ascent  to  the  summit,  there  are  the  Triassic  "Vermilion  Cliffs"; 
above  these  the  white  and  red  Jurassic ;  then  the  pale  yellow,  gray,  and 
brown  Cretaceous  strata ;  and  at  the  top  great  plains,  the  High  Plateaus  of 
Utah,  the  highest  nearly  12,000  feet  above  sea  level,  which,  unlike  the 
slopes,  are  covered  in  some  parts  with  forests.  The  vegetation  at  the  sum- 
mit is  accounted  for,  says  Dutton,  by  the  fact  that  the  rainfall  there  is  30 
inches  a  year,  while  only  four  to  eight  inches  in  the  lower  country.  These 
mountain  plateaus  are  remnants  of  formations  that  once  covered  the  canon 
region  and  extended  far  away  into  Arizona. 


188 


DYNAMICAL   GEOLOGY. 


The  results  are  the  more  marvelous  in  that  they  are  the  work  of  the  later 
part  of  geological  time,  commencing  after  the  Tertiary  era  had  begun.  They 
show  that  to  produce  a  mountain  group,  with  summits  thousands  of  feet  above 
the  plain  around,  it  is  only  necessary  that  subterranean  action  should  make 
a  plateau  of  sufficient  extent  and  elevation.  Through  the  rains,  the  sculp- 
turing will  all  be  done  in  time.  Many  of  the  so-called  mountains  of  Colo- 

179. 


View  of  peaks  and  ridges  within  the  Colorado  Cafion,  south  of  the  Kaibah  Plateau.    W.  H.  Holmes. 

rado  and  other  parts  of  the  Kocky  Mountain  region,  and  some  of  those  in 
eastern  America,  as  the  Catskills  in  New  York,  and  parts  of  the  Alleghanies, 
consist  of  nearly  horizontal  strata,  and  are  examples  —  not  of  mountains  made 
by  upturning,  but  of  plateaus  carved  into  models  of  mountains.  Scotch  val- 
leys and  elevations  so  modeled  gave  Hutton  the  first  right  ideas  on  this  subject. 
The  "  harder "  rocks  in  the  scenes  described,  it  is  to  be  understood,  are 
not  granite,  gneiss,  syenyte,  and  the  like  ;  they  are  not  rocks  of  any  particular 
kind.  Granite  may  constitute  the  loftiest  and  boldest  of  ridges  and  moun- 


WATER   AS   A   MECHANICAL  AGENT.  189 

tain  needles ;  but  much  of  the  granite  of  the  world  easily  crumbles  under 
atmospheric  influences,  and  makes  the  tamest  of  scenery.  Slates  standing 
on  end  often  bristle  slopes  with  projecting  ledges,  and  rise  into  lofty  needles 
that  defy  the  elements,  like  the  Matterhorn  in  the  Alps ;  but  other  slates  are 
fragile,  and  wear  down  into  hills  of  gentle  earth-covered  slopes. 

8.  Climatal  effects.  —  Climatal  causes  also  have  great  effect  on  the  work 
of  rivers.  A  wet  climate  produces  abundant  vegetation,  which  is  more  or 
less  a  protection  from  wear ;  and  in  tropical  regions  it  covers  even  precipices 
with  ferns  and  other  foliage.  It  also  occasions  rapid  decay  by  the  chemical 
and  other  weathering  methods.  Moreover,  it  sometimes  makes  deep,  hard- 
working rivers,  torrents  that  sweep  away  roughly,  degrade  rapidly  and  per- 
sistently and  leave  behind  massive  peaks,  broad  mountains,  earth-covered 
slopes  ribbed  or  belted  by  the  more  enduring  beds,  with  gently  swelling  out- 
lines over  the  lower  slopes,  and  foliage  almost  everywhere. 

A  dry  climate,  on  the  contrary,  as  in  the  Colorado  region,  and  that  of 
Yellowstone  Park,  makes  small  streams  or  streamlets  in  the  mountain  valleys, 
many  of  which  through  much  of  the  year  are  only  threads  of  water,  if  not 
wholly  dried  up.  They  hence  finish  off  with  sharp  and  delicate  outlines. 
All  the  variations  of  the  beds  in  hardness  are  expressed  in  series  of  pro- 
jecting edges  beneath  the  broader  shelves  and  entablatures.  The  jointed 
structure  of  the  thick,  durable  beds  adds  much  to  the  diversity  of  surface, 
instead  of  insuring  the  removal  of  the  beds.  The  winds  also  aid  with 
lighter  finger. 

In  such  regions,  color  from  foliage  may  fail.  But  the  dripping  waters  of 
the  occasional  rains,  or  the  oozings  through  the  steep  mountain-sides,  transfer 
to  the  surface  the  results  of  oxidations  and  deoxidations,  and  paint  the  walls 
with  various  delicate  tints. 

Even  alternations  of  half-hardened  clay-beds  and  sand-beds,  under  such 
conditions,  as  Colorado  scenery  illustrates,  may  be  cut  into  groups  of  pinnacles, 
turrets,  and  columns  finished  with  capitals  and  bases  which  will  last  indefi- 
nitely ;  for  whatever  the  occasional  supply  of  waters  to  the  channels,  it  ends 
in  reproducing  the  same  features  in  the  soft  beds.  Appalachian  rains,  as 
Powell  says  in  his  work  on  the  Colorado  Canon  (1875),  would  soon  oblit- 
erate much  of  Colorado  scenery.  The  excavation  of  the  Colorado  Canon 
has  been  chiefly  due  to  great  floods;  but  the  finishing  work  carried  on 
within  it  has  been  of  the  gentler  kind. 


TRANSPORTATION  AND  DEPOSITION. 

Amount  of  material  transported  and  deposited  by  rivers.  —  The  materials 
transported  by  running  waters  are  (1)  stones,  pebbles,  sand,  and  clay  or 
earth ;  (2)  logs  and  leaves  from  the  forests,  and  sometimes  trees  that  have 
been  torn  up  or  dislodged  by  the  current ;  (3)  Mollusks  and  their  dead  shells, 
Worms,  Insects,  etc.,  attached  to  the  logs  or  leaves ;  (4)  occasionally  larger 


190  DYNAMICAL   GEOLOGY. 

animals,  that  have  been  surprised  and  drowned  by  freshets,  or  bones  that 
have  been  exhumed  by  the  waters. 

The  amount  of  transportation  going  on  over  a  continent,  especially  in 
seasons  of  floods,  is  beyond  calculation.  Streams  are  everywhere  at  work, 
rivers  with  their  large  tributaries,  and  their  thousands  of  little  ones  spreading 
among  all  the  hills  and  to  the  summit  of  every  mountain;  and  thus  the 
whole  surface  of  a  continent  is  on  the  move  toward  the  oceans.  The  amount 
transported  is  a  measure  of  the  amount  lost  by  the  land,  as  well  as  of  that 
gained  by  the  river  plains,  lakes,  and  seas.  The  amount  of  silt  carried  to 
the  Mexican  Gulf  by  the  Mississippi,  according  to  the  Delta  Survey  under 
Humphreys  and  Abbot,  is  about  y^Vo"  the  weight  of  the  water,  or  -^-^  its 
bulk;  equivalent  for  an  average  year  to  812,500,000,000,000  pounds,  or  a 
mass  one  square  mile  in  area  and  241  feet  deep. 

The  following  table  contains  the  ratio  of  sediment  to  water  by  weight,  as  obtained  by 
the  Delta  Survey,  and  also  the  results  of  other  investigations. 

Mississippi  River,  at  Carrollton,  by  Delta  Survey, 
Mississippi  River,  at  Carrollton,  by  Delta  Survey, 
Mississippi  River,  at  Columbus,  by  Delta  Survey, 
Mississippi  River,  at  Mouths,  by  Mr.  Meade, 
Mississippi  River,  at  Mouths,  by  Mr.  Sidell, 
Mississippi  River,  at  various  places,  by  Prof.  Riddell, 
Mississippi  River,  at  New  Orleans,  by  Prof.  Riddell, 
Rhone,  at  Lyons,  by  Mr.  Surell, 
Rhone,  at  Aries,  by  Messrs.  Gorsse  and  Subours, 
Rhone,  in  Delta,  by  Mr.  Surell, 
Ganges, 

For  the  Danube,  the  ratio  at  low  water  is  1 :  33,000  ;  at  flood,  1 :  2400 ;  for  the  Po,  at 
flood,  1 :  300  (Lombardini)  ;  for  the  Meuse,  at  low  water,  1  :  71,420  ;  at  flood,  1 :  2100 
(Chandellon)  ;  for  the  Irrawaddy,  at  low  water,  1 :  5725  ;  at  flood,  1 :  1700  (Login)  ;  for 
the  La  Plata  at  Buenos  Ayres,  1 :  7752,  at  which  rate  it  carries  seaward  about  224,000  tons 
of  sediment  each  24  hours,  but  dropping  part  of  it  along  the  100  miles  before  it  reaches 
the  sea  (Higgin). 

The  annual  discharge  of  sediment  from  the  Ganges  has  been  estimated  at  6,369,000,000 
cubic  feet,  or  378,100,000  tons.  The  Nile  brings  down  annually  nearly  150,000,000  tons. 
The  bulk  may  be  calculated,  by  taking  1-9  as  the  specific  gravity  of  the  material. 

Besides  the  material  held  in  suspension,  the  Mississippi  pushes  along  into 
the  Gulf  large  quantities  of  earthy  matter ;  and  the  annual  amount  thus 
contributed  to  the  Gulf  is  estimated  to  be  about  750,000,000  cubic  feet,  — 
which  would  cover  a  square  mile  27  feet  deep ;  and  this,  added  to  the  241 
feet  above  mentioned,  makes  the  total  268  feet. 

This  amount  is  equivalent  to  an  average  of  ^Vff  °^  a  ^°°^  ammally  from 
the  whole  drainage  area  of  the  river ;  or,  in  other  words,  the  area  would  be 
lowered  by  it,  on  an  average,  one  foot  in  4920  years.  The  Ganges  works 
faster,  the  amount  it  transports  to  the  sea  being  such  as  would  lower  its 
drainage  area,  on  an  average,  a  foot  in  1880  years.  All  the  rivers  that  enter 
the  ocean  or  the  seas  over  the  land,  are  working  in  the  same  way,  and  with 
results  to  the  continental  surface  mostly  between  these  two  extremes. 


itio. 
1808 
1449 
1321 
1256 
1724 
1245 
1155 
17000 
2000 
2500. 
858, 

Time. 

12  mos.,  1851-1852. 
12mos.,  1852-1853. 
9  mos.,  1858. 
2  mos.,  1838. 
1838. 
14  days,  summer  of  1843. 
35  days,  summer  of  1846. 
1844. 
4  mos.,  1808-1809. 

at  flood-time. 

WATER   AS   A   MECHANICAL  AGENT.  191 

T.  Mellard  Keade  estimates  that  the  water  (about  68,451,000,000  tons)  which  annually 
runs  off  from  the  area  of  England  and  Wales  carries  to  the  sea  8,370,630  tons  of 
solids  in  solution,  or  1223  parts  in  every  10,000  of  water,  consisting  of  about  0-95  of 
calcium  and  magnesium  carbonates  and  sulphates,  0-166  of  sodium  chloride,  and  the  rest 
nitrates,  sodium  carbonate,  alkaline  sulphates,  silica,  and  iron  sesquioxide ;  and  at  15  cubic 
feet  to  the  ton,  the  denudations  thus  occasioned  would  equal  one  foot  in  12,978  years. 
Prestwich  obtained  (1872),  in  a  similar  calculation,  one  foot  in  12,000  years  for  the  calcium 
carbonate  carried  off  by  the  Thames  from  the  chalk,  greensand,  and  oolitic  formations. 
The  total  annual  denudation  for  England,  from  this  source  alone,  is  made  143-5  tons  per 
square  mile.  The  Rhine,  according  to  Reade's  calculations,  removes  about  92-3  tons  in 
solution  per  square  mile  ;  the  Rhone,  232  tons  ;  the  Danube,  72-7  tons ;  the  Garonne,  142 
tons  ;  the  Seine,  97  tons.  From  these  data  the  conclusion  is  reached  that  over  the  world 
the  average  annual  amount  of  rock-material  dissolved  and  carried  off  by  rivers  is  about 
100  tons  per  square  mile,  of  which  about  $  is  probably  calcium  carbonate,  A  calcium 
sulphate,  7  tons  silica,  4  tons  each  magnesium  carbonate  and  sulphate  and  sodium  chloride, 
and  6  of  alkaline  carbonates  and  sulphates.  The  annual  amount  of  detritus  brought 
down  by  the  Danube  is  about  -^ ^  of  the  water,  or  three  times  the  amount  of  solids  in 
solution.  Taking  the  amount  of  solids  removed  mechanically  at  six  times  that  in  solu- 
tion, the  total  annual  amount  of  denuded  material  for  the  globe  would  be  600  tons  per 
square  mile. 

While  the  land  loses  through  erosion,  the  gain  of  the  oceanic  depressions,  or  of  its 
borders,  is  exceedingly  small.  C.  G.  Forshey,  after  stating  that  the  Gulf  of  Mexico  has 
an  area  of  600,000  square  miles,  an  average  depth  of  4920  feet,  and  is  about  85,000,000,- 
000,000,000  (85  quadrillions)  of  cubic  feet  in  contents ;  that  its  whole  drainage  area  is 
2,161,890  square  miles,  and  the  amount  of  fresh  water  it  receives  from  this  area  is  37-78 
trillions  of  cubic  feet ;  adds  that  if  empty,  it  would  take  its  tributary  rivers  at  this  rate 
2250  years  to  fill  it  with  water,  or  the  Mississippi  alone,  4000  years.  Consequently,  if  all 
the  rivers  contribute  on  an  average  2^00  tneir  ^u^k  of  detritus,  it  would  take  nearly 
6,000,000  years  to  grade  the  depression  up  to  the  sea  level,  or  for  the  Mississippi  alone,  about 
11,000,000  years.  This  statement  assumes  that  the  bottom  does  not  sink  under  the  load. 

The  quantity  of  wood  brought  down  by  some  American  rivers  is  very 
great.  The  well-known  natural  "  raft,"  obstructing  Red  River,  had  a  length, 
in  1854,  of  13  miles,  and  was  increasing  at  the  rate  of  one  and  a  half  to  two 
miles  a  year,  from  the  annual  accessions.  The  lower  end,  which  was  then 
53  miles  above  Shreveport,  had  been  gradually  moving  up  stream,  from 
the  decay  of  the  logs,  and  formerly  was  at  Natchitoch.es,  if  not  still 
farther  down  the  stream.  Both  this  stream  and  others  carry  great  numbers 
of  logs  to  the  delta. 

DISTRIBUTION.  —  The  transported  material  of  rivers  is  distributed  — 

(1)  Along  the  channel,  forming  sand-flats,  and  mud-flats,  and  deposits 
also  in  the  lakes  of  the  drainage  area. 

(2)  Over  the  flood-grounds,  supplying  what  these  may  annually  lose  dur- 
ing floods,  and  adding,  in  places,  to  their  height,  thus  making  fluvial  or  allu- 
vial formations,  and,  about  lakes,  lacustrine  formations. 

(3)  About  the  mouths  of  tideless  rivers,  making  deltas  on  the  sea  border 
and  on  lakes. 

(4)  About  the  mouths  of  tidal  rivers,  making  estuary,  shore  and  off-shore 
deposits.     This  last  subject  is  deferred  to  the  chapter  on  the   Work   of 
the  Ocean. 


192  DYNAMICAL   GEOLOGY. 

(1)  General  distribution.  —  The  material  carried  down  by  a  river  is  only  to 
a  very  small  extent  gathered  by  the  main  stream  from  its  head  sources.  The 
upper  contributions  are  nearly  all  left  high  up  the  valley,  and  only  little 
of  the  lighter  sediment  received  usually  continues  far  down  the  main  trunk. 
A  river  has  many  contributors  along  its  course,  each  pouring  in  coarser  or 
finer  sediment  from  cobble-stones  to  silt,  according  to  its  pitch,  velocity,  and 
resources ;  and  what  each,  in  succession,  contributes,  the  trunk  stream  dis- 
tributes and  deposits  about  and  below  the  place  where  received,  dropping  it 
near  by  if  it  is  coarse,  carrying  it  011  for  awhile  if  fine.  Thus  from  the  suc- 
cessive depositions  of  the  material  of  the  successive  tributaries,  the  trunk 
stream  produces  its  "fluvial  formations."  Such  a  formation  may  therefore 
be  continuous  through  the  whole  length  of  the  river-portion  of  the  stream, 
but  be  exceedingly  varied  in  constitution.  In  addition  to  all  this,  the  river 
has  often,  in  its  course,  steep  rocky  shallows  and  deep  lake-like  portions,  if 
not  true  lakes ;  and  thereby  the  waters  may  have  all  grades  of  velocity  to 
the  gentlest.  These  different  styles  of  flow  will  be  continued  to  some  extent 
through  ordinary  floods,  notwithstanding  the  generally  quickened  move- 
ment; and  this  is  another  source  of  diversity  in  the  fluvial  depositions,  since 
deposition  is  dependent  on  rate  of  flow,  and  the  slow  lake-like  waters  deposit 
fine  material  over  their  flood-grounds  as  well  as  along  their  banks  and 
bottom.  No  pebbles  or  stones  above  a  region  of  sleepy  waters  could  get 
across  to  join  a  pebbly  region  made  below  by  a  tributary ;  they  must  be  ground 
up  for  transportation  and  then  take  their  chance  with  other  fine  sediment. 

Depositions  are  made  along  broad  channels  when  the  flow  is  not  rapid 
enough  throughout  the  breadth  to  sweep  all  the  transported  material  down 
stream.  The  chief  current  (or  currents)  makes  its  own  deep,  often  stony, 
passage-way ;  but  either  side  the  detritus  drops  because  of  the  slower  flow, 
and  raises  the  bottom  more  or  less,  or  to  the  surface,  according  to  the  degree 
of  slowness,  the  eddying  currents,  and  the  supply  and  fineness  of  detritus. 
The  trend  of  the  shores,  pitch  of  the  bottom,  and  other  causes,  locate  the 
swifter  currents  in  the  channel,  and  thereby  tend  to  locate  the  banks  or  reefs. 
A  stranded  log  may  change  the  course  of  the  former,  and  thereby  the  posi- 
tions of  the  latter.  The  lodging  of  drift-wood  on  a  sand-bar  may  serve  to  in- 
crease the  accumulation  over  it,  and  so  change  the  bar  into  a  wooded  island. 
But  high  floods  rob  the  bars  at  the  same  time  that  they  add  to  them,  or  they 
may  sweep  them  away,  even  if  already  an  island,  to  form  other  bars  and 
islands.  They  push  along  the  movable  detritus  of  the  river's  bottom,  and 
also  drop  more  to  keep  it  generally  at  the  old  level.  Thus  all  is  movement 
and  change  along  a  river's  channel,  and  deposits  of  all  degrees  of  fineness  or 
coarseness  may  be  of  simultaneous  origin. 

When  two  rivers  unite,  one  often  makes  a  shoal  in  the  other,  by  throwing 
a  bar  across  the  channel  through  the  descending  detritus  of  flood-waters. 
The  waters  of  the  upper  Mississippi  are  pushed  to  the  opposite  shore  by  the 
contributions  of  a  tributary,  and  a  deep,  still-water,  navigable  area  is  made 
above  the  junction,  and  rapids  below  it.  Further,  the  tributary,  if  not  in 


WATER   AS   A   MECHANICAL   AGENT.  193 

flood  at  the  same  time,  will  have  its  mouth  filled  with  sand-bars  by  the 
greater  river,  and  often,  also,  in  spite  of  its  floods.  This  subject  is  well 
illustrated  in  Reports  on  the  Mississippi  and  its  Tributaries  by  General 
G.  K.  Warren. 

Sand-bars;  obliquely  laminated  structure.  —  A  sand-bar,  as  shown  by  Gen- 
eral Warren,  has  usually  a  slight  pitch  up  stream  and  a  steep  one  at  the  down- 
stream extremity.  The  sand  is  carried  on  until  the  crest  is  reached,  when 
it  falls  over  and  stops  in  the  still  water  below.  The  stratification  will  corre- 
spond with  the  surface ;  and  as  the  sand-bar  extends  itself  down  stream  by 
the  additions  to  its  extremity,  the  pitch  of  the  down-stream  extremity  will 
determine  oblique  bedding  parallel  with  it.  The  pushing  of  detritus  along 
the  bottom  of  a  river  must  result  in  similar  oblique  bedding.  But  in  both 
cases,  oblique  deposition  will  be  followed  by  deposition  in  horizontal  beds 
when  the  floods  are  declining,  so  that  combinations  of  the  two,  often  of  a 
very  irregular  character,  should  exist  in  such  deposits. 

(2)  Over  the  flood-grounds.  —  The  flood-grounds  or  river-flats  are  under 
water  only  in  times  of  floods.  As  the  water  rises  in  the  channel,  the  velocity 
slowly  increases;  finally,  where  too  great  to  be  further  withstood  by  the 
earthy  banks,  the  waters  spread  laterally  to  the  limits  of  the  flats.  They 
lose  in  velocity,  and  drop  more  or  less  of  the  material  transported,  resting 
long  after  the  flood  ceases  for  such  deposition  wherever  the  Surface  is  low. 
At  the  same  time,  the  upper  or  surface  portion  of  the  flood-waters  may  shear 
off  any  accumulations  above  the  general  level,  left  by  a  former  higher  flood, 
or  may  work  with  the  outer  margin  to  extend  the  limits  of  the  flood-grounds. 
The  flood-grounds  may  thus  lose  from  their  surface,  and,  in  parts,  be  cut 
away  to  open  new  channels ;  but  they  generally  gain  as  much  as  they  lose 
or  more.  Along  the  sides  of  the  channel  they  are  often  built  up  higher  than 
elsewhere,  thus  making  high  banks  which  may  be  emerged  during  an  ordinary 
flood.  This  raising  of  the  margin  takes  place  because  of  the  deposition  from 
loss  of  velocity  by  friction  against  the  banks,  and  because  logs  and  debris 
of  other  kinds  are  here  stranded ;  the  debris  serves  to  impede  the  velocity 
still  more  and  thus  is  buried  by  the  sediment.  Further,  an  emerging  bank 
often  catches  floating  seed  and  grows  shrubbery.  These  raised  banks  are 
most  common  along  the  lower,  less  vigorous  portions  of  a  river.  They  give 
the  flood-plains  a  slope  outward  on  one  or  both  sides.  Along  the  lower  Mis- 
sissippi the  pitch  from  the  river  amounts,  on  an  average,  to  seven  feet  for  the 
first  mile.  (H.  &  A.)  As  above  explained,  the  deposits  of  the  flood-grounds 
may  be  the  finest  of  silt,  or  the  coarsest  of  gravel  and  stones,  according  to 
the  region  and  the  pitch  of  the  stream.  The  course  of  a  tributary  from  a 
mountain  region  over  the  flood-plain  of  the  main  stream  may  throw  into 
and  across  the  earthy  or  sandy  flats  of  the  latter  a  wide  thickening  bed 
of  stones  or  gravel. 

A  flood-ground  is  properly  the  surface  of  a  terrace ;  and  it  is  the  lowest 
of  the  terraces  where  a  valley  has  several.  Terraces  occur  along  nearly  all 
DANA'S  MANUAL  — 13 


194 


DYNAMICAL   GEOLOGY. 


river  valleys  in  the  northern  half  of  the  United  States,  and  in  some  of  the 
southern  half.  Fig.  180  represents  the  terraces  in  the  Connecticut  valley, 
south  of  Hanover,  N.H. 

The  fluvial  beds  in  these  terraces  consist  of  sand,  gravel,  or  clay ;  and 
ordinarily  the  stratification  is  very  distinct.  The  sand-beds  often  have  the 
cross-bedded  stratification,  illustrated  on  page  93,  and  in  some  places  the 
flow-and-plunge  structure. 

The  height  of  flood-plains  in  a  valley  is  determined  approximately  by  the 
height  of  the  floods.  Floods  raised  to  different  levels  would  tend  to  make 
plains  at  different  levels,  or  terraces,  in  the  valleys  of  a  country.  If  a  high 
flood-level  had  thus  made  a  high  flood-plain  or  terrace,  other  terraces  might 

180. 


Terraces  on  the  Connecticut  River,  south  of  Hanover,  N.H.     R.  Bakewell,  '49. 

be  formed  at  different  levels  below  this  during  the  decline  of  the  flood,  if  it 
were  slow  and  intermittent  in  progress,  by  lateral  removal  of  material,  or  by 
new  depositions.  The  enormous  floods  from  the  melting  ice  of  a  glacial 
era  would  be  subject  to  just  such  slowly  progressing  and  intermittent  decline, 
because  of  the  thickness  of  the  ice,  and  its  long  continuance  about  the 
mountains,  and  might,  therefore,  leave  the  valleys  with  one  or  several 
ranges  of  terraces. 

1.  Alluvial  cones.  —  The  deposit  of  a  rapid  tributary  at  the  base  of  the 
ridge  it  descends,  where  it  meets  the  broad  plain  of  the  valley,  piles  up  and 
makes  a  low  elevation  which  is  called  an  alluvial  cone.  The  steeper  cones  are 
made  by  torrents  at  the  base  of  rapid  declivities,  and  have  an  angle  of  10°  or 
more,  and  those  of  large  streams  spread  away  at  a  very  small  angle,  often  1° 
or  less,  and  usually  terminate  in  the  main  river  of  the  valley,  or  a  lake,  with 
the  form  approximately  of  a  delta.  Figs.  181,  182  represent  such  cones 
from  the  upper  Indus  Basin,  described  and  figured  by  F.  Drew  (1873). 


WATER   AS   A  MECHANICAL  AGENT. 


195 


The  torrential  stream  in  its  flood-time  cuts  channels  through  the  cone  that 
later  quiet  depositions  fill  up.  In  Fig.  182  a  cone  is  encroached  upon  (near  d) 
by  the  river.  Alluvial  cones,  of  great  size  and  low  angle,  occur  at  the  base  of 
the  mountains  in  the  Great  Basin  and  in  some  other  parts  of  the  Eocky  Moun- 
tain region,  and  have  been  described  by  Gilbert  (1877-1890),  Button  (1880), 


181. 


182. 


Alluvial  cone  or  fan-talus  of  upper  Indus  Basin. 


Triple  alluvial  cone,  ibid.     Drew. 


and  I.  C.  Russell  (1885).  The  gravelly  deposits  of  this  kind  at  the  mouth  of 
tributaries  in  the  Connecticut  valley  and  elsewhere  were  called  deltas  by 
E.  Hitchcock,  and  the  terraces  over  the  surface  either  side  of  the  stream, 
delta-terraces. 

2.  Lcess.  — The  terrace-like  deposits  along  portions  of  the  valleys  of  the 
Rhine,  Danube,  and  Mississippi  consist  of  loamy  earth  called  loess,  which  is 
peculiar  in  its  absence  of  stratification,  and  often  also  in  its  vertical  surfaces 
of  fracture.  They  have  remarkable  extent  along  the  Hoang  Ho  in  China. 
The  accompanying  sketch,  from  Richthofen's  great  work  on  China  (1877), 
shows  its  usual  landscape  features.  Erosion  reduces  portions  of  its  margin 
to  a  collection  of  towers,  peaks,  and  deep  and  narrow  labyrinthine  passages ; 
and  human  contrivance  makes  dwelling-places  by  excavation.  The  thickness 
is  stated  to  be  in  some  places  2000  to  2500  feet.  The  material  is  a  brownish 
yellow  earth,  containing  land-shells  and  calcareous  concretions.  It  occurs  at 
several  different  levels  along  the  river,  100  to  250  feet  within  175  miles  of 
the  sea ;  next,  beyond  a  region  of  mountains,  1800  to  3500  feet ;  after  passing 
another  mountain  region,  4500  to  5800  feet ;  and  it  is  stated  to  extend  to 
the  most  western  sources  of  the  river  over  900  miles  from  the  coast.  The 
river  at  these  levels,  as  in  other  cases  of  loess  deposition,  was  probably  lake- 
like.  Long-sustained  floods  of  the  rivers  in  the  mountains  from  melting 
glaciers  are  one  explanation  of  the  source  of  the  material.  Eolian  drifting  of 
dust  from  the  salt-steppes  of  Siberia  is  Baron  von  Richthofen's  theory,  which 
the  absence  of  a  wind-drift  structure  renders  improbable. 

Deposits  occur  in  the  Great  Basin  resembling  the  loess  in  absence  of  stratification  and 
other  characters,  which  are  called  adobe  by  Mr.  I.  C.  Russell,  from  the  name  for  sun- 
burnt brick,  because  this  material  is  used  for  making  the  brick.  It  has  usually  a 
yellowish  color,  and  is  more  or  less  calcareous.  It  is  described  as  a  result  of  the  wash 


196 


DYNAMICAL  GEOLOGY. 


and  deposition  of  the  ephemeral  streams  and  the  thousands  of  little  rills  that  are 
occasionally  at  work  over  the  surface  of  the  dry  regions :  the  annual  precipitation  is  less 
than  20  inches.  The  deposits  in  some  places  are  hundreds  of  feet  in  depth.  The 
calcareous  portion  is  attributed  to  land-shells.  It  is  various  in  composition,  containing 
1  to  14  per  cent  of  alumina,  19  to  67  of  silica,  and  2  to  5  of  water,  with  3  to  60  per  cent 
of  calcium  carbonate. 

183. 


Loess  formation  on  the  Hoang  Ho,  in  the  province  of  Shan-Si,  China.    Richthofen. 

Fine  mud-like  deposits  are  formed  over  the  Great  Basin  in  temporary  lakes,  called 
playas,  produced  by  the  overflow  of  rivers,  the  material  of  which  is  related  to  the  preced- 
ing. The  mud  contains  more  or  less  of  the  saline  ingredients  of  the  evaporating  waters. 

(3)  Delta-formations.  — The  larger  part  of  the  detritus  of  a  river  is  carried 
to  the  ocean,  or  lake,  into  which  it  empties ;  and  it  goes  to  form  more  or  less 
extensive  flats  about  the  mouth  of  the  stream.  Such  flats,  when  large  and 
intersected  by  a  net-work  of  water-channels,  are  called  deltas;  they  are  river- 
made,  and  reach  a  large  size  only  where  the  tides  are  quite  small,  or  are 
altogether  wanting. 

The  spread  of  a  river  into  a  delta  at  its  mouth  is  a  consequence  of  its 
enfeebled  or  decrepit  state.  Deposition  is  excessive  and  becomes  an  obstruc- 
tion to  the  flooded  river,  and  consequently,  besides  keeping  open  one  or  two 
main  channels,  the  waters  cut  new  channels  at  flood-times,  which  may  partly 
disappear  and  become  replaced  by  others  in  future  floods.  The  surface 
thereby  becomes  intersected  by  many  lines  of  sluggish  waters,  small  and 
large,  which  flood-time  puts  into  temporary  activity.  The  deposits  have  a 
slight  slope  seaward,  and  thus  approximate  in  character  to  an  alluvial  cone 
(Gilbert),  although  a  consequence  of  the  floods  of  a  stream  in  decrepitude, 
and  not  of  one  in  a  torrential  or  vigorous  state.  Through  the  flood-deposi- 


WATER   AS  A  MECHANICAL  AGENT. 


197 


tions  over  the  various  parts  thus  carried  forward,  along  with  the  aid  of 
encroaching  vegetation,  a  large  portion  of  a  delta  may  become  emerged. 
More  than  two  thirds  of  the  Mississippi  delta  in  the  ordinary  state  of  the 
river  are  above  water ;  and  over  this  part  are  plantations  of  rice,  sugar,  and 
cotton,  and  cypress  forests.  The  area  of  actually  productive  land  within  it 
is  22,920,320  acres;  of  reclaimable  land,  35,813  square  miles.  But  if  the 
river  were  unrestrained  by  levees,  the  highest  floods  would  fill  the  alluvial 
basin  and  make  a  sea  600  miles  long,  60  miles  in  mean  width,  and  12^  feet 
in  mean  depth.  (C.  G.  Forshey,  1873.)  The  force  of  the  flood-waters  of  the 
Mississippi  is  so  great,  and  the  amount  of  transported  detritus  so  large,  that 
the  stream  pushes  out  its  long  arms  into  the  Gulf,  by  its  method  of  deposit- 
ing load  after  load ;  and  it  is  still  continuing  its  elongations  at  the  extremities 
of  the  passes. 

184. 


Delta  of  the  Mississippi. 


The  shallow  waters  within  one  to  three  miles  of  the  main  channel  at  the  mouth  of  the 
Mississippi  River  (see  map)  are  dotted  with  what  are  called  mud-lumps,  —  convex  or 
low  conical  elevations,  sometimes  100  feet  or  more  in  diameter,  showing  their  tops  at 
the  surface.  They  originate  in  upheavals  of  the  soft  but  tough  bottom.  Once  formed, 
they  discharge  mud  from  the  top,  which  gives  to  the  material  of  the  low  cone  the  structure 
of  a  volcanic  cone,  the  successive  layers  being,  however,  of  mud,  and  but  a  fraction  of  an 
inch  thick.  They  finally  collapse  ;  and  then  the  cavity  of  the  cone  sometimes  becomes  the 
site  of  a  pool  of  salt-water,  like  the  lake  in  an  extinct  volcano.  They  are  formed,  accord- 
ing to  Professor  E.  W.  Hilgard  (from  whose  excellent  description  in  the  American 
Journal  of  Science,  1871,  the  facts  here  given  are  cited,  and  who  adopts,  in  the  main 


198  DYNAMICAL   GEOLOGY. 

point,  the  view  of  Lyell),  through  the  pressure  of  the  surface  deposits  on  a  layer  of  mud 
which  overlies  the  Port  Hudson  clay,  or  older  alluvium  of  the  river.  Some  carbo-hydro- 
gen  gas  is  given  out,  arising  from  the  decomposition  of  animal  or  vegetable  matters  in 
the  mud.  The  mud-discharges  tend  to  increase  the  shallowness  of  the  waters  and  push 
out  the  land  into  the  Gulf  waters.  Mr.  Hilgard  states,  in  1871,  that  Morgan's  mud-lump, 
in  the  marsh  of  Southwest  Pass,  had  been  active  for  25  years,  and  during  the  time  the 
bars  had  moved  gulfward  a  mile  and  a  half.  He  closes  his  paper  with  a  remark  (vol.  i. 
435)  relating  to  the  distance  to  which  the  Southwest  Pass  must  extend  in  order  that  there 
shall  be  no  danger  of  mud-lumps  within  the  channel.  The  Eads  jetties  have  since  then 
been  made  along  this  pass,  in  order  to  give  it  greater  depth.  It  has  secured  the  depth ; 
but  with  danger  from  this  source  still  existing,  as  Professor  Hilgard  has  observed. 

According  to  Humphreys  and  Abbot,  the  outer  crest  of  the  bar  of  the  Southwest 
Pass,  the  principal  one  of  the  Mississippi,  advances  into  the  Gulf  338  feet  annually,  over  a 
width  of  11,500  feet ;  and  the  erosive  power  is  only  about  TL  of  its  depositing  power. 
The  depth  of  the  Gulf,  where  the  bar  is  now  formed,  being  100  feet,  the  profile  and  other 
dimensions  of  the  river,  in  connection  with  the  above-mentioned  rate  of  deposit,  give  for 
the  difference  between  the  cubical  contents  of  yearly  deposit  and  erosion  255,000,000 
cubic  feet,  or  a  mass  1  mile  square  and  9  feet  thick  :  this,  therefore,  is  the  volume 
of  earthy  matter  pushed  into  the  Gulf  each  year  at  the  Southwest  Pass.  The  quantities  of 
earthy  matter  pushed  along  by  the  several  passes  being  in  proportion  to  their  volumes  of 
discharge,  the  whole  amount  thus  carried  yearly  to  the  Gulf  is  750,000,000  cubic  feet, 
or  a  mass  1  mile  square  and  27  feet  thick.  As  the  cubical  contents  of  the  whole  mass 
of  the  bar  of  the  Southwest  Pass  are  equal  to  a  solid  1  mile  square  and  490  feet  thick, 
it  would  require  55  years  to  form  the  bar  as  it  now  exists,  or,  in  other  words,  to  establish 
the  equilibrium  between  the  advancing  rates  of  erosion  and  deposit.  Hilgard  has  shown 
that,  about  New  Orleans,  the  modern  alluvium  has  a  depth  of  only  31  to  56  feet,  there 
existing  below  this  the  alluvial  clay,  etc.,  of  the  Port  Hudson  group. 

The  delta  of  the  Hoang  Ho  (Yellow  River)  extends  along  the  coast  from  near  Peking, 
on  the  north  beyond  the  Pei  Ho,  to  Hung-tse  Lake,  on  the  south,  where  it  joins  the 
plains  of  the  Yang-tse-Kiang.  The  distance  is  400  miles  ;  but  the  mountainous  coast- 
province  of  Shan-Tung  is  to  be  excluded.  From  the  coast,  the  delta  extends  westward 
for  300  miles.  The  river  is  here  useless  for  navigation.  The  whole  delta  region  would  be 
under  water  during  flood  seasons  except  for  drainage  by  artificial  dikes  and  canals  of 
great  length;  and  these  have  required  constant  supervision.  At  long  intervals,  the 
great  river  has  broken  loose  and  swept  over  the  immense  area  with  devastating  floods, 
and  ended  its  mad  career  with  change  of  channel  from  the  river  Pei  Ho,  or  some  place 
near  it,  on  the  north,  to  a  southeast  route  ;  or  the  reverse.  In  1820  it  occupied  a  southeast 
channel,  emptying  into  the  Yellow  Sea,  near  latitude  33£°  N.  By  1858  this  channel  was 
dry ;  and  after  some  years  of  uncontrolled  waters,  it  took  a  new  channel  into  the  Gulf 
of  Pe-chi-li,  300  miles  north.  In  the  autumn  of  1887,  a  new  break  occurred  near  Kai 
Fung,  in  Ho-Nan  ;  but  the  waters  instead  of  resuming  the  old  channel  which  they  left  after 
1852  took  a  course  south  from  Kai  Fung  to  the  Cha,  70  miles,  and  then  struck  off  east- 
southeastward  to  the  Hoei  Ho  and  the  sea.  The  Chinese  have  succeeded  in  leading  off  the 
upper  part  of  the  wandering  waters  into  the  old  channel  mentioned  above,  leaving  the  more 
southern  part  in  its  new  channel.  The  first  of  such  changes  recorded  in  Chinese  annals 
occurred  in  2293  B.C.  ;  a  second,  owing  to  Chinese  care,  not  until  602  B.C.  Several  have 
occurred  since.  The  Mississippi  has  its  disastrous  floods,  but  no  chance  for  such  changes. 

(4)  Lakes. — The  discharge  of  lakes,  like  that  of  rivers,  is  (1)  evapo- 
rational  or  upward;  (2)  gravitational  or  downward;  and  (3)  surficial,1  sea- 

1  The  word  superficial  is  too  various  in  its  significations  to  express  the  right  idea.  Surficial 
is  like  surface  in  having  for  its  prefix  the  French  abbreviation  sur  in  place  of  super. 


WATER    AS    A    MECHANICAL   AGENT.  199 

ward.     They  either  belong  to  the  continental  river  systems,  and  are  river- 
system  lakes,  or  they  are  confined  or  imprisoned  lakes. 

1.  Imprisoned  lakes  fail  of  the  third  method  of  discharge  and  are  rela- 
tively few  in  number.     They  lie  in  basins  or  depressions  that  had  been  made 
or  left  in  the  surface  by  orographic  movements,  or  had  become  cut  off  in 
some  way  from  a  river  system,  or  possibly  where  the  rocks,  having  little 
firmness,  had  been  excavated  by  former  glacier  action.     Some  of  small  size 
occupy  craters  of  extinct  volcanoes.     The  Caspian  Sea,  Dead  Sea,  Great  Salt 
Lake  of  Utah,  and  lakes  in  the  Great  Basin,  are  examples.     They  are  most 
likely  to  exist  under  dry  climates,  where  the  supply  of  water  is  small  and 
evaporation  large ;  and  they  may  vary  from  dry  beds  to  lakes  in  the  chang- 
ing climates   of  the  year.     Some  imprisoned  lakes  have  had  surficial  dis- 
charge in  former  eras.     A  confined  river  system  usually  supplies  the  waters, 
and  carries  in  what  can  be  gathered  from  the  rocks  around  by  solution  and 
otherwise,  as  explained  on  page  118. 

2.  Lakes  connected  with  river  systems  occur  in  all  climates  and  latitudes, 
and  at  various  heights.     They  are  often  situated  in  lines  or  clusters  over 
the  nearly  level  summit  region  of  a  Continental  Interior,  where  the  great 
rivers  are  gathering  waters  and  deciding  on  their  courses.     They  sometimes 
occupy  profound  depressions   in  the  earth's   crust,  like  the  Great   Lakes 
of  North  America,  or  follow  the  nearly  level  median  line  of  continental 
drainage,  as  the  Winnipeg  series  of  British  America. 

The  basins  may  be  a  result  of  geosynclinal  movements,  like  that  of  Lake 
Superior ;  or  otherwise  of  orographic  origin,  as  the  intermontane  lake  basins 
of  many  mountain  regions ;  and  even  a  consequence  of  the  feeblest  flexures 
of  the  earth's  crust.  They  have  commonly  been  made  within  the  area  of  a 
river  system  by  damming  with  transported  material.  Unusual  floods  may 
make  barriers  by  local  depositions  ;  more  easily,  tributaries  may  throw  across 
a  valley  dams  that  have  a  degree  of  permanence ;  still  more  effectively,  ice 
may  carry  along  gravel  and  sand  and  block  the  deep  and  narrow  channel ;  or 
better,  in  regions  of  glaciers,  more  formidable  deposits  of  drift  may  make 
obstructions  in  valleys  and  give  outlines  to  many  lakes  over  nearly  level 
regions.  After  a  period  of  elevation  when  the  valleys  were  excavated  to 
great  depths,  a  period  of  lower  level  may  have  come,  in  which  the  transport- 
ing waters  were  in  great  force  and  made  obstructing  deposits,  especially  when 
water  and  gravel  were  afforded  in  vast  quantities  for  the  purpose  by  a  melt- 
ing glacier.  Lake  Geneva,  in  Switzerland,  45  miles  long  and  1095  feet  deep, 
the  surface  1230  feet  above  tide-level,  is  supposed  to  have  been  made  in  the 
way  last  mentioned ;  and  even  also,  Lago  Maggiore,  of  northern  Italy,  which, 
although  only  three  miles  wide,  is  2613  feet  deep,  with  1920  of  this  below  the 
sea.  Another  view  attributes  the  depth  of  Lake  Geneva  to  a  subsidence  of 
the  lake  bottom  since  the  Glacial  period. 

Further,  a  large  river  in  its  more  aged  or  decrepit  portion  may  so  wall 
itself  in  and  raise  its  bed  by  depositions  either  side  of  and  along  its  chan- 
nel, that  every  flood  makes  temporary  lakes;  and  extraordinary  floods  may 


200  DYNAMICAL   GEOLOGY. 

carry  off  waters  that  excavate  a  course  through  the  alluvium  to  neighboring 
depressions  and  thus  make  a  more  permanent  lake. 

Salton  Lake,  in  the  southeastern  corner  of  California,  130  miles  long  by  40  in  greatest 
breadth,  resulted,  in  July,  1891,  from  the  overflow  of  the  Colorado  River  on  the  west  side 
below  Yuma.  The  alluvial  region  either  side  of  the  river  between  Yuma  and  the  head  of 
the  California  Gulf,  50  miles  distant,  had  been  gradually  built  up  by  river  depositions, 
until  a  large  depression,  Coahuila  valley,  now  300  feet  below  the  sea  where  deepest,  had 
been  separated  from  the  head  of  the  gulf  and  left  as  a  nearly  dry  desert  basin.  The 
flooded  waters,  pressing  westward  along  the  westward  course  of  New  River,  succeeded  in 
passing  the  low  summit  level,  and  then  quickly  excavated  a  way  to  the  depression  and  filled 
it.  Owing  to  the  hot  and  extremely  dry  climate,  evaporation  will  sooner  or  later  make  it 
an  empty  lake-basin,  as  it  was  essentially  before.  The  river  at  Yuma  is  about  150  feet 
above  the  gulf.  Nearly  100  miles  north  of  the  Salton  Lake  is  Death  Valley,  225  feet 
below  the  sea,  also  situated  in  the  line  of  the  California  Gulf. 

W.  P.  Blake  traveled  over  the  desert  in  1853  (Geol.  Eeconn.  CaL,  4to,  1858),  and 
describes  it  as  having,  in  general,  a  barren,  clayey  surface,  with  some  saline  springs  along 
the  margin  and  elsewhere.  On  the  rocks  of  the  shore,  there  was  a  thick  horizontal  belt 
of  whitish  calcareous  tufa  about  15  feet  (where  examined)  above  the  level  of  the  desert, 
indicating  a  former  water  level,  and  proving  that  the  desert  was  the  dry  basin  of  a  former 
lake.  He  found  that  the  Indians  had  a  tradition  of  the  existence  of  a  great  lake  filled 
with  fish ;  of  its  slowly  drying  up,  and  of  a  sudden  return  of  the  waters,  when  many 
were  drowned.  The  recent  event  is  evidently  not  the  only  one  of  the  kind  in  the  region. 

Other  lake-basins  have  been  made  by  glacier-damming  (page  238),  and 
possibly,  as  above  stated,  by  glacier-excavation.  Still  others  of  small  size 
are  a  result  of  underminings,  especially  through  removals  of  clay-beds  by 
pressure  ;  others  have  come  from  a  damming  against  the  sea  by  beach-made 
deposits  (page  224),  converting  inlets  into  sea-border  basins. 

The  large  lakes  of  the  world,  after  the  Caspian,  are  the  Great  Lakes  of  North  America, 
Lake  Baikal  in  Asia,  and  Lake  Victoria  in  east  Central  Africa.  The  map,  Fig.  185,  gives 
the  positions  of  the  American  Great  Lakes,  and  the  line  of  greatest  depth,  the  deepest 
point  in  each,  and  also  the  limits  of  the  several  drainage  areas.  Lake  Superior  has  an 
area  of  31,200  square  miles  ;  Huron,  of  23,800  square  miles  ;  Michigan,  of  22,450  ;  Erie, 
of  9960 ;  Ontario,  of  7240.  The  heights  of  the  water  above  mean  sea  level  are :  Lake 
Superior,  601-8' ;  Huron  and  Michigan,  581-3' ;  Erie,  572-9' ;  Ontario,  246-6'.  The  section, 
Fig.  186,  shows  their  depths,  and  the  extension  below  the  sea  level.  (Schermerhorn, 
Amer.  Jour.  Sci.,  1887.)  Lake  Chainplain  is  402'  deep,  300'  of  it  below  the  sea  level. 

The  heights  of  some  other  American  lakes  are  as  follows :  Winnipeg,  630' ;  Lake  of 
the  Woods,  1640' ;  Great  Salt  Lake,  4218' ;  Yellowstone  Lake,  7788' ;  Shoshone  Lake, 
7870';  Great  Bear  Lake,  5931'. 

The  Caspian  has  an  area  of  170,000  square  miles,  a  depth  of  500',  and  descends  90' 
below  the  sea  level.  Lake  Baikal  in  Siberia  (really  among  the  high  Altai  Mountains 
and  near  Central  Asia)  is  397  miles  long,  54  miles  in  maximum  width,  and  has  a 
depth  in  some  parts  of  over  300  fathoms,  nearly  500'  of  which  is  below  the  sea  level.  The 
great  African  Lake,  Victoria,  has  an  area  of  about  27,000  square  miles,  and  is  3300  feet 
above  the  sea  level.  The  Assat  Lake  lies  in  a  depression  east  of  Abyssinia,  600'  below  the 
level  of  the  Red  Sea,  and  is  salt. 

Rivers  tend  to  obliterate  the  lakes  along  them  in  two  ways  :  by  the  depo- 
sition of  detritus  in  their  still  waters  and  along  their  borders,  and  by  erosion 


WATER   AS   A   MECHANICAL    AGENT. 


201 


at  the  outlet  where  the  stream  resumes  its  relatively  rapid  flow.  The  final 
result  when  reached  is  the  conversion  of  the  bed  of  a  lake  into  a  river 
channel. 

185. 


SKETCH  OF  THE 

NORTHERN  AND 

NORTHWESTERN  LAKES 

Limit  of  Drainage  Areas 

\         Line  of  Deepest  Water. 

^Deepest  Sounding  # 


Map  of  the  Great  Lakes.    L.  Y.  Schermerhorn,  '87. 


The  smaller  lakes  are  very  feeble  workers,  and  hence,  owing  to  gentle 
trituration  by  the  little  waves,  the  shores  are  often  muddy.     Theoretically 


186. 


Longitudinal  sections  of  the  lakes  on  the  line  of  deepest  water.     Schermerhorn,  '87. 

the  waters  of  the  lakes  over  high  plateaus,  like  those  of  the  head  waters  of  the 
Mississippi,  have   great  energy;  but  they  usually  lie  without  a  chance  to 


202  DYNAMICAL   GEOLOGY. 

show  it.  Occasionally  a  lake  bursts  its  bounds,  and  produces  in  a  few  hours 
the  devastating  effects  of  the  most  violent  of  torrents.  But  such  effects  are 
rare,  except  where  man  has  interfered. 

The  large  lakes  have  many  of  the  characteristics  of  the  ocean.  The 
wind,  waves,  and  currents  are  effective  agents  of  wear  and  deposition  along 
the  shores,  and  about  bays  and  the  mouths  of  rivers. 

The  waves  work  landward  on  shelving  shores,  as  along  the  sea  border, 
while  a  littoral  current  usually  runs  parallel,  or  nearly  so,  with  the  coast ; 
and  between  the  two  the  depositions  of  sand  and  making  of  beaches  and 
sand-bars  take  place. 

The  nearly  total  absence  of  tides  makes  marked  differences  in  the 
effects.  The, change  of  level  in  seashore  action  with  the  tidal  movements 
fails.  Abrasion  sets  back  the  cliffs,  but  makes  a  sloping  surface  at  their 
base. 

The  tide  on  Lake  Michigan  has  a  range  of  three  inches  at  spring  tides 
and  li  at  neap  tides.  Large  oscillations  of  the  surface  are  produced  by  storm 
winds,  and  lighter  ones  by  floods  in  the  region.  On  Lake  Erie,  at  Buffalo, 
the  difference  between  the  levels  produced  by  two  gales,  one  from  the  S.  W., 
and  the  other  off  shore,  from  the  N.  E.,  was  15|-  feet  (Whittlesey).  Small 
but  short  tide-like  changes  of  level,  called  seiches,  a  few  inches  in  height, 
observed  on  Lake  Geneva  and  other  Swiss  lakes,  are  attributed  by  Forel  to 
local  variations  of  atmospheric  pressure  —  an  impulse  so  given  producing 
a  long-continued  series  of  oscillations.  Larger  seiches  are  supposed  to  be 
due  to  earthquake  shocks. 

For  a  thorough  discussion  of  lacustrine  methods  of  work  under  varying  conditions  of 
levels,  see  the  Memoir  of  G.  K.  Gilbert  on  Lake  Bonneville,  U.  S.  G.  S.,  4to,  1890. 

Past  geological  ages  had  their  fresh-water  lakes  as  well  as  rivers.  But 
the  great  lakes  and  rivers  of  the  world  belong  to  later  history,  the  era 
of  full-grown  continents.  Yet  the  lakes  of  greatest  geological  interest 
are  not  those  of  the  present  era,  but  of  that  next  preceding.  Those  of 
North  America  formed  over  the  emerging  land  of  the  Eocky  Mountain 
region  had  great  area,  and  received  abundant  debris  for  lacustrine  deposits 
from  a  newly  made  mountain  range. 

But  another  condition  existed;  for  the  great  lake-basins  were  subsiding 
areas,  so  that  the  deposits  continued  thickening,  as  the  subsidence  made 
progress,  until  5000  to  10,000  feet  of  beds  were  laid  down, — as  the  region 
of  modern  coral  reefs  is  described,  on  page  149,  as  subsiding  while  the  reefs 
thickened. 

These  Tertiary  lacustrine  formations  prove  their  fresh-water  origin  by 
containing  remains  of  abundant  fresh-water  and  terrestrial  life,  from  Quad- 
rupeds or  Mammals,  of  many  more  kinds  than  now  exist  in  North  America, 
to  Snakes  and  Turtles,  Fishes,  and  Insects  and  even  Butterflies,  besides  leaves 
and  other  relics  of  the  forest. 


AS    A    MECHANICAL   AGENT.  203 


SPECIAL  POINTS  IN  FLUVIAL  HISTORY. 

The  history  of  rivers  has  been  eventful.  In  the  course  of  the  geological 
past,  drainage  areas  have  sometimes  changed  to  areas  of  marshes,  lakes,  or 
ocean;  and  again  back  to  dry  land,  with  perhaps  new  limits  and  slopes.  They 
have  experienced  changes  of  level  that  divided  and  subdivided  them,  or 
forced  part  of  a  stream  in  a  new  direction  for  an  outlet ;  that  annexed  another 
stream,  giving  it  a  new  head,  and  doubling  its  length,  supply  of  waters, 
and  mean  pitch,  —  as  in  the  case  of  the  Mississippi,  which  once  had  the 
Saskatchewan  as  its  source.  They  have  had  portions  buried  under  debris,  and 
have  been  compelled  to  make  long  -circuits,  and  deep  cuts,  in  order  to  effect  a 
new  connection ;  or  have  been  buried  with  all  their  fluvial  deposits  beneath 
floods  of  lavas,  —  as  on  the  west  slope  of  the  Sierra  Nevada  (Whitney),  —  and 
so  have  made  fossil  river-channels,  some  of  them  to  remain  buried,  others  to 
regain  their  places  wherever  the  surface  conditions  favored  it.  They  have 
had  their  slopes  increased  by  continental  elevation,  so  that  after  reaching  a 
state  of  feebleness,  they  acquired  new  energy  and  were  set  again  to  work  at 
the  deepening  of  their  channels  and  the  enlarging  of  their  valleys ;  or  they 
have  suffered  from  subsidences  that  have  slackened  the  flow  over  the  subsided 
region  and  brought  on  premature  old  age,  or  spread  a  stream  into  a  lazy 
lake ;  or  by  the  coming  on  of  a  period  of  enormous  precipitation,  and  of 
glaciers  ending  in  glacial  floods,  they  have  once  more  been  made  young  and 
powerful  in  denudation  and  transportation  over  the  width  of  a  continent. 

•  Furthermore,  streams  that  originated  over  a  formation  covering  a  country, 
and  derived  their  courses  from  its  slopes  and  lines  of  weakness,  have  some- 
times been  forced  by  the  removal,  through  denudation,  of  that  formation,  to 
chisel  down  their  channels  into  older  underlying  beds,  and  fix  upon  the  latter, 
as  far  as  possible,  their  original  qualities.  An  example  of  a  drainage  area 
with  such  inherited  qualities  was  described,  in  1874,  by  A.  R.  Marvine  (Hay- 
den's  Report  of  1873),  from  the  slopes  east  of  the  Front  Range  of  Colorado. 
The  deposition  of  Triassic  and  other  strata  over  the  region  was  followed  by 
its  emergence,  and  the  outlining  of  a  system  of  drainage  down  the  long  slopes 
of  the  rising  continent.  But  since  then  the  new  streams  in  their  upper 
portion  have  cut  through  these  strata  to  the  older  rocks ;  and  here  the  work 
of  impressing  the  courses  of  the  new  canons  on  these  older  rocks  is  going 
on,  mostly  irrespective  of  their  slopes  and  structure-lines.  Twelve  years 
earlier,  J.  Beete  Jukes,  of  the  Irish  Geological  Survey,  treating  of  the  mode 
of  formation  of  some  river- valleys  in  the  south  of  Ireland  (Q.  J.  G.  S.,  1872), 
brought  out  the  same  general  idea  that  the  drainage  courses  of  the  present 
time  have  often  been  determined  by  preexisting  topography. 

A  course  of  drainage  derived  from  a  formation  that  once  covered  the 
region  is  called  by  Powell  superimposed  drainage.  Further,  if  the  course  of 
a  river  is  a  consequence  of  the  structure  of  an  upturned  region,  he  terms  it 
consequent  drainage ;  but  if  derived  from  conditions  prior  to  the  upturning, 
antecedent.  (Exploration  Colorado  River,  1875.)  • 


204  DYNAMICAL   GEOLOGY. 

Buried  river  valleys.  —  Rivers  of  the  Sierra  Nevada,  in  Tuolumne  County, 
California,  that  had  their  channels  buried  beneath  lavas  in  the  later  Tertiary, 
afterward,  in  a  comparatively  short  time,  cut  new  channels  through  the 
thick  lava  stream  and  the  underlying  rocks  to  depths  1500  to  2000  feet 
below  the  old  channels.  (Whitney,  1865,  1879.)  They  hence  are  strong 
evidence  of  increased  precipitation,  as  held  by  Whitney,  and  also,  according 
to  LeConte  (1879,  1886),  of  increased  elevation  in  the  mountains;  and  both 
conditions  characterized  the  Glacial  period  which  was  in  progress  during 
part  or  nearly  all  of  the  cutting.  Like  evidence  of  elevation  exists  also  in 
the  river  channels  of  southern  California  beyond  the  limits  of  the  lava-flood, 
as  observed  by  LeConte  (1886),  who  thence  concludes  that  the  elevation 
extended  along  the  whole  length  of  the  Sierras. 

The  ultimate  result  of  denudation  over  a  continent  is,  as  usually  stated, 
the  transfer  of  the  mountains  to  the  sea,  bringing  all  to  a  nearly  level  plain. 
But  the  facts  from  Tahiti,  explained  on  page  182,  appear  to  show  that  the 
process  would,  as  a  general  thing,  first  thin  down  the  mountains  to  sharp 
peaks  and  ridges;  and  after  this,  the  continuation  of  the  thinning  would 
ultimate  in  a  general  level  —  given  time  sufficient.  The  Adirondacks  have 
stood  ever  since  Archaean  time,  with  the  height  probably  never  less  than 
5000  feet ;  and  yet  they  are  to  a  large  extent  in  the  Tahitian  stage.  But  the 
streams  of  extensive  drainage  areas  become  to  a  greater  or  less  extent  base- 
leveled;  and  through  the  continued  leveling  work  along  them,  with  that  of 
the  minor  tributaries,  a  wide  region  may  be  finally  reduced  approximately 
to  a  plain.  Such  a  plain  has  been  termed  by  W.  M.  Davis  a  peneplane,  from 
the  Latin  for  almost  and  plain;  for  it  may  still  have  ledges  of  the  harder 
rocks  and  other  irregularities  of  surface.  An  elevation  of  the  land,  and 
other  causes  indicated  above,  may  expose  such  regions  to  a  new  base- 
leveling. 

The  fluvial  history  of  a  country,  it  thus  appears,  may  have  great  com- 
plexity, and  require  a  large  amount  of  study  and  an  experienced  judgment 
for  its  correct  elucidation. 

SUBTERRANEAN  WATERS. 

Water  descends  from  the  surface  by  gravity,  filling  all  open  subterranean 
spaces,  and  also  the  pores  of  the  solid  rocks.  Its  lower  limit  is  determined 
by  the  earth's  interior  heat ;  and  the  lower  limit  of  outward  discharge,  by  a 
level  not  much  below  that  of  the  ocean's  surface.  At  greater  depths,  conse- 
quently, subterranean  water  may  be  that  of  early  ages  in  geological  history, 
and  in  part  the  sea  water  in  which  the  deposits  were  made,  more  or  less 
modified  in  its  saline  contents  and  their  amount  by  long  contact  with  the 
various  rocks.  Not  only  the  waters  of  the  rains  and  rivers  thus  take  a 
downward  way  through  the  porous  rocks,  between  their  sloping  layers  and 
along  all  crevices,  but  also  those  of  lakes,  which  are  sources  of  permanent 
supply,  and  pre-eminently  those  of  the  ocean. 


WATER   AS   A   MECHANICAL   AGENT.  205 

The  more  solid  crystalline  rocks  imbibe  less  than  0-2  per  cent  of  water, 
and  hold  it  so  strongly  by  capillary  attraction  that  when  once  filled  there  is 
little  further  change,  if  they  are  below  the  influence  of  surface  droughts,  and 
away  from  that  of  subterranean  heat.  But  some  sandstones  are  so  porous 
that  they  give  easy  passage  to  the  waters  from  above  ;  and  unaltered  strati- 
fied rocks  generally  have  much  open  space  between  the  layers. 

The  amount  of  water  contained  in  different  rocks  taken  near  or  at  the  surface  has 
been  found  to  be  as  follows  :  porphyry,  0-012  per  cent  of  the  rock-mass  ;  a  feldspathic 
granite,  0-0203  (Durocher,  1853);  coarse  granite,  0-37  per  cent ;  euryte,  0-07  ;  milky  quartz 
from  a  vein,  0-08  ;  flint  from  the  Upper  Chalk,  at  Meudon,  0-12  ;  but  sandstone  (Gres  de 
Fontainebleau,  near  Meudon),  2-73;  a  Tertiary  limestone  (Calcaire  grossier),  3-11 
(Delesse,  1861).  The  Calcaire  grossier  will  absorb  18-03  per  cent  of  water ;  a  quartzose 
Tertiary  sandstone,  29-00 ;  the  chalk  near  Issy,  24-10 ;  a  Silurian  slate,  near  Angers,  0-19 ; 
granite,  0-12  (Delesse,  1861).  Chalk  will  absorb  2  gallons  of  water  per  cubic  foot  (Prest- 
wich);  the  Old  Red  Sandstone  (Devonian)  of  Gloucestershire  absorbs  11-60  per  cent; 
limestone  of  the  Lower  Oolyte,  12-15 ;  Carboniferous  limestone  of  Clifton,  England, 
0-70  (Wethered,  1882). 

The  amount  of  moisture  absorbed,  after  drying  at  a  temperature  between  150°  F. 
and  200°  F.,is  as  follows:  for  Potsdam  sandstone,  3  specimens,  2-26  to  2-71  per  cent;  3 
others,  6-94-9-35  ;  for  Trenton  limestone,  0--32  to  1  -70,  the  former  for  a  black  variety  ;  for 
some  dolomytes,  10-0  to  13-55 ;  a  crystallized  dolomyte,  of  the  Calciferous  formation,  4  speci- 
mens, 1-89  to  2-53 ;  2  other  specimens,  5-90  to  7-22 ;  for  the  Medina  argillaceous  sand- 
stone, 2  specimens,  8-37  to  10-06  (T.  S.  Hunt,  1865). 

A  square  bar  of  Triassic  building-stone  from  Runcorn,  England,  1-92  inches  square  and 
14-92  high,  being  half  immersed  in  a  can  of  water,  the  water  rose  to  the  top  by  capillarity 
in  2V  hours,  taking  in  4  ounces  of  water;  and  the  same  stone  made  in  the  form  of  a 
siphon,  emptied  a  can  of  its  water.  The  pore  space  was  nearly  ^  of  the  stone.  (M. 
Reade,  1884.) 

1.  Flow  of  underground  waters.  —  In  regions  of  massive  or  schistose 
crystalline  rocks  of  close  texture,  there  is  no  proper  flow  unless  there  are 
vertical  fissures ;  and  then  the  water  will  descend  to  the  bottom  of  the  fis- 
sures, and  there  remain,  or  push  off  laterally  if  the  space  admits  of  it.  But  if 
the  rocks  are  uncrystalline  stratified  kinds,  the  water  flows  downward  along 
the  surface  of  the  less  pervious  layer,  and  soaks  more  or  less  through  the 
others.  Subterranean  waters  often  come  out  on  the  faces  of  bluffs,  and  indi- 
cate the  position  of  the  more  impervious  layers  by  a  belt  of  foliage  above, 
kept  green  by  the  exuding  moisture ;  or  they  form  springs  or  streamlets  at  the 
base  of  bluffs  ;  or  they  feed  pools  or  lakes  ;  or  make  springs  off  shores  below 
tide  level.  In  regions  of  loose  sand-beds  and  gravel-beds  they  generally  find, 
at  a  depth  of  a  few  yards  or  scores  of  yards,  a  hard  layer  —  hardened  by 
deposits  of  iron  oxide  or  otherwise  (called  in  popular  language  hard-pan}, 
which  carries  along  the  accumulating  waters,  and  becomes  a  source  of  supply 
to  the  numerous  wells  of  a  village  or  city ;  and  the  same  hard  layer,  if 
sloping  seaward,  will  afford  water  by  boring,  even  out  in  a  bay. 

In  the  deep  sand  deposits  of  the  southern  side  of  Long  Island,  where  the  seaward 
slope  of  the  surface  for  the  6  miles  to  low- tide  level  is  1 : 265  feet,  there  is  a  water -plane 


206  DYNAMICAL  GEOLOGY. 

below,  which  slopes  1 : 425  feet,  or  12  \  feet  per  mile.  The  discharge  of  water  at  sea  level  is 
so  large,  although  dependent  solely  on  the  rains,  that  the  city  of  Brooklyn,  containing 
nearly  a  million  inhabitants,  has  derived  from  it  its  supply  of  water  through  a  series 
of  reservoirs,  constructed  a  little  above  the  sea  level.  The  water-plane  is  not  that  of  a 
hard-pan  layer.  Its  position  has  been  determined  by  well-digging.  Out  of  the  42| 
inches  of  rain  (snow  included)  which  annually  falls,  nearly  40  per  cent  becomes  ab- 
sorbed and  subterranean.  The  Brooklyn  engineer,  Mr.  T.  Weston,  observes  that  these 
subterranean  waters  supply  the  small  streams  of  the  surface  with  the  chief  part  of  their 
water,  and  discharge  a  large  amount  into  the  sea ;  and  after  a  careful  survey  of  a  part 
of  this  southern  slope,  east  of  Brooklyn,  73-64  square  miles  in  area,  he  reported  that  the 
water  supply  from  the  surface  streams  was,  on  an  average,  22  per  cent  of  the  precipita- 
tion, or  30,000,000  gallons  a  day ;  that  15  per  cent  additional  came  out  along  the  shores 
of  the  bays  ;  and  that  at  least  40,000,000  gallons  per  day  might  be  obtained  in  reservoirs  by 
proper  arrangements.  Mr.  Weston  holds  that  the  water- plane  is  the  upper  limit  of  a  water 
region  which  extends  from  this  plane  downward  to  and  below  the  sea  level,  and  that  there 
is  no  hard-pan  layer  underneath.  Friction  and  capillarity  in  the  sands  give  it  its  height. 

A  coral  island  but  ten  feet  high  and  a  few  hundred  yards  wide,  and 
consisting  of  coral  rock  up  to  the  water  level  with  coral  sands  above, 
generally  yields,  on  digging  down  to  the  surface  of  the  coral  rock,  a 
sufficient  supply  of  water  for  its  inhabitants,  and  all  of  it  has  come  from 
the  rains.  The  fresh  water,  moreover,  is  sufficient  to  exclude,  by  its  sea- 
ward pressure,  all  ingress  of  salt  water.  If  this  is  true  on  a  coral  island, 
the  subterranean  waters  derived  from  the  rains  over  larger  lands  should 
be  very  great.  Moreover,  the  salt  waters  of  the  ocean  do  not  penetrate 
far  into  the  basement  of  a  continent.  An  island  may  receive  sea  water  to 
its  center  at  some  unascertained  depth  below  the  sea  level;  but  not  so 
a  continent. 

2.  Force  of  flow.  —  The  force  of  the  flow  of  subterranean  waters  is  due 
to  gravity,  like  the  flow  of  surface  waters.  There  is  everywhere  hydrostatic 
pressure,  varying  directly  with  the  height  of  the  supply,  minus  the  loss  by 
friction  and  capillarity.  The  height  may  be  that  of  the  neighboring  hills, 
or  of  distant  mountains,  according  to  the  range  of  the  sloping  rock-layers 
along  which  the  water  descends.  It  may  be  that  of  lakes  small  or  large,  for 
these  bodies  of  water  have  the  double  duty  of  supplying  above-ground  and 
under-ground  streams.  While  the  hydrostatic  pressure  varies  with  the  height 
of  the  water-supply,  the  extent  of  the  region  served  by  a  single  source  will 
depend  on  the  area  of  that  source. 

Professor  Edward  Orton,  of  Columbus,  Ohio,  has  proved  that  the  hydro- 
static pressure  in  the  Findlay  oil-region,  and  also  in  Indiana,  where  the  bor- 
ings descend  to  the  Trenton  limestone,  reaching  it  at  various  depths  to  1000 
feet  or  more  below  the  surface,  is  determined  by  the  waters  of  Lake  Superior. 
The  level  of  the  lake  is  600  feet  above  tide  level;  and  by  adding  this  height 
to  the  number  of  feet  at  which  the  Trenton  lies,  in  any  case,  below  tide  level, 
and  calculating  the  hydrostatic  pressure  on  this  basis,  he  has  found  that  it  cor- 
responds closely  with  the  actual  gas  pressure  at  each  boring.  He  holds  that 
this  hydrostatic  pressure  determines  the  gas  pressure  in  other  regions ;  and 


WATER   AS   A  MECHANICAL  AGENT. 


207 


187. 


hence  that  the  pressure  is  rarely,  if  ever,  due,  as  has  been  supposed,  to  the 
pressure  of  confined  gas.  The  facts  exhibit  on  a  grand  scale  the  influence  of 
a  large  elevated  lake  on  the  conditions  of  subterranean  pressure. 

Wherever  subterranean  water  flows  between  nearly  impervious  sloping 
layers,  so  that  it  is  confined  to  a  given  channel,  it  is  like  the  water  in  a  long 
inclined  tube  ;  and  on  opening  a  hole  through  the  overlying  material  it  will 
rise  in  a  jet,  owing  to  the  hydrostatic  pressure.  The  height  of  the  jet  so 
produced  is  that  of  the  source,  diminished  by  the  loss  from  friction  and  the 
resistance  of  the  air  ;  it  may  be  hundreds  of  feet. 

In  the  annexed  cut  (Fig.  187),  ab  represents  a  water-supporting  layer; 
6c,  the  boring ;  and  cd,  the  jet  of  water.  Such  wells  are  called  Artesian 
wells,  as  they  were  first  made  in  the  district  of  Artois,  in  France.  They 
are  now  an  important  means  of  securing  water  for  irrigation  and  other 
purposes  in  various  parts  of  the  world.  By  this  means  abundant  water  is 
now  obtained  even  on  the  seacoast  region  of  New  Jersey,  from  Cretaceous 
and  Tertiary  strata,  and  over  various  parts  of  the  dry  regions  of  Montana, 
Colorado,  and  Nevada,  where  arid  sands  have  been  covered  thereby  with 
foliage.  But  if  the  rocks  are  porous 
throughout,  with  no  impervious  layers, 
boring  is  of  no  avail.  Borings  in  regions 
of  metamorphic  or  crystalline  rocks  gen- 
erally prove  failures  unless  a  chance  bed 
of  decomposed  rock  extending  down  from 
the  surface  should  be  reached ;  for  such 
rocks  have  been  consolidated  and  crystal- 
lized while  under  heavy  pressure.  Where 
slates  are  vertical,  a  horizontal  boring 
across  the  bedding  may  give  a  constant 
stream ;  but  such  a  source  is  a  small  one. 

3.  Denudation ;  Transportation.  —  Subterranean  rivers  have  sometimes 
large  size,  especially  in  limestone  regions,  where  excavation  is  easy,  as  ex- 
plained on  page  130,  under  Chemical  Geology.  Those  of  the  caverns  of 
Kentucky  and  Indiana  have  their  cascades,  like  ordinary  rivers,  and  may 
be  navigated  for  long  distances.  Into  such  caverns  rivers  sometimes 
enter  and  become  "lost  rivers;"  while  from  others  issue  great  streams, 
whose  source  is  unknown.  The  cave  of  Adelsberg,  22  miles  northeast  of 
Trieste,  has  its  river ;  and  the  Jura  Mountains  send  forth  streams  to  day- 
light full  grown.  The  work  of  denudation  and  transportation  is  like 
that  above  ground,  although  less  supplied  with  materials  for  transporta- 
tion and  wear. 

Subterranean  waters  do  much  efficient  work  in  a  quiet  way  by  the  trans- 
portation of  sand  along  the  course  of  streamlets  that  have  their  outlet  at 
the  base  of  bluffs.  The  undermining  of  centuries  in  this  way  may  make 
chambers  that  lead  to  the  sinking  of  masses  of  the  land,  and  determine 
lines  of  surface  drainage. 


Section   illustrating   the   origin   of   Artesian 
wella. 


208  DYNAMICAL   GEOLOGY. 

4.  Landslides.  —  Subterranean  waters  sometimes  produce  disastrous  re- 
sults by  adding  their  weight  to  loose  or  porous  deposits  and  so  occasioning 
landslides. 

Landslides  are  of  three  kinds  :  — 

(a)  The  mass  of  earth  on  a  side-hill,  having  over  its  surface,  it  may  be,  a 
growth  of  forest  trees,  and,  below,  beds  of  gravel  and  stones,  may  become  so 
weighted  with  the  waters  of  a  heavy  rain,  and  so  loosened  below  by  the 
same  means,  as  to  slide  down  the  slope  by  gravity. 

A  slide  of  this  kind  occurred,  during  a  dark,  stormy  night,  in  August,  1826,  in  the 
White  Mountains,  back  of  the  Willey  House.  It  carried  rocks,  earth,  and  trees  from  the 
heights  to  the  valley,  and  left  a  deluge  of  stones  over  the  country.  The  frightened 
Willey  family  fled  from  the  house,  to  their  destruction.  The  house  remains,  as  on  an 
island  in  the  rocky  stream. 

(&)  A  clayey  layer,  overlaid  by  other  horizontal  strata,  sometimes  becomes 
so  softened  by  water  from  springs  or  rains,  that  the  superincumbent  mass, 
by  its  weight  alone,  presses  it  out  laterally,  provided  its  escape  is  possible, 
and,  sinking  down,  takes  its  place. 

Near  Tivoli,  on  the  Hudson  River,  a  subsidence  of  this  kind  took  place  in  April, 
1862.  The  land  sunk  down  perpendicularly,  leaving  a  straight  wall  around  the  sunken 
area,  60  or  80  feet  in  height.  An  equal  area  of  clay  was  forced  out  laterally  underneath 
the  shore  of  the  river,  forming  a  point  about  an  eighth  of  a  mile  in  circuit,  projecting  into 
the  cove.  Part  of  the  surface  remained  as  level  as  before,  with  the  trees  all  standing. 
Three  days  afterward,  the  slide  extended,  partially  breaking  up  the  surface  of  the  region 
which  had  previously  subsided,  and  making  it  appear  as  if  an  earthquake  had  passed. 
The  whole  area  measured  3  or  4  acres. 

(c)  When  the  rocks  are  tilted,  and  form  the  slope  of  a  mountain,  the 
softening  of  a  clayey  or  other  layer  underneath,  in  the  manner  just  explained, 
may  lead  to  a  slide  of  the  superincumbent  beds  down  the  declivity. 

In  1806,  a  destructive  slide  of  this  kind  took  place  on  the  Rossberg,  near  Goldau,  in 
Switzerland,  which  covered  a  region  several  square  miles  in  area  with  masses  of  con- 
glomerate, and  overwhelmed  a  number  of  villages.  The  thick  outer  stratum  of  the  moun- 
tain moved  bodily  downward,  and  finally  broke  up  and  covered  the  country  with  ruins, 
while  other  portions  were  buried  in  the  half-liquid  clay  which  had  underlaid  it  and  was 
the  cause  of  the  catastrophe. 

Similar  subsidences  of  soil  have  taken  place  near  Nice,  on  the  Mediterranean.  On 
one  occasion,  the  village  of  Roccabruna,  with  its  castle,  sunk,  or  rather  slid  down,  with- 
out destroying  or  even  disturbing  the  buildings  upon  the  surface. 

Besides  (a)  the  transfer  of  rocks  and  earth,  landslides  also  cause  (b) 
a  scratching  or  planing  of  slopes,  by  the  moving  strata  and  stones ;  (c)  the 
burial  of  animal  and  vegetable  life;  (d)  the  folding  or  crumpling  of  the 
clayey  layer  subjected  to  the  pressure,  where  the  effect  does  not  go  so  far 
as  to  produce  its  extrusion  and  destruction ;  while  the  beds  between  which 
it  lies  are  only  slightly  compacted  or  are  unaltered;  and  (e)  depressions 
of  the  surface  which  may  become  lake-basins.  Fig.  188  is  a  reduced  view  of 


WATEK   AS   A   MECHANICAL   AGENT.  209 

a  layer  thus  plicated,  from  the  Quaternary  of  Booneville,  N.Y.  Vanuxem 
illustrates  the  facts  there  observed  by  him,  with  this  and  other  figures 
(N.  Y.  Geological  Report),  and  attributes  the  plications  to  lateral  pressure 
while  the  layer  was  in  a  softer  state  than  those  contiguous. 

In  parts  of  the  shores  of  western  Patagonia,  18g 

where  the  soil  is  always  wet,  the  soil-cap  is 

always  slipping  downward  over  the  basement 
rock ;  and  it  carries  along  not  only  its  cover- 
ing of  trees  and  shrubbery,  but  also  a  "moraine 
profonde"  of  rocks,  stones,  tree-trunks,  peat 
and  mud,  denuding  the  hills,  filling  valleys,  and 
feeding  the  ocean.  (R.  W.  Coppinger,  1881.) 
Areas  on  the  Falklands,  called  "  stone  rivers," 

,  . ,  .    .  ._TT    ri_.  Plicated  clayey  layer.     Vanuxem. 

may  nave  the  same  origin.     (W.  Thomson.) 

Soil-cap  movements  and  land-slips  sometimes  dam  up  valleys  and  make 
lakes.  But  loading  with  waters  is  only  one  of  the  methods  of  producing 
such  movements. 

Amount  of  absorbed  water  within  the  earth.  —  The  amount  of  absorbed 
water  in  the  earth  has  been  increasing  from  the  time  of  the  earth's  consoli- 
dation. The  thickening  of  the  supercrust,  by  the  addition  of  sedimentary 
strata,  has  been  attended  by  a  continued  addition  to  the  amount.  Ejected 
igneous  rocks  take  in  water  on  cooling.  Other  sources  of  augmentation  are 
the  making  of  hydrous  iron  oxides  through  oxidation,  of  clays  through  the 
decomposition  of  feldspar,  and  of  gypsum  and  other  hydrous  minerals. 

If  the  thickness  of  the  supercrust  over  the  continental  portion  of  the 
globe  average  10  miles,  and  the  average  volume  of  moisture  in  the  forma- 
tions, both  metamorphic  and  unaltered,  be  2-5  per  cent,  the  whole  amount 
of  water  absorbed  and  confined  would  be  -fa  of  10  miles,  or  about  1300 
feet  in  depth,  for  the  area  of  the  continents.  The  deposits  over  the  oceanic 
basins  have  relatively  little  thickness.  Whatever  reasonable  allowance  be 
made  for  them,  the  whole  loss  to  the  ocean  waters,  in  depth,  from  this 
source,  will  not  exceed  800  feet.  The  confined  water  of  the  rocks,  while  a 
feeble  agent  of  change  at  the  ordinary  temperature,  is  one  of  immense 
importance  when  much  heat  is  present. 

II.  THE  OCEAN  AS  A  MECHANICAL  AGENT. 

The  working  agencies  of  the  ocean  of  a  mechanical  kind  are,  as  has  been 
stated,  those  of  (1)  the  tidal  wave ;  (2)  the  wind-made  waves  and  currents ; 
and  (3)  earthquake  waves.  Besides  these  agencies,  the  sun's  heat,  by  vary- 
ing the  temperature  and  density  of  the  water,  affects  the  ocean's  movements. 

In  mechanical  work,  the  waters  of  the  ocean  have  an  advantage  over 

fresh  waters  in  being  of  greater  specific  gravity  by  -fa  to  -fa.     They  have 

also  the   important  quality  of  depositing  sediment  more  rapidly,  because 

less  viscous,  owing  to  the  saline  condition  of  the  waters.     A  fine  sediment, 

DANA'S  MANUAL — 14 


210  DYNAMICAL   GEOLOGY. 

which  takes  10  to  14  days  to  settle  in  pure  water,  settles  in  14  to  18  hours 
in  a  solution  of  common  salt  (W.  H.  Sidell,  1838).  A  fine  clayey  precipitate 
goes  down  in  a  solution  of  the  strength  of  sea  water  in  30  minutes,  which  in 
pure  water  would  take  as  many  days  (W.  H.  Brewer,  1883). 

Since  the  chief  part  of  oceanic  work  requires  the  presence  of  rock-mate- 
rial, depth  of  water  is  a  condition  of  prime  importance.  It  is  only  within 
shallow  depths  that  the  waters  come  extensively  into  working  contact  with 
rocks ;  only  in  the  shallow  belt  where  water  and  rocks  are  together  along  the 
emerging  line  that  the  greatest  amount  of  force  is  generated  for  work.  Being 
at  a  depth  of  500  feet  in  the  ocean  is  not  as  complete  removal  from  oceanic 
forces  as  being  500  feet  above  it,  but  the  geological  results  produced  at  this 
and  greater  depths  are  relatively  small.  As  explained  beyond,  there  are 
wide  differences  between  the  work  of  the  upper  10  fathoms  along  shores,  and 
that  of  the  depths  from  10  to  100  fathoms ;  of  greater  depths  along  the  sides 
of  the  oceanic  basin  when  reached  by  marine  currents ;  and  of  depths  from 
100  fathoms  to  abyssal  depths,  remote  essentially  from  all  currents. 

It  is  therefore  obvious  that  the  era  in  geological  history  when  the  ocean 
carried  on  the  greatest  amount  of  rock-making  was  that  of  general  con- 
tinental submergence  at  shallow  depths,  with  a  scattering  of  emerged  rocky 
ridges  or  areas.  This  was  the  condition  of  the  earth  through  the  Paleozoic 
eras ;  and,  to  a  large  extent,  through  Mesozoic  time.  The  condition  was  in 
striking  contrast  with  the  later  and  present  state,  in  which  the  continents 
have  only  a  narrow  margin  of  shallow  water.  This  fact  should  be  kept  in 
mind  when  comparing  ancient  geological  events  with  modern.  The  time  of 
the  greatest  amount  of  ocean  work  was  that  of  the  least  amount  of  river 
work. 

CHARACTERISTICS  OF  THE  WORKING  AGENCIES. 

1.   The  Tidal  Wave. 

The  tidal  wave  moves  as  a  force  wave,  and  has  a  mean  height,  along 
coasts  where  least  influenced  by  the  land,  of  less  than  a  foot.  The  height  on 
the  projecting  capes  of  continents  is  1  to  2  feet,  but  along  intervening 
coasts  commonly  from  4  to  12  feet,  and  in  bays  and  straits,  15  to  18  feet 
or  more.  Along  the  east  coast  of  North  America,  southern  Florida,  Cape 
Hatteras,  and  Nantucket  are  the  dividing  points  between  a  "  Southern," 
"Middle,"  and  "Eastern"  Bay  (Bache).  The  height  is  1  to  1£  feet  at 
southern  Florida,  2  at  Cape  Hatteras,  and  1  at  southeastern  Nantucket ; 
but  in  the  Southern  Bay  at  Savannah  it  is  7  feet ;  in  the  Middle  Bay,  at 
New  York,  it  is  5  feet ;  in  the  Eastern,  at  Boston,  10  feet. 

Up  deep  bays,  when  the  tide  enters  between  strongly  converging  coast 
lines,  the  wave  increases  much  in  height.  At  the  Bay  of  Fundy,  an  unusu- 
ally long  wave  enters  and  reaches  a  height  of  40  feet,  and  even  60  to  70  feet 
at  the  highest  tides ;  the  advancing  wave  is  like  a  moving  water-fall .  of 
majestic  extent,  but  without  foam.  At  the  entrance  to  the  Bristol  Channel, 


WATER   AS   A   MECHANICAL   AGENT. 


211 


England,  the  maximum  height  is  18  feet,  and  within  it,  at  the  mouth  of 
the  Severn,  45  to  50  feet.  In  Long  Island  Sound  (Fig.  189),  which  is 
about  100  miles  long,  the  tide  outside,  at  Block  Island,  is  but  2  feet ;  but 
inside,  at  New  London,  it  is  3  feet ;  at  the  mouth  of  the  Connecticut,  4 ; 
at  New  Haven,  6;  at  Bridgeport,  7;  and  off  Hewlett's  Point,  near  Hell 
Gate,  where  it  meets  the  inflowing  tide  of  New  York  Bay,  7-|-  feet.  The 
map  shows  further,  by  the  cotidal  lines  over  the  Sound,  that  the  time  of 
the  passage  from  Block  Island  to  Hewlett's  Point  is  about  4J-  hours ;  and 
that,  at  the  fourth  hour,  it  is  high  tide  almost  simultaneously  along  the 
whole  inside  coast.  The  height  of  the  tide  is  depressed  somewhat  by 
high  atmospheric  pressure,  but  the  amount  of  depression  is  not  yet  pre- 
cisely ascertained. 

189. 


Long  Island  Sound,  | 
Long  Island, 

and  the 
Atlantic  Border 

with 

Depths  along  Bathymetric 
ines  in  fathoms ;  Cotidal 
inea  m  Long  Inland  Sound; 
the  under-water  Channel 
of  Hudson  River, 
Coast  Survey  Charts 


73JOO 


When  the  tide  enters  straits  by  two  passages,  progress  in  either  direction 
depends  on  depth  and  obstructions,  and  leads  to  meeting  at  different  heights. 
At  Batscham,  in  Tong-king,  the  waves,  coming  from  the  China  and  India  seas, 
meet  bringing  opposite  but  nearly  equal  changes  in  the  water  level,  and  the 
result  is  almost  no  perceptible  tide.  The  tidal  wave  of  New  York  Bay  meets 
that  of  the  Sound  at  varying  heights,  causing  violent  currents  at  Hell  Gate ; 


212  DYNAMICAL   GEOLOGY. 

and  at  each  ebb,  on  an  average,  448,000,000  cubic  feet  pass  from  the  Sound 
westward. 

Again,  where  the  tide  up  a  large  river  is  detained  at  the  head  of  a  gradu- 
ally contracting  estuary  by  sand-bars  with  only  narrow  passages,  it  some- 
times moves  up  the  river  all  at  once  in  one  or  a  few  great  waves,  producing 
what  is  called  an  eager  (or  bore) ;  as  at  the  mouth  of  the  Hoogly  (one  of  the 
mouths  of  the  Ganges),  on  the  Tsien-Tang  in  China,  and  on  the  Amazon.  In 
the  Tsien-Tang,  at  the  equinoxes,  the  wave  moves  as  a  foaming  wall  of  water, 
20  feet  or  more  high  and  four  or  five  miles  broad,  and  thus  it  passes  Hang- 
Chau-Fu  at  a  rate  of  25  miles  an  hour,  dying  out  about  80  miles  above.  The 
change  from  ebb  to  flood  tide  is  almost  instantaneous.  (Macgowan,  1855.) 

At  the  large  northern  mouth  of  the  Amazon,  the  pororoca,  as  it  is  there 
called,  passes  up  the  stream  in  three  or  four  closely  following  waves,  each 
15  to  20  feet  high.  As  soon  as  the  previous  tide  stops  running  out,  the 
approaching  wave  is  seen  as  a  white  line  on  the  eastern  horizon ;  onward  it 
comes  with  rumbling  sounds  (imitated  in  the  word  pororoca)  that  grow 
louder  and  louder ;  finally  it  rushes  forward  over  the  top  of  the  long  wall, 
like  an  endless  cataract,  in  quick  pursuit  by  the  other  waves ;  and  continues 
up  the  river  for  70  or  80  miles,  or  two  thirds  of  the  way  to  Macapa.  (J.  C. 
Branner,  1884.) 

Rivers  with  open  mouths  receive  the  tidal  wave  quietly  and  carry  it  as  far 
within  as  high-tide  level  goes,  the  movement  being  communicated  to  the 
water  of  the  river,  and  the  salt  water  following  for  part  of  the  distance,  and 
ending  as  an  under-current.  It  extends  up  the  Amazon  to  Obidos,  nearly 
500  miles ;  up  the  Hudson  to  Troy,  150  miles,  two  waves  being  in  the  river 
.at  once;  up  the  Connecticut  to  Hartford,  50  miles.  Rising  above  the  level 
of  the  wells  along  the  coast  and  the  outlets  of  subterranean  streams,  it  raises 
their  waters,  so  that  such  wells  also  have  their  tides. 

In  seas  more  or  less  shut  in  from  the  ocean  and  outside  of  the  general 
course  of  the  tidal  wave,  the  tides  are  small.  In  the  Mediterranean,  for 
example,  the  tide  is  perceived  only  at  the  ends  of  bays,  as  at  Venice  in  the 
Adriatic. 

In  consequence  of  the  tidal  movement  the  sea  has  its  flood-grounds,  like 
rivers ;  but  the  floods  occur  twice  a  day,  with  each  recurring  tide. 

At  some  places  in  the  Pacific,  owing  to  the  conjunction  of  tidal  waves,  high  water 
occurs  uniformly  at  12  h.,  and  low  at  6  h.  This  is  the  case  at  Tahiti,  where  the  tide  has  a 
height  of  1  to  \\  feet.  The  author  governed  himself  accordingly  in  his  excursions  at  low 
water  over  the  coral  reefs. 

2.   Winds :    Wind-made  Waves  and  Currents. 

As  the  great  currents  of  the  oceans  —  the  Atlantic  and  others  —  are 
attributed  by  many  to  the  action  of  the  regular  winds,  these  currents  may 
here  come  under  consideration  as  well  as  those  made  by  storm-winds.  But 
the  currents  made  by  the  storm-winds,  that  is,  the  littoral  currents  and  the 


WATER   AS   A   MECHANICAL  AGENT.  213 

attendant  waves,  are  the  efficient  agents,  because  they  act  directly  against 
and  along  the  coasts,  and  have  great  power. 

Storm-winds,  as  stated  on  page  159,  have  often  a  velocity  of  60  to  10() 
miles  an  hour.  They  have  built  up,  by  drift-sands  alone,  the  east  side  of  the 
Bermuda  reefs  to  a  height  exceeding  200  feet,  while  the  regular  winds  have 
not  raised  the  side  of  the  coral  reef  facing  them  above  high-tide  level.  They 
have  made  similar  drift-hills  on  the  Bahamas,  and  over  the  Florida  reefs. 

Waves  rise  in  long  lines  transverse  to  the  course  of  the  winds,  but  with 
irregularities  in  the  lines,  owing  to  veerings  and  other  variables  in  the  driv- 
ing agent.  Their  height  depends  on  the  size  of  the  sea,  as  well  as  on  the 
winds,  and  in  shallow  water  on  its  depth.  But  every  seventh  or  eighth  wave 
is  often  a  maximum,  it  being  a  combination  of  two,  one  overtaking  another. 

Waves  have  at  times  great  height.  The  highest  measured  by  Scoresby 
stood  43  feet  above  the  intervening  trough,  or  21J  feet  above  the  mean 
water-plane  or  plane  of  rest.  According  to  results  obtained  by  the  United 
States  Hydrographical  Department,  the  storm-waves  of  the  North  Atlantic 
have  a  maximum  height  of  44  to  48  feet,  but  ordinarily  a  height  of  30  feet, 
and  a  length  of  500  to  600  feet. 

But  the  depth  of  the  action  of  waves  is  moderate.  In  a  wave,  each  par- 
ticle of  water  moves  in  a  circle  about  its  center  of  rest,  —  a  circle  of  21J 
feet  radius  in  a  wave  of  43  feet.  But  these  circles  at  a  depth  of  only  one 
wave-length  have  a  radius  3-^  of  that  at  the  surface,  and  at  a  depth  of  two 
wave-lengths,  3  0  ^  0  0  ;  so  that  if,  for  the  43-foot  waves,  the  wave-length  — 
or  the  distance  between  the  crest  of  two  consecutive  waves  —  is  300  feet, 
the  circle  at  a  depth  of  one  wave-length  will  have  a  diameter  of  ^  of  an 
inch,  and  at  two  wave-lengths,  y^j-  of  an  inch.  Consequently  the  move- 
ment of  the  heaviest  waves  in  the  open  ocean  is  exceedingly  slight,  if  appar- 
ent at  all,  at  a  depth  of  100  fathoms.  This  depth  is  the  probable  limit  of 
the  movement  of  sand  by  wave-action,  but  not  the  limit  of  the  action  of 
currents. 

3.   Earthquake  Waves. 

In  an  earthquake,  the  movement  of  the  earth  may  be  either  (1)  a  simple 
vibration  of  a  part  of  the  earth's  crust,  or  (2)  a  vibration  with  actual  eleva- 
tion or  subsidence.  If  submarine  waves  are  produced,  they  have  a  forward 
impulse,  and,  in  the  second  case,  an  actual  forward  movement  or  amplitude 
equivalent  to  the  amount  of  change  of  level ;  in  each  case,  therefore,  they 
are  translation  waves.  The  velocity  of  propagation  varies  as  the  square  root 
of  the  depth,  the  number  of  miles  per  hour  being  12*2  miles  in  a  depth  of  10 
feet;  38-7  in  that  of  100  feet;  122-3  in  that  of  1000.  An  earthquake  at 
Concepcion,  Chile,  set  in  motion  a  wave  that  traversed  the  ocean  to  the 
Society  and  Navigator  Islands,  3000  and  4000  miles  distant,  and  to  the 
Hawaiian  Islands,  6000  miles ;  and  on  Hawaii  it  swept  up  the  coast,  tem- 
porarily deluging  the  village  of  Hilo.  An  earthquake  at  Arica,  and  other 
parts  of  southern  Peru,  August  14, 1868,  sent  a  wave  across  the  Pacific,  west- 


214  DYNAMICAL   GEOLOGY. 

ward  to  New  Zealand  and  Australia,  northwestward  to  the  Hawaiian  Islands, 
northward  to  the  coast  of  Oregon ;  and  this  was  repeated  in  May,  1877. 

4.   The  Sun's  Heat:    a  Cause  of  Varying  Temperature  and  Density. 

Evaporation  causes  an  increase  in  the  proportion  of  salt  in  the  ocean,  or 
in  its  salinity,  and  thereby  an  increase  *in  density ;  and  this  is  under  cer- 
tain conditions  a  potent  cause  of  currents.  The  Mediterranean  Sea  affords 
an  example.  It  has  been  estimated  that  this  sea  loses  annually  60  per  cent 
of  its  water  by  evaporation,  and  receives,  through  rivers  and  precipitation, 
about  30  per  cent ;  so  that  there  is  a  deficit  of  30  per  cent  which  is  supplied 
by  the  Atlantic  through  the  straits  of  Gibraltar.  It  is  consequently  inferred 
that  if  the  connection  with  the  ocean  were  cut  off,  the  sea  would  be  reduced 
to  a  great  basin  with  two  intensely  salt  "Dead  Seas,"  an  eastern  and  a 
western.  (It  has  been  suggested  that  this  may  have  been  its  condition  dur- 
ing or  since  the  Glacial  period.)  In  consequence  of  this  loss  by  evapora- 
tion, the  water  is  -^  more  saline  than  that  of  the  Atlantic  (page  49).  On 
account  of  this  condition  the  sea  has  an  inward  and  outward  current  at  Gib- 
raltar ;  the  latter  carrying  off  the  denser  Mediterranean  waters ;  the  former 
resupplying  the  loss  resulting  from  both  evaporation  and  the  outflow.  It 
has  been  calculated  that  the  inflowing  current  is  equivalent  to  a  current 
eight  miles  wide,  600  feet  deep,  moving  at  the  rate  of  18*3  miles  in  24 
hours.  The  currents  being  reversed  with  the  tides,  this  is  the  balance 
of  the  inflow  over  the  outflow  in  the  upper  current.  (Carpenter,  1872; 
Buchanan,  1883.)  On  the  varying  salinity  of  sea  water,  see  page  121. 

MECHANICAL  EFFECTS. 

1.    Tidal  Wave  and  Currents. 

1.  The  tidal  inflow.  —  Since  the  tidal  wave  becomes  a  translation  wave  on 
soundings,  it  thereby  gains  theoretically  some  power  of  transportation.  But 
on  open  coasts  the  inflowing  movement  at  the  rate  of  a  few  feet  only  in  six 
hours  is  too  slow  for  much  efficient  work.  Its  feebleness  as  a  geological  agent 
can  be  best  appreciated  during  a  calm  day  on  the  seashore  when,  although 
the  air  and  waters  are  seemingly  at  rest,  the  tide  is  nevertheless  rising. 

The  tidal  wave  in  its  landward  movement  follows  the  deeper  parts  of  the 
bays  and  sounds,  where  friction  is  least,  and  with  less  velocity  their  coasts. 
It  is  therefore  weak  in  sea-border  work.  This  is  well  shown  by  the  cotidal 
lines  of  Long  Island  Sound  on  the  preceding  map  as  laid  down  by  Schott. 
These  lines  reach  the  coast  of  the  Sound  along  its  western  half  nearly  at  the 
same  time.  The  tide  enters  the  Sound  along  its  bottom,  as  an  "  underrun," 
one  and  a  half  hours  before  the  ebb  of  the  surface  waters  has  ceased  (E. 
E.  Haskell). 

The  rising  tide  affords  the  wind-made  waves  a  chance  twice  a  day  to  ply 
their  blows  against  cliffs  and  beaches  at  regularly  changing  heights,  and  thus 


WATER   AS   A   MECHANICAL  AGENT.  215 

promotes  abrasion  on  sea-borders  in  a  way  not  possible  on  the  shores  of 
lakes.  The  flow  up  the  coast  and  the  tidal  rivers  sets  back  the  river  waters, 
gives  them  increased  depth,  and  floods  the  tidal  flats. 

Passing  up  large  bays  which  gradually  narrow  inward,  the  mass  of  water 
becomes  forced  to  quicker  movement  or  greater  height,  or  both,  to  keep  time 
with  the  advance  behind ;  and  in  such  cases,  coasts,  against  which  there  is 
friction,  may  be  worn,  and  if  shallow,  some  stirring  up  of  the  bottom  may  be 
produced.  And  if,  further,  the  waters  are  held  back  by  obstructing  banks 
until  nearly  at  full  tide  before  they  move  in,  they  may  rush  forward,  as  in 
the  eager,  with  greater  destruction.  When  the  eager  of  the  Tsien-Tang  is 
approaching  Hang-Chau-Fu,  the  boats  along  the  shore  are  quickly  rowed  to 
the  middle  of  the  stream  and  placed  with  the  bow  to  the  wave ;  they  rise 
and  fall  as  it  passes,  —  about  20  feet,  —  and  in  a  few  minutes  are  back  at 
their  shore  traffic,  —  facts  evincing  that  the  waters  are  those  of  a  wave,  and 
not  of  a  current.  But  along  shores  that  obstruct  the  movement  artificial 
embankments  or  dykes  are  often  torn  up. 

The  eager  or  pororoca  of  the  Amazon  has  the  action  of  an  enormous 
plunging  wave.  The  forest-covered  land,  as  Branner  states,  is  torn  up  to 
great  depths ;  forests  are  uprooted  and  swept  away,  the  trees  left  matted 
and  tangled  and  twisted  together  upon  the  shore,  or  half  buried  in  the  sands, 
"  as  if  they  had  been  so  many  strings  or  bits  of  paper,"  and  the  region  inland 
over  which  the  flood  has  swept  is  loaded  with  the  debris.  Moreover,  new 
islands  of  large  size  and  new  shoals  and  bars  and  channels  are  left  behind  it. 
Branner  adds  that  this  is  the  work  of  the  tidal  wave,  not  of  a  tidal  current. 

2.  The  outflow.  — By  the  inflow  of  the  tidal  wave  a  great  body  of  water 
along  a  coast  is  raised  some  feet  above  low-tide  level,  and  acquires  thereby 
an  amount  of  energy  depending  on  the  height  of  the  tide.  The  energy  is 
expended  during  the  outflow  in  abrasion,  transportation,  deposition,  overcom- 
ing friction,  and  in  other  ways ;  and  sometimes  it  is  utilized  for  impounding 
a  portion  of  the  water  at  high  tide,  and  making  it  turn  a  water-wheel  for  a 
mill  or  a  pump.  As  has  been  remarked,  it  may  become  an  important  source 
of  heat  to  man  when  coal-beds  are  burnt  out. 

It  is  the  source  of  tidal  currents.  The  ebbing  waters  lie  on  the  bottom  of 
shallow  bays  and  necessarily  follow  the  lowest  channels ;  and  they  thus  be- 
come divided  into  many  workers,  which  may  severally  abrade  or  scour  the 
bottom,  though  generally  more  or  less  combined  in  their  work  of  transporta- 
tion and  deposition.  Along  the  deeper  middle  portion  of  Long  Island  Sound 
the  mean  velocity  of  the  outflow  is  2-8  feet  per  second,  and  of  the  inflow  3-2 
feet  (Haskell). 

The  force  of  the  outflowing  waters  through  bays  is  augmented  where 
rivers  add  to  the  depth,  and  also  by  the  additions  to  the  waters  of  a  bay  by 
storm-winds. 

The  denuding  or  scouring  action  of  the  movement,  added  to  that  of  the 
inflow,  is  manifest  not  only  at  harbor  entrances,  but  also  over  the  sea-bottom 
in  its  shallower  parts.  In  Long  Island  Sound  wherever  there  is  any  narrow- 


216  DYNAMICAL   GEOLOGY. 

ing  by  shoals  or  islands  there  is  an  increase  of  the  depth  and  velocity,  and 
consequently  an  increased  denuding  force.  South  of  Norwalk  (long.  73°  23' 
W.),  where  the  breadth  is  reduced  one  half  by  a  projecting  point  of  Long 
Island,  the  depth  at  center  is  increased  from  15  to  32  fathoms.  Again,  south 
of  Stratford  (long.  73°  6'),  there  is  a  shoal,  and  consequently  a  deepening  to 
27i  fathoms.  Again,  to  the  eastward,  south  of  the  mouth  of  the  Connecticut 
Biver,  where  the  Sound  is  narrowing  toward  its  obstructed  entrance,  the 
depth  increases  in  5  miles  from  12-15  fathoms  to  25-29  fathoms ;  and  then, 
in  40  miles,  nearing  the  entrance,  to  45,50,  and  55  fathoms.  The  accessions 
of  waters  from  the  rivers  give  some  aid  in  this  deepening.  Once  outside,  the 
depth  of  the  waters  diminishes  ;  but  the  channel  made  by  the  scour  may  be 
traced  until  Block  Island  is  passed ;  and  the  loops  just  south,  of  30,  40,  50 
fathoms  in  the  bathymetric  lines,  suggest  that  it  may  extend  in  a  wider  form 
nearly  to  the  100-fathom  line.  However  this  may  be,  the  sea-bottom  channel 
indicated  on  the  map  southeastward  of  New  York  Bay,  while  rightly  con- 
sidered the  former  course  of  the  Hudson  River  channel  during  a  period  of 
sea-border  emergence  (D.,  1857),  probably  owes  its  present  depth  out  to  the 
40-fathom  line,  to  the  combined  effects  of  drifted  sands  and  the  scouring 
action  of  the  ebbing  waters  (D.,  1890).  « 

In  the  discharge  of  a  river  into  a  salt-water  bay,  the  fresh  waters  flow 
over  the  salt ;  and  in  some  cases  so  little  commingling  takes  place  that 
shallow  streams,  carrying  little  detritus,  leave  uninjured  the  marine  life  of 
the  bottom. 

3.  Deposition  usually  takes  place  inside  of  bays  or  estuaries  wherever  there 
is  an  eddying  of  the  waters  or  diminished  velocity,  as  well  as  over  tidal  flats. 
There  is  deposition  also  at  the  entrance  of  the  bay,  when  the  tidal  waters 
meet  the  sea  outside,  and  spread  and  rapidly  lose  velocity :  and  at  the  ebb, 
this  area  of  deposition  may  become  prolonged  into  and  up  the  bay.  But 
part  of  the  inside  deposits  are  scoured  away  with  the  next  outflow. 

Deposition  off  shore  of  the  detritus  made  by  the  grinding  of  beach  sands 
is  only,  to  a  very  small  degree,  a  result  of  tidal  action.  It  is  chiefly  wave 
and  current  work.  The  making  of  ripples  over  sand-flats  and  shallow  sea- 
bottoms  is  partly  a  result  of  the  gentle  tidal  inflow  or  outflow ;  but  it  is  also 
the  work  of  wave-and-current  movements. 

The  height  of  the  tide  fixes  an  upper  limit  to  tidal  flats  and  sand-bars  in 
estuaries  and  bays  by  the  limit  it  gives  to  deposition.  But  the  seashore  flats 
along  some  rocky  shores  are  a  result  simply  of  the  shearing  action  of  the 
passing  waves. 

2.    Wind-made  Waves  and  Currents. 

1.  Their  power.  — The  waves  that  come  in  from  the  ocean  and  break  heavily 
on  the  beaches  and  against  the  cliffs,  are  wind-made  waves ;  and  those  of 
great  force  are  made  and  propelled  by  storm-winds.  Their  progress  is  land- 
ward ;  and  the  break  at  summit  takes  place  when  the  depth  of  water  below 
the  trough  equals  about  one  half  the  height  of  the  wave.  The  wave  ad- 


WATER   AS  A  MECHANICAL  AGENT.  217 

vances,  and  rises  in  consequence  of  the  diminishing  depth.  At  the  break- 
ing, or  the  collapse,  of  the  wave,  the  waters  are  thrown  forward,  and  dash, 
for  the  most  part,  up  the  shore,  while  the  trough  part  of  the  wave  flows  off 
as  the  "  undertow,'7  followed  down  the  beach  by  the  returning  water  of  the 
collapsed  wave. 

Some  features  of  the  movement  are  well  illustrated  in  Hawaiian  surf-riding.  The 
Hawaiian,  swimming  out  with  his  plank,  plunges  beneath  the  first  billow  and  rises  beyond 
it ;  then  dives  beneath  another,  and  another,  until  he  has  passed  one  of  the  great  billows. 
This  he  mounts,  and,  if  rightly  placed  on  it,  rides  to  the  beach  with  great  speed.  Should 
his  plank  not  keep  the  right  angle  on  the  crest  of  the  billow,  the  surf  of  the  following  wave 
will  overtake  him  ;  but  this  he  would  avoid  by  diving  beneath  it  and  swimming  out  farther 
for  a  fresh  start. 

The  work  done  by  the  wave-and-current  agency  includes  abrasion  of  the 
most  violent  kind,  as  well  as  the  gentlest,  and  transportation  and  deposition 
as  extensive  as  coast  lines  and  shallow  sea-borders  or  seas.  It  is  the  agency 
that  preserves  to  the  continents  the  detritus  of  the  discharging  rivers,  inas- 
much as  waves  work  landward ;  yet  it  has  aid  in  this  in  the  fact  that  sedi- 
ment drops  in  salt  water  in  one  fifteenth  of  the  time  required  in  fresh.  On 
the  borders  of  the  Gulf  of  Mexico,  according  to  A.  Agassiz,  river  sediments 
do  not  extend  out  beyond  the  100-fathom  line,  for  at  this  depth  there  is 
always  the  usual  sea-bottom  life.  Along  the  Atlantic  border  there  are  sedi- 
ments in  deeper  water,  but  this  is  because  icebergs  or  icefloes  have  dropped 
there  loads  of  gravel  and  sand.  This  agency  also  makes  impossible  the 
transportation  of  material  from  one  continental  land  to  another.  If  the 
fabled  Atlantis  were  at  the  surface  over  the  Dolphin  shoal  (page  19), 
the  waves  and  currents  would  work  about  it  and  for  it,  and  allow  of  no 
contributions  to  any  outside  land,  and  least  of  all  to  America  —  the  con- 
tinent supposed  to  have  needed  help. 

2.  Work  of  denudation.  —  The  waves  bring  to  bear  the  violence  of  a  cataract 
upon  whatever  is  within  their  reach,  —  a  cataract  that  girts  all  the  continents 
and  oceanic  islands.  In  stormy  seas,  they  have  the  force  of  a  Niagara,  but 
with  far  greater  effects ;  for  Niagara  falls  into  a  watery  abyss,  while,  in  the 
case  of  the  waves,  the  rocks  are  made  bare  anew  for  each  successive  plunge. 
They  work  by  impact,  and  with  enormous  force.  They  have  also  great 
abrading  power  added  to  impact,  through  the  load  of  debris  they  take  up 
and  transport.  Stevenson,  in  his  experiments  at  Skerryvore  (west  of  Scot- 
land), found  the  average  force  of  the  waves  for  the  five  summer  months 
to  be  611  pounds  per  square  foot,  and  for  the  six  winter  months,  2086  pounds. 
He  mentions  that  the  Bell  Rock  Lighthouse,  112  feet  high,  is  sometimes 
buried  in  spray  from  ground-swells  when  there  is  no  wind,  and  that  on  No- 
vember 20,  1827,  the  spray  was  thrown  to  a  height  of  117  feet,  —  equivalent 
to  a  pressure  of  nearly  three  tons  per  square  foot.  During  a  westerly  gale  in 
March,  1845,  his  dynamometer  registered  a  pressure  of  6083  pounds  per  square 

foot,  which  gives  for  the  velocity  per  second,  by  the  formula,      *.  (P  being 


/6083 


218  DYNAMICAL   GEOLOGY. 

the  pressure  in  pounds  and  64  the  weight  of  a  cubic  foot  of  sea  water), 

x  32'2  =  55-32  feet.     The  hydrostatic  pressure  due  to  a  wave  20  feet 
64 

high  is  over  (1280  Ibs.)  half  a  ton  to  the  square  foot;  the  rest  of  the  force 
comes  from  its  velocity.  Mr.  Stevenson  states  that  on  one  of  the  Hebrides  a 
mass  of  rock  of  about  42  tons  weight  was  gradually  moved  in  a  storm  five 
feet ;  with  each  incoming  wave  it  was  made  to  lean  landward,  and  the  back 
run  uplifted  it  with  a  jerk,  leaving  it  with  little  water  about  it. 

It  is  reported  that  at  Unst,  one  of  the  Shetlands,  walls  were  overthrown 
and  a  door  broken  open  at  a  height  of  196  feet  above  sea  level.  Geikie  attrib- 
utes part  of  the  effects  of  the  impact  to  the  compression  of  the  air  of  cavities 
by  the  striking  waters,  and  then  its  sudden  expansion,  with  tearing  effects ; 
and  also  to  the  rarefaction  of  air  caused  by  the  sudden  withdrawal  of  the 
waters  after  a  broad  stroke,  this  leading  to  displacement  of  blocks  or  masses. 
He  mentions  the  case  of  a  securely  fastened  door  at  the  Eddystone  Light- 
house forced  outward  by  the  stroke  of  the  outside  surface  by  a  wave ;  and 
suggests  that  the  principle  may  account  for  stones  being  started  from  their 
places  in  a  solidly  built  stone  wall.  The  water  driven  into  crevices  has  great 
rending  force. 

The  heaviest  waves  exert  little  force  against  rocky  cliffs,  or  the  sea-bot- 
tom, below  a  depth  of  15  or  20  feet.  Their  abrading  action  cannot,  therefore, 
shear  off  cliffs,  or  wear  away  an  island  in  the  ocean,  to  a  lower  level.  This 
principle  is  recognized  in  making  defense  walls  of  masonry  against  breakers 
by  planting  the  wall  out  where  the  depth  is  15  to  20  feet. 

Waves,  as  they  march  up  a  shore,  sometimes  throw  stones  to  great  heights. 
Geikie  cites  the  report  that  during  northwesterly  gales  the  windows  of  the 
Dunnet  Head  Lighthouse,  at  the  northern  extremity  of  Scotland,  300  feet 
above  high  water,  are  sometimes  broken  by  stones  from  the  enormous 
breakers. 

In  view  of  the  force  at  work  it  is  not  surprising  that,  in  regions  like  Cape 
Horn,  or  the  coast  of  Scotland,  where  storms  are  common,  cliffs  should  under- 
go constant  degradation,  be  fronted  by  lofty  castellated  and  needle-shaped 
rocks,  and  that  the  land  should  be  pierced  at  times  for  blow-holes  where 
layers  of  easy  removal,  or  dikes  or  veins,  face  the  breakers. 

The  following  figures  from  a  memoir  by  Professor  Shaler  illustrate  well 
some  of  the  results.  They  represent  scenes  on  the  coast  of  Maine,  near 
Mount  Desert. 

Fig.  190  shows  a  detached  rock  on  its  march  seaward;  and  Fig.  191 
a  pile  of  displaced  masses  as  it  was  left  at  the  base  of  a  cliff  before  an  ele- 
vation of  the  coast  of  220  feet.  All  the  processes  of  rock-destruction  help 
in  this  work  of  degradation, — the  opening  of  rifts  by  intruding  moisture,  or 
by  oxidation,  or  by  change  of  temperature,  or  by  growing  plants  and  the 
decay  of  weak  portions  of  the  rocks.  Under  the  incessant  beating,  every 
stroke  tends  to  slip  out  of  place  masses,  however  large,  that  rest  on  a  sur- 
face not  perfectly  horizontal. 


WATER    AS    A   MECHANICAL   AGENT. 


219 


The  cliffs  of  Norfolk  and  Suffolk,  England,  afford  an  example  of  seashore 
encroachment  that  has  long  been  under  observation  as  the  country  is  one 
of  houses  and  cultivated  fields.  Lyell  states  that  in  1805,  when  an  inn  at 
Sherringham  was  built,  it  was  50  yards  from  the  sea,  and  it  was  computed 
that  it  would  require  70  years  for  the  sea  to  reach  the  spot  —  the  mean 
loss  of  land  having  been  calculated,  from  former  experience,  to  be  somewhat 
less  than  one  yard  annually.  But  it  was  not  considered  that  the  slope  of 
the  ground  was  from  the  sea.  Between  the  years  1824  and  1829,  17  yards 
were  swept  away,  bringing  the  waters  to  the  foot  of  the  garden ;  and  in  1829 


190. 


Rock  detached  by  wave-action,  Otter  Creek,  Mount  Desert,  Me.     Shaler,  '* 


there  was  depth  enough  for  a  frigate,  20  feet,  at  a  spot  where  a  cliff  of  50 
feet  stood  48  years  before.  Farther  to  the  south,  the  ancient  villages  of 
Shipden,  Wimp  well,  and  Eccles  have  disappeared.  This  encroachment  of 
the  sea  has  been  going  on  from  time  immemorial. 

3.  Limit  of  wave-denudation ;  Planation. — Besides  battering  and  degrad- 


220 


DYNAMICAL   GEOLOGY. 


ing  cliffs,  wave-action  makes  shore-platforms,  by  shearing  away  the  rocks  of 
coasts  down  to  a  horizontal  surface  near  low-tide  level,  and  in  the  process 
cliffs  are  undermined  and  set  back.  These  effects  are  produced  where  the 
rocks  are  of  moderate  firmness, — where  they  are  not  too  hard  to  yield  rather 
easily  to  the  waves,  and  not  so  weak  as  to  be  torn  up  by  the  gentler  attack 
of  low-tide  movements.  As  the  tide  rises,  the  earlier  waters  quietly  cover 


191. 


Rocks  detached  by  wave-action,  Mount  Desert,  on  an  old  beach  at  a  height  above  the  sea  of  220  feet. 

Shaler,  '89. 

the  rocks.  Then  the  waves  move  in ;  but  the  rocks  below  are  under  protec- 
tion, and  only  those  of  the  cliff  or  wall  take  the  force  of  the  blow.  There 
is  hence,  in  such  cases,  a  level  of  no  wear  near  low-tide  level.  The  level  of 
greatest  wear  is  that  of  the  stroke  of  the  breaker  at  or  above  high  tide. 


WATER    AS    A   MECHANICAL   AGENT. 


221 


This  feature  of  wave-action,  and  the  reality  of  a  level  of  little  or  no 
wear  above  low  tide,  are  well  illustrated  by  facts  observed  by  the  author 
in  1840  on  the  coasts  of 

Australia  and  New  Zealand.  ^2* 

In  Fig.  192  (representing 
the  south  cape  at  the  en- 
trance to  the  harbor  of  Port 
Jackson,  New  South  Wales), 
the  horizontal  strata  mak- 
ing the  base  of  the  cliff,  cut 
crosswise  by  joints,  extend 
out  in  a  platform  a  hundred 
yards  wide.  The  tide  rises 
and  covers  the  platform  ;  and 
the  waves,  unable  to  reach 


Cliffs  at  entrance  to  Port  Jackson,  New  South  Wales, 
Australia.    D.,  Note-book,  '40. 


its   rocks  to  tear  them  up, 

because    of    the    protection 

thus   afforded,   drive   on   to 

batter  the  lower  part  of  the  cliff.     The  strata  belong  to  the  Sydney  sandstone 

formation.  At  the  Bay  of  Islands,  New  Zealand,  there  is  a  similar  seashore 

platform,  as  illustrated  in  Fig.  193,  represent- 
193.  ing  an  island  in  the  bay  called  "  The  Old  Hat." 

The  rock  here  is  a  rather  firm  argillaceous 
sandstone  without  bedding.  By  elevation  such 
shore-platforms  become  sea-border  terraces. 

«  The  Old  Hat,"  New  Zealand.  D.  '40.  Another  region  of  such  shore-platforms  is  the  Island 

of  Anticosti  in  the  Gulf  of  St.  Lawrence.     They  have 

a  width  there  of  100  to  150  yards  (Verrill).  The  broad  seashore  platform  of  coral  islands 
or  atolls  has  the  same  origin  (page  146).  It  occurs  on  both  their  leeward  and  windward 
sides,  and  varies  little  in  surface  from  horizontally.  Coral-made  limestone,  like  other 
kinds,  is  of  easy  abrasion. 

As  here  shown,  there  is  a  limit  to  wave-abrasion.  Under  the  circum- 
stances stated,  it  does  not  cut  much  below  low-tide  level  Even  an  atoll  stands 
its  ground  and  grows  in  size  in  spite  of  the  waves  of  a  Pacific.  Much  less 
can  wave  action  cut  valleys  into  the  land.  Its  province  is  to  batter  down 
cliffs,  wear  off  headlands,  and  fill  up  bays. 

The  largest  blocks  that  are  raised  and  carried  up  seashore  are  those  that 
are  forced  along  by  earthquake  ivaves.  These  waves  commence  their  tearing 
work  at  depths  that  at  other  times  are  under  the  protection  of  the  waters, 
and  the  waters,  which  had  retreated  from  the  shore  to  make  the  waves, 
advance  to  an  unwonted  height,  and  make  deposits  of  what  they  have  gath- 
ered at  varying  distances  inland,  according  to  their  gravity,  besides  devastat- 
ing the  country  they  cover.  But  the  depth  of  their  action  probably  does 
not  exceed  30  feet.  A  ship  afloat  is  -easily  moved  landward,  more  easily 


222  DYNAMICAL   GEOLOGY. 

than  blocks  of  rock  are  torn  from  submerged  strata.  The  earthquake  of 
1746,  on  the  coast  of  Peru,  carried  a  frigate  several  miles  inland,  besides 
deluging  the  seaport  Callao,  and  the  city  of  Lima  seven  miles  distant.  The 
following  figures  represent  masses  of  coral  limestone  torn  off  from  the 
margin  of  an  atoll  and  thrown  on  the  shore-platform.  That  of  Fig.  194,  was 
10  x  6  x  6  feet  in  its  dimensions,  and  that  of  Fig.  195  seven  feet  high  and  six 

104.  195. 


Blocks  on  the  shore-platform  of  atolls  in  the  Paumotu  Archipelago.    D.  '49. 

broad.  The  latter  is  attached  solidly  to  the  reef-rock,  and  is  half  cut  through 
by  wave  action.  Another  mass  on  the  shore-platform  had  a  length  of  15  feet. 

4.  Transportation  and  deposition;  the  making  of  beaches.  —  Waves,  as  they 
rise  on  a  shelving  coast,  take  up  and  bear  along  detritus  of  all  degrees  of 
coarseness  according  to  the  velocity,  and  throw  or  wash  it  up  the  shore. 
Grinding  work  or  corrosion  is  also  ever  going  on.  By  such  means  they  give 
the  beach  its  material,  and  through  the  return  of  the  waters,  by  which  much 
of  the  finer  debris  is  restored  to  the  sea,  its  angle  of  slope. 

The  materials  are  derived  from  the  wear  of  cliffs  and  ledges  above 
the  beach;  from  the  loose  material  of  the  bottom;  from  any  corals  and 
shells  and  other  organic  objects  living  in  the  waters ;  and  from  the  contribu- 
tions of  marine  currents  as  well  as  those  of  rivers  —  whatever  is  at  hand 
being  used.  The  transported  materials  may  be  gathered  from  depths  of  30 
feet  or  more.  In  regions  of  high  tides  and  stormy  seas,  the  great,  rapidly 
driven  waves,  as  they  move  up  the  coast,  may  pick  up  large  stones  or  produce 
them  out  of  the  rocks,  and  make  stony  beaches,  or  they  may  make  a  place 
too  rough  for  a  beach.  But  with  lower  tides,  and  away  from  the  rocks, 
the  beaches  consist  mostly  of  sand  and  gravel.  Nine  tenths  of  all  the 
beaches  between  Florida  and  Cape  Cod  are  sand-made. 

The  slope  of  the  beaches  varies  much  in  angle.  It  is  15°  to  18°  along  the 
coasts  of  stormy  seas  and  high  tides,  7°  to  10°  along  those  of  low  tides,  and 
3°  and  less  in  sheltered  bays.  Deposition  by  the  return-flow  waters  gives 
this  part  of  the  beach  a  straticulate  structure  parallel  to  the  inclined  surface 
(page  93). 

Since  the  waves  go  up  and  down  the  beach  twice  in  each  24  hours,  and 
gradually  become  stronger  in  flow  and  plunge  as  the  tide  rises,  the  beach  is 
made  to  consist  of :  (1)  The  summit  ground,  of  uneven  surface.  This  is  the 
receiving  place  for  the  coarser  material,  including  stones,  shells,  etc.,  and  also 


WATER   AS    A   MECHANICAL  AGENT.  223 

for  long  lines  of  seaweeds,  which  the  wash  of  the  waters  carries  up  the  beach 
and  has  to  leave  because  the  sands  of  the  upper  and  drier  part  take  most  of 
the  waters  off  by  absorption.  Here  and  just  below  are  often  found  accumu- 
lations of  magnetic  iron  sand  and  garnet  sand,  which  the  return-flow  was  not 
strong  enough  to  carry  back  down  the  beach  with  the  other  lighter  sands. 
(See  page  170.)  (2)  The  beach-slope,  the  outer  surface  of  the  beach-formation, 
the  stratification  being  parallel  to  it.  When  sand-made,  its  surface  is  marked 
with  faint  channelings  of  rills  from  the  return-flow,  and  more  faintly  with 
wave-like  outlines  of  the  upward  wash.  (3)  The  under-wetter  slope  —  the 
continuation  of  the  beach-slope  downward  beneath  the  water  made  by  the 
undertow  and  perhaps  coarser  in  material  than  the  part  above.  It  is  the 
place  for  boring  Mollusks,  Sea-worms,  and  Crustaceans.  Stones  and  coarse 
shells  that  may  be  dropped  by  the  flinging  breakers  on  the  beach-slope  are 
pretty  sure  to  be  carried  back  by  the  return-flow  for  another  chance  of  trans- 
port, because  the  plane  of  rest  is  underneath  them  and  not  through  their 
centers  of  gravity ;  and  for  the  same  reason  the  stones  of  experimenters  on 
beach-action  usually  go  the  unexpected  way  —  seaward. 

The  grinding  carried  on  over  the  beach  reduces  the  sand  to  finer  sand, 
and  especially  the  grains  of  feldspar  and  of  all  minerals  softer  than  quartz. 
The  undertow  carries  these  seaward,  where  the  current  distributes  them  over 
the  shallow  bottom.  In  this  way  deposits  of  fine  earth,  clay,  or  mud  are 
forming  near  those  of  coarse  sand  or  gravel.  Tidal  flats  of  mud  or  sand  in 
estuaries,  when  lying  exposed  above  low  water,  are  likely  to  receive  ripple- 
marks,  foot-prints  of  passing  animals,  raindrop  prints,  mud-cracks,  and  to 
secure,  when  the  tide  turns,  their  burial  beneath  other  sands  and  thus  their 
preservation.  Under  the  tearing  action  of  the  heavier  seas,  the  summit- 
ground  may  be  put  temporarily  into  the  beach-slope,  or  large  portions  of  a 
beach  may  be  torn  away  and  reconstructed;  and,  since  the  volume  of  the 
return-flow  would  be  at  the  same  time  augmented,  the  beach  may  become 
temporarily  steeper  and  coarser.  Along  most  windy  shores  it  requires  only 
one  of  the  extraordinary  storms  that  come  at  long  intervals  to  destroy  much 
of  the  work  of  a  century. 

5.  Extension  of  beaches  into  points  or  spits,  and  barriers.  —  A  beach  is,  in 
the  long  run,  essentially  permanent  in  form  and  structure,  unless  a  coast  is 
undergoing  change  in  level  or  in  other  respects.  But  in  regions  of  frequent 
storms,  the  storm-made  waves  and  currents  give  the  sands  a  set  or  drift 
to  leeward.  When,  in  this  way,  the  line  of  a  beach  reaches  in  its  leeward 
extension  a  shallow  bay,  the  drift  of  sands,  still  continuing,  will  build  out  a 
point  where  the  current  loses  velocity  against  the  stiller  water  of  the  bay ; 
or,  if  the  water  is  not  too  deep,  it  will  extend  a  barrier  of  beach-sand  across 
the  bay,  cutting  off  an  inner  shallow  portion  from  the  ocean,  leaving  only  a 
single  oblique  entrance,  which  the  tides  had  kept  open.  By  such  means  the 
south  side  of  Long  Island,  and  a  large  part  of  the  Atlantic  coast  south  of 
New  York,  has  been  supplied  with  its  beach-sand  barriers,  and  also,  inside  of 
the  barriers,  with  a  long  range  of  sounds. 


224 


DYNAMICAL  GEOLOGY. 


The  map,  page  211,  affords  illustrations  of  these  barriers.  Montauk  Point  has  its 
"beach,  and  also  its  bluffs  of  sand  and  coarse  gravel.  Westward,  the  beach  is  continued  on  in 
a  series  of  barriers,  outside  of  a  series  of  shallow  bays,  which  extend  all  the  way  to  Coney 
Island  and  New  York  Bay.  The  barrier  is  seldom  over  600  yards  in  width,  and  is  almost 
wholly  bare,  yet  has  stumps  at  places  on  the  inner  side.  Moreover,  the  westward  drift 
of  the  sands  has  shallowed  the  waters  south  of  the  western  part  of  Long  Island.  The 
zigzags  here  in  the  10- fathom  bathymetric  line  show  the  direction  of  the  wave-and-current 
movement. 

Part  of  the  drifted  sands  of  these  beaches  were  supplied  from  the  bluffs  to  the  east- 
ward, but  part  are  the  gatherings  of  the  waves  from  the  sea-bottom  below  the  beach  and 
barrier,  and  a  small  part  are  from  the  feeble  streams  of  southern  Long  Island. 

Along  the  New  Jersey  coast  and  farther  south  the  beaches  are  usually  half  a  mile  to 
a  mile  in  breadth,  and  many  have  an  inner  forest-covered  belt.  Sandy  Hook  —  5  miles 
in  length  —  owes  its  existence  to  the  drifting  of  the  sands,  and  an  accompanying  inside 

current,  continued  through  both  the  ebb  and  flow 

196.  of  the  tide,  as    long  since  explained  by  Bache. 

The  drift  of  the  Atlantic  coast  is  here  carried  to 
the  very  margin  of  the  deepest  ship  channel  out 
of  New  York  Bay.  The  hook-like  shape  of  the 
extremity  may  be  due  to  drift  in  the  Long  Island 
direction  where  that  of  the  New  Jersey  direction 
is  forced  to  stop. 

Fig.  196  is  a  map  of  the  coast-region 
either  side  of  Cape  Hatteras  (H).  Along 
the  coast  south  of  New  York  the  rivers 
carry  out  a  large  amount  of  detritus, 
which  is  widely  distributed,  but  the  coarser 
is  gathered  up  by  the  waves  to  make  the 
barriers.  The  position  of  the  cape  was 
probably  determined  by  a  cape  of  rocky 
ridges  which  is  now  submerged.  Off  the 
great  Middle  Bay  of  the  Atlantic  coast  the 
storm-winds  have  their  greatest  velocity 
when  blowing  from  the  eastward  —  as 
they  do  at  the  Bermudas ;  and  hence  the 
course  of  the  wave-and-current  movement 
is  toward  New  York  Bay,  both  along 
southern  Long  Island  westward  and  from 
Cape  Hatteras  northward.  South  of  Cape 
Hatteras  (H)  the  drifting  is,  for  a  similar 
reason,  southwestward. 


€oast-region  of  North  Carolina;  CK,  Curri- 
tuck  Inlet  (to  Currituck  Sound) ;  N,  New 
Inlet;  H,  Cape  Hatteras  ;  O,  Ocracock 
Inlet;  C,  Cove  Inlet;  L,  Cape  Lookout. 


Examples  of  remarkable  driftings  of  beach  materials  along  the  Atlantic  coast  are  on 
record.  A  vessel,  the  "  Sylph,"  was  wrecked  in  1814-1815  on  the  south  side  of  Long  Island, 
and  materials  from  the  wreck  were  drifted  westward  beyond  Fire  Island ;  and  7  years 
afterward  her  rudder  was  found  20  miles  west  of  where  she  was  lost.  In  another  case, 
coal  from  the  cargo  of  a  vessel  wrecked  on  the  south  side  of  Nantucket  was  carried 
eastward  and  then  northward,  and  the  keeper  of  the  lighthouse  of  the  north  cape,  called 
Great  Point,  supplied  himself  from  it  with  fuel  for  the  winter ;  and  brick  from  another 


WATER   AS  A   MECHANICAL  AGENT.  225 

vessel  pursued  the  same  course.  Again,  an  anchor  with  10  fathoms  of  chain  attached, 
from  a  brig  of  200  tons  wrecked  on  Cape  Cod  near  Truro,  was  drifted  a  mile  and  a  half  to 
the  north  in  three  weeks.  These  facts  are  from  papers  by  Lieutenant  C.  H.  Davis  (1849, 
1851).  Such  transportation  is  beyond  the  power  of  any  currents ;  it  is  the  work  of  the 
dashing,  lifting,  and  propelling  waves. 

In  the  following  example,  the  change  of  position  197. 

is  connected  with  a  change  in  the  seasons.  J.  D. 
Hague  states  that  at  Baker  Island  (of  coral),  in  the 
Pacific  (0°  15'  X.,  176°  22'  W.),  this  fact  is  well  ex- 
hibited. In  Fig.  197,  I,  I,  I  is  the  southwest  point  of 
the  island,  and  R,  R,  R,  the  outline  of  the  coral-reef 
platform,  mostly  a  little  above  low-tide  level ;  its 
width,  cd,  100  yards.  In  the  summer  season,  when 
the  wind  is  from  the  southeast,  the  beach  has  the 
outline  s,  s,  s ;  during  the  winter  months,  when  the 
wind  is  northeast,  the  material  is  transferred  around 
the  point,  and  has  the  position  w,  w,  to,  having  a 
width  at  ab  of  200  feet.  A  vessel  wrecked  in  sum- 
mer, and  stranded  at  V,  was  transferred  to  V  in  the  course  of  the  month  of  November. 
(J.  D.  Hague,  '62.) 

6.  Sand-bars  at  the  entrances  of  harbors  or  mouths  of  tidal  rivers.  —  The 
material  of  the  sand-bars  which  obstruct  the  entrances  of  harbors  has  two 
main  sources :  an  inner,  and  an  outer ;  the  former  fluvial,  the  latter  the  wave- 
and-current  driftings  of  the  coast,  which  contribute  so  largely  to  sand-barriers. 
The  positions  of  the  bars  depend  much  on  the  strength  of  the  river  current ; 
but  also  on  the  direction,  form,  and  supplies  of  the  wave-and-current  move- 
ment produced  by  the  storm-winds.  A  small  stream  is  often  blocked  entirely 
by  a  sand-bar  across  its  mouths,  so  that  the  waters  reach  the  ocean  only  by 
percolation  through  the  beach.  But  large  streams  make  distant  sand-reefs 
or  barriers  through  the  aid  of  the  outflow,  and  keep  open  channels  even 
in  the  face  of  the  ocean. 

The  depth  of  water  over  the  sand-bars  at  the  mouth  of  a  large  river 
or  bay  is,  in  great  part,  only  3  to  10  feet :  a  remarkable  fact,  considering  the 
opposing  forces  at  work — the  tidal  outflow  and  inflow,  and  the  plunge  of  the 
storm-made  waves  over  the  mobile  sands.  The  sands  lie  along  the  area  of 
rest  between  the  contesting  movements.  New  York  Bay  (map,  page  211) 
affords  an  example.  The  contributions  of  river  sediment  come  from  the 
Hudson  River  and  from  small  New  Jersey  rivers ;  and  the  Hudson  is  mod- 
erate in  its  supplies,  considering  its  length  and  size,  because  it  has  almost  no 
tributaries  for  60  miles,  and  small  ones  for  100  miles,  owing  to  the  westward 
dip  of  the  Catskill  strata  and  the  barrier  of  the  Palisades  in  the  southern 
part.  The  wave-and-current  supplies  come  from  the  direction  of  the  Long 
Island  and  the  New  Jersey  coasts ;  for  New  York  Bay  is  exceptional  in 
lying  to  the  leeward  of  both  coasts.  Under  these  circumstances,  Sandy 
Hook,  the  sand-bars,  and  the  barriers  of  the  Long  Island  coast  adjoining, 
have  been  accumulated.  The  outlining  of  the  bars,  and  the  positions  of  the 
three  channels  through  them,  are  mainly  due  to  the  tidal  outflow,  which 
DANA'S  MANUAL,  — 15 


226 


DYNAMICAL   GEOLOGY. 


includes,  besides  the  tidal  waters  of  the  bay  and  river,  the  river  waters 
of  the  Hudson  and  of  the  New  Jersey  streams,  with  the  important  addition 
of  the  high-tide  overflow  from  Long  Island  Sound ;  and  the  southern  channel 
into  the  bay  is  the  deepest,  apparently  because  the  New  Jersey  streams 
empty  into  the  lower  bay  nearly  abreast  of  this  entrance.  Large  tidal 
grounds  about  a  harbor  are  more  essential  even  than  a  great  river  for  the 
best  conditions  of  harbor  entrances ;  and  any  encroachment  on  the  limits  in 
New  York  Bay  is  carefully  guarded  against.  The  depth  over  the  surface  of 
the  bars  is  mostly  between  3  and  10  feet. 


198. 


199. 


'    ^'^M-'^H^v  J/^/l 
^-x^?*  s  (Qc$\  $&<** 


10         16    C'4o 

so 3U  *°          15M 

'        25      2121  21  21.2422       g°       »X 
^42    "     31        ?I"^         ^    "    "H 


/* 

1    '//IS13  L.12     8    } 

i  y/fcw»v^ 


^7t-?^;S7V\iB™ 


Mouth  of  Connecticut. 


Harbor  of  New  Haven. 


Over  the  bars  at  the  mouth  of  the  Columbia  Kiver,  Oregon,  occurs  the 
same  small  depth.  A  vessel  ran  aground  on  the  outer  bar  on  July  18,  1841, 
and,  after  passing  a  night  of  calm  weather,  but  of  heavy  and  disastrous  toss- 
ings  as  the  waves  of  the  Pacific  rolled  in  during  the  progress  of  the  rising 
tide,  lay  quiet  at  daybreak  when  the  tide  was  out,  fixed  in  the  sands,  with  a 
belt  of  dry  sand  around  her.  The  next  day,  she  was  an  abandoned  wreck. 
(D.,  Notebook,  1841.) 

The  mouths  of  the  Connecticut  and  Housatonic  rivers,  and  New  Haven  Harbor,  whose 
positions  are  shown  on  the  map  on  page  211,  afford  excellent  illustrations  of  this  subject. 
The  depths  in  the  figures  are  in  feet ;  the  lines  mark  depths  of  6,  12,  18,  and  24  feet. 

The  mouth  and  sand-bars  of  the  Connecticut  Kiver  are  represented  in  Fig.  198.  The 
river  is  the  largest  of  New  England,  and  supplies  abundant  water  and  much  sediment 


WATER   AS   A   MECHANICAL   AGENT. 


227 


200. 


v^/liT  \,-'A/    24    28 
"JLJLJL-3  JHQ,.;<P  22  36        39 


But  the  wave-and-current  drift,  moving  westward,  finds  its  mouth  open  ;  and  the  sand-bars 
there  made  are  so  high  and  large  that  the  greatest  depth  in  the  channel  at  low  tide 
is  only  7  feet. 

The  mouth  of  the  Housatonic  River,  west  of  New  Haven  (a  stream  100  miles  long)  is 
in  a  worse  plight ;  for  it  gapes  open  directly  eastward  and  faces  the  drift  movement.    The 
greatest  depth  over  the  bar  at  low  water 
is  consequently  only  3  feet.     The  tide  is 
7  feet ;  but  the  tidal  grounds  are  small. 

The  harbor  of  New  Haven  (Fig.  199) 
receives  3  rivers,  the  longest  only  35  miles. 
But,  in  contrast  with  the  other  cases,  there 
is  a  prolonged  eastern  cape  of  gneissoid 
granite,  and  this  forces  the  wave-and-current 
drift  to  take  a  course  more  to  the  south- 
ward over  deeper  water.  The  drift  chokes 
up  the  mouth  of  "  West  River"  (the  west- 
ernmost of  the  three),  but  leaves  the  rest 
of  the  harbor  mostly  unharmed.  Although 
the  tidal  grounds  are  not  large,  the  entrance 
to  the  harbor  has  a  depth  over  the  bar  of  20 
feet ;  and  this  it  owes  chiefly  to  its  eastern 
cape. 

Harbor-improvement. — The  principle  at 
the  basis  of  improvements  of  harbors  at  the 
mouths  of  tidal  rivers  is  made  plain  by  the 
preceding  illustrations.  It  requires  that  there 
should  exist  for  each  the  largest  possible 
tidal  grounds,  in  order  that  there  may  be  the 

largest  possible  outflow  of  waters  for  channel  scouring  ;  and  where  not  existing,  that  they 
should  be  obtained  by  the  construction,  from  the  capes  either  side  of  the  entrance,  of  a 
breakwater  or  levee  as  far  out  as  the  depths  will  allow  ;  that  the  breakwater  should  rise 
so  little  above  low-tide  level  that  the  tide  may  freely  enter  over  it  and  fill  the  bay  ;  that 
the  windward  side  of  the  breakwater  should  have  such  a  position  and  extent  as  will  carry 
the  wave-and-current  drift  far  enough  out  to  clear  the  leeward  cape,  if  possible.  A  harbor 
with  a  large  breakwater  receives  great  aid  for  channel  scouring  from  the  waters  that  are 
piled  in  by  the  storm-winds.  These  winds  sometimes  keep  driving  in  water,  and  making 
an  undercurrent  out  of  the  channel,  through  all  states  of  the  tide.  As  to  one  or  more 
additional  channels  to  the  harbor,  the  engineer  has  to  decide  after  examination.  In  the 
case  of  a  tideless  river,  like  the  Mississippi,  the  channel  may  be  improved  by  embank- 
ments alongside  of  it ;  but  not  so  that  of  a  tidal  river. 

The  harbors  made  by  coral-reef  barriers  about  Pacific  islands  are  in  accordance  with 
the  best  models  ;  and  an  atoll  with  a  ship  entrance  to  the  lagoon  is  such  a  harbor  isolated 
in  midocean.  The  outflowing  tidal  waters  keep  the  channel  in  good  condition. 


37  40 

40 


Mouth  of  the  Housntonic. 


The  formation  of  sand-bars  in  Long  Island  Sound,  and  the  variations  in 
depth,  are  due  mainly  to  variations  in  the  velocity  of  the  outflowing  tide,  as 
partly  explained  on  page  216,  the  rivers  being  the  chief  source  of  new  material. 
But  the  position  of  the  deeper  channel  has  come  down  to  a  large  extent  from 
preceding  geological  time,  and  especially  from  the  Glacial  and  Champlain 
periods,  when  depositions  were  on  an  enormous  scale.  In  other  cases  over 
the  coast  region  the  shoals  indicate  the  forms,  and  partly  the  positions, 


228  DYNAMICAL   GEOLOGY. 

of  former  emerged  land.  Moreover,  the  eddying  of  the  wave-and-current 
flow  about  islands  has  made  long  spits  as  prolongations  of  their  points 
or  capes. 

7.  Action  of  the  oceanic  waters  over  a  submerged  continent,  and  during  a 
progressing  submergence  or  emergence.  —  Were  a  slowly  progressing  submer- 
gence of  a  continent,  or  of  any  large  part  of  one,  in  progress,  the  waves  and 
marine  currents  would  work  over  the  loose  earth,  gravel,  and  alluvium  of 
the  surface,  thereby  changing  them  into  marine  deposits ;  the  living  species 
of  the  land  and  the  fresh  waters  would  be  destroyed,  and  marine  life  would  be 
introduced ;  and  the  general  features  of  the  surface  would  be  changed  through 
a  wearing  off  of  heights  and  a  filling  of  preexisting  valleys,  and  not  by  the 
excavation  of  valleys.  It  might  be  supposed,  at  first  thought,  that  the  ocean 
would  wash  through  the  valleys  with  great  excavating  force,  arid  make  deep 
gorges  over  the  surface.  But  from  the  present  action  on  seacoasts,  it  is 
learned  that  with  each  foot  of  submergence,  the  seabeach  would  be  set  a 
little  farther  inland,  so  that  the  whole  would  successively  pass  through 
the  conditions  of  a  seashore.  The  salt  waters,  in  fact,  enter  the  river-valleys 
of  a  coast  but  a  short  distance,  because  they  are  excluded  by  the  outflowing 
stream.  During  a  progressing  submergence,  therefore,  the  ocean  would  have 
no  power  of  excavating  narrow  valleys,  unless  they  happened  to  be  open  at 
both  ends  and  of  great  breadth  and  depth,  so  as  to  allow  the  oceanic  currents 
to  sweep  through. 

In  a  subsequent  emergence,  the  mountains  and  ridges  would  be  still 
further  degraded,  and  the  valleys  tilled  by  their  debris.  The  laws  of  sea- 
coast  action  would  again  come  into  play,  and  the  wear  of  all  new  headlands 
and  the  filling  of  bays  would  continue  to  be  the  result,  so  long  as  the  emer- 
gence was  in  progress. 

If  the  continent  were  to  a  large  extent  without  mountains,  as  was  the  fact 
in  early  geological  time,  the  broad  flat  surface  might  then  lie  slightly  above 
or  below  the  tide-level  at  once,  or  nearly  simultaneously,  so  that,  under  a 
small  change  of  level,  the  waves  might  sweep  across  the  whole  area  and  the 
deposits  have  a  continental  extent.  Through  continental  oscillations,  caus- 
ing slight  emergences  of  large  areas  to  alternate  with  varying  submergences, 
variations  in  the  formations  would  be  produced,  differences  of  depths  and 
differences  of  currents  causing  transitions  from  arenaceous  to  argillaceous  or 
to  pebbly  accumulations,  or  to  clear  waters  fitted  for  corals  and  the  other  life 
which  has  contributed  to  limestone-making. 

Evidence  of  emergence  or  elevation  is  to  be  looked  for  in  the  presence  of 
stratified  beds  containing  marine  fossils ;  and  when  no  such  evidence  exists 
over  a  country,  the  proof  is  defective,  so  mucli  so,  that  facts  from  elevated, 
beach-like  accumulations  or  terraces  of  sand  or  gravel  are  not  worthy  of 
much  consideration,  unless  on  land  fronting  the  seashore.  The  sea-border 
animal  life  readily  moves  in  when  a  submergence  is  in  progress ;  for  each 
species  has  its  limits  in  depth  and  must  move  or  die,  and  ova  float  landward 
with  the  waves  and  currents ;  hence  fossil-bearing,  sea-border  deposits  would 


WATER   AS   A  MECHANICAL   AGENT.  229 

be  sure  to  form  in  favorable  places.  On  the  emergence,  these  deposits 
remain  to  mark  progress.  Beach-like  deposits  are  readily  made  by  rivers 
and  on  lake-shores. 


WORK  IN  THE  OCEAN'S  ABYSSAL  DEPTHS. 

The  bottom  of  the  ocean,  down  to  about  15,000  feet,  has  its  abundant 
life,  and  besides  is  ever  receiving  relics  in  great  profusion  from  the  pelagic 
life  of  the  waters,  and  thus  it  may  over  large  portions  be  making  limestones 
and  flint-beds ;  but  it  is  poor  in  other  geological  work.  It  feels  the  move- 
ment of  the  tidal  wave,  and  also  that  of  the  polar  flow  toward  the  equator, 
each  under  the  ocean's  heavy  pressure.  But  these  are  infinitesimal  sources 
of  force,  and  have,  therefore,  no  sensible,  mechanical  effects,  either  in  the 
way  of  transportation  or  abrasion.  The  near  convergence  of  ridges  that 
could  bring  the  waters  passing  between  them  into  a  working  condition  does 
not  exist. 

There  are  hence  no  means  of  producing  a  stratified  or  bedded  structure 
in  the  abyssal  deposits,  excepting  earthquake  vibrations,  the  results  of  which 
would  be  local,  and  variations,  with  the  passing  ages,  in  the  pelagic  or  abyssal 
life  of  the  waters,  causing  variations  in  the  showers  of  Diatoms  or  of  shells 
of  Ehizopods,  or  in  the  growth  of  Sponges  and  other  species  over  the  bottom. 
The  wide-spread  contributions  of  volcanic  ashes  from  volcanoes,  especially 
the  oceanic,  drop  to  the  bottom  and  rest  there,  undergoing  only  such  chemi- 
cal changes  as  may  go  on  at  the  temperature. 

Tidal  or  current  scour  is  limited  to  relatively  shallow  depths  or  unusual 
conditions.  Mellard  Reade  mentions  cases  of  probable  tidal  scour  at  bottom 
in  channels  between  islands  on  the  coast  of  Scotland.  But  the  depths 
do  not  exceed  800  feet.  He  also  reports  (1885)  that,  according  to  Sir 
James  Anderson,  the  undercurrent  out  of  the  Mediterranean  near  Gibraltar 
moves  the  water  to  its  bottom,  and  that  at  500  fathoms  the  wire  of  the 
electric  cable  was  ground  like  the  edge  of  a  razor,  so  that  they  had  to  aban- 
don it  and  lay  a  new  cable  well  inshore.  This  is  confirmed  by  Captain 
Nares,  who  reports  that  he  could  get  no  specimen  of  the  bottom  probably 
because  of  a  "  perfect  swirl  at  that  depth." 

The  great  oceanic  currents  carry  on  little  transportation  and  corrosion  of 
detritus,  on  account  of  their  distance  from  the  land.  The  Labrador  current, 
with  its  westward  tendency  (page  46),  acting  against  the  submerged  border 
of  the  continent,  may  have  produced  some  results  in  past  time,  if  not  doing 
so  now.  But  its  chief  geological  work  has  been  the  transportation  of  ice- 
bergs, and  that  has  not  yet  ceased.  It  has  been  supposed  that  the  course  of 
the  steep  outer  slope  of  the  submerged  Atlantic  border  has  been  determined 
by  the  oceanic  currents ;  but  it  is  far  more  probable  that  the  position  of  the 
slope  has  directed  the  courses  of  the  currents.  The  Gulf  Stream  along  the 
Florida  Straits  and  toward  Cape  Hatteras  has  a  velocity  sufficient  for  abrad- 
ing action ;  but  the  stream  does  not  carry  its  surface  velocity  to  the  bottom, 


230  DYNAMICAL   GEOLOGY. 

even  in  the  Florida  Straits.  Over  a  portion  of  the  "  Blake  plateau,"  a  region 
southeast  of  Georgia,  between  the  lines  of  100  and  600  fathoms,  the  bottom 
is  "  clean  of  mud  and  ooze,  and  almost  so  of  living  species  " ;  and  A.  Agassiz 
has  hence  suggested  that  abrasion  by  current  action  may  be  going  on  over 
it.  It  is  a  question  for  investigation. 

The  bottom  of  the  Atlantic  Ocean,  south  of  Newfoundland  and  thence 
southwestward,  has  received  droppings  of  stones,  gravel,  and  earth  from  ice- 
bergs, and  the  deposits  of  the  Glacial  period  extend  some  distance  south  of 
the  latitude  of  Cape  Hatteras.  They  consist  of  sand,  stones,  and  some  large 
bowlders  of  granite  and  other  rocks.  The  "  Challenger  "  expedition  dredged 
up  a  500-pound  bowlder  of  syenyte  in  this  region  near  latitude  41°  14'  W.,  from 
a  depth  of  1340  fathoms  (Murray,  1885).  The  "Albatross,"  of  the  United 
States  Fish  Commission,  obtained  granite  bowlders  of  50  pounds  near  71°- 
72°  W.  and  37°  40'  K  (Verrill,  1884).  In  the  Glacial  period,  even  New  York 
Bay,  and  perhaps  Delaware  Bay,  discharged  icebergs  for  transport  by  the 
Labrador  current  to  a  melting  region  on  the  borders  of  the  Gulf  Stream. 
On  the  east  margin  of  the  Gulf  Stream,  in  2000  fathoms,  the  dredge  has 
found,  as  Verrill  states,  only  the  usual  Globigerina  ooze,  and  farther  south 
toward  the  West  Indies,  the  bottom  is  no  less  free  from  continental  debris. 
But  the  modern  era  has  its  new  element,  which  has  made  exceptions  pos- 
sible over  all  the  ocean. 

Owing  to  the  presence  of  Man  in  the  world,  whose  life  is  on  the  waters 
as  well  as  the  land,  the  bottom  deposits  have  been  found  in  one  case  to  afford 
a  dredge-load  of  red  bricks.  It  was  brought  up  from  a  depth  of  1537  fathoms 
(nearly  10,000  feet)  in  the  Atlantic  in  latitude  39°  3'  and  longitude  70°  51'; 
and  Professor  Verrill,  the  reporter  (1884),  remarks  that  the  bricks  were 
probably  from  the  used-up  furnace  of  a  returning  whaler,  and  were  thrown 
overboard  when  nearing  home  after  a  whaling  voyage. 

We  are  led  by  the  facts  to  the  belief  that  in  the  cold,  dark,  still,  abyssal 
depths,  through  which  transportation  is  reduced  to  descent  by  gravity,  ooze, 
sprinkled  with  volcanic  ashes  for  concretion-making,  is  the  substitute  for 
sand,  gravel,  and  mud ;  and  where  the  means  of  biological  progress  are 
simply  strife  for  food  and  mate  and  physiological  response  to  living  work, 
there  is  excessively  slow  and  feeble  geological  change. 

III.  FREEZING  AND  FROZEN   WATER:    GLACIERS,   ICEBERGS. 

Water  performs  part  of  its  geological  work  in  the  act  of  freezing,  and 
another  part  when  frozen,  in  the  condition  of  snow  and  ice. 

WATER  FREEZING. 

1.  Displacement  and  fracturing.  —  Since  water  on  becoming  ice,  at  32°  F., 
increases  in  volume  about  -fa,  or  lineally  about  -^,  and  diminishes  in  density 
to  0'92,  whenever  freezing  takes  place  in  crevices,  it  opens  and  deepens  them, 


WATER   AS   A   MECHANICAL   AGENT. 


231 


and  thus  carries  on  a  process  of  displacement  and  destruction.  It  tears  to 
pieces  rifted,  jointed,  and  laminated  rocks,  often  separating  large  masses  ;  and 
as  most  rocks  absorb  moisture  at  the  surface,  if  not  also  through  the  mass, 
few  escape  disintegration  by  this  means  when  exposed  to  icy  weather. 
Hence  rocky  bluffs  in  cold  latitudes  have  usually  a  talus  of  broken  stone, 
while,  in  the  tropics,  this  source  of  fragments  fails.  This  kind  of  degra- 
dation has  produced  much  of  the  earth  and  coarser  loose  material  of  the 
globe. 

The  divellent  effect  of  freezing  in  fissures  may  be  increased  by  an 
addition  to  the  ice  first  formed  in  the  fissure  through  water  taken  in 
between  the  ice  and  the  rock.  The  same  interstitial  process  often  goes  on 
beneath  the  stones  of  a  pebbly  soil,  and  ends  in  lifting  them  out  of  the 
ground,  to  a  height  of  an  inch  or  two,  each  on  its  own  ice-column.  The 
process  serves  to  bring  the  stones  to  the  surface,  and  thus  has  an  assorting 
effect. 

As  a  body  of  water  35  feet  wide  will  make  a  volume  of  ice  a  foot  thick 
and  36  feet  wide,  the  freezing  of  the  surface  of  small  ponds  brings  pressure 
against  the  sides,  or  their  rocks,  and  shoves  loose  stones  up  the  shore,  making 
a  low  rampart.  It  also  causes  fractures  and  ridges  over  the  surface  of  the 
ice.  Freezing  usually  begins  about  the  shores,  and  in  its  expansion  this 
littoral  belt  of  ice  slips  over  the  water,  and  only  the  central  portion,  which, 
becomes  frozen  later,  is  thrown  into  a  strain. 

2.  Downward  creeping  of  soils  through  freezing.  —  A  displacement  or 
creeping  downward  of  the  earth  or  loose  material  on  inclined  surfaces 
is  a  common  effect  of  successive  freezings  and  thawings,  as  well  as  of 
changing  temperature  and  other  causes.  Interesting  examples  have  been 
described  from  North  Carolina  by  W.  C.  Kerr. 


201. 


202. 


203. 


Displacement  by  the  action  of  frost.    Kerr,  '81. 

Fragments  of  quartz  veins  are  here  represented  as  traveling  down  the 
slope  after  becoming  detached.  In  the  first  of  the  figures,  the  veins  have 
received  a  bend  downward  through  the  decomposition  of  the  rock,  a  mica 
schist,  and  the  slipping  movement  also  includes  the  soil.  According  to 
the  experiments  of  C.  Davison  (1889),  each  freezing  produces  a  slight 
upward  movement,  normal  to  the  inclined  surface,  and  the  thawing,  a 
vertical  settling,  and  thereby  a  displacement  downward.  The  deeper  the 
freezing  in  any  case,  the  greater  would  be  the  displacement. 


232  DYNAMICAL   GEOLOGY. 


ORDINARY  ICE. 

1.  Water  frozen  is  rock.     It  may  be  rock  of  nearly  pure  ice,  or  a  con- 
glomerate or  sandstone  with  a  cement  of  ice.     In  this  state  its  movements 
are  those  of  rock-masses,  and  the  effects  depend  partly  on  the  material 
cemented. 

2.  The  freezing  along  shores  envelops  stones  and  earth  that  lie  above 
and  below  the  water's  surface  or  that  may  fall  from  adjoining  bluffs.     With 
a  rise  of  the  water,  masses  thus  loaded  may  float  off  with  the  current,  or 
may  be  driven  up  the  land  by  a  wind,  and  make  heaps  or  ridges  of  stones. 
These  effects  occur  on  the  borders  of  both  rivers  and  lakes,  and  also  along 
seashores.     On  the  Newfoundland  coast  the  shore-masses  of  ice,  loaded  with 
stones  and  bowlders,  become  very  thick,  and  when  struck  by  an  ice-pack 
moving  down  from  the  north,  are  sometimes  pushed  a  hundred  yards  up 
a  shore ;  and  their  blows  against  the  rocky  bluffs  often  do  great  execution. 
On  the  other  hand,  cables  and  anchors  at  times  make  part  of  the  cemented 
materials  that  are  carried  away  from  the  shore  (S.  Milne,  1876). 

3.  Ice  formed  about  stones   over  the  bottoms  of  streams  or  lakes  is 
called  ground-ice  or  anchor-ice.     It  may  thicken  until  the  stones  are  floated, 
and  drift  away  with  the  current  down  stream  or  up  the  shores. 

Dams  are  made  across  rivers  at  narrows  (as  at  the  Delaware  Water  Gap) 
by  ice-masses,  when  the  ice-layer  over  streams  becomes  broken  up,  occasion- 
ing great  floods  over  the  regions  above. 

4.  The  impervious  layer  of  ice  and  frozen  earth,  which  sometimes  covers 
many  thousands  of  square  miles  in  cold  regions,  gives  waters  derived  from 
precipitation  or  melting  easy  flow  from  the  hills  to  the  rivers,  absorbing 
nothing,  and  usually  at  a  time  when  evaporation  is  at  a  minimum ;  and  thus 
the  greatest  of  river  floods  are  produced.     Further,  waters  beneath  an  icy 
crust,  receiving  accessions  from  meltings  where  rocks  outcrop  and  become 
heated  in  the  sun,   may  gather,  in  consequence  of  the  confinement,  into 
underground  streams,  and  these  streams  will  come  to  the  surface  over  any 
spot  not  frozen,  as  the  cellar  of  a  house,  and  other  places  protected  from 
the  cold. 

5.  The  ice-layer  on  a  steep  slope,  enveloping,  it  may  be,  much  gravel 
or  earth,  may  slip  down  as  a  mass,  in  a  creeping  way  or  abruptly,  when 
the  material  underneath  is  much  wet,  making  landslides. 

The  columnar  structure  characterizing  ice  is  partly  the  occasion  of  its  sudden  dis- 
appearance from  lakes  in  the  spring.  Totten  states  (1859),  respecting  the  phenomenon 
on  Lake  Champlain,  that  in  the  progress  toward  melting,  the  ice  (one  to  two  feet  thick) 
becomes  changed  into  an  aggregation  of  vertically  prismatic  crystals,  somewhat  irregular, 
which  touch  only  at  points  and  on  the  edges  ;  and  though  still  appearing  to  be  solid  a  cane 
may  be  shoved  through  it.  In  this  state,  a  heavy  wind  makes  the  ice  of  the  whole  lake 
vanish  in  a  few  hours.  The  thickness  of  the  disappearing  ice  may  be  known  from  the 
broken  ice  left  in  prismatic  fragments  fringing  the  shores. 


WATER  AS  A  MECHANICAL  AGENT.  233 

GLACIERS. 
1.   General  Features  and  Formation  of  Glaciers. 

1.  Nature  of  glaciers.  — Ordinary  glaciers  are  accumulations  of  ice  of  suf- 
ficient size  to  flow  down  from  snow-covered  elevations.  They  are  ice-streams, 
100  to  1000  feet  or  more  in  depth,  fed  by  the  snows  and  hoar  frost  of  exten- 
sive areas  above  the  limits  of  perpetual  frost.  The  half-compacted  snow  of 
the  source  is  the  neve  of  the  Swiss,  the  firn  of  the  Germans.  These  fields 
stretch  on  from  1000  to  7500  feet  below  the  snow-line,  because  they  are 
masses  of  ice  so  thick  that  they  are  not  entirely  melted  during  the  summer 
season.  Some  of  them  extend  down  between  green  hills  and  blooming  banks 
into  open  cultivated  valleys.  The  extremities  of  the  glaciers  of  the  Grin- 
del  wald  and  Chamouni  valleys  lie  within  a  few  hundred  yards  of  the  gardens 
and  houses  of  the  inhabitants. 

Each  glacier  is  the  source  of  a  stream  made  from  the  melting  ice.  The 
sub-glacial  stream  begins  high  in  the  mountains,  from  the  waters  that  descend 
through  the  ice;  finally,  it  gushes  forth  from  its  crystal  recesses,  a  full  tor- 
rent, and  hurries  along  over  its  stony  bed  down  the  valley. 

An  avalanche  is  a  mass  of  ice,  snow,  water,  mud,  and  stones  sliding  with 
crashing  sounds  from  some  point  high  up  on  the  side  of  a  mountain ;  a  glacier 
is  ice  flowing  slowly  from  a  perpetual  source.  Between  the  two  there  are 
small  glacier  patches,  lodged  in  steep  valleys,  called  hanging-glaciers  that 
never  move  far  enough  to  gain  a  descent. 

As  in  the  case  of  rivers  :  (1)  glaciers  depend  for  formation  and  size  on 
the  amount  of  precipitation,  and  on  the  size  of  the  drainage  area;  (2)  they 
take  possession  of  all  the  valleys  of  a  mountain-region  and  flow  down  slopes 
of  all  angles ;  (3)  the  ice-streams  of  the  upper  valleys  combine,  like  so  many 
tributaries,  to  make  the  large  ice-courses  or  trunk-glaciers  ;  (4)  they  suffer 
loss  from  evaporation. 

But  unlike  rivers  :  (1)  glaciers  require  for  origin  a  region  extending  above 
the  limit  of  perpetual  snow  ;  (2)  they  require  for  commencement  of  flow 
a  large  accumulation  of  the  material  of  a  stream  ;  (3)  the  conditions  for 
increase  are  best  when  the  yearly  precipitation  is  largely  snow.  Moreover, 
(4)  the  drainage  areas  are  always  small  compared  with  those  of  rivers.  The 
Aletsch,  the  longest  glacier  of  the  Alps,  and  according  to  Tyndall  the  grand- 
est, ends  in  less  than  15  miles ;  and  no  glacier  outside  of  Greenland  and  the 
Antarctic  region  exceeds  60  miles  in  length.  Further,  (5)  they  often  have 
confluent  heads  in  a  snow  and  ice  region,  and  may  have  nearly  universal  con- 
fluence over  a  continent,  as  in  a  Glacial  era. 

The  limit  of  perpetual  snow,  above  which  lie  the  snow-fields  of  the  source, 
is  in  general  near  the  line  of  32°  F.  for  the  mean  temperature  of  the  summer. 
But  it  varies  with  the  precipitation ;  for  if  this  is  small,  the  snows  of  winter 
may  be  mostly  melted  by  the  heat  even  of  a  cool  summer,  and  the  limit  may 
be  much  above  the  summer  line  of  32°  F.,  while,  on  the  contrary,  if  very 


234  DYNAMICAL   GEOLOGY. 

large,  the  snows  may  be  permanent  far  below  the  line  even  if  the  summers 
are  warm.  In  accordance  with  this  principle  the  snow-line  in  wet  southern 
Chile  is  6000  feet  lower  than  it  is  in  corresponding  latitudes  in  North 
America,  and  3000  feet  lower  than  in  Europe ;  and  in  dry  northern  Chile,  in 
latitude  33°  S.,  it  is  as  high  as  it  is  15  degrees  farther  north  (Buchan). 

But  exceptionally  snowy  winters  followed  by  a  succession  of  two  or 
more  cool  summers  may  make  accumulating  deposits  of  snow  in  some  shaded 
valleys  of  high  mountains  that  are  much  below  the  normal  limit  of  per- 
petual snow,  and  produce  temporary  accumulations  of  ice  that  have  incipient 
flow  —  a  fact  observed  in  the  White  Mountains,  N.H. 

The  height  of  the  line  of  perpetual  snow  is  18,500'  in  the  western  Cordillera  of  the 
Bolivian  Andes  near  the  equator,  and  15,920'  in  the  less  dry  eastern  ;  12,980'  on  the  south 
side  and  16,680'  on  the  drier  north  side  of  the  Himalayas  ;  12,780'  in  the  Chilean  Andes, 
near  Santiago  ;  14,760'  in  Mexico  ;  about  13,000'  in  Teneriffe  ;  8400'  on  the  northern  and 
8800'  on  the  sunnier  southern  or  Italian  slope  of  the  Alps  ;  5090'  in  Norway;  3000'  in  Lap- 
land ;  5500'  in  Alaska ;  about  2000'  to  2200'  in  Danish  Greenland,  where  the  mean  annual 
temperature  at  the  sea  level  is  between  13°  and  33°  F.,  it  being,  according  to  Rink,  at 
Upernavik,  in  72° 48'  N.,  13-3  F.;  at  Jakobshavn,  in  69°  14'  N.,  22-6  F.;  at  Godthaab,  in 
64°  8'  N.,  27-8  F.;  at  Lichtenau,  in  60°  31'  N.,  33-2  F.;  the  annual  range  of  monthly 
means,  at  Jakobshavn,  being  0-3  F.  to  45-3  F.,  and  at  Godthaab,  11-8  F.  to  48-4  F.  The 
temperature  of  the  soil  4  feet  under  ground  at  Godthaab  varies  during  the  year  between 
31-5  F.  (in  March)  and  40-1  F.  (September). 

Lowering  the  mean  temperature  of  a  place,  by  cooling  the  summers,  lowers  the  glacier- 
limit.  Great  Britain  and  Fuegia  (Tierra  del  Fuego)  are  in  nearly  the  same  latitude  ;  and 
yet,  in  Fuegia,  the  snow-line  is  only  3000'  above  the  sea.  If,  by  any  means,  the  climate 
of  Great  Britain  could  be  reduced  to  that  of  Fuegia,  it  would  cover  the  Welsh  and  Irish 
mountains  with  glaciers  that  would  reach  the  sea,  the  snow-line  being  but  1000'  to  2000' 
above  it ;  and  the  same  cause  would  place  the  snow-line  in  the  Alps  at  5000'  to  6000'  above 
the  sea,  instead  of  8400'.  This  change  of  temperature  involves  a  removal  of  tropical 
sources  of  heat,  or  an  increase  of  arctic  sources  of  cold. 

The  length  of  flow  of  a  glacier  before  it  melts  away  depends  mainly,  as 
stated  above,  on  the  thickness  of  the  ice-mass,  and  largely  because  ice  cannot 
melt  without  absorbing  an  amount  of  heat  sufficient  to  raise  the  temperature 
of  a  like  quantity  of  water  143°  F.,  the  latent  heat  of  water.  As  a  consequence 
of  this,  an  ice-mass  has  a  thin  layer  of  cold  air  about  it ;  and  if  also  covered  by 
earth,  to  shut  off  the  winds  that  aid  evaporation  and  also  to  protect  it  from 
the  sun,  the  permanence  is  greatly  increased.  An  ice-house  affords  a  fa- 
miliar example ;  and  others  are  the  dirt-covered  masses  of  ice  only  a  foot 
or  two  thick  that  linger  on  the  north  side  of  houses  at  times  from  winter 
into  April  in  the  middle  latitudes  of  eastern  North  America. 

In  the  Alps  the  glaciers  extend  down  4500  to  5300  feet  below  the  snow- 
line.  The  snows  of  the  glacier-source  in  the  mountains  take  the  half-com- 
pacted condition  of  the  neve  for  a  distance  above  the  snow-line  as  far  as 
there  are  seasonal  or  other  alternations  in  temperature  sufficient  to  produce 
occasional  meltings.  Over  the  snow-fields,  the  extreme  cold  of  winter  is 
followed  by  months  of  less  stringent  weather,  and  by  meltings  that  send 
water  down  through  the  mass  and  make  it  coarsely  granular  and  more  or  less 


WATER   AS   A   MECHANICAL  AGENT. 


235 


firm.  The  accumulations  are  stratified,  because  made  from  a  succession  of 
snow-falls.  Surfaces  exposed  during  the  intervals  between  the  falls  become 
hardened  and  often  sprinkled  with  dust,  and,  in  some  regions,  covered  with 
growths  of  the  minute  Protococcus.  It  may  be  made  straticulate  also  through 
the  drifting  of  the  snow.  Gradually  the  lower  part  of  the  neve  becomes 
consolidated  into  stratified  ice.  Besides  the  dust  from  the  winds,  the  nev6 
may  also  contain  earth  and  stones  from  avalanches ;  but  it  has  no  surface 
accumulations  of  stones,  because  those  that  fall  upon  the  neve  sink  into  it. 


204-208. 


Fig.  204.  —  Part  of  the  glacier-district  of  Mont  Blanc,  the  lighter  middle  portion  of  the  map  16  miles  long 
out  of  22  miles,  the  whole  length  ;  river  on  the  northwest  side,  the  Arve,  in  the  valley  of  Chamouni,  and  those 
on  the  southeast  side,  tributaries  of  the  Dora  Baltea;  B,  Mont  Blanc;  G,  Aiguille  du  Geant;  J,  the  Jardin; 
T,  Aig.  du  Tour;  V,  Aig.  Verte;  a,  Argentiere  Glacier;  ba,  Brenva  Gl.;  bn,  Bossons  Gl.;  bs,  Bois  Gl.; 
g,  Geant  or  Tacul  Gl.;  I,  Lechaud  Gl.;  m,  Mer  de  Glace,  upper  part  of  the  Boia  Gl.;  mg,  Miage  Gl.; 
ta,  Talefre  Gl.;  tr,  Tour  Gl.;  «,  Trieiit  Gl. 

Fig.  205.  — Section  of  the  Mer  de  Glace,  near  m  of  Fig.  204,  or  opposite  Trelaporte;  206,  section  of 
same,  near  6s  of  Fig.  204,  or  opposite  Moutanvert;  207,  view  of  the  Rhone  Glacier;  208,  profile  of  same,  c,  c, 
etc.,  being  the  transverse  crevasses,  fading  out,  and  becoming  curved  after  passing  the  cascade  at  mn. 


236 


DYNAMICAL   GEOLOGY. 


Wherever  the  mass  of  the  neve  is  sufficient  to  overcome  the  resistance  to 
motion,  the  true  glacier  begins.  The  ice  is  porous,  because  made  of  more  or 
less  closely  united  grains.  The  grains,  which  are  at  first  small,  enlarge  as 
the  stream  descends,  and  in  the  Aletsch  glacier  some  become  two  to  three 
inches  in  diameter.  (Forel,  1880,  1890.)  Moreover,  the  grains  have  a  crys- 
talline texture,  as  has  been  proved  by  examinations  with  polarized  light. 

The  porosity  of  glacier  ice  is  made  manifest  by  pouring  on  it  aniline  purple  or  indigo 
sulphate  ;  the  liquid  penetrates  it  and  gives  it  a  marbled  appearance.  The  specific  gravity 
of  the  iceberg  ice  off  the  west- Greenland  coast  has  been  found  to  be  only  0-866,  owing  to 
its  abundant  linear  cells  (Helland,  1877). 

2.  Glacier  regions.  —  In  further  illustration  of  the  general  characters  of 
glaciers,  reference  is  first  made  to  the  Alps,  the  best  known  of  glacial 
regions.  The  Swiss  Alps  are  divided  into  northern  and  southern  ranges  by 
the  east-and-west  part  of  the  valley  of  the  Rhone,  and  the  continuation  of 
the  depression  westward  along  the  Trient  and  Chamouni.  In  the  southern 
range  are  two  glacier  regions,  the  western,  of  Mont  Blanc,  and  the  much 

larger  eastern,  of  Monte  Rosa, 

209-  besides    some    much    smaller 

areas.  Mont  Blanc  has  a 
height  of  15,784  feet,  and 
Monte  Rosa  of  15,163.  In 
the  northern  range,  there  is 
the  glacier  region  of  the  Ber- 
nese Alps  (so-named  from  the 
Canton  of  Berne),  in  which 
stand  the  Jungfrau,  13,671 
feet  high  ;  Eiger,  13,045 ;  Fin- 
steraarhorn,  14,026;  and  the 
Aletschhorn,  13,800  feet. 

The  map  on  page  235 
represents  the  larger  part  of 
the  glacier  region  about  Mont 
Blanc,  with  30  to  40  of  its  50 
glaciers.  On  the  northwest 
side  is  the  valley  of  Cha- 
mouni, or  that  of  the  river 
Arve  ;  on  the  southwest,  Alle*e 
Blanche  and  Val  Ferret,  in 
Savoy.  The  summit  of  Mont 
Blanc  is  at  B.  As  just  stated, 
each  valley  in  the  ice-covered 

area  has  its  glacier.  The  largest  extends  from  Mont  Blanc,  northeastward 
to  g,  where  it  receives,  and  for  the  larger  part  is,  the  Glacier  du  Geant  (G 
being  the  Col  du  Geant).  At  m,  where  it  is  the  Mer  de  Glace,  it  receives 


Union  of  the  glaciers.     Tyndall. 


WATER  AS  A  MECHANICAL  AGENT. 


237 


the  Lechaud  Glacier  (I),  and  then  becomes  the  trunk  glacier,  called  the 
Glacier  des  Bois  (6s) .  The  Lechaud  Glacier  has  its  tributaries,  one  of  which 
is  the  Glacier  du  Talefre  (ta),  on  the  border  of  which  is  the  Jardin  (J). 
This  union  of  tributaries  is  well  shown  in  Eig.  209  (Tyndall),  which  is  so 
labeled  as  not  to  require  special  explanation.  The  glaciers  of  the  steeper 
and  warmer  Italian  slopes,  as  the  map  shows,  are  relatively  short. 

The  Monte  Rosa  ice-region  has  still  grander  glaciers.  It  is  reached  by 
a  road  from  Visp,  on  the  Ehone,  30  miles  long,  to  Zermatt.  Within  it  stand 
the  Matterhorn  or  Mont  Cervin,  14,780  feet  high,  the  Breithorn,  and  other 
peaks,  overlooking  the  Gorner  Glacier.  Fig.  210  is  reduced  from  a  plate  in 
Agassiz's  great  work  on  glaciers.  The  Gorner  Glacier  comes  in  from  the  left 
around  the  Riffelhorn,  while  on  the  right  a  tributary  glacier  is  received  from 
the  Matterhorn  region. 

210. 


The  Gorner  Glacier,  with  the  Breithorn  in  the  distance.    Agassiz. 


The  glaciers  of  the  Bernese  Alps,  like  those  of  the  Mont  Blanc  and 
Monte  Rosa  regions,  are  largest  over  the  Rhone  valley  slopes.  The  long 
river-like  Aletsch  and  Viesch  glaciers  have  their  snow-field  sources  against 
the  Jungfrau  and  other  north-side  peaks,  and  the  former  descends  to 
within  4440  feet  of  the  sea  level.  More  to  the  eastward  flow  the  two  great 
Finsteraar  and  Lauteraar  ice-streams,  which  unite  a  few  miles  from  the 
Grimsel  Hospice,  to  form  the  Aar  Glacier,  on  which  Agassiz  made  his  obser- 
vations. Sloping  northward  away  from  the  Rhone  valley,  there  are  only 


238  DYNAMICAL   GEOLOGY. 

small  glaciers  —  the  Grindelwald  and  some  others.  The  reason  for  the 
difference  in  length  between  the  glaciers  on  the  Rhone  valley  slopes  and  on 
the  slopes  outside  is  therefore  chiefly  topographical,  though  temperature 
shortens  the  small  streams  on  the  Italian  side. 

3.  Glacier  Cascades.  —  The  Rhone  glacier,  east  of  the  river  Aar,  at  the 
source  of  the  Rhone,  is  a  glacier-cataract  (Figs.  207,  208,  p.  235),  and  the 
Glacier  du  Geant,  of  the  Mont  Blanc  region,  is  another.     The  descent  of 
the  latter  is  140  feet ;  it  passes  from  the  plateau  of  the  Col  du  Geant  over  a 
vertical  rock-wall  of  the  Tacul. 

4.  Glacier  Lakes.  —  Against  the  east  side  of  the  Aletsch  Glacier  lies  Lake 
Merjelen,  a  glacier-lake.      Glacier-ice  constitutes  the  western  side  or  con- 
fining barrier  of  the  basin,  —  which  is  there  150  feet  deep,  —  and  a  moraine 
its  bottom.     Shiftings  in  the  Aletsch  Glacier  empty  the  lake  once  in  one  to 
four  or  five  years,  deluging  part  of  the  Rhone  valley. 

The  most  accessible  of  the  large  glaciers  of  western  North  America  is 
the  grand  Muir  Glacier,  described  first  by  Professor  Muir  of  California 
(1879),  and  later  by  Professor  G.  F.  Wright  (1886)  and  others.  It  descends 
to  Glacier  Bay,  at  the  head  of  Cross  Sound,  in  latitude  58°  50',  and  has  a 
width  at  the  sea  level  on  Muir  Inlet  of  about  5000  feet.  Several  streams 
are  here  united  over  a  circ  of  30  to  40  miles,  the  two  principal  coming 
from  the  northwest  and  north.  In  this  direction  is  Mount  Fairweather, 
15,500  feet  high,  while  Mount  Crillon  is  to  the  south  of  west,  15,900  feet  high. 

The  glacier  had  a  front  on  the  water  in  1886  (Wright)  250  to  408  feet  in 
height;  but  in  1890,  of  250  feet  as  the  maximum,  there  being  evidence, 
according  to  H.  P.  Gushing,  of  some  retreat  as  well  as  diminished  height 
since  1886,  the  retreat  on  one  side  amounting  to  3000  feet  (1891).  On  either 
side  of  Muir  Inlet  are  mountains  under  verdure ;  those  on  the  west  reach  a 
height  of  2900  feet,  while  on  the  east  stands  Mount  Wright,  3150  to  5000 
feet.  Over  the  latter  are  "  large  areas  of  flowers  in  full  bloom,"  "  blue-bells, 
daisies,  buttercups,  violets,  the  purple  epilobium  "  ;  and,  "  on  the  north  side 
of  a  slight  elevation,  great  masses  of  snow  were  preserved  in  the  very  midst 
of  these  brilliant  flower-gardens."  (Wright's  Ice  Age.) 

Other  grand  west- American  glaciers  are  those  of  Mount  St.  Elias  —  an  ele- 
vation over  18,000  feet  high.  The  general  features  of  the  great  Malaspina 
Glacier  are  shown  on  the  accompanying  map,  from  a  paper  by  I.  C.  Russell. 
The  glacier  is  named  after  Malaspina,  who  explored  the  coast  in  1792.  It  is 
a  great  ice-plateau  about  1500  square  miles  in  area,  and  mostly  1500  feet 
above  the  sea  level.  The  Seward  Glacier,  one.  of  its  feeders,  is  50  miles  long 
according  to  Russell,  and  the  Agassiz  and  Guyot  glaciers  were  given  the 
same  length  by  Schwatka  (1886).  From  the  point  between  the  Seward  and 
Agassiz  glaciers,  a  high  and  broad  medial  moraine  crosses  the  Malaspina 
Glacier  to  the  moraine  of  the  border  —  a  large  and  in  part  forest-covered 
region  of  stones  and  earth.  On  the  border  of  the  Malaspina  Glacier  are 
many  lakelets,  like  Merjelen,  which  crevasses  occasionally  discharge;  and 
beneath  it  are  drainage  streams.  (Russell,  1892.) 


WATER  AS  A  MECHANICAL  AGENT. 


239 


Other  glacier  regions  exist  in  the  Austrian  Alps,  the  Pyrenees,  Norway,  the  Caucasus, 
Himalayas,  New  Zealand,  the  western  mountains  of  South  America,  and  on  Greenland 
and  other  lands  in  polar  latitudes  north  and  south. 

211. 


240  DYNAMICAL  GEOLOGY. 

In  the  Himalayas,  on  the  Bahio  Glacier  in  the  Mustakh  Range,  there  are  several  large 
lakes  spread  over  the  middle  of  the  glacier  for  2  miles,  some  of  them  500  yards  long  and 
200  to  300  broad.  (Godwin-Austen,  1879.)  Colonel  Tanner  (1891)  states  that  the  glaciers 
of  the  Sat  valley  come  down  to  the  bottom  of  the  valley,  and  "forests,  fields,  orchards, 
and  inhabited  houses  are  scattered  about  near  the  ice-heaps." 

In  South  America,  the  glaciers  of  Fuegia,  first  described  by  Darwin,  reach  to  the  sea 
level.  Glaciers  occur  at  intervals  northward  along  the  Andes,  and  even  under  the  equator. 

In  North  America,  the  most  southern  glaciers  are  some  of  small  size  about  Mount 
Lyell  (13,217')  and  Mount  Dana  (13,227')  in  the  Sierra  Nevada  ;  the  length  is  from  half  a 
mile  to  a  mile.  (Muir,  1872  ;  Le  Conte,  1873  ;  Russell,  in  an  illustrated  paper  on  the  exist- 
ing United  States  glaciers,  1885.)  There  is  a  small  glacier  also  on  Mount  Shasta,  Cal. 
(14,511',  King,  1870),  and  others  on  Mount  Jefferson  (15,500')  and  Mount  Hood  (11,225') 
in  Oregon  ;  and  one  of  greater  size  about  Mount  Tacoma,  14,444'  high,  in  Washington. 

Farther  north,  on  the  same  coast,  glaciers  are  numerous.  On  the  delta  of  the  Stikine 
River,  near  latitude  57°,  as  first  described  by  W.  P.  Blake  (1868),  are  four  glaciers,  and 
one  of  these  terminates  in  a  bluff  of  ice  nearly  2  miles  long  and  150'  high.  Farther 
north  are  the  Auk  and  Patterson  glaciers,  about  latitude  58°,  the  Davidson  Glacier,  in  59° 
45',  and  many  others.  Those  about  St.  Elias  are  the  largest  glaciers  in  the  northern  hem- 
isphere outside  of  Greenland  and  the  Prince  William  Sound  Alps. 

North  of  Bering  Strait  at  Kotzebue  Sound,  lat.  66°  15',  the  ice-cliffs  are  the  edges  of 
great  sheets  of  ice,  which  extend  far  inland  and  have  2  or  3  feet  of  soil  above,  over 
which  there  is  a  luxuriant  growth  of  vegetation.  There  are  no  mountains  in  the  vicinity. 
(Kotzebue,  1818  ;  Dall,  1880.) 

Along  the  Rocky  Mountains,  small  glaciers  exist  in  the  Wind  River  Mountains,  at  the 
head  of  the  Flathead  River  in  Montana,  and  north  of  the  Canadian  Pacific  Railroad  in  the 
Selkirk  Range,  near  the  cut  through  the  mountains.  Near  54°  N.  is  the  northern  glacier 
limit  in  these  mountains. 

Greenland,  about  700,000  square  miles  in  probable  area,  has  at  least  five 
sixths  of  its  surface  continuously  covered  with  ice  (Peary).  The  only  part 
bare  is  a  strip  along  the  coast  30  to  60  miles  wide  on  the  west,  and  of  less 
width  on  the  east  and  north.  Its  annual  precipitation  is  only  7  to  10 
inches. 

In  the  accompanying  map  of  a  part  of  western  (Danish)  Greenland,  by 
Lieutenant  Jensen  (Fig.  212),  the  shaded  part,  to  the  left,  is  the  sea  (Davis 
Strait),  which  extends  up  into  many  of  the  fiords;  the  white  part  is  the  coast 
fringe,  30  miles  or  so  wide,  of  bare  land  with  its  deep  fiords  ;  the  black  is 
a  portion  of  the  interminable  ice-cap  of  interior  Greenland ;  and  the  white 
spots  in  this  part  show  where  rocky  peaks,  called  Nunatdks  in  Greenland, 
project  like  islands  through  the  icy  surface,  those  at  J  N  to  a  height  over 
5000  feet  above  the  sea,  and  100  to  500  feet  above  the  ice  around.  On  these 
Nunataks  are  growing  and  flowering  plants  of  the  genera  Ranunculus,  Poten- 
tilla,  Silene,  Saxifraga,  Papaver,  Luzula,  Oxyria,  Trisetum,  and  others.  The 
surface  rises  inland  to  5000  to  10,000  feet,  and  the  ice  pushes  shoreward.  As 
it  descends  along  the  coast,  valleys,  or  fiords,  it  takes  the  form  of  ordinary  local 
glaciers,  and  such  projecting  portions  are  the  so-called  Greenland  glaciers. 

The  larger  glacier  on  the  map,  10  to  12  miles  wide,  is  the  Frederikshaab 
Glacier ;  the  arrows  show  the  directions  of  movement  in  the  ice.  Another 
glacier  occupies  the  head  of  the  Bjorne  Sund,  or  fiord.  North  of  latitude  79° 


WATER   AS   A  MECHANICAL  AGENT. 


241 


20',  the  Humboldt  Glacier  has  a  breadth  on  the  sea  of  45  miles.  Over  the  inte- 
rior ice  there  are  small  lakes  and  rivers ;  the  latter  plunge  down  crevasses 
to  become  underglacial  streams.  Thus,  a  large  part  of  the  fiords,  on  the 
west  and  east,  and  also  on  the  north  side  of  Greenland,  as  shown  by  Peary, 
are  the  courses  of  glaciers. 

212. 


The  black  part,  ice;  white,  land;  shaded,  water;  J  N,  Jensen's  Nunataks,  or  rocky  peaks;  D  N,  Dala- 
ger's  Nunataks;  white  lines  on  the  black,  crevasses;  arrows,  glacier-flow.    J.  A.  D.  Jensen,  '79. 

The  Greenland  ice  is  in  many  places  covered  with  a  minute  Alga,  the  Protococcus 
nivalis,  and  in  some  places  so  much  of  it  lies  together  that  it  becomes  putrescent. 
There  is  also  much  dust  —  the  cryoconite  of  Nordenskiold  —  which  may  be  of  volcanic 
origin,  and  possibly  from  Hecla.  An  analysis  of  it  obtained  Silica  62-25,  alumina  14-93, 
Fe2O30-74,  FeO  4-64,  MnO  0-07,  magnesia  3-00,  lime  5-09,  soda  4-01,  potash  2-02,  phos- 
phoric acid  0-11,  sodium  chloride  0-06,  water  3-20,  which  is  near  the  composition  of  oligoclase 
with  some  hornblende,  or  pyroxene,  and  traces  of  other  ingredients.  Doctor  Rink,  the 
Danish  explorer,  says  that  out  of  the  10  inches  of  annual  precipitation  25  per  cent  are  needed 
to  supply  the  loss  from  icebergs,  and  that  the  rest  makes  up  the  amount  lost  by  evapora- 
tion and  by  the  discharge  of  waters. 

In  the  Antarctic  regions,  Captain  Ross  found  glaciers  in  lat.  75°-78°  S.,  near  long. 
170°  E.,  and  Captain  Wilkes  (1840)  reported  the  discovery,  at  intervals  between  165°  and 
100°  E.,  along  the  Antarctic  circle,  of  the  outline  of  a  great  ice-barrier  150'  to  180'  high. 
The  "Challenger"  expedition  followed  the  course  of  the  barrier  from  80°  E.  on  the 
Antarctic  circle  to  100°  E.,  thus  carrying  Wilkes's  line  20°  farther  west ;  and  on  Heard 
DANA'S  MANUAL  — 16 


242  DYNAMICAL   GEOLOGY. 

Island  (7000' high)  in  lat.  53°  10'  S.,  long.  73°  30'  E. ,  several  glaciers  were  seen  which 
came  down  to  the  coast-line,  and  made  cliffs  of  ice  on  the  shores.  On  the  New  Zealand 
Alps,  whose  peaks  are  7500'  to  12,350'  in  height,  there  are  glaciers,  of  which  the  Tasman 
is  18  miles  long  and  2  wide.  The  snow-line  is  at  5000',  and  the  ice  descends  on  the 
west  side  to  600'  above  the  sea. 

The  so-called  hanging-glaciers  occur  about  steep  slopes  of  many  glacier  regions,  as 
the  peaks  of  the  Mont  Blanc  region,  and  between  the  snow-covered  plateau  of  Norway 
and  the  sea.  Reconstructed  glaciers  (glaciers  remaines)  are  made  out  of  the  fallen  ice  of 
avalanches  by  regelation.  At  the  Jokuls  Fiord  is  a  fine  example  of  it.  Geikie,  describ- 
ing it,  says  the  ice  slips  off  in  occasional  avalanches  from  the  edge  of  the  high  snow-field 
into  the  defile,  and  there  becomes  recemented  into  a  tolerably  solid  mass,  which  moves  on 
as  a  glacier,  and  continues  to  the  sea  level. 

2.   The  Flow  of  Glaciers. 

1.  Conditions  of  flow.  —  In  addition  to  the  relations  of  glaciers  to  rivers 
already  mentioned,  there  are  the  following :  — 

^Ls  with  rivers:  (a)  Friction  impedes  flow  along  the  sides  and  bottom, 
and  consequently  the  most  rapid  movement  of  the  glacier  is  along  the  mid- 
dle portion  above.  This  effect  is  least  in  large  and  deep  streams,  and  at  a 
minimum  in  great  continental  glaciers. 

The  more  rapid  flow  of  the  middle  at  the  surface  of  the  stream  is  proved 
by  the  observation  that  a  straight  transverse  line  marked  by  poles  set  up  in 
the  ice   (ab)  becomes  a  curved  line  (cd)  in  consequence  of 
the  movement ;   also  by  the  fact  that  the  transverse  ere-         '  "  , 

vasses  of  glaciers  become  arched  in  front,  as  in  the  Rhone 
Glacier  (Fig.  207),  and  that  transverse  dirt  bands  become 
similarly  arched  (right  half  of  Figs.  205,  206,  Forbes,  Tyndall),  repre- 
senting the  condition  in  a  tributary  glacier,  the  G£ant,  after  union  with 
other  tributaries  on  the  left  (page  235).  Further,  the  retardation  at  bot- 
tom is  proved  by  the  fact  that  vertical  blocks  made  by  transverse  crevasses 
take  an  up-stream  dip,  which  gradually  increases  with  the  flow.  (Guyot, 
1838.) 

(b)  At  a  bend  in  the  stream,  the  movement  is  more  rapid  on  the  convex 
side  than  on  the  concave ;  and  the  medial  line  of  greatest  rapidity  is  nearest 
the  convex  side. 

(c)  When  the  stream  abruptly  narrows,  the  ice  above  becomes  more  or 
less  heaped  arid  slower  in  movement,  and  then  passes  the  narrows  with  an 
increased  rate  of  flow. 

(d)  On  passing  small  rocky  islets,  the   glacier  sometimes  bends  about 
the  obstacle  and  envelops  it  without  breaking,  as  in  the  case  of  two  islets 
of  rock  in  the  midst  of  the  Brenva  Glacier,  showing  a  molecular  adjustment 
in  the  ice.     (Guyot,  1838.) 

But,  unlike  rivers:  (e)  Winds  neither  impede  nor  accelerate  the  sur- 
face movement;  and  (/),  as  with  other  solid  substances,  the  yielding  to 
resistance  is  commonly  attended  by  fractures  called  crevasses,  and  by  dis- 
placements. 


WATER    AS    A   MECHANICAL   AGENT.  24£ 

2.  Lamellar  or  straticulate  structure  of  glacier-ice  modified  by  ihefloiv;  the 
" blue  bands"  or  " veined  structure"  —  The  ice  of  a  glacier,  as  first  observed 
by  Guyot   (1838),  is  often  vertically  laminated  parallel  to  its  sides,  and 
sometimes  so  delicately  that  the  ice  appears  like  a  semi-transparent  striped 
marble  or  agate.     The  layers  are  alternations  of  cellular  (or  snowy)  ice  and 
clear,  bluish,  solid  ice,  and  an  indication  of  the  porosity  of  a  glacier.     The 
melting  of  the  surface  sometimes  leaves  the  ledges  of  the  more  solid  layers 
projecting.     This  is  well  seen  either  side  of  the  middle  portion  of  the  Mer 
de  Glace,  and  in  the  Brenva  and  Aar  glaciers.     Guyot  found  the  structure 
in  the  ice  of  the  summit  of  the  Gries  Glacier  at  a  height  near  7500  feet. 
He  concluded  that  the  layers  were  made  from  the  daily  driftings,  deposi- 
tions, and  hardenings  of  snow  over  the  neve  region ;    that  they  were  origi- 
nally horizontal  or  parallel  to  the  surface  of  the  glacier,  as  in  the  bedding 
and  straticulation  of  a  shale ;  and  that  the  various  positions  assumed,  includ- 
ing parallelism  to  the  sides  of  the  valley,  were  probably  a  consequence  of 
the  flow,  and  of  the  greater  velocity  at  middle.     The  structure  is  attributed 
by  Tyndall  to  the  pressure  to  which  the  ice  is  subjected  in  making  its  way 
between  the  walls  of  a  valley ;  but  regions  present  it  that  have  had  no  such 
pressure. 

The  view  that  the  movement  of  glaciers  was  essentially  like  that  of  rivers  or  "  soft- 
ened wax  "  was  announced  by  Bordier  in  1773  ;  and  afterward  more  fully,  with  a  specific 
recognition  of  the  idea  of  plasticity  in  the  ice,  and  of  the  influence,  on  the  movement,  of 
friction  at  bottom  and  along  the  sides,  by  Rendu,  in  a  memoir  read  before  the  Academy 
of  Sciences  of  Savoy,  in  1841.  Hugi,  in  1827,  built  a  hut  on  the  Aar  Glacier  to  determine 
its  rate  of  motion;  and  found  the  movement  330'  in  three  years,  and  2354'  in  nine  years. 
Guyot  made  his  early  observations  in  1838,  and  drew  up  a  paper  containing  his  conclu- 
sions ;  but  failed  to  publish  it  because  of  his  giving  the  field  up  to  his  friend  Agassiz.  (See 
Memoir,  U.  S.  Nat.  Acad.,  1886  ;  Am.  Jour.  Sci.,  1886  ;  and  Smiths.  Inst.,  1889.)  Agassiz 
commenced  in  1841  his  grand  series  of  observations  on  the  Aar  Glacier,  measuring  the 
rate  of  movement  in  a  section  across  the  glacier ;  and,  on  July  4,  1842,  his  first  results, 
proving  the  more  rapid  flow  of  the  middle  portion  (his  6  poles  in  the  line  across  having 
moved  severally  160',  225',  269',  240',  210',  and  120'),  were  published  in  the  Comptes 
Rendus.  His  investigations  were  continued  for  several  years  afterward ;  and  in  1847 
appeared  his  first  great  work,  entitled  Systems  Glaciaire.  Professor  Forbes  visited 
Agassiz  at  his  work  on  the  Aar,  in  1841,  and  in  the  summer  of  1842  undertook  an  inde- 
pendent investigation  on  the  Mer  de  Glace,  near  Chamouni ;  and  in  October  of  1842  his 
measurements,  confirming  those  of  Agassiz,  were  published.  A  year  afterward,  in  1843, 
appeared  his  Travels  in  the  Alps,  in  which  his  various  careful  observations  are  given 
in  detail,  and  the  theory  of  glaciers,  on  the  principle  that  the  ice  moves  like  a  viscous 
fluid,  is  fully  elucidated.  His  later  writings  on  the  subject  are  contained  in  a  volume 
entitled  Occasional  Papers  on  the  Theory  of  Glaciers.  Later,  Tyndall  made  a  further 
series  of  measurements  and  observations  in  the  Alps,  demonstrating  the  influence  of 
bends  in  a  glacier,  and  explaining  other  glacial  phenomena.  His  views  are  contained  in 
The  Glaciers  of  the  Alps,  1860,  and  The  Forms  of  Water,  1872. 

3.  Rate  of  flow.  —  The  rate  of  descent  in  the  mass  of  a  glacier  in  the  Alps 
varies  from  one  or  two  inches  a  day  to  over  50 ;  it  is  about  half  as  much  in 
winter  as  in  summer.    Ten  to  twenty  inches  a  day  in  the  warm  season  is  most 


244  DYNAMICAL   GEOLOGY. 

common;  twelve  inches  corresponds  to  365  feet  a  year,  or  one  mile  in  about 
14^  years. 

Forbes  found  for  the  maximum  in  July,  at  his  upper  station  on  the  Bois 
Glacier,  52-1  inches  a  day,  and  in  December  11-5  inches.  In  the  large  Muir 
Glacier,  according  to  G.  F.  Wright,  the  average  in  August,  1886,  was  20  feet 
per  day;  and  according  to  H.  F.  E-eid,  in  August,  1890,  10  feet. 

The  Greenland  glaciers  are  rapid  in  movement  because  the  outlets  from 
the  great  interior  mass  are  so  narrow.  At  Disco  Bay,  the  Jakobshavn  Glacier 
moves  in  summer  at  middle  65  feet  per  day,  and  a  fourth  of  a  mile  from  the 
side,  nearly  50  feet.  Helland  estimated  the  daily  discharge  of  ice  into  the 
sea,  as  icebergs,  at  432,000,000  cubic  feet.  Bates  of  35-70  and  100  feet  per 
day  have  been  reported.  The  rate  of  99  feet  per  day  was  observed  in 
August,  1887,  in  the  fiord  east  of  Upernavik  by  the  Danish  Lieutenants, 
Eyder  and  Bloch.  In  glaciers  of  so  great  magnitude  friction  is  reduced  to  a 
minimum. 

In  the  summer  the  snow  over  the  ice  melts,  sending  streams  and  drippings 
down  the  crevasses  and  into  all  accessible  cracks  in  the  ice ;  as  far  within  as 
the  outside  heat  penetrates,  the  many  air-cells  inside  warm  up  and  melt  the 
ice  around  them,  and  the  dirt  grains  and  all  foreign  substances  absorb  and  use 
the  heat  in  like  manner.  Moreover,  the  glaciers  lose  much  at  surface  by 
evaporation. 

4.  Intermittent  advance.  —  In  glaciers  the  cycle  of  advance  and  retreat  is 
many  years  in  length.     The  meteorological  conditions  favoring  maximum 
mass  of  neve,  and  thereby  maximum  rate  of  flow  and  elongation,  are,  as 
already  explained :  first,  long  and  wet  winters  in  the  neve  region,  causing  an 
extension  of  the  n&ve  area,  which  is  that  of  the  only  permanent  annual  con- 
tributions, and  which  has  great  breadth  compared  with  that  of  the  trunk 
glacier  below ;  second,  short  and  dry  summers,  especially  below  the  level  of 
the  n6ve.     Thus  come  the  largest  gain  and  the  smallest  loss. 

Observation  has  proved  that  the  cycle  of  gain  and  loss  is  a  long  one,  20 
to  50  years.  Forel  has  reported  that  in  the  Alps  there  have  been  in  this 
century  five  half  cycles  ;  1800  probably  to  1815,  enlargement ;  1815-30,  dimi- 
nution; 1830-45,  enlargement;  1845-75,  diminution;  and  that  from  1875 
to  1890  enlargement  was  beginning  in  different  glaciers.  He  observes  that 
the  alternating  periods  correspond  to  that  of  a  cold  and  rainy  period,  and 
that  of  a  warm  and  dry,  as  meteorologically  deduced  by  C.  Lang  (1886). 

5.  Capability  of  flow  in  an  ice-mass.  —  Yielding  to  gravity  in  material  so 
solid  as  the  ice  of  a  glacier,  over  uneven  slopes  and  along  valleys  ever-vary- 
ing in  obstacles,  is  explained  on  the  ground  of  the  following  qualities  of  ice 
and  glaciers,     (a)  The  fragility  of  ice,  in  consequence  of  which  it  breaks 
readily  and  so  accommodates  itself  to  obstacles ;   (6)  the  dissemination  of 
much  water  through  the  mass  of  the  glacier,  which  increases  the  fragility  and 
approximates  the  condition  to  that  of  a  viscid  body ;   (c)  the  plasticity  of  ice, 
or  the  quality  of  molecular  adaptation  to  conditions  of  pressure ;   (d)  slip- 
ping along  planes  of  bedding  or  straticulation  in  the  ice ;   (e)  sliding  of  the 


WATER   AS    A  MECHANICAL  AGENT.  245 

glacier  along  the  under-glacier  surface ;  (/)  a  local  melting  of  ice,  as  a 
consequence  of  the  accumulation  of  pressure,  diminishing  thereby  resistance 
and  facilitating  motion. 

(a)  Fragility  of  ice.  —  Reaching  a  place  of  steep  descent,  great  transverse 
blocks  of  a  glacier  drop  in  succession.  Rounding  a  projecting  angle  in  a 
valley,  the  ice  is  compressed  at  the  side  of  the  short  turn,  and  drawn  out  on 
the  opposite  side,  and  in  the  latter  great  crevasses  are  opened.  Forbes  men- 
tions one  chasm  500  feet  wide  extending  across  the  Mer  de  Glace.  Passing 
narrows,  the  quickened  motion  causes  irregular  cross-fractures  often  in  great 
numbers.  Flowing  along  a  valley  the  resistance  of  the 
sides  (gg',  gg',  Fig.  213),  together  with  the  more  rapid  flow  2i3 

at  the  center,  makes  crevasses  (ccf)  pointing  obliquely  up 


/ 


stream  at  angles  of  about  45°.     The  direction  of  the  pull 

tending  to  produce  the  fractures  (or  that  of  greatest  ten- 

sion)  is  oblique  toward  the  center  down  stream.     Hopkins 

has  shown  that  this  pull   (pp1)   is  strongest  theoretically 

when  it  makes  an  angle  of  45°  with  the  sides  of  the  glacier, 

and  therefore  the  crevasses  are  at  45°  with  the  sides  up 

stream.     This  angle  would  be  modified  by  the  form  of  the     y  $ 

bottom,  and  by  its  pitch. 

After  being  extensively  broken  up,  the  glacier,  on  reaching  a  broader  por- 
tion of  the  valley,  of  gentler  pitch,  becomes  again  solid  by  a  general  welding 
of  the  pieces.  The  welding  process,  called  by  Faraday  regelation,  requires 
only  pressure,  and  takes  place  whether  the  surfaces  are  moist  or  dry.  (Hunger- 
ford,  1882.)  If  a  block  of  ice  is  supported  at  its  two  ends,  and  a  fine  wire 
is  passed  around  it  at  middle  and  weighted  below,  the  wire  will  slowly  melt 
its  way  through  ;  but  when  the  cut  is  completed,  the  mass  will  be  as  solid  as 
at  the  outset,  regelation  having  gone  forward  above  the  wire.  The  multi- 
tudes of  fractures  made  in  a  glacier  on  steep  slopes  hence  disappear  below 
where  the  motion  is  slow  and  the  ice  feels  the  pressure  from  above. 

(6)  Permeating  water.  —  As  already  explained,  the  summer's  heat  pro- 
duces water  over  a  glacier,  and  through  all  its  crevasses  and  smallest  crevices, 
especially  during  the  daytime.  At  night,  when  the  source  of  heat  is  with- 
drawn, there  may  be  much  refreezing  ;  but  the  days  in  summer  are  much 
longer  than  the  nights.  The  chief  source  of  the  water  largely  fails  in  winter, 
and  hence  the  difference  in  the  summer  and  winter  rates  of  movement.  The 
melting  from  local  pressure  is  an  addition  to  the  amount  of  water,  and  just 
where  needed  to  meet  special  resistance.  The  pressure  of  one  atmosphere 
lowers  the  melting-point  of  water  0-0042°  F. 

(c)  Plasticity.  —  Ice  may  be  made  by  pressure  to  copy  a  seal,  like  wax  ;  or 
by  forcing  it  through  holes  to  take  the  form  of  a  cylinder.  Kane  mentions, 
in  his  Arctic  Explorations,  the  case  of  a  table  of  ice,  eight  feet  thick  and  20 
or  more  wide,  supported  only  at  the  sides,  which,  in  two  months,  had  the 
center  depressed  by  gravity  five  feet.  The  temperature  during  the  interval 
was  Tnany  degrees  below  32°  F.  Guyot  concluded,  from  the  flow  of  the 


246  DYNAMICAL  GEOLOGY. 

glacier  around  the  two  rocky  islets  in  the  Brenva  Glacier  (south  of  Mont 
Blanc),  that  the  movement  was  by  molecular  displacement. 

(d)  Slipping  along  planes  of  bedding  or  straticulation,  or  those  of  the  blue 
bands.  —  This  slipping  has  been  shown  to  be  a  fact  in  several  glaciers,  by 
Forel  (1889)  ;  among  them,  the  Bossons  Glacier  at  Chamouni.     In  the  lower 
part  of  a  glacier  these  planes  have  a  dip  up  stream,  and  as  a  consequence 
the  mass  of  the  glacier  above,  as  it  flows  along,  rises  by  slipping  along  one 
or  more  of  the  planes  of  lamellar  structure. 

Mr.  Forel  observes  that  the  fact  explains  the  difference  of  velocity 
between  the  upper  and  lower  beds ;  the  little  movement  at  the  extremity  of 
a  glacier ;  the  reappearance,  at  the  surface,  of  bodies  buried  in  the  interior 
of  the  glacier ;  and  the  preservation  of  the  thickness  of  the  ice  at  the  lower 
extremity,  notwithstanding  the  annual  loss  from  melting.  The  cause  must 
have  great  influence  over  the  direction  of  crevasses,  and  in  all  adjustments 
to  resistances  (1889).  Guyot  described  (1832)  the  up-stream  dip  of  the 
stratification  at  the  termination  of  a  glacier,  and  attributed  to  it  the  origin 
of  the  caverns. 

(e)  Sliding  along  the  bottom  of  the  valley.  — By  the  preceding  methods,  the 
ice  might  move  by  yieldings  and  adaptations  to  surfaces,  and  not  necessarily 
move  on  the  surface  beneath  so  as  to  abrade  it.     But  the  amount  of  abrasion 
in  glaciated  regions  shows  that  these  means  of  yielding  and  adaptation  only 
help  toward  an  actual  flow  or  sliding  of  the  material  along  its  valley  in 
river-like  style. 

(/)  Movement  through  the  dilatation  of  freezing  in  the  permeating  water  of  a 
glacier.  —  This  cause  of  movement  was  appealed  to  by  Agassiz,  and  has  been 
sustained  by  others.  It  has  taken  a  new  form  through  Forel,  who  has  sug- 
gested that  movement  may  be  produced  by  the  freezing  of  water  between  the 
large  crystalline  grains  constituting  the  glacier.  Freezing  at  night,  accord- 
ing to  the  view,  by  expanding  the  mass,  would  force  the  glacier  forward. 
The  fact  that  the  grains  are  so  much  larger  in  the  lower  than  in  the  upper 
part  of  the  glacier  is  supposed  to  favor  it ;  but  this  is  far  from  conclusive. 
Forel  proposes  to  give  the  subject  further  investigation. 

With  regard  to  the  motion  of  glaciers,  Canon  Moseley,  after  experimenting  on  the 
shearing  force  of  pure  ice,  and  making  it  too  great  to  be  overcome  by  gravity  alone,  pre- 
sented a  view  that  glaciers  descend  as  a  plate  of  lead  descends  a  sloping  surface,  through 
alternate  changes  of  temperature,  the  movement  from  expansion  by  heat  being  mainly 
downward  because  of  gravity,  and  contraction  working  the  same  way.  To  this  theory 
the  obvious  objection  holds,  as  has  been  observed,  that  glaciers  do  not  undergo  the  needed 
change  of  temperature. 

Professor  Croll,  in  his  Climate  and  Time  (and  in  earlier  memoirs)  accepts  Moseley's 
deduction  as  to  the  shearing  force  of  ice,  and  brings  forward  a  molecular  theory  to 
account  for  the  motion  of  glaciers.  He  says :  "  We  find  that  the  heat  applied  to  one 
side  of  a  piece  of  ice  will  affect  the  thermal  pile  on  the  opposite  side  "  ;  and  explains  this, 
not  by  radiation  through  the  ice,  but  on  the  view  that  the  heat  applied  passes  from  mole- 
cule to  molecule  through  the  mass ;  the  transmission  of  the  heat-energy  conveyed  by  A  to 
B  melts  B,  but  crystallizes  A,  and  so  it  goes  on  through  the  ice.  Gravitation  is  the  source 


WATER   AS   A   MECHANICAL   AGENT.  247 

of  motion  ;  the  expansion  of  the  crystallizing  molecule  aids  it ;  and  the  shearing  force  is 
lost  by  the  molecular  melting.  But  it  seems  to  be  hardly  probable  that  a  glacier,  hun- 
dreds of  feet  thick,  could  be  thus  urged  forward.  Any  crevasse  or  crack  would  intercept 
the  molecular  transmission ;  and  the  cause  would  hardly  have  a  chance  to  act  in  a 
crevassed  glacier  like  the  Mer  de  Glace.  Professor  Croll,  however,  explained  the  forma- 
tion of  crevasses  on  the  same  principle. 

Avalanches,  like  other  kinds  of  landslides,  do  rapid  denuding  work  over 
the  slopes  they  descend,  ice,  water,  mud,  and  stones  hurrying  on  together, 
each  in  deluge-like  form,  with  destructive  effects.  The  noted  avalanche  of 
the  12th  of  July,  1892,  at  St.  Gervais,  in  Switzerland,  was  more  a  discharge 
of  water  than  of  ice  and  mud.  The  water  occupied  two  great  cavities  or 
reservoirs  in  the  ice  and  was  the  occasion  of  the  disaster.  The  cavities  had 
been  made  by  gradual  melting. 

The  movement  of  glaciers,  although  so  slow,  may  be  illustrated  by  com- 
parison with  that  of  pitch.  Pitch  will  not  only  descend  all  slopes,  but  will 
flow  over  a  horizontal  surface  if  the  supply  of  material  is  kept  up ;  and 
in  case  the  area  is  a  depression,  it  will  fill  the  depression,  and  then  flow  on 
beyond  it.  So  it  is  with  the  glacier.  If  there  is  a  deep  basin  in  a  glacier 
valley,  the  glacier  will  move  on  over  the  ice-filled  basin  as  if  it  were  not 
there.  While  the  mass  of  a  glacier  is  flowing  in  accordance  with  the  surface 
slope,  a  lower  portion  lying  in  a  channel  oblique  to  the  course  will  take,  if 
friction  does  not  prevent,  the  course  of  the  channel,  for  the  reason  that  it 
cannot  get  out  of  the  channel  or  valley  to  flow  otherwise.  (The  principle  is 
easily  verified  by  means  of  pitch.)  Thus  in  the  same  part  of  the  glacier  an 
upper  portion  may  have  a  different  course  from  the  lower  in  spite  of  the 
resistance  to  be  overcome. 

3.   Denudation,  Transportation,  and  Deposition. 

The  weight  of  the  glacier  makes  it  a  tool  of  great  power.  The  pressure 
for  100  feet  of  ice  in  height  is  about  40  pounds  to  the  square  inch,  and  for 
1250  feet,  500  pounds. 

A  glacier  obtains  its  material  for  transportation  both  (1)  passively,  and 
(2)  aggressively,  through  its  power  of  denudation. 

In  a  passive  way  (a)  it  receives  from  overhanging  bluffs  and  adjoining 
ridges  a  great  amount  of  earth,  stones,  and  rocks,  which  the  frost,  waters, 
and  other  causes  may  have  loosened ;  and  where  the  glacier  extends  down 
far  below  regions  of  vegetation,  it  may  have  contributions  of  vegetable  debris 
and  animal  relics.  (6)  The  winds  contribute  dust,  (c)  Freezing  in  the 
colder  season  or  in  the  advance  of  a  glacier  may  add  gravel  and  stones  that 
lie  along  its  side  or  underneath  it,  a  method  of  acquisition  which  has  its 
maximum  in  an  avalanche,  (d)  The  materials  received  may  descend  opened 
crevasses,  either  by  falling  down,  or  by  being  carried  in  descending  waters. 

Aggressively,  the  glacier  augments  its  load  (a)  by  abrasion,  carried  on 
by  means  of  the  stones  with  which  its  sides  are  armed,  or  those  that  may  lie 
between  the  glacier  and  the  rock  against  which  it  moves ;  it  thus  occasions 


248  DYNAMICAL   GEOLOGY. 

the  undermining  of  bluffs,  and  consequently  large  falls  of  rock  and  other 
debris.  (6)  It  works  with  greater  results  through  impact  or  forward  thrust 
of  its  bottom,  sides,  and  front;  for  it  thus  tears  off  angular  stones,  slate,  and 
great  rocks,  from  rifted,  laminated,  and  jointed  terranes  that  are  alongside 
or  extend  up  in  ledges  into  the  glacier,  and  takes  them  into  its  mass ;  it  also 
plows  into  weakly  consolidated  deposits,  such  as  fragile  sandstones,  and 
gathers  other  supplies,  though  not  able  deeply  to  abrade  the  harder  rocks ; 
and  in  its  movement  up  the  under-glacier  slope  of  a  ridge  or  peak,  it  bears 
along  stones  and  other  materials  from  low  levels  to  high,  (c)  Further,  it 
works  by  corrosion,  in  its  ever-shifting  and  crevassing  movements,  grinding 
stone  against  stone  or  grain  against  grain,  rounding  angles  and  making  the 
finest  of  earth  called  rock-flour,  which  may  become  clayey  by  partial  decom- 
position of  the  feldspar  present. 

The  material  gathered  by  the  ice  is  called  moraine  material.  The  larger 
part  in  ordinary  glaciers  lies  along  or  near  the  borders  and  constitutes  the 
lateral  moraine  ;  that  occurring  along  the  bottom,  in  the  glacier  and  that 
pushed  along  by  it,  is  the  ground  moraine;  and  the  deposit  accumulated 
at  the  extremity  of  the  glacier,  the  melting  place,  is  the  terminal  moraine. 
The  moraine  material  thus  deposited  is  not  stratified ;  but  it  has  a  linear 
order ;  for  it  lies  in  lines  which  point  upward  to  the  summits  from  which  its 
materials  were  gathered.  The  terminal  moraine  is  a  low  ridge,  belt,  or 
mound  of  stones  and  earth  transverse  to  the  valley.  Agassiz  observes  (1840) 
that  on  the  retreat  of  a  glacier,  a  new  moraine  may  form  each  year.  He  also 
mentions  the  fact  that  the  stones  over  the  surface  of  a  glacier  outside  of  the 
lateral  moraine  gradually  move  obliquely  toward  the  latter,  owing  to  the 
greater  velocity  at  the  center. 

When  two  glaciers  join,  the  lateral  moraines  of  the  two  uniting  sides 
become  one  medial  moraine.  The  number  of  moraines  on  a  glacier,  therefore, 
can  never  exceed  the  number  of  coalesced  glaciers  by  more  than  one.  An 
isolated  peak  rising  above  a  glacier  will  send  off  its  stones  and  earth  all  in  a 
single  line  or  moraine.  In  the  view  of  the  Gorner  Glacier  on  page  237,  the 
nearest  moraine  is  that  of  the  Kiffelhorn ;  the  second  is  a  union  of  moraines 
of  the  Gornerhorn  and  Porte  Blanche ;  the  third,  a  union  of  two  moraines 
from  two  Monte  Eosa  glaciers  ;  the  fourth,  the  great  moraine  of  the  Breithorn, 
the  summit  in  the  middle  of  the  view.  Other  moraines  may  be  seen  in  the 
distant  part  of  the  glacier.  Fig.  209  shows  the  moraines  of  the  Mer  de 
Glace  and  of  the  glaciers  above  it. 

The  transported  masses  of  rock  sometimes  have  great  magnitude.  One 
among  those  of  the  Alps  contained  200,000  cubic  feet.  In  the  lower  part  of 
the  Glacier  of  the  Aar,  after  the  junction  of  the  great  glaciers  of  the  Fins- 
teraar  and  Lauteraar,  the  medial  moraine  is  100  to  250  yards  wide  and  has  a 
height  of  100  to  140  feet  above  the  general  surface  of  the  ice  either  side. 
The  wasting  of  the  ice  of  a  glacier  by  melting  often  leaves  the  broader  stones 
perched  up  on  ice-columns  (like  the  perched  stones  in  Figs.  158,  159),  the 
stones  having  protected  the  ice  beneath  it  from  the  sun. 


WATER  AS   A  MECHANICAL   AGENT. 


249 


214. 


A  remarkable  example  of  the  carrying  of  stones  up  an  under-glacier  slope  is  afforded 
by  the  region  of  the  "  Nunataks  "  of  Greenland  (map,  page  241).  The  dotted  belts  on  the 
following  figure  (ra',  ra",  m'",  miv)  repre- 
sent belts  of  moraine  made  by  this  process ; 
and  the  nunataks  #,  ft,  i,  &,  Z,  ra,  are  emerg- 
ing peaks  of  the  covered  ridges.  The  moraine 
m'"  was  made  by  a  submerged  peak.  The 
stones  are  not  like  those  from  the  nunataks. 
They  came  up  from  varying  depths  in  the 
ice.  Some  of  them  are  20  feet  across.  The 
stones  of  the  nunatak  moraines  disappear 
down  crevasses  after  200  to  300  yards  of 
sunlit  travel,  or  bury  themselves  in  the  ice. 

In  a  similar  way,  where  a  glacier  crosses 
marine  channels,  shells  gathered  into  the 
ice  might  be  carried  along  to  the  tops  of 
the  elevations  over  the  land;  or  possibly, 
loose  sea-border  material  beneath  might  be 
pushed  up  by  the  glacier. 


The  abrasion  carried  on  by  the 
stones  in  the  sides  of  the  glacier 
planes  off,  polishes,  grooves,  and  often 
profoundly  channels,  the  rocks  either 
side  or  below;  and  these  scorings 
are  evidence  of  the  direction  of  move- 
ment. An  example  of  the  grooves  or 
scratches  is  represented  in  Fig.  215. 


Nunataks,  or  isolated  peaks,  g,  h,  i,k,  I,  m,  situated 
like  islands  in  the  Greenland  ice.    Jensen. 


Crossing  lines,  which  are  not  unfre- 
quently  observed,  are  produced  when  glaciers  spread  widely  over  a  broad 
region,  and,  owing  to  change  in  the  thickness  of  the  ice  or  some  other  cause, 
there  is  a  change  of  direction  in  the  movement. 


215. 


Glacier  groovings  or  scratches. 

Moreover,  the  stones  or  rock-masses  that  do  this  work  of  abrasion  become 
smoothed  and  scratched  or  grooved;   and  thereby  may  show  their  glacier 


250 


DYNAMICAL   GEOLOGY. 


origin.  Subsequent  abrasion  by  a  sub-glacial  or  glacier-fed  stream  may,  how- 
ever, remove  the  scratches  from  the  stories.  The  ledges  underneath,  or 
especially  their  harder  portions,  are  often  made,  by  glacial  abrasion,  into 
rounded,  grooved  knolls,  called  sheep-backs  (roclies  moutonnees)  in  allusion 
to  their  forms.  They  are  a  prominent  feature  of  all  glacial  regions ;  and 
those  of  the  Glacial  period,  when  they  were  formed  over  a  vast  extent  of 
country,  are  sometimes  preserved  to  the  present  time  in  great  perfection. 
The  view  (Fig.  216),  from  a  photograph  obtained  by  the  Hayden  expedition 
in  1873,  represents  a  portion  of  a  great  crouching  flock  of  them,  extending 

216. 


View  on  Roche-Moutonn^e  Creek,  a  tributary  of  Eagle  River,  Colorado. 

for  2000  feet  along  a  valley  leading  down  from  the  "  Mountain  of  the  Holy 
Cross,"  one  of  the  prominent  summits,  12,485  feet  high,  in  the  mountains 
of  Colorado. 

A  glacier,  too,  may  have  water-falls  in  crevasses  (and  sometimes  in  well- 
like  shafts,  formed  in  crevasses),  which  not  only  carry  down  moraine  material, 
but  excavate  the  rocks  underneath.  They  may  thus  make  broad  basins  or 
channels  in  the  rocks  as  the  glacier  moves  on  its  way ;  but  without  stopping 
its  march  for  a  few  centuries  the  fall  cannot  bore  out  a  "  pot-hole  "  like  the 
pot-holes  of  river  origin ;  for  these  require  a  stationary  tool,  they  being  ordi- 
narily as  well-centered  as  if  bored  by  a  revolving  bit. 

Deposition  from  the  glacier  takes  place  through  the  melting  of  the  ice,  as 
in  the  making  of  the  deposit  of  terminal  moraine,  above  explained.  Deposits 
are  also  made  through  crevasses,  and  the  waters  of  any  super-glacier  rivers 
or  lakes  may  add  to  the  contributions.  The  descending  waters  carry  down 


WATER   AS   A  MECHANICAL  AGENT.  251 

the  rock-flour,  which  often  makes  the  water  discharged  by  under-glacier 
streams  look  milky.  The  coarser  earth  within  the  glacier  is  added  to  the 
bottom  deposits,  making  thereby  the  unstratified  mixture  of  earth,  stones, 
and  clayey  rock-flour,  which  is  called  bowlder-day  or  till. 

The  retreats  of  a  glacier,  during  which  depositions  of  a  large  amount  of 
moraine  material  take  place,  afford  an  opportunity  for  the  growth  of  plants, 
and  sometimes  even  forests,  over  the  deserted  moraines,  and  for  the  spread- 
ing out  of  stratified  gravel  and  earth  by  the  sub-glacial  river  and  other 
means,  so  that,  whenever  the  advance  takes  place,  stumps,  trunks  of  trees, 
and  stratified  beds  become  again  under  the  ice  and  new  deposits  of  bowlder- 
clay  are  made.  The  Muir  Glacier,  according  to  Wright  and  others,  affords 
remarkable  examples  of  such  intercalations  of  dismantled  forests  and  gravel- 
beds,  and  Kussell's  account  and  map  of  the  St.  Elias  Glacier  (page  238) 
illustrate  the  process. 

4.   Denudation  and  Transportation  by  Glacier-made  Rivers. 

The  greater  part  of  the  excavation  of  valleys  carried  on  in  glacier  regions 
is  due  to  the  glacier-made  rivers.  They  swell  by  the  summer  melting,  and 
become  violent,  plunging  torrents,  and  thus  produce  great  and  rapid  work, 
while  the  glacier  is  slowly  creeping  along,  and  as  they  bear  the  material 
down  stream,  it  becomes  deposited  and  stratified  like  other  fluvial  deposits. 
Violent  effects  come  from  the  damming  of  streams  by  the  snow  and  ice  of 
Alpine  valleys ;  for  in  no  other  way  can  barriers  be  thrown  so  readily  across 
profound  valleys.  The  deluges  caused  by  the  accumulated  waters,  when  they 
break  loose,  are  often  very  destructive.  The  Alps  are  full  of  examples. 
Again,  the  valleys  are  sometimes  dammed  up  by  great  moraines,  making 
lakes ;  and  such  lakes  sometimes  break  through  their  barriers,  and  flood  the 
valley  below  with  tearing  waters.  The  lakes  of  the  glacier's  surface  may 
add  suddenly  to  the  sub-glacial  waters,  and  produce  great  destruction  and 
widespread  stratified  deposits. 

The  amount  of  rock-flour  and  coarser  sediment  discharged  daily  by  the 
Aar  Glacier  in  August  has  been  estimated  to  be  280  tons ;  from  the  Justedal 
Glacier,  in  Norway,  in  July,  about  3^  times  as  much ;  from  some  Greenland 
glaciers,  varying  up  to  75  times  as  much  as  the  Aar. 

ICEBERGS. 

A  glacier  on  a  seacoast  often  stretches  out  its  icy  foot  into  the  ocean; 
and,  when  this  part  is  finally  broken  off,  by  the  movement  of  the  sea  or 
otherwise,  it  becomes  an  iceberg.  The  break  takes  place  usually  in  the 
fiords,  where  the  glaciers  extend  out  into  the  deep  water  and  are  largely 
submerged.  The  icebergs  carry  away  the  stones  and  earth  which  the  glacier 
may  have  gathered,  and  transport  them  often  to  distant  regions,  whither  they 
are  borne  by  the  polar  oceanic  currents.  Most  of  those  of  Greenland,  how- 


252  DYNAMICAL   GEOLOGY. 

ever,  as  Holland  states,  are  dean,  but  "now  and  then  one  is  seen  with 
bowlders  upon  it;  and  here  and  there  small  bergs  that  are  quite  covered 
with  stones  and  gravel"  (1877). 

Dr.  Kane,  describing  the  great  pack  of  icebergs  that  occupies  the  center 
of  Baffin  Bay,  mentions  that  some  were  300  feet  high,  and  large  numbers 
over  200  feet ;  280  of  the  first  magnitude  (the  most  of  them  over  250  feet) 
were  in  sight  at  one  time.  Taking  the  specific  gravity  of  iceberg-ice  at  0-886 
(Hell  and),  one  ninth  of  the  mass  by  weight  is  out  of  water.  In  the 
Antarctic,  the  long  ice-barrier  observed  by  Captain  Wilkes  had  a  height 
above  the  sea  of  150  to  200  feet ;  and  some  of  the  bergs  were  300  feet  high. 

(1)  Icebergs  are  a  means  of  transporting  stones  and  earth  from  one 
region  to  another;  and  those  of  Greenland  make  their  farthest  deposits  in 
the  Atlantic  about  the  banks  of  Newfoundland,  or  between  the  meridians  of 
of  44°  and  52°  and  north  of  the  parallel  'of  40°  30'. 

(2)  When  grounded  on  rocks,  they  may  scratch  the  surface ;  but  closely 
crowded  and  regular  scratches,  like  those  of  glaciers,  over  large  areas  cannot 
be  made.     An  iceberg  "  rocked  by  the  swell  of  the  sea,  and  sometimes  turn- 
ing over,"  could  not  be  good  at  scoring  submerged  rocks.     Moreover,  rocks 
over  the  sea-bottom  where  icebergs  drop  their  freight  of  stones  would  seldom 
be  uncovered. 


The  following  are  important  works  and  memoirs  on  existing  glaciers  :  — 

H.  B.  DE  SAUSSURE:    Voyage  dans  les  Alpes,  4  vols.,  1779-1796. 

AGASSIZ  :  Etudes  sur  les  Glaciers,  8vo,  Neuchatel,  1840.  —  Systeme  Glaciaire,  Nou- 
velles  Etudes  et  Experiences  sur  les  Glaciers  Actuels,  8vo,  with  an  Atlas  of  3  maps  and  9 
plates,  Paris,  1847. 

J.  DE  CHARPENTIER:  Essai  sur  les  Glaciers  et  sur  le  Terrain  Erratique  du  Bassin  du 
Rhone,  8vo,  Lausanne,  1841. 

J.  D.  FORBES  :  Travels  in  the  Alps  of  Savoy,  etc.,  8vo,  Edinburgh,  1843.  —  Occasional 
Papers  on  the  Theory  of  Glaciers,  8vo,  Edinburgh,  1859. 

J.  TYXDALL  :  The  Glaciers  of  the  Alps,  8vo,  London  (and  Boston),  1861. —  The 
Forms  of  Water  (in  Appleton's  International  Series),  8vo,  New  York,  1872. 

A.  HEIM  :  Handbuch  der  Gletscherkunde,  Stuttgart,  1885. 

N.  S.  SHALER  and  WILLIAM  M.  DAVIS:  Illustrations  of  the  Earth"1  s  Surface;  Glaciers, 
a  quarto  volume  containing  196  pages  of  text,  with  25  fine  plates  mostly  from  pho- 
tographs, 1881. 

The  following  relate  to  existing  glaciers  of  the  Pacific  Coast  of  North  America :  — 

DAVIDSON,  on  the  first  discovery  of  glaciers  on  the  Pacific  Coast  —  on  Mount  Rainier 
(Tacoma),  Mount  Baker:  Proc.  Acad.  California,  iv.  161,  1871,  and  Am.  Jour.  Sc.,  III., 
iv.  156,  1872. 

CLARENCE  KING:  "Glaciers  of  the  Pacific  Coast"  (on  Mount  Shasta,  Mount  Hood, 
Mount  Rainier,  etc.),  Am.  Jour.  Sc.,  III.,  i.  157,  1871,  and  "Report  40th  Parallel," 
vol.  i.  462,  1878. 

JOHN  MUIR  :  "Glaciers  in  California"  (Sierra  Nevada),  Overland  Monthly, 
December,  1872. 

JOSEPH  LE  CONTE  :  "  Ancient  Glaciers  of  the  Sierra  Nevada"  (with  notice  of  existing), 
Am.  Jour.  Sc.,  III.,  v.  325,  x.  156,  xviii.  43,  44. 

G.  F.  WRIGHT:   The  Ice  Age  in  North  America,  1889,  1891. 


HEAT.  253 

I.  C.  RUSSELL  :  Existing  Glaciers  in  the  United  States,  5th  Rep.  U.  S.  G.  S.  ;  "  Mount 
St.  Elias  Glaciers,"  Nat.  Geograph.  Mag.,  iii.,  1891,  and  Amer.  Jour.  Sc.,  1892. 

H.  P.  CUSHING  :  Notes  on  the  Muir  Glacier  region,  American  Geologist,  viii.  207,  1891. 
H.  F.  REID:  "Studies  of  Muir  Glacier,  Alaska,"  Nat.  Geograph.  Mag.,  iv.  19,  1892. 

V.   HEAT. 

The  sources  and  effects  of  heat  come  here  under  consideration.  The 
effects  are  those  connected  with  the  making  and  modifying  of  the  earth's 
rocks,  strata,  and  life,  exclusive  of  the  more  comprehensive  changes  result- 
ing from  the  earth's  gradual  refrigeration.  They  include  (a)  expansion  and 
contraction  ;  (b)  fusion,  solidification,  and  attending  igneous  phenomena ; 
(c)  metamorphism  and  vein-making,  besides  chemical  compositions,  decom- 
positions, and  other  effects.  After  some  observations  on  (I.)  the  Sources  of 
Heat,  these  subjects  are  considered  under  the  following  heads  :  (II.)  Expan- 
sion and  Contraction;  (III.)  Igneous  Action  and  Results ;  (IV.)  Metamor- 
phism ;  (V.)  Veins. 

The  effects  here  referred  to  are  mostly  due  to  heat  above  the  ordinary 
temperature.  But  some  geological  changes  of  the  widest  influence  have 
been  carried  forward  by  simple  changes  in  climate.  Hence  all  sources  of 
change  in  temperature,  however  slight,  have  a  geological  interest. 

I.  SOURCES  OF  HEAT  AND  THEIR  DIRECT  CLIMATAL  EFFECTS. 

THE  SUN  AS  A  SOUKCE  OF  HEAT. 

It  has  been  stated  that  the  heat  which  the  earth  receives  from  the  sun's 
rays  gives  it  a  temperature  300°  F.  above  that  which  it  would  have  in  cold 
sunless  space.  The  annual  amount  is  constant  through  all  orbital  changes, 
but  its  distribution  through  the  year  varies  with  these  changes. 

1.  Changes  connected  with  the  seasons.  — The  sun,  owing  to  the  obliquity 
between  the  earth's  equatorial  plane  (at  right  angles  to  the  axis  of  rotation) 
and  the  plane  of  the  ecliptic  (or  that  of  its  orbit)  gives  more  light  and  heat 
for  about  six  months,  between  the  vernal  and  autumnal  equinoxes,  to  the 
northern  hemisphere  than  to  the  southern,  making  thereby  a  northern 
summer  with  a  southern  winter ;  and  the  reverse  for  the  other  six  months. 
The  difference  in  the  heat  received  is  in  the  ratio  of  5  per  cent  for  the 
summer  interval  between  the  equinoxes  to  3  for  the  winter  interval. 

Further,  the  time  of  the  equinoxes,  or  that  of  the  sun's  crossing  of  the 
equator,  northward  and  southward,  is  slowly  changing  backward  in  the  series 
of  months,  and  in  less  than  six  centuries  the  vernal  equinox,  now  on  March 
21,  will  be  in  the  month  of  February  ;  thus  the  summer  months  after  a  while 
will  become  those  of  the  winter.  The  rate  of  the  precession  of  the  equi- 
noxes is  about  50-1  seconds  a  year,  or  a  degree  in  about  71-6  years,  which 
corresponds  nearly  to  a  month  in  2158  years,  and  a  complete  revolution  in 
25,868  years. 


254  DYNAMICAL    GEOLOGY. 

2.  Changes  in  the  time  of  the  perihelion  and  aphelion.  —  The  earth  is  now  in 
aphelion  during  the  northern  summer  and  southern  winter.     With  aphelion 
in  winter,  the  winters  are  colder  and  the  summers  are  warmer  than  with 
perihelion  in  winter.     The  position  of  the  major  axis  of  the  earth's  orbit 
(the  extremities  of  which  are  the  aphelion  and  perihelion  points)  is  chang- 
ing, and  a  complete  revolution  takes  110,000  years ;  and  since  this  change  is 
in  the  opposite  direction  from  that  of  the  precession  of  the  equinoxes,  above 
stated,  the  cycle  of  the  seasons   is   shortened   from   25,868   years  to  about 
21,000  years  ;  for,  supposing  the  perihelion  and  either  equinox  to  coincide, 
and  then  the  precession  to  move  in  its  direction  and  the  perihelion  in  the 
opposite,  at  their  respective  rates,  they  would  again  be  in  conjunction,  in 
consequence  of  these  rates,  in  21,000  years.      Hence,  every  10,500  years, 
the   seasons   become   reversed,   that   is,  the   months   of   winter  become   the 
summer    months.     Another   consequence   of    this   aphelion   cycle   is,   that 
the  winter  and  summer  intervals   between  the  equinoxes  vary  in  relative 
lengths,  the  aphelion  side  being  the  longer.     At  the  present  time  the  aphel- 
ion comes  in  summer,  and  the  summer  interval  is  therefore  seven  days  longer 
than  the  winter  interval. 

3.  Changes  in  the  eccentricity  of  the  earth's  orbit.  —  The  earth's  ellip- 
tical orbit  varies  slowly  in  eccentricity,  —  that  is,  in  the  length  of  its  major 
axis,  —  making  the  aphelion  distance  greater  and  the  perihelion  less,  but  not 
varying  the  mean  distance  or  the  amount  of  heat  received  annually  by  the 
earth  from  the  sun.     Maxima  in  the  eccentricity  occur  once  in  100,000  to 
200,000  years.     One  maximum  was  passed,  according  to  calculated  results, 
about  110,000  years  since;  another  (higher),  about  210,000  years  since;  the 
next  anterior  (like  the  latter  in  height),  about  750,000  years;  and  a  maxi- 
mum of  extreme  eccentricity,  850,000  years  since.     (Stock well,  1868.) 

With  the  sun's  mean  distance  92,400,000  miles,  the  present  aphelion  dis- 
tance is  about  93,950,000  miles,  and  the  perihelion,  90,850,000  miles,  and 
the  eccentricity,  0-0168.  But  at  the  time  of  extreme  maximum  eccentricity 
(=  0*075  nearly),  referred  to  above,  the  aphelion  distance  would  be  about 
99,300,000  miles,  and  the  perihelion  85,500,000,  making  the  sun  13£  millions 
of  miles  nearer  the  earth  in  summer  than  in  winter. 

Owing  to  the  increasing  eccentricity  there  is  an  increasing  difference  in 
the  length  of  the  winter  interval  as  compared  with  the  summer  interval; 
and  at  an  extreme  maximum  it  is  33  days  longer  than  the  summer  interval. 
As  the  amount  of  heat  which  the  earth  receives  varies  inversely  as  the 
square  of  the  sun's  distance,  increasing  eccentricity  diminishes  the  amount 
on  the  aphelion  side  and  increases  it  on  the  other ;  and  if  aphelion  comes  in 
winter,  the  winter  cold  is  greatly  augmented,  besides  continuing  longer. 
The  summers,  on  the  contrary,  would  be  proportionally  hotter,  but,  in  the 
same  proportion,  shorter.  With  aphelion  in  summer,  the  winters  would  be 
relatively  mild  and  the  summers  cool.  Herschel  first  drew  attention  to  this 
effect  of  extreme  eccentricity  (1858),  and  Croll  used  the  facts  in  his  Cli- 
mate and  Time  (1875)  to  account  for  the  occurrence  of  glacial  periods  in 


HEAT.  255 

the  earth's  history,  though  not  making  it  the  sole  cause  of  glacial  conditions, 
or  holding  that  such  conditions  would  necessarily  ensue.  The  heat  received 
during  the  summer  and  winter  intervals  being  as  5  to  3,  and  the  winter  inter- 
val 199  days  long  in  an  extreme  case,  the  severe  and  prolonged  cold  of  the 
winters  might,  other  things  favoring,  accumulate  more  snow  than  the  short 
summers  could  melt.  This  theory  makes  the  Glacial  period  of  the  northern 
hemisphere  follow  or  precede  that  of  the  southern  by  10,500  years  ;  that  is,  by 
half  of  a  revolution  of  the  seasons  (21,000  years).  Moreover,  the  condition 
of  maximum  eccentricity  is  so  slow  in  passing  that,  according  to  this  theory, 
two  or  more  glacial  periods  might  occur  in  the  course  of  one  maximum. 

This  subject  and  Croll's  theory  have  been  ably  discussed  in  a  volume  of  180  pages, 
entitled  The  Cause  of  an  Ice-Age,  by  the  Astronomer  Royal  of  Ireland,  Sir  Robert  Ball, 
1891.  The  conclusion  is  reached  that  the  conditions  of  a  period  of  maximum  eccentricity 
are  fully  adequate  to  cause  glacial  periods  in  geological  history.  See  also  a  notice  of  the 
work  by  G.  H.  Darwin  in  Nature  for  January  28,  1892. 

Geology  has  no  evidence  in  favor  of  the  idea  that  the  latest  of  Glacial  periods  occurred 
in  the  southern  hemisphere  10,500  years  after,  or  before,  the  northern,  and  it  has  prob- 
able evidence  that  the  time  of  the  Glacial  period  was  not  over  10,000  years  since,  and 
therefore  not  nearly  as  far  back  as  the  maximum  of  210,000  years  since,  or  that  of 
100,000.  Further,  it  has  discovered  no  satisfactory  traces  of  a  second  Glacial  period, 
corresponding  to  the  extreme  maximum  850,000  years  since  ;  for  it  has  good  proof  that  none 
occurred  between  the  Glacial  period  and  the  epoch  closing  the  Cretaceous  period,  some 
millions  of  years  since.  It  is  admitted,  however,  that  the  calculation  of  the  time  to  the 
extreme  maximum  (850,000  years)  is  not  wholly  trustworthy. 

4.  Progressing  diminution  in  the  sun's  heat.  —  Since  the  sun  has  been 
radiating  heat  through  all  past  ages,  the  earth  must  receive  less  heat  now 
than  in  Archaean  time ;  and  the  greater  heat  of  the  early  geological  ages  may 
have  this  as  a  chief  cause. 

5.  Changes  in  the  condition  of  the  sun's  surface. — The   changes   from 
maximum  to  minimum  in  the  spots  on  the  sun's  surface  have  a  cycle  of 
about  11  years,  the  minimum  occurring  in  the  year  1  of  the  century,  and 
the  year  1889  being  therefore  at  the  minimum.     How  far  this  cycle  is  one  of 
changing  temperature  to  the  earth  is  not  known.     Other  cyclical  changes  are 
possible,  and  are  conveniently  assumed  at  times,  though  not  proved. 

6.  Changes  in  the  position  of  the  earth's  axis  of  rotation.  —  Mathematical 
investigations  by  Lord  Kelvin  (Sir  William  Thomson),  S.  Haughton,  G.  H. 
Darwin,  and  others,  have  shown  this  hypothesis  to  be  of  no  geological  value. 
Darwin  has  demonstrated  that  a  displacement  of  the  pole  of  merely  1°  46' 
would  require  that  a  twentieth  of   the  whole    earth's    surface    should   be 
elevated  to  a  height  of   10,000   feet,   with  a  corresponding  subsidence  in 
another  quadrant ;  and  for  one  of  3°  17',  that  double  the  surface  should  have 
undergone  these  great  changes.     Kelvin  concludes  from  his  discussion  of  the 
subject  that  "there  is  no  evidence  in  geological  climate  throughout  those 
parts  of  the  world  which  geological  investigation  has  reached  to  give  any 
indication  of  the  poles  having  been  anywhere  but  where  they  are,  at  any 
period  of  geological  time." 


256  DYNAMICAL   GEOLOGY. 

7.  Variations  in  the  density  of  the  earth's  atmosphere.  —  The  atmosphere 
absorbs   and   retains   heat,   and    the   amount   absorbed   increases   with   its 
density.     In  early  geological  time,  the  earth's  atmosphere  contained  much 
more   carbonic   acid   and   moisture   than   now,    and   hence   it   would   have 
absorbed  more  of  the  sun's  rays  as  they  passed  through  it.     It  has  been 
shown  by  Tyndall  that  the  absorptive  power  of  carbonic  acid,  under  ordinary 
atmospheric  pressure,  is  90  times  greater  than  that  of  the  atmosphere,  and 
that  of  moisture  30  to  70   times    greater   for   non-luminous   heat.     Their 
presence  in  the  atmosphere  would  hence  have  greatly  increased  its  power  to 
absorb  and  retain  about  the  earth  the  sun's  heat.     "  They  would  produce 
little  reduction  in  the  amount  of  luminous  sun-heat  received,  and  would  be 
a  formidable  obstacle  to  non-luminous  heat  escaping  by  radiation  from,  the 
earth's  surface  into  the  cold  of  star-space  "  (Haughton,  1880). 

The  earth's  lower  plains  are  warmer  than  its  elevated  regions,  because  of 
the  greater  density  of  the  air.  The  lowest  places  should  thus  have  the 
warmest  climate ;  and  accordingly  the  basin  of  the  Dead  Sea,  1308  feet  below 
the  sea  level,  has  the  heat  of  the  torrid  zone. 

8.  Variations  in  oceanic  currents.  —  The  effect  of  the  Atlantic  tropical 
current  on  the  Arctic  and  north  Atlantic  climates  has  been  elucidated  by  the 
calculations  of  Mr.  James  Croll.     His  conclusion,  based  on  the  amount  of 
water  that  passes  the  Florida  Strait  (nearly  agreeing  with  the  latest  esti- 
mate), and  the  temperature  of  the  water,  is,  that  the  amount  of  heat  con- 
veyed from  the  equatorial  regions  northward  in  the  Atlantic  by  this  stream 
is  equivalent  to  77,479,650,000,000,000,000  foot-pounds  of  energy  per. day, 
which  is  equal  to  all  the  heat  received  by  1,560,935  square  miles  at  the 
equator,  and  more  heat  than  is  conveyed  by  all  the  aerial  currents;  and 
that  the  stoppage  or  diversion  of  the  current  would  diminish  to  this  extent 
the  heat  of  the  Arctic  seas  and  north  Atlantic. 

It  has  been  supposed  that  the  diversion  of  the  Gulf  Stream  from  the 
north  Atlantic  may  have  taken  place  through  the  sinking  of  the  region  of 
the  Isthmus  of  Darien ;  but  there  is  no  sufficient  evidence  that  such  a  diver- 
sion has  happened  since  Mesozoic  time.  A  more  reasonable  hypothesis  is 
that  it  may  have  been  accomplished  by  a  raising  of  the  sea-bottom  nearly 
to  the  surface  between  Scandinavia,  Great  Britain,  Iceland,  and  Greenland, 
where  the  depth  now  is  mostly  less  than  100  fathoms  and  nowhere  exceeds 
1000,  and  along  one  tract  is  not  over  500  fathoms.  The  effect  of  such  a 
north  Atlantic  barrier  would  be  to  confine  the  Atlantic  tropical  current  to 
the  north  Atlantic,  and  thereby  to  increase  the  temperature  and  amount 
of  evaporation  of  that  ocean.  It  would  reduce  the  northern  part  of  the 
stream  to  the  southeast  branch,  and  might  diminish  its  volume;  but,  in 
view  of  the  form  of  the  south  Atlantic  depression  and  its  position  with 
reference  to  the  north  Atlantic,  the  warm  stream  could  not  fail  to  continue 
its  flow. 

Again,  the  Arctic  region  may  formerly  have  had  its  climate  moderated 
by  receiving  the  Pacific  tropical  current,  through  a  submergence  about 


HEAT.  257 

Bering  Strait  —  now  only  150  feet  deep ;  and  if  so,  this  current,  upon  the 
opening  of  the  deep  passage  for  discharge  northward,  would  have  been  aug- 
mented in  its  size  and  its  heating  influence. 


THE  EARTH'S  INTERIOR  AS  A  SOURCE  OF  HEAT. 

Diminution  in  the  heat  reaching  the  surf  ace  from  the  earth's  interior.  —  The 
proofs  of  the  existence  of  a  source  of  heat  within  the  earth  are  the  fol- 
lowing :  — 

1.  Borings  for  Artesian  wells  and  shafts  in  mines  have  afforded  a  means 
of  taking  the  temperature  of  the  earth  at  different  depths.  It  has  thus 
been  found  that,  after  passing  the  limit  of  surface  action,  the  heat  increases 
downward,  but  at  a  varying  rate.  The  common  rate  within  4000  feet  of 
the  surface  is  55  to  60  feet  for  1°  F.,  or  the  mean  571  feet ;  or  in  geother- 
mometric  language,  57^  feet  corresponds  to  1  geothermic  degree.  At  Speren- 
berg,  near  Berlin,  large  variations  were  obtained  in  a  well  4172  feet  deep ;  but 
it  went  down  through  a  stratum  of  salt,  excepting  the  upper  300  feet ;  at 
bottom,  the  temperature  was  118-6°  F. 

At  the  Artesian  well  of  Grenelle,  Paris,  a  temperature  of  85°  F.  was 
obtained  at  2000  feet,  equivalent  to  1°  F.  for  every  60  feet.  In  Westphalia, 
at  Neusalzwerk,  in  a  well  2200  feet  deep,  the  temperature  at  the  bottom  was 
91°  F.,  or  1°  F.  for  50  feet  of  descent.  At  Yakutsk,  Siberia,  Magnus  found 
a  gain  of  15°  F.  in  descending  407  feet,  equal  to  1°  F.  for  27  feet.  In  Algiers, 
an  increase  of  1°  in  42  feet  has  been  observed ;  and  in  the  Sahara  1°  in  32 
feet.  In  Great  Britain  the  mean  is  1°  F.  for  51^  feet. 

At  Schladenbach,  in  Prussia,  at  a  depth  of  5735  feet,  the  temperature 
134°  F.  was  obtained  ;  and  at  Pesth,  Hungary,  at  3120  feet  a  boring  supplied 
daily  176,000  gallons  of  water  at  158°  F.  The  municipality  were  carrying  it 
down  in  order  to  reach  176°  F.  (80°  C.)  for  the  brewers. 

A  boring  at  Wheeling,  W.  Va.,  to  a  depth  of  4500  feet  (in  1892),  3700 
feet  below  the  sea  level,  through  nearly  horizontal  rocks,  shows  a  mean  rate 
of  increase  for  the  upper  half  of  1°  F.  for  80  feet,  and  in  the  lower  half  of  1° 
F.  for  60  feet.  For  great  depths  the  ratio  is  not  an  arithmetical  one,  because 
of  the  greater  conductivity  of  the  earth  below  (owing  to  greater  density) 
and  the  augmented  pressure.  But  nothing  is  yet  known  as  to  the  rate  of 
increase  downward,  or  the  number  of  feet  to  a  geothermic  degree. 

Doubts  with  regard  to  the  observations  on  the  increase  of  heat  downward 
in  borings,  and  in  shafts  in  mines,  come  from  the  facts  that  chemical  action, 
and,  prominently,  the  oxidation  of  pyrite  and  other  sulphides,  is  a  source  of 
heat ;  and  this  has  always  to  be  considered  in  such  investigations.  Besides, 
local  sources  of  subterranean  heat  may  exist.  At  the  Comstock  lode,  in 
Nevada.,  the  temperature  of  the  mine  in  some  parts,  at  a  depth  of  1800  to 
2000  feet,  is  130°  to  157°  F.,  and,  when  mining  was  there  in  progress,  over  30 
tons  of  ice  per  day  were  expended  in  keeping  the  air  cool  enough  for  the 
DANA'S  MANUAL — 17 


258  DYNAMICAL   GEOLOGY. 

endurance  of  the  miners.  The  heat  in  this  case  was  of  local  origin,  as  the 
region  is  one  of  former  igneous  eruptions. 

2.  The  wide  distribution  of  volcanoes  over  the  globe  affords  evidence  of 
internal  heat.  Moreover,  the  ejection  of  melted  rock  through  fissures  has 
taken  place  over  all  the  continents ;  in  Nova  Scotia,  Canada,  New  England, 
New  Jersey,  and  the  states  south,  the  region  of  Lake  Superior,  the  Rocky 
Mountains,  and  western  America;  in  Ireland,  Scotland,  and  various  parts 
of  Europe ;  and  so  over  much  of  the  globe.  Such  facts  favor  the  idea  of  an 
internal  source  of  heat.  The  heat  of  the  earth's  interior  has  reached  toward 
or  to  the  surface  for  geological  work  in  three  ways. 

(a)  By  conduction  outward  attending  the  earth's  cooling.  —  The  amount 
thus  received  at  the  surface  may  have  been  sufficient  to  modify  somewhat 
the  temperature  of  the  oceans,  and  the  earth's  climates,  during  early  geo- 
logical time.  At  present  it  is  inappreciable ;  and  yet,  according  to  Kelvin, 
the  amount  of  heat  now  lost  by  the  earth,  as  a  consequence  of  cooling,  is  such 
as  would  melt  annually  a  complete  covering  of  ice  0*0085  millimeter  thick,  to 
water  at  32°  F.,  or  bring  777  cubic  miles  of  ice  to  the  same  state. 

(6)  By  fractures  of  the  crust,  and  the  escape  of  melted  rock  or  hot  vapors. 

(c)  By  an  accumulation  of  sedimentary  deposits  over  large  regions.  —  It  fol- 
lows from  the  conditions  of  a  globe  having  an  internal  source  of  heat,  that 
equal  temperatures  will  exist,  as  a  general  thing,  at  equal  depths ;  in  other 
words,  that  isothermal  planes,  or  more  precisely,  isogeothermal,  will  be  par- 
allel to  the  surface  ;  and  that  they  will  even  bend  upward  to  correspond  with 
the  general  curve  of  the  broader  mountain  regions,  and  downward  beneath 
the  oceanic  depressions.  Consequently,  the  isogeothermal  planes  will  rise  a 
thousand  feet  for  every  thousand  feet  in  depth  of  deposits  spread  out  over 
a  wide  area;  and,  as  urged  by  Babbage,  solidification,  crystallization,  and 
other  chemical  changes  may  thus  be  occasioned  in  the  inferior  beds,  provided 
the  accumulation  reaches  a  depth  adequate  to  raise  upward  the  requisite 
amount  of  heat. 

Again,  the  removal  of  rock-material  from  wide  areas,  as  is  done  in  the 
slow  processes  of  erosion,  will  tend  to  produce  an  equivalent  depression  of 
the  isogeothermal  planes. 

CHEMICAL  AND  PHYSICAL  CHANGES  AND  MECHANICAL  ACTION  AS 

SOURCES  OF  HEAT. 

Heat  is  evolved  by  chemical  changes  in  which  there  is  condensation,  as  in 
liquids  becoming  solids,  or  gases  becoming  liquids,  and  in  oxidation,  etc.  It 
is  often  an  effect  of  the  natural  decomposition  of  minerals,  or  vegetable  or 
animal  matter.  The  oxidation  of  sulphides,  and  especially  of  the  most  com- 
mon of  them,  pyrite  and  marcasite,  is  a  source  of  heat  in  many  mines,  and 
for  many  warm  springs.  In  the  formation  of  a  pound  of  water  from  vapor, 
heat  enough  is  given  out,  says  Tyndall,  to  melt  five  pounds  of  cast  iron. 

The  heat  of  lightning  has  also  its  effects  among  geological  phenomena. 


HEAT.  259 

Electric  currents  have  long  been  suspected  of  various  results  of  other  kinds, 
but  little  has  yet  been  directly  traced  to  their  action,  except  such  as  come 
under  the  general  head  of  chemical  effects. 

Under  examples  of  mechanical  action,  there  are  the  beating  of  waves  on 
a  coast,  the  falling  of  water  in  cascades  or  rain,  the  shakings  of  earthquakes, 
the  sliding  of  rocks,  the  motion  of  the  atmosphere  in  winds,  each  of  which 
produces  heat  whenever  the  action  meets  with  resistance,  on  the  principle 
that  motion  corresponds  to  an  amount  of  heat,  or  that  heat  is  transformed 
motion.  The  heat  thus  resulting  is,  however,  of  little  geological  importance. 
But  the  friction  attending  uplifting,  plicating,  shoving  along  fractures,  and 
crushing  of  rocks  has  often  been  an  efficient  and  wide-reaching  source  of 
heat  and  of  geological  work.  These  shovings  have  flexed  strata  many  thou- 
sands of  feet  in  thickness,  made  displacements  along  fractures  of  10,000  to 
20,000  feet,  and  worked  in  this  way  over  areas  more  than  1000  miles  long 
and  some  hundreds  in  width.  The  amount  of  heat  developed  has  therefore 
been  enormous ;  but  how  far  available  for  geological  changes  would  depend 
in  part  011  the  rate  at  which  such  work  went  forward.  It  has  been  sufficient, 
beyond  question,  for  a  large  amount  of  consolidations,  and  for  recrystalliza- 
tions  or  metamorphism  on  a  large  scale,  and  it  has  probably  been  sufficient 
for  much  fusion  of  rocks  in  the  earth's  interior  wherever  the  temperature  was 
on  the  margin  of  fusion. 

Mallet  concluded,  from  his  calculations,  that  7200  cubic  miles  of  crushed  rock  would 
cause  heat  enough  to  make  all  the  volcanic  mountains  of  the  globe ;  and  that,  since  the 
ejections  of  volcanoes  have  been  going  forward  through  a  very  long  period,  the  action 
would  require  but  an  infinitesimal  amount  of  annual  crushing  —  not  over  0-606  of  a  cubic 
mile.  (Trans.  Roy.  Soc.,  1872.)  But  his  theory  is  accepted  only  in  a  general  way. 

II.   EXPANSION   AND   CONTRACTION. 

1.  Amount  of  expansion.  —  The  amount  of  expansion  of  rocks  is  mostly 
between  1  and  10  millionths  for  1°  F. ;  and  one  millionth  corresponds  to  1-2 
thousandths  of  an  inch  for  100  feet.     Colonel  Totten,  in  experiments,  made 
in  1830  to  1833,  on  effects  of  change  of  temperature,  found  that  an  inch  of 
fine-grained  granite  expands  for  1°  F.,  0*000004825 ;  an  inch  of  the  granular 
limestone  of  Sing  Sing,  N.Y.,  0-000005668 ;  of  red  sandstone,  from  Portland, 
Conn.,  0-000009632.     Adie  (Trans.  R.  Soc.,  Edinburgh,  xiii.,  and  Q.  J.  G.  Soc., 
1847)  found  for  the  expansion  of  gray  Aberdeen  granite  for  1°  F.,  0-00000438 ; 
for  white  marble  of  Sicily,  0-00000613.     Pfaff  found  for  the  expansion  be- 
tween the  ordinary  temperature  and  red  heat  (about  1750°  F.)  of  granite 
from  the  Fichtelgebirge,  0-0168 ;  for  porphyry  from  the  Tyrol,  0-0127 ;  and 
for  basalt  of  Auvergne,  0-0120. 

2.  Effects  of  changes  in  temperature  due  to  the  sun,  or  the  climate.  —  (a)  The 
sun  is  producing  somewhere,  at  all  times,  alternations  of  temperature,  and 
thereby  change  of  size  and  position  ;  and  the  same  effect  comes  from  changes 
of  temperature,,  whatever  the  source.     The  cause  is  universal  in  its  action. 


260  DYNAMICAL   GEOLOGY. 

With,  the  progress  of  the  sun  during  a  sunny  day  Bunker  Hill  Monument,  a 
hollow  obelisk,  221  feet  high  and  30  feet  square  at  base  (made  of  granite 
blocks),  swings  to  one  side  and  the  other,  a  pendulum  suspended  from  the 
center  of  the  top  describing  an  irregular  ellipse  nearly  half  an  inch  in  its 
greatest  diameter  (Horsford).  Such  a  cause,  working  day  after  day  about 
rocky  peaks  and  precipices,  causing  each  day  some  displacement,  must  end 
in  degradations  of  geological  importance. 

(b)  Expansion  works  with  special  facility  if  blocks  rest  on  an  inclined  sur- 
face, even  when  the  inclination  is  very  small.     It  extends  the  mass  down 
the  slope, — the  direction  of  easiest  movement,  —  and  contraction  pulls  the 
mass  to  the  expansion  line  for  the  same  reason ;  and  thus  masses  slide  on 
till  they  fall  over  precipices,  or  off  cliffs  into  the  sea.     Even  the  loose  stones 
or  blocks  of  a  talus  are  kept  on  a  downward  move  by  the  same  means.     The 
action  of  frost  has  already  been  mentioned  (page  231)  as  another  one  of  the 
causes  of  a  slipping  movement  in  rocks  and  soil. 

(c)  Expansion  and  contraction  also  cause  grains  and  thin  portions  of  the 
exterior  of  rocks  to  peel  off  or  crack  away  from  the  part  below.     It  hence 
may  open  fractures  and  so  give  access  to  air  and  moisture  for  other  destruc- 
tive work. 

Further :  terranes  of  granite,  granitoid  gneiss,  syenyte,  and  other  mas- 
sive rocks,  as  in  the  domes  about  the  Yosemite  in  California,  are  often  divided 
into  parallel  concentric  or  horizontal  layers  a  foot  to  a  yard  and  more  thick; 
and  vertical  joints  at  irregular  intervals  also  are  made.  J.  D.  Whitney 
states  that  the  dome-like  shapes  of  the  Yosemite  summits  are  thus  made ;  for 
"the  curves  are  arranged  strictly  with  reference  to  the  surface  of  the  masses" 
(1865).  These  effects  have  been  attributed  to  contraction  attending  the 
original  cooling;  but  also  to  the  climatal  heat  through  daily  and  sea- 
sonal cooling. 

On  some  of  the  Thimble  Islands,  off  the  shores  of  Stony  Creek,  Conn.,  the  walls  of 
granitoid  gneiss  facing  the  water  are  peeling  off  in  laminae  a  third  to  a  half  inch  thick, 
without  any  apparent  decomposition,  or  even  a  dimming  of  the  luster  of  the  feldspar  or 
mica ;  and  it  may  be  owing  to  the  heat  of  the  day's  sun,  and  the  chilling  by  the  waters 
when  the  tide  is  in.  In  the  same  region  the  slipping  of  great  masses  of  rocks  from  the 
islands  into  the  salt  water  is  well  exemplified. 

Over  the  rocky  surface  of  countries  within  the  glacial  latitudes  of  the  Glacial  period, 
the  scratches  left  by  the  glacier  are  generally,  when  first  uncovered,  as  fresh  as  when  they 
were  made.  But,  if  the  surface  be  open  to  the  sun's  heat  and  light,  and  to  the  rains  and 
frosts,  for  a  score  of  years,  far  the  larger  part  of  the  markings  disappear ;  and  alternate 
heating  and  cooling  is  an  important  means  of  this  obliteration. 

(d)  By  drying,  the  sun's  heat  produces  cracks,  the  lightest  cases  of  which 
are  mud-cracks  (page  94).     Such  cracks  in  mud  or  earth,  and  therefore  in 
rocks,  are  shallow,  and  by  this  means  they  may  be  distinguished  from  cracks 
or  fissures  made  by  other  means. 

3.  Effects  of  heat  from  interior  sources.  —  From  Totten's  experiments  as 
data,  Lyell  has  calculated  that  a  mass  of  sandstone  a  mile  thick,  raised  in 


HEAT. 


261 


217. 


temperature  200°  F.,  would  have  its  upper  surface  elevated  10  feet ;  and  that 
a  portion  of  the  earth's  crust  50  miles  thick,  raised  600°  F.  to  800°  F.,  might 
become  elevated  1000  to  1500  feet.  Cooling  would  tend  to  reverse  the  result. 

(a)  Contraction  from  cooling  in  case  of  fusion  general!}'  produces  fractures 
at  right  angles  to  the  cooling  surfaces ;  and  in  this  way,  "basaltic"  columns 
have  been  produced.  Besides  such  transverse  fractures,  there  frequently 
exist  longitudinal  fractures  along  the  middle  or  sides  of  dikes  due  to  trans- 
verse contraction ;  and  transverse  fractures  of 
columns  are  very  common. 

One  of  the  most  noted  localities  of  "basaltic 
columns  "  is  that  of  the  Giant's  Causeway  on 
the  northern  coast  of  Ireland.  The  columns 
(Fig.  217)  are  divided  transversely  and  have 
usually  the  upper  surface  of  each  section 
slightly  concave.  In  the  columnar  structure 
the  form  is  often  six-sided,  but  five  to  nine 
sides  are  common,  owing  to  irregularities  of 
texture  and  cooling. 

Fig.  218  represents  a  scene  from  the  coast  of  Illawarra,  in  southeastern 
Australia,  in  which  there  are  columns  of  two  outflows,  the  nearer  less  per- 

218. 


Giant's  Causeway. 


Basaltic  columns,  at  Kiama,  on  the  coast  of  Illawarra,  New  South  Wales.     D.,  Note-Book,  '39. 

feet  in  form  resting  on  horizontal  stratified  rocks,  the  other  a  larger  outflow 
in  regular  vertical  columns  five  to  eight  feet  in  diameter. 


262 


DYNAMICAL   GEOLOGY. 


The  vertical  position  shows  that  the  cooling  surfaces  were  (1)  the  rocks 
underneath  and  (2)  the  air  above ;  and  the  regularity  of  position  indicates 
remarkably  equable  progress  through  the  mass  in  the  cooling.  Fig.  219, 
representing  a  dike  and  overflow  from  the  same  region,  shows  the  effects 
of  position  in  cooling  surfaces ;  the  dike,  with  vertical  walls  having  horizon- 
tal columns,  and  the  overflow,  vertical  columns.  The  rock  intersected  and 
overlaid  is  a  conglomerate,  and  part  of  the  latter  is  involved  in  the  basalt. 


219. 


220. 


Dike  with  outflow,  Kiama.    D. 


Curved  columns,  Kiama.    D.  '49. 


The  effect  of  a  small  ridge  (of  conglomerate)  in  making  curved  columns 
is  shown  in  Fig.  220.  For  a  short  distance  the  basalt  is  massive ;  then  the 
columns  —  one  to  four  feet  in  diameter  and  30  long  —  begin  abruptly.  The 
low  terminal  plane  of  the  column  is  flat ;  but  this  plane  is  nearly  horizontal 
tvhatever  the  obliquity  of  the  prism,  the  variation  from  it  where  greatest  not 
exceeding  20°.  The  stream  of  basalt  was  50  feet  thick. 

221. 


Columnar  Basalt,  Orange,  N.J.    Iddings,  '86. 


The  trap  of  the  Triassic  of  eastern  North  America  is  usually  more  or 
less  columnar ;  and  in  some  places  regularly  so.  At  a  quarry  in  Orange, 
N.J.,.  west  of-  the  city,  the  columns  are  in  groups  which  are  in  some  parts 


HEAT. 


263 


abruptly  diverse  in  positions  and  size,  as  shown  above.  The  diameters 
vary  from  four  feet  to  six  or  eight  inches;  and  some  groups  are  much  curved. 
Iddings  refers  the  abrupt  changes  to  irregular  cooling  after  the  surface  had 
crusted  over,  different  rates  proceeding  from  the  lower  and  upper  surfaces. 
To  this  may  be  added  that  the  upward  flow  or  thrust  of  the  liquid  rock 
was  probably  more  or  less  intermittent,  as  it  is  a  common  fact  in  modern 
flows  about  volcanoes. 

Basaltic  rocks  are  much  more  generally  columnar  than  other  kinds  of 
igneous  rocks.     Figs.  222  and  224  show  the  same  structure  in  phonolyte, 


222. 


The  Phonolyte  Peak,  1000  feet  high,  on  Fernando  de  Noronha.    J.  C.  Branner,  '89. 

and  in  half-stony  volcanic  glass.  The  first,  representing  a  peak,  1000 
feet  high,  on  the  island  of  Fernando  de  Noronha,  is  from  a  paper  by 
J.  C.  Branner.  The  second  shows  the  well-developed  columns  of  "  Obsidian 
Cliff"  (a  noted  locality  in  the  Yellowstone  Park).  The  columns  are  50  to 
60  feet  high ;  above  the  columns  for  50  feet,  or  so,  the  obsidian  is  massive. 
(Iddings,  1886.)  The  cross-lining  in  the  figure  represents  shading  and  not 
the  thin  laminated  structure  that  characterizes  much  of  the  obsidian. 

In  a  cooling  layer  of  fused  rock,  the  smallest  number  of  fractures  that 


264 


DYNAMICAL   GEOLOGY. 


224. 


can  be  opened  about  a  point  on  its  surface  by  equable  contraction  is  three, 
223         and  hence  this  number  is  the  easiest  to  make;  and  since  three 
such  lines  symmetrically  placed  make  angles  with  one  another 
of  120°  (Fig.  223),  the  hexagonal  prism,  more  or  less  regular,  is 
the  most  common  form  of  the  "  basaltic  "  column. 

In  the  case  of  large  dikes  between  walls  of  rock,  the  set  of 
divisional  planes  which  is  nearly  or  quite  vertical  is  generally  more  strongly 
developed  than  the  others,  and  this  occasions  a  laminated  structure  in  that 

direction  looking  like 
upturned  bedding. 
This  structure  is  com- 
mon in  the  trap  of  the 
Triassic  of  the  Con- 
necticut valley ;  and  at 
the  same  time  joints 
transverse  to  the  ap- 
parent lamination  also 
occur.  In  many  of  the 
nearly  vertical  fronts, 
these  two  courses  of 
joints  are  predominant. 
(6)  Contraction  from 
cooling  when  the  heat  is 
short  of  fusion  often 
produces  columnar 
fractures  in  fine- 
grained rocks.  Sand- 
stones are  thus  made 
columnar  by  contact 
with  melted  rocks. 
Part  of  the  effect  is 
due  to  drying. 

4.  Expansion  and 
contraction  in  the  pro- 
cess of  solidification 
and  fusion.  —  Since  the 
glass  state  of  a  mineral 
or  rock  is  a  conse- 
quence of  rapid  cool- 
ing from  fusion,  and 
the  stone  state  is  the 
result  of  slow  cooling, 

Obsidian  columns,  Yellowstone  Park.    Iddings.  gl^SS  will  become  Stone 

if    melted    and     very 
slowly  cooled.     In  passing  from  the  liquid  to  the  glass  state,  in  the  case  of 


HEAT.  265 

plate  glass,  at  the  Thames  Glass  Works,  the  contraction  was  1-59  per  cent, — 
100  parts,  by  weight,  becoming  9841  (Mallet).  In  passing  from  the  stone 
to  the  glass  state,  according  to  Delesse,  granite  decreases  in  density  9  to  11 
per  cent ;  syenyte,  8  to  9 ;  dioryte,  6  to  8 ;  doleryte,  5  to  7 ;  trachyte,  3  to  5 
per  cent.  Cast  iron  loses  in  density  on  heating,  and  also  on  solidifying; 
trials  gave  a  density  of  7*214  when  cold,  6*535  before  fusion,  and  6*883  when 
liquid  (Hannay). 

III.    IGNEOUS  ACTION  AND   ITS  RESULTS. 

Igneous  action  has  its  origin  almost  exclusively  within  the  earth's  heated 
interior.  A  few  phenomena  only  are  due  to  exterior  agencies.  Its  chief 
direct  results  include :  (1)  the  melting  of  rocks ;  (2)  the  eruption  of  melted 
or  plastic  rock  from  some  subterranean  source  into  or  through  fissures  or 
spaces  opened  in  the  earth's  crust,  —  thus  making  eruptive  rocks ;  (3)  the 
repeated  eruption  of  melted  rock,  through  long  periods,  from  local  vents,  — 
thereby  making  volcanoes;  (4)  the  imbibing  by  the  melted  rock,  while  on 
its  way  up,  of  vapors  generated  from  ingredients  encountered  in  the  adjoin- 
ing rocks,  and  especially  of  water-vapor,  derived  from  the  moisture  of  these 
rocks  and  from  subterranean  streams,  —  producing,  in  the  melted  rock,  aug- 
mented mechanical  and  chemical  powers ;  (5)  the  communication  of  heat 
and  vapors  to  the  adjoining  rocks,  —  producing  in  these  outside  rocks  chemi- 
cal and  physical  changes.  Earthquakes,  solfataras,  fumaroles,  hot  springs, 
geysers,  and  also  mineral  depositions  and  emanations  in  connection  with  the 
hot  springs  and  fumaroles,  are  among  the  attendant  results. 

In  the  following  pages  the  results  of  exterior  agencies  are  first  presented ; 
and  then  those  of  interior  origin,  under  the  heads  of  Volcanoes,  Non-volcanic 
Igneous  Eruptions,  and  Geysers. 

ACTION  OF  EXTERIOR  AGENCIES. 

Lightning,  an  electric  discharge  or  a  combination  of  them,  occasionally 
leaves  evidence  of  its  intense  heat  on  rocks  and  sand-heaps,  by  the 
fusion  of  the  constituent  minerals  into  a  tube  around  its  pathway,  or  in 
patches  of  glassy  beads.  The  tubes,  called  fulgurites,  have  been  observed 
in  many  places  in  the  sands  of  dunes,  descending  to  a  depth  of  one  to  three 
feet ;  and  one  of  ten  feet  is  reported.  They  are  one  half  to  two  or  more 
inches  across,  often  contorted,  taper,  and  sometimes  branch,  downward. 
Tubes  two  feet  long,  found  near  Pensacola,  Fla.,  consisted  within  of  a 
bright  clear  glass  almost  free  from  grains  of  quartz  (Diller,  1884).  A 
fulgurite  from  the  sand  near  Waterville,  Me.,  has  been  described  by  W.  S. 
Bayley  (1872).  The  fulgurites  in  rocks  occur  especially  about  the  summits 
of  mountains.  They  have  been  observed  in  Mexico  in  the  trachytic  summit 
of  Toluca  (Humboldt);  in  Little  Ararat,  Caucasus,  in  augite-andesyte 
(Abich);  on  the  top  of  Mont  Blanc  and  at  a  dozen  other  points  in  the  Alps ; 
at  many  places  in  the  Pyrenees ;  also  in  Oregon  and  Colorado. 


266  DYNAMICAL   GEOLOGY. 

The  common  effects  on  the  rocks  are :  the  covering  of  small  surface  spots, 
or  depressions,  with  beads  of  glass,  or  with  sinuous  glassy  lines  sometimes 
radiating ;  the  production  of  tubes  sometimes  half  an  inch  or  more  in 
diameter,  descending  with  diminishing  size  a  few  inches  into  the  rock,  and 
sometimes  dividing  downward ;  the  glass  being  such  as  the  rock,  or  some  of 
its  more  fusible  ingredients,  would  afford  on  fusion.  The  usual  absence  of 
microlites  is  regarded  as  an  indication  of  the  sudden  cooling  of  the  glass. 

Specimens  from  Mount  Thielson,  Oregon,  south  of  the  Columbia,  where  the  rock  is 
hypersthene-basalt,  consist,  according  to  Diller,  of  a  coating  of  patches  and  beads  of 
glass,  and  also  of  tubes  ^  to  f  inch  in  diameter,  having  a  brownish  glass  within,  which 
descend  2  to  3  inches  into  the  rock.  On  West  Peak,  east  of  the  Sangre  de  Cristo  Range, 
Col.,  tubes  glassy  within,  and  surface-depressions  with  beads  of  glass,  occur  in  augite- 
dioryte,  and  in  one  place  a  tube  appeared  to  follow  the  course  of  a  small  vein  of  ore 
(R.  C.  Hills,  1890).  A  fulgurite-glass,  occurring  in  the  Alps  on  Mount  Viso,  coating  fur- 
rows made  in  glaucophane  schist,  was  peculiar  in  containing  microlites  (Rutley,  1889). 

The  disrupting  power  of  lightning  is  sometimes  shown  in  the  fracturing  of  rocks,  and 
it  is  supposed  that  this  may  have  been,  in  past  time,  an  important  agent  of  rock-destruc- 
tion. But  this  theory  is  opposed  by  the  fact  that  the  strokes  producing  fulgurites  have 
done  very  little  shattering. 

225. 


Vesuvius  as  seen  from  the  harbor  of  Naples.    D.  July,  '34. 

The  burning  of  coal-beds  has  produced  scoria  and  other  igneous  results  in  North  Dakota 
and  Montana.  But  the  mode  of  ignition  of  the  beds  is  not  known.  A  stroke  of  lightning 
is  the  most  probable  agent.  It  is  hardly  possible  that  chemical  changes  ever  occasioned 
it.  In  the  States  above  mentioned  the  burning  of  coal-beds  of  the  Lignitic  Tertiary  has 
changed  clays  to  hard  and  sometimes  porcelain-like  rocks,  usually  reddening  them,  and 
also  to  beds  of  a  half-fused  cellular  or  scoriaceous  and  pumice-like  character,  looking  like 
the  products  of  a  volcano.  One  of  the  regions  thus  burnt  over,  on  the  Little  Missouri, 
is  20  to  30  miles  broad  by  200  miles  in  length.  Others  occur  in  the  Yellowstone  at  the 
mouth  of  Powder  River  and  along  the  latter  stream  ;  about  the  sources  of  Tongue  River, 
within  a  few  miles  of  the  Big  Horn  Mountains,  and  on  the  north  fork  of  the  Cheyenne 
River,  as  observed  by  Hayden.  Fragments  of  pumice  have  been  found  on  the  Missouri 
as  far  south  as  Pierre,  and  the  early  explorers  supposed  them  to  be  the  products  of 


HEAT. 


267 


unknown  volcanoes,  high  up  in  the  mountains.  The  baked  rocks,  besides  giving  their  red 
tints  to  the  country,  resist  erosion,  as  Mr.  Allen  states  (1874),  and  so  protect  the  hills 
from  denudation,  and  become  prominent  features  of  the  region. 


VOLCANOES. 

1.  General  Characteristics. 

An  active  volcano,  as  ordinarily  understood,  is  a  mountain  or  hill  more 
or  less  conical  in  shape,  having  at  or  near  its  top  a  cavity  called  a  crater ; 
and,  within  the  crater,  a  vent  or  source  of  liquid  rock  and  hot  vapors,  whence 
proceed  at  times  ejections  of  lava  in  streams,  or  else  in  projected  fragments. 
It  is  fundamentally  a  vent  of  vapors  and  liquid  rock,  which,  by  its  projectile 
action  has  been  and  is  still  surrounding  itself  by  an  elevation  of  more  or  less 

226. 


Mount  Shasta  as  seen  from  the  south.     Height,  14,401  feet.     From  a  photograph  by  Watkins. 

conical  form  and  pericentric  structure.  The  ejected  materials  descend  around 
the  vent,  and  by  this  pericentric  work  build  up  the  rising  volcanic  cone. 
The  liquid  rock  and  its  cooled  streams  are  the  lava  of  the  volcano,  and 
the  loftily  projected  lava-fragments,  cooled  as  they  fall,  which  may  be  for 
years  the  only  ejected  material,  are  the  cinders  (lapilli  of  the  Italians),  or 
volcanic  ashes  when  fine,  or  volcanic  scoria  when  made  up  of  light  cellular 
pieces. 

A  view  of  Vesuvius  as  it  appeared  in  July,  1834,  is  given  in  Figure  225. 
The  main  body  of  the  mountain  is  made  of  lava  streams,  with  some  layers 


268 


DYNAMICAL   GEOLOGY. 


of  cinders;  the  large  active  cone  to  the  right  consists  outside  and  at  the 
top  of  cinders ;  and  the  small  cone  at  the  very  top  giving  out  vapors,  of 
cinders  alone.  The  whole  height  is  nearly  4000  feet. 


227. 


HAWAII 

FROM  THE 

GOVERNMENT  MAP 


If  the  projected  fragments  of  lava  are  thrown  only  to  a  small  height,  as 
is  usual  at  the  volcanoes  of  Hawaii,  they  descend  without  cooling  and 
adhere  to  the  surface  on  which  they  fall,  where  they  have  the  appearance 
of  cooled  drops,  driblets,  or  incipient  streamlets  of  lava. 

The  vapor  escaping  from  the  crater,  often  wrongly  called  smoke,  is  chiefly 
vapor  of  water,  with  quantities  of  other  vapors  or  gases. 


HEAT. 


269 


Lava-cones,  Cinder-cones,  Tufa-cones,  Driblet-cones.  —  An  active  volcano 
may  have  discharges  of  lavas ;  or  discharges  of  projected  fragments,  that  is 
projectile  discharges ;  or  discharges,  for  long  periods,  of  vapors  alone. 

Outflowing  lavas  make  a  lava-cone,  which  may  vary  in  angle  of  slope 
from  3°  to  25°  or  more.  Mount  Shasta  (Fig.  226),  in  northern  California, 
is  one  of  the  steeper  cones,  and  those  of  Hawaii  are  cones  of  low  angle. 

228. 


S.E.    A 


B • =— C    N.  W. 

A,  B,  B,  C,  profile  of  Hawaii,  as  seen  from  the  eastward;  L,  the  dome,  Mount  Loa;  K,  Mount  Kea. 

As  shown  on  the  map,  Fig.  227,  three  great  cones  make  up  nearly  the 
whole  of  Hawaii,  although  the  island  is  93  miles  from  north  to  south  and  80 
miles  broad.  These  three  cones  are  Mount  Kea,  now  extinct,  13,805  feet  high ; 
Mount  Hualalai,  in  eruption  in  1801,  8275  feet ;  and  Mount  Loa,  now  in  fre- 
quent eruption,  13,675  feet.  Kilauea,  to  the  east  of  Mount  Loa,  is  another 


230. 


Length  3:69  miles 
Width1.:75     a 


Fig.  229,  crater  of  Mount  Loa  (J.  M.  Alexander) ;  Fig.  230,  crater  of  Kilauea  (Hawaiian  Government 
Survey)  in  1886;  V,  Volcano  House;  H,  the  great  lake-basin  Halemaumau,  emptied  after  an  eruption  in  1886. 
Fig.  231,  same  basin  containing  a  debris-cone  6  months  after  the  eruption.  Levels  of  the  floor  of  Kilauea,  in 
Fig.  230,  are  measured  from  the  level  of  the  Volcano  House,  at  V. 

active  volcano,  but  it  makes  the  eastern  flank  of  Mount  Loa,  and  projects 
where  highest  hardly  300  feet  above  the  plain  between  it  and  the  Mount  Loa 
slopes.  The  Kohala  Range,  on  the  north  point,  is  the  half-buried  remains  of 
a  volcano  of  unknown  extent,  which,  as  its  valleys  indicate,  long  since  became 


270 


DYNAMICAL   GEOLOGY. 


extinct.  Fig.  228  represents  a  nearly  north-and-south  section  of  the  island 
through  Mount  Loa  and  Mount  Kea.  The  slopes  of  Mount  Loa  are  5°  to  8°, 
except  over  its  broad  nearly  flat  summit ;  of  Mount  Kea,  5°  to  10° ;  and  the 
eastern  slopes  of  Kilauea,  only  3°.  The  map  of  Hawaii  shows  also,  by  the 
dark-dotted  areas,  the  courses  of  its  great  lava-streams  since  1840. 

Figs.  229  and  230  are  maps,  on  a  scale  of  9000  feet  to  the  inch,  of  the 
crater  at  the  summit  of  Mount  Loa  (Fig.  229)  and  that  of  Kilauea  (Fig.  230), 
after  an  eruption  in  1886. 

Fig.  232  is  an  excellent  view  of  the  crater  of  Kilauea  as  it  appeared  in 
1864,  taken  from  the  north  side.  It  differs  little  from  that  of  recent  years, 
except  in  the  low  ridge  over  the  bottom  toward  its  left  side. 

232. 


Kilauea,  from  the  north,  just  west  of  the  Volcano  House.    Perry. 

Maui  (Fig.  160),  the  island  just  northeast  of  Hawaii,  affords,  in  its  east- 
ern half,  another  good  example  of  a  lava-cone ;  its  height  is  10,032  feet,  and 
the  crater,  called  Haleakala,  is  2500  feet  deep. 

Cinders,  or  the  material  of  high  projectile  discharges,  form  cinder-cones 
(Fig.  233),  having  slopes  commonly  of  35°  to  40°,  but  made  somewhat  lower 

after  their  formation,  through  the  winds, 
rains,  and  surface  earth-slipping.  They 
have  narrow  summits  and  craters. 

If  the  cinders  are  wet  by  heavy  rains,  or 
otherwise,  so  as  to  flow  like  mud,  the  cone 
formed  has  a  broad  top,  a  saucer-like  crater, 
and  slopes  generally  of  15°  to  25°,  and  is  a 
tufa-cone.  The  sides  may  spread  out  below 
Figs.  234  and  235  are  tufa-cones.  They  show  the 


233. 


Assumption  Island,  Northern  Ladrones. 
D.  '41. 


at  a  very  small  angle. 


HEAT. 


271 


great  breadth  of  the  crater ;  but  the  exterior  has  lost  its  natural  slopes  by 
denudation.  In  Fig.  235  the  cone  to  the  left  shows  the  dip  of  the  layers 
of  tufa  inward  toward  the  center  of  the  crater  and  outward,  down  the  outer 
slopes.  Driblets  pile  up  the  fantastic  driblet-cone,  which  has  no  crater  but 
simply  a  hole  for  the  projection  of  lava  in  small  liquid  masses,  drops,  drib- 
lets, or  worm-like  streamlets. 

234. 


235. 


Tufa-cones,  Oahu.  Fig.  234,  a,  the  tufa-cone,  Diamond  Head,  east  of  Honolulu,  the  exterior  eroded; 
6,  c,  other  smaller  cones;  Fig.  235,  Koko  Head  tufa-cones,  east  cape  of  Oahu,  the  one  to  the  left  cut  through 
by  the  sea,  that  to  the  right  eroded  inside  as  well  as  outside.  D. 

Still  another  kind  of  cone,  occasionally  observed  in  Kilauea,  is  the  debris- 
cone,  made  at  times  in  Halemaumau  after  a  discharge  out  of  the  masses  or 
fragments  that  fall  into  the  basin  from  its  steep  sides.  (See  Fig.  231.) 


236. 


237. 


Driblet-cone  of  Kilauea.    D.  '40. 


Driblet-cone.    Brigham,  '64. 


At  an  eruption,  the  discharged  lava :  (1)  may  flow  down  the  mountain 
in  great  streams  from  the  crater  at  the  summit ;  or  (2)  may  escape  to  the 
surface  through  breaks  or  fissures  made  by  the  eruptive  forces  in  the  moun- 
tain's sides,  and  thence  spread  away  in  streams ;  or  (3)  it  may  flow  off 
through  fissures  into  underground  cavities  between  the  old  lava  streams  of 
the  mountain,  or  it  may  only  fill  the  opened  fissures.  Discharges  from  the 
crater  are  probably  the  prevailing  kind  at  the  commencement  of  a  volcano, 
the  lavas  then  pouring  out  copiously.  But  at  the  present  time  the  outflows 
are  mostly  or  wholly  from  fissures,  though  often  subterranean. 


272  DYNAMICAL   GEOLOGY. 

The  outflow  from  fissures  may  take  place  at  any  height  on  the  mountain, 
and  also  beneath  the  sea  level.  If  at  the  latter,  the  eruptions  are  submarine; 
if  at  the  former,  surficial,  that  is,  subaerial.  The  map  of  Hawaii  shows  the 
courses  of  seven  of  the  great  lava  streams  of  the  summit  eruptions,  with 
their  dates.  They  all  commenced  some  distance  from  the  crater;  and  the  two 
to  the  south,  those  of  1868  and  1887,  at  points  17  and  12  miles  from  it,  and 
12  and  17  from  the  coast.  Only  one  lava  stream  from  Kilauea  is  shown, 
that  of  1840,  on  the  eastern  point  of  the  island ;  all  its  later  discharges  have 
been  subterranean. 

The  fissures  for  the  discharge  of  lavas  are  often  so  wide  in  some  places 
that  they  pour  out  the  lavas  there  for  weeks,  and  make  cones  of  lava  over 
each  wide  place ;  or  if  the  lava  ceases  to  flow  out,  there  may  be  projectile 
discharges  for  a  time  and  cinder-cones  may  be  made.  In  either  case  a  line 
of  cones  (Fig.  234)  may  be  formed  over  the  fissure.  Such  cones  while  in 
action  are  true  volcanoes  in  all  their  characters.  They  are  distinguished  as 
the  lateral  cones  of  a  volcano  or  volcanic  mountain.  The  lateral  cones  of  a 
submarine  eruption  often  stand  as  islands,  or  make  shoals,  off  a  coast. 

Lavas  and  other  igneous  rocks.  —  The  kinds  of  igneous  rocks  have  been 
described  on  pages  84  to  89.  There  are  many  of  them,  but  petrology  makes 
distinctions,  based  on  texture  and  accessory  minerals,  which  have  importance, 
but  are  not  always  of  fundamental  value.  These  rocks  consist  ordinarily 
of  a  kind  of  feldspar,  or  occasionally  of  some  other  related  alkali-bearing 
mineral,  usually  with  some  additional  mineral,  as  pyroxene,  hornblende, 
chrysolite  (olivine),  quartz,  mica,  and  a  few  other  species.  But  hornblende 
when  fused  turns  to  pyroxene ;  chrysolite  may  form  from  fused  pyroxene ; 
and  mica  may  be  derived  at  a  high  temperature  from  feldspar.  Further,  all 
textures  from  that  of  glass  to  granite-like  may  exist  in  the  igneous  sheet 
or  mass  of  a  single  ejection  —  the  differences  depending  on  rate  of  cooling. 

The  distinctions  between  granite,  granulyte,  rhyolyte,  and  quartz-felsyte,  between 
trachyte  and  felsyte,  between  gabbro  and  doleryte,  between  chrysolitic  gabbro  and 
basalt,  between  andesyte  and  dioryte,  between  dacyte  and  quartz-dioryte,  are  differences 
chiefly  in  texture  —  a  character  of  inferior  value  geologically,  although  a  sufficient  reason 
for  their  having  names  in  petrology.  The  minerals  pyroxene  and  hornblende  are  essen- 
tially the  same  in  composition,  and  they  are  also  mutually  convertible  under  certain  heat- 
conditions,  as  explained  beyond,  and  hence  pyroxenic  and  hornblendic  rocks  are  very 
closely  related ;  but  the  distinction,  notwithstanding  the  degree  of  resemblance,  is  often 
of  great  geological  interest. 

Igneous  rocks  are  fusible  kinds.  No  lava  streams  or  dikes  have  been 
found  about  volcanoes  consisting  of  the  "  infusible  "  minerals  quartz,  hema- 
tite, magnetite.  But  grains  of  these  minerals  are  common  in  the  rocks. 

Besides,  there  are  often  minute  grains  of  native  iron  in  some  igneous  rocks,  especially 
in  the  basaltic ;  and  large  masses  of  iron  have  been  found  in  the  basalt  of  Disco  Island, 
Greenland,  and  of  copper  in  the  related  igneous  rock  of  the  Lake  Superior  copper  region 
in  Michigan.  The  copper  probably  resulted  from  the  reduction,  by  the  heat,  of  copper  ore 


HEAT.  273 

encountered  on  the  way  up  ;  and  the  same  may  be  true  of  the  iron,  the  reduction  in  this 
case  having  been  effected,  as  J.  L.  Smith  suggested,  by  the  aid  of  some  carbon  compound 
in  the  ascending  liquid  basalt.  But  it  may  be  that  the  iron  was  carried  up  by  the  liquid 
rock  from  the  earth's  interior. 

Some  igneous  rocks  consist  chiefly  of  the  "infusible  "  minerals  chrysolite  and  leucite  ; 
but  the  complete  fusion  which  the  capability  of  flowing  indicates  is  evidence  that  some 
part  of  the  constituents  of  these  rocks  before  ejection  were  in  fusible  combinations.  By 
infusible  is  here  meant  infusible  before  the  common  blowpipe. 

The  more  important  volcanic  phenomena  connected  with  these  rocks 
depend  on  the  temperature  of  fusion,  those  requiring  the  least  heat  being 
the  earliest  to  fuse  as  the  temperature  rose,  and  the  longest  to  continue 
liquid  as  it  declined,  and,  therefore,  those  that  have  commonly  had,  when 
ejected,  the  temperature  of  the  freest  liquidity. 

There  are  three  prominent  classes  of  igneous  rocks,  differing  in  fusibility. 
In  each  class  the  kinds  are  nearly  alike  in  chemical  constitution,  but  differ 
somewhat  mineralogically  and  in  state  of  crystallization.  There  are  inter- 
mediate kinds ;  but  still  the  classes  stand  out  prominently.  These  three 
groups  are  as  follows  :  — 

1.  Easy  fusibility.  —  The  BASALTIC  CLASS  :    These  fuse  at  about  2250°  F. 
(C.  Barus);  consist  chiefly  of  pyroxene  (or  a  related  species),  and  of  the 
feldspar,  labradorite,  whose  alkalies  are  lime  and  soda;  they  often  carry 
grains  of  chrysolite,  but  very  rarely  of  quartz :  as  basalt,  doleryte,  diabase, 
gabbro,  etc.     These  rocks  are  basic  (pages  65,  86);  but  fusibility,  not  basicity, 
is  the  important  characteristic  as  regards  volcanic  phenomena ;  for  anorthite, 
the  most  basic  of  the  feldspars,  is  one  of  the  most  infusible. 

2.  Medium  fusibility  (about  2520°  F.,  Barus). — The   AXDESYTE   CLASS: 
These  consist  of  a  mineral  of  the  pyroxene-hornblende  group,  and,  as  the 
feldspar  portion,  of  oligoclase  or  andesite,  whose  alkalies  are  soda  and  lime ; 
they  often  carry  quartz  grains  :  as  andesyte,  dacyte,  quartz-andesyte,  dioryte, 
and  related  kinds. 

3.  Difficult  fusibility  (about  2700°  F.,  Barus,  for  quartz-trachyte  or  rhyo- 
lyte).—  The  TRACHYTE  CLASS:  These  consist  of  potash-feldspar,  orthoclase, 
or  of  orthoclase  with  a  little  oligoclase,  or  albite ;  sometimes  containing  mica, 
pyroxene,  hornblende,  quartz :  as  trachyte,  rhyolyte,  felsyte,  granite,  etc. 
Rhyolyte  is  quite  viscid  even  at  3100°  F.  (Barus). 

Lavas,  especially  the  trachytic  and  andesytic  kinds,  and  including  lithoid  obsidian, 
have  frequently  a  thin  laminated  structure,  which  is  produced,  not  by  a  succession  in 
streams,  the  laminae  being  too  thin  for  streams,  but  by  successive  action  in  the  supply  of 
lava  at  the  point  of  outflow ;  the  incipient  subdivisions  are  drawn  out  as  the  stream 
flows  into  thin  sheets  or  layers  (Iddings). 

Fouque  and  L6vy  obtained  from  fused  basalt  on  cooling  after  being  for  48  hours  at 
white-red  fusion,  "  a  temperature  above  the  melting-point  of  pyroxene  and  labradorite," 
"crystals  of  olivine  in  a  brownish  vitreous  magma";  but  on  cooling  from  cherry-red  fusion 
sustained  for  48  hours,  numerous  microlites  of  labradorite  and  pyroxene  with  magnetite. 

Messrs.  Ch.  and  G.  Friedel  (1890),  on  heating  mica  to  500°  C.  (900°  F.)  with  alkaline 
DANA'S  MANUAL  — 18 


274  DYNAMICAL   GEOLOGY. 

solutions,  obtained  crystals  of  nephelite  and  orthoclase ;  and  with  the  addition  of  silica, 
obtained  leucite. 

As  early  as  1804,  Gregory  Watt  published  in  the  Philosophical  Transactions  "Obser- 
vations on  Basalt,"  in  which  he  gave  a  detailed  account  of  the  melting  of  700  pounds  of 
basalt  from  Rowley-Rag  (G  =  2-743)  to  glass,  and  of  its  becoming,  on  slow  cooling,  a 
gray,  crystalline-granular  mass  (with  G  =  2-934-2-949)  consisting  of  spherical  concretions, 
many  2  inches  in  diameter  and  having  a  somewhat  radiated  structure  (which  was  mostly 
lost  with  the  slowest  cooling) ;  and  of  the  adjoining  concretions  being  often  rendered 
hexagonally  prismatic  from  contact,  whence  he  inferred  the  concretionary  origin  of 
basaltic  columns. 

2.   Conditions  Determining  the  Forms  of  Cones. 

1.  Dependence  on  fusibility  of  the  lavas.  —  Cones  of  lavas  of  the  basalt 
class  are  of  gentle  slope,  and  great  breadth,  owing  to  the  easy  flow  of  the 
rock.  The  lavas  are  glassy  only  at  surface,  or  when  in  scoriaceous  forms. 

The  craters  also  derive  their  characters  from  the  liquidity.  They  are 
broad,  with  the  walls  often  vertical,  meriting  the  name  they  have  of  pit- 
craters,  as  is  well  seen  in  figures  229-231,  on  page  269. 

But  the  great  cones  of  western  North  and  South  America  are  mostly 
examples  of  the  andesyte  or  trachyte  class.  The  slope  seldom  exceeds  35°, 
except  where  caused  by  breaks.  The  steepness,  however,  may  be  in  part 
owing  to  intercalated  beds  of  cinders  or  tufa.  Mount  Shasta,  represented 
in  Fig.  226,  is  one  of  them,  — its  slopes  28°-32°  (Whitney).  Chimborazo, 
20,498  feet  high,  has  angles  of  about  25°  in  a  view  looking  northeast ;  Coto- 
paxi,  19,613  feet  high,  in  a  westward  view,  angles  of  27-J-0  to  30|-0,  rising  near 
the  summit  to  37°  (Whymper);  and  Arequipa,  angles  of  27|°  to  32°  50'. 

Trachytes,  and  other  lavas  of  the  third  class,  take  part  in  cones  of  the 
second  kind.  But  as  the  temperature  of  free  fusion  is  above  3100°  F.,  the 
heat  required  for  complete  liquidity  is  generally  wanting,  so  that  at  the 
time  of  ejection  they  commonly  are  already  in  a  pasty  state,  or  that  of 
incipient  solidification.  The  streams  are  thick,  compared  with  the  basaltic. 
Sometimes  the  lava  swells  up  into  steep  and  lofty  crate rless  domes,  instead 
of  flowing  away  in  streams.  The  high  domes  of  Auvergne,  France,  are 
examples.  But  when  a  trachytic  lava  has  the  heat  of  complete  fusion,  it 
may  flow  and  make  great  streams. 

The  following  sketch  represents  "Gothic  Mountain,"  in  Colorado,  in 
which  a  mountain  mass  of  trachyte  rests  on  a  base  of  Cretaceous  rocks, 
much  eroded  over  its  surface.  (Hayden  Rep.,  1873.)  In  the  nearly  hori- 
zontally stratified  base  there  is  an  independent  .dike  of  the  trachyte,  which 
was  probably  produced  contemporaneously  with  the  outflow  that  made  the 
mountain.  The  mountain  is  nearly  2000  feet  in  height  above  the  Cretaceous 
base,  and  12,465  feet  high  above  the  sea  level.  The  rock  is  without  bedding 
or  any  evidence  of  separate  lava  flows. 

Melted  beeswax  poured  out  on  a  flat  surface,  while  heated  above  the 
fusing  point,  would  flow  off  at  a  very  small  angle ;  but  if  its  temperature 
were  below  that  of  fusion,  it  would  be  pasty,  and  the  angle  of  flow  would 


HEAT.  275 

increase  as  the  temperature  decreased.  Copious  streams  would  have  the 
smaller  angle,  while  small  streams  would  give  increased  pitch,  and  drops 
might  make  a  vertical  column.  The  facts  with  regard  to  lavas  are  the  same 
in  principle ;  for  basaltic  cones,  as  in  those  of  driblet  origin,  may  have  high 
angles,  even  90°. 

238. 


Gothic  Mountain,  Colorado.    A  trachytic  masB  overlying  Cretaceous  rocks. 

If  lavas  were  as  liquid  as  water,  cones  of  sensible  slope  would  be 
impossible ;  the  most  liquid  have  sufficient  viscidity  or  cohesion  to  cause 
some  resistance  to  free  movement,  and  the  slope  is,  in  a  sense,  a  measure  of 
this  resistance. 

2.  Dependence  of  the  forms  of  lava-cones  on  place  and  amount  of  discharge. 
—  Since  a  cone  diminishes  in  diameter  upward,  a  flow  of  lava  from  the  summit 
region,  having  like  width  throughout,  would  cover  a  much  larger  part  of  the 
circumference  in  the  upper  part  than  in  the  lower.  The  part  of  the  cone 
below  would  require  in  fact  a  great  number  of  ordinary  lava  streams  to  make 
one  coat  over  the  surface.  The  consequence  of  this  condition  is  that  such 
discharges  add  to  the  height  and  make  the  cone  steeper  above,  and  give  it 
also  a  concave  outline.  But  if  the  flows  commence  for  the  most  part  a  little 
below  the  summit,  from  an  eighth  to  a  sixth  of  the  height,  the  upper  part 
will  be  widened  and  the  cone  take  the  form  of  a  low  dome,  like  Mount  Loa; 
or  if  the  streams  come  from  fissures  in  the  lower  part  of  the  cone  and  spread 
beyond  the  base,  the  cone  will  be  flattened  below,  and  the  lower  part  of  the 
profile  will  be  made  concave. 

Lava-cones  often,  perhaps  generally,  derive  an  oblong  or  parabolic  form  of  area  from 
their  origin  over  a  fissure.  The  fissure  was  made  by  a  profound  rupture  of  the  earth's 
crust,  and  probably  the  location  of  the  crater  was  fixed  by  its  intersection  with  a  trans- 
verse fissure  ;  but  along  the  larger  of  the  fissures  an  elongate  form  is  given  to  the  crater. 
The  chief  focus  of  action  is  usually  toward  one  extremity.  Over  the  slopes  of  the  moun- 
tain, the  belt  in  the  direction  of  the  longer  axis  is  likely  to  be  the  region  of  most  frequent 
eruptions  and  of  long  lines  of  steaming  fissures.  The  craters  of  both  Mount  Loa  and 


276  DYNAMICAL   GEOLOGY. 

Kilauea  are  thus  elongated  and  eccentric,  and  have  lines  of  fissures  extending  far  to  the 
southwest  in  the  direction  of  the  longer  axis ;  moreover,  the  former  has  the  larger  part 
of  its  more  recent  eruptions  either  to  the  north-northeast  or  south-southwest  of  the  crater. 
The  two  craters  of  Maui  are  also  elongated  and  eccentric.  The  position  of  the  present 
vent  of  Vesuvius  with  reference  to  the  original  Mount  Somma  is  eccentric,  according  to 
Johnston-Lavis,  and  perhaps  for  a  like  reason. 

3.  Causes  influencing  the  forms  of  cinder-  and  tufa-cones.  —  Cinder-cones 
have  their  forms  varied  in  height,  breadth,  and  slope,  on  the  different  sides, 
by  the  winds.  Moreover,  alternations  of  cinder  and  lava  ejections  make 
a  cone  of  steeper  slope  than  lava  alone.  Summit  ejections  of  cinders  may 
increase  the  height  without  adding  much  to  the  mass  of  a  mountain.  Mount 
Kea  owes  its  superior  height  over  Mount  Loa  to  a  final  spurt,  when  it  was 
becoming  extinct,  cinder-cones  at  the  top  having  been  then  thrown  up. 

Flowing  volcanic  mud,  from  which  tufa  and  tufa-cones  are  made,  neces- 
sarily produces  broad-topped  cones  with  a  saucer-like  crater,  as  explained  on 
page  270 ;  but  the  winds  often  carry  cinders  far  away  to  make  horizontal 
deposits,  which  sometimes  attain  great  thickness.  By  making  an  outline  of 
a  section  of  a  cone  and  drawing  lines  parallel  to  the  sides,  as  below,  sec- 
tions representing  in  a  general  way  the  structure  of  a  lava-cone,  cinder-cone, 

240. 


Cinder-cone.  Tufa-cone. 

and  tufa-cone  are  easily  made.  But  it  is  to  be  noted  that  such  sections  are 
incorrect,  since  lava  streams  and  cinder  deposits  are,  to  a  large  extent,  strips 
or  patches  over  the  surface  of  the  cone  and  not  a  series  of  seamless  coats. 

4.  Relations  of  glassy  lavas  to  the  stony.  —  Glassy  forms  of  lava  (see  page 
77)  occur  with  each  of  the  three  kinds,  but  make  no  cones.  With  basaltic 
lavas  they  constitute  merely  a  crust  on  a  lava  stream,  or  the  scum  of  a  lava 
lake ;  but  in  a  trachytic  volcano,  the  glass,  called  obsidian,  sometimes  flows 
in  streams. 

"Obsidian  Cliff"  in  the  Yellowstone  Park  is  a  remarkable  example  of  an  obsidian 
outflow.  It  has  the  columnar  forms  of  Fig.  224.  The  glass  is  connected  with  vast  erup- 
tions of  rhyolyte  (quartz-trachyte)  at  and  about  Mount  Washburn,  which  have  a  thickness 
of  thousands  of  feet,  and  succeeded  to  andesyte  eruptions  (Iddings,  Hague).  Another 
locality  has  been  reported  by  Russell  near  Mono  Lake,  in  western  Nevada.  On  the  trachyte 
islands,  north  of  Sicily,  Lipari  (1601  feet  high)  and  Vulcano  (1978  feet),  the  obsidian 
streams  bear  evidence  of  sluggish  twisting  flow  (Judd,  1875).  With  the  glass  occurs 
pumice,  and  that  of  Lipari  is  the  pumice  of  the  arts.  The  northern  island  of  the  group, 
Stromboli  (3090  feet  high),  is  basaltic  in  its  lavas  ;  the  islands  intermediate  between 
Stromboli  and  Lipari  have  lavas  of  intermediate  kinds. 


HEAT.  277 

5.  Sizes  of  some  of  the  larger  craters.  —  Kilauea  has  diameters  of  14,000 
and  9800  feet ;  the  depth  in  1840  was  about  1000  feet,  but  now  it  is  less 
than  450  feet.  The  crater  of  Haleakala,  east  Maui,  is  23  miles  in  circuit 
and  2500  feet  in  greatest  depth.  The  crater  of  the  peak  of  Teneriffe  is  8 
miles  by  6  in  area,  and  has  a  depth  in  some  parts  of  2000  feet.  Mauritius 
has  a  crater  which  measures  at  least  13  miles  in  its  longest  diameter.  On 
Java,  Papandayang,  7084  feet  high,  has  a  crater  whose  diameters  are  15  and 
6  miles.  The  crater  of  Aso-san,  of  the  island  of  Kiusiu,  Japan,  has  diame- 
ters, according  to  Milne,  of  about  10  and  14  miles. 

3.   Volcanic  Action  and  its  Causes. 

Volcanic  action  involves  the  continued  supply  of  liquid  lava  from  depths 
below  the  earth's  surface  to  the  crater,  to  keep  up  heat  and  action.  It 
comprises  (1)  work  within  the  crater  by  means  of  escaping  vapors,  by  the 
fusing  and  contractional  effects  of  heat,  and  by  gravitational  pressure ;  and 
(2)  discharges  of  lava,  either  in  streams  or  as  cinders. 

1.  The  supplying  of  lava.  —  The  supply-channel,  or  conduit,  of  a  volcano 
must  reach  down  to  a  region  of  great  heat  and  fusion.      For  the  liquid 
column  loses  heat  from  contact  with  the  air  and  cool  rocks,  and  from  the 
expansion  of  vapors  or  vaporizable  material  within  the  lava.     This  supply 
of  liquid  rock  presupposes  some  upthrusting  force.     If  the  level  reached  by 
the  upthrust  lavas  is  much  below  the  earth's  surface,  the  heat  of  the  melted 
rock  might  make  hot  springs  or  geysers,  or,  at  a  higher  level,  produce  a 
region  of  escaping  vapors.     But,  for  volcanic  action,  the  ascensive  force  must 
be  sufficient  to  restore  the  lava-column  to  its  mean  height  in  the  crater, 
sooner  or  later  after  every  eruption ;  for  failure  here  is  the  beginning  of 
decline  in  volcanic  activity.     When  a  volcano  ceases  action  entirely,  not 
even  vapors  escaping,  it  is  said  to  be  extinct;  but  it  may  not  be  so  dead 
that  a  century  later  it  will  not  break  out  anew. 

The  conduit  of  lava  beneath  an  active  crater  probably  has  nearly  the 
diameter  of  the  crater,  judging  from  facts  observed  at  Kilauea.  This  would 
give  for  the  Kilauea  conduit  a  breadth  of  two  to  three  miles. 

2.  The  escaping  vapors.  —  The  work  done  in  a  crater  is  largely  owing  to 
the  making  and  escaping  of  vapors.     For  if  all  vaporizable  material  were 
absent,  the  lavas  would  lie  quiet.     The  liquid  lavas  in  sight  in  a  crater  are 
always  in  constant  activity ;  and  if  below  but  out  of  sight,  there  is  usually 
considerable  noisy  action  from  escaping  steam,  and  from  the  movements 
which  the  steam  occasions. 

The  vapors  of  a  volcano  are  99  per  cent  vapor  of  water,  as  has  been 
ascertained  by  investigation.  For  the  supply  of  water  the  sea  is  one  prob- 
able source ;  the  rains,  another ;  and  vapors  coming  up  from  depths  below, 
with  the  lavas,  a  third  source.  Vapors  from  the  "  depths  below  "  are  from 
the  subterranean  source  of  the  lavas,  and  this  source  may  be  either  a  per- 
petual lava-sea  of  large  extent,  if  such  exists,  or  the  rocks  of  the  crust  that 


278  DYNAMICAL   GEOLOGY. 

have  been  melted  to  produce  the  supply,  since  all  rocks  of  the  supercrust 
contain  traces  of  moisture  (page  205).  But  this  is  not  the  chief  source  of 
the  vapor  of  water. 

Among  the  other  materials  of  the  vapors,  sulphurous  acid  (S02)  is  probably  the  most 
abundant.  It  has  the  smell  of  burning  sulphur.  It  is  always  present,  and  probably  comes 
from  iron  sulphides  in  the  melted  rocks,  since  they  are  often  sparingly  present  in  the  solid 
lavas.  Hydrogen  is  sometimes  present ;  it  may  come  from  the  dissociation  of  the  elements 
of  water  (H20),  or  from  any  oxidation  in  the  lava  in  which  the  oxygen  used  is  derived 
from  water.  Hydrochloric  acid  (HC1)  is  one  of  the  gases  when  sea  water  gains  admission 
to  the  hot  lavas.  Carbonic  acid  (C02)  may  be  emitted  if  any  limestone  (CaO.CO2)  exists 
below  in  proximity  to  the  melted  lavas.  Carbonic  oxide  (CO)  has  been  detected  by  W. 
Libbey  in  spectroscopic  observations  of  the  flames,  1,  2,  or  3  feet  high,  that  appear  about 
the  lava  vents  of  Kilauea.  The  above,  with  more  or  less  of  atmospheric  air,  are  the 
chief  gases  of  the  melted  lavas.  There  are  other  vapors  given  out  by  solfataras,  but  these 
take  no  part  in  the  eruptive  work  of  the  volcano. 

The  mechanical  work  of  the  vapors  is  due  almost  wholly  to  the  vapor 
of  water.  In  view  of  the  relation  on  Hawaii  between  times  of  eruptions 
and  the  rainy  season,  and  between  length  of  lava-column  above  the  sea  and 
projectile  force,  there  is  strong  probability  that  fresh  waters  are  in  many 
volcanoes  the  chief  agent.  Whenever  subterranean  waters  in  their  descent 
below  the  surface  approach  the  hot  rocks  about  the  lava-column,  they  are  con- 
verted into  steam  ;  and  the  amount  of  steam  generated  from  even  a  small  con- 
tinued supply  of  water  would  be  so  large  (in  view  of  the  fact  that  at  the 
ordinary  pressure  one  cubic  foot  of  water  will  yield  1700  cubic  feet  of  steam) 
that  it  could  not  all  escape  outward  through  the  rocks,  but  in  part  would  be 
forced  into  the  rising  lavas  of  the  conduit.  Moreover,  it  has  been  experi- 
mentally demonstrated  by  Daubre"e  (1879)  that,  under  such  circumstances,  a 
molecular  absorption  of  the  steam  would  take  place  against  any  pressure 
outward  that  might  exist  within  the  heated  column. 

3.  Effects  of  vapors.  —  (a)  Projectile  effects.  —  The  escape  of  vapor  and  its 
expansion  encounter  resistance  in  consequence  of  the  cohesion  of  the  liquid 
material,  which  resistance  is  proportional  to  the  strength  of  this  cohesion, 
or  is  conversely  as  the  degree  of  liquidity.  Water,  in  boiling,  lets  very 
small  bubbles  of  steam  through  easily ;  and  the  elastic  force  of  the  steam 
of.  the  bubble  makes  low  jets,  one  or  two  inches  in  height.  But  the  elastic 
force  of  a  small  bubble  of  vapor  is  too  feeble  to  break  its  way  through  lava ; 
enlargement,  therefore,  goes  on  until  the  force  is  sufficient  to  overbalance 
the  resistance ;  then  comes  the  break  of  the  liquid  lava-shell  of  the  bubble, 
and  the  projection  of  its  fragments  vertically  or  nearly  so  into  the  air,  — 
vertically,  because  the  shell  is  thinnest  at  top.  The  projectile  force  thus 
depends  largely  on  the  size  of  the  bubble,  or,  what  is  equivalent,  on  the 
viscidity  of  the  liquid  lava,  and  on  the  rate  of  supply  of  vapors  seeking  to 
escape. 

On  account  of  the  remarkable  liquidity  of  basaltic  lavas,  the  projectile 
force  required  to  break  a  way  through  may  be  so  small  as  to  throw  the  lava 


HEAT.  279 

to  a  height  of  only  8  or  10  yards,  as  in  Kilauea,  —  a  height  so  small  that 
the  projected  drops  or  masses  of  lava  fall  back  unsolidified,  and  the  jets 
dance  in  a  lively  and  brilliant  way  over  the  surface  of  the  lava-basin.  The 
scene  is  a  brilliant  one,  when  a  lake  of  lava  500,000  square  feet  in  area  is 
covered  throughout  with  the  playing  jets,  as  at  Kilauea  in  1840. 

It  is  a  mark  also  of  such  extreme  liquidity,  that  where  the  escaping  vapors  throw  up 
the  lavas  in  half -covered  places  under  the  rocky  sides  of  a  lake,  the  lavas  in  the  recoil  dash 
out  in  fiery  spray  much  like  the  spattering  of  breaking  waves.  In  the  pulling  apart  of  the 
rising  lava-jet  dividing  it  into  drops,  the  glassy  material  in  fusion  is  drawn  out  into  hairs, 
and  forms  the  "  Pele's  hair  "  of  Kilauea. 

In  cases,  outside  of  the  lava-lakes,  where  the  bubbles  are  bursting  beneath  an  open- 
ing in  the  bottom  of  the  crater,  the  vapors  and  lava  driblets  escape  from  the  aperture  with 
a  rush  and  a  roar,  "  as  if  all  the  steam  engines  of  the  world  were  concentrated  in  it." 
(Douglas.)  The  driblet-cone,  thus  made,  is  sometimes  called  a  blowing-cone. 

Now  and  then  the  regular  ebullition  is  interrupted  by  larger  throws,  even  to  200  feet. 
At  other  times  the  lake  becomes  crusted  over  with  a  glassy  scum,  or  with  a  crust  of  more 
solid  lava,  and  so  remains  for  a  while  ;  and  then  —  at  intervals  of  minutes,  or  hours,  o~ 
longer  —  it  breaks  anew  into  activity,  attended  with  a  remelting  of  what  had  solidifiea^ 
and  the  throwing  up  of  jets  as  before. 

In  the  Mount  Loa  crater,  situated  13,675  feet  above  the  sea  (10,000  feet 
above  Kilauea),  the  jets  generally  rise  200  feet  or  more,  and  instead  of  the 
quiet  ebullition  of  Kilauea  there  is  the  play  of  a  great  fiery  fountain.  One 
of  the  describers  states  that  in  1873  the  "  fountain  of  fire,"  150  feet  broad, 
played  in  several  united  but  independent  jets  to  a  height  of  150  to  300  feet. 
At  one  time  the  jets  suddenly  became  low,  and  continued  thus  for  a  few 
seconds,  then  "  with  a  roar  like  the  sound  of  gathering  waters,  nearly  the 
whole  surface  of  the  lake  was  lifted  up,  and  its  whole  radiant  mass  rose 
three  times  in  one  outburst  to  a  height,  as  estimated  by  the  surrounding 
cliffs,  of  600  feet.  After  this  the  fountain  played  as  before  with  jets  of  300 
feet."  (I.  L.  Bird,  1876.)  Others  report  heights  of  600  to  800  feet  in  the 
playing  fountains.  These  are  the  conditions  in  the  Mount  Loa  crater  only 
when  eruptions  are  imminent. 

The  cause  of  this  high  projection  of  the  lavas  in  fountain-like  form  in  a  summit  crater 
can  be  no  other  than  the  escaping  vapors ;  and  the  difference  between  such  fountains 
and  the  gentler  ebullition  of  Kilauea  must  depend  on  their  amount  and  rate  of  supply. 
Such  moisture,  if  the  deep  subterranean  region  of  lavas  were  its  source,  would  be  most 
abundant  in  the  equally  large  but  10,000  feet  lower  crater,  Kilauea.  But  if  supplied  by 
the  fresh  waters  from  the  rains  over  the  region,  the  10,000  feet  of  greater  altitude  are  a 
sufficient  reason  for  the  difference. 

The  idea  was  put  forth  by  Scrope  that  the  fusion  in  the  lavas  of  a  volcano  was  aqueo- 
igneous  fusion,  or  a  mobility  due  in  part  to  the  water-vapor  present.  Such  vapor  must 
increase  the  liquidity,  but  facts  show  that  it  is  not  dependent  on  it.  The  white  light 
which  the  lavas  of  Kilauea  often  display  in  their  "ebullition"  is  evidence  of  heat  suf- 
ficient for  fusion.  Bartoli,  on  Etna  in  1893,  found  the  temperature  of  a  lava  stream,  at 
its  exit,  1910°  F. 


280  DYNAMICAL   GEOLOGY. 

Vesuvius,  with  its  less  liquid  lavas,  contrasts  wonderfully  in  its  way  of 
working  with  the  volcanoes  of  Hawaii.  In  the  case  of  such  lavas,  the 
bubbles  have  to  become  large  before  the  vapor  can  break  through.  Conse- 
quently, whenever  the  break  occurs,  the  accumulated  explosive  force  projects 
the  fragments  of  the  lava-shell,  that  is,  the  so-called  volcanic  ashes,  or  lapilli, 
to  a  height  of  hundreds  or  thousands  of  feet  —  even  10,000  in  some  Vesuvian 
eruptions. 

Such  high  projections  are  the  common  fact  at  most  volcanoes.  Great  viscidity,  while 
leading  to  the  production  of  large  size  in  the  vapor-made  bubbles  before  they  are  ready 
for  explosion,  makes  fewer  of  them  form  over  a  given  surface  of  liquid  lava  ;  and  in 
times  of  moderate  activity  the  number  may  be  but  half  a  dozen,  or  only  a  single  one,  at  a 
time,  while  on  a  like  area,  lavas  with  the  Kilauea  degree  of  viscidity  would  have  scores  or 
hundreds.  When  the  author  was  at  Naples,  in  May,  1834,  there  was  at  night  an  interval 
of  7  to  8  minutes  between  the  explosions,  or  the  throws  (some  hundreds  of  feet  in  height) 
of  fiery  cinders ;  on  the  ascent,  the  following  day,  the  interval  was  4  to  5  minutes ;  and 
on  passing  Stromboli,  a  fortnight  later,  June  16,  it  was  15  to  20  minutes,  — the  activity 
being  less  than  usual,  explosions  every  2  or  3  minutes  being  common.  As  Spallanzani, 
Hofmann,  and  others  have  seen  the  rising  bubble  within  Stromboli,  the  bursting,  and, 
following  this,  the  rush  of  vapor  and  the  cinder  projections,  there  is  no  reason  to  doubt 
that  at  Vesuvius,  also,  each  throw  of  cinders  had  the  same  source.  Mr.  John  Milne 
states  that  on  his  ascent  of  the  Japan  volcano,  Oshima,  in  May,  1877,  on  approaching  the 
top,  successive  explosions  were  heard  every  two  seconds  with  occasional  pauses,  which 
explosions  he  found,  on  reaching  the  top,  to  be  due  to  successive  outbursts  of  steam,  each 
outburst  projecting  to  a  height  of  nearly  6000  feet  ashes  and  lava-fragments  that  descended 
vertically,  unless  wafted  by  the  winds. 

When  the  rains  come  down  in  torrents  during  such  an  eruption,  the  pro- 
jected materials  make  the  flowing  mud  (called  tufa  when  it  is  dried  and 
hardened)  that  buries  fields  and  forests,  and  has  made  fossils  of  cities,  of 
which  Herculaneum  and  Pompeii  are  examples.  Extensive  tufa  deposits 
are  made  by  volcanoes  of  all  kinds,  but  especially  by  those  of  the  second 
and  third  kinds.  Some  accumulations,  apparently  from  a  single  series  of 
discharges,  without  intermediate  streams  of  lava,  have  a  thickness  of  1000 
feet  or  more,  and  cover  thousands  of  square  miles. 

To  the  eastward  of  the  Cascade  summits,  Oregon,  Mr.  Condon  speaks  of  traveling 
over  an  area  of  tufa  for  50  to  60  miles,  and  states  that  the  volcanic  ash  was  evenly  laid 
over  the  whole  surface,  like  a  covering  of  snow  ;  and  where  attaining  its  greatest  thickness, 
the  sharp  features  of  the  older  surface  ceased  to  show  themselves  through  it.  In  many 
parts  of  the  Rocky  Mountain  regions,  the  tufas  contain  silicified  stumps  and  trunks  of 
large  trees  (page  135). 

(b)  Enlarging  and  vesiculating  effects  of  vapors.  —  The  vapors  also  enlarge, 
by  their  expansion,  the  bulk  of  the  liquid  lava,  and  may  thus  increase  the 
height  of  the  lava-column. 

They  also  make  the  vesicles  or  air-cells  of  lavas,  producing  its  vesicular 
and  scoriaceous  varieties.  These  are  their  noiseless  and  unseen  effects, 
while  they  are  still  inside  of  the  lavas.  The  vesicular  lavas  contain  relatively 


HEAT.  281 

few  vesicles  to  the  bulk  of  the  rock,  and  the  scoriaceous  varieties  contain 
many,  so  many  as  to  make  the  rock  light.     Pressure  of  much  overlying  lava 
prevents  vesiculation,  and  this  takes  place,  therefore,  near 
the  surface;  but  it  is  not  ascertained  what  amount  of  pres-  241- 

sure  so  limits  it. 


Ordinary  vesicles  are  usually  oblong,  rather  than  spherical,  unless  [/    f 

the  size  is  quite  small ;  no  distinction  between  those  made  in  volca- 
noes by  different  kinds  of  vapors  has  been  observed.    But  in  some 
streams  of  igneous  origin  (as  in  the  trap  of  the  Connecticut  Valley)        <Q 
they  sometimes  have  the  form  of  slender  cylinders,  2  or  3  inches  long ;    ~          $          ^ 
and  such  elongated  forms  imply  great  expansive  action  at  the  moment    n 

of  vaporization,  and  therefore  point  to  the  vaporization  of  liquid  car-  T 

,       .         . ,          .  Vesicles  in  basalt   at 

bonic  acid  as  the  cause.  Kiama    D  ,49 

Oblong  vesicles  sometimes  are  pointed  at  one  end,  and  thus  show 

the  direction  of  movement  —  that  of  the  blunt  end ;  an  example  from  Kiama,  New  South 
Wales,  is  here  represented. 

The  lightest  of  all  kinds  of  scoria,  called  "thread-lace  scoria,"  has  the 
thin  walls  reduced  to  mere  threads,  as  in  the  annexed  figures  of  a  specimen 
obtained  at  Kilauea.  Fig.  242  represents  a  portion  of  the  scoria,  magnified 
30  times.  Figs.  243  and  244  show  two  forms  presented  by  the  more  regular 
of  the  cells.  The  form  of  Fig.  243,  which  has  12  sides  besides  the  two  bases, 
is  the  most  common.  The  natural  size  of  the  cells  is  -£$  to  ^_.  inch,  though 

242. 

244. 


243. 


Thread-lace  scoria,  from  Kilauea.     x30.    D. 


some  are  much  larger.  This  scoria  contains  only  1-7  per  cent  of  its  bulk 
in  rock-material,  and  hence  a  layer  of  glass  one  inch  thick  would  make  a 
layer  60  inches  thick  of  the  scoria;  and  1-2  per  cent  of  moisture  in  the 
glass  by  weight  would  suffice  to  produce  it. 

The  light  glassy  scum  of  the  lava  of  the  Kilauea  lava-lakes  (like  the  scum  on  ferment- 
ing molasses)  flows  off  as  the  top  of  each  outflowing  stream,  and  cools  as  a  separable 


282  DYNAMICAL   GEOLOGY. 

crust  1  or  2  inches  thick.  Beneath  it,  the  most  recent  lava  is  comparatively  solid 
and  often  columnar  in  structure.  The  outside  lavas  of  the  mountain  which  have  been 
ejected  through  fissures  have  no  such  crust,  but  sometimes  a  solid  glassy  exterior  of  a 
fourth  to  half  of  an  inch. 

Volcanic  glass  usually  contains  moisture  enough  for  making  it  a  light  scoria  when 
it  is  heated  to  fusion  before  the  blowpipe,  as  shown  by  J.  W.  Judd  (1886),  and  also  by 
Iddings,  in  the  case  of  the  Yellowstone  Park  obsidian. 

(c)  Rupturing  and  other  effects  from  expansive  action.  —  Vapors  may  also 
produce  fractures  in  the  walls  of  craters  or  in  the  sides  of  the  volcanic 
mountain  by  their  sudden  generation  within  regions  about  or  beneath  the 
crater,  and  also  by  their  slow  accumulation  within  confined  spaces,  and  thus 
may  occasion  volcanic  eruptions.     They  produce  the  most  violent  projectile 
effects  when  water  in  large  quantity  gains  direct  access  to  the  lava-conduit ; 
for  the  conditions  are  then  those  that  cause  the  most  violent  of  boiler-explo- 
sions, except  that  they  are  on  a  scale  as  much  greater  as  the  volcano  is 
larger  than  a  boiler. 

Vapors  also  bring  pressure  to  bear  on  surfaces  of  liquid  lava  beneath 
them,  and  force  the  lava  up  fissures  to  levels  hundreds  of  feet  above  the 
bottom  of  a  crater. 

The  vapors  are  thus  the  chief  source  of  power  in  the  volcano.  They  may 
work  quietly,  but  they  are  at  the  bottom  of  all  violent  work. 

(d)  Vapors  of  deep-seated  origin.  — While   all   the   ordinary  projectile 
work  of  volcanoes  may  be  carried  forward  by  vapors  from  waters  that  gain 
access  from  the  sea,  or  the  fresh  waters  of  the  land,  it  is  a  question  whether 
vapors  from  the.  deep-seated  source  of  volcanic  action  may  not  have  aided 
explosively  the  first  opening  of   the  volcano.     The  lifting  action  of   the 
ascensive  force  in  Kilauea  is  so  quiet,  and  its  progress  so  slow,  —  400  feet 
at  the  most  in  six  years,  —  that  we  have  no  favorable  answer  from  this 
source.     Daubree  has  experimented  on  the  effects  of  steam,  driven  under, 
high  pressure  along  a  fracture  in  blocks  of  granite,  and  proved  the  efficiency 
of  such  a  course  in  making  a  tubular  passage  through  it.     The  results  are 
published   in  a  volume   entitled,   Les   Regions  invisibles  du   Globe   et  des 
Espaces  celestes,  1892,  and  in  earlier  papers  read  before  the  French  Academy. 

The  occurrence  of  volcanoes  in  long  lines  implies  dependence  as  to  origin  on  great 
fractures,  and  mutual  dependence  of  the  volcanoes  along  any  such  line.  The  lines  are 
often  in  parallel  ranges  or  series  of  fissures,  and  must  have  opened  through  the  earth's  crust 
to  the  depths  that  supplied  the  melted  rock.  In  some  cases  the  volcanic  action  along  such 
lines  has  continued  longer  at  one  end  of  the  line,  or  of  the  several  lines  in  a  series,  than 
at  the  opposite  end,  and  extinction  has  been  in  like  manner  serial.  An  example  is  afforded 
by  the  Hawaiian  group.  The  group,  now  so  called,  is  about  400  miles  long  and  west- 
northwest  in  trend.  The  islands  consist  either  of  a  single  volcano,  or  of  two  or  more 
united.  The  prominent  doublets  are  Oahu  and  Maui ;  and  Hawaii  is  a  quintuplet,  in  two 
lines.  The  map  of  Maui,  on  page  179,  shows  plainly  by  the  aged  appearance  of  its  erosion 
over  west  Maui,  that  this  western  of  the  two  volcanoes  long  since  became  extinct,  while 
east  Maui  has  the  smooth  face  of  youth  and  may  have  been  active  within  two  or  three 
centuries.  There  is  the  same  evidence  that  west  Oahu  was  extinct  long  before  east  Oahu, 


HEAT.  283 

as  shown  on  the  map,  page  292,  and  that  Kauai,  the  western  island  of  the  group,  was  one 
of  the  earliest,  if  not  the  earliest,  to  become  inactive. 

But  Hawaii,  the  easternmost,  is,  on  the  contrary,  the  island  of  most  recent  activity. 
Here  are  the  active  volcanoes.  Further,  the  northwestern  and  the  northern  volcanoes  of 
Hawaii  were  the  first  to  become  extinct.  The  largest  and  highest  volcanic  island  of  the 
whole  group  is  Hawaii,  that  on  which  action  has  continued  the  longest.  In  the  Samoa 
group,  south  of  the  equator,  the  order  of  extinction  was  the  reverse  of  that  at  the  Hawaiian, 
or  from  east  to  west  —  Savaii,  at  the  west  end,  a  broad  and  lofty  cone  of  lavas  recent  in 
aspect,  answering  geologically  to  its  (dialectic)  namesake,  Hawaii,  of  the  Hawaiian  group. 

4.  Other  methods  of  work  in  a  volcano.  — Besides  the  action  of  vapors,  there 
are  contractional  effects  from  heat,  exhibited  in  columnar  forms,  and  irregular 
fracturing ;  for  each  lava-stream  has  cooled  down  from  a  temperature  above 
2000°  F.     There  are  fusing  effects ;  often  a  remelting  of  the  lavas  of  a  lake 
that  had  become  solidified ;  and  a  fusing  also  of  floating  masses  in  the  lakes  ; 
and  sometimes  an  extending  of  the  bounds  of  a  lava-lake,  or  an  opening  of 
new  lakes. 

There  are  also  large  bulgings  made  in  a  lava-stream,  while  it  is  cooling, 
through  the  vapors  that  are  generated  from  moisture  underneath  it. 

There  is  also  hydrostatic  and  other  gravitational  pressure  arising  from' 
the  height  of  the  lava-column  in  a  lava-lake,  or  in  the  mountain. 

5.  Eruptions.  —  (a)  Preparation  for  an  eruption.  —  The  crater,  as  at  Vesu- 
vius or  Hawaii,  after  it  has  been  emptied  by  a  great  discharge  at  a  time  of 
eruption,  often  has,  at  first,  a  period  of  apparently  extinguished  fires,  and 
something  like  the  conditions  of  an  incipient  solfatara  in  the  lazy  escape 
of  vapors  from  the  fissures  and  the  lining  of  fissures  with  sulphur  crystals. 
Next,  little  outflows  of  lava  take  place  from  apertures  or  fissures  in  some 
part  of  the  bottom  or  floor  of  the  crater,  or  driblets  of  lava  or  jets  of  cinders 
build  a  small  cone  about  a  vent.     In  the  case  of  basaltic  lavas,  pools  of  boil- 
ing lava  often  appear  in  the  crater,  which  frequently  overflow  and  spread 
lava-streams  over  the  floor,  thus  making  small  eruptions.     In  the  case  of  the 
less  liquid  lavas  the  ejections  at  the  bottom  of  the  crater  are  mostly  of 
cinders,  and  one  or  more  cinder-cones  are  made  thereby  over  the  bottom ; 
but  now  and  then  escapes  of  lava  take  place  through  fissures.     The  process 
is  one  that  puts  new  material  over  the  bottom  of  the  crater  and  raises  its 
level;  and  it  goes  on  at  an  increasing  rate  until  the  eruption  commences. 
In  Kilauea,  such  overflows  from  the  large  lava-lake  may  have  a  length  of 
two  miles  on  the  floor  of  the  crater. 

But  this  raising  of  the  bottom  by  overflows  and  deposits  of  cinders  is 
accompanied  by  another  action, — the  upward  thrust  of  the  lavas  of  the  lava- 
column  through  the  ascensive  action  already  mentioned.  Owing  (1)  to  this 
lifting  action,  and  (2)  to  the  ejections,  the  solid  floor  of  the  crater  keeps 
rising ;  and  sometimes,  perhaps  generally,  the  larger  part  of  the  floor  is 
lifted  or  shoved  up  bodily  by  the  lavas  from  the  lava-column  that  are  forced 
in  beneath  it.  After  the  eruption  of  1840,  the  floor  of  Kilauea  was  raised 
bodily  between  300  and  400  feet  before  a  new  eruption  took  place.  By  the 


284  DYNAMICAL   GEOLOGY. 

same  methods,  the  floor  in  a  volcano  like  Vesuvius  may  be  raised,  preparatory 
for  another  eruption. 

This  principle  in  volcanic  science,  first  made  out  by  C.  S.  Lyman,  is  established  by 
facts  observed  by  him  on  Hawaii.  In  May,  1840,  an  eruption  emptied  the  crater  of  Kilauea, 
and  left  it  with  two  thirds  of  the  floor  sunken  nearly  400  feet  below  the  level  which  it  had 
just  before  the  eruption.  (This  was  6  months  before  the  author's  first  visit  to  the  crater.) 
Fig.  245  is  a  transverse  section  of  the  crater  as  it  was  after  the  eruption,  wo,  o'  m  being  the 
opposite  walls,  and  np,  p'n1  the  sunken  central  region  or  "  lower  pit."  Six  months  later, 

245. 


Vertical  section  of  crater  of  Kilauea  in  1840.    D.  '49. 

the  walls  of  the  lower  pit,  which  were  then  360  feet  high,  had  a  talus  of  broken  lava  along- 
side, falls  of  the  rocks  being  frequent  at  the  time.  In  1846,  C.  S.  Lyman  found  the  lower 
pit  of  the  crater  obliterated,  and  the  talus,  at  the  foot  of  its  walls,  constituting  a  ridge 
100  to  1 50  feet  high.  Its  floor  had  been  raised  as  a  whole,  with  the  talus  of  lava-blocks 
•upon  it ;  and  fault-planes  made  in  the  sinking  of  the  floor  at  the  eruption  in  1840  were 
those  used  in  the  rise.  This  ridge  was  gradually  buried  by  the  outflow  of  lavas  over  the 
floor,  but  it  still  existed  in  1864,  as  shown  in  the  view  of  Kilauea  on  page  270,  and  also 
in  a  map  of  the  crater  of  that  date  by  W.  T.  Brigham. 

At  times  of  approaching  eruption,  the  heat  and  projectile  action  of  the 
crater  become  intense.  The  heat  may  be  expended,  as  in  Kilauea,  in  multi- 
plying lava-lakes  for  ebullition  and  raising  blowing-cones,  or,  on  the  other 
hand,  as  in  Vesuvius,  in  projecting  cinders  to  enormous  heights  besides  start- 
ing some  lava-flows. 

(b)  The  eruption.  —  The  eruption  begins  after  the  lavas  have  risen  within 
the  crater  up  to  what  may  be  called  high-lava  mark ;  and  when  the  pressure 
from  the  vapors  generated  and  confined  below  and  from  the  hydrostatic  pres- 
sure of  the  lava-column  —  chiefly  the  former  —  is  too  great  to  be  withstood 
by  the  containing  mountain.  The  mountain  consequently  breaks ;  the  con^ 
duit  is  rent  open  on  one  side  or  the  other,  and  the  lavas  run  out.  If  the 
mountain  were  too  strong  to  break,  as  it  perhaps  is  in  the  earlier  part  of  its 
history,  when  it  is  of  little  height,  the  lava  would  rise  to  the  top  of  the  crater 
by  the  methods  described,  and  overflow  from  the  summit  on  this  side  or  that. 
But  modern  eruptions,  as  has  been  stated,  are  usually  through  fissures. 

The  discharge  of  the  lavas  empties  the  upper  part  of  the  lava-conduit  or 
lowers  the  level  of  its  upper  surface,  and  undermines  the  lifted  crater-floor  ; 
and  the  result  may  be  (1)  a  collapse  or  down-plunge  of  the  floor  within  the 
crater,  making  again  a  pit  hundreds  of  feet  deep,  or  1000,  or  2000,  as  the  case 
may  be ;  and  (2)  sometimes  also  a  down-plunge  of  the  walls  of  the  crater. 

Part  of  the  undermining  at  Vesuvius  is  due  to  outflow  of  lavas,  part  to 
discharge  of  volcanic  cinders ;  but  at  basaltic  Kilauea,  it  all  comes,  ordinarily, 
from  the  escape  of  liquid  lavas. 


HEAT. 


285 


At  the  eruption  of  Kilauea  in  1840,  the  first  signal  to  the  natives  on  the 
coast  was  not  an  earthquake,  but  a  "  fire  in  the  woods."  As  a  consequence 
of  the  action,  six  miles  to  the  east  a  fissure  opened,  and  some  lavas 
escaped ;  in  the  next  seven  miles  there  were  other  fissures,  giving  out  steam 
and  making  small  patches  of  lava.  Finally,  10  miles  from  the  sea  and  27 

246. 


Three  cinder-cones  of  1840,  on  the  seashore  south  of  Nanawale.    D.  '49. 

miles  from  Kilauea,  at  a  height  of  1250  feet  above  tide  level,  an  outflow 
began  from  fissures  which  continued  till  it  reached  the  sea,  where  there  was 
a  violent  conflict  of  the  hot  lavas  and  water,  and  three  cinder-cones  were 
made,  each  probably  over  a  separate  fissure.  The  lavas  in  the  crater  at  the 
same  time  sunk,  as  has  been  stated,  nearly  400  feet  in  consequence  of  the 
outflow. 

The  following  diagram  (the  height  relatively  much  exaggerated)  shows 
the  change  in  depth  of  Kilauea  (according  to  the  best  reports),  in  several 
great  eruptions,  commencing  with  that  of  1823.  In  1823,  before  the  erup- 

247. 


1832 


Sections  of  Kilauea  at  different  periods. 

tion,  the  whole  depth  of  the  crater  was  800  to  1000  feet ;  at  the  eruption, 
nearly  the  whole  bottom  sunk  down  to  the  level  ab,  or  600  to  800  feet, 
making  the  depth  of  Kilauea  over  this  deeper,  central  part  about  1500  feet. 

In  1832,  the  depth  before  the  eruption  was  700  feet ;  after  it,  the  center  sunk  to  a'&', 
making  the  depth  1150  feet ;  in  1840,  the  depth  of  the  sinking  was  between  360  and  400 
feet.  Six  years  afterward,  the  lower  pit  was  obliterated,  reducing  the  depth  of  Kilauea 
to  only  600  feet.  It  sunk  again  at  an  eruption  in  1868.  It  is  now  only  480  feet  deep 
where  deepest  near  the  northeastern  walls,  and  less  than  400  feet  at  the  center. 

At  the  last  two  of  the  eruptions,  those  of  1887  and  1891,  the  only  sinking  of  the  bottom 
that  took  place  was  within  the  great  lake-basin  called  Halemaumau  —  half  a  mile  in  diameter 
—  in  the  southwestern  part  of  the  crater.  The  map  of  the  crater,  Fig.  230,  shows  its 
condition  immediately  after  the  eruption  of  1886,  with  the  lake-basin  empty  to  its  bottom, 
900  feet  below  the  level  at  the  Volcano  House,  and  nearly  600  below  the  rim  of  the  basin. 
(Emerson.)  The  walls  of  the  basin  began  at  once  to  fall,  and  in  six  months  the  condi- 
tion was  that  represented  in  the  adjoining  figure  231.  The  basin  contained  a  debris-cone 
made  of  the  fallen  blocks,  and  not  at  all  of  ejected  material ;  and  the  progress  afterward 


286  DYNAMICAL   GEOLOGY. 

soon  made  it  evident  that  it  was  produced  out  of  the  falling  blocks  by  the  lifting  of  the 
bottom  owing  to  the  ascensive  action  of  the  lavas  beneath,  like  Lyman's  ridge  described 
on  page  284.  (F.  S.  Dodge.) 

The  recent  eruptions  of  Mount  Loa,  the  summit  crater,  have  been  vastly 
more  extensive  than  those  of  Kilauea.  Situated  topographically  within  the 
same  mountain  mass,  as  the  following  diagram  (Fig.  248)  shows,  the  two 
have  yet  gone  on  with  their  preparations  and  eruptions  simultaneously,  but 
in  general  independently ;  the  loftier  crater  unaffected  in  its  lifting  and  its 
eruptive  forces  by  the  great  opening  at  the  lower  level.  Kilauea  has  none  of 
the  virtues  of  a  safty-valve  for  Mount  Loa,  though  probably  as  much  of  a 
safety-valve  for  the  mountain  as  any  volcanic  vent  ever  is.  The  recent  erup- 
tions of  Mount  Loa  occurred  in  the  years  1843,  1852,  1855,  1859,  1868,  1880, 
1887 ;  and  excepting  the  two  on  the  southern  slopes,  those  of  1868  and  1887, 
the  place  of  outbreak  was  at  heights  of  10,500  to  13,000  feet,  and  the  lengths 
of  the  streams  20  to  35  miles.  At  the  place  of  outbreak  in  several  in- 
stances, there  have  been  great  fountains  of  lava,  300  to  700  feet  in  height, 


Section  of  Mount  Loa  and  Kilauea. 

that  played  for  a  few  days,  as  the  stream  gushed  forth  —  a  consequence 
either  of  the  projectile  force  of  escaping  vapors,  or  of  hydrostatic  pressure 
from  the  lavas  in  the  Mount  Loa  lava-column,  or  from  both  causes  combined. 
In  contrast  with  Mount  Loa,  the  famous  Hecla  of  Iceland,  about  5000  feet 
in  height,  has  had  only  five  eruptions  since  1700,  viz.,  in  1728,  1754,  1766, 
1845,  1878. 

(c)  Earthquakes  not  an  essential  feature  of  volcanic  eruptions.  —  The  great 
eruptions  of  Mount  Loa,  excepting  those  of  1868  and  1887,  have  been  unat- 
tended by  noticeable  earthquakes.  The  rupturings  must  have  caused  vibra- 
tions, but  they  have  usually  been  unperceived  at  the  villages  of  the  island. 
"A  fire  on  the  mountain"  has  been  the  first  announcement  of  the  outbreak. 
When  the  outflow  has  begun,  the  liquid  lava  in  the  bottom  of  the  summit 
crater  has  disappeared,  and  the  crater  has  lost  at  the  same  time  its  activity. 

In  1868  and  1887,  however,  there  were  violent  earthquakes  ;  but  otherwise  the  circum- 
stances were  not  different.  In  1887,  two  days  intervened  between  the  appearance  and 
fading  of  the  light  at  the  summit  and  the  exit  of  the  lavas,  and,  in  1868,  four  days,  owing 
apparently  to  the  distance  of  the  place  from  the  discharging  conduit ;  but  when  once  out 
the  lavas  rose  into  a  fountain  of  100  to  200  feet,  showing  that  they  were  under  great 
pressure,  and  then  the  shakings  ceased.  At  the  eruption  of  1868,  Kilauea  was  discharged 
at  the  same  time  as  Mount  Loa,  —  Mount  Loa  forces  evidently  producing  this  remark- 
able result  by  breaking  first  the  Mount  Loa  conduit,  and  then  four  days  later,  before  the 
earthquakes  ceased,  that  of  Kilauea.  In  other  words,  the  fracturing  of  the  mountain  made 
by  vapors  generated  by  the  Mount  Loa  fires  finally  extended  to  the  Kilauea  conduits. 


HEAT. 


287 


The  eruptions  of  Vesuvius  are  generally  heralded  by  earthquakes.  The 
ejected  lavas  commonly  bear  evidence,  in  the  various  chlorides  among  the 
ingredients  deposited  by  vapors  on  the  lavas,  that  the  waters  of  the  sea  had 
gained  access  to  the  fires.  The  accompanying  projection  of  cinders  is  often 
to  great  heights,  and  over  a  wide  reach  of  country.  Those  of  1779,  according 
to  Sir  William  Hamilton,  were  thrown  to  a  height  of  10,000  feet. 

The  sketch  of  Vesuvius  in  Fig.  225,  page  266,  represents  its  condition  a  few  weeks 
before  an  eruption,  when  the  crater  was  filled  to  the  summit  plain  there  shown,  and  a 
cinder-cone  on  this  plain  (see  sketch)  was  the  most  active  feature  ;  but  there  was  a  slug- 
gish stream  of  lava  in  the  summit  plain,  and  red  heat  was  visible  a  foot  down  in  cracks. 
The  eruption,  as  described  by  Abich,  took  place  in  August,  1834 ;  two  streams  of  lava 
flowed  out,  the  chief  one  from  the  base  of  the  old  cone,  and  it  was  accompanied  by  flames, 
which,  according  to  Abich,  were  produced  by  hydrogen  ;  it  was  half  a  mile  wide,  18  to  30 
feet  deep,  and  9  miles  long.  It  engulfed  the  village  of  Caporeco,  sparing  only  4  houses 
out  of  500.  The  old  cone  was  laid  open  by  the  eruption,  and  the  top  plain,  that  was  the 
floor  walked  over  by  the  author,  had  sunk  into  a  deep  abyss.  (Abich,  Vues  Illustr. 
sur  le  Vesuve  et  VEtna,  Berlin,  1837.) 

6.  Lava-streams.  —  (a)  Their  general  characteristics.  —  Lava-streams  sel- 
dom make  more  than  three  miles  of  flow  a  day,  and  sometimes  take  a  year 
for  30  miles.  This  is  true  even  of  the  basaltic  kinds.  They  flow  rapidly 
when  unobstructed,  but  often  become  dammed  by  coolings,  especially  at 
the  frequent  interruptions.  As  the  stream  of  basaltic  lava  moves,  it  be- 
comes crusted  over  its  exterior  surface,  and  then  flows  on  in  the  lava-tunnel 
so  made,  which,  at  the  end,  it  may  leave  empty.  Owing  to  the  obstruc- 
tions, the  lavas  often  break  their  bounds,  and  one  stream  becomes  piled 
over  another.  The  surface  of  the  stream  has  ropy  lines  and  other  marks 


249. 


View  of  the  aa  lava-stream,  with  a  "  bomb,"  a,  10  feet  in  breadth  upon  it.    D.  '87. 

made  by  the  flowing  movement.  This  ordinary  lava  is  called  by  the 
Hawaiians  pahoehoe,  alluding  to  a  relatively  smooth  and  shining  or  satin- 
like  luster.  Another  kind,  the  aa,  into  which  the  pahoehoe  sometimes 
abruptly  changes,  shows  over  its  surface  no  evidence  of  flow;  the  stream 
consists  of  broken,  ragged  masses,  large  and  small,  bristled  all  over  with 
points  (Fig.  249);  and,  owing  to  the  masses  being  piled  loosely  together,  the 


288 


DYNAMICAL   GEOLOGY. 


field  of  aa  is  usually  20  to  30  feet  higher  in  level  than  that  of  pahoehoe. 
The  breaking  up  is  produced  while  the  stream  is  slowly  moving.  Some 
cause,  acting  beneath,  half  chills  the  mass,  and  the  lava,  thus  rendered 
brittle,  is  readily  broken  during  the  movement.  The  only  cause  of  such 
cooling  appears  to  be  the  vaporizing  of  subterranean  waters  flowed  over  by 
the  hot  lava-stream. 

All  lavas  crust  over  readily,  and  then  are  slow  in  further  consolidation, 
owing  to  the  rock  being  a  very  poor  conductor  of  heat. 

The  texture  depends  on  rate  of  cooling,  —  the  most  rapid  rate  producing 
glass,  —  glassy  crusts  in  the  case  of  basaltic  lavas,  and  massive  glass  in 
trachytic  regions.  Ordinary  cooling  ending  in  an  indistinct  or  fine  crystal- 
line texture ;  and  from  this,  there  may  be  all  grades  in  the  same  mass  or 
thick  stream,  up  to  a  true  granite-like  structure,  as  shown  by  Judd  (1874), 
Hague  and  Iddings  (1885),  and  as  indicated  by  the  author  in  1849.  Judd 
.establishes,  through  facts  from  the  Western  Isles  of  Scotland,  that  in  a  single 
area  a  volcanic  rock  may  vary  in  texture  from  a  glassy  lava  to  a  rock  of 
granitoid  structure,  both  among  basaltic  and  feldspathic  lavas. 


250-256. 


Figs.  250-253,  Feathery  forms  of  pyroxene  and  feldspar;  Figs.  254-256,  Microlites  — all  of  Mount  Loa  lavas. 

E.  S.  Dana,  '88. 

Through  some  method  of  change,  perhaps  an  alternation  of  melting  and 
cooling,  the  fine  basalt  of  Mount  Loa  and  Kilauea  often  has  the  pyroxene 
and  feldspar  in  feathery  tufts,  like  common  forms  of  frost  on  windows. 
(Figs.  250-256.)  "The  feldspar  needles  lie  parallel  with  the  pyroxene 


HEAT.  289 

fibers,  as  if  on  crystallizing  in  these  dendritic  forms  the  latter  mineral  had 
drawn  the  feldspar  into  parallel  position  with  it."  Fig.  253  represents  the 
facts  well,  as  the  feldspar  crystals  are  larger  than  usual.  Fig.  252  shows 
one  large  ordinary  crystal  of  pyroxene  below  the  tuft.  Figs.  254-256  repre- 
sent some  of  the  microlites  in  the  basalt-glass  of  the  region.  (E.  S.  D.,  1888.) 

In  the  consolidation  of  igneous  rocks  a  more  decided  concretionary  structure  some- 
times results.  This  is  especially  true  of  glassy  or  semi-glassy  kinds,  which  often  contain 
spherulites,  having  more  or  less  distinctly  a  radiately  fibrous  structure.  Spherulites  appear 
to  differ  little  from  the  radiate  concretionary  forms  common  in  manufactured  glass  which 
has  been  artificially  devitrified.  (Rutley,  1890.)  Some  spherulites  are  in  part  separated 
peripherally  from  the  inclosing  glass,  as  if  formed  within  "  lithophyses "  or  vesicles. 
(Iddings,  1888.)  See  page  337,  beyond,  under  Metamorphism.  A  concretionary  form  in 
dioryte  is  represented  on  page  97. 

(b)  Volcanic  bombs.  —  Volcanic  bombs  are  roundish  or  ovoid  masses  of 
lava,  concentric  in  structure.     They  sometimes  have  a  center  of  chrysolite, 
or  of  the  more  scoriaceous  lava.     They  occur  on  Hawaii  in  connection  with 
the  aa,  and  are  of  various  sizes,  from  one  inch  to  ten  feet  or  more  in  diameter. 
They  are  produced  on  Hawaii  by  the  rolling  movement  of  the  front  of  the 
stream  due  to  friction  at  bottom.     It  is  possible  that  the  same  kind  of  move- 
ment in  the  ordinary  lava-stream  may  produce  them ;  but  on  Hawaii  they  are 
found  only  in  aa  lava-fields  ;  one  is  shown  in  Fig.  249  at  a.     Johnston-Lavis 
gives  essentially  the  same  general  explanation  of  the  origin  of  some  bombs 
observed  by  him  about  Vesuvius.     The  bombs  of  the  Eifel  region,  in  many 
of  which  chrysolite  makes  the  center,  have  been  supposed  to  be  projected 
bombs;  but  in  view  of  the  above  facts  this  may  be  questioned.     Projected 
blocks  of  ordinary  lava  are  not  bombs,  but  merely  projected  blocks. 

(c)  The- opening  of  subordinate  or  lateral  volcanic  cones.  —  Cones  of  erup- 
tion often  form  over  fissures  during  the  progress  of  an  eruption  from  the 
fissure.     Each  such  cone,  when  it  is  in  progress,  has  its  own  lava-conduit,  as 
a  branch  from  the  general  lava-conduit  of  the  mountain.     But  it  is  relatively 
small,  and  its  liquid  lavas  consequently  may  soon  become  chilled  by  the 
cold  rocks  about  it;  and  hence  such  lateral  or  subordinate  volcanoes  have 
usually  a  brief  existence.      They,  however,  often  work  hard  during  their 
short  life,  and  even  in  two  or  three  weeks  may  make  a  cone  many  hundred 
feet  in  height. 

Such  cones  occur  about  the  sources  of  great  eruptions ;  but  they  are  most 
common  near  the  seashore,  where  subterranean  fresh  waters  most  abound 
for  the  supply  of  moisture,  and  where  the  sea  is  at  hand  as  another 
source.  They  may  be  either  cinder-cones  or  tufa-cones,  but  are  most 
likely  to  be  the  latter  if  near  the  seashore.  The  volcanic  origin  of  such 
cones  can  be  proved  by  the  pericentric  arrangement  of  the  materials  con- 
stituting them.  The  sea,  with  its  broad  waves  and  the  aiding  winds,  can 
make  heaps  or  ridges  out  of  the  sands  existing  or  produced  on  its  borders, 
but  it  cannot  arrange  the  layers  of  sand  or  earth  pericentrically  into  a 
DANA'S  MANUAL — 19 


290  DYNAMICAL   GEOLOGY. 

conical  hill.  But  volcanic  cinders  or  ashes  are  often  carried  by  the  winds  to 
great  distances,  and  when  abundant,  make  extensive  deposits  with  horizontal 
bedding ;  and  such  deposits  may,  in  extreme  cases,  reach  a  thickness  of  hun- 
dreds of  feet  and  bury  forests. 

Where  small  cones  have  been  mostly  removed  to  their  base,  they  may 
show  a  central  cone  of  lava  — the  lava  that  in  its  active  state  was  the 
source  of  the  ashes,  and  around  it  more  or  less  of  the  ejected  ashes  or  lava. 
Such  places  have  been  called  "volcanic  necks." 

(d)  The  earlier  lava-streams  of  a  great  volcano  much  thicker  than  the  later. 
—  On  going  up  the  valleys  of  Tahiti  (Fig.  161),  the  thickness  of  the  lava- 
streams  was  found  by  the  author  to  increase  from  10,  20,  and  30  feet  along 
the  coast  to  500  and  1000  feet,  five  or  six  miles  in  the  interior  ;  and  in  Kauai, 
of  the  Hawaiian  group,  the  same  general  fact  proved  to  be  true.      These 
great  volcanoes  appear  to  have  poured  lavas  out  copiously  at  their  com- 
mencement, and  to  be  now  in  a  greatly  dwindled  condition.     In  what  geolog- 
ical period  the  Tahitian  and  Hawaiian  volcanoes  began  to  flow  is  unknown. 

(e)  The  interior  of  the  volcanic  mountain  before  and  after  extinction.  — In 
times  of  activity,  a  great  volcanic  mountain  has  within  it  a  column  of  liquid 
lavas,  the  lava-conduit,  which  may  be  two,  three,  or  more  miles  in  diameter. 
During  the  long  period  of  activity  the  heat  of  the  column  spreads  far  into 
the  adjacent  cooled  lavas,  occasioning  in  them  a  more  coarsely  crystalline 
condition  than  that  of  the  modern  lava-stream. 

At  the  extinction  of  the  volcano,  if  the  ascensive  force  continued  to  hold 
the  summit  of  the  lava-column  to  its  high  position,  the  enormous  liquid  mass 
would  have  cooled  with  extreme  slowness,  and  become  throughout  more  or 
less  crystalline.  The  nearly  vertical  face  of  the  central  peak  of  Tahiti,  3000 
feet  or  more  in  height,  as  seen  by  the  author  from  a  summit  near  by  (page 
180),  was  found  to  be  without  any  trace  of  layers;  it  was  just  such  a  con- 
tinuous mass  from  the  top  down,  as  the  cooling  of  a  lofty,  central  lava-mass 
would  have  made.  And  rounded  stones  of  a  coarsely  crystalline  granite 
rock,  found  along  the  bed  of  the  stream  six  to  eight  miles  up  one  of  the 
valleys,  appeared  to  be  evidence  as  to  the  crystalline  structure  of  the  central 
peak,  sustaining  the  principle  as  to  the  connection  of  grade  of  crystallization 
with  rate  of  cooling.  (D.,  1839.) 

Extinction  is  a  consequence  of  a  withdrawal  of  heat,  or  failure  of  the  ascensive  action. 
But  the  circumstances  attending  it  may  be  various.  A  general  collapse  or  down  plunge 
of  the  summit  at  the  eruption  may  leave  a  crater  2000  feet  deep,  as  in  the  case  of  Halea- 
kala  in  east  Maui,  or  a  collapse  may  fail  to  take  place  at  the  final  eruption,  through  a 
gradual  decline  of  heat  within,  and  the  mountain  hence  be  left  without  a  visible  crater,  as 
is  true  of  Mount  Kea.  E.  D.  Preston  has  proved,  by  gravity  determinations  with  the 
pendulum,  that  Haleakala  below  its  crater  is  solid,  the  gravity  found  being  2-7,  and  that 
Kea  in  its  upper  part,  giving  2-1,  is  hollow.  The  same  evidence  has  indicated  that  the 
volcanic  mountains  of  Ascension  Island,  St.  Helena,  and  Fujiyama  in  Japan,  are  hollow,  — 
densities  of  1-6,  1-9,  and  2-1  having  been  found  severally  for  the  masses  of  these  moun- 
tains ;  and  by  the  deviation  of  the  plumb-line  of  only  7  or  8  seconds  by  Chimborazo,  it  is 
believed  to  be  indicated  that  this  mountain  also  is  hollow.  Preston  obtained  for  the  lower 


HEAT.  291 

part  of  Mount  Kea  the  extraordinary  density  of  3-7,  for  which  volcanic  science  has  as  yet 
no  explanation. 

Haleakala  ended  its  work  in  throwing  up  over  the  bottom  of  the  great  crater  many 
cinder-cones  500'  to  900'  high,  and  Mount  Kea  gasped  out  its  life  in  making  similar  cones, 
but  as  summit  peaks. 

Extinction,  besides  being  due  to  a  downward  withdrawal  of  the  conduit  lava,  may 
take  place  in  consequence  of  the  cooling  of  these  lavas  from  the  outside,  when  in  contact 
with  the  solid  rocks.  The  supply  conduit  of  Kilauea  has  probably  been  as  large  in  cross 
sections  as  the  crater  (page  276)  ;  and  perhaps  much  larger,  this  being  suggested  by  an 
outside  range  of  bluffs  on  its  north  and  northeast  side.  It  may  be  as  large  now  ;  but  the 
confinement  of  the  recent  eruptions  to  the  basin,  Halemaumau,  in  its  southwestern  part, 
suggests  the  possibility  that  cooling  has  already  reduced  it  to  less  than  a  third  of  its  former 
size.  The  reduction  may,  however,  be  restricted  to  the  upper  portion  of  the  conduit ;  in 
which  case  it  may  regain  its  former  size  at  another  great  eruption.  At  Vesuvius,  the 
modern  active  cone  is  partly  surrounded  by  the  walls  of  a  former  crater,  of  far  wider 
extent,  called  Somma  ;  and  the  relative  sizes  of  the  modern  and  ancient  craters  probably 
indicate  the  amount  of  contraction  that  has  taken  place  in  the  lava-conduit.  Teneriffe 
and  some  other  large  volcanic  mountains  have  extensive  amphitheaters  marking  the  limits 
of  the  ancient  crater,  and  a  cone  of  relatively  small  size  within  it  representing  the  later 
condition  of  the  fires. 

7.  Explosive  eruptions.  —  Besides  the  ordinary  eruptions  above  described, 
there  may  be,  in  all  kinds  of  volcanoes,  true  explosive  eruptions.  The 
projectile  action  within  the  crater  in  such  an  eruption,  instead  of  ceasing 
at  the  commencement  of  a  discharge  of  the  lavas,  as  described  above, 
becomes  at  once  enormously  increased,  and  projectile  discharges  of  terrific 
violence  are  produced,  with  destructive  shakings,  violent  thunder  storms, 
and  copious  cinder-ejections  over  a  wide  reach  of  country.  The  stones 
thrown  out  are  often  of  great  size.  At  one  such  eruption  in  1883,  that  of 
Krakatoa,  an  island  off  western  Java,  the  finer  ashes  ascended  50,000  feet, 
and  are  supposed  to  have  been  carried  a,round  the  world,  and  to  have 
caused  the  red  sunset-glows  of  the  autumn  following.  The  end  came  as 
suddenly  as  the  beginning.  The  eruption  began  early  one  morning,  made 
day  into  night  by  its  gray  and  black  cinder-ejections,  and  left  the  sky  clear 
by  the  close  of  the  next  day.  No  outflow  of  lavas  took  place.  Another 
such  eruption  occurred  in  the  Tarawera  region,  New  Zealand,  in  1886. 
The  eruption  was  of  extreme  violence,  yet  it  was  ended,  and  the  ashen  sky 
cleared,  in  six  hours.  But  it  destroyed  villages  and  their  inhabitants,  and 
deluged  with  mud-eruptions  the  beautiful  geyser  terraces  of  the  region. 

Kilauea  had  such  an  eruption  in  1789  (or  about  that  time).  The  borders 
of  the  crater  for  one  to  two  miles  in  breadth,  especially  to  the  south  and 
southwest,  are  covered  with  the  blocks  of  lava  (some  of  100  cubic  feet), 
scoria,  and  ashes  of  the  eruption,  and  a  larger  region  with  the  finer  material. 

For  such  explosive  eruptions  water  in  large  volumes  must  gain  sudden 
access  to  the  interior  of  a  lava-conduit,  —  that  is,  to  the  liquid  lavas  of  the 
lava-column;  for  the  projectile  force  of  the  abruptly  generated  vapors  is 
enormous,  and  all  is  quick  work,  as  in  an  explosion.  The  stones  ordinarily 
come  up  from  the  throat  of  the  volcano,  the  region  of  hot  rocks ;  and  this 


292 


DYNAMICAL   GEOLOGY. 


origin  is  sometimes  proved  by  the  crystalline  structure  and  minerals  of  the 
rocks.  It  is  probable  that  other  islands  of  the  Hawaiian  group  have  suffered 
from  still  greater  explosions;  for,  as  the  accompanying  map  (Fig.  257)  shows, 
Oahu  consists  of  portions  of  two  mountain-cones.  The  larger  part  of  the 
eastern  cone  —  the  one  of  most  recent  extinction  —  must  have  been  broken  off 
and  sunk.  A  vertical  wall  over  20  miles  long  marks  the  course  of  the  fract- 
ure. Its  highest  point  is  over  3000  feet  high  after  long  exposure  to  denuda- 
tion. Molokai  bears  evidence  of  like  catastrophic  experience. 

The  conglomerates  made  by  volcanic  ejections  contain  angular  fragments, 
and  never  consist  chiefly  of  rounded  pebbles  or  stones. 


257. 


OAHU 

FROM  THE  -40- 

GOVERNMENT  MAP 

012346678 

36- 


Explosive  eruptions  of  another  kind,  which  might  be  styled  semi-volcanic, 
are  included  among  described  volcanic  phenomena.  In  such  eruptions  water 
in  large  volumes  gains  sudden  access  to  the  heated  depths  beneath  an  extinct 
or  nearly  extinct  volcanic  mountain  through  fractures  or  movements  along 
planes  of  weakness,  as  in  other  cases;  but  the  heated  depths  are  not  hot 
enough  for  fused  rocks.  The  consequences  are  earth-shakings ;  explosions 
from  the  suddenly  generated  steam ;  the  rending  of  rocks  in  the  deep- 
seated  region  of  the  explosions ;  projectile  action  throwing  the  stones  and 
great  rock-masses  so  made,  and  the  dust  from  abrasion,  into  the  air  and  over 
the  adjoining  region,  attended  by  vast  and  violent  effusions  of  steam, 
making  darkness  and  terrific  storms  about  the  mountain  ;  —  and  not  outflows 
of  lava  nor  the  projection  of  volcanic  ashes  and  scoria  from  cooled  lavas. 


HEAT.  293 

No  liquid  lavas  are  in  any  way  directly  concerned,  and  hence  the  eruptions 
are  only  semi-volcanic.     Their  violence  may  cease  in  a  few  hours. 

The  eruption  at  Bandai-san,  Japan,  in  July,  1888,  was  probably  of  this  kind.  The 
volcano  had  been  extinct  for  1000  years.  In  an  hour  after  it  burst  out  the  ash-shower 
had  mostly  passed,  the  pitchy  blackness  changing  so  soon  to  dim  twilight ;  and  in  5  hours 
all  was  ended.  Kikuchi,  who  describes  the  eruption,  states  that  no  evidence  appeared  that 
liquid  lavas  contributed  to  the  ejected  material,  or  to  any  of  the  results. 

The  blowing  off  of  the  summits  of  volcanoes  has  been  attributed  to  explosive  eruptions. 
Steam  has  little  expansive  power  after  it  escapes  into  the  open  air.  It  expends  its  energies 
in  work  where  generated,  as  in  a  steam-boiler.  Where  large  open  craters  exist,  the  volcanic 
peaks  about  it  would  be  little  moved  by  the  explosion,  except  through  undermining  and  a 
collapse.  But  if  the  old  mountain  had  been  much  denuded,  and  was  essentially  solid  to 
its  summit,  an  explosion  within  it  might  widely  scatter  the  fragments,  besides  making 
great  excavations  at  the  center.  The  stones  hurled  from  Bandai-san  are  said  to  have 
struck  the  trees,  on  descending,  at  an  angle  of  about  30°. 

4.   Work  of  the  Spent  Vapors  and  Waste  Heat  of  the  Volcano  :  Fumaroles, 

Ovens,  Solfataras. 

While  the  chief  part  of  the  spent  vapors  and  heat  of  the  volcano  go* 
directly  from  the  boiling  or  discharged  lavas  into  the  air,  a  portion  escapes 
through  fissures  about  a  volcano  or  a  volcanic  region.  They  thus  make 
(1)  fumaroles  (so  named  from  the  Latin  fumus,  smoke),  the  greater  number 
of  which  open  upward  directly  into  the  air,  but  some  into  cavernous  places 
in  the  crater  or  in  lava-streams ;  (2)  solfataras  (so  named  from  the  Italian 
solfo,  sulphur),  which  are  made  up  of  a  combination  of  steaming  fissures,  and 
cover  large  areas  with  the  results  of  decomposition  and  deposit  from  the 
escaping  gases.  Fumaroles  are  common  about  the  walls  of  active  craters 
and  the  courses  of  lava-streams,  and  the  escaping  vapors  may  have  all  tem- 
peratures from  nearly  that  of  the  liquid  lava  to  212°  F.  and  below.  But 
solfataras  are  usually  more  remote  from  the  center  of  volcanic  action,  and 
may  occupy  regions  of  long-quiet  or  essentially  extinct  craters ;  and  conse- 
quently the  vapors  have  a  lower  temperature. 

Vesuvius  has  its  fumaroles ;  but  the  solfatara  of  the  region  is  to  the  west 
of  Naples,  over  the  extinct  volcanic  region  of  the  Phlegraean  Fields.  Kilauea 
has  fumaroles  or  steaming  fissures  along  its  walls  and  some  of  large  size  just 
west  of  the  Volcano  House  ;  and  but  a  few  rods  northwest  of  the  same  house 
there  is  a  solfatara  region.  Both  fumaroles  and  solfataras  derive  accessions 
to  the  vapors  from  descending  vraters  supplied  by  rains,  and  some  of  the 
fissures  afford  only  odorless  steam. 

The  rocks  (solidified  lavas),  acted  upon  by  the  volcanic  vapors,  consist  mostly  of 
silica,  alumina,  potash,  soda,  lime,  magnesia,  and  iron  oxide ;  the  presence  of  potash 
with  little  or  no  soda  distinguishes  those  of  the  third  class  (p.  273),  and  the  near  absence 
of  potash,  those  of  the  second  and  first  classes. 

The  chief  vapor  or  gas  coming  directly  from  the  lavas  is,  in  all  volcanoes,  sulphurous 
acid  (S02);  and  with  it  may  be  hydrogen  and  nitrogen.  At  Vesuvius,  chlorine  is  given 


294 


DYNAMICAL  GEOLOGY. 


out,  which  becomes  hydrochloric  acid  as  it  leaves  the  liquid  lava,  and  is  evidence,  as  has 
been  stated,  that  sea  water  aids  in  the  action  of  that  volcano. 

Through  the  sulphurous  acid  (S02),  sulphur  and  various  sulphates  are  made;  e.g., 
alums  by  combination  of  sulphuric  acid  (SO3)  with  alumina  and  potash  or  soda ;  and 


259 


261 


Lava  stalactites :  Figs.  258-260  ( J) ;  261,  stalagmite  (J) ;  262, 
263,  portions  showing  exterior  surface  (i{) ;  264,  265,  sections, 
showing  inside  cavities;  266,  transverse  section  (4).  E.  S.  Dana. 

gypsum  (CaO.S03  +  2  aq)  by  combination  with  the 
lime,  as  well  as  Glauber  salt  or  sodium  sulphate 
(Na^O.  SO3.  10  aq)  by  combination  with  the  soda; 
and  also  potassium  sulphate  (K2O.S03)  by  combina- 
tion with  the  potash.  Glauber  salt  and  gypsum  are 
common  about  the  f  umaroles  and  in  the  caverns  of  the 
crater  and  lava-streams  of  Hawaii,  and  the  aluminum 
salts  or  alums  with  some  gypsum,  at  Vesuvius. 

Besides  these,  numerous  chlorides  occur  in  the 
Vesuvian  f  umaroles  ;  e.g.,  common  salt  or  sodium 
chloride  (NaCl),  iron  chloride  (FeCl3),  and  potassium, 
ammonium,  copper,  nlanganese,  and  other  chlorides. 

Magnetite  (Fe304)  and  hematite  (Fe203)  are  also 
f  umarole  products.  At  Vesuvius  the  crystals  of  these 
iron  oxides  are  attributed  to  the  reaction  of  the  steam 
on  the  iron  chloride.  Deville  and  Fouque1  also  report 
hydrogen  and  hydrocarbon  gas  as  given  out  at  Torre 
del  Greco  in  1861.  The  hydrocarbon  gas  could  well 
come  from  organic  materials  taken  in  with  the  sea 
water. 


HEAT.  295 

The  destruction  of  fissured  lavas  goes  on  in  connection  with  the  action  of  steam  and 
other  volcanic  vapors  ;  and  in  solfataras  the  rocks  become  reduced  over  large  areas,  to 
whitish  and  yellowish  earth,  passing  to  red  from  the  presence  of  iron  oxide.  Silica  is,  to 
some  extent,  set  free  ;  orthoclase  is  reduced  to  kaolin  ;  and  nearly  all  the  mineral  species 
present  are  decomposed. 

On  Hawaii,  the  effects  of  spent  vapors  have  their  climax  in  the  empty 
tunnels  made  by  a  flowing  lava-stream  (page  287),  in  which  the  liquid  lavas, 
as  they  vacate  the  tunnels,  leave  vapors  that  have  at  first  the  extremely 
high  temperature  of  the  lavas.  These  tunnel-like  caves  in  the  lava-stream 
of  1880-81,  near  Hilo,  are  hung  in  places  with  slender  lava  stalactites  10  to 
30  inches  long  (Figs.  258-260,  1  natural  size),  each  having  its  stalagmite 
(Fig.  261)  below  it;  and  they  consist  of  the  same  material  as  the  lava 
(labradorite  and  augite),  in  the  same  rock-like  condition,  and  also  have 
crystals  of  these  minerals,  and  of  magnetite  and  hematite,  in  their  many 
cavities.  The  chrysolite  is  the  only  mineral  omitted  in  this  remaking  of 
basalt  in  stalactitic  form  by  the  highly  heated  vapors.  (Similar  stalactites 
occur  also  in  Kilauea.)  Figs.  262,  263  represent  portions  of  stalactites  en- 
larged, showing  the  lines  of  growth  (?)  over  the  exterior,  and  264,  265,  the 
same  with  interior  cavities ;  Fig.  266,  a  section  of  a  stalactite  having  the 
usual  delicate  tabular  crystals  of  labradorite,  characterizing  basaltic  lava, 
with  augite  (the  clear  spots),  and  the  magnetite  in  dendritic  forms.  The 
figures  are  from  the  description  of  Hawaiian  rocks  by  E.  S.  Dana  in  the 
author's  work  on  volcanoes. 

5.    Distribution  of  Volcanoes. 

Volcanoes,  now  mostly  extinct,  occur  over  the  border-regions  of  the 
continents, — that  is,  the  regions  between  the  oceans  and  the  summit  of  the 
border-range  of  mountains,  as  between  the  Pacific  and  the  eastern  limit  of 
the  summits  of  the  Rocky  Mountains ;  in  the  continental  islands,  or  those 
near  seacoasts,  as  on  the  western  border  of  the  Pacific ;  in  oceanic  islands, 
nearly  all  of  which,  excepting  the  coral  islands,  are  throughout  volcanic,  — 
and  the  coral  islands  have  probably  a  volcanic  basis.  Volcanoes  are  most 
numerous  along  the  borders  of  the  larger  ocean,  the  Pacific,  —  the  mainland, 
or  the  islands  near  by,  abounding  in  them  on  the  east,  north,  and  west,  and, 
to  some  extent,  on  the  south  in  the  Antarctic  seas.  They  are  numerous  also 
in  the  seas  separating  the  northern  from  the  southern  continents,  namely, 
the  West  Indies,  between  North  and  South  America;  the  Mediterranean, 
between  Europe  and  Africa ;  the  Red  Sea,  between  Asia  and  Africa ;  the 
East  Indies,  between  Asia  and  Australia,  —  the  whole  together  making  a 
transverse  volcanic  belt  around  the  globe.  Few  exist  on  the  borders  of 
the  Atlantic,  and  these  few  in  the  West  Indies  and  in  the  Cameroons  Moun- 
tains on  the  coast  of  the  Gulf  of  Guinea.  Over  the  interior  of  continents, 
remote  from  the  regions  mentioned,  they  are  almost  unknown. 

1.  Over  the  Pacific.  — The  linear  arrangement  of  the  islands  of  the  Pacific,  explained 
on  page  39,  is  the  linear  arrangement  of  volcanoes.  Active  volcanoes  occur  in  the  Hawaiian 


296  DYNAMICAL   GEOLOGY. 

group,  of  the  north  Pacific ;  in  the  west  central  part  of  the  south  Pacific,  at  Tanna  and 
Ambry  in  of  the  New  Hebrides,  Tofua,  Lette  and  Amargura  of  the  Friendly  Islands,  and 
Tinacoro  in  the  Santa  Cruz  group ;  and  in  the  western  north  Pacific,  among  the  Ladrones. 

2.  Borders  of  the  Pacific. — Volcanoes  range  from  Fuegia  northward  at  intervals 
along  the  line  of  the  Andes  ;  32  of  them  in  Chile,  —that  of  Aconcagua,  23,000'  high  ;  7  or 
8  in  Bolivia  and  southern  Peru, — Arequipa,  18,877';  19  or  20  about  Quito,  nearly  all 
over  14,000'  ;  and  among  them  Chimborazo,  20,498' ;  Antisana,  18,880' ;  Cotopaxi, 
19,660  (by  barometer,  Dr.  Reiss,  19,613'  Whymper)  ;  Pichincha,  which  has  a  crater  2500' 
deep  and  1500'  wide  at  bottom.  Farther  north,  in  Central  America,  there  are  39,  about 
west-southwest  in  course,  and  beyond  is  another  line  of  7  large  cones  in  Mexico. 

In  California,  from  Lassens  Peak  in  the  northern  extremity  of  the  Sierra  Nevada,  or 
rather  the  southern  of  the  Cascade  Range,  a  grand  north  and  north-northwest  line  begins, 
containing  cones  10,000'  to  15,000'  in  height,  consisting,  as  described  in  1833  by  Hague 
and  Iddings,  of  andesyte,  dacyte,  and  basalt  lavas,  but  chiefly  of  the  former.  Lassens  Peak 
consists  mostly  of  dacyte  (quartz-andesyte),  but  with  some  quartz-basalt,  as  described  by 
Diller,  and  is  10,437'  high.  Mount  Shasta,  in  northern  California,  has  a  height  of  14,350' ; 
in  the  view  from  the  westward,  there  are  two  summits,  the  southern  the  principal  one. 
In  Oregon,  75  miles  north  of  Shasta,  stands  Mount  Pitt,  a  cone  9718'  high;  150  miles 
beyond,  Mount  Jefferson  ;  approaching  the  Columbia  River,  Mount  Hood,  11,225'  ;  and 
north  of  the  river,  Mount  St.  Helens,  about  12,000',  Mount  Adams,  9570',  Mount  Tacoma 
(or  Rainier),  14,444',  and  Mount  Baker,  10,755',  in  Washington.  Of  these,  Mount  Baker 
was  in  action  in  1843.  At  the  eastern  foot  of  the  Sierra  Nevada,  near  Lake  Mono,  are 
cones,  and  others  occur  on  the  plateau  region  of  Oregon,  Washington,  and  beyond. 

The  summit  of  the  Rocky  Mountains  has  also  its  volcanic  peaks,  and  among  them, 
in  the  Yellowstone  Park,  there  is  the  extinct  volcano,  Mount  Washburn,  to  the  north, 
9000'  high,  and  Mount  Sheridan,  to  the  south,  10,200'.  The  rocks  and  volcanoes  of  the 
Park  have  been  described  by  Hague  and  Iddings.  The  Spanish  Peaks  in  southeastern 
Colorado,  according  to  R.  C.  Hills,  are  laccolithic  cones,  instead  of  volcanic. 

Between  North  America  and  Asia  there  is  a  festoon  of  21  islands  with  volcanoes, 
in  the  Aleutian  Islands.  Along  the  Asiatic  coast  to  the  East  India  Islands,  there  are  15 
to  20  in  Kamchatka ;  13  in  the  Kuriles ;  25  to  30  in  the  Japan  group  ;  15  to  20  in  the 
Philippines ;  several  along  the  north  coast  of  New  Guinea  ;  and  a  number  in  New  Zealand. 
Far  south,  on  Antarctic  lands,  in  77°  46'  S.,  176°  45'  E.,  Mount  Erebus,  12,400'  high,  which, 
in  1842,  when  discovered  by  Captain  Ross,  sent  up  dense,  lighted  vapors  and  cinders  in 
successive  jets,  200'  to  300'  in  diameter,  to  a  height  above  the  crater  of  1500'  to  2000';  and, 
standing  near  it,  the  extinct  Mount  Terror,  10,900'  high.  South  of  Cape  Horn  there  are  the 
volcanoes  of  Deception  Island,  with  its  hot  lake,  and  Bridgeman's,  near  62 1°  S.,  in  the 
South  Shetlands. 

3.  In  the  Indian  Ocean.  —  A  few  volcanoes  exist  in  Madagascar ;  also  others,  on  the 
Isle  of  Bourbon,  Mauritius,  and  the  Comoro  Islands,  and,  to  the  south,  on  Kerguelen 
Land,  etc. 

4.  On  the  western   border  of  the   Indian    Ocean. — The  lofty  peak,   Kilima-Njaro, 
18,500',  near  3°  S.,  and  37'°  E.  is  volcanic;   also  Ruwenzori,  12,000'  to  13,000',  in  3° 
N.,  and  30^°  E.  ;  and  Mount  Gordon-Bennett,  just  south,  16,000'. 

5.  Over  the  seas  that  divide  the  northern  and  southern  continents  from  one  another, 
and  the  regions  in  their  vicinity. — Volcanoes  occur  in  (a)  the  West  Indies,  where  10 
islands  are  volcanic  ;  (&)  the  Mediterranean  and  on  its  borders,  as  in  Sicily  and  the  islands 
north,  Vesuvius,  and  other  parts  of  Italy  ;  Spain,  Germany,  etc.,  in  Europe  ;  the  Grecian 
Archipelago,  which  contains  5  volcanic  islands,  —  Santorin,  Milo,  Cimolos,  Polenos,  and 
Minyros ;  in  Asia  Minor,  where  are  the  Catacecaumene  and  other  volcanic  regions ;  and, 
more  to  the  eastward,  toward  the  Caspian,  Mount  Ararat,  16,950'  high  ;  Little  Ararat, 
12,800';  Demavend,  on  the  south  shore  of  the  Caspian,  21,77(3' ;   (c)  the  Red  Sea,  along 
its  southern  borders,  where  there  are  a  number  of  lofty  volcanic  summits ;  (cZ)  the  East 


HEAT.  297 

Indies,  where  there  are  200  or  more  volcanoes,  of  which  there  are  nearly  50  in  Java  alone 
(according  to  Dr.  Junghuhn),  and  28  out  of  the  50  now  active,  nearly  as  many  in  Suma- 
tra, 109  in  the  small  islands  near  Borneo,  and  a  number  in  the  Philippines,  etc. 

6.  On  the  borders  of  the  South  Atlantic.  — Only  in  the  Bight  of  Benin,  on  the  Afri- 
can coast,  where  a  volcano  in  the  Cameroons  Mountains  is  said  to  be  14,000'  high ;  and  on 
the  neighboring  islands,  from  Fernando  Po  to  Annabon. 

7.  On  the  borders  of  the  North  Atlantic.  —  None  on  the  western  north  of  the  West 
Indies.     On  the  eastern,  there  are  extinct  volcanoes  in  the  Auvergne  in    central  France, 
the  Eifel  in  Prussia,  and  of  past  geological  ages  in  Great  Britain. 

8.  In  the  Atlantic    Ocean.  —  St.    Helena,   Ascension,   Tristan   d'Acunha,   the    Cape 
Verd,  Canaries,  Madeira,  Azores,  Iceland,  and  Jan  Mayen  are  volcanic.    All  the  islands 
of  the  deep  part  of  the  ocean  (that  is,  not  on  the  European  or  American  borders)  are 
volcanic. 

The  number  of  active  volcanic  vents  in  the  world  is  about  300.  Of  these, 
five  sixths,  or  about  250,  are  within  or  on  the  border  of  the  Pacific  basin, 
there  being  about  148  on  the  continental  islands  between  New  Zealand  and 
Alaska,  45  on  the  borders  of  North  America  (Central  America  included), 
37  in  the  Andes,  and  20  on  Pacific  oceanic  islands.  Those  within  or  on  the 
borders  of  the  Atlantic  basin  are  39  in  number :  13  of  them  in  Iceland  or 
near  the  Arctic  circle,  3  in  the  Canary  Islands,  7  in  the  Mediterranean,  6  in 
the  Lesser  Antilles,  and  10  in  the  Atlantic  oceanic  islands.  The  Indian 
Ocean  contains  but  3,  and  the  Antarctic  Ocean  only  2,  so  far  as  now  known. 

The  proportion  of  active  volcanoes  to  the  total  number  in  volcanic 
regions  varies  indefinitely.  In  the  Hawaiian  group  it  is  about  1:5;  in 
the  Japan  Islands,  where  the  total  number  is  about  98,  the  ratio  is  1:3J; 
in  the  Kurile  Islands,  out  of  a  total  of  49  there  are  17. active;  in  the 
Marquesas,  Tahitian,  Samoan,  and  Fijian  groups  of  the  Pacific  all  are 
extinct. 

NON-VOLCANIC  IGNEOUS  ERUPTIONS. 

1.  General  description.  —  The  ejection  of  melted  rock  through  fissures, 
making  dikes  and  outflows,  is  essentially  the  same  in  result  whether  the 
ejections  are  due  to  distinctively  volcanic  action  or  to  11011- volcanic.  The. 
chief  difference  in  method  is  that  the  volcano  has  a  localized  center,  and  is 
pericentric  in  its  work ;  that  is,  it  has  a  crater  in  which  projectile  work  is 
carried  forward  at  intervals  between  eruptions,  whereas  a  non-volcanic 
ejection,  when  completed,  is  the  end  of  the  outside  work  until  a  new  and 
independent  fissure  is  opened.  Some  reference  to  a  center  in  the  general 
fracturing  may,  however,  be  a  fact  where  there  is  none  for  escaping  vapors. 
Commonly,  fissures  are  in  long  lines,  or  series  of  lines,  and  often,  also,  in 
approximately  parallel  series. 

For  the 'origin  of  large  deposits  of  volcanic  ashes  or  cinders,  it  is  most  probable  that 
there  has  been  a  center  of  activity ;  for  such  ejections  depend  on  escaping  gases,  rising 
and  exploding  in  ebullition  style,  and  for  this  kind  of  projectile  work  and  its  continuance 
long  enough  for  thick  beds,  one  or  more  centers  of  activity  appear  to  be  necessary.  The 
action  may  be  brief,  as  in  an  explosive  eruption.  Stones  rounded  by  wear  seldom  appear 


298  DYNAMICAL   GEOLOGY. 

among  such  projectile  material,  unless  water  has  aided  in  the  deposition.  Projectile 
work  throws  out  angular  fragments  broken  off  from  the  rocks  that  adjoin  the  vent.  If  the 
vent  ascends  through  non-volcanic  rocks,  fragments  of  these  rocks  may  be  distributed 
along  with  comminuted  igneous  material,  but  they  could  hardly  be  a  predominant  part  of 
the  mass. 

2.  Rocks.  —  The  rocks  of  non-volcanic  outflows  are  the  same  in  kinds 
with   those  of   volcanic   origin.     The   more   scoriaceous  lavas   are   usually 
absent,  but  vesicular  kinds  are  common.     The  moisture  producing  vesicula- 
tion,  and  sometimes  a  general  hydrous  condition  of  the  rock,  may  be  either 
that  of  the  deep-seated  igneous  source,  or  that  of  waters  taken  in  on  the  way 
to  the  surface;  for  the  latter  method  of  receiving  moisture,  —  that  by  molec- 
ular absorption,  if  a  principle  in  volcanic  phenomena  (page  278),  will  be 
as  much  so  in  non-volcanic.     Among  the  ejections  of  a  system  of  fissures, 
those  that  have  come  up  through  sedimentary  strata  may,  or  may  not,  be 
rendered  hydrous,  while  those  intersecting  impervious  metamorphic  rocks 
are  generally  anhydrous,  with  no  trace  of  vesiculation.     Owing  to  such  sub- 
terranean sources  of  moisture,  igneous  rocks  are  sometimes  hydrous  through- 
out, and   consequently   feeble   in   luster   and  wanting  in  durability.     In  a 
similar  way,  the  ascending  melted  rock  sometimes   gathers  in  bituminous 
materials  from  carbonaceous  shales,  and  puts  them  into  the  vesicles. 

Igneous  rocks  are  sometimes  divided  into  those  of  deep-seated  origin 
related  in  character  to  granite,  syenyte,  and  the  like  (called  plutonic  first  by 
Lyell),  and  other  igneous  rocks  and  lavas.  But  it  is  a  false  distinction;  for 
granite  is  no  more  of  deep-seated  origin  than  other  igneous  kinds. 

3.  The  ejections,  making  dikes  and  surficial  streams.  —  The  ejected  rock 
may  fill  a  fissure,  or  but  partly  fill  it.     On  the  other  hand,  it  may  flow  out  of 
a  fissure  in  a  stream  over  the  surface  of  the  country,  covering  the  exposed 
rocks  or  soil.     The  part  of  the  flow  within  the  fissure  is  a  dike,  whether 
there  is  an  outflow  or  not.     Fig.  219,  on  page  262,  represents  a  dike  with 
a  surficial  stream. 

(a)  Dikes.  —  Dikes  vary  in  width  from  an  inch  or  two  to  300  feet  or 
more,  and  in  position  from  vertical  to  horizontal,  and,  as  already  explained, 
are  usually,  unless  quite  small,  transversely  columnar.  The  smallest  are 
branches  from  a  larger  ;  for  an  inch-thick  stream  could  not  flow  far  between 
cold  rocks.  They  often  have  irregularities  and  interruptions  which  are  due 
to  a  faulting  of  the  rocks  intersected  subsequent  to  their  formation,  and 
others  owing  to  a  shifting  of  the  position  of  the  walls  of  the  fissure 
before  it  became  filled.  But,  further,  there  may  be,  before  the  filling,  a 
tumbling  in  of  one  wall,  or  the  other,  of  the  fissure,  especially  when  the 
fissure  is  much  inclined  and  the  intersected  rock  a  weak  one. 

On  the  following  map,  two  trap  dikes,  of  the  region  near  New  Haven, 
Conn.,  are  represented  (inclosed  by  dotted  lines),  which  are  divided  into 
short  parts,  owing  to  the  caving  in  of  the  overhanging  wall. 

The  Pine  Kock  dike  consists  of  four  such  parts  (A,B,CC,D),  and  Mill 
Rock  of  three  (AA,BB,  to  "Peak"  and  C).  The  inclination  of  the  dike  of 


HEAT. 


299 


Pine  Rock  is  35°  to  40°  from  a  vertical,  and  that  of  Mill  Rock,  22°.  East 
Rock  (in  which  the  surface  of  trap  is  widened  by  a  short  westward  outflow) 
owes  its  subdivision  into  short,  blunt  parts  (A,BB',CC'C",DD)  to  the  same 
cause ;  the  dike  has  a  dip  of  45°.  The  weak  sandstone  walls  of  these  dikes 
were  at  least  4000  feet  in  height,  and  a  downfall  of  the  unsupported  wall  was 
a  natural  result.  (D.,  1891.)  The  same  cause  opened  an  escape  fissure  to 
the  north  of  Mill  Rock,  at  D. 

267. 


268. 


269. 


Map  of  trap  dikes,  near  New  Haven,  Conn. ;  figures  give  heights  above  sea  level.    D. 

The  rock  of  the  outer  portion  of  a  dike,  besides  having  the  fineness  of 
texture  and  cracks  due  to  rapid  cooling,  may  be  soft  from  alteration,  or 
may  have  a  stratified  appearance  parallel  to  the  walls,  as  in  Figs.  268,  269 ; 
or  parallel  fissures  occupied  by  some  infiltrating  mineral ;  and  occasionally 
they  are  vesicular. 

(b)  Surficial  streams. — The  most  extensive  of  nearly  horizontal  igneous 
outflows  —  that  of  the  Deccan,  India  —  covers  an 
area  of  200,000  square  miles,  and  is  of  the  age  of  the 
Cretaceous  and  early  Tertiary  periods.  It  reaches 
from  the  seacoast  at  Bombay  to  the  railway  station 
at  Nagpur,  519  miles.  It  was  thickened  by  succes- 
sive flows  until  6000  feet  thick  near  Bombay,  2500 
feet  in  Cutch,  2000  to  2500  feet  at  its  southern 
limit ;  to  the  northwest  in  Sind  and  to  the  southeast, 
the  thickness  is  only  100  to  200  feet.  (Blanford.) 

Western  North  America,  while  remarkable  for  its 
great  volcanoes,  is  no  less  so  for  its  non-volcanic  rock-floods  ;  for  these  cover 
nearly  100,000  square  miles.     The  largest  continuous  region  stretches  from 


Dikes  with  the  columnar  struc- 
ture along  the  sides  imper- 
fect. D. 


300  DYNAMICAL   GEOLOGY. 

the  Yellowstone  Park  down  the  Snake  River  region.  It  spreads  north  over- 
Oregon  and  Washington.  There  are  many  other  areas  over  the  Great  Basin, 
to  the  south.  No  cones  exist  as  centers  of  these  floods  of  lavas,  but  to  the 
west  are  lofty  volcanoes  of  the  Cascade  Range.  In  the  Great  Basin  the 
lavas  of  the  areas  are  commonly  rhyolyte. 

The  two  following  figures  are  examples  of  surficial  outflows  and  of  parts 
of  Table  Mountain,  Cal.,  which  resulted  therefrom  through  denudation.  The 
melted  rock  flowed  over  the  gravels  and  river-beds  of  the  country,  and  thus 
obliterated  the  old  surface  features.  Subsequently  erosion  by  waters,  cutting 
through  the  igneous  layers,  and  then  through  the  easily  removable  beds 
beneath,  left  a  flat-topped  elevation.  Such  "  table  mountains,"  or  mesas,  are 

270.  271. 


Sections  of  Table  Mountain,  Tuolumne  County,  Cal. :  270,  at  Maine  Boys'  tunnel;  271,  at  Buckeye  tunnel, 

J.  D.  Whitney. 

common  in  California,  Arizona,  and  some  other  parts  of  the  Eocky  Mountain 
area.  These  fissures,  as  explained  by  Whitney,  show  the  old,  now  buried,  river 
valley  (cut  out  of  tilted  Sierra  schists,  d),  holding  in  the  river  bed  (at  a,  a) 
auriferous  gravel,  and,  above,  finer  fluvial  deposits  (c),  which  often  are 
partly  volcanic  ash,  and  sometimes  contain  silicified  stumps  and  logs ;  and, 
over  all,  the  cap  of  basalt  (6);  bv  is  part  of  the  outline  of  the  adjoining 
modern  valley.  Tunnels  (t)  are  made  through  the  "  rim-rock  "  of  such  old 
valleys  to  reach  the  gravel,  the  gold  being  collected  in  these  bottom  deposits 
because  of  its  weight. 

A  stream  of  melted  rock  usually  hardens  more  or  less  the  bed  of  sedi- 
mentary rock  over  which  it  flows;  or  it  bleaches,  blackens,  or  otherwise 
changes  it.  Should  it  change,  in  like  manner,  an  overlying  bed,  this  would 
be  evidence  that  the  stream  was  not  surficial  but  interstitial ;  that  is,  an 
intrusion  between  two  layers.  The  hardening  effects  often  fail,  however, 
because  there  was  no  moisture  present ;  for  dry  sands  cannot  be  hard  baked. 
Moreover,  coarse  pebbly  beds  are  consolidated  more  readily  than  shales, 
because  they  let  the  steam,  that  may  be  generated  from  moisture,  pass 
through  them,  when  the  fine  earthy  beds  do  not.  Hence  the  latter  may 
show  little  or  no  evidence  of  the  heat.  On  these  changes  see  further  under 
Metamorphism,  page  312. 

4.  Interstitial  out/lows.  —  The  intrusion  of  the  melted  rock  of  a  fissure 
between  the  layers  of  the  stratified  formation  it  intersects  may  be  either 
a  simple  gravitational  flow ;  or  a  forced  flow. 

(a)  The  melted  rock  will  naturally  flow  from  a  fissure  into  any  opened 


HEAT. 


301 


space  that  may  offer  a  way  of  escape ;  and  it  may  thus  put  layers  of  its  own 
material  into  the  stratified  series. 

(6)  The  lava  of  a  fissure  is  always  forced  along  by  pressure  from  below  ; 
and  if  the  fissure  fails  to  reach  the  surface,  the  ascending  stream  may  open 
a  space  for  itself  by  lifting  the  overlying  beds,  and  accumulate  in  great 
masses  in  the  chamber  so  made. 

An  intercalated  mass  of  igneous  rock  formed  in  the  latter  way  is  called, 
by  G.  K.  Gilbert,  a  laccolite,  from  the  Greek  for  lake,  because  it  is  a  lake-like 
expansion  of  a  stream.  (As  the  termination  ite  is  that  used  for  a  mineral  or 
rock,  the  form  laccolith,  like  that  of  monolith,  is  to  be  preferred.)  The 
thickness  depends  somewhat  on  the  fusibility  of  the  rock,  the  more  fusible 
kinds  making  extended  masses  or  sheets,  and  the  less  fusible  producing 
thicker  and  more  bulging  forms. 

The  Henry  Mountains  in  southern  Utah  are  of  laccolithic  origin,  and 
they  are  those  to  which  the  term  was 
first  applied  by  Gilbert.  The  following 
figures  are  from  his  memoir  (1877). 
The  greatest  thickness  of  the  strata 
bulged  upward  by  the  lifting  lava,  in 
the  manner  illustrated  in  Fig.  272,  was 
about  10,000  feet ;  and  the  height  of  the 
laccolithic  dome  in  some  cases  is  over 
3000  feet.  Fig.  273  represents  an  actual 
laccolith,  called  Jukes  Butte,  completely 
stripped  of  its  inclosing  strata  and  deeply  gorged  by  denudation.  The  rock 
is  andesyte,  a  rock  less  fusible  than  basalt ;  and  the  breadth  of  the  mass  is 
consequently  only  three  to  seven  times  greater  than  the  height. 

273. 


272. 


Ideal  section  of  a  laccolith.     Gilbert. 


Jukes  Butte,  a  denuded  laccolith,  as  seen  from  the  northwest.     Gilbert. 

From  the  laccolith  rise  dikes  of  andesyte.  .The  sandstone  adjoining  is 
usually  more  or  less  altered  by  the  heat  to  a  depth  of  a  foot  or  more.  The 
chamber  occupied  by  the  laccolith  was  in  all  cases  made  along  a  shaly  layer 
in  the  formation  where  the  cohesion  was  least.  They  occur  at  different 
levels  in  the  strata,  and  the  one  lowest  in  geological  position  is  4500  feet 
below  the  level  of  the  highest ;  the  former  is  between  Carboniferous  beds, 


302 


DYNAMICAL   GEOLOGY. 


and  the  latter  between  Cretaceous;   and  over  the  Cretaceous  lie  Tertiary 
beds. 

It  follows,  from  the  conditions  represented,  that  the  ascensive  thrust  of 
the  lava  was  so  powerful,  that  in  spite  of  friction  along  the  passage  and  the 
density  of  the  lava,  it  flowed  upward  for  an  unknown  number  of  miles  to  the 
laccolith  level ;  and  then  had  energy  enough  left  to  lift,  in  the  case  of  the 
laccolith  lowest  in  geological  level,  a  mass  of  beds  10,000  feet  or  more  thick 
and  2-25  in  average  specific  gravity  (equivalent  in  pressure  to  675  atmos- 
pheres) to  a  height  of  5000  feet.  Some  accession  to  the  force,  however,  may 
have  come  from  vapors  derived  from  subterranean  moisture,  or  from  waters 
encountered  on  the  way  up.  As  Mr.  Gilbert  states,  the  intrusion  of  the  lava 


274. 


276. 


275. 


277. 


274,  Ideal  outflow  of  the  main  East  Rock  dike;  275,  actual  outline  of  trap  in  the  same,  with  an  eastern 
supplementary  dike;  276,  same  in  a  second  East  Rock  summit,  called  Indian  Head;  277,  upturned  sandstone 
(with  talus  covering  part  of  it)  underneath  the  trap  of  West  Rock  along  a  transverse  section.  D.  '91. 

laterally  into  a  chamber  widened  the  area  of  pressure,  and  thus  enabled  it, 
on  the  principle  of  the  hydraulic  press,  to  accomplish  the  lift  by  very  slow 
steps  of  progress. 


HEAT.  303 

Among  the  trap-ridges  of  the  Connecticut  Valley,  East  Rock  (page  298) 
is  of  laccolithic  origin.  The  supply-fissure  for  East  Rock  dips  eastward  at 
about  45°.  The  liquid  rock  on  passing  up  the  fissure  between  the  sandstone 
walls,  whose  beds  also  dip  eastward,  but  at  an  angle  of  20°  to  25°,  forced  a 
passage  westward  between  the  beds  of  the  sandstone,  and  made  a  mass  of 
trap  200  to  250  feet  or  more  in  thickness,  and  about  300  yards  in  breadth. 
It  is  known  to  be  laccolithic  by  the  fact  that  the  sheet  of  trap  keeps  its 
thickness  quite  to  its  extreme  western  limit,  instead  of  thinning  by  gravity, 
like  a  surficial  flow,  and  that  it  has  also  a  rising  slope  throughout.  The 
section,  Fig.  274,  represents  the  intrusion  of  trap,  from  an  oblique  fissure, 
between  layers  of  sandstone,  in  laccolithic  style;  and  the  removal  of  the 
overlying  sandstone  would  give  it  a  general  resemblance  to  a  section  of  East 
Rock.  But  in  East  Rock,  and  also  in  West  Rock,  of  the  same  region  (see 
map,  page  299),  the  trap  of  the  outflow  rests  on  the  edge  of  upturned  layers 
of  sandstone,  and  it  has  less  dip  than  the  sandstone.  The  condition  in  East 
Rock  is  shown  in  Fig.  275,  and  that  in  a  second  summit  of  the  East  Rock 
Ridge,  in  Fig.  276.  Fig.  277  represents  part  of  a  long  exposure  of  the  up- 
turned sandstone  in  the  south  front  of  West  Rock  —  a  transverse  or  east- 
and-west  section  of  the  Rock.  Above  the  sandstone,  only  the  basal  portion 
of  the  columnar  trap  is  shown  in  the  figure,  and  below  it,  a  talus  of  fallen 
stones  and  earth.  The  forced  laccolithic  flow  of  the  liquid  rock  under  its 
heavy  cover  of  sandstone  must  have  caused  the  abrasion  of  the  fragile 
underlying  beds. 

In  some  cases  in  the  Connecticut  Valley,  portions  of  the  sandstone  and  trap,  at  the 
contact,  occur  rolled  into  rounded  forms,  and  make  part  of  an  intervening  layer  between 
the  trap  and  sandstone.  The  resistance  produced  by  the  weight  of  sandstone  above  fre- 
quently caused  the  opening  of  parallel  fissures,  for  the  escape  of  the  lavas ;  and  the  rock 
of  these  outflows  is  often  amygdaloidal,  when  the  rest  is  not,  owing  to  the  accumulation 
of  subterranean  waters  produced  in  consequence  of  the  damming  by  the  descending  dike. 

UNSOLVED  QUESTIONS  ABOUT  IGNEOUS  PHENOMENA. 

1.  Origin  of  the  ascensive  force.  —  The  ascensive  force  in  the  volcano 
has  been  attributed  to  (1)  the  expansive  action  of  moisture  from  the  deep- 
seated  source  of  the  lavas ;  and  (2)  the  gravitational  pressure  of  the  con- 
tracting crust  of  the  globe,  forcing  up  the  lavas ;  and  some  of  the  very  deep 
depressions  in  the  ocean's  bottom  near  volcanic  islands  are  thought  to  favor 
the  latter  theory.  In  view  of  the  fact  that  the  central  part  of  a  lava  column 
should  be  the  hotter,  it  is  queried  whether  there  is  not,  owing  to  the 
ascending  vapors,  a  more  rapid  rising  along  the  center,  and  a  consequent 
descending  along  the  sides  of  the  conduit. 

The  facts  afforded  by  Kilauea  indicate  that  the  upward  movement  in  a  lava  column, 
as  a  consequence  of  the  ascensive  force,  is  very  slow  —  360  feet  in  6  years  being  the 
maximum  observed  (page  280).  It  appears  also  to  follow  from  the  facts,  as  stated  on 
page  276,  that  the  force  in  the  conduit  varies  with  the  amount  of  moisture  received  from 
descending  subterranean  waters.  Daubree,  whose  experiments  on  the  perforating  power 


304  DYNAMICAL   GEOLOGY. 

of  vapor  on  rocks  when  suddenly  developed  along  an  opened  crack  (1890,  1891)  are  re- 
ferred to  on  page  278,  attributes  the  first  opening  of  the  conduit  tube  of  a  volcano  to  such 
action  of  vapors. 

2.  Source  of  igneous  fusion*— It  was  formerly  believed  that  the 
earth's  liquid  interior,  or  else  a  liquid  layer  beneath  the  crust,  or  isolated 
liquid  areas  in  place  of  a  liquid  layer,  supplied  the  liquid  rock  of  volcanoes. 
Now  it  is  generally  held  that  the  earth  is  solid  within,  but  that  below  a  thin 
exterior  there  is  a  temperature  just  below  that  of  fusion,  and  that  actual 
fusion  results  Avhenever  subterranean  pressures  cause  movements  and  thus 
develop  heat.  It  is  also  urged  that  the  removal  of  surface  pressure  might 
cause  fusion,  since  lessening  pressure  lowers  the  melting-point.  In  this 
process  fusion  takes  place  without  increase  of  heat ;  but  in  the  preceding, 
there  is  augmented  heat  of  dynamical  origin. 

Believing  in  the  earth's  igneous  fluidity,  Bunsen,  in  1851,  put  forth  the 
theory  that  within  the  .crust  the  earth  contains  an  acidic  layer  chiefly  of 
orthoclase  and  quartz  material  and  with  a  mean  percentage  of  silica  of  76*67 ; 
below  this  a  heavier  basic  layer  in  which  the  mean  percentage  of  silica  is 
but  47-48 ;  and  that  igneous  rocks  are  from  one  or  the  other  of  these  magmas, 
or  from  mixtures  of  the  two.  Bichthofen  in  his  "  Natural  System  of  Volcanic 
Bocks  "  (California  Acad.  Sci.,  1868),  after  a  study  of  the  rocks  of  the  Pacific 
border  of  the  United  States,  announced  as  the  order  of  eruption  in  igneous 
regions  :  propylyte  (since  shown  to  be  andesyte),  andesyte,  trachyte,  rhyolyte 
(quartz-trachyte),  basalt  —  basalt  being  the  latest  —  when  present  with  the 
others. 

More  recently,  Iddings  has  concluded  that  the  different  kinds  have  arisen 
from  local  differentiation  of  a  common  magma;  that  the  first  that  appears  in  a 
region  is  usually  one  having  the  mean  composition  of  the  series  in  that  region, 
and  that  the  last  is  a  rock  of  one  or  both  extremes,  that  is  either  rhyolyte 
(quartz-trachyte),  or  basalt,  or  both;  also  that  in  each  case  the  portions  of 
the  magma  that  are  latest  to  be  extruded  are  the  solvent  for  the  other  portions. 

A.  D.  Hague  has  found,  in  the  Leadville  region,  the  succession  in  the 
ejected  rocks  to  be  (1)  andesyte,  (2)  dacyte,  (3)  rhyolyte,  (4)  basalt ;  and  he 
regards  it  as  the  prevailing  order. 

This  order — which  is  near  that  of  Bichthofen  — corresponds  to  a  succes- 
sion from  (1)  soda-lime  semibasic  lavas,  to  (2)  potash-bearing  or  acidic  lavas  ; 
to  (3)  basic  lavas:  also  from  (1)  those  of  medium  fusibility;  to  (2)  those 
of  difficult  fusibility;  to  (3)  those  of  easy  fusibility  or  which  melt  at 
the  lowest  temperature :  also  from  (1)  those  of  medium  specific  gravity ; 
to  (2)  those  of  least  specific  gravity  ;  to  (3)  those  of  greatest  specific  gravity. 
No  further  physical  or  chemical  explanation  for  the  succession  is  yet  given. 
If  fusibility  is  the  important  principle  in  determining  distributions,  then 
basalt  should  generally  be,  as  the  facts  make  it,  the  last  and  the  uppermost. 
Mount  Loa  shows  that  specific  gravity  has  little  or  no  importance ;  for  the 
heaviest  chrysolitic  basalts  occur  not  only  below,  but  also  at  the  summit, 
although  it  is  nearly  14,000  feet  above  the  sea  level. 


HEAT.  305 

THERMAL  WATERS,  GEYSERS. 

The  subject  of  thermal  waters  constitutes  an  important  part  of  Chemical 
Geology,  and  is  here  only  briefly  treated.  Hot  springs  are  (1)  common  in 
volcanic  regions,  and  (2)  occur  also  along  the  courses  of  non-volcanic  erup- 
tions. They  are  occasionally  met  with,  away  from  all  igneous  eruptions,  (3) 
on  the  lines  of  faults  or  the  axes  of  flexures,  and  sometimes  (4)  where  there 
are  none  of  these  conditions.  The  heat  in  the  first  two  cases  is  generally 
of  volcanic,  or  deep  subterranean,  origin ;  but  in  the  others  it  may  come 
from  the  oxidation  of  sulphides,  or  from  other  chemical  action. 

When  the  temperature  is  high,  the  waters  may  be  either  approximately 
pure,  or  strong  mineral  solutions.     The  waters  often  hold  silica  in  solution, 
whose  deposition,  over  the  region  around,  makes 
irregular  accumulations  of  a  coarse  opal,  or  rarely  278- 

of  quartz,  and  forms  low  cones  or  rims  about 
basins.  Occasionally,  the  waters  are  calcareous, 
instead  of  siliceous,  and  make  calcareous  basins 
or  cones.  The  sources  of  such  solutions,  and 
some  of  the  effects  resulting  from  them,  are  ex- 
explained  on  pages  131,  135,  and  beyond. 

Geysers.  —  When  a  spring  or  basin  of  hot 
water  is  in  nearly  constant  ebullition,  or  is  alter- 
nately  boiling  and  quiet,  it  is  simply  a  hot  spring 

or  basin.  But  if  the  water  is  thrown  up  at  nearly  regular  intervals,  in  jets, 
it  is  called  a  geyser.  Iceland  has  long  been  noted  for  its  geysers,  and  the 
theory  of  geyser  action  was  there  first  investigated  by  Bunsen  and  Des 
Cloizeaux.  It  has  one  great  geyser  in  the  vicinity  of  Hecla,  among  many 
hot  springs.  The  geyser  sends  up  a  great  jet  of  100  feet  once  in  about  30 
hours,  and  other  smaller  ones  in  the  interval.  The  Icelandic  word  means  a 
"  gusher."  New  Zealand  has  its  geyser  region,  about  Lake  Eotomahana,  in 
the  northern  island,  and  had  beautiful  geyserite  terraces  until  the  volcanic 
eruption  of  Tarawera  in  1886,  when  mud  eruptions  buried  them. 

Far  exceeding  either  of  these  regions  is  the  geyser  area  of  Yellowstone 
Park,  first  described  by  Messrs.  Cook  and  Folsom  in  1870,  and  by  the  Hayden 
expedition  in  its  volumes  for  1871,  1872.  and  1878,  the  last  containing  an 
extended  account  by  A.  C.  Peale.  The  region  has  since  been  further 
studied  and  described  by  A.  Hague,  J.  P.  Iddings,  W.  H.  Weed,  and  others. 
The  geysers  are  situated  mainly  about  the  Fire-Hole  Fork  of  the  Madison, 
and  near  Shoshone  Lake  at  the  head  of  Lake  Fork  of  the  Snake.  They 
are  exceedingly  numerous,  and  play  at  all  heights  up  to  200  feet  or  more ; 
and,  besides,  there  are  multitudes  of  hot  springs  of  various  temperatures, 
the  most  of  them  between  160°  and  200°  F.,  the  boiling-point  of  the  region 
being  198°  to  199°  F.  There  are  also  "  mud-volcanoes  "  where  steam  issues 
through  thick  mud  or  muddy  waters,  producing,  at  times,  ebullition,  and 
occasionally  geyser  action.  The  principal  locality  at  the  park  is  four  miles 
DANA'S  MANUAL  —  20 


306 


DYNAMICAL    GEOLOGY. 


north  of  Yellowstone  Lake,  and  six  from  "  Crater  Hills."  Some  of  the  mud 
pools  are  simply  muddy  water ;  others  are  like  kettles  of  boiling  soap ;  some 
like  caldrons  of  mush  or  paint,  and  still  others  like  stiff  mortar.  They  vary 
in  stiffness  with  the  dryness  of  the  season.  They  have  generally  a  circular 
pit  10  feet  deep,  and  rise  sometimes  into  a  mound  several  feet  above  the 
general  level.  All  together,  the  number  of  hot  springs  and  geysers  in  this 
region  cannot  be  less  than  10,000.  The  hot  waters  are  usually  siliceous, 

279. 


and  deposit  the  silica  in  the  form  of  a  tufaceous  or  porous  opal  called  gey- 
serite.  It  makes  cones  and  basins  of  various  shapes,  and  covers  the  surface 
over  wide  areas.  The  deposits  of  the  Gardiners  Eiver  at  the  Mammoth  Hot 
Springs  are  calcareous ;  Fig.  282  represents  one  of  its  calcareous  cones,  the 


HEAT.  SOT 

"  Liberty  Cap,"  50  feet  high  and  20  feet  in  diameter ;  and  Fig.  136,  on  page 
132,  represents  calcareous  (travertine)  terraces  on  this  river. 

One  of  the  geysers  in  the  Upper  Geyser  Basin  of  the  Fire-Hole  is  shown 
in  action  in  Fig.  283 ;  the  cone  (Fig.  281)  is  but  3  ft.  high  and  5  in  diameter, 
but  it  throws  up  a  jet  beyond  200  ft.  in  height  about  once  a  day. 

In  the  eruption  of  a  geyser,  the  jet  is  first  water,  then  much  steam  with 
the  water,  and,  at  last,  mostly  or  wholly  steam,  the  water  having  been  all 
thrown  out ;  and,  when  the  water  partly  falls  or  runs  back  into  the  basin, 
the  eruption  is  sometimes  renewed  successively,  before  finally  stopping. 

280.  281.  282. 


Giant  Geyser.  Beehive.  Liberty  Cap. 

The  intermittent  action  is  owing  (1)  to  the  access  of  subterranean  waters 
to  hot  rocks,  producing  steam,  which  seeks  exit  by  conduits  upward ;  (2)  to 
cooler  superficial  waters  descending  those  conduits  to  where  the  steam  pre- 
vents farther  descent,  and  gradually  accumulating  until  the  conduit  is  filled 
to  the  top ;  (3)  to  the  heating  up  of  these  upper  waters  by  the  steam  from 
below  to  near  the  boiling-point ;  when  (4)  the  lower  portion  of  these  upper 
waters  becomes  converted  into  steam,  and  the  jet  of  water,  or  eruption, 
ensues.  This  is  nearly  the  explanation  given  by  Bunsen  after  an  examina- 
tion of  the  geysers  of  Iceland.  The  deposit  of  silica  in  the  throat  of  the 
conduit,  after  an  eruption,  tends  to  diminish  its  size,  and  sometimes  closes  it 
completely,  so  that  the  waters  are  obliged  to  open  a  new  vent. 

The  beauty  of  the  siliceous  geyser-cones  is  often  enhanced  by  the  delicate  tints  of 
pink,  buff,  yellow,  etc.,  mingled  with  white,  over  their  surfaces.  Pebbles  in  the  bottom 
of  the  small  basins  formed  about  the  cones  are  commonly  concretions  of  geyserite,  like 
the  rosettes  of  the  bottom  and  sides.  Fig.  280  represents  the  cone  of  the  "  Giant "  geyser, 
in  the  Upper  Geyser  Basin  of  the  Fire-Hole  ;  it  is  about  10  feet  high  and  24  feet  in  di- 
ameter at  base,  and  has  one  side  partly  broken  down  and  bent  inward.  It  throws  out, 
at  long  intervals,  a  jet  90  to  200  feet  in  height.  "Old  Faithful "  is  one  of  the  largest  of 
the  Madison  River  geysers  ;  it  has  a  low  and  broad  irregular  cone,  and  throws  up  its  great 
jet  to  a  height  of  150  feet,  once  in  about  65  minutes,  the  remarkable  regularity  of  its 
action  having  suggested  the  name  it  bears.  The  "  Giantess,"  another  of  the  large  geysers 
of  the  Fire-Hole,  throws  a  still  larger  body  of  water  to  the  same  height.  Another,  the 
"Architectural"  geyser,  is  actually,  when  in  action,  a  combination  of  jets  of  various 
sizes  and  angles  of  inclination,  each  having  some  independence  in  its  movements,  but  all 
working  together,  and  producing  a  marvelous  effect  from  the  ever-changing  views. 

Frank  H.  Bradley  observes  that,  while  standing  on  the  mound  of  "  Fountain  "  geyser, 
whose  pool  was  overflowing,  and  watching  a  steam-jet  a  hundred  yards  away,  the  jets  sud- 
denly ceased,  and  "  Fountain  "  commenced  throwing  up  a  jet,  10  feet  in  diameter,  to  vary- 


308 


DYNAMICAL   GEOLOGY. 


ing  heights,  from  5  to  40  feet.  In  30  minutes,  "  Fountain  "  stopped  suddenly,  and  imme- 
diately the  steam-jet  began  again  ;  in  20  minutes  more,  the  jet  again  stopped,  and  at 
once  a  small  pool  a  few  yards  from  "Fountain,"  which  was  empty  when  that  was  play- 
ing, but  had  become  partly  filled  from  its  overflow,  began  to  boil  and  throw  up  water  to  a 
height  of  5  or  10  feet,  and  continued  this  for  half  an  hour ;  as  it  moderated,  the  steam-jet 
opened  anew,  but  ceased  when  the  boiling  became  more  violent.  The  facts,  illustrated 
in  other  parts  of  the  region,  prove  a  sympathy  between  different  vents. 

283. 


Beehive  Geyser  in  action.    Holmes. 

On  page  152,  the  agency  of  plants  (Algae)  in  the  deposition  of  the  silica  and  calcare- 
ous material  of  the  geysers  (first  observed  by  W.  H.  Weed)  is  described. 

There  is  a  small  geyser  region  on  Sa5  Miguel,  one  of  the  Azores,  in  the  north  Atlantic. 
It  is  situated  in  the  Val  de  Furnas,  where  three  centuries  since  there  was  a  volcanic 


HEAT  —  METAMORPHISM.  309 

eruption.  The  hot  waters  are  in  constant  ebullition  and  have  their  intermittent  jets.  Be- 
sides escaping  steam,  there  is  some  carbonic  acid  given  out,  and  siliceous  deposits  are 
made  from  the  hot  waters.  Geysers  occur  also  on  the  island  of  Celebes,  in  the  volcanic 
region  on  its  northeastern  extremity  in  the  district  of  Manado. 

IV.    METAMORPHISM. 

Metamorphism  signifies  change :  not  merely  change  in  form,  as  might 
be  inferred  from  the  composition  of  the  word,  but  also,  like  the  correspond- 
ing word  metamorphosis,  change  in  nature  or  constitution.  In  geology,  it  is 
change  in  texture,  crystalline  structure,  or  mineral  constitution ;  as  when  a 
common  limestone  becomes  crystallized,  and  thereby  converted  into  statuary 
marble,  or  a  sandstone  into  gneiss  or  granite,  or  an  augitic  rock  into  a  horn- 
blende rock,  or  a  massive  rock  into  a  laminated  or  foliated  kind. 

The  terms  metamorpliic  and  metamorphism  were  proposed  by  Lyell  in 
the  first  edition  of  his  Principles  of  Geology  (1831-1833)  with  reference  to 
altered  rocks  of  both  local  and  regional  extent. 

In  Vol.  III.  he  says,  on  page  372 :  "  It  appears  from  sections  described 
by  Hugi,  that  some  of  the  secondary  beds  of  limestone  and  slate,  which  are 
overlaid  by  granite,  have  been  altered  into  gneiss  and  mica  schist.  These 
altered  sedimentary  formations  are  supposed  by  M.  Elie  de  Beaumont  to  be 
of  the  age  of  the  Lias  of  England,  and  others  to  be  even  as  modern  as  the 
Jurassic  or  Oolytic  formations."  On  page  373  he  says :  "  According  to 
these  views,  gneiss  and  mica  schist  may  be  nothing  more  than  micaceous  and 
argillaceous  sandstones  altered  by  heat,  and  certainly  in  their  mode  of  strati- 
fication and  lamination,  they  correspond  most  exactly." 

"  Granular  quartz  may  have  been  derived  from  siliceous  sandstone ;  clay 
slate  may  be  altered  shale,  and  shale  appears  to  be  clay  which  has  been 
subjected  to  great  pressure."  "  Granular  marble  has  originated  in  the  form 
of  ordinary  marble,  having  in  many  instances  been  replete  with  shells  and 
corals  now  obliterated."  In  the  edition  of  1842,  he  speaks  of  fossiliferous 
formations,  some  of  them  of  the  age  of  the  Silurian  strata,  as  near  Christiania 
in  Norway,  others  belonging  to  the  Oolytic  period,  as  around  Carrara  in 
Italy,  which  had  been  converted  partially  into  gneiss  and  mica  schist  and 
statuary  marble.  Among  local  changes  he  mentions  the  case  of  the  basalt 
dike  in  Anglesea,  134  feet  wide,  cutting  through  strata  of  shale  and  limestone 
which  were  altered  for  30  feet  from  the  dike,  "  having  the  shale  in  several 
places  converted  into  hard  porcelanous  jasper,  in  the  hardest  parts  of  which 
the  fossil  shells,  principally  Productce,  were  nearly  obliterated  " ;  "  and  the 
argillaceous  limestone  had  lost  its  earthy  texture  and  become  granular 
and  crystalline.'7  Through  investigation  since,  such  facts,  both  of  regional 
and  local  origin,  have  been  greatly  multiplied. 

The  Taconic  region,  on  the  borders  of  New  York  and  New  England, 
affords  a  good  illustration.  The  rocks  are  least  crystalline  in  the  northern 
and  the  western  parts  of  the  region,  and  consequently  fossils  were  to  be 
looked  for  in  those  parts.  They  have  been  found  in  Vermont  down  to 


310  DYNAMICAL   GEOLOGY. 

\ 

and  beyond  the  Massachusetts  line  —  Cambrian  fossils  in  the  sandstone  or 
quartzyte,  and  Cambrian  and  Silurian  in  the  crystalline  limestone  or  marble 
belt  next  west ;  and  a  few  miles  farther  west  they  occur  going  southward  in 
limestones  and  schists  for  150  miles  to  Poughkeepsie  in  Dutchess  Co.,  N.  Y., 
and  beyond.  In  the  more  crystalline  parts  of  the  same  region  to  the  east- 
ward in  Massachusetts,  the  quartzyte  graduates  into  gneiss  and  alternates 
with  mica  schists,  and  the  slates  change  to  staurolitic  mica  schists  and 
gneiss.  The  fossils  in  the  Taconic  region  were  found  by  A.  Wing,  Walcott, 
Dwight,  Dale,  Wolff,  and  others. 

Again,  near  Bernardston,  Mass.,  and  the  region  northward  along  the  Connecticut 
Valley,  Crinoids  and  Brachiopods  occur  in  a  crystalline  limestone  of  Devonian  age,  asso- 
ciated with  hydromica  schist,  gneiss,  granite,  dioryte,  hornblende  schist,  quartzyte,  all  of 
one  Devonian  series,  and  of  synchronous  metamorphism.  (E.  Hitchcock,  B.  K.  Emerson.) 

In  the  Alps,  at  the  St.  Gothard  tunnel,  crinoidal  remains  occur  in  calcareous  mica 
schist  (Mtiller).  In  the  Apuan  Alps,  Orthocerata  exist  in  limestone  between  beds  of 
gneiss  and  mica  schist  (Meneghini).  At  Brevig,  Norway,  a  Silurian  limestone  contains 
garnets,  scapolite,  and  fossils,  and,  according  to  Reusch,  mica  schist  containing  Halysites, 
Favosites,  Cyathophyllum,  Murchisonia,  Calymene,  Dalmanites.  Schists,  in  Brittany, 
afford  andalusite  crystals  and  species  of  Orthis,  Spirifer,  and  Calymene,  in  one  and  the 
same  specimen  (Boblaye).  At  Rothau,  in  the  Vosges,  in  a  hornblende  rock,  corals  occur 
replaced,  as  stated  by  Daubree,  without  losing  their  form,  by  crystals  of  hornblende, 
garnet,  and  axinite,  and  among  the  corals  the  species  Calamopora  spongites  is  quite 
distinct. 

The  rocks  that  have  become  changed  into  metamorphic  rocks  are  for  the 
most  part  the  fragmental  rocks,  as  sandstones,  shales,  conglomerates,  with 
the  limestones.  These,  according  to  their  various  constitution,  have  been 
changed  to  gneiss,  granite,  mica  schist,  and  the  several  other  kinds  of  schist ; 
and  the  limestones  to  crystalline  limestones ;  and  this  change  has  been  the 
chief  method  of  origin  of  the  schists.  In  addition,  the  many  crystalline 
rocks,  both  the  metamorphic  and  igneous,  have  undergone,  to  some  extent, 
related  changes. 

Under  metamorphism  might  be  included  the  chemical  changes  in  rocks 
and  minerals  that  take  place  at  the  ordinary  temperature.  But  these  run 
down  into  the  common  results  of  decay,  and  are  more  conveniently  kept 
separate.  They  have  been  described  on  page  118  and  beyond. 

CAUSES  OF  METAMORPHISM. 

1.  Not  generally  due  to  infiltrating  waters.  —  The  metamorphic  changes 
which  rocks  have  undergone  is  no  evidence  of  their  instability  under  existing 
conditions.  It  has  been  already  shown  that  the  sandstone,  shales,  and 
other  fragmental  rocks  are  seldom  so  porous  at  depths  below  as  to  admit  the 
passage  of  infiltrating  waters.  It  is  true  also  of  the  crystalline  rocks, 
granite,  gneiss,  syenyte,  and  the  various  igneous  rocks,  that  they  are  com- 
monly too  close  in  texture  to  admit  the  passage  of  underground  waters.  The 
moisture  they  hold  is  stable,  and  the  rocks  are  stable  against  changes  from 


HEAT METAMORPHISM.  311 

such  a  source.  In  outcrops  of  an  Archaean  granite,  the  feldspar  and  mica  are 
usually  as  perfect  as  when  made  in  Archaean  time,  excepting  a  thin  layer  of 
surface  alteration.  So  in  many  of  the  outcrops  of  trap,  the  pyroxene 
and  labradorite  are  still  unchanged  pyroxene  and  labradorite;  and  this, 
though  millions  of  years  have  intervened  since  the  outflow ;  and  millions 
of  years  of  uniformity  are  sufficient  to  prove  stability.  The  thin  layer 
of  surface  alteration  indicates  the  depth  of  permeation,  and  to  this  depth 
there  is  alteration,  but  not  metamorphism.  Buried  in  subterranean  waters, 
the  conditions  would  be  the  same  except  that  even  surface  alteration  would 
be  prevented;  for  a  sandstone  that  will  fall  to  pieces  when  exposed  to 
the  air  will  make  durable  underwater  abutments.  A  trap  ledge  that 
decays  to  a  depth  of  two  or  three  feet,  when  it  is  above  the  tide-level,  will 
remain  solid  and  wholly  unaltered  below  low  tide.  Pyrite  and  other 
iron-bearing  minerals  oxidize,  and  help  on  the  decay  in  the  outer  layer  where 
it  is  exposed  to  the  air;  but  below  this  they  remain  unchanged.  White 
marble,  although  a  more  porous  rock  than  most  others,  usually  retains  its 
whiteness  perfect  through  the  body  of  the  rock,  its  pyrite  and  other  imbedded 
minerals  losing  nothing  in  their  luster  or  composition. 

2.  Heat  above  the  ordinary  temperature  usually  necessary.  —  Lyell  attrib- 
uted metamorphism  to  the  heat  of  the  earth's  interior.     The  rocks  bore 
evidence,  in  the  position  of  the  beds,  of  upturnings  and  of  great  pressure ; 
and  those  which  were  left  deepest  as  a  consequence  of  the  movements  became 
crystalline  or  metamorphic.     They  were  hence  also  called  by  him  Hypogene 
rocks.     Effects  from  dynamical  forces  were  here  recognized,  but  the  heat 
was  statical  heat. 

This  continued  to  be  the  theory  of  geologists  until  1868,  when  Henry 
Wurtz,  of  New  Jersey,  in  the  American  Journal  of  Mining,  announced  the 
principle  that  metamorphism  was  due  to  heat  derived  from  the  friction  at- 
tending the  upturning  of  the  rocks,  that  is,  to  heat  of  dynamical  origin. 
In  the  editions  of  this  work  since  that  date  this  theory  of  regional 
metamorphisnij  through  heat  of  a  dynamical  source,  has  been  adopted.  But 
it  has  also  been  recognized  that  heat  of  a  dynamical  source  has  been  more  or 
less  supplemented  by  heat  from  the  earth's  interior,  that  is,  by  statical  heat. 
At  the  same  time  statical  heat  has  been  referred  to  as  also  the  source  of  local 
metamorphism.  It  should  be  observed  here  that  it  is  the  heat  that  is 
dynamic,  not  the  metamorphism ;  for  the  metamorphism  is  the  same  whatever 
the  source  of  the  heat,  whether  dynamical  or  statical,  except  in  some  minor 
points  due  to  pressure,  as  explained  beyond. 

3.  The  presence  of  moisture.  —  All  rocks  are  permeated  by  moisture,  and 
this   permeating   moisture  is  sufficient  for  all  metamorphic  results.     The 
amount  ordinarily  present  is  stated  on  page  205.     If  2-67  per  cent,  which  is 
less  than  the  average,  the  amount  would  correspond  to  two  quarts  of  water 
for  each  cubic  foot  of  rock.     At  one  per  cent  it  would  be  one  pound,  and, 
therefore,  one  pint  of  water  to  100  pounds  or  two  thirds  of  a  cubic  foot  of 
rock ;  and,  since  a  pint  contains  29  cubic  inches  of  water,  this  amount  would 


312  DYNAMICAL   GEOLOGY. 

afford,  at  the  ordinary  pressure,  nearly  45  cubic  feet  of  steam  to  the  cubic 
foot  of  rock.  There  is  no  doubt,  therefore,  about  enough  moisture. 

The  distribution  of  heat  through  the  rocks  without  the  aid  of  moisture 
is  impossible ;  for  heat  travels  but  a  short  way  into  dry  rock.  A  thickness 
of  two  or  three  feet  is  sufficient  to  confine  nearly  all  the  heat  of  the  hottest 
furnace,  and  will  make  it  safe  to  walk  over  liquid  lavas.  But  let  the  walls 
of  the  furnace  be  wet,  and  the  heat  will  go  through  with  a  rush,  for  the 
water  becomes  steam. 

4.  Pressure.  —  Pressure,  as  already  stated,  is  the  chief  source  of  the 
movements  by  which  a  large  part  of  the  heat  for  metamorphism  was  pro- 
duced. It  has  caused  (1)  a  foliated  structure  in  slates  and  other  rocks,  and 
(2)  minor  changes  in  the  texture  of  rocks.  The  first  of  these  subjects  is 
treated  under  mountain-making ;  the  second,  on  page  321. 

In  the  following  remarks,  local  metamorphism  is  first  considered,  and 
then  regional. 

LOCAL  METAMORPHISM. 

Local  metamorphism,  as  above  explained,  makes  changes  in  rocks  in  the 
vicinity  of  the  source  of  heat,  as  those  of  the  walls  of  dikes.  The  results 
are  often  called  contact-phenomena,  and  any  minerals  formed,  contact-minerals. 

The  results  of  change  along  the  walls  of  trap  dikes  in  the  Triassic  areas 
of  eastern  North  America  comprise  minerals  in  the  inclosing  rock,  in  the 
dike,  or  partly  in  both.  They  include  crystallizations  of  epidote,  tourmaline, 
garnet,  chlorite,  quartz,  hematite,  and  magnetite,  besides  various  zeolites. 
Garnets  occur  in  the  sandstone  within  a  few  yards  of  the  trap,  and  also  in 
rifts  in  the  trap  near  its  walls,  and  sometimes  the  latter  are  yellow  topazo- 
lites  of  great  beauty.  Many  square  yards  of  the  surface  of  a  joint  in  the 
trap  of  East  Rock,  at  New  Haven,  Conn.,  are  thickly  covered  with  garnets  and 
crystals  of  magnetite.  At  Eocky  Hill,  N.  J.,  according  to  H.  D.  Eogers 
(1840),  the  "baking"  effects  of  a  trap  dike  are  distinct  for  a  fourth  of  a  mile 
from  the  dike ;  and,  fifty  feet  off,  a  thin  bed  contains  "  kernels  of  pure  epi- 
dote," and  cavities  that  are  "studded  with  crystals  of  tourmaline;"  arid  at 
one  place  the  latter  crystals  are  half  an  inch  in  diameter.  The  sandstone, 
when  containing  these  minerals,  has  generally  lost  its  usual  red  color  and 
become  grayish-white  to  greenish,  the  green  color  coming  sometimes  from 
the  chlorite  or  epidote  generated  by  the  heat. 

The  production  of  the  metamorphic  results,  and  the  extent  of  the  region 
affected,  has  depended  chiefly  on  the  presence  of  moisture  for  conveying  and 
utilizing  the  heat.  The  sandstone  walls  of  a  dike  may  crumble  into  small 
chips,  because  of  the  want  of  moisture  there  at  the  time  of  the  eruption, 
while  in  other  places  the  rock  becomes  firmly  consolidated.  The  presence 
of  steam  is  sometimes  indicated  by  remains  of  the  tubular  channels  through 
which  it  rushed,  their  walls  being  bleached  and  penetrated  with  chlorite ; 
and  chlorite  may  occur,  in  some  places  near  by,  spangled  with  minute  but 
perfect  crystals  of  hematite. 


HEAT  —  METAMORPHISM.  313 

A  trap  dike  intersecting  the  clayey  layers,  sandstones,  and  coal-beds  of 
the  island  of  Nobby,  near  Newcastle,  New  South  Wales,  has  baked  the  clayey 
layers  to  a  flint-like  rock  to  a  distance  of  200  yards  from  the  dike,  the  whole 
length  of  the  island.  (D.,  1849.) 

In  the  Spanish  Peaks  region,  southeastern  Colorado,  the  injection  of  ig- 
neous rocks  across  coal-beds  has  produced,  according  to  R.  C.  Hills,  a  dense 
natural  coke  or  an  impure  powdery  graphite.  The  outcrop  of  coke  thus 
made  near  Trinidad  is  probably  two  miles  long;  and  at  other  places  similar 
outcrops  are  four  to  five  miles  in  length. 

A  region  of  igneous  eruptions  is  often  also,  as  a  consequent  or  concurrent 
fact,  a  region  of  steaming  fissures  and  of  hot  springs,  conveying  the  heated 
moisture  widely  through  the  strata  of  the  region ;  and  in  this  way  probably 
the  sand-beds  of  the  Mesozoic  formations  of  eastern  America  were  generally 
reddened  as  well  as  consolidated. 

Baking  effects,  and  sometimes  crystallizations,  have  been  occasioned  by 
the  burning  of  coal-beds.  (See  page  266.) 

In  the  Tyrol,  near  Monzoni  and  Predazzo,  a  Peruvian  limestone,  in  the  vicinity  of 
masses  of  igneous  rocks,  has  been  crystallized,  and  near  the  contacts  occur  garnet,  ido- 
crase,  gehlenite,  epidote,  spinel,  mica,  anorthite,  magnetite,  hematite,  and  apatite.  (Dcel- 
ter,  1875.)  In  the  White  Mountains,  near  Crawford's,  alongside  of  granite,  an  argillitic 
mica  schist  is  much  altered  and  penetrated  with  crystals  of  orthoclase  and  tourmaline. 
(Hawes,  1881.) 

These  examples  of  alteration  illustrate  not  only  local  but  also  regional 
metamorphism,  for  the  minerals  formed  are  among  those  that  figure  exten- 
sively in  metamorphic  rocks.  Chlorite,  garnet,  tourmaline,  are  among  the 
most  common  of  such  minerals  ;  and  if  these  and  other  species  can  be  made 
under  the  rather  rapid  and  coarse  conditions  afforded  by  the  eruption  of  an 
igneous  rock,  the  results  of  slow-working  metamorphism  should  be  much  more 
complete. 

It  is  observed,  also,  that  these  minerals  are  made  by  selecting  and 
combining  the  needed  elements.  The  iron  of  the  epidote,  chlorite,  garnet, 
tourmaline,  must  be  the  iron  that  gives  the  red  color  almost  everywhere  else 
to  the  enclosing  rock,  or  is  present  in  occasional  grains  of  magnetite.  The 
tourmaline  crystals  seem  to  show  that  marine  waters  (or,  perhaps,  borate 
springs,  made  earlier  from  the  ocean's  waters)  may  supply  boracic  acid  which 
they  require.  The  hematite  crystals  (Fe203)  may  be  derived  from  dissemi- 
nated red  hematite  coloring  the  rock,  or  from  the  oxidation  of  grains  of 
magnetite  (Fe304) .  The  quartz  crystals  were  made  out  of  silica  taken  from 
the  siliceous  minerals  (feldspar,  etc.)  that  were  decomposed  by  the  steam  to 
furnish  material  for  the  new  crystallizations ;  and  the  heat,  as  far  as  it 
reached  through  the  sand-beds,  even  if  of  low  degree,  in  the  same  way  made 
the  siliceous  solutions  that  produced  the  consolidation  of  the  rocks  adjoining. 

Special  metamorphic  power  is  often  attributed  to  granite  in  the  dike-like  condition, 
and  the  minerals  in  the  rock  adjoining  are  regarded  as  contact  minerals  when  the  granite 


314  DYNAMICAL   GEOLOGY. 

is  actually  a  vein-formation.  Granite  eruptions  have  no  more  metamorphic  power  over 
the  adjoining  rocks  than  those  of  trachyte ;  for  granite  in  the  melted  state  is  identi- 
cal, essentially,  with  melted  quartz  trachyte,  and  conforms  to  the  same  principles  as 
regards  cooling.  The  walls  of  the  dike,  or  mass,  will  rapidly  chill  against  the  cold  inclos- 
ing rock,  and  fail  of  the  coarse  crystalline  texture  of  granite  ;  and  the  dike,  or  mass,  will 
take  the  coarse  texture  only  under  conditions  as  to  thickness  of  mass  that  admit  of 
extreme  slowness  of  cooling.  The  crystallizing  of  adjoining  rocks  to  any  great  distance 
by  ejected  granite  is  as  improbable  as  the  same  by  ejected  trachyte.  The  alleged  exam- 
ples of  such  change  in  which  the  walls  retain  their  coarse  crystallization  but  little  altered 
(when  at  all),  and  where  the  metamorphic  schists  adjoining  are  supposed  to  afford  an 
example  of  what  ejected  granite  can  do,  are,  probably,  either  examples  of  cotemporaneous 
metamorphism,  and  the  contact  minerals  some  of  the  products  made  by  the  process  in  the 
transition  region  between  the  terranes  or  strata  ;  or  of  metamorphism  in  overlying 
beds  that  were  upturned  and  thrust  against  the  preexisting  range  of  granite,  and  which 
became  altered  or  crystalline  as  a  consequence  of  the  friction. 

REGIONAL  METAMORPHISM. 

Regional  metamorphism  is  here  considered  under  the  following  heads  :  — 
(1)  INCIPIENT  METAMORPHISM,  that  of   the  lower  or  incipient   stages; 

(2)  CRYSTALLINIC,  or  that  in  which  there  is  simply  change  in  crystallization ; 

(3)  PARAMORPHIC,  or  that  of  a  change  in  crystalline  form  and  not  in  com- 
position, as  when  pyroxene  is  changed  to  hornblende,  or  aragonite  to  calcite ; 

(4)  METACHEMIC,  in  which  there  is  change  in  chemical  constitution  (also 
styled  metasomatic,  which  means  change  in  the  body  of  the  rock,  a  general 
fact  under  metamorphism)  ;   (5)  ENDO-CRYSTALLIC,  or  effects  of  pressure  in 
modifying  the  structure  of  crystals,  or  in  fracturing  them.     Finally,  after 
considering  the  metamorphic  effects  produced  in  uncrystalline  rocks,  those 
occurring  in  crystalline  rocks  are  described. 

The  general  effects  of  metamorphism  are  the  following:  — 

In  the  lower  or  incipient  stage  it  discolors,  dries,  consolidates.  In 
higher  stages  it  crystallizes  the  constituents  of  rocks ;  it  often  produces  also 
chemical  changes,  making  new  minerals  in  the  mass ;  and,  as  a  result,  oblit- 
erates fossils.  Under  the  high  temperature,  which  may  attend  it,  all  the 
methods  of  mineral  chemistry  in  nature  have  a  chance  for  work  according  to 
the  conditions.  The  heat  may  reach  that  of  fusion,  producing  effects  that 
cannot  be  distinguished  from  those  of  fusion  from  heat  of  other  sources. 

The  obliteration  of  fossils  comes  in  an  early  part  of  the  changes;  for 
shells  are  seldom  a  twentieth  of  an  inch  thick,  while  the  grains  rendered 
crystalline  by  the  change  are  seldom  so  small  as  this.  Large  crinoid  stems 
have  the  best  chance  among  calcareous  fossils  for  preservation.  But  no 
calcareous  fossils  can  withstand  the  chemical  action  of  siliceous  solutions 
at  high  temperatures ;  for  even  strata  of  limestone  are  thinned  down  by  it. 
Trilobites,  and  other  fossils  whose  tests  are  phosphatic,  resist  longer  than 
the  calcareous. 

The  uncrystalline  rock-materials  that  undergo  regional  metamorphism.  —  It 
has  been  stated  that  fragmental  rocks  are  the  chief  kinds.  But  it  is  to  be 


HEAT  —  METAMORPHISM.  315 

observed  that  the  small  differences  among  the  varieties  of  these  rocks, 
depending  on  impurities,  or  on  the  composition  of  the  grains,  have  great 
influence  over  the  results ;  and  so  also  has  the  amount  of  moisture  present  in 
the  rocks  or  in  cavities  among  them.  Beds  of  iron  ore,  or  of  coal,  or  of  salt, 
may  be  in  a  sandstone  series. 

If  the  fragmental  rock  consists  of  quartz  grains  only,  metamorphism  can 
make  nothing  but  a  harder  sandstone,  or  quartzyte ;  while,  if  it  consists  of 
grains  of  quartz  and  feldspar,  it  may  be  converted  by  metamorpbism  into  a 
gneiss,  or  even  a  granite ;  or  if  there  is  disseminated  clayey  material,  which 
contains  no  alkali,  it  cannot  make  a  micaceous  quartzyte,  but  may  make  a 
kind  containing  the  mineral  ottrelite,  or  andalusite. 

These  examples  illustrate  the  dependence  of  the  metamorphic  products 
on  the  chemical  composition  of  the  ingredients  present,  and  show  that  specu- 
lations on  the  origin  of  the  minerals,  made  without  a  knowledge  of  the 
ordinary  impurities,  are  valueless. 

The  following  are  some  of  the  results  of  metamorphism,  arranged  under 
the  different  heads  mentioned :  — 

1.  Incipient  Metamorphism. 

These  changes  generally  involve  the  loss  of  some  volatile  or  combustible 
ingredient. 

1.  A  carbonaceous  shale  or  sandstone,  when  heated,  usually  loses  some 
mineral  gas  or  oil,  the  volatile  part  of  the  carbonaceous  material ;  and  then 
"  the  fixed'  carbon "  that  is  left  may  be  oxidized  and  so  escape  as  gas 
(being  burnt  out),  leaving  the  rock  white  (if  a  limestone,  a  white  marble) 
unless  some  other  source  of  color  is  present.  If  the  carbonaceous  material 
is  a  bed  of  coal,  the  volatile  part  may  escape,  and  the  "  fixed  carbon  "  remain 
as  a  bed  of  anthracite.  As  a  consequence  of  the  last  process,  the  coal-bed 
has  become  thinner,  owing  to  the  loss,  and  is  less  pure  in  proportion  to  its 
thickness. 

2.  The  water  in  the  rocks  is  easily  volatilized.  But  under  rock-pressure 
much  may  be  retained  at  temperatures  above  212°  F.  That  of  clays,  14  per 
cent  of  which  is  chemically  combined  in  pure  clay,  may,  under  pressure,  be 
retained  and  help  to  make,  in  low-grade  metamorphism,  hydrous  minerals,  as 
chlorite,  serpentine,  etc.  The  water  of  limonite  (the  yellow-brown  iron  oxide, 
2  Fe203  +  3  H20)  is  driven  off  at  212°,  reducing  it  to  hematite  (the  red  oxide, 
Fe203);  and  in  this  way  common  sandstones  of  yellowish,  grayish,  greenish, 
brownish,  and  other  colors  (generally  due  to  disseminated  limonite)  become 
red.  Most  colored  sandstones  redden  on  heating,  and  in  this  way  many 
sandstones  have  been  made  red.  But  at  a  higher  temperature  under  low  rock 
pressure,  the  red  oxide  coloring  a  red  sandstone  may  be  converted  into  steel- 
lustered  crystals;  or  become  reduced  to  magnetite  (Fe304);  or  combine  with 
silica  to  make  silicates  (epidote,  chlorite,  etc.)  and  by  such  means  the  red 
color  may  be  discharged. 


31o  DYNAMICAL   GEOLOGY. 

3.  The  carbonic  acid  of  limestones  is  driven  off  at  a  low  temperature,  as 
in  limekilns.     But  under  heavy  rock-pressure  the  loss  does  not  take  place  ;  for 
limestone  may  be  melted  in  a  strong  iron  flask  without  decomposition,  as 
shown  by  Sir  James  Hall  (1790) .     Again,  when  iron  carbonate  (FeO.  C02) 
is  present  in  a  sandstone,  heat  may  expel  the  carbonic   acid    (C02)   and 
leave  the  iron  to  oxidize  and  become  the  red  oxide  (Fe203).     This  is  a  second 
source  of  the  red  color  of  red  sandstones  and  shales.     But  under  pressure 
the  ore  may  be  crystallized  without  loss. 

4.  Consolidation  of  rocks  also  goes    forward    in    the    feebler   stages    of 
metamorphism.     Subjection  to   heavy  superincumbent  pressure  forces  the 
particles  into  closer  contact,  and  this   favors   consolidation   in  clays   (W. 
Spring).     The  consolidation  in  the  case  of  ordinary  shales,  even  Silurian,  as 
the  Utica  shale,  is  feeble,  unless  some  metamorphic  heat  has  given  aid. 

2.  Crystallinic   Metamorphism. 

Calcyte  (CaO.  CO.,),  or  dolomyte,  magnesian  limestone,  if  pure,  becomes 
under  metamorphic  action  a  white  crystalline  rock,  like  architectural  or 
statuary  marble,  in  which  state,  as  the  naked  eye  may  detect,  each  grain  has. 
the  cleavage  of  crystallized  calcite  or  dolomite.  The  process  is  simply  that 
of  crystallization.  It  is  a  change  without  fusion.  It  is  a  molecular  change 
solely,  like  the  change  which  takes  place  in  tempering  steel  from  fine 
to  coarse,  or  the  reverse. 

Again,  under  slow  metamorphic  action,  a  granitic  sandstone,  consisting  of 
quartz,  feldspar,  and  mica  (the  constituents  of  granite),  loses  the  worn  surfaces 
of  the  grains  and  becomes  a  granite.  The  sandstone  being  a  massive  rock,  it 
is  massive  still  —  a  true  granite,  and  not  gneiss.  A  sandstone,  consisting  of 
feldspar  and  quartz,  without  the  mica,  becomes  the  granite-like  rock  called 
granulyte.  Such  sandstones  make  up  the  Triassic  of  the  Connecticut  Valley, 

and  some  portions,  well  consolidated,  look  exceed- 
ingly  like  granite,  although  they  have  not  been 
subjected  to  the  heat  and  pressure  of  the  true 
metamorphic  process.  The  following  analysis,  by 
F.  W.  Taylor,  of  the  Connecticut  rock,  from  Port- 
land, —  the  common  building  stone,  —  shows  its 
granite-like  composition  (see  10th  Census,  Vol.  10, 
Rep.  on  Building  Stones,  page  127)  :  silica  69-94, 
alumina  13-55,  Fe2032-48,  Mn2030-70,  lime  3-09, 
soda  5-43,  potash  3-30,  moisture  1-01  =  99-50.  If 
the  granitic  sandstone  were  thin-bedded  it  might 
become  gneiss ;  and  a  shale  might  make  a  mica 
Grain  of  quartz  of  Potsdam  sand-  schist  of  like  composition.  Moreover,  in  the  in- 
n^'Tt  Ye"!"'"  tenser  stage  of  metamorphism  a  bedded  granitic 
sandstone,  instead  of  being  changed  to  gneiss  might 
become  plastic  or  fused,  and  so  lose  all  bedding  and  become  granite.  Such 


HEAT  —  MET  AMO  RPHISM.  317 

granite  is  igneous  granite,  and  if  it  is  forced  up  opened  fissures,  it  is  eruptive 
granite. 

Metamorphism  in  the  above  cases  is  simply  crystallization,  'so  far  as  there 
is  any  change ;  for  chemical  change  is  not  needed  for  the  results  mentioned. 
But  in  many  cases  it  is  even  simpler  than  stated ;  for  in  the  process  the 
grains  of  feldspar  and  quartz  may  be  only  enlarged  or  finished  out  by  surface 
additions,  in  a  crystalline  way,  conformably  to  their  crystallographic  axes. 
In  a  quartz  sandstone,  the  quartz  grains,  under  the  process,  are  made  into 
quartz  crystals  (Fig.  284)  if  there  is  space  for  it  (Sorby);  and  they  may  con- 
tinue growing  until  the  sandstone  becomes  a  compact  mass  of  quartz  rock 
(or  quartzyte)  showing  its  original  grains  only  indistinctly.  In  a  similar 
way,  the  feldspar  grains  present  in  a  rock,  and  any  hornblende  or  pyroxene 
grains,  may  be  enlarged  or  finished  out.  This  process  would  convert  a  gra- 
nitic sandstone  into  granite,  making  the  rock  without  the  heat  of  fusion 
or  plasticity.  In  California  Cretaceous  sandstones,  according  to  Becker, 
the  feldspar  crystals  made  by  metamorphic  change  occupy  the  positions  of 
previous  groups  of  grains  of  feldspar ;  and  the  same  for  pyroxene  and 
hornblende. 

A  granitic  sandstone  having  its  quartz  grains  changed  to  quartz  crystals, 
in  a  process  of  metamorphism,  becomes  thus  a  quartz-porphyry.  As  quartz 
crystals  are  usually  formed  from  siliceous  solutions  instead  of  from  fusion, 
the  occurrence  of  such  imbedded  crystals  through  the  mass  of  a  rock  is  pre- 
sumptive evidence  against  its  igneous  origin. 

3.  Paramorphic  Metamorphism. 

When  the  minerals  aragonite  and  calcite  are  present  together  in  a 
limestone  (page  69),  the  first  effect  of  metamorphic  action  is  the  conversion 
of  the  aragonite  into  calcite  —  that  is,  the  making  it  rhombohedral  in 
cleavage  structure,  like  calcite,  its  paramorph.  Crystallinic  metamorphism, 
also,  may  go  forward  simultaneously  and  make  the  rock  coarsely  crystalline. 
The  change  of  pyroxene  crystals  to  hornblende  is  a  common  example  of 
paramorphic  change.  It  has  often  gone  on  extensively,  changing  whole 
pyroxenic  rocks  to  hornblendic.  The  inner  part  of  a  crystalline  grain  of 
pyroxene  often  has  its  lines  of  cleavage  crossing  at  angles  of  87°,  the  angle 
of  pyroxene,  when  in  the  outer,  the  part  altered,  they  are  changed  to  1241°, 
the  angle  of  hornblende.  The  altered  pyroxene  was  named  uralite  (from 
the  Urals)  by  G.  Rose  (1830),  and  the  change  is  hence  called  uralitization. 
Many  Archaean  crystalline  rocks  now  hornblendic  have  been  proved,  by  such 
evidence,  to  have  been  originally  pyroxenic ;  and  so  it  is  with  many  other 
rocks,  including  some  of  igneous  origin.  Even  the  pyroxene  of  dikes  of 
doleryte  has  been  found  changed  to  hornblende. 

This  change  in  a  rock  of  the  basalt  type  (the  doleryte  of  Land's  End,  Cornwall)  was 
first  observed  by  Allport  (1876);  in  augite-syenyte  of  New  Hampshire,  by  S.  W.  Hawes 
(1878);  in  Wisconsin  Archaean  rocks,  by  Irving  and  Van  Hise  (1883).  The  mineral  hy- 


318  DYNAMICAL   GEOLOGY. 

persthene  also  occurs  altered  to  hornblende ;  cyanite  to  andalusite  ;  labradorite  and  anor- 
thite  to  saussurite.  Quartz  changes  to  tridymite,  or  to  biaxial  silica,  when  it  is  heated 
to  or  above  2200°  F.,  which  accounts  for  the  occurrence  of  tridymite  in  volcanic  rocks  ;  and 
tridymite,  or  biaxial  silica,  becomes  uniaxial  optically  at  260°  F.  ;  but  further  than  this 
it  does  not  change  on  heating. 

Pyroxene,  a  common  volcanic  mineral,  has  long  been  known  as  a  furnace  product, 
and  since  1823  as  the  result  of  the  fusion  of  its  constituents  ;  but  Deville,  in  1858,  obtained 
crystals  by  simply  heating  to  a  bright  red  heat  a  piece  of  ferruginous  Fontainebleau  sand- 
stone with  chloride  of  magnesium ;  the  crystals  of  pyroxene  cemented  the  quartz  grains 
of  the  sandstone.  Hornblende  nab  never  been  produced  experimentally  from  fusion  ;  but 
in  1890  the  Russian  chemist,  Krustchoff,  heated  together  its  constituents  for  three  months, 
at  a  temperature  of  only  900°  to  1000°  F.,  and  obtained  hornblende  in  crystals  ;  and  along 
with  them  were  crystals  of  quartz  and  of  a  light-colored  pyroxene  (diopside).  The  facts 
show  that  the  change  of  pyroxene  to  hornblende  requires  only  a  heating  of  the  rock  con- 
taining it  to  1000°  F.  It  indicates  also  that  if  a  pyroxene-bearing  rock,  on  cooling  from 
fusion,  rests  long  at  this  temperature,  it  would  probably  become  throughout  a  hornblende 
rock,  and  appear  as  if  so  primarily. 

Paramorphic  metamorphism  should  be  of  common  occurrence  ;  for  paramorphs  are 
essentially  identical  except  in  crystallizations  (pages  62,  67,  69). 

4.  Metachemic   Metamorphism. 

Through  the  chemical  work  of  metamorphism  have  been  made  nearly  all 
the  common  siliceous  minerals  among  rock  constituents,  even  many  kinds 
that  are  also  of  igneous  origin :  as  the  feldspars,  micas,  quartz,  minerals  of 
the  hornblende  and  pyroxene  group,  the  chlorites,  epidote  and  the  related 
species,  scapolites,  garnets,  tourmaline,  chrysolite,  and  many  others.  The 
older  metamorphic  and  igneous  rocks  have  been  the  chief  sources  of  the 
materials.  Even  in  formations  not  older  than  the  Cretaceous,  as  described 
in  Becker's  account  of  the  rocks  of  California,  the  results  of  metamorphism 
include  orthoclase,  albite,  oligoclase,  labradorite,  muscovite,  biotite,  horn- 
blende, pyroxene,  glaucophane,  epidote,  zoisite,  garnet,  chlorite,  serpentine, 
talc,  and  other  species. 

In  these  metachemic  changes,  without  aid  from  outside  ingredients,  feld- 
spar may  be  altered  to  hydromica^  or  mica  (muscovite),  under  metamorphic 
action  (Van  Hise).  Each  of  these  minerals  contains  silica,  alumina,  and 
potash,  but  the  mica,  a  third  less  of  silica ;  hence  a  feldspathic  or  granitic 
sandstone  may  be  made  micaceous,  and  a  feldspathic  shale  may  be  converted 
into  a  hydromica  or  mica  schist.  Hydromica  schist  is  a  common  rock  in  the 
regions  of  crystalline  rocks  of  eastern  North  America,  and  in  other  such 
regions  over  the  globe ;  and  feldspathic  sediments,  derived  from  the  abundant 
feldspar  of  these  rocks,  are  their  only  source.  For  mica  scales  float  easily  in 
transporting  waters  and  become  scattered  among  other  materials  instead  of 
being  gathered  together  into  beds.  A  felsyte  may  change  to  pinite,  as  near 
Boston  (Crosby),  which  mineral  is  essentially  a  massive  mica. 

But  if  the  shale  is  an  argillaceous  rock  without  potash,  (no  undecom- 
posed  feldspar  being  present)  it  is  very  likely  to  contain  more  or  less  iron, 
magnesia,  and  lime ;  and  then  it  has  the  elements  required  for  making  a 


HEAT  —  METAMORPHISM.  319 

chlorite  schist  or  a  hornblende  schist,  and  for  filling  such  schists  with  crystals 
of  the  silicates,  hornblende,  pyroxene,  garnet,  staurolite,  ottrelite;  or  if  free 
from  iron,  it  has  the  elements  for  making  andalusite,  sillimanite,  cyanite 
(each  Al203Si02),  silica  and  alumina,  when  no  alkali  or  other  bases  are  free, 
being  ready  to  form  these  aluminum  silicates. 

Increasing  remoteness  from  a  region  of  crystalline  rocks  favors  the  mak- 
ing of  sediments  free  from  alkali,  because  the  alkali  becomes  leached  out  of 
sediments  by  the  transporting  waters.  This  is  illustrated  a  few  miles 
west  of  New  Haven,  Conn.,  where  the  mica  schist  gradually  changes  to 
the  southward,  to  a  chloritic  hornblende  schist,  —  hornblende  and  chlorite, 
unlike  the  mica,  containing  no  potash. 

When  carbonaceous  shales  are  altered  to  mica  schist,  the  "  fixed  carbon  " 
present  (page  315)  may  become  crystallized  into  graphite;  for  graphitic 
mica  schists  are  common.  It  has  been  suspected  that  diamonds,  another 
form  of  carbon,  may  have  been  made  in  the  course  of  the  metamorphic 
changes  of  carbonaceous  shales  or  sandstones. 

Again,  if  a  dolomyte,  or  magnesian  limestone,  contains  some  silica  finely  disseminated 
through  it  as  impurity,  either  in  the  state  of  quartz  or  of  organic  silica  (Diatoms,  spicules 
of  Sponges),  metamorphic  action  may,  while  crystallizing  the  limestone,  fill  it  with  bladed 
or  radiating  crystallizations  of  tremolite  (white  hornblende)  ;  for  a  portion  of  the  dolo- 
mite (£  Ca  J.  MgO.  CO2)  might  take  the  silica  (Si02)  as  a  substitute  for  its  carbonic 
acid  (CO2),  and  thus  tremolite  (£  Ca  J  MgO.  Si02)  would  result.  When  the  dolomyte 
contains  some  iron,  as  well  as  the  silica,  actinolite  (green  hornblende)  may  form  and  in 
like  manner  be  disseminated  through  the  mass  of  the  rock,  instead  of  tremolite.  Under 
similar  circumstances,  at  a  higher  temperature,  white  pyroxene  which  has  the  same 
composition  as  tremolite,  or  green  pyroxene,  which  has  the  composition  of  actinolite, 
may  be  formed  in  stouter  crystallizations. 

If  clayey  impurities  are  present  in  the  limestone  (these  consisting  of  silica  and  alu- 
mina, with  or  without  iron  or  magnesia),  the  limestone  may  become  filled  with  garnets  and 
other  silicates.  An  Eocene  limestone,  in  the  Ligurian  Apennines,  much  contorted  and  in 
contact  with  diabase,  gabbro,  etc.,  contains  crystals  of  the  soda-feldspar  albite  ;  and  inside 
of  the  crystals  there  are  the  siliceous  tests  of  Radiolarians  (genera  Ethmosphsera,  Helios- 
phsera,  and  others),  suggesting  that  possibly  the  silica  of  the  albite  was  of  organic  origin. 
(A.  Issel,  1890.) 

Chrysolite  consists  of  silica  41-4,  magnesia  50-9,  iron  protoxide  7-7.  In  the  rocks 
it  is  often  found  changed  to  serpentine,  which  consists,  in  100  parts,  of  silica  43-5, 
magnesia  43-5,  water  13.  The  iron  protoxide  and  some  magnesia  are  here  rejected 
and  water  received  ;  and  usually  the  iron  stays  about  or  within  the  serpentine,  as  a  cloud 
of  black  grains  or  a  few  black  crystals  of  magnetite.  So,  also,  the  magnesian  silicates, 
pyroxene,  hornblende,  chondrodite,  chlorite,  and  other  species,  occur  changed  to  serpentine. 
When  such  a  change  happens  on  a  large  scale,  a  chrysolite  rock,  or  pyroxenic  rock,  or 
hornblendic  rock,  etc.,  becomes,  in  part  or  wholly,  a  serpentine  rock.  In  a  similar  way, 
pyroxene,  or  hornblende,  or  garnet,  may  be  changed  to  chlorite,  or  to  epidote,  etc.,  labra- 
dorite,  or  anorthite  (G  =  2-7)  to  saussurite  (G  =  3  -  3-5). 

The  pure  amorphous  serpentine  often  has  parallel  cracks  (apparently  due  to  contrac- 
tion on  drying),  which  are  filled  with  fibrous  serpentine  (amianthus,  or  asbestos)  ;  and 
when  the  cracks  are  very  thin  and  numerous,  and  are  filled  with  calcite  or  dolomite,  the 
specimens  often  have  the  aspect  and  general  structure  of  the  so-called  Eozoon  of  Archaean 
rocks. 


320  DYNAMICAL   GEOLOGY. 

Again,  dikes  of  trap  and  other  igneous  rocks  have  undergone  metachemic  alteration 
through  interior  heated  vapors  which  ascended  with  the  rock,  making  the  rock  hydrous 
and  producing  other  changes,  and  by  the  same  means  its  vesicles  have  often  been  filled 
with  secondary  minerals  made  out  of  the  materials  of  the  rock. 

Mineral  springs  are  often  referred  to  as  a  source  of  outside  ingredients. 
But,  for  regional  work,  such  springs  should  have  a  wide  distribution ;  other- 
wise the  effects  would  be  local.  One  mineral  spring,  rich  in  salts  of  soda 
and  magnesia,  has  already  been  mentioned  as  the  great  one  of  the  world  — 
the  ocean.  Nearly  all  the  sedimentary  rocks  were  made  in  it,  or  have  at 
some  time  been  submerged  in  it.  Moreover,  there  is  evidence  that  salt 
water  has  an  extensive  subterranean  distribution,  in  the  fact  that  a  large 
part  of  the  borings  for  gas  and  oil,  which  have  been  made  in  recent  years, 
have  encountered  salt  water  below  depths  of  1000  or  2000  feet  —  depths  too 
great  to  be  made  fresh  by  subterranean  drainage.  Further,  formations  of  sev- 
eral geological  periods  contain  great  beds  of  rock  salt  that  were  beyond  doubt 
of  oceanic  origin. 

Associated  with  the  salt,  or  in  the  same  series  of  rocks,  there  are  some- 
times deposits  of  magnesian  salts  of  like  oceanic  origin ;  and,  more  spar- 
ingly, of  potash  salts;  and  also  of  boron  salts,  for  the  magnesium  borate, 
boracite,  occurs  in  salt  mines,  and  other  boron  salts  exist  in  hot  springs, 
sometimes  in  volcanic  emanations,  —  facts  that  point  to  a  marine  source. 
Moreover,  traces  of  borates  have  been  detected  in  the  ocean's  waters. 
The  beds  of  salt  and  the  briny  layers  are  interstratined,  sometimes  in 
many  alternations,  with  shales,  sandstones,  and  limestones ;  and  it  is 
natural,  therefore,  that  the  soda  and  magnesia  should  be  forced  to  take  part 
in  any  chemical  changes  the  associated  formations  might  undergo.  Meta- 
morphic  work  may  have  derived  much  soda  from  this  source  for  making 
soda-lime  feldspars,  as  oligodase  and  labradorite;  supplies  of  magnesia  for 
forming  hornblende  and  black  mica ;  smaller  supplies  of  potash  for  ortho- 
clase-making ;  and  still  smaller  of  boron,  yet  enough  to  account  for  the  wide 
distribution  of  tourmaline,  whose  constituents,  apart  from  the  boron,  differ 
little  from  those  of  garnet,  —  a  mineral  that  is  common  in  mica  and  chlorite 
schists,  crystalline  limestone,  quartzyte,  and  other  rocks. 

The  wide  distribution  of  alkaline  waters  over  the  Great  Basin  (page  119)  suggests 
another  available  source  of  materials,  and  especially  of  soda  and  magnesia.  But  such 
regions  are  a  consequence  of  the  absence  of  drainage,  and  could  exist  only  in  great  lands 
like  continents  ;  they,  therefore,  belong  only  to  the  latter  end  of  geological  time. 

The  following  are  examples  of  metachemic  work  in  crystalline  rocks.  Massive  talc, 
called  rensselaerite,  at  Fowler,  Dekalb,  and  other  places  in  northern  New  York,  made  from 
pyroxene,  whose  cleavage  it  has  ;  a  pinite,  called  gieseckite,  at  Diana,  N.  Y.,  and  in  Green- 
land, made  from  crystals  of  nephelite,  the  form  remaining ;  pinite  also  from  scapolite, 
at  Franklin,  N.  J.  (algerite)  and  Arendal,  Norway  ;  chlorite  in  many  localities,  from 
garnet  (crystals  being  sometimes  chlorite  outside  only,  and  sometimes  throughout), 
pyroxene,  hornblende,  etc. ;  mica  and  epidote  from  scapolite,  at  Arendal,  Norway ; 
and  feldspar  from  scapolite,  at  Bamle,  Norway;  epidote  from  biotite-mica ;  diaspore, 
margarite,  and  other  species,  from  corundum.  In  a  large  granitic  vein  at  Branchville, 


HEAT  —  METAMORPHISM.  321 

Conn.,  where  spodumene  crystals  occur  a  yard  long,  the  alteration  of  the  spodumene,  a 
lithia-alumina  bisilicate,  has  produced  (as  described  and  explained  by  G.  J.  Brush  and 
E.  S.  Dana,  1878-1880)  eucryptite,  a  different  lithia-alumina  silicate  ;  also  microcline  or 
potash  feldspar,  muscovite  mica,  killinite,  which  are  potash -bearing  silicates,  free  of  lithia  ; 
also  the  soda  feldspar,  albite,  each,  excepting  killinite,  in  large  crystallizations.  Besides, 
it  is  evident  that  the  mica  and  albite  were  unitedly  results  of  change  from  the  spodumene 
(the  mica,  through  the  eucryptite  as  a  first  step),  since  they  occur  in  minute  scales 
together,  making  half  an  inch  or  more  of  the  outside  of  the  spodumene  crystals,  the  material 
looking  so  much  like  a  single  simple  mineral  that  it  was  first  (1867)  named  as  such,  cyma- 
tolite.  In  addition  to  these  changes,  half  a  dozen  phosphates  were  made  out  of  triphylite 
(an  iron-manganese  phosphate),  part  by  combination  with  the  lithia  and  other  bases  set 
free  from  the  alteration  of  the  spodumene  ;  also  uranium  minerals  were  made  from 
uraninite. 

In  mineral  veins  a  still  wider  range  of  changes  has  taken  place,  through  the 
metallic  and  other  vapors  that  have  ascended  the  opened  fissures  and  the  waters  that 
have  descended. 

Since  most  crystalline  metamorphic  rocks  are  only  recrystallizations  of 
the  detritus  from  such  rocks,  the  feldspar  and  quartz  being  earlier  feldspar 
and  quartz,  and  so  with  many  other  minerals,  and  since  the  ocean's  waters 
have  distributed  its  salts  among  the  formations,  it  is  not  necessary  to  appeal 
for  producing  silicates  to  "  springs  bringing  up  mineral  waters  from  below." 
There  is  no  place  in  geology  for  the  crenitic  hypothesis  of  Hunt  (1884),  so 
named  from  the  Greek  for  a  fountain  or  spring. 

5.    Endo-Crystallic  Metamorphism. 

In  crystallized  limestones,  either  calcyte  or  dolomyte,  the  crystalline 
grains  have  commonly  a  compound  twin-structure,  which  is  attributed  to  the 
pressure  among  the  grains  attending  the  original  crystallization.  Another 
effect  of  pressure  is  the  breaking  and  displacement  of  crystals  in  rocks. 

Professor  J.  W.  Judd  and  others  have  drawn  especial  attention  to  the  changes  that 
have  taken  place  within  the  crystalline  grains  of  rock  through  pressure,  without  aid  from 
rock-movements  as  a  source  of  heat,  endeavoring  to  distinguish  them  as  far  as  possible 
from  metamorphic  work  of  other  kinds.  Like  the  compound  twinning  in  the  grains  of 
crystalline  limestone,  the  lamellar  twinning  in  a  triclinic  feldspar,  including  microcline,  is 
referred  to  stresses  attending  crystallization. 

To  the  same  cause  are  to  be  attributed  the  bronzy  luster  developed  by  incipient  change 
in  pyroxene  and  hypersthene,  arising  from  the  production  interiorly  of  minute  points  of 
mineral  material  in  parallel  planes — an  effect  called  by  Judd  schillerization  —  and  its 
usual  accompaniment,  a  laminated  or  diallage-like  structure.  Of  similar  origin  are  changes 
in  orthoclase,  giving  its  crystals  an  aventurine  or  iridescent  character,  or  a  new  direction 
of  cleavage,  as  in  the  variety  murchisonite,  or  interlaminations  of  albite  or  of  some  other 
feldspar,  as  in  perthite.  Related  changes  occur  also  in  other  species. 

6.    Heat  used  in  Metamorphism. 

The  heat  for  most  metamorphic  results  was  probably  comparatively  low, 
or  between  500°  F.  and  1200°  F.     It  was  heat  in  slow  and  prolonged  action, 
operating  through  a  period  that  is  long,  even  according  to  geological  measure. 
DANA'S  MANUAL  —  21 


322  DYNAMICAL   GEOLOGY. 

A  low  temperature,  acting  gradually,  during  an  indefinite  age  —  such  as  ge- 
ology proves  to  have  been  required  for  many  of  the  great  changes  in  the 
earth's  history  —  would  produce  results  that  could  not  be  otherwise  brought 
about,  even  through  greater  heat. 

The  lower  limit  of  temperature  is  sometimes  placed  much  below  300°  F. ; 
and  for  consolidation  it  may  be  rightly  so.  But  there  is  definite  evidence 
that  it  generally  exceeded  this.  In  the  great  faults  of  the  Appalachians, 
10,000  feet  or  more  in  extent,  Lower  Silurian  limestones  are  brought  up  to 
view,  containing  their  fossils,  and  not  metamorphic  ;  and  in  Nova  Scotia  the 
coal  formation,  though  15,000  feet  thick,  is  not  metamorphic  at  base.  Taking 
the  increase  of  temperature  in  the  earth's  crust  at  1°  F.  for  60  feet  of  descent, 
10,000  feet  of  depth  would  give  220°  F.  as  the  temperature  of  the  limestone 
before  the  faulting ;  and  1°  F.  per  60  feet  of  descent  must  be  short  of  the 
rate  that  obtained  in  the  Carboniferous  age. 

Regional  metamorphic  rocks  are  upturned  rocks,  rocks  that  have  been 
subjected  to  the  faulting,  crushing,  and  flexing,  attending  mountain-making. 
Hence,  in  accordance  with  the  explanations  on  page  385,  they  are  rocks 
which  have  been  subjected  to  pressure  and  movement  on  a  vast  scale,  and 
thereby  to  heat  made  just  where  it  was  needed  for  metamorphic  work. 
Mountain-making  movements  might  be  so  slow  that  the  heat  would  become 
mostly  dissipated  instead  of  accumulating.  But  the  rocks  upturned  were 
generally  10,000  to  30,000  feet  thick  or  more,  and  great  pressure  and  high 
temperatures  should  be  expected  from  movements  so  vast  over  regions 
exceeding  sometimes  a  thousand  miles  in  length. 

The  heat  for  metamorphism  appealed  to  is  heat  of  a  dynamical  source, 
and  the  conditions  are  those  that  will  produce  its  maximum  effects. 

The  movement  of  rocks  along  fracture-planes  in  faulting  produces  heat ; 
but  only  occasionally,  in  connection  with  the  greater  upthrust  or  onthrust 
faultings,  is  it  sufficient,  unless  reinforced  from  accompanying  upturnings, 
for  metamorphic  action  in  the  walls  of  the  fracture.  The  changes  will 
seldom,  if  ever,  extend  so  far  as  to  obliterate  the  plane  of  faulting,  or  to 
disguise  the  fact  that  the  heat  has  a  local  source  along  this  plane,  provided 
the  faulting  is  not  attended  with  extensive  crushing  of  the  adjoining  rock. 
As  such  a  fracturing  of  the  rocks  is  commonly  of  the  shearing  kind,  the 
altered  band  along  the  fault-plane  is  called  a  shear-zone. 

The  earth's  internal  heat  has  always  been  a  contributor  to  the  heat  of 
the  earth's  crust,  and  much  more  so  formerly  than  now,  and  would,  there- 
fore, have  supplemented  largely  the  heat  generated  by  friction.  But  the 
alteration  of  sediments  by  the  heat  coming  up  from  the  earth's  interior 
alone  is  proved  by  many  facts  to  have  been  inadequate  for  much  more,  even 
during  the  later  Paleozoic,  than  the  solidification  of  the  rocks.  Besides 
those  mentioned  above,  it  may  be  added  that  in  the  South  Wales  coal-field 
the  Carboniferous  limestone,  although  covered  by  other  rocks  to  a  depth  of 
10,000  to  12,000  feet,  is  unaltered.  (Geikie.) 

The  great  agent  of  metamorphic  change  is  heated  moisture;  and  for  the 


HEAT  —  METAMORPHISM.  323 

higher  grades  of  metamorphism,  moisture  at  a  temperature  that  made  it 
superheated  steam.  In  the  state  of  steam  it  spreads  through  the  rocks 
with  all  the  chemical  energy  derived  from  its  high  temperature,  a  destroyer 
of  cohesion,  a  powerful  solvent,  and  a  promoter  of  decompositions  prepara- 
tory to  recompositions. 

The  making  of  deposits  of  silica  in  the  form  of  quartz  or  opal  does  not 
require  high  heat,  as  already  explained  (page  135).  In  addition  to  the  facts 
there  stated,  it  may  be  added  that  geodes  of  chalcedony  and  agate,  8  to  10 
inches  in  diameter  and  of  modern  origin,  come  from  Florida,  that  are  the 
remains  of  hemispherical  masses  of  coral,  the  exterior  still  showing  the  stars 
of  coral,  while  the  interior  is  a  great  agate-lined  cavity ;  they  were  made  by 
the  siliceous  waters  of  the  region,  and  it  is  not  certain  that  the  waters  were 
even  warm.  J.  Arthur  Phillips  found  crystallized  quartz  and  chalcedony 
among  the  recent  deposits  of  Borax  Lake,  in  Lake  County,  north  of  San 
Francisco,  and  at  Steamboat  Springs,  in  Nevada ;  and  Le  Conte  and  Becker 
have  reported  other  similar  facts.  Daubree  detected  quartz  in  the  form  of 
chalcedony  among  the  deposits  of  the  hot  waters  of  Plombieres.  It  should 
be  considered,  further,  that  the  quartz  which  makes  the  flint  and  chert  of 
the  world,  and  has  silicified  the  fossils  of  many  strata,  was  dissolved  by  cold 
waters ;  it  was  mostly  in  the  opal  state  when  dissolved,  but  was  deposited  in 
the  state  of  quartz.  Thus  the  solidification  of  rocks  by  means  of  silica  is  an 
easy  effect  in  the  presence  of  hot  moisture,  and  but  little  heat  is  necessary. 

Many  experiments  of  recent  years  illustrate  the  efficiency  of  superheated 
steam  in  confined  spaces  or  under  pressure.  Mr.  J.  Jeffrys,  in  1840,  sub- 
jected some  feldspathic  and  other  siliceous  minerals  to  a  current  of  steam 
inside  of  a  kiln  made  for  vitrifying  brown  stone-ware,  and  with  them  a  few 
articles  of  the  stone-ware.  At  a  full  red  heat,  little  effect  was  produced ;  but 
above  that  of  fused  cast  iron,  there  was  rapid  erosion,  and  in  ten  hours 
"  more  than  a  hundredweight  of  mineral  matter  had  been  carried  away  in 
the  vapors."  Daubree,  having  inclosed  a  little  water  in  a  strong  glass  tube 
and  subjected  it  to  a  temperature  of  750°  F.  (400°  C.)  for  several  weeks, 
obtained,  besides  a  hydrated  silicate  allied  to  the  zeolites,  quartz  in  well- 
defined  crystals,  and,  in  another  case,  perfect  crystals  of  the  light-colored 
variety  of  pyroxene,  called  diopside.  The  glass  was  completely  dissolved 
and  used  in  making  the  crystals.  A  clay,  from  near  Cologne,  used  in  mak- 
ing crucibles,  heated  in  the  glass  tubes,  became  charged  with  scales  of  a 
mica  or  chlorite  (the  quantity  being  too  small  for  an  analysis).  Crystals 
of  the  feldspar,  orthoclase,  occur  in  the  cavities  of  some  igneous  rocks  in 
the  copper  region  of  Lake  Superior  as  a  secondary  product,  and  the  accom- 
panying facts  make  it  certain  that  it  was  made  by  means  of  heated  moist- 
ure. But  experiments  in  closed  tubes  containing  the  ingredients  and  water 
have  succeeded  in  making  orthoclase  and  albite,  with  also  tridymite  (Haute- 
feuille,  Friedel  and  Sarrasin),  while  dry  heat  has  always  proved  a  failure. 
Experiment  has  been  successful  in  obtaining,  by  fusion,  the  feldspars,  oligo- 
clase,  labradorite,  and  anorthite,  and  also  the  rocks  containing  them. 


324  DYNAMICAL   GEOLOGY. 

The  lime-soda  feldspars,  labradorite  and  oligoclase,  and  the  lime  feldspar,  anorthite, 
were  obtained  in  crystals,  from  the  fusion  together  of  their  constituents,  by  Fouque  and 
Levy  in  1878. 

Two  days  of  fusion  only  were  required  for  labradorite.  They  have  also  produced  by 
similar  methods  the  rocks  augite-andesyte,  doleryte,  basalt,  and  others.  The  augite- 
andesyte  was  made  by  fusing  together  3  parts  of  oligoclase  and  1  of  augite,  and  it  con- 
tained octahedrons  of  magnetite  formed  at  the  expense  of  part  of  the  augite.  Doleryte 
was  obtained  in  like  manner  by  substituting  labradorite  for  oligoclase.  Such  experiments 
prove  that  these  rocks  may  be  made  from  the  constituents  by  metamorphic  methods,  if 
the  heat  is  sufficient  for  fusion  ;  and  other  facts  leave  scarcely  a  doubt  that  they  may  be 
formed  also  at  lower  metamorphic  temperatures. 

Hawaiian  caves,  made  by  the  flowing  away  of  the  lava  after  it  was  crusted 
over,  and  hot  with  the  heat  that  was  left  by  the  lavas,  contain  long  stalactites 
of  basalt,  with  isolated  crystals  of  the  feldspar,  pyroxene,  and  magnetite,  in 
their  cavities,  as  explained  on  page  295.  In  this  case,  there  was  no  decom- 
position and  recomposition,  but  simply  solution,  transfer,  and  recrystallization. 
The  heat  was  that  left  by  the  passing  lava ;  for  there  was  no  other  possible 
source ;  and  it  was  less  than  that  of  fusion,  for  much  had  been  lost  by  the 
expansion  of  the  superheated  vapor  as  it  escaped.  The  vapors  would  have 
contained  sulphur,  or  sulphurous  acid,  and  perhaps  other  ingredients,  but 
beyond  increasing  solvent  powers,  if  this,  these  aids  had  nothing  to  do. 

These  facts  are  eminently  instructive  as  to  the  powers  of  superheated 
steam.  It  can  do  transfer  work,  take  up  labradorite,  pyroxene,  and  mag- 
netite at  one  place,  and  transfer  and  deposit  them  crystallized  in  another. 
The  facts  above  stated  also  prove  that  superheated  steam,  at  a  high  tem- 
perature, may  produce  that  plastic  state  of  a  rock,  which  is  like  fusion  in 
any  other  way  in  its  ability  to  obliterate  all  previous  structural  features, 
and  which,  therefore,  could  make  granite  out  of  materials  that  otherwise  would 
have  the  bedding  of  a  gneiss. 

At  Birmingham,  Conn.,  10  miles  west  of  New  Haven,  the  porphyritic  gneiss  of  the 
region  comes  up,  in  one  place,  through  the  gneiss  and  mica  schist,  as  a  broad  and  nearly 
vertical  vein,  or  dike,  of  porphyritic  granite  —  a  rock  like  the  bedded  gneiss,  except  in  the 
absence  of  bedding,  and  in  its  vein-like  position.  It  is  plainly  a  result  of  the  plastic  con- 
dition of  the  rock  in  the  vicinity  of  a  fracture.  In  cases  of  veins  of  fine-grained  granite, 
it  is  always  a  question  to  be  considered  whether  it  is  not  the  plastic  granite  of  a  region 
of  metamorphism  rather  than  vein-made  granite,  or  that  of  eruption  from  a  deep-seated 
source.  Vein  granite  is  usually  coarsely  crystalline,  and  consequently  irregular  in  its 
grain.  If  the  granite  of  a  narrow  dike,  or  vein,  intersecting  any  rock  is  crystalline  granu- 
lar to  its  wall,  the  evidence  is  conclusive  that  the  inclosing  rock  was  hot,  and  it  is  almost 
certain  that  the  conditions  when  it  was  formed  were  those  of  metamorphism. 

Further,  the  pressure  which  is  so  enormous  in  some  cases  of  mountain- 
making,  increases  the  solvent  power  of  hot  moisture,  and  promotes  the  weld- 
ing of  grains  by  the  closeness  of  the  contact. 

Variations  in  degree  of  heat  and  amount  of  moisture.  —  The  metamorphic 
effects  in  a  region  are  greatly  varied  by  differences  in  temperature,  and  in 
amount  of  moisture.  The  region  has  necessarily  its  area  of  maximum  heat, 


HEAT  —  METAMORPHISM.  325 

and  large  upturning,  and  its  border  of  lower  heat ;  for  it  is  surrounded  by 
regions  of  little  or  no  heat.  There  will  be,  therefore,  gradation  in  effects  in 
one  direction  or  another. 

But  it  is  to  be  noted  that  the  heat  generated  in  metamorphic  regions  by  the  movements 
does  not  vary  with  the  variations  in  dip  of  the  several  successive  plications,  but  with  the 
general  character  of  the  great  range  of  flexures  and  their  relation  to  the  direction  of  the 
chief  source  of  the  movements.  The  cause  is  regional  in  its  action,  not  local.  The  suc- 
cessive flexures  may  vary  from  vertical  anticlines  and  synclines  to  those  of  very  low  angle, 
having  nearly  horizontal  bedding  for  a  mile  or  more  along  the  axial  part  of  the  plications  ; 
and  yet  the  gneiss  or  mica  schist  of  the  beds  shows  no  corresponding  change  in  texture. 
This  fact  is  well  illustrated  in  the  Taconic  Range,  and  in  the  crystalline  region  along  the 
Housatonic  River  east  of  Derby,  Conn. 

Where  the  heat  is  of  low  grade,  the  moisture  present  may  partly  remain 
as  a  constituent  of  the  new  rocks  ;  but  under  intenser  conditions,  only  anhy- 
drous kinds  will  be  made.  A  penumbra  of  hydromica  and  chlorite  schists, 
with  coarse  mica  schists  and  gneiss  making  the  hotter  belt  beyond,  is,  there- 
fore, to  be  looked  for. 

Going  from  New  Haven,  Conn.,  20  miles  westward,  where  the  rocks 
make  a  single  conformable  series  in  anticlines  and  synclines,  there  is  a  reg- 
ular gradation  from  chloritic  and  hydromica  schists,  with  gray  slightly  crys- 
talline limestone,  to  mica  schists  and  gneiss,  and  coarsely  porphyritic  gneiss ; 
and  at  17  miles,  the  gneiss  and  mica  schist  overlie  a  stratum  of  coarsely  crys- 
tallized limestone  in  a  very  low  and  long  syncline.  In  a  similar  manner, 
the  Taconic  metamorphic  region  on  the  borders  of  New  England  and  New 
York,  as  already  explained,  increases  in  grade  of  metamorphism,  both  from 
north  to  south  and  from  west  to  east. 

Again,  the  Bernardston  Devonian  rocks,  of  one  epoch  of  metamorphism, 
mentioned  on  page  310,  bear  on  this  point;  and  so  do  the  facts  from 
California,  that  in  the  altered  Cretaceous  series  the  rocks,  diabase,  dioryte, 
gabbro  occur  as  results  of  metamorphism,  and  that  the  feldspars,  labradorite, 
and  oligoclase,  are  found  even  in  half-altered  sandstone.  (Becker,  1888.) 
It  is  thus  plain  that  among  metamorphic  rocks,  as  well  as  those  of  deep- 
seated  igneous  origin,  kind  of  rock  and  grade  of  crystallization  are  not  evi- 
dence of  differences  in  geological  age. 

In  some  cases  the  bedding  of  rocks  has  been  obliterated  by  metamorphic 
action,  without  their  reaching  the  condition  of  plasticity,  in  consequence  of 
a  tendency  to  promiscuous  crystallization  in  the  grains  of  the  constituent 
minerals.  This  is  true,  for  the  most  part,  of  rocks  consisting  of  hornblende 
alone  (hornblendyte),  hornblende  and  a  feldspar  (dioryte,  labradioryte), 
feldspar  (felsyte),  feldspar  and  quartz  (granulyte  or  mica-less  granite, 
quartz-felsyte),  serpentine,  and  some  others. 

A  bedded  structure  may  also  be  obliterated  by  the  soldering  together  of 
layers,  when  the  rock  is  subjected  to  heavy  pressure,  and  all  evidence  of  it 
may  disappear,  unless  the  layers  differ  in  color  or  constitution;  as  has 
happened  in  a  portion  of  the  marble  of  Rutland,  Vt.,  and  in  other  cases, 


326  DYNAMICAL   GEOLOGY. 

where  a  pure  limestone  is  upturned  at  a  high  angle,  —  this  position  being 
evidence  of  its  subjection  at  some  time  to  heavy  pressure. 

The  heat  for  the  changes  in  granitic  veins,  like  the  Branchville,  may 
Lave  been  produced  by  friction  from  an  up  or  down  movement  along  the 
vein ;  and  the  same  is  probably  true  for  the  bed  of  iron  ore  at  Brewster,  in 
eastern  New  York ;  for  veins,  and  also  ore-beds  when  they  are  nearly  vertical, 
are  planes  of  weakness.  But  whether  the  movement  occurred  at  the  epoch 
of  mountain-making  at  the  close  of  the  Lower  Silurian,  or  at  some  other  simi- 
lar epoch,  is  unknown. 

Relations  of  metamorphic  and  igneous  rocks.  —  The  earth's  interior  source 
of  heat  has  had  much  to  do  in  geological  history  with  metamorphism  as  well 
as  with  igneous  ejections.  The  depth  to  the  region  beneath  the  earth's 
surface  having  a  temperature  near  the  fusing  point  of  the  rocks  has 
increased  with  the  progress  of  the  geological  eras;  the  amount  of  meta- 
morphism has  correspondingly  decreased  through  the  ages. 

In  early  Archaean  time  the  region  of  fusion  was  at  the  surface,  and  in 
the  later  part,  before  solidification  was  complete,  it  was  not  far  below  the 
surface.  Great  stratified  formations  had  then  already  been  made  —  30,000 
feet  in  thickness  at  least,  and  some  have  said  twice  this,  or  more.  A 
temperature  close  to  that  of  fusion  may  then  have  been  within  this  pile  of 
deposits  (page  258,  paragraph  c),  so  that  but  little  addition  to  the  heat  from 
subterranean  movements  would  have  produced  not  only  ordinary  metamor- 
phic effects,  but  also  fusion  of  portions  of  the  sediments,  making  granite, 
gabbro,  and  other  igneous  rocks. 

Metamorphic  work  was  extensively  carried  on  at  the  close  of  the  Lower 
Silurian  in  eastern  North  America,  and  igneous  rocks  were  among  the 
metamorphic  results ;  it  was  much  less  extensive  at  the  close  of  Paleozoic 
time,  and  later  than  this  it  is  not  known  to  have  occurred.  In  western 
North  America,  in  California,  however,  the  results  of  heat  were  large  even 
in  the  later  part  of  Mesozoic  time.  We  may  account  for  this  difference 
between  the  two  sides  of  the  continent,  perhaps,  by  the  fact  that  the  Pacific 
border  had  already  become  a  region  of  extensive  volcanic  action,  —  evidence 
that  the  depth  to  great  heat  was  unusually  small. 

On  the  contrary,  volcanic  action  has  increased  through  the  ages.  There 
is  no  good  reason  for  believing  that  there  was  much  volcanic  or  deep-seated 
igneous  action  in  Archaean  time.  The  earth  had  then  its  granites,  its  gabbros, 
its  syenytes,  and  other  igneous  rocks ;  but  no  petrological  study  can  show 
whether  the  fusion  was  among  the  results  of  metamorphic  action  or  not. 

In  this  connection  it  is  an  instructive  fact  that  in  eastern  North  America, 
at  epochs  when  there  was  the  greatest  amount  of  friction  and  crushing, — 
those  of  the  making  of  the  Green  Mountains  and  Appalachians,  —  no  vol- 
canoes were  made,  and  little  took  place  in  the  way  of  eruptions  through 
fissures ;  the  conditions  were  largely  those  of  the  past.  But  at  an  epoch  in 
Mesozoic  time,  when  there  was  almost  no  flexing  of  the  rocks,  and  only  low 
monoclinal  uplifts,  extensive  dolerytic  eruptions  occurred  at  intervals  for 
1000  miles  along  the  Atlantic  border. 


HEAT.  327 

The  determination  of  the  depth  of  an  igneous  source  is  possible,  if  at  all, 
only  by  geological  investigation.  Petrology  can  prove  a  rock  to  be  igneous 
and  eruptive ;  but  it  cannot,  except  in  some  obvious  volcanic  cases,  prove 
that  it  is  not,  at  the  same  time,  metamorphic. 

The  statement  that  "massive  crystalline  rocks  are  igneous"  expresses  nothing  as  to 
their  rnetamorphism,  and  especially  when  it  relates  to  the  older  crystalline  rocks  of  the 
globe  ;  and  the  occurrence  of  a  deposit  of  hematite  or  magnetite  in  gabbro,  syenyte,  or 
any  related  rock,  is  nothing  against  the  origin  of  the  magnetite  as  a  metamorphic  sedi- 
ment. The  igneous  granite  of  metamorphic  origin  often  contains  masses  and  strips  of 
schists,  from  a  few  inches  to  many  rods  in  length,  which  are  pieces  broken  from  the 
associated  schistose  formations,  in  the  course  of  the  upturning  and  metamorphism.  Such 
"  inclusions  "  do  not  occur  in  igneous  rocks  of  other  modes  of  origin  ;  the  ejections  along 
fractures  or  vents  break  off  pieces,  sometimes  1000  cubic  feet  in  size  ;  but  long  strips  of 
schist  show  that  the  schistose  beds  were  part  of  the  formation  that  became  generally 
plastic  or  fused. 

The  production  of  metamorphic  change  by  mechanical  force  without  heat 
has  been  proved  by  the  experiments  of  M.  Carey  Lea  on  salts  of  silver  (Am. 
Jour.  Sc.,  1893,  A.  Harker,  Geol  Mag.,  June,  1894).  Shearing  force,  or 
trifruration,  produces,  without  the  development  of  heat,  a  change  which  heat 
will  not  produce,  and  more  effectively  than  simple  pressure. 


V.    MINERAL  VEINS,  LODES,  LOCAL   ORE  DEPOSITS. 

Veins  occur  in  rocks  of  all  ages  and  of  all  kinds.  They  are  the  fillings 
of  fissures  or  of  open  spaces  made  in  any  way  —  exclusive  of  those  called 
dikes,  which  are  due  to  intrusions  of  melted  rock.  The  materials  are  usually 
crystalline;  and  among  the  kinds  are  included  a  large  part  of  the  stony 
minerals  and  gems  of  the  world  as  well  as  most  of  its  ores,  those  of  iron 
excepted. 

FISSURES,  FORMS  OF  VEINS. 

1.   A  Brief  Review  of  the  Way  of  Making  Fissures. 

Fissures  for  vein-making  have  been  produced :  — 

(1)  By  contraction  on  drying  :  examples  of  which  are  mud-cracks  (for  the  fillings  of 
mud-cracks  are  vein-like  in  formation);  the  cracks  in  many  limestone  concretions  (page 
97);  the  cracks  in  an  argillaceous  stratum  or  in  its  more  argillaceous  layers,  which  are 
limited  to  the  layer. 

(2)  By  contraction  on  cooling :  either  cooling  from  fusion,  as  in  igneous  rocks,  or 
cooling  from  the  heat  attending  metamorphism. 

(3)  By  subterranean  movements :  to  some  extent  the  lighter  movements  following  un- 
derminings and  ordinary  earthquakes,  but  preeminently  the  movements,  light  and  heavy, 
that  have  attended  mountain-making  ;  movements  that  flexed  strata  10,000  to  30,000  feet 
or  more  thick,  over  regions  often  hundreds  of  thousands  of  miles  in  area,  sometimes 
raising  the  rocks  to  vertical ity,  or  shoving  up  the  strata  along  fractures  for  miles,  besides 
making  fissures  and  opened  spaces  in  all  parts  of  the  disturbed  formations. 


328 


DYNAMICAL   GEOLOGY. 


(4)  By  the  disruptive  or  expansive  action  of  vapors :  as  of  vapors  attending  volcanic 
action ;  resulting  not  only  in  fissures,  but  also  in  vesicles  or  cavities  in  an  ejected  igneous 
rock,  or  along  the  walls  of  the  dikes. 

(5)  Corroding  vapors  or  solutions  rising  in  a  fissure  have  sometimes  enlarged  the 
fissure  in  some  parts  or  made  open  spaces,  especially  when  the  rock  was  a  limestone ; 
thus  large  chambers  have  been  excavated  in  this  yielding  rock  for  the  reception  of  min- 
erals and  ores. 

(6)  Porous  strata  have  taken  in  vein-material  in  proportion  to  their  porosity. 

(7)  Caverns,  however  made,  have  become  occupied  with  vein-material. 

2.    Forms  and  Kinds  of  Fissures. 

Fissures  intersect  strata  vertically  or  obliquely  or  make  a  network.  The 
angle  which  the  plane  of  a  vein  makes  with  the  vertical  is  called  the  hade  of 
the  vein;  the  hanging  wall  is  the  upper  wall  in  an  oblique  vein,  and  the 
opposite  is  the  foot  wall. 

287. 


285. 


286. 


VEINS.  —  Fig.  285,  two  simple  veins ;  286,  two  veins,  one  faulted ;  287,  a  network  of  quartz  veins  intersecting 

schist,  the  slab  5  feet  square. 

In  the  case  of  upturned  rocks,  veins  may  either  cut  across  the  beds,  or 
occupy  spaces  between  them.  Such  interstitial  veins  (Figs.  287,  288,  290) 
are  very  common  in  slaty  and  schistose  rocks,  because  forces  below  can  more 
easily  open  such  spaces  than  make  fractures  across  the  beds ;  for  it  is  fol- 


288. 


289. 


290. 


291. 


W! VI 


Interstitial  veins. 


lowing  the  grain  of  the  rock.  Such  an  opened  space  may  continue  for  some 
distance  between  the  bedding,  and  then  cut  across  to  another  plane  of  bed- 
ding, and  so  on,  the  mean  direction  being  that  which  the  space  would  have 


HEAT  —  VEINS. 


329 


292. 


followed  under  the  pressure  in  action,  if  the  rock  had  had  no  grain.  Or  there 
may  have  been  many  spaces  opened  by  tension  between  the  bedding  with- 
out connections  across.  Again,  the  spaces  may  be  simply  the  thin  open- 
ings between  the  laminae  or  leaves  of  a  fine-grained  schist  or  slate,  of 
almost  paper-like  thinness  (Fig.  290),  like  the  spaces  between  the  leaves  in 
a  folded  quire  of  paper,  so  that  the  veins  (which  are  usually  of  quartz)  look 
like  delicate  interlaminations  of  the  slate. 
Moreover,  under  an  oblique  warping  of  the 
beds  by  the  fissure-making  pressure,  vari- 
ous irregularities  are  made  in  the  opened 
spaces. 

The  process  fills  the  opened  spaces,  and 
makes  the  shattered  rock  again  solid,  even 
when  it  is  broken  to  fragments  that  lie 
touching  at  angles  instead  of  being  simply 
fissured.  An  example  (from  Cornwall, 
Eng.)  is  shown  in  Fig.  292,  in  which  gran- 
ite extends  in  veins  into  slate.  Such  cases 
are  common  ;  and  not  unfrequently,  in  the 

same  region  slate  or  schist  occurs  in  masses  inside  the  granite,  as  in  Fig.  495, 
page  448.  The  following  figures  represent  three  parts  of  one  large  gran- 
ite vein,  from  gneiss,  on  the  coast  south  of  Valparaiso,  where  veins  are 

294. 


Granite  veins  in  elate.     De  la  Beche. 


Granite  veins,  Valparaiso.     D.,  '49. 


very  numerous   and  of  all  sizes.     The   figures   show  quite  accurately  the 
bedding  of  the  micaceous  gneiss  along  the  sides  of  different  parts  of  the 


330 


DYNAMICAL   GEOLOGY. 


296. 


vein,  where  the  rock  in  some  places  becomes  a  mica  schist  through  the  in 
crease  in  the  amount  of  mica ;  the  intervals  between  the  sheets  of  granite 
are  all  of  mica  schist  or  gneiss. 

In  the  making  of  fissures,  portions  of  the  walls  have  often  fallen  into 
them.  A  foreign  mass  in  a  vein  is  called  by  miners  a  horse;  while  many 
masses  may  make  it  a  brecciated  vein. 

Veins  are  often  faulted  (Fig.  296).  The  vein  aa'  is  faulted  by  bb',  and 
vein  1  is  in  three  parts  from  other  intersecting  veins.  The  faulting  shows 
that  the  vein  bb'  is  of  later  origin  than 
aa';  but  not  how  much  later,  whether 
one  year  or  a  million.  The  following 
figures  are  from  the  same  region  as 
the  large  granite  veins,  Figs.  293-295. 

In  the  pieces  of  the  vein  in  Fig.  297, 
the  width  varies,  but  this  is  owing  to 
an  oblique  shove  in  connection  with 
the  faulting,  and  to  the  fact  that  the  vein-sheet  varies  in  thickness.  The 
parts  in  Fig.  302  may  have  connection  inside  the  rock,  or  they  may  not. 
In  Fig.  301,  two  parallel  veins,  six  feet  apart,  are  represented  with 
somewhat  similar,  but  still  different,  faulting. 

Veins,  as  well  as  dikes,  derive  part  of  their  irregularities  from  lateral 
displacements  after  the  fracture  is  made.  In  Fig.  303,  a  fissure  is  reduced 


297. 


298. 


299. 


300. 


302. 


Faulted  veins  from  the  vicinity  of  Valparaiso.    D.,  '49. 

to  a  series  of  independent  open  spaces  by  the  downthrow  of  the  side  to  the 
left,  bringing  the  sides  at  intervals  into  contact.  It  may  be  illustrated  in 
a  piece  of  paper  by  cutting  it  across  in  the  direction  of  the  line  a  in  Fig. 
304 ;  then,  after  opening  it  a  little,  and  shoving  one  side  first  to  the  right 
and  then  to  the  left,  the  conditions  in  b  and  c  will  be  obtained.  The  lesson 
taught  is  this :  that  an  interruption  in  a  vein,  or  in  a  trap  ridge,  does  not 
prove  interruption  in  the  original  fracture. 


HEAT  —  VEINS. 


331 


3.  Mineral  Constitution  and  Structure  of  Veins. 

1.  Constitution.  —  Quartz  is  the  most  common  material  of  veins.  This 
is  so  because  siliceous  solutions  form  at  a  low  temperature,  and  easily 
deposit  quartz.  Others  are  feldspathic  and  granitic.  Others  consist  largely 
of  calcite,  barite,  fluorite;  others  of  hornblende,  epidote,  pyroxene,  etc. 
Moreover,  a  large  part  of  the  minerals  of  the  world,  including  most  of  its 
gems  and  ores,  occur  in  veins,  and  some  of  them  only  in  veins.  '  The  min- 
erals are  crystalline  in  texture,  and  where  there  is  any  open  space,  or  seam, 
in  the  course  of  the  vein,  crystals  of  one  or  more  of  the  minerals  line  the 
cavities,  making  geodes.  The  most  magnificent  of  crystallizations  are 
found  in  veins. 


303. 


304. 


When  ores  occur  along  a  vein,  it  is  in  miners'  language  a  lode.  The 
earthy  minerals  of  the  vein  are  the  gangue  of  the  ore,  or  what  goes  with  it, 
and  also  the  veinstones;  and  the  rock  outside  of  the  vein,  the  country  rock. 
Quartz,  calcite,  barite,  and  fluorite,  are  the  most  common  kinds  of  gangue. 

Iron  sulphide,  FeS2,  is  a  very  common  associate  of  all  kinds  of  ores, 
constituting  the  mineral  pyrite  or  marcasite,  generally  the  former.  In  a 
large  part  of  the  important  ores  of  veins,  the  other  metals  are  in  combina- 
tion with  sulphur ;  but  in  many  with  arsenic,  selenium,  tellurium,  bismuth, 
antimony,  with  or  without  sulphur ;  in  a  few  with  chlorine,  iodine,  bromine. 
Some  ores  are  in  the  state  of  carbonates,  sulphates,  phosphates,  arsenates ; 
only  two  of  economical  importance  are  silicates,  and  two  are  oxides.  The 
great  deposits  of  oxides  of  iron  are  in  beds,  and  not  veins. 

A  few  metals  occur  in  the  native,  or  unmineralized,  state,  essentially  pure 
—  as  gold,  platinum,  copper,  silver,  bismuth,  and  sparingly  so  some  others. 
Almost  all  the  gold  and  platinum  of  the  world  is  in  this  condition,  and  a 
large  part  of  the  copper. 

The  upper,  or  exposed,  part  of  a  vein  is  often  a  region  of  much  decom- 
position, because  (1)  ores,  being  mainly  sulphides,  often  oxidize  easily ; 
and  (2)  water  readily  percolates  downward  in  many  veins,  owing  to  the 
nearly  vertical  position  and  structure  of  the  vein,  and  the  frequent  existence 
of  open  spaces  along  the  center  and  sides.  Pyrite  is  often  oxidized  to  red 
ocher,  giving  a  reddish  look  to  the  vein  rock  ;  and  if  it  contains  gold,  it  often 
leaves  the  scales  of  gold  in  the  cavities  it  has  deserted.  Pyrite  also  changes 
to  the  yellow-brown  oxide  of  iron.  Chalcopyrite,  or  sulphide  of  copper  and 


332 


DYNAMICAL   GEOLOGY. 


iron,  also  on  oxidizing  gives  red  or  yellow-brown  colors  to  the  decomposed 
material  of  the  rock.  Moreover,  the  percolating  waters  carry  the  changes 
downward,  and  especially  along  the  sides  and  center  of  the  vein.  The  waters 
descending  along  the  walls  of  the  vein  (and  any  ascending  vapors  also)  often 
alter  the  adjoining  rock  to  clay,  making  along  the  side  walls  the  selvage  of  the 
vein.  Further,  the  waters  may  carry  along  carbonic  acid,  or  sulphuric  acid 
(made  from  oxidized  sulphur),  and  so  convert  oxidized  metals  —  as  of  lead  or 
copper  —  into  carbonate  and  sulphate.  In  this  way  phosphates,  arsenates,  and 
other  salts  of  the  metals,  as  well  as  carbonates  and  sulphates,  become  mixed 
with  the  ores  of  the  vein  as  secondary  products. 

2.  Structure.  —  Fissure  veins  are  either  simple  or  banded.  Those  simple 
in  structure  are  alike  in  mineral  or  minerals  from  side  to  side ;  while  the 
banded  have  the  materials  in  layers  parallel  or  nearly  so  to  the  walls,  so  that 
in  a  cross-section  they  look  banded. 

Granitic  or  feldspathic  veins  are  usually  simple.  They  may  have  great 
width,  extending  sometimes  to  100  feet,  and  may  consist  of  a  number  of 
minerals ;  but  the  minerals  are  not  ordinarily  arranged  parallel  to  the  walls. 
The  larger  veins  sometimes  contain  feldspar  and  quartz  in  crystalline  masses 
that  weigh  tons,  and  mica  in  plates  a  yard  across,  and  occasionally  beryls  as 
large  as  a  flour  barrel.  A  beryl  of  Grafton,  1ST.  H.,  weighed  2900  pounds. 
Some  spodumene  crystals  are  four  feet  long.  From  this  extreme  magnitude 
there  are  gradations  to  those  in  which  the  crystallizations  are  an  inch  and 
less  in  size.  The  granite  of  veins  seldom  has  the  moderate  fineness  and  even- 
ness of  grain  fitting  it  for  architectural  purposes  ;  the  even-grained  kinds  are 
probably  always  of  igneous  origin. 


305. 


306. 


307. 


6  b   43212   4    5  b 

1111 

i  ' 

•  i 

*  ' 

1   i  1! 

• 

'.i 

j 

^  I 

i1  i|  H'I 

I 

BW 

1 

.;!'; 

V 

','1 

f;'| 

if 

ij! 

,'',' 

.'  1  ' 
j  1 

/''ilil 

IS' 

f's 

r'; 

j  1 
ll 

i 

i 

l,'l 

',', 

\V,!| 

i'|i 

1  ', 

i';', 

II 

31 

'; 

I.  ' 

v 

in 

1 

'  !  ;'  V 

Banded  vein,  Valpa- 

raiso.   D. 

^ 


a    T> 


Quartz  vein,  Cheshire, 
Conn.    D. 


Banded  vein,  at  Godolphin  Bridge, 
Cornwall.    De  la  B. 


But  granitic  veins  are  sometimes  banded,  as  in  Fig.  305,  in  which  1,  3, 
and  6  are  bands  of  quartz ;  2  and  4,  bands  having  the  structure  of  gneissoid 
granite,  and  5  that  of  gneiss.  Fig.  306  contains  a  two-banded  vein  of  quartz. 
It  illustrates  the  usual  mode  of  origin  of  bands,  showing  that  they  are  layers 
made  by  deposition  against  the  two  walls.  It  is  also  a  vein  of  copper  ore, 
the  ore  lying  in  the  wider  open  portions  of  the  vein. 

Figs.  307-309  represent  otfyer  banded  veins,  having  the  bands  in  two 


HEAT  —  VEINS. 


383 


or  more  sets.  Fig.  307  appears  as  if  made  up  of  two  veins  side  by  side,  abcb 
one,  and  d  another;  two  bands  b  are  agate  bands  (uncrystallized  quartz),  and 
at  c  are  two  bands  of  crystallized  quartz.  The  two  sides  of  the  fissure  received 
simultaneously  the  deposition  of  agate,  and  then,  over  this,  the  layer  of  quartz 
in  crystals.  If  a  band  or  string  of  ore  had  been  deposited  between  the  two 
of  quartz,  as  is  common,  this  would  have  made  it  an  ore-vein.  But  in  the 

309 


b     b 


d     d 

Compound  veins  from  Cornwall.    De  la  B. 


figure,  the  large  band  d  is  ore,  copper  ore ;  and  to  make  it,  the  fissure  was 
reopened  along  the  wall  to  the  left,  and  the  ore  introduced  without  any 
"  gangue  "  material.  Fig.  308  represents  a  triple  vein,  abba  one,  c  a  second, 
and  dd  the  third ;  and  Fig.  309,  a  sextuple  vein,  or  one  that  was  opened  six 
times  for  new  vein-making.  Each  of  the  six  parts  is  called  a  comb  in 
miners'  language.  In  one  great  vein,  opened  at  Freiburg,  the  layer  consisted 
of  blende  (ZnS),  quartz,  fluorite  (CaF),  pyrite,  galena,  barite,  calcite,  each  two 
or  three  times  repeated,  the  layers  nearly  corresponding  on  either  side  of  the 
middle  seam. 

The  ore  of  veins  occurs  in  one  or  several  of  the  bands ;  or  is  gathered 
along  the  center ;  or  collected  in  the  broader  portions  or  swellings  of  a  vein, 
making  nests ;  or  distributed  through  the  gangue. 

Most  quartz  veins  cutting  through  crystalline  rocks  are  actually  simple, 
though  begun  in  each  case  by  deposition  against  the  walls.  Gold-bearing 
veins  are  commonly  ordinary  quartz  veins,  but  the  gold  is  usually  in 
minute,  invisible  scales  through  the  quartz,  though  occasionally  in  threads 
of  crystals,  and  "nuggets  "  or  larger  masses.  In  the  case  of  the  gold-bearing 
quartz,  crushing,  and  then  either  washing  or  amalgamation,  are  required  to 
obtain  the  gold.  Gold-bearing  quartz  veins  contain  also  more  or  less  pyrite 
in  which  gold  is  often  present  profitably,  and  also  often  galena  (PbS)  and 
sphalerite  or  blende  (ZnS).  A  region  of  chloritic  or  hydromica  schist 
having  interl animating  and  intersecting  veins  of  quartz,  in  which  occur 
some  pyrite  and  galena,  is  almost  always  a  gold  region. 

The  banded  structure  of  many  veins  is  one  of  the  points  in  which  veins 
differ  from  dikes.  But  they  are  often  like  dikes  in  having  contact  minerals 
in  the  walls  of  the  veins,  due  to  the  same  process  which  filled  the  vein. 


334  DYNAMICAL   GEOLOGY. 

4.   Making  of  Veins. 

In  the  making  of  veins,  the  material  has  usually  been  deposited  against 
the  walls ;  and  from  the  wall  layer  thus  made  there  has  been  a  thickening  to 
the  center.  The  work  is,  therefore,  centripetal. 

The  materials  have  been  introduced  either  (1)  from  above,  or  (2)  lat- 
erally, from  the  rocks  adjoining  some  part  of  the  fissure,  or  (3)  from  below. 
The  filling  of  superficial  cracks  is  done  usually  without  aid  from  heat.  But 
in  most  vein-making,  heat  has  been  required. 

1.  Superficial  Vein-making,  not  requiring  Heat.  —  The  shallow  cracks  of 
rocks,  like  those  of  mud-beds,  and  any  cavities  opening  upward,  may  take  in 
calcite,  silica,  or  other  ingredients  from  cold  solutions,  and  make  superficial 
veins.     The  process  is  mere  deposition,  and  commonly  without  heat.     In 
a  similar  manner  cavities  and  caves  have  sometimes  become  filled.      Or 
when  a  bed  is  slightly  calcareous,  permeating  waters  have  taken  into  solu- 
tion some  of  the  calcareous  portion  (calcite),  and  if  cracks  or  fissures  existed, 
have  filled  them  with  calcite.     Siliceous  solutions,  in  like  manner,  may  make 
veins  of  quartz.     So  any  solution  made  by  oxidations  or  other  means,  may 
carry  material  into  cracks  and  produce  veins  or  veinlets. 

2.  Vein-making  requiring  Heat.  —  Vein-making  requiring  heat  is  carried 
on  in  regions  of  hot  springs  in  a  superficial  way.     But  in  general,  the  process 
has  gone  forward  in  fissures  permeating  hot  rocks,  and  the  work  of  filling 
has  been  dependent  on  the  heat  and  moisture  the  rocks  afforded.      These 
fissures,  in  the  case  of  the  majority  of  veins,  have  not  descended  to  regions 
of  fusion ;  while  in  the  case  of  other  veins  of  even  greater  importance,  as 
regards  ore-production,  they  have  reached  fusion-depths  and  have  let  up 
melted  rock.     The  veins  of  the  first  of  these  kinds  are  especially  common 
in  Archaean  rocks ;  while  those  of  the  second  belong  mostly  to  later  time. 

Superficial  Vein-making. 

Superficial  vein-making  is  in  progress  at  hot  springs  in  Nevada,  Cali- 
fornia, and  elsewhere.  Such  springs,  making  solfatara  areas,  are  usually 
in  regions  of  former  eruptions. 

In  Nevada,  at  Steamboat  Springs,  according  to  J.  Arthur  Phillips  (1879), 
fissures  are  being  lined  with  a  siliceous  incrustation,  while  at  the  same  time 
steam  and  gases,  with  boiling  water,  are  escaping;  and  "they  have  been 
subjected  to  a  series  of  repeated  widenings,"  and  become  lined,  to  a  thick- 
ness of  several  feet,  with  silica,  which  is  in  bands,  amorphous  and  crystalline 
alternating,  and  contains  some  hematite,  pyrite,  and  chalcopyrite.  Accord- 
ing to  Mr.  Laur  (1863),  the  silica  of  these  fissures  contains  also  traces  of 
gold ;  so  that  the  facts  exemplify,  as  he  states,  the  essential  points  in  the 
origin  of  auriferous  quartz-veins.  This  view  was  presented  by  B.  Silliman 
and  W.  P.  Blake,  in  1864,  with  reference  to  the  banded  quartz-veins  (gold- 
bearing)  of  Bodie  Mountain,  north  of  Mono  Lake,  which  are  contact  veins 
intersecting  porphyry.  At  Clear  or  Borax  Lake,  as  observed  by  Mr.  Phillips, 


HEAT  —  VEINS.  385 

the  siliceous  deposits  frequently  contain  pyrite  and  cinnabar  (HgS)  and 
the  sulphur  bank,  which  has  there  been  formed  through  the  heated  vapors, 
has  been  worked  as  a  mercury  mine.  J.  D.  Whitney  described  in  1865  a 
specimen  of  gold  in  cinnabar  which  was  supposed  to  have  come  from  near 
"  Sulphur  Springs,"  four  miles  south  of  Bear  Valley,  between  Clear  Lake 
and  Colusa;  and  Mr.  M.  Atwood  removed  doubt  as  to  the  source  of  the 
specimen  by  rinding  in  a  fissure  at  the  place  mentioned  (as  reported  by 
Mr.  Phillips)  cinnabar  overlaid  by  a  brilliant  deposit  of  metallic  gold. 
Similar  facts  are  reported  by  Le  Conte  (1882,  1883),  from  the  Clear  Lake 
region  and  Steamboat  Springs.  In  the  former,  at  "Sulphur  Bank,"  occurs 
sulphur  with  cinnabar  below  (which  is  now  worked),  and  also  pyrite  and 
gelatinous  silica. 

Le  Conte  explains  the  occurrence  of  cinnabar  (HgS)  on  the  ground  of  its  solubility  in 
a  hot  solution  of  sodium  sulphide  (Na.2S),  —  this  alkaline  sulphide  resulting  from  the  action 
of  the  sulphur  gas  on  the  rocks  which  contain  a  soda-lime  feldspar, —  and  its  subsequent 
deposition.  (For  Le  Conte  on  Vein-making,  see  Am.  Jour.  *Sc.,  1882,  1883.)  Becker 
sustains,  by  experiments  (1887),  the  view  that  the  metallic  sulphides  (HgS,  FeS2,  ZnS, 
and  less  easily  Cu2S)  are  soluble  in  solutions  of  alkaline  sulphides,  and  that  they  pass 
in  vapors  to  be  deposited  in  the  veinlets  and  fissures  of  the  rocks  above.  He  observes 
that  the  Steamboat  Springs  are  now  depositing  gold  ;  that  gold  is  dissolved  by  a  hot  solu- 
tion of  Na2S,  and  that  843  parts  of  a  cold  solution  of  Na2S  will  dissolve  one  part  of  gold. 
Deposition  of  the  sulphides  is  occasioned  by  cooling  ;  by  contact  with  acid  waters  —  these, 
according  to  Le  Conte,  descending  from  the  surface  where  some  of  the  sulphur  in  the 
gases  makes  sulphuric  acid  and  aluminum  sulphate  ;  and  also  by  dilution.  Becker  pub- 
lished in  1888  a  full  report  on  the  quicksilver  mines  of  California.  The  following  facts 
illustrate  further  mineral  transformations.  Daubree  found,  in  the  thermal  waters  at  Bour- 
bonne-les-Bains,  in  the  bottom  of  a  part  of  which,  in  Roman  times,  bronze,  silver,  and  gold 
coins  had  become  buried,  the  following  mineral  species,  derived  from  the  alteration  of  the 
metal  of  the  first  two  of  these  kinds  of  coins  through  the  agency  of  the  mineral  waters,  their 
temperature  140°  F. :  the  copper  ores,  chalcocite  (Cu2S),  chalcopyrite  (CuFeS2),  bornite 
(Cu3FeS3),  tetrahedrite,  atacamite,  cuprite  (Cu20),  chrysocolla,  native  copper;  the  lead 
ores,  cerussite  (PbO.CO2),  anglesite  (PbO.SO3),  galena  (PbS),  phosgenite,  and  pyrite. 
The  bronze  was  found  to  consist  of  copper,  tin,  and  lead,  or  of  copper  and  zinc,  with  a 
trace  of  iron.  The  waters  afforded,  on  analysis,  chlorides  and  sulphates  of  the  alkalies 
(Na2,  K2,  Ca,  Mg),  with  bromides  and  carbonates  of  Ca  and  Fe,  an  alkaline  silicate,  with 
traces  of  arsenic,  manganese,  iodine,  boron,  lithium,  strontium,  caesium,  rubidium,  and,  in 
exhalations,  some  H2S,  N,  and  O.  Similar  results  were  observed  by  Daubree  at  the  warm 
springs  of  Plombieres,  Department  of  the  Vosges. 

Veins  made  by  heat  in  the  Earth's  Crust,  without  aid  from  deep-seated  Igneous 

Ejections. 

The  crustal  heat  may  be  that  of  the  earth's  crust  either  during,  or  not 
during,  an  epoch  of  metamorphism.  Under  this  head  are  included  most  of 
the  great  and  small  granite  veins  of  the  world,  the  auriferous  (gold-bearing) 
quartz  veins,  and  all  the  common  veins  of  metamorphic  rocks.  They  some- 
times intersect  the  foliation,  but  very  often  follow  it.  Their  formation  was, 
in  general,  part  of  the  results  of  metamorphic  heat  and  conditions ;  and  the 
movements  attending  mountain -making,  which  produced  the  metamorphic 


336  DYNAMICAL   GEOLOGY. 

heat,  were  the  source  of  the  larger  part  of  the  fissures,  and  the  origin  of 
their  great  diversity  in  form  and  positions.  The  heat  varied,  therefore, 
from  212°  F.  and  below,  to,  in  extreme  cases,  the  temperature  nearly  of 
fusion ;  and  it  slowly  declined  as  the  epoch  of  metamorphism  closed,  thus 
making  the  same  region  to  pass  through  conditions  of  high-grade  heat  and 
low-grade  heat,  and,  therefore,  through  conditions  for  different  sorts  of 
veins.  All  the  transfer  and  transformation  processes  through  superheated 
steam  engaged  in  metamorphism  were  at  work  in  vein-making  with  like 
efficiency  —  those  of  low  heat  for  filling  fissures  with  quartz,  and  those  of 
higher  for  making  feldspathic  or  coarse  granitic  veins,  and  other  kinds. 
Moreover,  the  heat  so  derived  continued  long,  and  disappeared  with  extreme 
slowness ;  so  that  the  filling  of  veins  was  usually  slow,  and  the  crystalliza- 
tions going  on  had  almost  indefinite  time  for  growing,  and  generally  became 
coarse.  The  gigantic  crystals  of  beryl,  mica,  and  other  species  mentioned 
on  page  331  were  thus  made. 

With  the  heat  so  widely  diffused,  it  was  not  necessary  that  the  opened 
spaces  for  veins  should  be  continuous.  An  interrupted  series  of  openings  in 
the  upturned  strata,  as  well  as  the  spaces  between  the  leaves  of  slates  and  the 
thinner  schists,  would  have  become  as  readily  filled  by  materials  supplied  from 
the  rocks,  as  they  would  if  they  had  been  united  along  continuous  fissures. 

The  hot-vapor  solutions,  everywhere  at  work,  would  have  varied  their 
results  according  to  the  temperature,  the  moisture,  and  the  kinds  and  con- 
tents of  adjoining  rocks.  If  the  fissures  penetrated  rocks  having  veins  or 
deposits  of  ore,  or  sparsely  disseminated  ores,  the  ores  would  be  as  readily 
transferred  to  the  veins  as  the  stony  minerals ;  and  the  hot  vapors,  widely 
distributed,  might  gather  them  in  from  a  wide  region  either  side  of  the 
fissure,  whether  at  its  lowest  or  highest  depths.  The  vapors,  being  under  great 
pressure,  would  find  the  fissures  escape-ways,  and  the  transfer  of  material 
would  therefore  begin  as  soon  as  they  were  opened.  Veins  of  lead  ore 
(galena),  copper  ores,  tin  ore,  and  other  kinds  are  common  in  the  same  rocks 
that  elsewhere  have  their  granite  veins.  Moreover,  veins  would  be  likely  to 
contain  ores  at  their  intersections  with  some  of  the  rocks  they  cross  when 
not  at  other  intersections.  As  gold  occurs  commonly  in  quartz  veins,  and  in 
those  of  the  feebly  crystalline  schists,  as  chlorite  schist  and  hydromica  schist, 
no  great  amount  of  heat  was  required  for  their  formation,  and  the  rocks  near 
by  or  below  must  have  afforded  the  gold. 

Igneous  rocks  often  have  fissures  intersecting  them  (due  to  contraction  on 
cooling,  or  to  subterranean  action)  and  cavities  (amygdaloidal)  within  them, 
that  were  filled,  in  vein-like  style,  from  materials  brought  in  laterally,  and 
mostly  while  the  rock  was  slowly  cooling,  as  explained  on  page  298.  The 
permeating  hot  moisture  takes  silica,  alumina,  soda,  and  lime  from  the  feldspar 
of  the  rock,  and  makes  zeolites  (hydrous  silicates,  related  to  the  feldspar)  in 
the  fissures  and  cavities ;  and  takes  silica,  lime,  magnesia,  and  iron  from  the 
pyroxene  to  make,  with  some  alumina,  the  dark  green  chlorite ;  and  sets  free 
the  excess  of  silica  for  making  quartz  crystals. 


HEAT  —  \7EINS. 


337 


The  process  decomposes  the  walls  of  the  fissures  or  cavities  to  make 
the  filling  materials,  the  walls  showing  it  by  their  decayed  condition. 
The  lateral  source  may  be  within  an  inch  or  a  few  inches  of  the  place  of 
deposition ;  and  still  it  well  illustrates  much  of  vein-making.  Bitumen  or 
mineral  oil  may  also  be  taken  in  from  carbonaceous  shales,  and  deposited  in 
the  amygdaloidal  cavities  and  fissures ;  and  to  its  presence  J.  Lawrence 
Smith  attributed  the  reduction  of  the  magnetite  in  igneous  rocks  to 
grains  of  native  iron,  and  even  the  production  of  the  great  masses  of  native 
iron  brought  to  the  surface  by  basaltic  ejections  in  Greenland. 

The  term  vesicle,  as  applied  to  a  vapor-blown  cavity  in  an  igneous  rock, 
has  been  put  into  Greek  form  in  the  word  lithophysa  (stone-bubble)  by 
Kichthofen  (1860),  and  applied  especially  to  peculiar  chambered  cavities 
common  in  obsidian,  its  variety,  lithoidyte,  and  in  rhyolyte.  They  occur 
in  great  perfection,  as  flattened  spheroids,  in  the  region  of  the  Obsidian 
Cliff,  Yellowstone  Park  (Fig.  279,  page  306).  The  following  figures  are  from 


310. 


311. 


313. 


Lithophysae  of  the  Obsidian  Cliff.    Iddings. 

a  memoir  by  J.  P.  Iddings  (1888).     Three  of  the  lithophysas  are  shown, 
of  natural  size,  in  Fig.  310,  and  three  others  in  section  in  Figs.  311,  312,  313. 
The  rock  containing  the  lithophysse  commonly  consists  of  alternating  solid 
DANA'S  MANUAL  —  22 


338  DYNAMICAL   GEOLOGY. 

and  spongy  layers  as  represented  in  Fig.  313,  and  the  thin  harder  bands  in 
this  lamination  or  straticulation  are  persistent  throughout  the  lithophysae ; 
as  the  figure  shows  they  were  sometimes  arched  in  the  making  of  the  cavities, 
while  often,  on  the  other  hand,  they  prevented  the  cavity  from  completing  a 
circular  form.  The  concentric  partitions  are  fragile  and  consist  mostly  of 
minute  crystals  of  quartz,  feldspar,  and  tridymite ;  and  sometimes  topaz  and 
garnets  are  in  the  cavities. 

Richthofen  regarded  the  lithophysse  as  made  by  expanding  steam,  like  vesicles  in 
ordinary  lava,  and  the  concentric  partitions  as  having  been  thrown  off  in  the  progress  of 
the  expansion,  and  hence  the  name.  Mr.  Iddings  points  out  close  relation  between 
the  lithophysse  and  the  associated  radiate  spherulites,  and  doubts  the  vesicular  mode 
of  origin.  The  following  is  a  possible  explanation.  If  the  cavity  made  by  vesiculation 
became  at  first  filled  with  an  aqaeo-igneous  or  jelly-like  solution  of  the  rock,  the  concentric 
shells  may  be  a  centripetal  result,  due  to  progress  in  cooling  and  loss  of  moisture  from  the 
outside.  The  process  would  first  produce  a  deposition  of  crystals  over  the  confines 
or  wall  of  the  cavity,  and  thus  deprive  the  inside  solution,  adjoining  this  wall, 
of  part  of  its  mineral  material ;  then,  the  succession  of  shells  might  form  inside  in  a 
manner  analogous  to  that  given  for  concentric  rings  on  page  130.  Johnston  Lavis  regards 
lithophysse  as  concretions  growing  radiately  outward,  and  refers  the  spaces  between  the 
concentric  shells  to  the  liberation  of  vapor  from  moisture  contained  in  the  glass,  this 
liberation  taking  place  as  the  glass  becomes  changed  to  feldspar  in  solidification.  Whitman 
Cross,  who  adopts  the  vesiculation  theory,  found  beautiful  but  minute  crystals  of  topaz 
and  garnets  in  lithophysse  of  the  rhyolyte,  of  Nathrop,  Col.  (1884,  1886).  Iddings  and 
S.  L.  Penfield  have  described  (1885)  yellow  crystals  of  fayalite  from  those  of  the  black 
obsidian  at  Yellowstone  Park.  Utah  rhyolyte  also  has  afforded  topazes. 

Veins  made  by  the  aid  of  deep-seated  Igneous  Ejections. 

For  the  formation  of  veins  through  the  heat  of  igneous  ejections,  the 
earth's  crustal  heat  has  been  the  agent,  aided  possibly  by  heat  from  local 
crushing  and  friction.  The  fissures  at  great  depths  may  have  had  the  heat 
required,  without  addition  from  mountain-making  movements.  The  general 
steps  of  progress  —  that  is,  the  methods  of  transfer  and  formation  of  mineral 
material  by  heated  vapors  —  are  the  same  that  have  been  described. 

Fissures  descending  to  regions  of  fusion  are  necessarily  deep  fissures, 
and  for  this  reason  the  veins  that  have  been  made  in  connection  with  them 
include  the  richest  of  ore-bearing  veins.  The  deep  fissures  let  out  liquid 
rock.  But  they  were  the  means  of  opening  a  way  for  whatever  vapors  or 
solutions  the  melted  rock  through  its  heat,  supplemented  by  the  earth's 
crustal  heat,  might  gather  from  the  rocks,  or  their  crevices,  along  the  way 
up,  or  from  the  depths  below.  The  copper  veins  of  the  Lake  Superior 
region  are  an  example ;  and  so  are  also  the  richest  and  the  chief  part  of  all 
the  silver,  lead,  and  copper  veins  of  western  America,  from  Fuegia  on  the 
south,  along  the  western  slope  of  the  Andes  to  Central  America,  Mexico, 
Nevada,  Arizona,  Colorado,  Utah,  and  Wyoming. 

The  results  differ  not  only  according  to  the  kinds  of  rocks  below,  but 
also  the  kinds  along  the  upper  part  of  the  fissure :  whether  they  are  (1)  of  dif- 
ficult corrosion,  or  (2)  of  easy  corrosion  like  limestones. 


HEAT  —  VEINS.  339 

1.  The  upper  intersected  rocks  of  difficult  corrosion.  —  These  rocks  are  of 
any  kinds  not  calcareous :  as  shales,  sandstones,  or  other  related  fragmental 
kinds,  or,  but  much  less  frequently,  crystalline  rocks. 

The  famous  copper  mines  south  of  Lake  Superior  are  an  example.  The 
upper  intersected  rocks  are  sandstones,  conglomerates,  and  tufas.  The  igne- 
ous rock  is  mainly  of  the  basaltic  type.  The  copper  is  native  copper  con- 
taining generally  3  per  cent  of  silver,  and  occasionally  speckled  with  silver. 
It  occupies  irregular  fissures  and  cavities  in  the  igneous  rock,  especially  its 
amygdaloidal  varieties,  and  also  occurs  in  the  adjoining  sandstone.  It  some- 
times constitutes  amygdules,  has  often  a  gangue  of  zeolites,  or  coats 
crystals  of  analcite  and  quartz-crystals,  and  thus  it  proves  its  contempora- 
neous origin  with  these  materials.  One  great  sheet  of  copper  was  40  feet 
long,  6  feet  wide,  and  6  inches  thick,  and  weighed,  by  estimate,  200  tons.  The 
conditions  show  that  the  copper  came  up  along  with  abundant  moisture  from 
some  deep-seated  source.  In  1891,  the  mining  at  the  Calumet  and  Hecla 
mine  had  gone  down  4000  feet.  It  is  probable  that  the  deep-seated  source 
was  a  region  of  veins  in  Archaean  rocks  along  the  line  of  the  fissure  or 
fissures  holding  chalcopyrite,  the  most  common  of  copper  ores. 

Another  example  is  that  of  the  remarkable  Comstock  lode,  Nevada,  along 
a  faulted  fissure  —  now  a  deserted  mining  region.  The  igneous  rock  at  the 
broad  vein  is  of  the  basaltic  type,  and  intersects  a  region  of  andesyte  of 
Tertiary  age.  The  ore  deposit  extends  along  the  contact  of  the  igneous  rock 
with  those  it  intersects.  The  gangue  is  mainly  quartz.  The  ore  is  largely 
silver  sulphides  with  some  native  silver  and  native  gold,  the  last  nearly  half 
the  value  of  the  products.  Hot  vapors  ascend  the  opening,  and  during  the 
working  it  made  the  cooling  of  the  air  with  ice  necessary  in  order  to  reach 
the  lower  depths ;  and  finally  the  heat  caused  the  desertion  of  the  mine.  By 
means  of  the  vapors,  the  diabase  and  other  adjoining  rocks  had  become 
deeply  decomposed  to  clay.  The  total  yield  up  to  July,  1880,  was  over  306 
millions  of  dollars.  (King,  1870;  Becker,  1882  ;  Hague  and  Iddings,  1885.) 

In  other  related  veins,  the  rocks  cut  through  by  the  upper  part  of  the 
fissure  vary  in  porosity  and  in  other  ways  ;  and  some  of  the  beds  become 
impregnated  with  ores,  while  others  receive  little  or  none.  Such  impregna- 
tions are  occasionally  found  where  no  igneous  rock  by  which  they  could 
have  been  produced  is  in  sight.  The  following  sections,  illustrating  a  case 


314.  315. 


of  this  kind,  are  from  a  report  made  in  1879,  by  Kothwell  and  Crouch,  on  a 
district  on  Virgin  River,  in  Utah,  250  miles  south  of  Salt  Lake.  The 
formation  containing  the  ore-beds  (o)  is  probably  Cretaceous  (see  Gilbert's 


340  DYNAMICAL   GEOLOGY. 

Hep.,  158,  171,  1875).  The  ore  is  chiefly  silver  chloride  or  horn-silver.  The 
rocks  are  sandstone,  argillaceous  sandstone,  and  shale.  The  ore-beds  are 
usually  clayey  layers  or  shales,  and  the  ore  is  most  abundant  when  the 
clays  contain  vegetable  remains.  Eruptive  rocks  are  not  far  away,  and  J.  E. 
Clayton,  in  the  same  report,  urges  that  hot  vapors,  derived  either  from  the 
fissures  of  eruption,  or  from  other  wide-spread  fracturings  made  by  the  erup- 
tive movements,  were  the  chief  source  of  the  distributed  ores. 

In  southern  Utah  and  in  Colorado,  according  to  J.  S.  Newberry,  veins  exist  made  of 
coarse  gravel  and  stones,  in  which  the  stones  have  become  coated  with  argentiferous  galena 
and  other  ores,  including  silver  chloride,  that  were  received  from  below.  They  are  worked 
for  the  silver.  Examples  are  the  Bassick  and  Bull  Domingo  mines  near  Silver  Cliff,  Col., 
and  the  Carbonate  mine  at  Frisco,  Utah.  The  large  fissures  were  opened  near  the  base  of 
the  mountains,  where  they  became  filled  with  the  pebbles,  stones,  and  bowlders  of  all  kinds 
there  accumulated,  and  yet  received  the  ascending  metallic  solutions,  and  also  siliceous 
solutions,  which  deposited  at  the  Bassick  mine  much  chalcedony  among  the  stones. 

2.  The  intersected  rocks  of  easy  corrosion.  —  Many  of  the  richest  ore- 
deposits  of  the  world  occupy  cavities  in  limestone  made  by  the  corroding 
action  of  solutions  or  vapors.  The  cavities  were  eroded  usually  along  joints 
or  fractures  of  the  limestone.  Examples  occur  in  the  Leadville  region,  Col- 
orado ;  in  the  Wasatch  and  Oquirrh  mountains,  Utah ;  at  the  Eureka  mine, 
Nevada ;  in  Lake  Valley,  New  Mexico  ;  in  the  Los  Carlos  Mountains,  Mexico ; 
and  elsewhere.  The  ores  of  these  mines,  as  generally  of  others,  are  of  two 
classes  :  (1)  the  original,  and  (2)  the  secondary  —  mainly  the  latter.  The 
original  ores  include  galena  (PbS),  containing  some  silver  and  chalcopyrite, 
with  sometimes  pyrite  and  sphalerite  (ZnS).  Some  of  the  secondary  are 
silver  chloride  and  bromo-chloride,  made  from  the  silver  of  the  galena; 
lead  sulphate,  carbonate,  phosphate  (and  less  commonly  vanadate  and  mo- 
lybdate),  made  from  the  galena;  zinc  silicate,  made  from  sphalerite;  and 
also  iron  oxide  (hematite  or  limonite),  made  from  pyrite  and  from  iron  in 
the  limestone ;  and  manganese  oxides,  probably  from  the  limestones. 

The  following  figures  show  the  forms,  at  Leadville,  of  some  of  the  cavities 
of  ore  in  the  corroded  limestone  (a  blue  Carboniferous  limestone)  underneath 
a  sheet  of  porphyry,  the  latter  being  the  igneous  rock  which  carried  up  with 
it  the  ore  and  heated  vapors.  They  are  from  the  very  valuable  Report  of 
S.  F.  Emmons  (1886).  The  porphyry  is  also  usually  altered  and  often  pene- 
trated for  some  distance  with  ore,  and  its  decomposition  has  afforded  part  of 
the  ore  for  the  limestone  cavities.  Although  the  ore  deposits  are  usually  in 
a  Carboniferous  limestone  at  Leadville,  the  time  of  the  outflow  of  the  por- 
phyry and  of  the  making  of  the  cavities  was  not  earlier  than  the  Cretaceous 
period  (Emmons).  The  similar  silver-lead  mines  of  all  western  America  are 
probably  likewise  Cretaceous  (chiefly  the  Laramie  or  later  Cretaceous),  or 
else  Tertiary. 

At  the  famous  Eureka  Mine,  eastern  Nevada,  where  the  rocks  are  all 
Paleozoic,  the  eruptions  were  Tertiary,  according  to  Hague  (1892),  and 
mostly  late  Tertiary ;  they  were  partly  along  old  fault-planes  of  post-Carbonif- 


HEAT  —  VEINS. 


341 


erous  age,  and  partly  through  new  fissures.  The  ores  occur  along  the  dikes, 
and  also  penetrate  the  limestones ;  the  ejection  of  the  igneous  rocks,  andesyte 
and  rhyolyte,  was  accompanied  by  the  upward  passage  of  the  ores ;  and  the 
ores  became  much  changed  to  secondary  kinds  by  the  action  of  the  vapors. 
The  latest  eruptions  of  the  region  were  of  basalt. 


316. 


317. 


White  Porphyry 


Gray  Porphyry 


Blue  Limestone 


Vein-    Ore 
material 


Fig.  316,  two  Carbonate  Hill  sections,  Leadville,  showing  cavities  of  ore  in  the  inclined  stratum  of 
limestone,  a,  limestone;  6,  porphyry;  c,  ore.  Fig.  317,  section  at  Printer  Boy  Hill  mine;  letters  same 
signification.  Emmons. 

The  abundance  of  chloride  and  bromide  of  silver  in  these  western  mines 
makes  it  probable  that  sea  water  contributed  to  the  ascending  vapors, 
and  that  salt  (NaCl)  supplied  the  chlorine.  .In  the  Cretaceous  period,  the 
mountain  region  was  mostly  submerged.  The  ores  are  supposed  to  have 
come  from  the  igneous  rocks.  (Becker,  Emmons.)  This  was  probably  true 
to  a  large  extent  in  some  cases,  according  to  the  facts  afforded  by  the  Kewee- 
naw  copper  region.  The  hot  lavas  carried  much  of  the  metallic  material  to 
the  surface,  and  as  cooling  commenced,  the  ores  were  condensed  in,  or  gath- 


342  DYNAMICAL   GEOLOGY. 

ered  into  fissures,  and  amygdaloidal  and  other  cavities  disseminated  through 
the  amygdaloidal  rock ;  and  under  such  conditions  they  have  been  mined  in. 
the  Keweenaw  copper  region  to  the  great  depth  mentioned. 

At  Leadville,  and  other  like  regions,  the  liquid  lavas  were  in  part  the 
carriers  of  the  ores  and  vapors  to  the  surface ;  but  the  chief  part  of  the 
concentration  of  the  ores  and  the  corrosion  of  the  limestone  may  have  taken 
place  during  the  cooling  of  the  lavas.  The  solid  rocks  of  the  globe  take  in 
their  small  percentage  of  moisture  from  the  waters  that  become  subterranean, 
and  then  hold  it ;  a  flow  of  such  waters  downward  through  such  rocks,  and  a 
draining  out  of  their  ores,  cannot  take  place,  except  as  complete  decomposi- 
tion is  produced ;  and  the  small  depth  to  which  decomposition  extends  in 
most  igneous  rocks  shows  that  the  process  is  extremely  slow.  The  processes 
of  decomposition  and  concentration  were  long  kept  in  progress  by  the  vapors 
that  continued  to  rise  from  below  after  the  eruption  had  ceased.  Finally, 
the  infiltration  into  the  vein,  or  vein-masses,  of  cold  waters  from  above  has 
carried  on  further  the  work  of  alteration  and  corrosion,  and  this  work  is  still 
in  progress. 

3.  Ore  deposits  of  doubtful  origin  occurring  in  limestone.  —  Great  lead 
deposits  occur  in  Paleozoic  limestones  of  the  Mississippi  Valley  in  Wis- 
consin, northern  Illinois,  and  Iowa,  and  in  Missouri  and  bordering  parts 
of  Kansas  and  Arkansas.  They  occupy  cavities  or  caverns  in  various  lime- 
stones from  the  Cambrian  to  the  Subcarboniferous.  The  mines  of  Wisconsin 
and  Illinois  are  in  the  Galena  limestone  (or  the  upper  part  of  the  Trenton 
limestone)  of  the  Lower  Silurian;  those  of  southeastern  Missouri,  in  the 
Third  Magnesiaii  limestone,  of  Cambrian  age ;  those  of  southwestern  Mis- 
souri, in  the  Keokuk  limestone  of  the  Subcarboniferous  period,  and  to  a 
small  extent  in  the  Cambrian ;  those  of  central  Missouri,  chiefly  in  the 
Cambrian  limestone,  but  partly  in  the  Subcarboniferous  limestone. 

The  lead  ore,  galena,  is  associated  with  pyrite,  marcasite  ;  the  zinc  ores, 
calamine  (zinc  silicate)  and  smithsonite  (zinc  carbonate);  lead  carbonate, 
malachite,  barite,  and  in  some  places  with  black  cobalt  and  an  ore  of  nickel. 

The  ore,  in  each  of  the  regions  mentioned,  occurs  in  cavities  or  caverns 
in  the  different  limestones.  From  the  resemblance  between  the  various 
deposits,  it  is  concluded  that  the  time  of  origin  was  the  same  for  all,  and 
not  earlier  than  the  Subcarboniferous  period,  the  age  of  the  latest  of  the 
limestones. 

As  first  made  known  in  the  geological  report  of  Wisconsin  by  J.  G. 
Percival  (1858),  the  ore-bearing  cavities  follow  the  courses  of  the  joints  (or 
system  of  fractures)  in  the  limestone,  and  are  most  extensive  along  the 
larger  joints,  which  are  sometimes  the  lines  also  of  faults.  This  fact  has 
been  confirmed  by  later  observations. 

In  the  Transactions  of  the  St.  Louis  Academy  of  Science  for  1875,  A. 
Schmidt  announced  the  conclusion  that  the  ore-containing  cavities  in  the 
Missouri  limestones  were  made  when  the  alterations  of  the  galena  took 
place,  producing  the  associated  minerals,  and  principally  in  the  more  porous 


HEAT  —  VEINS.  343 

part  of  the  limestone  stratum  where  limited  above  and  below  by  cherty 
layers ;  that  the  rock  adjoining  was  largely  converted  into  dolomite  by  mag- 
nesian  solutions,  and  that  this  "  dolomization "  was  an  early  step  in  the 
process,  and  aided  in  making  the  cavities ;  that  the  ores  often  occur  mixed 
up  with  chert  or  sand  that  were  set  loose  by  the  decomposition  of  the  lime- 
stone. 

There  are  two  theories  of  origin,  one  deriving  the  ore  from  above,  the 
other  from  below.  The  former  is  favored  and  the  latter  opposed  by  the 
absence  of  proof  that  the  bodies  of  ore  extend  downward  through  the  lime- 
stone vein-like,  and  that  igneous  action  was  concerned.  The  theory  of  filling 
from  above  encounters  the  objections  that  the  ores  of  lead  are  not  soluble, 
and  could  not  have  been  carried  into  the  cavities  in  solution  by  sea  water, 
and  that  the  gathering  of  galena  from  Archaean  veins,  once  in  .the  regions, 
by  abrading  and  transporting  waters,  is  improbable,  and  does  not  account  for 
the  presence  of  the  eroding  agents  which  made  the  cavities. 

The  other  theory,  which  was  suggested  by  Percival,  and  is  advocated  by 
Jenney  (1893),  makes  the  deposits  similar  in  origin  to  the  silver-lead  deposits 
of  Leadville  and  other  Kocky  Mountain  localities.  But  the  objections  to  it 
mentioned  above  exist;  and  so  they  do  in  the  case  of  some  Colorado  ore 
deposits,  where  igneous  action  below  is  nevertheless  believed  to  be  probable. 
The  making  of  the  ore  deposits  is  generally  referred  to  the  close  of  Paleozoic 
time,  when  the  Appalachians  were  made ;  but  Jenney  supposes  it  to  have 
been  at  the  close  of  the  Cretaceous  period,  simultaneous  with  that  of  most 
Colorado  deposits. 

In  Derbyshire,  England,  the  Subcarboniferous  limestones  contain  similar 
lead  deposits,  and  along  with  the  ores  are  Permian  fossils,  proving  that 
they  originated  not  earlier  than  the  Permian. 


The  different  modes  of  origin  of  ore-bearing  deposits,  above  described,  are  the 
following.  In  the  deeper  veins  the  earth's  interior  heat  has  been  accessory  to  special 
sources  of  heat. 

A.    HEAT  FROM  CRUSTAL  MOVEMENTS,  AND  NOT  FROM  IGNEOUS  EJECTIONS  OR 

HOT  SPRINGS. 

(1)  Regular  veins.  — Mostly  in  metamorphic  rocks. 

(2)  Grouped  interlaminar  veins.  —  Generally  short,  as  the  smaller  auriferous  quartz 
veins  of  gold  regions,  and  some  tin,  copper  and  other  veins. 

B.   HEAT  FROM  IGNEOUS  EJECTIONS,  VAPORS,  AND  HOT  SPRINGS. 

(3)  Ore  impregnating  non-calcareous  rocks. 

(4)  Veins  or  groups  of  veins  intersecting  non -calcareous  rocks. 

(5)  The  ores  in  veins  intersecting  calcareous  rocks,  and  occupying  cavities  in  them 
made  by  their  corrosion.     Often  combined  in  the  same  region  with  3. 

Besides  these  there  are,  of  uncertain  origin  :  — 

(6)  Cavities  supposed  to  be  in  part  previously  made  limestone  caverns,  as  those  of  the 
Mississippi  Valley. 


344 


DYNAMICAL   GEOLOGY. 


The  principal  kinds  of  ore  deposits  that  have  no  relation  to  veins  are  as  follows :  — 
(1)  Beds  of  iron  ore  called  lirnonite,  including  marsh-made  ores  (page  128),  sometimes 
containing  also  manganese  oxide,  cobalt  oxide,  and  some  black  copper  oxide ;  (2)  beds 
consisting  of  concretionary  masses  of  clay  iron-stone,  the  ore  either  hematite,  limonite,  or 
siderite,  —  common  in  coal  regions  ;  (3)  beds  of  hematite  and  magnetite  in  inetamorphic 
and  other  rocks,  which  often  stand  vertical  and  look  like  veins,  whence  they  are  sometimes 
so  called  ;  (4)  auriferous  gravel  deposits  along  valleys,  made  by  the  degradation  of  schists 
that  are  intersected  by  veins  of  auriferous  quartz. 

* 

4.  Sediment-filled  fissures.  —  Fissures  have  sometimes  become  filled  with 
sand  or  gravel  from  the  adjoining  beds.  Near  Astoria,  Oregon,  occur  several 
large  sandstone  veins  of  this  kind.  One  of  them,  half  a  mile  above  that 
place  (Fig.  318),  is  five  feet  wide,  and  extends  the  whole  height  of  the  bluff; 
it  has  two  transverse  faults,  the  upper  one  eight  feet.  The  filling  is  granitic 
sandstone,  like  that  of  the  inclosing  rock.  Another,  18  inches  wide,  is 
shown  in  Fig.  319;  it  is  in  the  same  rock  two  and  one  half  miles  above 

320. 


318. 


319. 


Figs.  318,  319,  sandstone  veins,  near  Astoria,  Oregon.     D.,  1849.    Fig.  320,  sandstone  veins,  south  of  Shasta 

Peak.     Diller,  1890. 

Astoria.  Fig.  320  represents  similar  sandstone  veins  from  the  coast  region 
in  California,  south  of  Mount  Shasta,  described  by  J.  S.  Diller  (1890).  Diller 
infers,  from  his  observation,  that  the  fissures  were  filled  from  below  by 
upthrust  force  during  the  progress  of  an  earthquake. 


HYPOGEIC    WORK.  345 

VI.   EARTH-SHAPING,  MOUNTAIN-MAKING,  AND   THE  ATTENDANT 
PHENOMENA:    HYPOGEIC   WORK. 

The  preceding  chapters  on  the  origin  of  geological  phenomena  treat  of 
the  agencies  by  which  rocks  were  made,  denuded,  crystallized,  and  filled 
with  veins  and  ores.  The  subject  of  the  present  chapter  is  the  nature  and 
origin  of  the  changes  through  which  the  earth  has  received  its  form  and 
features,  hypogeic  work,  of  which  the  erogenic  part  is  the  most  noticeable. 
It  does  not  comprise  the  work  of  waters  in  giving  mountain-like  shapes 
to  plateaus,  and  thus  producing  mountains  of  circumdenudation,  or  in  making, 
by  accumulation,  hills  of  detritus ;  nor  the  work  of  heat  in  building  up  vol- 
canic cones,  the  earth's  mountains  of  igneous  accumulation,  or  in  making 
laccolithic  domes  or  masses  (laccoliths)  —  mountains  of  subterranean  igneous 
accumulation;  for  these  operations  have  already  been  considered;  but  work 
that  is  consequent,  whatever  its  source,  on  crustal  and  interior  movements 
in  the  earth,  as  expressed  in  the  term  HYPOGEIC,  from  the  Greek  VTTO,  beneath, 
and  yfj,  the  earth.  The  attendant  phenomena  comprise  fractures  of  the  earth's 
crust  and  supercrust,  dislocations,  flexures,  crystallization  and  alteration  of 
rocks,  rock-melting,  and  other  effects. 

The  facts  and  explanations  here  presented  are  supplemented  in  the  fol- 
lowing pages  on  Historical  Geology,  and  the  chapter  will  be  best  under- 
stood if  those  pages  have  already  been  made  familiar. 

ACTUALITY  OF  CHANGES  OF  LEVEL. 

All  geological  history  testifies  against  the  stability  of  the  rocky  crust  of 
the  globe ;  and  if  the  earth,  as  is  believed,  has  cooled  from  fusion,  abundant 
reason  for  this  unstableness  exists ;  for  the  effects  of  the  earth's  slowly  pro- 
gressing refrigeration  reach  backward  indefinitely,  and  downward  beneath 
all  other  agencies  of  change. 

But  the  evidence  of  instability,  although  the  fact  is  so  obvious,  is  beset 
with  doubts  as  to  amount  and  position,  because  of  possible  and  actual  varia- 
tions in  the  base  from  which  measurements  are  -naturally  made.  This  base 
is  the  water-line  about  the  land.  Hence,  we  have  to  consider  the  sources  of 
variation  in  sea  level. 

1.  Changes  in  the  level  of  the  sea-bottom.  —  When  water-made  strata  full 
of  marine  fossils  are  found  at  a  height  of  1000  feet  above  the  sea,  the 
evidence  of  a  rise  of  at  least  1000  feet  appears  to  be  plain.  Yet,  a  lowering 
of  the  sea-bottom  might  produce  the  same  result ;  and  it  may,  therefore,  be 
a  question  whether  in  such  a  case  part,  or  all,  of  the  apparent  upward  change 
has  not  been  so  produced. 

So,  also,  by  a  reverse  movement  in  the  sea-bottom,  an  apparent  subsidence 
might  result.  Here  there  is  actual  change  of  level,  but  it  may  be  thousands 
of  miles  away  from  the  land  along  which  the  change  is  made  visible.  Change 
so  caused  will  affect  all  seacoasts  alike;  and  in  this  fact  a  criterion  exists  for 
judging  of  its  reality. 


346  DYNAMICAL   GEOLOGY. 

2.  Changes  in  the  position  of  the  earth's  axis.  —  If  a  change  should  take 
place  in  the  position  of  the  earth's  axis,  through  changes  of  level  in  the  earth's 
crust,  the  coast-lines  of  the  earth  would  be  throughout  affected  by  the  new 
adjustment  of  the  water  level.     Physicists  have  very  nearly  relieved  geology 
of  this  source  of  doubt,  by  the  decision  that  an  effective  change  of  this  kind 
is  exceedingly  improbable  (page  255). 

3.  A  change  in  the  level  of  the  land.  —  By  the  law  of  gravitation,  elevated 
lands  attract,  and  thus  draw  the  mobile  waters  of  the  ocean  toward  them 
to  a  height  dependent  on  their  mass  and  distance.     Consequently  the  sea- 
margin  of  all  coasts  is  more  or  less  displaced,  and  much  so,  wherever  the 
land  mass  adjoining  rises  high  above  it.     It  has  been  calculated  that  from 
this  cause  the  sea  level  at  the  center  of  the  Eurasian  continental  mass  is 
about  2900  feet  above  the  sea  at  its  margin  (R.  S.  Woodward)  ;  at  the  center 
of  the  Australian  mass,  about  400  feet  (G.  G.  Stokes,  1849,  1887) ;  of  the 
great  plateau  of  India,  1000  feet,  but  under  the  volcanic  mountain  of  Maui, 
Haleakala,  10°  in  mean  slope,  only  10  feet. 

The  facts  make  it  evident  that  the  water-line  along  nearly  all  coasts,  and 
especially  on  the  west  coast  of  North  and  South  America,  must  be  very 
largely  moved  inland  by  the  mountain  chains ;  and  that,  through  geological 
time,  changing  levels  have  always  been  changing  the  water-lines.  It  is  to  be 
observed,  furthermore,  that  this  inland  drawing  of  the  ocean's  water  dimin- 
ishes the  height  of  the  mountains  above  the  sea.  The  error  is  on  the  side  of 
too  little  height. 

The  piling  of  ice  over  the  land  in  a  glacier  epoch  has  a  like  effect,  but 
with  material  having  about  two  fifths  the  gravity  of  the  ordinary  land 
material.  Were  the  ice  of  a  glacial  epoch  to  be  accumulated  about  the 
poles,  and  thus  make  a  polar  ice-cap  or  meniscus  thousands  of  feet  high, 
the  ocean  level  would  be  changed  through  all  latitudes  to  the  equator.  This 
cause  has  been  thought  sufficient  to  explain  apparent  subsidences  in  the 
hemisphere  so  capped. 

But  since  the  change  of  water  level  from  the  equator  to  the  pole  would 
follow  a  geometric  ratio,  admitting  of  mathematical  calculation,  the  accord- 
ance of  the  theory  with  actual  facts  is  easily  tested.  In  eastern  America 
the  subsidences  closing  the  Glacial  period  supposed  to  be  thus  accounted 
for  by  Croll  have  no  correspondence  with  the  required  heights.  Moreover, 
observations  have  proved  that  there  was  no  such  polar  ice-cap  in  the  Glacial 
period. 

4.  Abstraction  of  water  from  the  ocean.  —  Further,  the  making  of  great 
continental  accumulations  of  ice  would  lower  the  level  of  the  ocean  and  tend 
to  raise  the  apparent  level  of  the  land. 

With  the  above  cautionary  considerations  in  view,  noting  that  the  obser- 
vations about  ice  relate  only  to  glaciated  regions,  that  the  error  from  the 
attraction  of  the  land  is  on  the  side  of  too  little  height,  and  that  sea-bottom 
changes  of  level  affect  all  coast-lines  alike,  the  following  facts  may  be  ac- 
cepted as  proof  of  changing  levels  over  the  earth's  surface. 


HYPOGEIC  WORK.  347 

EXAMPLES  OF  CHANGES  OP  LEVEL  IN  THE  LAND. 

1.  Movements,  up  or  down,  are  now  going  on  along  the  coast  of  North 
America,  Scandinavia,  Greenland,  and  elsewhere.     Alexander  Agassiz  states 
that  at  Tilibiche,  in  Peru,  there  is  a  coral  limestone,  2000  to  3000  feet  above 
the  sea  level,  extending  along  for  20  miles,  in  which  occur  corals  modern  in 
aspect ;  and  that  the  existence,  in  Lake  Titicaca,  of  eight  species  of  a  salt- 
water genus  of  Crustaceans,  Allorchestes,  suggests  the  presence  of  the  sea 
over  this  region,  12,500  feet  in  height,  at  no  very  distant  period.     There  is 
no  proof  of  corresponding  changes  over  eastern  South  America. 

2.  On  the  coast  of  Cuba,  limestone    strata,    made   in   the  sea  off  the 
shores,  are  now  (according  to  W.  0.  Crosby)  at  different  levels  up  to  a 
height  of  1800  feet,  and  near  Havana,  over  1200  feet ;  and  on  Jamaica  (ac- 
cording to  Mr.  Sawkins),  and  Haiti  (according  to  W.  P.  Blake),  of  2000  feet. 

3.  In  the  early  Tertiary,  the  European  and  Asiatic  seas  contained  Num- 
mulites,  and  limestones  were  made  of  the  multiplying  disks.     Now,  those 
Eocene  Nummulitic  beds  are  at  a  height  of  9000  feet  in  the  Pyrenees,  11,300 
feet  in  the  Alps,  16,500  feet  in  the  Himalayas  in  western  Tibet,  and  a  few 
hundreds  only  near  Paris. 

4.  In  the  Cretaceous  period,  the  region  of  a  large  part  of  the  Rocky 
Mountains  and  of  the  Atlantic,  Gulf,  and  Pacific  borders  of  the  continent 
were  beneath  the  sea,  but  mostly  near  its  surface ;  and  the  marine  life  of 
the  sea  contributed  to  the  forming  of  Cretaceous  beds.     Now,  the  marine 
beds,  filled  with  Cretaceous  fossils,  are  at  a  height  of  10,000  to  11,000  feet  in 
the  Rocky  Mountain  region ;  at  a  maximum  height,  on  the  Pacific  border,  of 
only  5000  feet ;  in  Alabama  of  700  to  800  feet ;  and  in  New  Jersey  not  over 
400 ;  and  in  portions  of  the  western  mountain  regions  the  beds  are  in  great 
flexures. 

5.  In  the  Appalachian  region,  from  the  site  of   Albany,  N.Y.,  to  Ala- 
bama, at  or  near  the  end  of  the  Carboniferous  period,  the  surface  was  near 
the  sea  level,  and  the  rocks,  from  the  Cambrian  to  the  Carboniferous,  lay  in 
a  horizontal  pile,  the  upper  surface  little  emerged  above  sea  level.     Now, 
they  are  in  mountain  flexures,  and  heights  of  several  thousand  feet  occur 
along  the  line. 

6.  All   the   world's   mountains,  excepting  those   of  igneous  formation, 
consist  of  rocks  that  were  made  chiefly  in  the  sea ;  and  the  highest  of  them 
reached  their  present  level  during  the  latest  of  the  geological  ages.     And 
while  some  portions  of  the  earth's  surface  were  raised  in  later  geological 
time  10,000  to  19,000  feet,  other  parts  underwent  little  or  no  recognizable 
elevation. 

7.  Formations  of  all  thicknesses  to  tens  of  thousands  of  feet  bear  evi- 
dence of  the  shallow-water  origin  of  the  successive  beds ;  and  they  thus 
prove  that,  while  forming,  a  subsidence  of  extreme  slowness  was  in  progress 
over  the  great  area;  slow  enough  for  the  accumulation  of  the  material  in 
the  surface  waters  by  living  growth  if  the  beds  consist  of  limestone,  and  by 


348  DYNAMICAL   GEOLOGY. 

water-action,  if  of  sedimentary  origin.  The  shallow-water  origin  of  beds  is 
so  generally  true  that  thick  formations  in  almost  all  cases  are  proof  that  a 
slow  subsidence,  equal  in  amount  to  the  thickness,  was  going  on  over  the 
area  during  the  deposition ;  and  also  that  without  such  a  subsidence  the 
making  of  thick  strata  or  formations  has  rarely  taken  place. 

Such  evidences  of  actual  change  of  level  are  good,  and  have  profound 
significance.  Geology  has  thus  proved  that :  — 

1.  Unequal  changes  have  been  in  progress  simultaneously  in  different 
parts  of  the  same  continent. 

2.  The  changes  in  level  have  usually  gone  forward  with  extreme  slow- 
ness—  by  the  few  inches   or  feet  a  century,  though  sometimes   also  by 
abrupt  displacements.     The  former  are  termed  secular  changes,  the  latter 
paroxysmal. 

Another  class  of  facts  is  represented  by  the  following  from  Illinois  :  — 
A  section  of  the  coal  formation  of  Illinois,  described  by  Worthen,  con- 
tains 16  coal-beds,  large  and  small,  separated  by  fragmental  beds  and  lime- 
stones containing  abundant  remains  of  marine  life.  The  coal-beds  indicate 
eras  of  emerged  land,  the  marine  fossils,  intervening  eras  of  submergence,  and 
their  number  shows  that  at  least  sixteen  alternations  between  the  two  con- 
ditions there  took  place  in  the  Carboniferous  period.  Facts  make  it  certain 
that  the  great  Interior  Sea  of  the  continent  communicated  at  that  time  freely 
with  the  ocean  to  the  south.  The  same  region  thus  went  up  and  down, 
changing  the  dry  land  outline  and  the  sea  depths ;  and  the  changes  went  on 
with  extreme  slowness,  for  coal-beds,  as  well  as  the  much  thicker  marine 
beds,  were  slow  in  accumulation.  Facts  of  similar  import  are  afforded  by 
all  the  successive  formations,  from  the  Cambrian  upward,  and  alike  on  all 
the  continents.  In  explanation  of  such  changes  it  may  be  questioned 
whether  subsidences  over  the  sea-bottom  may  not  have  produced  some  or 
all  of  these  oscillations  in  level.  As  far  as  evidence  can  be  obtained,  the 
changes  were  independent  of  movements  in  the  ocean ;  for  the  coal-beds  of 
Illinois  and  those  of  Ohio  and  Pennsylvania  do  not  show  that  uniformity 
of  parallelism  which  this  hypothesis  requires. 

Further :  changes  of  level  are  now  in  progress,  both  of  the  slow  secular  kind 
and  of  the  sudden  or  paroxysmal.  The  following  sketch  represents  a  case  in 
which  a  Roman  temple  has  passed  through  a  time  of  partial  submergence 
below  the  level  of  the  Mediterranean.  The  temple  is  that  of  Jupiter  Serapis 
at  Pozzuoli.  It  was  originally  134  feet  long  by  115  wide ;  and  the  roof  was 
supported  by  46  columns,  each  42  feet  high,  and  five  feet  in  diameter.  Three 
of  the  columns  are  now  standing,  and  they  bear  evidence  of  submergence  for 
a  considerable  time  to  half  their  height.  The  lower  twelve  feet  are  smooth ; 
for  nine  feet  above  this,  they  are  penetrated  by  lithodomous  or  stone-boring 
shells,  remains  of  which  (a  species  now  living  in  the  Mediterranean)  were 
found  in  the  holes.  The  columns,  when  submerged,  were  consequently  buried 
in  the  mud  of  the  bottom  for  12  feet,  and  were  then  surrounded  by  water  nine 
feet  deep.  The  pavement  of  the  temple  is  now  under  water.  Five  feet  below 


HYPOGEIC    WORK. 


349 


321. 


it,  there  is  a  second  pavement,  proving  that  these  oscillations  had  gone  on 
before  the  temple  was  deserted  by  the  Romans.  It  has  been  stated  that, 
for  some  time  previous  to  1845,  a  slow  sinking  had  been  going  on,  and  that 
since  then  there  has  been  as  gradual  a  rising. 

At  the  earthquake  in  1819,  about  the  delta  of  the  Indus,  an  area  of  2000 
square  miles  became  an  inland  sea ;  and  the  fort  and  village  of  Sindree  sunk 
till  the  tops  of  the  houses  were  just  above  the  water.  Five  and  a  half  miles 
from  Sindree,  parallel 
with  this  sunken  area, 
a  region  50  miles  long 
and  in  some  parts  10 
broad  was  elevated  10 
feet  above  the  delta. 
The  natives  call  it,  with 
reference  to  its  origin, 
Ullah  Bund,  or  Mound 
of  God.  In  1838,  the 
fort  of  Sindree  was  still 
half  buried  in  the  sea; 
and,  during  an  earth- 
quake in  1845,  the  Sin- 
dree Lake  was  turned 
into  a  salt  marsh. 

In  1822,  the  coast 
along  by  Concepcion 
and  Valparaiso,  for  1200 
miles,  was  shaken  by  an 
earthquake;  and  it  has 
been  estimated  that  the 
coast  at  Valparaiso  was 
raised  three  or  four  feet. 
In  February,  1835,  an- 
other earthquake  was 
felt  from  Copiapo  in 
Chile,  eastward  beyond 
the  Andes  to  Mendoza. 
Captain  Fitzroy  states  that  there  was  an  elevation  of  four  or  five  feet  at 
Talcahuano,  which  was  reduced  by  April  to  two  or  three  feet.  The  south 
side  of  the  island  of  Santa  Maria,  near  by,  was  raised  eight  feet,  and  the 
north,  ten  feet ;  and  beds  of  dead  mussels  were  found  on  the  rocks,  ten  feet 
above  high-water  mark. 

The  secular  movements  which  have  been  observed  are  confined  to  the 
middle  and  higher  temperate  latitudes,  and  may  be  a  continuation  of  the 
series  which  characterized  the  earlier  part  of  the  Quaternary  age. 

In  Greenland  a  slow  subsidence  is  taking  place.     For  600  miles  from 


Temple  of  Jupiter  Serapis. 


350  DYNAMICAL   GEOLOGY. 

Disco  Bay,  near  69°  1ST.,  to  the  Firth  of  Igaliko,  60°  43',  the  coast  has  been 
sinking  for  four  centuries  past.  Old  buildings  and  islands  have  been  sub- 
merged; and  the  inhabitants  have  had  to  put  down  new  poles  for  their 
boats,  the  old  ones  standing,  Lyell  observes,  "as  silent  witnesses  of  the 
change." 

On  the  North  American  coast,  south  of  Greenland,  from  Labrador  to 
New  Jersey,  it  is  supposed  that  similar  changes  are  going  on.  G.  H.  Cook 
concludes,  from  his  observations,  that  a  slow  subsidence  is  in  progress- 
along  the  coasts  of  New  Jersey,  Long  Island,  and  Martha's  Vineyard,  and 
has  deduced,  from  the  positions  of  buried  stumps  over  large  areas  along 
the  New  Jersey  coast,  a  rate  of  two  feet  a  century.  According  to  A.  Gesner 
the  land  is  rising  at  St.  John,  in  New  Brunswick ;  sinking  at  the  island  of 
Grand  Manan ;  rising  on  the  coast  opposite,  at  Bathurst ;  sinking  about  the 
head  of  the  Bay  of  Fundy,  where  there  are  regions  of  stumps  submerged 
35  feet  at  high  tide,  and  about  Minas  Basin,  in  Nova  Scotia,  except,  perhaps, 
on  the  south  side. 

On  page  149  the  reasons  are  given  for  believing  that  coral  reefs  and 
islands  are  proof  of  a  slowly  progressing  subsidence,  as  first  suggested  by 
Darwin.  On  the  physiographic  chart,  page  47,  the  line  CCC,  extending  in  an 
easterly  direction  from  the  Pelews,  divides  coral  islands  from  those  not  coral. 
Over  the  area  north  of  it,  to  the  Hawaiian  Islands,  all  the  islands  are  atolls, 
excepting  the  Marquesas  and  three  or  four  of  the  Carolines.  If,  then,  the 
atolls  are  registers  of  subsidence,  a  vast  area  has  partaken  in  it,  —  meas- 
uring 6000  miles  in  length  (a  fourth  of  the  earth's  circumference),  and 
1000  to  2000  in  breadth.  Just  south  of  the  line  there  are  extensive 
coral  reefs;  north  of  it  the  atolls  are  large,  but  they  diminish  toward 
the  equator,  and  mostly  disappear  north  of  it;  and,  as  the  smaller  atolls 
indicate  the  greater  amount  of  subsidence,  and  the  absence  of  islands 
still  more,  the  line  AA  may  be  regarded  as  the  axial  line  of  this  great 
Pacific  subsidence.  The  amount  of  this  subsidence  may  be  inferred,  from 
the  soundings  near  some  of  the  islands,  to  be  at  least  3000  feet.  But  as 
200  islands  have  disappeared,  and  it  is  probable  that  some  among  them  were 
at  least  as  high  as  the  average  of  existing  high  islands,  the  subsidence  in 
some  parts  cannot  be  less  than  5000  feet.  This  sinking  probably  began  in 
the  Tertiary  era. 

During  the  progress  of  this  subsidence,  or  since  it  ceased,  there  have  been 
many  cases  of  isolated  elevation.  The  following  are  some  examples  from 
the  Pacific:  Oahu  (Hawaiian  Islands),  25  feet;  Elizabeth  Island,  Paurnotu 
Archipelago,  80  feet ;  Metia  or  Aurora,  250  feet ;  Atiu,  Hervey  Group,  12 
feet ;  Mangaia,  300  feet ;  Rurutu,  150  feet ;  Eua,  Tonga  Group,  nearly  500 
feet;  Vavau,  500  feet;  Savage  Island,  100  feet;  Eota  and  Guam,  of  the 
Ladrones,  600  feet.  More  than  25  others  have  undergone  some  elevation. 
Off  the  New  Guinea  coast,  some  atolls  have  been  raised  to  a  height  of  300 
or  400  feet,  and  a  central  basin  100  feet  deep,  with  vertical  walls  around, 
occupies  the  place  of  the  old  lagoon. 


HYPOGEIC   WORK.  351 

Thus  the  earth  is  still  undergoing  changes  from  paroxysmal  movements 
and  prolonged  oscillations.  The  changes,  while  probably  more  restricted 
than  in  the  ages  of  progress,  are  yet  the  same  in  kind. 


CHARACTERISTICS  OF  DISTURBED  REGIONS  AND  MOUNTAINS. 

General  Explanations. 

1.  The  general  range  of  effects.  —  A  disturbance,  in  geological  usage,  is  an 
event  in  which  rocks  —  formations  of  wide  extent  —  are  moved,  and  more  or 
less  fractured  in  the  process.     Over  some  great  areas  they  have  been  shoved 
up  or  depressed  with  little  variation  from  horizontality  ;  and  over  others 
there  have  been  profound  flexures  and  faults  involving  thousands  of  feet 
of  strata  throughout  regions  hundreds  of  miles  wide  and  thousands  long. 
Explanations  and  illustrations  have  already  been  given  of  upturned  beds, 
flexures,  faults,  and  flexure-faults    (page  99),  and  of  the  metamorphism 
and  vein-making,  which  have  attended  great  mountain-making  movements. 
The  object  of  the  present  chapter  isvto  present  all  the  various  orographic 
phenomena   in   their   relations   as   they   occur   combined  in   the  structure 
of  mountain  ranges  and  systems  of  ranges,  and  to  explain,  so  far  as  is  at 
present  possible,  the  origin  of  orographic  movements  and  of  the  resulting 
structures. 

In  the  first  place,  some  facts  in- molecular  physics  of  fundamental  impor- 
tance as  regards  flexures,  fractures,  and  faultings  of  solids,  are  here  briefly 
illustrated,  and  then  follow  descriptive  examples  of  several  mountain-struct- 
ures, as  a  prelude  to  the  discussion  of  the  question  of  origin. 

2.  The  flow  of  solids.  —  Solid  metal  and  rock,  when  under  pressure,  as 
first  illustrated  by  Tresca,  yield  through  molecular  movement,  and  may  thus 
become  compressed,  drawn  out,  flexed,  and  otherwise  deformed.     The  yield- 
ing is  very  much  like  that  in  a  bent  bag  of  shot,  through  movements  in 
the  shot.     In  the  case  of  metals,  ice,  and  rocks  of  even  texture,  the  change, 
if  slow  enough,  may  take  place   without  fractures.     In  the  bending  of  a 
mass  of  rock  or  ice  by  gravity,  molecules  of  one  side  push  the  adjoining, 
and  these  others  throughout   the  mass,  until  the   adjustment  is  complete. 
Hence  the  density  is  nowhere   changed.     The  flow  of  metals  is  now  util- 
ized extensively  in  the   shaping  and  punching  of  cold  metal  for  various 
purposes  in  the  arts.     In  experiments  at  the  Stevens  Institute,  Hoboken, 
by    Mr.    David   Townsend    (Journal   of   the   Franklin   Institute   for   March, 
1878),  rectangular  blocks  of  iron,  accurately  planed  and  measured   (being 
made  about  1-75  inches  wide  and  thick,  and  2-5  inches  long),  were  punched 
cold  through  the  center  with  a  punch  T7g    of  an    inch   in   diameter.     The 
core  which  came  out  (Fig.   323)   was  only  J-i  of  an  inch  (instead  of  1-75 
inches  =  -f f )  long ;  and  yet,  like  the  punched  block,  it  was  essentially  un- 
changed in  density.     Mr.  Townsend's  experiments  and  measurements  show 
that  six  tenths  of  the  metal  which  had  filled  the  hole  had  moved  off  lat- 


352 


DYNAMICAL   GEOLOGY. 


erally,  or  in  the  direction  of  the  width  and  length  of  the  block ;  and  this 
lateral  movement  or  flow  had  bulged  the  sides  much  more  at  bottom  than 

at  top,  and  most  about  the  middle.     At 

322v  bottom  the  block  was  increased  -^  in 

width  and  -£-$  in  length.  The  block  had 
been  made  of  plates  of  iron  welded  to- 
gether, and  these  were  bent  downward 
as  the  punch  passed  in,  the  lower  ones 
the  least;  and  Fig.  322  shows  the  ap- 
pearance of  the  surface,  after  polishing 
and  etching  with  acids,  of  a  section 
through  the  middle,  when  the  punch 
had  entered  1J  inches,  and  the  core  pro- 
jected an  eighth  of  an  inch. 

Such  facts,  together  with  those  re- 
lating to  the  heat  developed  by  friction, 
take  the  mystery  out  of  the  process  of 
flexing  rocks. 

3  Fractures  and  displacements  under 
pressure.  —  The  production  of  fractures 
through  lateral  pressure  has  been  experi- 
mentally illustrated  by  Daubree.  In  one 
of  his  experiments  he  used  an  oblong 
square  prism  consisting  of  layers  of 
Core  out.  Townsend.  beeswax,  and  applied  the  force  at  the 

middle  of  the  two  ends  after  protecting 

them  by  small  blocks  or  plates  of  the  same  cross-section.  Fig.  324  repre- 
sents, half  the  natural  size,  the  prism  ready  for  the  experiment.  One  of 
the  results,  after  applying  the  pressure,  is  shown  in  Fig.  325  ;  and  another, 
after  using  a  stronger  pressure,  in  Fig.  326. 

In  both,  a  flexure  becomes  the  course  of  a  fracture,  and  also  of  a  fault ; 
and  in  326  it  is  shown  that  the  flexure-fault  is  not  at  the  axis  of  the  flexure, 
but  beyond  it,  between  the  anticline  and  syncline.  In  Fig.  327  are  shown 

324. 


Punch  at  a  depth  of  1£  inches. 
323. 


Prism  made  of  layers  of  wax  of  different  colors,     (x  3.)     Daubree. 

two  oblique  fractures  and  faults,  obtained  in  another  trial.  The  fractures 
have  their  planes  parallel  as  well  as  very  oblique ;  and  the  faults  were  made 
by  a  shove  up  along  the  oblique  surface.  So  the  greater  fractures  of 
mountain  regions  usually  have  like  obliquity  as  well  as  parallelism,  and 


HYPOGEIC    WORK.  353 

sometimes  large  displacements  in  the  same  upthrust  way.     The  direction  of 
dip  of  the  plane  of  fracture,  as  the  figures  show,  is,  in  the  case  of  a  synclinal 

325.  326. 


bend,  the  reverse  of  that  in  the  anticlinal. 

In  subjecting  to  vertical  pressure  a  square  block  of 

wax,  having  a  breadth  of  five  and  a  half  inches  and  a 

height  of  about  a  foot,  an  oblique  diagonal  fracture  was  made  with  some 

bulging  of  the  sides ;  and,  adjoining  the 
fracture,  as  a  consequence  of  the  molecular 
movements  in  the  bulging,  fine  rectangular 
cracks  were  produced,  like  a  delicate  net- 
work. 

Cubes  of  hard  rock  under  vertical  press- 
ure usually  break  off  at  the  angles  and 
edges,  leaving  two  rounded  cones  with  their 

apexes  at  the  middle ;  but  a  tabular  block  of  limestone  was  reduced  by  Daubre"e 

to  vertical  prisms  and  plates.  ' 

CHARACTERISTICS  OF  SOME  TYPICAL  MOUNTAIN  RANGES. 
1.    The  Appalachian  Mountain  Range. 

The  structure  of  the  Appalachian  Mountains  was  first  investigated  by 
Professors  W.  B.  and  H.  D.  Kogers  in  connection  with  geological  surveys 
of  the  States  of  Virginia  and  Pennsylvania;  and  their  results  (1842) 
gave  many  fundamental  principles  to  orographic  science. 

Fig.  328,  A,  B,  sections  of  part  of  the  belt  in  Virginia,  by  H.  D.  Campbell, 
afford  a  general  idea  of  the  system  of  flexures  (1893).  Each  represents  the 
rocks  for  a  breadth  of  about  10  miles  across  the  range,  in  Eockbridge  and 
Bath  counties.  Between  the  two  sections  there  is  an  interval  of  about  eight 
miles.  The  numbering  of  the  formations  corresponds  with  that  on  page  410 ; 
the  limestone  areas  are  blocked,  the  shales  ruled,  and  the  sandstones  dotted. 
Farther  to  the  southeast,  in  the  same  line,  there  are  closely  crowded  over- 
thrust  flexures. 

In  the  construction  of  the  mountain  range  from  New  York  to  Alabama 

(1)  the  whole  Paleozoic  series  of  strata  to  the  floor  of  crystalline  Archaean 

rocks  —  in  some  parts  40,000  feet  thick  —  were  involved  in  the  system  of 

flexures ;  (2)  the  flexures  are  generally  parallel  to  the  axis  of  the  mountain 

DANA'S  MANUAL  —  23 


354  DYNAMICAL   GEOLOGY. 

range ;  (3)  the  axis  is  usually  nearly  straight,  but  sometimes  bends  around 
through  a  large  arc;  (4)  instead  of  one  flexure  for  the  range,  or  parallel 
flexures  of  like  length,  there  is  generally  a  succession  along  the  mountain 
region,  one  rising  near  where  another  ends,  making  overlapping  series. 
There  is  no  crumpling  of  the  beds,  and  no  long  intervals  of  horizontal  beds 
alternating  with  the  flexed.  Some  single  flexures  are  80  to  100  miles  long ; 
and  they  vary  in  span  from  one  mile  or  so  to  20  or  more.  In  the  finer  kinds 
of  rocks  flexures  occur  of  a  few  inches  or  less,  which  are  like  wrinkles  on 
the  great  rock-sheets. 

(5)  The  flexures  have  rarely  the  ridge  line  horizontal;  and,  in  adjoin- 
ing flexures  it  often  inclines  in  opposite  directions,  this  being  a  mechanical 
effect  in  the  process  of  warping. 

Further  (6),  the  axial  plane  of  a  flexure  is  seldom  vertical,  the  opposite 
slopes,  in  a  transverse  section,  being  unlike ;  hence  the  flexures  are  mostly 
unsymmetrical,  even  when  not  overthrust  flexures  (page  103).  Again  (7),  the 
flexures  have  the  steeper  side  generally  facing  northwest,  away  from  the  Atlan- 
tic Ocean;  at  the  same  time  they  are  by  far  the  most  numerous  and  close- 
pressed,  and  most  generally  overthrust,  in  the  eastern  part  of  the  range,  or 
the  side  toward  the  ocean.  The  mountains  have  consequently  a  front-and-rear 
structure,  the  front  side  facing  the  ocean. 

This  flexing  of  rocks  to  such  depths  appears  less  incredible  when  it  is 
noted  (a)  that  the  strata  so  treated  were  generally  those  of  sedimentary 
formations ;  (6)  that  they  were,  for  the  most  part,  only  partially  consoli- 
dated, the  limestones  excepted;  (c)  that  all  the  rocks  contained  much 
moisture,  and  had  their  cohesion  diminished  thereby ;  (d}  that  as  the  move- 
ment proceeded,  heat  was  being  generated  by  friction,  which,  if  low  in 
degree,  made  siliceous  solutions  that  would  diminish  friction  by  the  dissolv- 
ing action,  and,  if  high,  produced  superheated  vapor  and  a  general  softening 
of  the  flexing  masses. 

Again  (8),  great  upthrust  faults,  with  displacements  10,000  to  20,000 
feet  or  more,  exist  in  the  region  of  flexed  rocks,  and  especially  where  the 
flexures  are  overthrust  and  close  pressed ;  and  they  are  sometimes,  if  not 
generally,  flexure-faults,  with  the  thrust  westward  along  the  flank  plane  of 
the  overthrust  flexure.  Professors  W.  B.  and  H.  D.  Rogers,  in  their  ad- 
mirable paper  on  the  Appalachians,  observe  that  "  the  passage  of  an  inverted 
fold  into  a  fault  is  of  common  occurrence,"  and  that  some  flexure-faults 
have,  "in  southwestern  Virginia,  a  length  of  about  100  miles."  They 
always  occur  on  the  northwest  side  of  the  flexure,  as  in  the  following 
figures  taken  from  two  of  their  sections  ;  and  they  begin,  say  these  authors, 
with  the  thinning,  or  "disappearance  of  one  or  more  of  the  groups  of 
softened  strata  lying  immediately  to  the  northwest  of  the  more  massive 
beds."  "  The  dislocation  increases  as  it  is  followed  along,  until  finally  the 
lower  beds  (II)  of  the  Lower  Silurian  are  found  resting  directly  on  rocks 
of  the  Carboniferous  series  (X,  XI)."  These  two  sections  are  from  the 
same  fault,  the  first  near  its  place  of  beginning,  and  the  second,  where  the 


HYPOGEIC   WOBK. 
328. 


355 


IBack  Creek 


//'  Mill  Mountain 


Back  Creek  Mountain 


-CoM.Sulphur  Springs 


Waif  Pasture  River 


&? 


The  Knob 


•  Jackson  River 


^-Little  Calf  Pasture  River 


*Warm  Springs 


W.arm  Springs  Mtn. 


Little  North  Mtn. 


Jump  Mountain 


ill 


Littl.e  Piney  Mtn. 


Little  Mare  Mta. 


356 


DYNAMICAL   GEOLOGY. 


condition  is  nearly  that  just  stated,  the  lower  beds  (II)  being  in  contact 
with  the  Devonian  (VIII).  In  the  former,  III  and  V  (Hudson  Eiver  and 
Clinton  shales),  of  the  flank  of  the  anticline,  are  greatly  thinned  down  (as 
compared  with  the  thickness  on  the  other  side  of  the  flexure).  To  the 
southwest  the  strata  successively  disappear  until  the  condition  in  Fig.  330 

329. 


III  IV       V       VII      V     IV     III         11 


exists ;  and  then  that  in  which  II  and  XI,  both  great  limestones,  are  in  con- 
tact. But,  as  they  state,  the  ingulfed  strata  may,  in  some  places  along  the 
course,  be  found  standing  in  isolated  knobs  between  the  two  formations, 
II  and  XI.  The  Professors  Rogers  observed,  as  reported  by  Lesley,  that  the 
lines  of  faults  of  Virginia  are  continuous  with  flexures  in  Pennsylvania. 

Just  beyond  the  cluster  of  great  faults  in  the  Appalachians  comes  the 
high  plateau,  or  table-land,  characteristic  of  the  northwest  border  of  the 
Appalachian  Range.  In  East  Tennessee  it  is  called  the  Cumberland  Table- 
land; Fig.  331,  by  Safford,  represents  it  with  the  height  proportionally 

331. 


N.  w. 


.S.  E. 


Cumberland  Table-land,  Tennessee;  c,  Crab  Orchard  Mountain;  2,  Cambrian;  3,  4,  Lower  Silurian 
(Calciferous  and  Trenton);  5,  Upper  Silurian;  7,  Devonian  (Black  shale);  8,  Subcarboniferous;  9,  Coal 
measures.  Vertical  scale  2000  feet  =  1  inch ;  horizontal,  12  milea  =  1  inch. 

much  exaggerated.  It  is  2000  feet  high,  and  900  to  1200  above  the  Great 
Valley  of  East  Tennessee  (the  low  eastern  part  in  the  figure),  which  is  the 
region  of  the  great  flexures  and  faults  reduced  to  a  valley  by  denudation. 


HYPOGEIC   WORK.  357 

The  width  is  40  miles  for  the  higher  part,  and  25  to  30  for  the  lower 
western  portion.  Farther  west  is  the  central  basin  of  Tennessee,  a  region 
of  Lower  Silurian  rocks.  Tennessee  thus  owes  its  grander  features,  its  high 
eastern  table-land,  and  its  transverse  plain  beyond  at  a  lower  level,  to  move- 
ments attending  the  making  of  the  Appalachian  Mountains,  and  the  denuda- 
tion which  ensued. 

The  Cumberland  Table-land  is  continued  northeastward  through  Virginia 
and  Pennsylvania  to  southern  New  York  and  the  Catskills ;  and  in  this 
northern  part  it  is  over  4000  feet  high,  and  fronts  the  Hudson  River  Valley 
with  precipices  of  nearly  2000  feet.  The  Great  Valley  of  East  Tennessee 
becomes,  as  the  Professors  Eogers  observed,  the  Shenandoah  Valley  in  Vir- 
ginia, the  Cumberland  Valley  in  Pennsylvania,  the  Kittatinny  of  New  Jersey, 
and  the  Newburg  part  of  the  Hudson  River  Valley  in  New  York. 

This  prolongation  of  prominent  features,  orographic  and  denudational, 
gives  an  individual  character  to  the  Appalachian  Range.  Lesley's  colored 
geological  map  of  Pennsylvania,  the  first  in  his  geological  atlas  of  counties, 
illustrates  well  the  interlocking  flexures  in  the  rocks  as  they  pass  through 
the  state,  with  the  great  table-land  region  on  the  west  and  north.  The  facts 
are  displayed  also  on  his  topographical  map  of  the  state,  a  reduced  copy  of 
which  is  introduced  on  page  730. 

(9)  The  making  of  the  Appalachian  Mountains  went  forward  after  the 
close  of  the  Carbonic  era,  and  hence  the  mountains  stand  as  a  fitting  time- 
boundary  to  Paleozoic  history.  (10)  During  all  Paleozoic  time,  the  pre- 
paratory work  of  making  the  rocks  was  slow  in  progress.  Moreover,  the 
deposition  of  the  30,000  to  40,000  feet  of  strata  took  place  within  a  gradu- 
ally deepening  trough,  or  geosyncline,  the  deepening  so  gradual  that  the 
deposition  kept  pace  with  it.  The  great  trough  had  an  area  as  long  and 
wide  as  that  of  the  future  mountain  range.  The  Paleozoic  strata  in  it  have 
consequently  a  thickness  20,000  to  25,000  feet  greater  than  the  same  series  of 
strata  in  Indiana  and  Illinois  —  regions  outside  of  the  geosyncline.  This 
depth  is  made  certain  by  the  fact  that  the  Carboniferous  marshes  nowhere 
lay  much  above  the  sea  level  when  the  Paleozoic  series  was  completing. 

(11)  Facts  indicate  that  the  trough  had  some  subordinate  longitudinal 
flexures  along  its  bottom;  but  still,  as  the  diminution  westward  in  the  thick- 
ness of  the  beds  shows,  it  was  one  trough. 

The  knowledge  of  the  Appalachian  facts  led  Professor  James  Hall  to  sug- 
gest in  1859  that  a  similar  trough  of  deposition  preceded  the  upturning  in  all 
cases  of  mountain-making.  It  was  the  first  statement  of  this  grand  prin- 
ciple in  orography. 

2.   The  Post-Triassic  or  Palisade  System  of  Ranges  in  Eastern  North  America. 

The  Palisade  mountain  system  comprises  eight  to  ten  independent  ranges. 
They  occur  at  intervals  over  a  region  1000  miles  long,  extending  from 
Nova  Scotia  and  Prince  Edward  Island  on  the  north,  southwestward  to  the 


358  DYNAMICAL   GEOLOGY. 

northern  limit  of  South  Carolina.  The  ranges  are  from  10  miles  in  length 
to  about  350  miles  ;  and  their  general  course  is  closely  parallel  to  that  of  the 
Appalachian  Mountains,  even  to  its  westward  bend  in  Pennsylvania.  They 
overlie  Archaean  or  Cambro-Silurian  rocks.  The  Connecticut  River  Range  is 
120  miles  long ;  and  the  "  Palisade  Range,"  extending  from  southern  New 
York,  on  the  Hudson,  into  Virginia,  is  350  miles  long.  See,  further,  the 
account  of  the  American  Triassic  under  Historical  Geology.  The  rocks 
are  solely  Triassic  in  age.  The  depth  of  the  rocks  of  the  ranges  varies 
from  3000  to  possibly  8000  feet.  Facts  prove  that  they  were  laid  down  in. 
each  case  in  an  independent,  gradually  deepening  geosyncline. 

The  strata,  through  the  whole  1000  miles,  are  alike  in  their  essentially 
fresh-water  or  brackish-water  formation  ;  in  the  granitoid  origin  of  the  sand- 
stones and  shales,  as  well  as  in  their  general  system  of  structure. 

The  dip  of  the  beds  is,  with  rare  exceptions,  monoclinal,  and  mostly 
between  5°  and  25°  in  angle.  In  the  Connecticut  Valley,  it  is  5°  to  25° 
eastward.  In  the  Palisade  belt,  about  the  same  westward.  In  two  North 
Carolina  belts,  the  eastern  has  eastward  dip,  and  the  western,  westward. 
Flexures  are  local,  and  of  rare  occurrence.  The  only  marked  one  that  has 
been  reported  is  a  large  syncline  in  the  short  Richmond  basin. 

The  rocks  are  much  faulted.  But  this  is  not  evident  in  large  visible 
displacements  along  fractures,  but  in  the  striated  or  scratched  surfaces  over 
large  areas,  which  indicate  the  slipping  of  bed  on  bed,  and  along  the  surfaces 
of  the  numerous  small  fractures ;  sometimes  all  sides  of  blocks,  even  when 
they  are  no  larger  than  the  hand,  are  striated. 

All  the  Triassic  areas  have  their  lines  of  trap-dikes ;  and  the  associa- 
tion of  the  igneous  rocks  with  the  stratified  is  so  intimate  and  so  extended 
that  the  two  must  have  had  in  some  way  a  common  history.  The  ejection  of 
some  of  the  trap,  moreover,  preceded  the  later  depositions  of  sandstone.  The 
trap-ridges,  which  consist  of  a  large  trap-mass,  generally  200  to  300  feet 
thick,  underlaid,  and  partly  overlaid,  by  sandstone,  have  usually  a  bold 
palisade-like  front  (page  804),  of  which  the  "Palisades"  on  the  Hudson  are 
an  example,  and  the  name  Palisade  System  is,  therefore,  an  appropriate 
name  for  the  system  of  ranges. 

The  facts  indicate  (1)  a  general  unanimity  of  movement  in  a  series  of 
geosynclines  or  troughs  that  were  wholly  separated  from  one  another  in 
fcheir  rock-making ;  and  (2)  a  disturbance  that  resulted  almost  everywhere 
in  monoclinal  uplifts  of  low  angle,  and  was  accompanied  in  most  parts,  now 
and  then,  or  at  the  close,  with  fissure-ejections.  There  is  hence  a  combina- 
tion in  the  Palisade  System  of  eight  or  ten  individual  mountain  ranges.  In 
the  nearly  total  absence  of  flexures,  the  ranges  differ  from  the  Appalachian 
Range,  while  like  it  in  the  preparatory  geosyncline  of  deposition  and  in  the 
occurrence  of  great  faults. 

The  Sierra  Nevada  Range  is  supposed  to  have  been  made  at  the  close  of 
the  Jurassic,  or  a  period  later. 


HYPOGEIC    WORK. 


359 


3.  The  Laramide  Mountain  System,  including  the  Wasatch  Range. 

The  Laramide  system  of  mountain  ranges  extends  along  the  summit  of  the 
Rocky  Mountains  far  northward  into  British  America,  and  southward  into 
Mexico.  In  British  America,  just  north  of  Montana,  the  upturned  belt  lies  east 
of  the  Archaean  protaxis.  In  the  United  States  it  occupies  the  summit  region 
of  the  mountains,  between  the  line  of  the  Wasatch  Archaean  and  the  Front 
Range  or  protaxis.  Dr.  G.  M.  Dawson  states  that,  in  British  America,  the 
belt  of  upturned  rocks  along  the  summit  of  the  Rocky  Mountains  extends 
from  Montana  northwestward,  with  a  small  interruption,  to  the  Arctic  Ocean, 
which  it  reaches  west  of  the  Mackenzie  delta. 

The  rocks  involved  were  those  of  all  Paleozoic  and  Mesozoic  time,  Cam- 
brian beds  making  the  bottom,  and  the  Laramie,  or  the  uppermost  forma- 
tion of  the  Cretaceous,  the  top.  The  whole  thickness  of  the  series  in 
British  America,  between  50°  and  54°  K,  is  34,000  feet  (R.  G.  V.  McConnell, 
1887),  and  in  the  region  of  the  Wasatch,  about  31,000  feet  (C.  King,  1878)  ; 
as  nearly  as  has  been  learned  this  was  the  final  depth  of  the  geosyncline  in 
which  the  deposits  were  accumulated. 

The  facts  from  British  America,  as  reported  by  McConnell  (1887)  and 
Dawson  (  1886),  are  much  like  those  of  the  Appalachian  region. 

The  following  figures,  by  McConnell,  from  a  point  in  the  range  not  far 
from  the  line  of  the  Canadian  Pacific  Railway,  show  the  Cretaceous  rocks 

332 


333 


Cr 


(Cr,  Cr)  overlaid  by  the  Cambrian  (C),  or  the  bottom  beds  of  the  Paleozoic, 
almost  horizontally  for  a  width  of  two  miles ;  and  the  describer  states  that 
the  whole  width  of  the  overthrust  of  the  Cambrian  at  this  place  is,  by  his 
estimate,  seven  miles.  These  Cambrian  beds  are  overlaid  on  the  west  by 
Devonian  beds  (D),  and  by  the  Carboniferous  (Cbf,  Cb'),  which  have  a  fault 
(F)  between  them.  The  thrust  is  away  from  the  ocean,  as  in  the  Appa- 


360 


DYNAMICAL   GEOLOGY. 


lachian  region  of  east  Tennessee ;  and  other  flexures  in  this  part  of  the  region 
are  overthrust  in  the  same  way.  In  the  western  half  of  the  disturbed  belt 
Silurian  and  Devonian  strata  occur,  and  there  is  one  fault  in  which  the 
thrust  is  westward.  Similar  facts  and  sections  are  reported  by  Dawson  from 
the  country  just  south,  between  the  parallels  of  51°  and  49°. 

335. 


Map  of  the  Wasatch  Mountains  and  adjoining  part  of  Utah.     Reduced  from  the  large  colored  plate  of  the 

Atlas  of  the  Fortieth  Parallel  Survey. 

To  the  south  of  this  region,  in  western  Wyoming,  according  to  A.  C. 
Peale  (1877)   and  0.  St.  John   (1878),  there  are  sections  similar  to  those 


HYPOGEIC   WORK.  361 

described  by  McConnell  and  Dawson.  Farther  south,  in  Utah,  stands  the 
Wasatch  Range  of  the  same  Laramide  system.  The  accompanying  map  of 
the  Wasatch  is  a  reduction  of  the  colored  geological  map  in  the  Atlas  of  the 
Eeport  of  the  Fortieth  Parallel  Survey  under  Clarence  King,  and  the 
highly  instructive  facts  here  presented  are  from  King's  volume. 

The  Wasatch  Mountains  extend  for  more  than  a  hundred  miles  along  the 
east  side  of  the  Great  Salt  Lake  Valley.  They  face  west  with  a  bold  front, 
rising  abruptly  from  the  plain  to  a  height  of  5000  to  6000  feet,  which  is 
10,000  to  12,000  feet  above  tide  level.  At  the  western  foot  are  Ogden,  Uinta, 
Salt  Lake  City,  and  Provo.  The  eastern  slopes  are  more  gradual.  East  of 
its  southern  half  stretch  away  the  Uinta  Mountains  for  150  miles,  a  great 
east-west  plateau,  or  table-land,  feebly  anticlinal  in  structure,  and  10,000  to 
over  13,000  feet  high.  Only  one  fourth  of  its  length  is  within  the  limits  of 
the  map.  North  of  the  Uinta  Mountains  there  is  the  great  "Wasatch 
Eocene  basin,"  lettered  W  on  the  map,  5000  to  7000  feet  above  the  sea  level, 
and  south  of  it  the  "  Uinta  Eocene  basin,"  nearly  10,000  feet  high,  let- 
tered U. 

One  remarkable  feature  of  the  Wasatch  Eange  is  its  backbone  of  Ar- 
chaean rocks  along  its  western  front,  —  a  mountain  range  of  Archaean  origin 
which  stood  there,  submerged  or  emerged,  through  all  the  rock-making  and 
mountain-making  of  Paleozoic  and  Mesozoic  time,  the  prototype  and  model- 
ler of  the  later  Wasatch  Mountains.  There  are  four  Archaean  areas  in  sight 
along  the  range,  indicated  on  the  map  by  the  Nos.  1  to  4,  and  by  a  covering 
of  small  v's. 

Commencing  at  the  north,  Nos.  1  and  2  are  short,  but  No.  3  has  a  length  of  25  miles. 
Between  No.  3  and  No.  4,  and  nearly  abreast  of  the  Salt  Lake  City  site,  comes  the  great 
gap  of  15  miles  in  the  Archaean.  South  of  the  gap,  No.  4  has  a  height  of  11,295  feet, 
but  just  to  the  east  of  it  is  Clayton  Peak,  also  Archaean,  11,889  feet. 

The  rocks  of  the  Wasatch  Mountains  include  those  of  the  long  series  from  the  Cam- 
brian to  the  Upper  Cretaceous.  The  Cambrian  areas  are  lettered  C  ;  they  are  the  black 
areas  finely  lined  with  white.  The  Carboniferous  are  lettered  Cb  (Cb1,  Cb2,  Cb3)  ;  the 
Cretaceous,  Cr  (Cr1,  Cr2,  Cr3,  Cr4)  ;  the  Silurian,  S  ;  the  Devonian,  D  ;  the  Triassic,  Tr; 
the  Jurassic,  J.  The  distinguishing  markings  of  these  areas  will  be  learned  by  means  of 
the  lettering. 

The  flexures  of  these  rocks  in  the  structure  of  the  Wasatch  Mountains 
are  not  all  the  usual  up-and-down  flexures ;  there  is,  besides,  an  in-and-out 
series  between  and  about  the  Archaean  summits,  as  well  as  upon  them.  They 
may  be  traced  by  following  the  courses  of  the  black  Cambrian  areas.  Com- 
mencing at  Ogden,  there  is  first  an  eastward  bend  toward  Weber,  then  a 
westward,  back  to  the  summit  of  the  mountains ;  then,  all  the  formations 
are  gathered  into  an  east-west  trough,  or  syncline,  which  heads  through 
the  Gap,  —  the  strata  that  lie  in  the  Gap  dipping  from  the  north  and  south 
toward  its  center.  The  head,  or  western  termination,  of  the  bend  passed 
the  summit,  disastrously  to  the  extremity  of  the  flexure.  South  of  the  Great 
Gap,  the  Cambrian  and  the  rest  of  the  formations  lie  around  Clayton  Peak 


362  DYNAMICAL   GEOLOGY. 

and  Archaean  No.  4 ;  and  then  the  Subcarbonif erous  limestone  (Cb1)  bends 
over  the  summit,  saddle-like,  with  some  outcropping  Devonian  along  the 
middle.  It  is  a  complex  system  of  zigzags  in  the  great  30,000-foot  pile  of 
rock  formations.  From  the  range  of  strata  involved,  and  their  thickness,  it 
is  apparent  that  the  making  of  the  mountain  was  preceded  by  an  accumula- 
tion of  strata  from  the  top  of  the  Cretaceous  down  to  the  Archaean ;  and 
that  the  strata  were  slowly  formed  in  a  subsiding  area,  or  geosyncline,  like 
the  strata  of  the  Appalachians. 

The  relation  of  the  Wasatch  to  the  Uinta  Mountains  is  learned  by  following  the  out- 
cropping belts  from  near  Weber  southeastward  to  Echo,  and  thence  to  the  Uinta.  The 
whole  series  of  beds,  from  the  Cambrian  to  the  uppermost  Cretaceous  (the  Laramie,  Cr4, 
finely  cross-lined),  is  here  included.  The  dips  are  eastward  45°  or  more  to  Echo,  which 
has  Cr*  either  side,  where  they  are  20°,  and  then  northwestward  to  the  top  of  the  Uinta  ; 
there  is  hence  a  syncline  at  Echo,  and  an  anticline  at  the  broad  Uinta  summit,  where  the 
dip  is  4°  to  5°  north  and  south  ;  the  rock,  Cb2,  is  the  middle  Carboniferous. 

Over  the  neck  between  the  Uinta  plateau  and  the  Wasatch  Eange,  there 
is  a  large  area  of  igneous  rock  (trachyte)  lettered /(the  initial  of  fire,  or  the 
Latin  focus),  apparently  a  consequence  of  the  enormous  amount  of  warping 
in  the  great  pile  of  rocks.  Two  other  smaller  trachytic  areas  exist  to  the 
north  in  the  same  line.  The  Wasatch  and  Uinta  regions  were,  therefore, 
involved  in  a  common  system  of  profound  movements,  in  which  were  flex- 
ures and  warpings,  with  fractures  deep  enough  to  let  out  melted  rock. 
Moreover,  the  country  east  of  the  Wasatch  participated  in  the  warp- 
ing; for  the  Cretaceous  beds  occurring  over  it  have  high  dips,  and  are 
portions  of  flexures,  or  of  upturned  masses,  that  have  become  isolated  by  the 
large  amount  of  denudation  which  the  country  has  undergone,  the  excava- 
tions being  not  now  visible  only  because  they  became  filled  by  the  depo- 
sitions of  the  Eocene  Tertiary.  The  Uinta  plateau,  on  the  landward  side  of 
the  Wasatch,  has  some  relation  in  position  to  the  Cumberland  Table-land  on 
the  landward  side  of  the  Appalachians.  The  great  Uinta  mass,  20  by  150 
miles  in  area,  is  divided  by  deep  fractures  into  a  few  blocks  which  are  only 
slightly  displaced,  as  well  illustrated  by  Powell.  Seventy-five  miles  south 
of  Great  Salt  Lake,  where  the  Wasatch  Mountains  proper  may  be  said  to 
end,  there  commences  the  series  of  "high  plateaus,"  which  extends  south- 
ward to  the  borders  of  the  Colorado  Canon.  This  plateau  region  is  one  of 
great  faults,  of  few  gentle  flexures,  and  of  monoclinal  uplifts,  with  intersect- 
ing canons  as  a  result  of  its  denudation.  The  rocks  are  the  same  that  make 
the  Wasatch  and  Uinta  Mountains,  except  that  large  areas  are  covered  with 
igneous  outflows. 

The  following  cut  (Fig.  336),  by  Powell,  represents  a  portion  of  the  plateau 
region  north  of  the  Colorado  Canon,  with  its  flexures  sometimes  passing  into 
faults.  The  Colorado  River  flows  in  Marble  Canon.  The  heights  look 
small,  but  the  fault  at  W.  K.,  the  West  Kaibab  fault,  is  2000  feet  high ;  at 
E.  K.,  the  East  Kaibab,  3000  feet ;  at  T.,  the  Toroweap  fault,  700  feet ;  at 


HYPOGEIC   WORK. 


363 


H.,  the  Hurricane  fault,  about  1800  feet,  336. 

becoming  6000  at  the  Virgen  Eiver.     And 

some  of  the  plateaus  exceed  11,000  feet  in 

height.     The  long  range  of   bluffs  to  the 

eastward,  commencing  above  the  letter  E., 

is  that  of  the  Echo  Cliffs ;  and  the  upward 

bend  is  attributed  to  a  fault  of  3000  feet 

(Button). 

Ascending  the  plateaus  facing  the  Grand 
Canon  region,  the  Carboniferous  rocks  are 
left  behind,  and  a  rise  made  over  outcrops 
of  Permian,  Triassic,  Jurassic,  and  Cretace- 
ous rocks.  At  W.  K.,  and  to  the  westward, 
the  faulting  is  a  downthrow  of  the  block 
next  west,  while  east  of  it  the  displacement 
is  a  downthrow  of  the  block  next  east. 

These  plateaus  south  of  the  Wasatch 
Mountains  take  the  place  of  the  mountains, 
being  results  of  the  same  post-Cretaceous 
disturbance. 

Mr.  King,  in  his  account  of  the  Wasatch 
Mountains,  recognizes  the  principle  that  Ar- 
chaean forms  of  surface  determined  the  po- 
sitions of  lines  of  disturbance  or  uplift  in 
mountain-making  areas  of  later  time,  and 
influenced  also  the  kind  and  amount  of  dis- 
turbance. He  observes  that  the  Archaean 
ridge  which  makes  the  flank  and  partly  the 
crest  of  the  Wasatch  Range  was  the  means 
of  locating  there,  by  mechanical  resistance, 
the  great  flexures.  In  other  parts  of  the 
same  region,  where  there  are  no  Archaean 
elevations,  the  disturbance  resulted  only  in 
"high  plateaus."  He  suggests  that  the 
Uinta  plateau  may  have  been  thus  located, 
although  very  little  Archaean  rock  is  now 
in  sight  about  it. 

To  the  eastward  of  Utah,  through  Col- 
orado, along  the  Elk  Mountains,  the  San 
Juan  Mountains,  and  the  Park  regions 
farther  east,  there  are  other  more  or  less 
independent  ranges  of  contemporaneous 
origin,  and  they  are  continued  interruptedly 
into  the  northern  part  of  New  Mexico.  The  narrow  upturned  belt  at  the 
eastern  foot  of  the  Front  Range  of  Colorado,  described,  from  the  beds  near 


364  DYNAMICAL   GEOLOGY. 

Denver,  first  by  Marvine  (1873),  is  of  the  Laramide  system ;  and  it  is  con- 
tinued south  through  Huerfano  County,  into  New  Mexico  along  by  the  Eaton 
coal-field  (C.  S.  Hills).  Still  farther  south  upturned  Cretaceous  beds  extend 
along  the  trans-Pecos  region  of  western  Texas,  and  thence  into  Mexico.  But 
the  limits  of  the  several  ranges  and  their  relation  to  the  Laramide  system 
need  further  study. 

The  sketch  in  Fig.  337,  from  the  west  slope  of  the  Elk  Mountains,  in 
Central  Colorado,  shows  a  sigmoid  twist  in  the  stratification  of  the 
rocks,  the  highest  in  the  series  being  the  Cretaceous ;  the  warping  of  the 
strata  is  strikingly  exhibited.  W.  H.  Holmes  has  sections  of  flexures  and 
flexure  faults  of  the  Elk  Mountains  in  the  Hayden  Expedition  Eeport  for 
1874,  two  of  which  are  closely  like  the  form  obtained  by  Daubree  in  his 
experiments  (Fig.  326,  page  351) . 

337. 


Upturned  strata  of  the  west  slope  of  the  Elk  Mountains,  Colorado.     The  light-shaded  stratum,  Jura-Trias; 
that  to  the  right  of  it,  Carboniferous;  that  to  the  left,  Cretaceous.    Hayden's  Report. 

Igneous  ejections  attended  the  mountain-making  in  many  parts  of  the 
upturned  region,  from  Wyoming  southward,  and  some  volcanoes  may  date 
from  this  epoch. 

4.    Tertiary  Orographic  Movements  along  the  Pacific  Mountain  border. 

1.  The  great  geanticline,  —  At  the  close  of  the  Cretaceous  period  the 
latest  beds  lay  at  or  near  the  sea  level;  and  after  the  making  of  the 
Laramide  mountain-chain  the  region  was  still  but  little  above  this  level. 
During  the  Tertiary  era  following,  especially  after  the  Miocene  period,  a 
gradual  elevation  of  the  mountain  region  went  forward ;  and  now,  as  the 
result,  the  same  Cretaceous  strata  in  some  parts  of  Colorado  are  10,000  to 
11,000  feet  above  the  sea.  From  this  level  the  height  slowly  diminishes  to 
4000  feet  and  less  near  the  Arctic  coast  and  to  twice  this  in  Mexico. 

The  region  thus  placed  these  thousands  of  feet  above  the  sea  level 
probably  included  the  whole  of  the  Pacific  mountain  border,  from  the  line  of 
the  Mississippi  Valley  to  the  Pacific  coast  line,  and  outside  of  this  line  for  one 
or  more  scores  of  miles.  The  vast  geanticline  was  made  without  correspond- 
ing flexures  of  the  rocks ;  there  were  only  minor  local  bendings,  upturnings, 
and  faults.  It  was  a  very  slow  movement  upward,  continuing  probably  into 
the  Quaternary.  That  it  made  little  progress  in  Eocene  time  is  proved  by 


HYPOGEIC   WORK.  365 

the  existence  during  this  period  of  large  freshwater  lakes  over  the  summit 
of  the  mountain  region ;  for  much  rise  would  have  made  slopes  that 
would  have  drained  the  lakes  (Hayden).  The  Wasatch  and  Uinta  Eocene 
basins  of  Utah  and  Wyoming,  lettered  with  TFs  and  U's  on  the  map  (Fig. 
335),  were  two  of  these  lakes.  Miocene  lake  basins,  farther  to  the  east,  show 
that  even  in  Miocene  time  the  progress  was  slow. 

Contemporaneously,  similar  movements  were  in  progress  over  the  other 
continents :  along  the  Andes,  affecting  half,  at  least,  of  South  America;  the 
Pyrenees,  Carpathian  Alps  and  a  large  part  of  Europe  j  the  Himalayas  and 
much  of  Asia. 

2.  The  Rocky  Mountain  geosynclines. —  The  geanticline,  above  described, 
had  made  little  progress  when  local  geosynclines,  or  subsidences,  commenced 
over  the  summit  region  of  the  mountains.     The  areas  of  the  fresh-water 
lakes,  referred   to  above,  were  the  sinking  areas ;   and   the   sinking  went 
forward,  and  concurrent  deposition'  of  beds,  until  the  troughs  contained  strata 
of  Eocene  Tertiary  8000  to  10,000  feet  in  thickness  —  the  earlier  half  in  the 
Wasatch  epoch  and  the   later  in  the  Green  River.     After   these   Eocene 
basins  ceased  to  subside,  more  eastern  Miocene  and  Pliocene  geosynclines 
were  formed. 

Moreover,  an  epoch  of  upturning  and  plicating  took  place,  both  after  the 
laying  down  of  the  Wasatch  beds  and  of  the  Green  River  beds  ;  and  of  up- 
turning, in  some  places,  after  the  close  of  the  Miocene  depositions.  These 
were  local  disturbances  apparently  quite  independent  of  the  great  geanti- 
clinal  movement,  which  was  also  in  progress. 

Igneous  eruptions.  —  During  these  Tertiary  movements  the  greatest  of 
igneous  ejections  occurred  over  the  Rocky  Mountain  region  from  its  summit 
westward.  It  is  supposed  that  a  large  part  of  the  volcanoes  of  the  world 
had  their  birth  at  the  close  of  the  Cretaceous  and  during  the  Tertiary  era. 

3.  Faults  in  the  Great  Basin  and  elsewhere.  —  The  Great  Basin  has  many 
bare  ridges,  3000  to  5000  feet  above  their  bases,  standing  in  the  great  area 
of  lakes    and  alluvium-like  islands  in  a  sea.      These  ridges  trend  north- 
ward. 

There  are  outcropping  crystalline  rocks  in  some  of  the  ridges,  but  the 
rocks,  according  to  King,  are  mostly  Paleozoic,  except  west  of  the  meridian 
of  117^°  W.,  within  100  miles  of  the  Sierra  Nevada,  where  Triassic  and  Juras- 
sic rocks  occur.  The  beds  of  the  ridges  are  more  or  less  upturned,  often  in 
great  anticlines  or  synclines,  or  elsewhere  in  simple  monoclines;  but  the 
island-like  isolation  of  the  ridges  prevents  a  study  of  their  stratigraphic  rela- 
tions. King  suggested  that  the  more  western  of  the  ridges  were  perhaps 
part  of  the  Sierra  system,  which  dates  from  the  beginning  of  the  Cretaceous 
period,  or  the  close  of  the  Lower  Cretaceous ;  and  that  the  more  eastern 
were  perhaps  post-Carboniferous  in  epoch  of  disturbance. 

Among  the  Basin  Ranges,  according  to  King,  great  anticlines  characterize  the  Agui 
Range,  the  Promontory,  Gosiute,  Egan,  Peoquop,  and  Toyabe  ranges ;  the  Humboldt 
Range,  although  having  a  nucleal  axis  of  Archaean  ;  the  Pinon  Range,  in  which  the  anti- 


366 


DYNAMICAL   GEOLOGY. 


cline  is  stated  to  be  a  magnificent  arch  of  Cambrian,  Silurian,  and  Devonian  ;  the  Little 
Elko,  Cortez,  Shoshone,  Pah-Ute,  and  other  ranges.  The  same  flexed  condition  of  the 
beds  is  mentioned  by  I.  C.  Russell  as  existing  in  the  ranges  of  the  Oregon  part  of  the  Great 
Basin. 


The  ranges  of  the  Great  Basin  have  many  faults  as  well  as  flexures,  as 
described  by  Gilbert  in  1876;  and  these  faults  are  generally  downthrow 
faults.  The  following  are  two  of  his  figures  ;  they  illustrate  two  ridges  made 
up  of  blocks  displaced  as  described.  The  dip  and  the  downthrow  faults  are 
in  opposite  directions. 

338. 


East. 


Fig.  338,  section  of  Pahranagat  Range  at  Silver  Cafion,  southern  Nevada,  scale 

Timpahute  Range,  west  of  the  Pahranagat,  scale  y3Jjjn.    Gilbert,  '76. 


Fig.  889,  section  of 


Gilbert,  in  view  of  the  great  displacements  by  nearly  vertical  and  largely 
downthrow  faults,  designated  the  system  of  mountain-forming  movements 
the  "  Great  Basin  System."  He  shows  that  the  displacements  are  along  old 
fault  planes,  and  also  along  new  planes  of  fracture  made  in  the  course  of  the 
Tertiary  era,  and  later. 

Great  displacements  along  old  and  new  fault  planes  have  been  shown 
to  have  taken  place  also  in  the  high  plateaus  of  Utah  and  in  the  Uinta 
Mountains,  others  in  the  Wasatch,  and  still  others  in  the  Sierra  Nevada, 
which  are  referred  to  the  Great  Basin  System.  The  fact  of  such  move- 
ments extending  into  recent  time  has  been  urged  by  Powell,  Gilbert,  Rus- 
sell, Le  Conte,  Diller,  and  others. 


The  ridges  of  the  Great  Basin,  made  thus  of  upturned  and  plicated  rocks,  have  been 
assumed  to  be  each  limited  by  faults,  and  to  have  undergone  up  and  down  movements,  and 
variously  tilting  displacements,  and  thus  to  have  become  in  effect  "  monoclinal  orographic 
blocks"  in  the  "  Basin  System,"  —each  block  making  by  itself  a  monoclinal  mountain, 
even  when  not  so  in  its  bedding  (Russell,  1885).  In  the  ideal  sections  made  to  illustrate 
this  hypothesis,  the  wide  intervals  of  alluvium  (that  is,  of  buried  and  concealed  rock)  are 
represented  as  underlaid  each  by  a  block  at  lower  level,  or  by  the  subterranean  continu- 
ance of  one  sloping  ridge  to  the  next ;  and  the  actual  flexures  or  lines  of  bedding  have 
been  omitted,  and  monoclinal  lines  substituted.  They  are  intended  to  exhibit  the  sup- 
posed structure.  But  until  the  stratigraphy  of  the  ridges  of  the  whole  basin  shall  have 
been  studied  and  sections  of  them  represented,  and  the  relations  of  each  ridge  to  those 
lying  on  the  same  northward  or  northwestward  line  of  strike  shall  have  been  thoroughly 
investigated,  general  stratigraphic  conclusions  cannot  be  safely  drawn. 


HYPOGEIC    WORK.  367 

5.   Foreign  Examples  of  Tertiary  Mountain-making. 

1.  The  Alps.  —  Among  foreign  mountain  regions  those  of  the  Jura 
Mountains  and  the  Alps  —  the  two  combined  in  system  —  have  been  most 
carefully  studied.  The  former  are  much  like  the  Appalachians  in  flexures,  as 
first  pointed  out  by  H.  D.  Rogers.  The  Alps  have  far  greater  complexity. 
The  able  work  of  Heim  on  mountain-making,  based  on  his  study  of  the 
Toedi-Windgaellen  group,  gives  a  full  exhibition  of  the  structure  in  that  part 
of  the  Alps,  and  lays  down  many  principles  in  orography.  The  section  on 
page  102,  showing  overturn  folds,  is  reduced  from  one  of  Heim's  sections. 
One  of  the  overthrust  folds  in  the  region  has  put  the  beds  upside  down 
over  an  area  of  450  square  miles.  50,000  feet  of  formations  of  the  Jurassic, 
Cretaceous,  Eocene  Tertiary  and  Miocene  Tertiary,  were  upturned  at  the 
close  of  the  Miocene  period. 

Another  remarkable  section  of  overturn  flexures  in  the  Alps,  worked  out 
by  Kenevier,  is  represented  in  Fig.  340.  The  Dent  de  Morcles  stands  between 


Profile  of  the  Dent  de  Morcles.  Tert.  1,  Nummulitic  Eocene  Tertiary ;  Tert.  2,  Upper  Eocene  Tertiary, 
called  the  Flysch  ;  Cret.  1,  the  Neocomian  or  Lower  Cretaceous;  Cret.  2,  theUrgonian,  a  higher  division  of 
the  Lower  Cretaceous.  Scale,  -K^TH  for  height  and  length.  Renevier. 

Martigny  and  Bex  on  the  east  side  of  the  Ehone.  Cretaceous  and  Tertiary 
strata,  making  the  top  of  the  mountain,  here  lie  upside  down  on  Tertiary  and 
older  formations.  One  of  the  Tertiary  formations,  the  Upper,  is  folded  over 
on  itself.  The  overturn  is  indicated  in  the  figure  by  the  lettering.  The 
Cretaceous  strata  below  the  plane  of  the  overturn  are  absent ;  but  above  it 
there  are  two  strata  of  the  Lower  Cretaceous.  It  is  probable  that  Jurassic 
beds  once  made  the  top,  and  have  been  removed  by  denudation. 

As  stated  above,  the  Jura  Mountains,  northwest  of  the  Alps,  are  part  of 
the  Alps  mountain  system.  The  following  section  (Fig.  341)  illustrates  the 
fact  that  the  flexures  are  overthrust  in  a  northwest  direction,  like  that  in 
the  Dent  de  Morcles,  as  if  the  thrust-force  came  from  the  southeastward. 
This  direction  is  not,  like  that  in  the  case  of  the  Appalachians,  from  the 
ocean,  but  totvard  it. 

The  thickening  or  the  expanding  of  the  beds  in  the  summit  of  a  steep 


368 


DYNAMICAL   GEOLOGY. 


flexure,  and  the  thinning,  even  to  removal,  of  those  of  the  flanks  in  close- 
pressed  overthmst  flexures,  are  two  important  points  well  illustrated  in 
Figs.  118  and  119  on  page  110,  and  in  Fig.  120,  representing  the  resulting 


341. 


Section  of  the  Jura  Mountains,  along  a  line  extending  northwestward  from  Geneva  through  St.  Claude 
to  Chaux  du  Dombiel.  1,  Trias  ;  2,  Lower  Jurassic  ;  3,  Upper  Jurassic  ;  4,  Cretaceous  ;  5,  Tertiary. 
Scale,  rcsW-  P.  Choffat,  in  Heira's  Mech.  Geb. 


342. 


flexure-fault.  Fig.  342  has  a  still  greater  displacement  along  the  plane 
between  the  anticline  and  syncline,  with  a  complete  separation  of  the 
originally  continuous  beds,  as  the  numbers  on  them  show.  This  thinning 

and  faulting  are  due  to  the  friction 
between  the  overlying  and  underlying 
flexures  during  the  overthrust  move- 
ment. The  facts  teach  that  a  regular 
unfaulted  overturn  flexure,  like  that 
represented  in  the  part  to  the  right 
of  Fig.  91  (6),  on  page  103,  is  only  an 

A  flexure-fault  from  the  Alps.     Heim.  ideal  form. 

The  Alps  had  been  the  scene  of 

earlier  mountain-making  after  both  the  Archaean  and  Carbonic  eras. 
The  chain  of  the  Alps  includes,  therefore,  (1)  Archaean,  (2),  post-Carbonic, 
(3)  post-Miocene  ranges;  and  the  Juras  belong  with  the  last  in  time. 
The  proof  that  an  upturning  took  place  after  the  Carboniferous  or  Permian 
is  shown  in  Fig.  340  ;  the  Jurassic  beds  (which  include,  at  bottom,  the  Lias) 
rest  unconformably  on  the  Carboniferous,  evincing  that  a  time  of  upturning 
had  intervened.  In  the  Oriental  Alps,  the  great  upturning  was  post-Cre- 
taceous instead  of  post-Miocene. 

343. 


Post-Nummulitic  upturning  in  the  Himalayas.    La  Fouche. 

2.  Post-Nummulitic  upturning  in  the  Himalayan  Range.  —  In  the  Upper 
Indus  Valley,  Middle  Tibet,  in  the  district  of  Zanskar,  south  of  the  Indus, 
Nummulitic  limestone  (Eocene  Tertiary)  constitutes  the  summit  of  a  peak 
of  the  Singala,  having  a  height  of  19,000  feet.  In  the  section  (Fig.  343) 
the  blocked  area  is  the  Nummulitic  limestone,  a  blackish  fetid  rock ;  the 


HYPOGEIO   WORK.  369 

folded  dotted  layers  below  are  quartzytes,  and  the  beds  below,  shales. 
(La  Fouche,  India  Survey,  1888.) 

3.  Arctic  upturned  rocks.  —  Flexures  as  a  result  of  lateral  pressure  occur 
in  the  Arctic  regions.  On  Grirmell  Land,  from  Scoresby  Bay  to  Cape  Cress- 
well,  in  lat.  82°  40'  N.,  slates,  limestone,  grits,  and  quartzytes  are  in  sharp 
folds,  and  often  vertical,  with  the  strike  E.N.E.  —  Feilden  &  De  Ranee  on 
the  results  of  the  Sir  George  Nares  Expedition  in  1875-76. 

For  other  examples  of  erogenic  movements  see  pages  534,  808-812,  under 
Historical  Geology. 

CONCLUSION.  —  Orographic  work  has  been  carried  forward,  in  general,  by 
means  of  flexures,  fractures,  and  slips  or  faultirigs  along  fractures ;  and  the 
faults  have  largely  been  flexure-faults,  —  that  is,  have  been  made  in  connec- 
tion with  the  production  of  more  or  less  pronounced  flexures. 

SUBORDINATE  EFFECTS  ATTENDING  OROGRAPHIC  MOVEMENTS. 

Among  subordinate  orographic  effects  are  first,  those  incidental  to  the 
friction,  and  the  heat  thereby  produced,  namely :  (1)  part  of  metamorphism, 
(2)  of  vein-making,  and  (3)  of  volcanic  phenomena  —  subjects  already  con- 
sidered. 

Second,  those  incidental  to  the  pressure :  these  are  (4)  variations  in  the 
characters  of  flexures ;  (5)  distortions  of  beds  and  of  fossils ;  (6)  slaty 
cleavage  or  foliation;  (7)  joints. 

Third,  (8)  earthquakes. 

1.   Effects  Incidental  to  the  Pressure. 

1.  Variations  in  flexures.  —  The  characteristics  of  flexures  have  already 
been  illustrated  and  explained  (page  101).     The  pressure  producing  them 
encounters  unequal  resistance  from  inequality  of  mass  in  the  pile  of  strata 
along  the  axis  of  the  area  of  disturbance ;  from  unequal  consolidation,  or 
firmness,  or  rigidity,  in  the  beds  ;  and  also  from  friction  against  the  floor  of 
rock  beneath.     For  these  reasons  flexures  of  the  ordinary  kind  always  have 
the   ridge-line   inclined,  and   are   irregularly  distributed   along   an   area  of 
disturbance. 

The  Wasatch  Mountains  (Fig.  335)  illustrate  the  influence,  on  the  flexures, 
of  the  floor  of  rock  underneath  the  moving  strata,  and  show  that  a  flexure 
may  be  made  with  its  axis  in  the  line  of  the  pressure  and  be  thrust  forward 
end  foremost. 

The  minor  flexing  or  wrinkling  of  beds,  not  uncommon  in  the  fine  slaty 
rocks  and  schists,  is  often  occasioned  by  unequal  yielding  to  pressure  in 
the  beds,  unequal  rigidity,  unequal  contraction ;  and  it  may  also  come  from 
feeble  oscillations  in  the  action  of  the  moving  force,  and  from  the  action  of 
gravity  on  the  highly  upturned  or  vertical  beds. 

2.  Distortions   of  beds  and   their  fossils.  —  The   beds   subjected  to   the 
enormous  pressure  were  more  or  less  yielding.     Argillaceous  strata  are  soft 

DANA'S  MANUAL  —  24 


370 


DYNAMICAL   GEOLOGY. 


and  become  compressed  in  the  direction  of  the  pressure,  and  extended  at 
right  angles  to  it;  and  other  earthy  beds  have  suffered  more  or  less  in  a  like 
way.  But  strata  of  quartz  sands,  not  firmly  cemented,  have  accommodated 
themselves  to  the  pressure  in  part  by  rearrangements  of  the  grains ;  and  those 
of  limestone,  and  hard  quartzyte,  brittle  rocks,  mostly  by  fracturing,  displace- 
ment, and  recementation. 

The  distortions  of  fossils  vary  according  to  the  relation  in  position  be- 
tween the  planes  of  bedding  or  cleavage  of  the  rock,  and  the  axial  plane  at 
right  angles,  or  nearly  so,  to  the  direction  of  pressure.  The  inequalities  in 
the  pressure  and  in  the  varying  resistances  to  motion  were  a  cause  of  a  warp- 
ing of  the  beds  on  a  large  scale,  which  had  its  effects.  Hence  stretchings, 
slippings,  and  contractions  of  fossils  are  common  in  such  beds. 

Some  examples  are  shown  in  the  following  figures  from  a  paper  by  D.  Sharpe  (1847, 
Q.  J.  G-.  Soc.},  illustrating  cases  observed  by  him  in  a  slate  rock  in  Wales.     They  repre- 
sent two  species  of  shells,  the  Spi- 

344.  rifer  disjunctus  (Nos.  1  to  4)  and 

the  Spirifer  giganteus  (Nos.  5  to 
8).  No.  1  is  the  natural  fprm  of 
8.  disjunctus ;  the  others  are  dis- 
torted. The  lines  zz  show  the 
lines  of  cleavage  in  the  slate:  2 
lay  in  the  rock  inclined  60°  to  the 
planes  of  cleavage,  and  is  short- 
ened one  half ;  3  lay  obliquely  at 
an  angle  of  10°  or  15°,  and  short- 
ened above  the  middle  and  length- 
ened below  it ;  4  is  a  cast,  the 
upper  part  pressed  beneath  that 
shown,  while  the  lower  is  much 

drawn  out ;  5  is  like  3,  the  angle  with  the  cleavage-plane  being  less  than  5°,  and  the  lower 
part  has  lost  its  plications  by  the  pressure  and  extension  ;  6  has  a  similar  angle  to  the 
cleavage-plane,  but  a  different  position  ;  7  intersects  the  cleavage-plane  at  only  1°,  and  its 
lower  part  is  very  much  elongated.  Compression,  a  sliding  of  the  rock  at  the  cleavage- 
planes,  and  more  especially  a  spreading  of  the  rock  itself  under  the  pressure,  are  the 
causes  which  have  produced  these  distortions.  All  fossils  are  liable  to  become  similarly 
misshapen  under  the  same  conditions. 

3.  Foliation,  slaty  structure. — Koofing  slates  exemplify  cleavage-struc- 
ture, or  foliation.  They  are  most  common  on  the  outskirts  of  regions  of 
disturbance.  Slaty  cleavage  often  graduates  into  the  foliated  structure  of 
hydromica  and  mica  schists.  The  fact  that  slaty  structure  is  not  coincident 
with  the  bedding-planes  was  explained  by  Sedgwick  in  1835,  from  observa- 
tions in  Wales.  Sorby  first  pointed  out  (1849)  that  the  structure  was  due  to 
the  forcing  of  all  flattened  and  linear  particles  into  parallel  planes,  approxi- 
mately perpendicular  to  the  pressure ;  and  that  all  air-cavities  and  particles 
of  moisture  are  flattened  likewise.  He  sustained  his  conclusions  by.  micro- 
scopic examinations,  and  by  subjecting  to  pressure  clay  and  scales  of  oxide 
of  iron.  Tyndall  rendered  beeswax,  clay,  and  other  substances,  laminated 


HYPOGEIC   WORK.  371 

by  simple  pressure;  and  later  Daubree,  who  experimented  with  clay  and 
scales  of  mica,  obtained  a  perfect  schistose  structure.  The  rolling  and  ham- 
mering of  metals  result  in  a  laminated  texture,  which  fracturing  or  acids 
may  reveal,  when  not  otherwise  visible ;  and  several  fine  examples  are  fig- 
ured by  Daubree  in  his  excellent  work  on  Experimental  Geology. 

Mountain-making  was  going  forward,  and  the  work  done  was  therefore  on 
a  large  scale,  producing  at  one  effort  slaty  structure  over  areas  of  hundreds 
of  square  miles,  with  great  uniformity  of  direction  and  high  angle  of  pitch. 
Sedgwick  recognized  the  approximate  coincidence  of  the  strike  of  the  slates 
with  the  strike  of  the  beds,  or  rather,  as  Professor  Phillips  stated  it,  with 
the  direction  of  the  main  axis  of  elevation.  The  uniformity  of  product  and 
evenness  of  surface  are  a  consequence  of  the  fineness  and  evenness  of  grains 
of  the  original  argillaceous  formation,  and  the  regularity  of  the  long-con- 
tinued pressure ;  but  partly  also  of  the  moderate  degree  of  heat  during  the 
action  of  the  pressure. 

Further :  pressure  has  been  proved  to  have  produced  a  foliated,  and  even 
a  schistose,  structure  in  the  granite-like  rock,  of  igneous  origin,  called 
granulyte,  and  also  in  augitic  and  other  igneous  rocks. 

A  slaty  formation  often  contains  fossils,  and  these  indicate,  to  some  extent,  the 
degree  of  compression  and  distortion  which  the  beds  containing  them  underwent  under  the 
pressure.  The  fossils  in  Fig.  344  are  from  a  paper  on  slaty  cleavage.  This  subject  has 
been  treated  mathematically  by  Professor  Haughton  (1846,  1857);  and  more  recently  by 
A.  Harker  (British  Association,  1885). 

Slaty  cleavage,  or  that  characterizing  roofing  slates,  passes  gradually  into  the  foliation 
of  hydromica  schist  and  mica  schist,  and  thence  into  that  of  gneiss  and  gneissoid  granite, 
suggesting  that  the  latter  may  be  due  in  these  rocks  to  pressure.  This  has  been  confirmed 
by  experiment  and  observation.  But  geological  observation  is  required  to  settle  any 
doubts  that  arise,  rather  than  the  microscope.  In  general,  the  foliation  of  mica  schist 
and  gneiss  is  not  a  result  of  pressure,  but,  on  the  contrary,  of  the  original  bedding  of  the 
formation.  The  evidence  of  this  often  appears  in  the  occurrence  of  large  variations  in 
strike  and  dip  in  the  planes  of  foliation,  instead  of  the  high  angle  and  evenness  character- 
izing slates  ;  in  flexures  of  the  sheets  of  rock,  anticlinal  or  synclinal ;  and  in  alternations 
of  the  sheets  with  those  of  limestone  or  other  kinds  of  rock,  such  alternations  hi  connec- 
tion with  low  dips  or  flexures  being  good  evidence  that  the  sheets  are  true  beds.  Only 
the  finer  kinds  of  metamorphic  rocks  —  argillyte  and  hydromica  schist — often  lose  their 
bedding  by  the  substitution  of  the  cleavage  structure  through  pressure. 

4.  Joints. — Joints  in  rocks  (see  page  111)  have  various  methods  of 
origin.  They  are  in  part  due  to  slow-acting  pressure  on  the  outskirts  of  a 
region  of  disturbance.  The  pressure  may  act  with  little  or  no  warping  of 
the  beds.  That  this  is  often  the  case  is  indicated  by  the  general  parallelism 
in  the  joints.  But  in  other  cases  warping  or  torsion  is  strongly  marked,  as 
Daubree  has  shown.  Daubree  has  illustrated  the  effects  of  torsion  on  the 
courses  of  joints  by  subjecting  plates  of  ice  to  the  action.  He  obtained,  as 
one  of  his  results,  with  a  plate  nearly  a  yard  long,  the  fractures  shown  on 
a  much  reduced  scale  in  Fig.  345.  Fig.  346  shows  a  portion  of  one  of  the 
plates  one  fourth  of  the  natural  size.  (It  is  from  a  photograph,  and  hence 


372 


DYNAMICAL    GEOLOGY. 


346. 


345. 


the  reflections  from  the  surfaces  of  fracture  give  a  false  appearance  of  ridges 
along  the  fractures.)  Daubree  draws  attention  to  (1)  the 
approximate  parallelism  of  the  lines,  and  yet  their  slight 
divergence  ;  (2)  the  crossing  of  one  set  of  lines  by  an- 
other nearly  at  right  angles,  anti-parallels,  as  he  calls 
them ;  (3)  the  fact  that  the  lines  are  in  groups ;  (4)  the 

fact  that  joints  may  be 
an  instantaneous  effect ; 
(5)  the  very  important 
fact  that  the  force  pro- 
ducing the  joints  did  not 
act  at  right  angles  to 
either  set,  but  at  the 
extremity  of  a  bisectrix 
to  the  angle  of  intersec- 
tion of  the  two  sets ; 
and  (6)  the  fact  that 
the  slower  the  action 
of  the  force  and  the 
larger  the  plates,  the 
nearer  the  approach  to 
parallelism  between  the 
lines  in  each  set.  Fract- 
ures made  by  torsion 
might  be  left  open  when 
those  from  direct  pres- 
sure would  remain 
closed.  Other  instruc- 
tive figures  are  given  in 
his  work  on  Experimen- 
tal Geology.  Joints  may  also  be  due  to  the  vibrations  of  earthquakes 
(Crosby),  and  to  changes  of  temperature  (pages  260,  264). 

2.    Earthquakes. 

An  earthquake  is  a  series  of  vibrations  begun  in  some  region  of  local  dis- 
turbance in  the  earth's  crust,  and  propagated  upward  and  outward  from  this 
place  as  a  center.  Slight  tremors  may  be  produced  by  falls  of  large  rock- 
masses,  where  undermining  has  been  carried  on.  But  true  earthquakes 
come,  for  the  most  part  at  least,  from  one  or  the  other  of  the  following 
sources  of  disturbance  :  — 

(1)  Vapors  suddenly  produced,  causing  ruptures  and  friction;  or,  com- 
monly, (2)  sudden  movements  or  slips  along  old  or  new  fractures. 

Earthquakes  due  to  the  former  of  these  methods  are  common  about  vol- 
canoes. At  the  Hawaiian  Islands,  shakings  that  are  destructive  over  the 
island  of  Hawaii  at  the  moment  of  some  of  the  more  violent  eruptions  do 


Lines  of  fracture  produced  in  a  plate  of  ice 
(GG)  by  slight  torsion,     (x  ^a.) 


Portion  of  a  plate  of 
ice  showing  its  fract- 
ures (x|).  From  a 
photograph. 


HYPOGEIC   WORK.  373 

not  often  affect  the  island  of  Oahu,  a  depth  of  500  fathoms  of  water,  the  least 
depth  between  the  two  islands,  being  sufficient  to  stop  off  the  vibrations. 
Milne  states  that  Japan,  a  country  noted  for  volcanoes,  averages,  some  years, 
an  earthquake  a  day ;  and  that  in  two  years,  in  north  Japan,  154  out  of  387 
shook  an  area  of  less  than  50  miles,  and  a  few  of  the  larger  shocks,  an  area 
of  about  150  miles. 

Earthquakes  of  the  second  mode  of  origin  may  occur  in  all  regions,  vol- 
canic or  not.  They  have  their  origin  mostly  in  the  vicinity  of  mountain 
regions  where  old  fractures  most  abound.  The  vibrations  may  be  begun  in 
a  slip  of  a  few  inches,  or  feet,  but  when  there  has  been  a  succession  of  slips, 
up  and  up  for  10,000  feet  and  more,  as  in  the  faults  of  the  Appalachians, 
earthquakes  of  inconceivable  violence  must  have  resulted. 

Earthquake  vibrations  have  been  supposed  to  be  due  to  wave-like  movements  in  the 
interior  liquid  mass  of  the  globe,  and  Professor  A.  Perrey  of  Dijon  concluded  that  the 
greatest  number  of  earthquakes  occurred  at  the  season  of  the  syzygies  in  each  lunar 
month,  synchronous  with  the  tides  in  the  ocean.  But  if  the  earth  is  solid  throughout,  the 
facts  have  another  explanation. 

The  observations  of  Professor  W.  H.  Mies  on  the  gneiss  of  a  quarry  at  Monson,  Mass. , 
show  that  even  the  solid  rocks  are  in  some  places  under  a  strain  ;  for  he  states  that  bendings, 
sudden  fractures,  and  expansions  of  the  rock  often  take  place;  masses,  before  their  ends 
are  detached,  become  bent  upward  at  middle  ;  and  one  mass,  354  feet  long,  11  wide,  and 
3  thick,  was  an  inch  and  a  half  longer  after  it  was  detached  than  before,  showing  a  strain 
which  was  greatest  in  a  direction  from  north  to  south  —  an  effect  due  to  compression  by 
the  pressure  the  rocks  had  been  subjected  to,  and  a  consequent  expansion  in  a  transverse 
direction.  All  are  familiar  with  the  crackling  sounds  occurring  at  intervals  in  a  board 
floor  of  a  house,  arising  from  change  of  temperature,  especially  in  winter  in  a  room 
that  is  heated  only  during  the  day ;  and  with  the  more  common  sounds  of  similar  char- 
acter from  the  jointed  metallic  pipe  of  a  stove  or  furnace,  given  out  after  a  fire  is  first 
made,  or  during  its  decline.  In  each  case,  there  is  pressure  or  tension,  accumulating 
for  a  while  from  contraction  or  expansion,  which  relieves  itself,  finally,  by  a  movement  or 
slip  at  some  point,  though  too  slight  a  one  to  be  perceived ;  and  the  action  and  effects  are 
quite  analogous  to  those  connected  with  the  lighter  kind  of  earthquakes. 

The  earthquake  of  Lisbon,  in  1755,  which  threw  down  the  greater  part  of  the  city,  and 
in  six  minutes  caused  the  death  of  60,000  persons,  disturbed  an  immense  area,  it  being  felt 
at  Algiers  and  Fez  as  severely  as  in  Spain  and  Portugal,  in  the  Alps,  Great  Britain,  on 
the  Baltic,  and  in  northern  Germany.  The  effects  from  sea- waves  were  of  wide  extent, 
but  such  waves  may  be  propagated  across  an  ocean  from  the  vibrations  of  a  coast  region. 

An  earthquake  on  the  4th  of  January,  1843,  reported  upon  by  Professor  H.  D.  Rogers 
(1843),  "was  felt  from  the  seacoast  of  Georgia  and  South  Carolina  to  and  beyond  the 
western  frontier  military  posts,  and  from  the  latitude  of  Natchez  to  that  of  Iowa,  a 
distance  in  each  direction  of  about  800  miles  ;  and  there  are  reasons,"  Professor  Rogers 
adds,  "for  believing  that  its  actual  extent  was  much  greater.  Its  course  was  from 
N.N.W.  to  S.S.E.,  and  its  rate  of  progress  about  2800  to  3000  feet  a  second,  and 
equable  in  rate. 

The  Charleston  (S.C.)  earthquake  of  August  31,  1886,  which  threw  down  many 
buildings  in  the  city,  was  felt  from  the  Carolina  coast,  Georgia,  and  central  Florida, 
northward  to  southern  New  England,  and  across  New  York  to  Ontario  in  Canada,  and 
westward  to  eastern  Louisiana,  Arkansas,  Missouri,  and  Iowa,  an  area  800  miles  wide  by 
1000  miles  from  north  to  south.  Its  course  was  the  reverse  of  that  of  1843.  It  was 
scarcely  appreciable  in  sea  disturbance. 


374  DYNAMICAL   GEOLOGY. 

Volcanoes  stand  on  lines  of  fractures  in  the  opening  of  which  their 
existence  began ;  and  subsequently,  through  geological  time,  slips  up  or 
down  may  have  occurred  along  such  fractures  in  the  earth's  uneasy  crust, 
independent  of  local  action,  producing  earthquakes,  and,  perhaps,  also 
initiating  eruptions.  The  Mediterranean  area  is  one  of  the  earth's  fire 
regions,  from  its  eastern  to  its  western  limit,  and  its  borders  are  noted  for 
the  relative  frequency  of  earthquakes  ;  and  these  earthquakes,  in  the  majority 
of  cases,  are  independent  of  action  in  the  volcanoes  of  the  era.  This  is  true 
also,  according  to  Milne,  of  the  greater  earthquakes  of  Japan. 

The  New  Zealand  Tarawera  eruption  of  1883,  which  blew  out  with  explo- 
sive violence  for  a  day  or  two,  was  followed,  three  days  after  it  had  subsided, 
by  an  outbreak  in  White  Island,  an  active  volcano  in  the  Bay  of  Plenty,  and, 
two  months  later,  by  a  violent  eruption  on  the  island  of  Ninafou  in  the  Tonga 
group.  The  three  volcanic  regions  are  on  the  same  island  line  of  the  ocean, 
the  northeast  or  New  Zealand  line,  which  is  one  of  the  most  marked  in  the 
Pacific.  It  may  be  that  this  succession  of  disturbances  was  due  to  a  slight 
movement  from  north  to  south  along  the  old  fracture-plane,  through  the 
opening  of  which  the  range  of  islands  began  its  existence. 

The  -central  region  of  an  earthquake  vibration,  which  may  have  con- 
siderable breadth  or  length,  or  have  the  course  of  a  long  fissure,  is  called 
the  epicentrum.  The  rock-waves  move  off  from  it  in  all  directions,  but  often 
most  forcibly  in  one.  The  waves  are:  (1)  waves  of  compression,  or  conden- 
sation, in  which  the  vibrations  are  normal  to  the  origin,  or  in  the  direction 
of  the  movement  of  the  wave ;  and  (2)  waves  of  distortion,  or  transverse 
waves.  The  sounds  of  earthquakes  are  attributed  by  Milne  to  preliminary 
tremors  preceding  the  principal  shock,  which  have  the  more  rapid  movement 
required  to  produce  sound. 

The  amplitude  of  the  wave  varies  from  less  than  a  millimeter  to  possibly 
a  foot.  But  destructiveness  depends  more  on  rate  of  vibration  than  on  am- 
plitude. Milne  observes  that  the  greater  the  initial  impulse,  the  greater  the 
speed  of  propagation ;  and,  as  the  propagation  widens  radiately,  the  velocity 
of  propagation  decreases,  the  period  usually  becoming  larger. 

C.  Davison  (1891)  traces  several  earthquakes  of  Great  Britain  to  slips  along  faults. 
He  observes  that  from  the  central  portions  of  the  slip-area  will  come,  as  a  rule,  the  vibra- 
tions of  largest  amplitude  and  longest  period,  and  from  its  margin,  and  especially  toward 
the  surface,  minute  vibrations  of  a  period  so  short  that  they  'may  be  perceptible  only  as 
sound.  He  thus  explains  the  fact  "  that  the  sound-area  is  not  concentric  with  the  dis- 
turbed area,  and  the  sound- focus  is  nearer  the  surface  than  the  rest  of  the  seismic  focus  "  ; 
and  also,  "the  fact  that,  in  great  earthquakes,  the  sounds  are  heard  only  within  a  compara- 
tively small  area  immediately  around  the  epicentrum."  Liability  to  slips,  and  therefore  to 
earthquakes,  diminishes  with  the  progress  of  time. 

Kinds  of  rocks  have  great  effect  on  the  propagation.  Milne  obtained  in  Japan,  for 
velocities  of  propagation,  from  200  feet  per  second  to  630  feet ;  Mallet  obtained,  for  sand, 
a  rate  of  825  feet,  and  for  granite,  of  1665  feet;  Newcomb  and  Dutton,  in  the  Charleston 
earthquake,  made  out  a  rate  of  17,000  feet  per  second,  without  any  indications  of  variation 
in  the  speed ;  H.  L.  Abbott  in  his  observations  on  explosions  at  Hallet's  Point  in  1876, 


HYPOGEIC   WORK.  375 

4500  to  20,000  feet  per  second ;  and  Fouque  found  the  velocity  in  granite  9200  feet  per 
second. 

The  position  of  the  epicentrum  is  ascertained  by  noting  the-direction  of  throw  of  over- 
turned columns,  walls,  houses,  the  converging  lines  pointing  to  the  region  of  the  surface 
vertically  over  the  epicentrum.  An  oblique  thrust  is  most  effective  in  overthrowing 
objects  ;  and  the  particular  belt-line  around  the  central  region  along  which  the  waves  are 
most  destructive  is  called  the  meizoseismic  curve,  and  lines  of  equal  disturbance,  isoseis- 
mic  curves.  Such  curves  are  far  from  circles. 

By  means  of  evidence  from  fractures  in  walls  and  overturned  objects,  R.  Mallet  in- 
ferred the  angle  of  emergence  of  the  wave,  and  so  calculated  the  depth  of  the  center  of 
disturbance.  From  26  observations  of  the  Neapolitan  earthquake  of  1857  he  deduced  a 
depth  of  6^  miles.  C.  E.  Dutton,  in  his  paper  on  the  Charleston  earthquake,  assumes 
that  the  total  disturbance  is  inversely  as  the  square  of  the  distance  from  the  center  of 
disturbance.  By  noting,  in  the  Charleston  earthquake,  the  circle  about  the  epicentrum  at 
which  the  total  effect  diminished  most  rapidly  on  going  from  the  epicentrum,  he  deduced 
depths  of  8  and  12  miles  for  two  distinct  centers  of  disturbance. 

The  instruments  by  which  the  earthquake  movements  are  detected  (seismoscopes) , 
measured  (seismometers^ ,  and  recorded  (seismographs),  are  of  many  kinds.  Those  which 
experience  in  Japan  has  proved  to  be  most  accurate  are  the  so-called  Duplex  pendulum ; 
the  Bracket  seismographs  of  Chaplin,  Ewing,  Gray,  or  Milne  ;  and  conical  pendulums. 

The  geological  effects  of  earthquakes  are  small,  while  those  of  the  causes 
which  produce  earthquakes  are  large.  Vibrations  loosen  rocks  and  may  tumble 
them  down  precipices,  as  they  tumble  down  houses  and  walls.  Occasionally 
they  produce  some  rotation  in  the  objects  moved  where  the  object  is  not 
equably  attached  below.  They  may  fracture  the  rocks  and  ground  in  the  re- 
gion of  greatest  disturbance.  They  often  occasion  the  drying  up  of  springs. 

In  Calabria,  in  1783,  fissures  were  made  that  were  over  a  mile  long,  100 
feet  wide,  and  200  feet  deep.  In  the  Charleston  earthquake  of  1886,  and 
also  in  that  of  1892  at  Quetta,  in  British  Baluchistan,  described  by  C.  Davison, 
railway  lines  were  bent ;  and  in  the  latter  case,  on  removing  the  bent  rails 
for  repair,  the  new  lines  had  to  be  cut  2|  feet  shorter  than  the  old  ones, 
owing  to  a  permanent  displacement. 

But  these  rending  effects  and  the  uplifts,  and  other  results  attending 
them,  are  effects  rather  of  the  deep-seated  cause  of  the  vibration  and  the 
fracturing.  Besides  these  effects,  earthquakes  may  destroy  life  in  the  sea, 
by  impact,  as  a  blow  on  the  ice  of  a  pond  will  stun  or  kill  the  fish.  They 
may  also  throw  the  ocean  over  the  land  in  waves  of  30  to  100  feet,  carrying 
in  the  animals  of  the  sea,  and,  in  these  modern  times,  man's  boats  and  ships, 
besides  lifting  and  bearing  far  inland  sea-bottom  rocks  and  sand,  and  great 
masses  of  coral  rock  on  the  shores  of  coral  islands  (page  222).  Further:  if 
a  mountain-system  of  the  length  of  an  America  were  making,  like  the  post- 
Cretaceous  Laramide  System,  and  a  like  system  cotemporaneously  in  the 
other  America,  sea-borders,  continental  seas,  and  land-borders  the  world  over 
might  be  mostly  stripped  of  life  by  earthquake  waves.  Or,  if  the  mountain 
systems  in  progress  were  of  less  extent,  like  the  post-Paleozoic,  a  hemi- 
sphere might  experience  the  devastations,  and  austral  land-borders  and 
sea-borders  escape. 


376  DYNAMICAL   GEOLOGY. 

ORIGIN  OF  THE  EARTH'S  FORM  AND  FEATURES. 

This  embraces  first,  the  origin  of  the  shape  of  the  earth's  mass ;  second, 
the  origin  of  continental  plateaus  and  oceanic  depressions,  and  of  all  move- 
ments in  the  earth's  crust  through  geological  time  not  involving  erogenic 
work ;  and,  third,  the  origin  of  the  movements  producing  the  upturning  of 
formations  and  the  making  of  mountains. 

The  first  of  these  subjects,  geogenic  work,  pertains  to  astronomy.  The 
movements  referred  to  under  the  second,  by  which  wide  changes  of  level 
have  occurred  without  special  orogenic  results,  except  displacements  along 
old  or  new  fracture-planes,  have  been  termed  by  G-.  K.  Gilbert  epeirogenic,  or 
continent-making  (1890).  The  work  included  under  the  third  head  is  orogenic. 

1.    GENERAL  CONSIDERATIONS  BEARING  ON  THE  EARTH'S  FORM. 

1.  Solidification  of  the  earth.  —  The  earth  solidified  from  the  center  out- 
ward. This  conclusion  is  established  on  the  evidence  that  pressure  raises 
the  fusing  point  of  rocks.  The  globe  was,  therefore,  never  in  a  state  of 
complete  liquidity.  According  to  Clarence  King,  experiments  made  for  him 
by  C.  Barus  with  reference  to  the  question  as  to  the  earth's  rate  of  cooling 
(see  page  1026),  lead  collaterally  to  the  conclusion  that  the  depth  of  the 
liquid  exterior  of  the  globe  has  at  no  time  exceeded  50  miles. 

The  study  of  meteorites  has  led  some  astronomers  and  writers  on  the  constitution  of 
the  globe  to  the  opinion,  in  view  of  the  iron  in  these  bodies,  and  the  fact  that  their  place 
in  the  solar  system  is  to  a  large  extent  near  that  of  the  earth,  that  the  earth's  interior  con- 
sists, for  the  greater  part,  of  iron.  This  view  is  favored,  also,  by  the  high  percentage  (10 
to  14)  of  iron  oxide  in  most  igneous  rocks ;  the  existence  of  much  native  iron  in  doleryte 
at  Disco  Island,  Greenland ;  and  the  occurrence  of  the  greatest  of  iron-ore  beds  of  the 
world  in  the  oldest  rocks,  the  Archaean.  Platinum,  gold,  silver,  and  copper  are  heavier 
metals  ;  but  it  is  remarkable  that  they  are  not  brought  up  among  the  constituents  of  erup- 
tive rocks,  as  iron  is,  but  are  obtained  from  the  supercrust  and  its  veins :  as  if  these  metals, 
in  consequence  of  being  in  vaporizable  combinations,  or  those  of  comparatively  little  spe- 
cific gravity,  were  near  the  surface  of  the  fused  globe,  while  below  these  were  the  iron  and 
whatever,  under  the  conditions,  could  form  alloys  with  it.  If  the  earth  is  two  thirds  iron, 
or  iron  to  within  500  miles  of  the  surface  (without  much  increase  in  the  density  of  the  iron 
downward),  and  the  rest  were  made  chiefly  of  basaltic,  or  dolerytic,  material,  it  would 
have  about  its  present  specific  gravity,  5-5. 

The  complete  solidification  of  the  earth  is  held  to  be  its  present  condition 
by  most  physicists  who  have  recently  discussed  the  subject.  This  implies  that 
the  crust  that  was  formed  over  the  surface  of  the  liquid  stratum  by  cooling 
had  continued  to  thicken  until  the  whole  was  solid.  The  evidence  favoring 
the  earth's  essential  solidity  has  been  obtained  by  investigating  mathemati- 
cally the  amount  of  deformation  which  the  sphere,  if  a  liquid  mass  enveloped 
in  a  thin  crust,  should  undergo  during  its  revolution  ;  and  also  the  effect  of 
such  tidal  movement  in  the  earth's  mass  on  the  height  of  the  oceanic  tides. 
Kelvin  concludes,  on  these  grounds,  that  the  earth  must  have  an  effective 
rigidity  at  least  as  great  as  that  of  steel  (1862,  1872).  G.  H.  Darwin  has 


HYPOGEIC   WORK.  377 

sustained  the  same  conclusion,  stating  that  "  if  it  were  true  that  the  earth 
is  a  fluid  ball  coated  with  a  crust,  that  crust  must  be  of  fabulous  rigidity  to 
resist  the  tidal  surgings  of  the  subjacent  fluid"  (1888).  At  the  same  time, 
according  to  the  same  authority,  the  weight  of  the  water  of  a  high  flood-tide 
probably  occasions,  owing  to  the  elasticity  of  the  crust,  "  a  local  elastic  yield- 
ing along  the  coast-line  of  continents";  and  "  there  is  reason  to  believe 
that  such  flexure  has  actually  been  observed  by  a  delicate  form  of  level  on 
the  coast  of  the  Bay  of  Biscay."  Newcomb  favors  the  same  conclusion  in  a 
paper  discussing  the  cause  of  the  periodic  variations  of  latitude  (1893). 

0.  Fisher,  of  Cambridge,  England,  questions  the  above  conclusion  from 
the  tides  (1892).  Basing  his  mathematical  calculations  on  an  investigation 
by  Darwin  of  the  tides  upon  a  yielding  earth  according  to  the  canal  theory, 
he  obtains  the  result,  that  the  height  of  the  tide  for  a  liquid  earth  would  be 
only  a  fifth  less  than  that  for  a  rigid  earth,  and  suggests,  as  the  difference 
is  so  small,  that  the  existing  tides  may  have  just  the  height  appropriate  to 
a  liquid  interior.  He  observes,  further,  that  the  heat  generated  within  the 
earth  by  the  tides  in  the  earth's  mass  from  their  commencement  —  calcu- 
lated by  Darwin  to  be  sufficient  "  to  give  a  supply  of  heat,  at  the  present 
rate  of  loss,  for  3560  millions  of  years "  —  would  have  been  only  to  a 
small  extent  expended  or  wasted,  and  that,  through  convection  currents, 
it  keeps  the  liquid  layer  in  fusion,  and  prevents  the  crust  from  growing 
thicker.  Other  considerations  have  led  Fisher  to  make  the  thickness  of  the 
crust  about  18  miles.  The  conclusion  of  Fisher  is  objected  to  by  G-.  F.  Becker, 
on  the  basis  of  calculations  which  lead  him  to  the  conclusion  that  "for  a 
fluid  earth  the  canal  theory  and  the  equilibrium  theory  give  the  same  result, 
viz.:  no  relative  tide."  He  adds,  that  "on  any  theory  of  the  tides,  the  ex- 
istence of  semi-diurnal  tides  indicates  an  earth  presenting  great  resistance 
to  deformation"  (1893). 

2.  Earth-shaping.  —  Whether  solid  to  the  surface  or  not,  the  earth  is 
believed  to  be  so  far  fluid-like  in  its  mass  as  to  admit  of  adjustments  to 
gravitational  pressure  through  molecular  flow,  if  not  through  a  liquid  layer, 
and  to  owe  its  shape  primarily  to  the  principle  of  gravitational  equilibrium, 
as  if  liquid.  This  view  of  adaptation  to  gravitational  pressure  was  rec- 
ognized geologically  by  Herschel  in  his  Appendix  to  Babbage's  Ninth  Bridge- 
water  Treatise  (1837),  where  he  attributed  changes  of  level  to  "changes  in 
the  incidence  of  pressure  on  the  general  substratum  of  liquefied  matter  which 
supports  the  whole,"  and  argued  therefrom  that  the  rise  in  level  going  on  in 
Scandinavia  might  be  caused  by  the  accumulation  of  sedimentary  deposits 
over  the  adjacent  ocean  bed.  The  earth's  interior  liquidity  was  then  gen- 
erally admitted.  In  1888,  C.  E.  Dutton  proposed  the  term  isostasy  for  "  the 
condition  of  equilibrium  to  which  gravitation  tends  to  reduce  a  planetary 
body  irrespective  of  whether  it  be  homogeneous  or  not,"  that  is,  whether 
solid  to  the  surface  or  partly  liquid  beneath  it,  and  whatever  its  constitution. 

The  rate  of  adjustment  to  changing  load  would  necessarily  be  very  slow 
in  a  solid  globe,  in  which  'it  could  take  place  only  through  molecular  flow  in 


378  DYNAMICAL  GEOLOGY. 

the  mass,  while  it  might  be  comparatively  rapid  if  a  liquid  layer  existed 
beneath  a  thin  crust  —  a  flotation  crust,  as  it  has  been  called.  Darwin 
has  remarked  that  through  molecular  movements  the  earth's  spheroidal  form 
might  change  with  change  of  rotation.  But  what  is  the  minimum  limit  in  a 
solid  globe,  to  rate  of  adjustment  —  that  is,  to  the  rate  at  which  resistances 
from  cohesion  and  other  causes  can  be  overcome  —  no  known  facts  have  even 
approximately  indicated.  Effects  should,  in  any  case,  lag  behind  the  cause 
of  change,  whether  they  are  those  from  the  deposition  or  removal  of  a  load. 

There  are,  however,  facts  that  seem  to  imply  a  somewhat  easy  adjust- 
ment. Many  low  coasts  over  which  sediments  are  borne  to  the  sea  border 
are  known  to  be  slowly  sinking ;  as,  for  example,  the  coast  of  New  Jersey, 
where  the  rate,  according  to  G.  H.  Cook,  is  two  feet  a  century.  This  sink- 
ing, and  that  of  other  parts  of  the  Atlantic  border,  is  attributed  by  Cook  to 
gravitation  in  the  sediments.  W.  J.  McGee,  in  a  paper  of  1892,  has  brought 
together  many  facts  from  various  coasts,  mostly  adjoining  the  mouths  of 
rivers,  bearing  in  the  same  direction.  On  the  Netherland  coast,  the  rate  of 
sinking,  according  to  Girard,  is  0-09  to  0-75  meter  per  century,  and  0-26 
meter  since  1732.  But  actual  sinking  is  not  a  legitimate  isostatic  effect. 
The  subsidence  on  such  coasts  corresponding  to  the  amount  of  contributed 
sediments  (not  exceeding  it)  is  not  indicated  by  the  amount  of  sinking,  for 
the  sinking  is  in  excess  of  it.  Other  facts  are  more  decisive.  A  boring  on 
the  southeast  coast  at  Atlantic  City,  1398  feet  deep,  extended  through  beds, 
as  stated  by  J.  C.  Smock,  which  were  proved  by  the  fossils  to  be  Miocene ; 
Turritella  plebia  occurring,  according  to  Heilprin,  at  450  feet,  and  Perna 
maxillata  at  760  feet,  of  which  depth  265  feet  are  surface  gravels  and  265 
beyond  are  of  doubtful  reference.  But  at  Asbury  Park  and  Ocean  Grove, 
farther  north,  wells  afforded  the  Upper  Greensand  with  Terebratula  Harlani 
and  other  Upper  Cretaceous  fossils  at  a  depth  severally  of  only  270  and  280 
feet  below  tide  level,  and  the  Lower  Greensand  at  365  and  382  feet.  The 
facts  indicate  a  very  slow  rate  of  subsidence  at  Asbury  Park  since  the  Cre- 
taceous period,  and  much  less  slow  at  Atlantic  City,  which  is  80  miles  south 
of  Asbury  Park  and  only  40  from  the  north  cape  of  Delaware  Bay.  A  boring 
on  the  coast  of  Texas  passed  through  3070  feet  of  shore  deposits,  without 
reaching,  according  to  the  investigations  of  G.  D.  Harris,  beyond  the  Miocene. 
The  deposits  down  to  a  depth  of  458  feet  are  pronounced  Quaternary. 
Beyond,  to  the  1511-foot  level  no  Tertiary  fossils  were  found  and  all  of  them 
may  still  be  Quaternary.  Between  1511  and  2153  feet,  the  deposits  were 
Upper  Tertiary  as  shown  by  fossils  ;  and  between  2153  and  2920  feet,  Upper 
Miocene.  In  the  lower  150  feet,  clays  and  sands  were  found  without  fossils. 
Similar  facts  are  reported  from  the  delta  of  the  Ganges  and  other  regions. 

These  proofs  of  rather  rapid  subsidence  along  coasts  are  regarded  by 
many  as  not  inconsistent  with  the  idea  of  a  solid  earth.  Others  have  used 
them  as  strong  evidence  of  a  thin  notation  crust  over  liquid  rock. 

But  a  "flotation  crust"  has  its  difficulties.  The  fact  that  there  are  high 
mountains  anywhere  is  one  of  them.  Against  this  objection  it  is  urged  that 


HYPOGEIC    WORK.  379 

mountains  may  have  great  cavities  beneath  them,  through  a  parting  and  open- 
ing in  the  crustal  terranes  underneath,  when  they  were  elevated ;  and  it  is 
stated  in  corroboration  that  by  means  of  the  plumb-line  it  is  proved  that 
the  Himalayas  have  not  the  density  of  a  solid  mass.  So  also  some  volcanic 
peaks  have  been  proved  by  pendulum  experiments  to  be  hollow.  If  volcanic 
mountains  generally  were  shells  over  a  cavity  that  was  emptied  in  making 
them,  the  fact  that  they  could  stand  on  a  thin  crust  would  be  no  marvel. 
But  the  pendulum  experiments  of  E.  D.  Preston  at  the  Hawaiian  islands 
have  shown  that  this  is  not  so.  He  found,  in  1892,  that  Haleakala,  on  east 
Maui,  10,000  feet  high,  has  a  density  of  2-7,  or  that  of  the  mass  of  rocks  at 
the  surface ;  and  that  Mount  Kea,  on  Hawaii,  nearly  14,000  feet  high,  while 
hollow  above,  —  the  density  there  being  only  2-1,  —  has  a  density  below  of 
3-7  (page  290).  Yet  these  mountains  stand,  and,  no  doubt,  under  adjusted 
gravitational  pressure;  but  how  so,  if  on  a  thin  crust,  is  an  unsolved 
mystery. 

Isostasy  is  earth-shaping  in  its  action,  without  being  mountain-making. 
It  has  been  in  all  time  conservative  of  existing  conditions  of  equilibrium. 
Subsidences  made  by  loads  have  caused  elevations  somewhere  around  the 
subsided  region;  but  the  mean  level,  according  to  the  principle,  must  have 
been  retained.  Loads  over  the  bed  of  a  Mexican  Gulf  should  cause,  in 
accordance  with  it,  a  subsiding,  but  not  a  deepening,  for  the  subsidence  just 
equals  the  load  ;  and  on  the  border  of  the  ocean  they  should  cause  a  subsid- 
ing of  the  coast  region,  and  not  a  sinking;  for  the  subsiding  could  not 
exceed  the  filling  contributed. 

The  ice  of  the  Glacial  period,  which  covered  a  large  part  of  northern 
North  America  and  Europe  to  a  depth  of  one  or  more  thousand  feet,  was  a 
load  laid  over  the  surface  by  moist  aerial  currents ;  and  to  this  load  has  been 
attributed  by  Jamieson  (1865),  Warren  Upham,  and  others,  the  succeeding 
subsidence  of  the  same  glaciated  regions,  or  that  of  the  Champlain  period. 
(See  further,  page  1020). 

3.  Continental  plateaus  and  oceanic  depressions.  —  According  to  the  prin- 
ciple of  gravitational  equilibrium,  the  earth's  greater  unevenness  of  surface, 
exhibited  in  the  existence  of  oceanic  depressions  and  continental  plateaus, 
should  be  an  expression  of  some  difference  in  the  density  of  the  rocks. 
Perhaps  the  fact  that  the  prevailing  rocks  of  the  oceanic  volcanoes  are 
basaltic,  and  of  the  continental,  andesytic  and  trachytic,  explains  how  it  is 
that  the  oceanic  crust  is  made  the  denser.  The  difference  in  the  mean  den- 
sities of  the  basaltic  and  andesytic  rocks  is  about  one  tenth.  The  depres- 
sions, on  this  view,  were  made  in  the  earth's  cooling. 

This  origin  of  the  oceanic  basins  was  suggested  in  1860  by  Archdeacon  J.  H.  Pratt,  in 
his  memoir  on  the  Figure  of  the  Earth,  where  he  attributes  the  existence  of  continents 
and  these  basins  to  unequal  contraction,  refers  the  formation  of  mountains  to  lateral 
pressure,  and  concludes  that  "  the  crust  beneath  the  oceans  is  of  greater  density  than  the 
average  portions  of  the  surface"  ;  that  is,  that  where  the  contraction  was  greatest  the 
density  of  the  rock  material  below  is  greatest,  and  proportionally  so. 


380  DYNAMICAL   GEOLOGY. 

Since  the  mean  height  of  the  present  continents  is  about  2000  feet,  and 
the  mean  depth  of  the  oceans  12,000  feet,  and  since  the  continental  areas 
were  already  outlined  and  partly  emerged,  during  later  Archaean  time,  this 
mean  depth  of  the  oceanic  depressions  must  also  have  been  then  acquired; 
and  only  an  addition  of  1500  to  2000  feet  was  needed  to  give  the  continents 
their  present  mean  altitude.  Of  this,  more  than  one  half  was  added  in  the 
Tertiary  and  Quaternary. 

2.    OROGENIC  WORK,  OR  THE  MAKING  OF  MOUNTAINS. 

1.  In  ordinary  mountain-making,  the  rock  material  to  be  made  into  the 
mountain  range  has  comprised  a  thick,  conformable  series  of  sedimentary 
strata,  resting  upon  an  uneven  floor  of  upturned  and  usually  crystalline 
rocks  which  were  part  of  the  underlying  earth's  crust.  The  Appalachian 
and  Laramide  strata  were  laid  down  on  an  Archaean  floor;  the  Palisade 
beds  of  the  Triassic,  from  New  York  southwestward,  on  one  that  was 
partly  Archaean  and  partly  consisted  of  Archaean  and  Cambro-Silurian  ter^ 
ranes  combined. 

The  great  facts  to  be  explained  in  a  theory  of  mountain-making  relate 
(1)  to  the  preparatory  geosyncline  or  trough  and  its  load  of  strata  for  the 
mountain  structure ;  (2)  to  the  mountain-making  events  ;  the  upturning, 
flexing,  and  faulting  of  the  strata,  and  all  other  effects  of  the  movements 
in  progress.  On  any  theory  of  origin,  such  mountain  ranges  are  syndinoria, 
as  they  have  been  termed  by  the  author,  from  the  Greek  for  syndine,  and 
opos,  mountain,  —  they  having  had  their  beginning,  as  first  recognized  by  Hall, 
in  a  preparatory  geosyncline  of  accumulation.  The  geosyncline  occupied  the 
area  of  the  future  mountain  range.  It  was  slowly  formed,  while  the  crisis 
of  upturning  was  relatively  short.  For  the  Appalachians  the  geosyncline, 
judging  from  the  thickness  of  the  included  beds,  had  a  maximum  depth  of 
40,000  feet;  for  the  Laramide  Kange,  north  of  Montana,  34,000  feet  (Mc- 
Connell)  and  for  the  Wasatch  portion,  31,000  feet  (C.  King)  ;  for  the  Alps, 
at  the  close  of  the  Miocene,  50,000  feet  (Heim) ;  for  the  Australian  Alps, 
35,000  feet  (Hector)  ;  for  the  Palisade  ranges,  3000  to  5000  feet. 

The  subsidence  in  the  case  of  the  Appalachian  Range  occupied  all  of 
Paleozoic  time ;  of  the  Wasatch  Range  and  other  ranges  of  the  Laramide 
system,  all  of  Paleozoic  and  Mesozoic  time, — which  means  many  millions 
of  years  for  each.  Again,  there  is  the  remarkable  fact  that  the  subsidence 
has  not  always  been  continuous,  but  sometimes  alternated  with  emergences, 
or  ceased  for  long  periods.  In  the  case  of  the  Ouachita  Mountains,  Arkan^ 
sas,  whose  history  runs  parallel  with  that  of  the  Appalachians,  there  was  a 
cessation  through  the  whole  of  the  Upper  Silurian  and  Devonian,  for  these 
eras  are  unrepresented  by  rocks.  Moreover,  the  area  of  the  geosyncline,  as 
the  deposits  show,  varied,  as  the  ages  passed,  in  width ;  varied  in  the  posi- 
tion of  the  belt  of  maximum  subsidence,  from  one  side  to  the  other,  or 
from  one  part  to  another ;  varied  in  the  depth  of  water  in  which  the  deposits 


HYPOGEIC   WORK.  381 

were  made,  and  in  the  courses  and  character  of  the  transporting  currents 
and  waves. 

Further,  the  making  of  the  geosyncline  must  have  been  attended  in  each 
case  by  a  pushing  aside  of  the  rock  material  in  the  earth's  mass  existing 
beneath  it,  and  an  upward  bulging,  or  a  geanticline,  over  the  region  adjoining 
on  one  side  or  the  other. 

The  more  prominent  theories  of  mountain-making  now  current  are  (1)  the 
Gravitation  Theory  and  (2)  the  Contraction  Theory. 

1.   The  Gravitation  Theory. 

The  Gravitation  Theory  was  brought  forward  in  its  simplest  form  by 
James  Hall  in  1859.  According  to  it,  the  making  of  the  preparatory  geosyn- 
cline, in  the  case  of  the  Appalachians,  was  due  to  the  gravitation  of  the 
accumulating  sediments,  in  accordance  with  the  principle  explained  by  Her- 
schel,  whose  views  he  cites  ;  and  the  making  of  the  flexures  over  the  region 
was  due  to  the  same  cause ;  that  is,  to  the  subsidence  and  not  to  heating 
from  below.  In  the  same  paper,  the  general  conclusion  already  referred  to 
is  drawn  that  a  geosyncline  of  accumulation,  like  that  of  the  Appalachians, 
is  a  necessary  preliminary  in  all  cases  of  mountain-making.  In  1847,  Bab- 
bage  published  the  important  principle  (included  in  a  paper  read  before  the 
Geological  Society  of  London  in  1834)  that  in  deepening  accumulations  of 
sediments,  heat  rises  from  below  into  the  pile  as  its  depth  increases,  as  ex- 
plained on  page  258,  and  that  the  subterranean  heat  causes  changes  of  level 
through  the  expansion  and  contraction  of  the  rocks. 

T.  Mellard  Reade,  after  a  study  of  the  expansion  of  heated  rocks  of  dif- 
ferent kinds,  adopting  the  views  of  Herschel  and  Babbage,  attributes  flexures, 
and  other  effects  attending  mountain-making,  not  merely  to  the  heat  from 
below  indicated  by  the  rising  isogeothermals,  but  also  to  additional  heat  at 
intervals  from  a  succession  of  intrusions  of  igneous  rocks  consequent  on  the 
conditions.  He  styles  his  theory  "the  origin  of  mountain  ranges  by  sedi- 
mentary loading  and  cumulative  recurrent  expansion," — recurrent  because 
of  the  successive  igneous  intrusions.  He  found  for  the  rate  of  expansion  of 
average  rock  2-75  lineal  feet  per  mile  for  every  rise  of  100°  F.  The  igneous 
intrusions  are  said  to  occur  generally  along  the  axis  or  axes  of  the  range  in 
process  of  construction. 

The  principle  that  loading  causes  subsidence  of  the  crust  has  been  supplemented  by  C. 
King  (1876)  with  its  apparent  complement  that  unloading  by  denudation  causes  elevation, 
—  he  holding  at  the  same  time  that  these  effects  take  place  in  a  solid  globe.  The  elevation 
of  the  Rocky  Mountain  area,  during  Tertiary  time,  is  accordingly  attributed  by  him  to  the 
removal,  through  denudation,  of  a  vast  amount  of  material  from  the  vicinity  of  the  Colorado 
canon,  and  from  other  parts  of  the  mountains. 

With  regard  to  the  view  of  King,  and  especially  this  example  under  it,  Le  Conte  has 
observed  that  the  weight  of  the  rock  material  elevated  in  the  rise  of  the  great  mountain 
area  to  a  height  of  4000  to  11,000  feet  was  vastly  larger  than  the  amount  lost  by  denuda- 


382  DYNAMICAL   GEOLOGY. 

tion,  and  adds  that  the  denudation  could  not  have  produced  any  result  until  the  elevation 
had  made  some  progress.  The  theory  supposes  the  isostatic  condition  of  the  globe ;  and  if 
this  was  the  condition  in  Cretaceous  time  before  the  elevation  began,  the  elevation  never 
could  have  taken  place  without  force  from  some  real  source. 

In  accordance  with  the  above,  the  evaporation  of  the  flooded  Great  Salt  Lake  (called 
Lake  Bonne ville),  which,  in  the  middle  of  the  Quaternary  era,  had  reached  a  depth  of 
1000  feet,  has  been  suggested  by  G.  K.  Gilbert  as  the  cause  of  the  inequality  of  height  in 
different  parts  of  the  terrace  that  marks  its  old  coast-line.  The  change  of  level  indicated 
is  stated  to  be  about  200  feet.  The  pressure  of  1000  feet  of  water,  or  that  removed  by 
evaporation,  is  equivalent  to  450  pounds  to  the  square  inch.  The  theory  implies  a  molec- 
ular transfer  (as  the  waters  disappeared  in  the  Middle  Quaternary)  from  the  outside 
region  to  that  beneath  the  lake.  The  explanation  is  put  forward  by  Gilbert  with  the 
statement  that  further  investigation  is  required  before  the  view  can  be  regarded  as  estab- 
lished. 

The  difficulty  with  the  Gravitation  Theory  in  its  best  form  is  that  it  does 
not  supply  the  amount  of  pressure,  and  of  contraction  or  expansion,  which  is 
required  by  the  facts. 

This  is  true  of  Reade's  theory,  even  with  the  recurrent  work  of  igneous 
intrusions.  In  the  case  of  the  Appalachians  the  width  of  the  geosyncline 
from  S.E.  to  N.W.  is  less  than  250  miles.  The  ratio  of  maximum  depth 
to  width  is  about  1  to  40,  or  that  of  a  trough  as  wide  as  this  printed  page 
and  one  ninth  of  an  inch  deep.  The  depth  of  the  strata,  40,000  feet,  gives 
for  the  temperature  at  the  bottom  of  the  geosyncline  (supposing  the  rate  of 
downward  increase  to  be  1°  F.  for  each  50  feet  of  descent)  800°  F.  Conse- 
quently an  expansion  of  2-75  feet  for  250  miles  of  width  and  for  each  100° 
F.  amounts  to  5500  feet,  or  a  little  over  a  mile.  Lesley  makes  the  actual 
shortening  over  the  breadth  of  the  geosyncline  in  Pennsylvania,  in  con- 
sequence of  the  flexures,  to  be  44  miles,  and  Claypole  88  miles.  The  dis- 
crepancy is  too  large  to  be  removed  by  questioning  either  estimate.  Many 
of  the  single  folds  would  use  up  several  times  the  5500  feet.  So  it  is  in 
other  cases. 

In  the  Laramide  Kange,  of  southern  British  America,  a  thickness  of  the  rocks  in  the 
geosyncline  of  34,000  feet,  and  the  width  of  the  trough  about  150  miles,  give  for  the  tem- 
perature of  the  bottom  about  700°  F.  ;  and  the  expansion,  under  these  conditions,  would 
be  only  2900  feet  for  the  whole  width.  The  displacement  horizontally  of  one  of  the 
several  faults,  according  to  McConnell,  is  7  miles,  or  nearly  13  times  the  maximum 
allowed  for  the  range  by  the  theory  under  consideration.  In  the  Juras,  Heim  found  the 
contraction  by  flexures  to  be  3  miles,  or  one  fourth,  for  the  distance  between  Lake  Geneva 
and  Saint  Claude  ;  and  in  the  eastern  Jura  to  be  4  miles  in  a  breadth  of  7  miles. 

There  is  the  further  objection  to  the  theory  that  in  a  trough,  having  the 
depth  only  a  thirtieth  or  a  fortieth  of  the  breadth,  the  expansion  would  act 
nearly  equally  in  all  directions;  so  that  while  longitudinal  ridges  might 
prevail,  transverse  should  be  common  instead  of  uncommon.  But  the  ex- 
panding effects  from  the  heat  of  successive  igneous  intrusions  are  to  be 
added,  according  to  the  theory,  ridges  thus  succeeding  ridges.  In  the  case 
of  the  Appalachians,  there  were  no  igneous  intrusions  along  the  chief  part 


HYPOGEIC   WORK.  383 

of  the  axis  of  disturbance,  and  none  in  the  Laramide  Eange  of  British 
America,  and  the  same  is  true  in  a  large  part  of  mountain-making.  In  the 
Wasatch  the  igneous  effusions  were  a  final  effect,  not  an  agent  of  change. 

Moreover,  the  pressure  from  any  igneous  intrusions,  or  their  power  of  com- 
pression, is  feeble.  Plastic  rock  is  little  better  for  pressure  than  any  pasty 
material ;  when  extruded  it  is  hurried  out  of  the  way  by  the  compression  of 
any  other  agent,  or  escapes,  if  it  can,  by  gravity.  When  it  cannot  escape,  it 
bulges  up  the  overlying  beds  and  makes  laccoliths  (page  301),  and  this  is 
almost  its  limit  of  mechanical  work.  The  heat  also  is  wholly  inadequate 
for  plicating  and  faulting  rocks  in  mountain-making  style,  whether  the  liquid 
rock  be  granitic  or  of  any  other  constitution ;  the  laws  as  to  heating  and 
cooling  are  the  same  for  all  kinds. 

2.   The  Contraction  Theory. 

1.  TJie  source  of  lateral  pressure.  —  The  source  of  the  pressure  accord- 
ing to  the  contraction  theory  is  the  contraction  of  the  earth's  crust  as  a  con- 
sequence of  cooling.  The  theory  was  suggested  by  Descartes  in  his  Principia 
Philosophice  in  1644,  and  by  Newton  in  1681,  and  was  adopted  in  geology 
by  James  Hall,  of  Edinburgh,  in  1812,  and  advocated  by  De  La  Beche 
in  1834.  The  contracting  crust  derives  the  lateral  pressure  from  the  cooling 
and  solidification  that  is  going  on  underneath  it  —  the  crust  being  forced 
to  adapt  itself  to  an  interior  which  is  becoming  smaller  by  the  earth's 
gradual  refrigeration.  Mountain-making,  according  to  the  theory,  is  a  con- 
sequence largely  of  the  earth's  shrinkage. 

The  author's  contributions  to  the  subject,  including  also  that  of  the  Origin  of  Con- 
tinents and  their  Features,  appeared  first  in  the  years  1846,  1847  and  1849,  and  were 
continued  in  1856  and  1873.  The  development  of  the  structure  of  the  Appalachians 
through  Virginia  and  Pennsylvania  by  the  Professors  Rogers  afforded  the  first  geological 
demonstration  in  favor  of  the  contraction  theory  ;  and  the  results  they  published,  although 
leading  the  investigators  at  the  time  to  a  theory  based  on  forced  movements  in  the 
earth's  liquid  interior,  underneath  a  thin  crust,  afforded  the  author  illustrations  of  the 
views  in  his  early  papers. 

Since  the  earth  has  oceanic  basins  and  continents  of  diverse  dimensions 
and  features,  this  lateral  pressure  would  work  with  direct  reference  to  conti- 
nental lines,  and  generally  have  its  shoving  and  relatively  resisting  sides  in 
epochs  of  orographic  work.  If  the  pressure  acted  thus  unequally  from  the 
two  opposite  directions,  it  would  make  inequilateral  mountain  structures,  or 
those  having  a  front-and-rear  character,  like  the  Appalachian  Range. 

Moreover,  the  movements  would  have  their  limits  determined  by,  or  re- 
lated to,  the  lengths  of  continents,  or  great  continental  regions,  and,  in  this 
respect,  they  accord  with  the  actual  characters  of  mountain  chains.  The 
Laramide  system,  over  4000  miles  in  length,  along  the  western  continental 
border  of  North  America,  is  an  example  ;  and  perhaps  another  4000  miles 


384  DYNAMICAL   GEOLOGY. 

along  a  line  farther  west  should  be  added  for  South  America.     The  agent 
for  such  results  must  be  the  earth  in  its  entirety. 

2.  Location  of  the  lateral  pressure.  —  The  surface  layer  of  the  globe 
in  which  the  pressure  acts  has  recently  been  shown  to  be  thin.  In  the 
cooling  and  contraction  of  the  crust,  the  lower  part  of  the  cooled  portion, 
enveloping  the  uncooled  nucleus  that  had  not  begun  to  lose  its  heat  or 
contract,  could  not  contract  without  breaking,  and,  therefore,  the  cooling 
would  put  it  into  a  state  of  tension,  which  would  result  in  the  opening  of 
fractures.  For  if  a  layer  undergoing  contraction  is  united  to  a  non-contract- 
ing or  less-contracting  layer,  the  contraction  would  necessarily  produce  ten- 
sion and  fractures.  Thus  the  cooling  crust  must  be  made  up  of  an  inner 
portion  in  a  state  of  tension  and  an  outer  in  a  state  of  lateral  pressure,  and 
the  two  portions  are  separated  by  a  level  of  no  strain.  The  outer  is  the 
effective  part  in  orogeny.  The  lateral  pressure  within  it  is  greatest  at  the 
surface,  and  diminishes  downward.  The  thickness  of  the  effective  layer 
depends  on  the  length  of  the  time  that  has  elapsed  since  the  solidification  of 
the  earth  at  surface  —  the  time  when  the  strain  was  initiated.  It  was  esti- 
mated by  Mellard  Eeade  as  only  two  miles  (1886).  It  has  been  mathemati- 
cally discussed  first  by  C.  Davison,  and  afterward  by  G.  H.  Darwin  and  M.  P. 
Rudski,  who  sustain  the  contraction  theory  of  mountain-making.  Davison 
made  the  thickness  (1887,  '89)  2-17  miles,  supposing  the  elapsed  time  to  be 
100,000,000  years;  and  Darwin  (1887),  two  miles,  for  the  same  elapsed  time, 
adding  that  "the  depth  is  proportional  to  the  time  since  consolidation." 
Davison,  in  a  later  "calculation  (1894)  based  on  the  supposition  that  the 
coefficient  of  dilatation  is  not  constant,  as  he  before  had  assumed,  but 
increases  with  the  temperature,"  arrives  at  the  more  favorable  conclusion 
that,  after  100,000,000  years,  "the  depth  of  the  surface  of  zero-strain 
would  be  7-79  miles."  He  says  further,  that  "if  the  material  of  the 
earth's  interior  be  such  that  the  conductivity  and  coefficient  of  dilatation 
are  greater  in  it  than  in  the  surface  rocks,  or  if  initially  the  temperature 
increased  with  the  depth,  the  above  figure  must  be  still  further  increased  "  ; 
and  adds,  in  conclusion,  "that,  consequently,  calculations  as  to  the  alleged 
insufficiency  of  the  contraction  theory  to  produce  mountain-ranges  are  at 
present  inadmissible."  It  is  therefore  safe  to  assume,  in  view  of  the 
dependence  of  mountain  plications  on  lateral  pressure,  that  the  thick- 
ness was  fully  sufficient  for  the  orographic  results ;  and  even  in  late 
Archaean  time  great  enough  to  make  Archaean  mountains  of  8000  to  10,000 
feet,  such  as  the  Adirondack  and  Black  Mountains  must  have  been  before 
subjected  to  denudation. 

Darwin  states  at  the  close  of  his  paper  (which  follows  Davison's  in  the  Philosophical 
Transactions),  after  deducing  that  contraction  vanishes  at  a  depth  of  2  or  3  miles :  "  Thus, 
in  10,000,000  years,  228,000  square  miles  of  rock  will  be  crumpled  on  the  top  of  subjacent 
rocks.  The  numerical  data  with  which  we  have  to  deal  are  all  of  them  subject  to  wide 
limits  of  uncertainty,  but  the  result  just  found,  although  rather  small  in  amount,  is 
Such  as  to  appear  of  the  same  order  of  magnitude  as  the  crumpling  observed  geologically. 


HYPOGEIC   WORK.  385 

The  stretching  and  probable  fracture  of  the  strata  at  some  miles  below  the  surface  will 
have  allowed  the  injection  of  the  lower  rocks  amongst  the  upper  ones,  and  the  phenomena, 
which  we  should  expect  to  find  according  to  Mr.  Davison's  theory,  are  eminently  in 
accordance  with  observation.  It  therefore  appears  to  me  that  his  view  has  a  strong 
claim  to  acceptance." 

Further,  Mr.  Darwin  cited,  in  1892,  the  recent  calculations  of  Rudski  of  Odessa, 
which  showed  that  if  the  initial  temperature  of  the  sphere  be  not  uniform  through  the 
mass,  that  is,  if,  as  in  the  case  of  the  earth,  the  initial  temperature  increased  from  the 
surface  to  the  center,  the  level  of  no  strain  lies  deeper  than  he  had  made  it.  As  to  the 
actual  depth  thus  indicated  he  made  no  statement.  (Phil.  Mag.,  Sept.,  1892.) 

3.  Tlie  process  of  mountain-making  according  to  the  Contraction  Theory.  — 
The  making  of  the  preparatory  geosyncline,  with  its  included  series  of  strata, 
was  slow  in  its  progress.  As  it  included,  in  the  case  of  the  Appalachians, 
all  of  Paleozoic  time  to  the  close  of  the  Carboniferous,  the  rate  of  subsidence 
—  the  depth  being  40,000  feet  —  was,  if  the  time  was  40,000,000  years,  about 
1  foot  in  1000  years  ;  if  10,000,000  years,  1  foot  in  250  years.  The  rate,  on 
either  supposition  as  to  the  elapsed  time,  was  so  slow  that  the  subsidence  may 
have  been  a  result  of  the  loading  of  the  area  with  the  sediments.  Yet  it  can- 
not be  asserted  that  lateral  pressure  in  the  crust  was  not  concerned  ;  for  if  it 
was  the  prime  cause  of  movements  at  the  crisis,  it  could  hardly  have  been 
dormant  through  the  long  preceding  ages  when  the  trough  was  in  progress. 
The  subsidence  went  forward,  so  far  as  can  be  discovered,  without  much  dis- 
placement of  the  beds  within  them,  beyond  such  as  were  due  to  unequal 
compression  by  gravitation,  drying,  and  some  solidification.  The  pile  of 
beds  had  great  breadth  as  compared  with  its  depth,  and  varied  much  in  thick- 
ness, owing  to  irregularities  in  the  Archaean  floor  beneath,  and  to  varying 
rates  in  the  progress  of  the  subsidence.  Limestones  indicate  much  slower 
movement  downward  than  coarse  sediments  of  like  thickness ;  and  inter- 
calated beds  of  coal  prove  that  long  periods  of  slight  emergence  were  among 
the  alternations. 

When  the  mountain-making  crisis  was  at  hand,  the  temperature  at  the 
bottom  of  the  deposits  was  already  high  from  the  rise  of  the  geothermals 
with  the  increase  of  thickness.  With  a  thickness  of  40,000  feet,  and  the  rate 
of  increase  of  temperature  downward  1°  F.  in  50  feet,  it  would  be  800°  F. 
But  the  rate  was  probably  as  rapid  as  1°  F.  in  40  feet  or  less,  making  the 
temperature  at  bottom  1000°  F.  or  higher.  At  either  temperature  the  trough 
would  have  been  greatly  weakened  below,  as  first  explained  by  Herschel.  In 
a  letter  addressed  to  Lyell,  dated  February,  1836,  and  in  another  to  Murchi- 
son,  dated  November,  1836,  which  are  published  in  the  Appendix  to  Bab- 
bage's  Ninth  Bridgewater  Treatise  (1837),  he  presents,  besides  the  view  that 
heat  will  rise  from  below  into  an  accumulating  series  of  strata,  as  had  been 
done  by  Babbage,  the  suggestion  that  "  the  thicker  the  deposit,  the  hotter 
will  its  lower  portions  tend  to  grow,  and  if  thick  enough  they  may  grow  red- 
hot,  or  even  melt.  In  the  latter  case,  their  supports,  being  also  melted  or 
softened,  may  wholly  or  partially  yield  under  the  new  circumstances  of  pres- 
D  ANA'S  MANUAL  —  25 


DYNAMICAL  GEOLOGY. 

sure,  to  which  they  were  originally  not  adjusted;  and  the  phenomena  of 
earthquakes,  volcanic  explosions,  etc.,  may  arrive."  These  results  are 
favored  by  the  fact  that  the  deposits  were  not  half  consolidated,  and,  there- 
fore, little  able  to  resist  the  pressure. 

In  the  consequent  collapse  from  the  continued  pressure,  the  included 
strata  would  be  necessarily  shoved  up  out  of  place,  flexed  in  anticlines  and 
synclines,  and  traversed  by  great  oblique  fractures,  as  Daubree's  experiments 
illustrate,  which  would  become  the  courses  of  displacements,  all  on  a  scale 
of  magnitude  comporting  with  the  thickness  of  the  accumulated  formations. 
The  flexures  were  not  flexures  of  the  earth's  crust,  but  of  the  supercrust,  or 
the  beds  in  the  geosyncline.  The  work  was  slow  in  progress ;  for  the  great 
flexures  in  such  mountain-making  are  produced  without  obliterating  or  seri- 
ously obscuring  the  stratification. 

In  the  great  forced  movement,  if  the  pressure  on  the  two  sides  of  the 
trough  was  unequal,  as  was  commonly  the  fact,  the  beds  were  shoved  from 
the  side  of  strongest  pressure,  or  thrust,  toward  the  opposite.  Consequently 
the  flexures  became  crowded  and  steepest  on  the  former  side,  and  the  over- 
thrust  flexures  and  upthrust  blocks  were  thrust  toward  the  other  side. 
Hence  the  resulting  mountain  range  and  its  flexures  are  inequilateral.  In 
the  case  of  the  Appalachians,  the  thrust  was  strongest  on  the  side  toward 
the  ocean.  Further :  on  the  side  of  least  pressure,  the  mountain  range 
often  declines  into  elevated  plateaus,  with  feebly  undulating  or  horizontal 
stratification,  as  exemplified,  on  the  landward  side  of  the  Appalachians,  in 
the  Cumberland  plateau  and  its  continuation  northward;  in  the  Uinta 
Mountains  and  the  high  plateaus  of  Utah  on  the  landward  side,  and  to  the 
south,  of  the  Wasatch.  In  the  narrow  troughs  of  deposition  of  eastern 
North  America,  the  flexures  often  fail  to  indicate  inequilateral  pressure. 

After  a  mountain-birth  there  has  commonly  succeeded  a  time  of  relaxed 
lateral  pressure ;  and  then  occurred  adjustments,  largely  by  gravitation,  in 
the  moved  masses  or  faulted  blocks  making  chiefly  downthrow  displace- 
ments, besides  producing  new  fractures  and  faults.  Such  displacements 
have  taken  place  especially  in  the  region  of  mountain  plateaus,  where  the 
pressure  was  least. 

Illustrations  of  the  steps  in  the  contraction  process  of  mountain-making 
have  been  above  derived  mostly  from  the  Appalachian  Range.  They  may 
be  found  almost  equally  apposite  in  most  of  the  mountains  of  the  world,  as 
the  examples  already  given  prove.  The  Taconic  Range,  on  the  borders 
between  New  England,  and  New  York  and  Canada,  has  the  same  general 
characteristics  as  the  Appalachian,  with  the  addition  of  the  universal  meta- 
morphism  of  the  beds  of  sandstone,  shale,  and  limestone.  Its  preparatory 
geosyncline  was  on  a  parallel  line  with  the  northern  part  of  the  Appala- 
chian; and  the  two  were  deepening  and  taking  in  deposits  together  until 
the  close  of  the  Lower  Silurian,  when  the  Taconic  mountain-making  crisis 
came.  The  rocks  of  the  range  are,  therefore,  only  those  of  the  Cambrian  and 
Lower  Silurian.  It  is  probable  that  this  mountain  belt  extends  through 


HYPOGEIC   WORK.  387 

Virginia  southwestward,  along  a  series  of  Taconic  geosynclines  that  ended 
in  the  making  of  a  series  of  Taconic  ranges,  on  a  line  east  of  the  Appala- 
chian Range.  See  further,  pages  531,  532. 

4.  Geanticlines  corresponding  to  the  geosynclines.  —  It  is  not  always  easy 
to  identify  the  one  or  more  geanticlines  that  the  sinking  of  a  geosyncline  may 
have  produced.     In  the  case  of  the  Taconic  and  Appalachian  ranges  little 
doubt  exists.     When  the  Taconic  Range  was  completed,  already  a  low  geanti- 
cline had  risen  above  the  continental  sea,  making  two  large  islands  between 
southern  Ohio  and  Alabama,  one  over  the  region  of  Cincinnati  and  part  of 
Kentucky,  and  the  other  in  the  same  line  over  Tennessee.      The  region, 
often  called  that  of  the  Cincinnati  uplift,  was  first  identified  as  a  Middle 
Silurian  emergence  by  J.  S.  Newberry  and  J.  M.  Safford.     Moreover,  an 
eastern  geanticline  also  showed  itself ;  for  the  whole  Atlantic  border  from 
New  York  southwestward  through  Virginia  and  beyond  became  emerged  at 
the  same  time,  and  continued  so,  with  probably  increasing  height  through 
the  Upper  Silurian,  Devonian,  and  Carboniferous  eras,  when  the  making  of 
the  Appalachian  Range  took  place ;  and  also  after  this,  through  the  Triassic 
and  Jurassic  periods  until  the  Middle  Cretaceous ;  for  through  all  this  time 
no  beds  with  marine  fossils  were  formed  over  this  great  area. 

The  contraction  theory  of  mountain-making,  as  is  seen,  appeals  to  an  all- 
pervading  force  that  must  have  been  at  work  from  the  time  the  earth  first 
had  a  solid  exterior.  Already  in  later  Archaean  time  it  had  made  Archaean 
mountain  ranges ;  and  it  is  manifest,  from  succeeding  events,  that  through- 
out all  time  one  system  of  evolution  was  in  progress.  Moreover,  the  theory 
has  the  virtue  of  explaining  the  facts,  which  is  not  true  of  the  gravitation 
theory.  No  other  adequate  explanation  has  been  proposed.  If  the  calcula- 
tions of  physicists  do  not  give  a  sufficient  depth  for  the  results  to  the  "  level 
of  no  strain/'  then  the  calculations  may  be  believed  to  be  in  error  until 
some  other  adequate  cause  of  the  great  faults  and  flexures  has  been  brought 
forward. 

5.  Relations  of  mountain  ranges  to  denudation.  —  Carving,  gouging,  and 
leveling  through  denudation  go  on  very  rapidly  in  elevated  regions  of  even  a 
moderate  amount  of  rain,  and  have  gone  on  through  long  ages  since  the  rocks 
were  made,  so  that  the  original  forms  of  the  anticlines  and  synclines  of 
mountain  ranges  have  disappeared,  generally  leaving  ridges  where  synclines 
once  existed. 

Yet  the  geologist  may  still  have  little  difficulty  in  tracing  out  the  plica- 
tions, even  if  the  region  over  which  they  extend  is  now  a  level  plain.  The 
investigator  looks  for  evidence  of  folds  in  change  of  dip.  If,  on  his  way 
westward  over  a  region,  he  finds  eastward  dips  changed  to  westward,  he  has 
passed  the  axis  of  an  anticline ;  and  if,  going  farther,  he  finds  westward  dips 
changed  to  eastward,  he  sees  proof  that  he  has  reached  the  axis  of  a  syn- 
cline.  Complexities  are  added  by  the  great  faults,  making  difficulties  which 
can  hardly  be  surmounted  without  the  aid  of  fossils. 

From  the  facts  presented  in  the  above  review  of  the  structure  of  moun- 


388  DYNAMICAL  GEOLOGY. 

tain  ranges,  the  reasons  for  the  directions  of  drainage  courses  over  such 
regions  are  easily  understood.  The  prevailing  courses  are  longitudinal  as 
regards  the  range ;  not  because  synclinal  troughs  are  longitudinal,  for  these, 
in  the  case  of  bold  flexures,  are  not  ordinarily  the  courses  of  river  valleys ; 
but  for  the  more  general  reason  that  the  flexures  and  faults  in  the  range  are 
longitudinal.  The  greater  valleys  are  made  along  anticlines,  because  of 
the  profound  longitudinal  fracturing  of  their  summits,  in  consequence  of 
the  tension  produced  by  the  upward  bending  of  the  strata.  This  leaves  the 
intervening  synclinal  belt  as  the  course  of  the  mountain  ridges.  Besides, 
the  synclinal  strata  come  under  extreme  pressure  during  the  flexing  process, 
and  may  have  derived  by  this  means  greater  durability.  If  the  rocks  of  the 
range  are  crystalline  schists  and  limestone,  the  limestone  yields  easily  to 
denudation,  and  would  determine  in  general  the  course  of  the  drainage 
channel.  But  among  uncrystalline  rocks,  limestone  is  harder  than  shale  and 
some  sandstone. 

It  has  been  stated  that  in  a  region  of  upturned  rocks,  as  that  of  the 
Appalachian  Range,  the  flexures  are  made  in  series  along  a  few  parallel 
lines,  and  sometimes  in  a  succession  of  groups  ;  and  consequently  that  those 
of  different  lines  often  overlap  at  their  extremities.  Hence,  along  these 
intervening  or  overlapping  portions  the  strata  are  irregularly  warped  and 
fractured,  and  thus  weakened.  Here,  consequently,  erosion  should  be  easy, 
and  transverse  or  oblique  courses  of  drainage  would  result. 

Great  mountain  ranges  and  systems  have  been  shown  to  have  one  or 
more  curves  in  their  courses.  The  Appalachian  Range,  for  example,  changes 
from  its  south-by-west  course  in  New  York  to  west-southwest  in  Pennsyl- 
vania, and  then  leaves  this  state  with  a  south-southwest  course,  which  to  the 
southward  veers  again  to  west-southwest.  Here  is  another  cause  for  trans- 
verse lines  of  drainage ;  for  such  a  range  usually  diminishes  in  height  over 
its  more  nearly  meridional  or  more  latitudinal  part.  In  the  Appalachians 
the  lower  part  is  along  the  latter ;  and  here,  as  Lesley's  map  of  Pennsyl- 
vania shows  (page  730),  the  range  is  crossed  by  the  Susquehanna. 

Finally,  along  a  region  of  a  number  of  close-pressed  folds,  having  great 
longitudinal  fractures  with  displacements,  a  drainage  valley  may  take  great 
width. 

If  the  plications  or  monoclines  over  an  extended  area  have  small  dip, 
then  the  broad  synclines  and  the  depression  between  monoclines  or  lines  of 
displacement  may  become  the  courses  of  streams. 

Epeirogenic  movements  that  give  a  height  of  many  thousands  of  feet  to 
large  continental  areas  add  these  thousands  to  the  elevation  of  the  moun- 
tain ranges  along  the  region;  and  hence,  besides  causing  flows  of  water  down 
the  gentle  slopes,  they  produce  a  vast  increase  of  precipitation  and  denuda- 
tion about  the  summits,  and  make  the  streams  great  rivers.  Over  the  in- 
terior of  continents  such  movements  may  cause  undulations  or  warpings 
of  the  surface,  which  occasionally  reverse  the  flow  of  rivers,  or  unite  inde- 
pendent river  systems  into  one,  or  make  depressions  that  become  the  basins 
of  lakes. 


HYPOGEIC   WORK.  389 

6.  Ranges,  Systems,  Chains,  Cordilleras  in  North  America. — From  the 
explanations  given  it  is  apparent  that  a  mountain  range  includes  all  the 
mountain  ridges  made  over  the  area  and  border  of  a  single  geanticline.  The 
Appalachian  is  an  example  900  miles  long ;  it  comprises  many  ridges,  but 
these  are  made  by  denudation.  Ranges  are  the  individuals  or  units  in 
mountain  structures. 

A  mountain  system  includes  all  ranges  in  a  region  made  in  different,  more 
or  less  independent,  geosynclines  at  the  same  epoch.  Besides  the  birth  of 
the  Appalachian  Range  at  the  close  of  the  Carbonic  era,  there  was  also 
the  birth  of  an  Acadian  Eange,  from  Newfoundland  through  Nova  Scotia, 
and  probably  to  Ehode  Island.  Here  are  two  simultaneously  made  ranges 
on  the  Atlantic  border,  and  they  may  be  regarded  as  parts  of  an  Appalachian 
mountain  system.  Again,  in  western  Arkansas,  the  upturned  Paleozoic 
rocks  constitute  the  Ouachita  Mountain  range,  which,  as  L.  S.  Griswold  has 
suggested,  pertains  to  the  Appalachian  Mountain  system,  the  axis  of  uplift 
conforming  to  the  southern  portion  of  the  latter  in  Tennessee  and  Missis- 
sippi. As  another  example,  the  Wasatch  Mountains  constitute  one  of  the 
Laramide  ranges.  But  the  mountains  to  the  north  of  Montana,  in  British 
America,  described  on  pages  359-60,  were  evidently  made  over  another  trough 
in  the  same  line,  and  correspond  to  another  Laramide  range.  So  there  are 
others,  and  as  many  as  there  were  independent  or  partially  independent 
Laramide  troughs  along  this  line  in  the  Kocky  Mountains;  and  all  the 
mountain  ranges  originating  from  these  troughs  make  up  the  Laramide 
Mountain  system  of  North  America,  over  4000  miles  long. 

A  mountain  chain  is  a  combination  of  mountain  systems,  or  mountain 
belts  of  different  epochs.  On  the  Atlantic  side,  there  is,  along  the  Appalachian 
belt,  a  combination  consisting  of  the  Appalachian  system  of  post-Carbonifer- 
ous age,  the  Tacoriic  system  of  Middle  Silurian  age,  and  an  Archaean  system ; 
and  the  Palisade  mountain  system,  of  Jurassic  age,  may  be  added.  Together 
they  constitute  the  Appalachian  Chain. 

In  the  Rocky  Mountains,  the  main  Rocky  Mountain  Chain  of  British 
America,  which,  as  has  been  stated,  is  continued  southward  along  the 
Wasatch  Range,  includes  an  Archaean  system  and  the  Laramide  or  po'st- 
Cretaceous  system.  The  chain  is  not  continued  in  sight,  south  of  the 
Wasatch;  but  the  line  is  an  important  geological  boundary,  it  being  the 
western  limit  of  the  Cretaceous  formation,  and  the  eastern  of  the  Great 
Basin.  The  Front  Range  of  Colorado,  as  it  is  called,  is  the  course  of  another 
Archaean  system  and  also  of  other  Laramide  uplifts,  and,  therefore,  of  another 
summit  chain,  —  which  may  be  called  the  Colorado  Chain. 

Again,  nearer  the  coast,  the  mountain  belt  which  includes  the  Sierra 
Nevada  of  California,  the  Cascade  Range  of  Oregon  and  Washington,  the 
long  Coast  Range  of  British  Columbia,  as  it  is  called  by  G-.  M.  Dawson, 
together  with  the  range  to  the  south,  1000  to  nearly  5000  feet  high,  along 
the  California  peninsula,  are  parts  of  a  Sierra  chain,  combining  ranges  or 
systems  of  ranges,  of  Archaean  and  later  time.  In  like  manner  there  is  a 


390  DYNAMICAL  GEOLOGY. 

Coast  chain  commencing  to  the  south  in  the  Coast  ranges  of  California,  and 
continuing  along  the  islands  of  British  Columbia,  and  on  the  sea  border 
beyond  to  Mount  St.  Elias. 

Finally,  the  combination  of  two  or  more  chains  makes  a  Cordillera,  as 
the  term  is  used  in  South  America  for  the  Andes.  Accordingly,  the  Coast 
and  Sierra  chains  together  with  the  chains  of  the  Eocky  Mountain  summit 
constitute  the  Cordillera  of  the  Rocky  Mountains.  In  South  America  the 
term  cordillera  is  used  not  only  for  the  Andes  as  a  whole  but  often  also  for 
one  of  its  long  ridges  or  ranges  or  chains.  The  combined  mountain  systems 
of  the  whole  Pacific  border  of  North  America  were  first  called  a  Cordillera 
by  J.  D.  Whitney. 

By  the  above  definitions,  range,  system,  chain,  are  no  longer  interchange- 
able terms,  dependent  for  their  use  on  extent  or  complexity  of  mountain 
regions,  but  have  fixed  significations. 

Study  of  a  mountain  range.  —  Since  an  individual  mountain  range  has  great  magni- 
tude, and  commonly  great  complexity  through  its  long  series  of  involved  flexures  and 
faults,  and  through  the  excavating  work  of  running  waters,  investigation  requires  a  long 
and  searching  study  of  the  structure  as  a  whole,  —  that  is,  as  an  individual.  The  geological 
examination  of  a  single  ridge  of  a  range  may  afford  conclusions  as  to  the  fact  of  upturnings, 
flexures  and  faults  and  may  obtain  evidence  as  to  the  force  concerned,  and  perhaps  settle 
the  question  of  the  foliation,  or  bedding,  of  the  schists  of  the  ridge,  if  any  are  present.  But 
it  can  afford  no  general  conclusions  as  to  the  range  ;  and  a  petrological  investigation  would 
accomplish  still  less.  A  single  section  across  the  range  would  afford  facts,  but  no  general 
results ;  for  the  flexures  may  vary  every  few  miles,  new  faults  appear  and  other  rocks 
come  out  to  view.  The  student  should  make  his  sections  not  merely  in  one,  or  a  dozen 
transverse  lines,  but  in  as  many  lines  as  possible  in  all  directions,  studying  positions  of 
strata,  and  noting  the  changes  they  undergo  from  ridge  to  ridge  until  the  connection  of 
each  ridge  with  every  other  in  the  general  system  of  warping  has  been  ascertained. 
Further,  this  study  should  be  carried  on  until  the  true  limits  of  the  mountain  individual 
as  far  as  possible  are  ascertained.  And  if  the  range  is  more  or  less  metamorphic,  the  belt 
of  maximum  metamorphic  change  should  be  studied  out,  and  the  fringe  of  diminishing 
change,  on  one  or  both  sides.  A  ridge  of  upturned  rocks,  whether  Archaean  or  of  later 
date,  is  almost  invariably  evidence  of  the  existence,  in  the  region,  of  a  mountain  range  100 
to  1000  miles  long,  or  more  ;  and  this  should  be  assumed  to  be  a  fact  until  the  contrary  is 
proved. 

With  the  completion  of  the  investigation  there  will  be  little  further  reason  for  ques- 
tionings about  the  fact  of  pressure  and  movements  as  a  source  of  dynamical  effects  ;  and 
if  the  beds  are  metamorphic,  none  as  to  the  source  of  the  heat  that  produced  the  meta- 
morphism.  But  it  remains  for  petrology  to  complete  the  work  by  investigating  the  special 
characteristics  of  the  metamorphic  changes,  their  relations  to  the  positions  of  the  beds, 
the  minerals  due  to  the  original  metamorphism  and  the  results  of  later  changes,  besides 
other  points  in  the  history,  for  light  upon  which  geology  is  dependent  on  its  kindred 
science. 

Further,  a  mountain  range  being  a  very  large  individual,  —  a  length  of  a  thousand 
miles  and  breadth  of  more  than  a  hundred  being  common, — three  such  individuals 
cannot  exist  on  a  single  area  of  50  miles  square.  When,  therefore,  indications  of  three 
or  more  periods  of  upturned  rocks  are  announced,  as  indicated,  by  unconformabilities 
in  any  limited  region  of  upturned  crystalline  or  uncrystalline  rocks,  Archaean,  or 
others,  it  is  quite  certain  that  the  unconformabilities  are  in  part  only  unconformities 
through  faults,  or  overlaps,  or  erosion,  which  have  little  epochal  significance. 


HYPOGEIC   WORK.  391 

In  addition,  it  should  be  remembered  that  the  unconformabilities  between  the  upturned 
rocks  of  a  mountain  and  those  underlying  are  usually  confined  to  the  mountain  region. 
A  score  or  so  of  miles  to  one  side,  the  rocks  may  often  be  found  resting  beneath  the  same 
strata,  perhaps  horizontally,  with  perfect  conformability  between  them.  The  unconform- 
abilities are  on  this  account  none  the  less  important  as  time -boundaries  in  geological 
history. 

When,  in  consecutive  epochs  of  mountain- making,  the  upturned  strata  of  the  later 
epoch  have  been  thrust  up  against  those  of  the  earlier,  by  force  acting  in  the  two  cases  from 
the  same  direction,  the  two  sets  of  strata  will  have  more  or  less  nearly  the  same  strike. 
But  their  unconformability  may  possibly  still  be  proved  (1)  by  difference  in  dip  ;  (2)  by 
difference  in  kinds  of  rocks,  when  the  rocks  are  studied  over  a  long  belt  in  the  line  of 
strike  ;  and  (3)  by  fossils,  if  the  beds  are  fossiliferous.  But  when  the  strata  are  metamor- 
phic,  and  fossils  are  therefore  absent,  the  difficulties  are  great.  Examples  occur  in  western 
Connecticut  and  eastern  New  York,  where  the  metainorphic  Taconic  rocks  come  into  con- 
tact with  Archaean.  The  first  and  second  of  the  above  criteria  may  still  be  available, 
though  with  great  uncertainty  ;  the  second  may  be  used  especially  when  the  two  sets  of 
strata  differ  in  grade  of  crystallization  or  metamorphism,  or  in  the  presence  of  some  dis- 
tinctive mineral  masses,  as  of  metamorphic  beds  of  iron  ore.  The  belt  should,  further,  be 
traced  along  the  range  of  outcrops  in  order  to  find,  if  possible,  a  region  where  there  is  a 
bend  in  the  strike  ;  for  at  such  a  bend  the  two  sets  of  strata  probably  would  not  be  found 
to  bend  alike  ;  and  to  make  the  investigation  complete,  all  possible  strikes  and  dips  should 
be  measured  and  plotted  on  a  large  map  of  the  region.  Special  care  is  needed  in  order  that 
unconformity  produced  by  a  fault  is  not  mistaken  for  true  unconformability  or  that  in 
the  bedding. 

3.    GENERAL   RESULTS   OF  OROGRAPHIC  WORK. 

1.  Effect  of  orographic  work  on  the  earth's  circumference.  —  Faults  and 
plications  are  a  measure  of  the  shortening  of  the  earth's  circumference  that  has 
taken  place  in  an  orographic  crisis.  During  the  ages  of  preparation,  the 
amount  of  shortening  in  the  making  of  the  geosyncline  has  been  small ;  for 
the  slowly  accumulating  strain  reduces  widths  only  by  the  difference  between 
the  shallow  arc  and  its  chord.  But  at  the  collapse,  as  already  shown,  the 
amount  has  been  a  score  or  more  of  miles :  74  for  the  Alps  (Heim) ;  44  for 
the  Appalachians  in  Pennsylvania;  25  for  the  Laramide  Range  in  British 
America  (McConnell). 

The  line  of  the  Appalachian  Range  is  transverse  to  a  zone  of  the  globe 
having  a  N.W.-S.E.  direction ;  and  the  Taconic  Range  and  the  Acadian  of 
Nova  Scotia  and  New  Brunswick  widen  this  zone  northward.  The  short- 
ening of  the  earth's  circumference  for  all  these  ranges  was  not  east-and-west, 
but  in  the  direction  of  this  zone.  In  this  zone  the  Archaean  nucleus  is  to  the 
northwest;  but  to  the  southeast  lies  the  Atlantic,  in  its  long  range  between 
North  and  South  America.  In  western  America,  where  the  mountains  made 
range  northwestward  instead  of  northeastward,  the  shortening  was  in  the 
direction  of  a  zone  N.E.-S.W.  in  course.  It  was  the  same  zone  of  the  globe 
that  includes  the  Alps.  The  whole  amount  of  shortening  on  the  Atlantic 
border  was  probably  not  over  50  miles  along  the  course  of  the  zone;  and 
on  the  Pacific  border  for  the  Laramide  and  other  systems  later  than  the 
Archaean,  not  over  75  miles. 


392  DYNAMICAL   GEOLOGY. 

2.  TJie  mountain  chains  and  volcanoes  of  the  continents  mostly  confined  to 
their  borders.  —  The  facts  on  these  points  are  briefly  mentioned  on  page  32 
and  beyond.     The  situation  of  the  chains  on  the  continental  borders,   so 
well  exhibited  in  North  America,  and  the  position  of  the  greater  mountain- 
mass  of   this  continent,  greater  by  25  times,  on  the  borders  of  the  larger 
ocean,  have  manifestly  a  cause  that  is  in  some  way  connected  with  the  mutual 
relations  of  the  border  region  and  the  oceanic  basin  adjoining.     The  author 
has  explained  these  features  (1847,  1873)  on  the  view  (1)  that  the  lateral 
pressure  at  work  was  lateral  thrust  chiefly  from  the  oceanic  direction  against 
the  continental  borders  (the  landward  side  of  the  border  region  being  the 
side  of  least  pressure  or  greatest  resistance);  and  (2)  that  since  the  oceanic 
area  was  depressed  below  the  level  of  the  continental,  the  thrust  was  in  a 
small  degree  obliquely  upward.     If  the  crust  in  which  the  strain  exists  has 
only  five  miles  of  depth,  there  is  still  stronger  reason  in  favor  of  this  expla- 
nation, and  for  accepting  it  also  as  accounting  for  the  making  of  the  greater 
mountain-mass  on  the  side  of  the  widest  ocean;  for  width  of  ocean,  not 
depth,  is  the  important  element.     The  view  explains  equally  the  abundance 
of  border  volcanoes. 

3.  Great  mountain   uplifts  in  the  later  part  of  geological  time  and  also 
great  igneous  ejections.  —  The  fact  that  the  highest  and  broadest  of  moun- 
tains and  the  chief  part  of  the  mass  of  the  continents  were  lifted  above  the 
ocean  mostly  after  the  Cretaceous  period  is  one  of  the  most  marvelous  in 
geological  history. 

After  the  crust  had  become  stiffened  by  the  thickening,  plication,  and 
solidification,  and  partly  the  crystallization,  of  the  strata  of  the  supercrust, 
the  chief  movement  in  mountain  regions,  caused  by  the  ever-continuing 
lateral  pressure,  was  an  upward  one,  and  then  mountain  chains  received 
through  epeirogenic  movements  their  great  heights.  Under  the  same  cir- 
cumstances, moreover,  igneous  ejections  and  volcanoes  reached  their  maxi- 
mum at  the  close  of  the  Cretaceous  and  during  the  Tertiary. 

In  correspondence  with  the  great  continental  geanticlines  of  the  Tertiary 
and  later  time,  there  should  have  been  oceanic  geosynclines,  for  the  material 
constituting  the  rising  mass  could  have  had  no  other  source  than  the  crustal 
mass  beneath  the  oceans.  On  this  point  there  is  the  great  fact  of  the  sub- 
sidence over  the  central  Pacific,  described  on  page  349,  of  which  the  coral 
islands  are  a  monumental  record.  Its  area  was  hardly  less  than  6000  miles 
in  length,  and  the  breadth,  reckoning  only  from  the  Hawaiian  to  the  Friendly 
Islands,  over  2500  miles.  Such  a  subsidence  fully  meets  the  demands  of 
the  Pacific-border  geanticline  of  North  America.  It  suggests,  also,  that  the 
other  great  mountain-masses,  uplifted  during  the  Tertiary  and  Quaternary, 
among  them  the  lofty  Andes  and  the  still  loftier  Himalayas,  derived  a 
supply  of  material  by  a  like  method  from  beneath  the  oceans.  Under  this 
compensating  relation,  the  two  great  movements  become  one  epeirogenic 
evenly,  and,  therefore,  the  combined  result  of  one  comprehensive  cause. 

4.  North    America    a    type-continent.  —  Among    the    continents,    North 


HYPOGEIC   WORK.  393 

America  best  exhibits  typical  continental  growth,  because  it  stands  by 
itself  between  the  two  oceans,  free  from  other  lands  on  the  east,  south, 
and  west.  In  this  it  is  greatly  in  contrast  with  Europe  and  Asia.  In  all 
its  structure  it  shows  that  its  orographic  courses  were  outlined  at  its  incep- 
tion, and  that  its  features  were  gradually  developed  from  age  to  age,  in 
accordance  with  the  foreshadowed  system.  The  Archaean  protaxes  have 
almost  the  lengths  of  the  adjacent  continental  borders,  and  the  systems  of 
ranges  of  later  elevation,  on  the  Atlantic  and  Pacific  sides,  have  parallel 
courses  and  like  extent.  They  are  not  irregularly  distributed  groups  or 
knots  of  mountains,  but  elevated  lines  in  the  continental  structure,  orderly 
placed  according  to  principles  and  forces  that  were  already  at  work  in 
Archaean  time. 

Hock-making  went  forward  under  like  comprehensive  methods  with  the 
mountain-making.  When  Archaean  time  closed,  North  America  comprised  a 
great  Interior  Continental  or  Mediterranean  Sea,  partially  separated  by  the 
protaxes  from  the  continental-border  seas  on  the  Atlantic  and  Pacific ;  and, 
besides,  there  were,  in  some  parts  of  the  borders,  parallel  troughs  or  basins 
between  Archaean  confines.  Through  the  following  ages,  these  seas  were 
doing  their  various  work  in  rock-making,  bringing  first  to  a  finish,  and 
emergence  with  orographic  aid,  the  eastern  half  of  the  continent ;  and  then 
giving  a  like  degree  of  progress  and  emergence  to  the  western  half ;  and, 
finally,  under  a  comprehensive  agency,  carrying  the  whole  area,  from  east  to 
west,  to  completion. 

5.  The  earth  an  individual  in  development.  —  The  system  of  feature-lines, 
displayed  in  the  islands  of  the  Pacific,  is  virtually  that  of  a  hemisphere,  for 
nearly  half  of  the  equator  lies  between  the  ocean's  eastern  and  western 
limits.  It  may  be  rightly  taken,  therefore,  as  the  system  of  the  globe.  All 
north-and-south  lines  are  subordinate  lines  in  this  system.  There  is  no 
network  of  pentagonal  lines  of  dislocation  (De  Beaumont),  or  of  tetrahedral 
lines  (William  L.  Green,  1857-1887),  or  of  dodecahedral  lines,  as  urged  by 
E.  Owen,  of  Indiana,  in  his  later  paper  on  the  earth's  features  (1888);  for 
the  existence  of  continental  regions  and  oceanic  basins  implies  local  differences 
in  the  nature  of  the  material  over  the  sphere,  when  surface  cooling  began, 
that  made  such  lines  of  symmetry  impossible.  Instead,  the  actual  physiog- 
nomy includes  long  parallel  ranges  of  lines,  often  bending  in  great  curves, 
with  transverse  lines  nearly  at  right  angles,  and  a  reference  in  all  to  the 
positions  and  forms  of  the  continental  and  oceanic  areas.  The  island  chains 
of  the  Pacific,  1000  to  5000  miles  long,  are  separated  by  underwater  valleys, 
reaching  in  some  cases  to  depths  of  28,000  feet,  or  over  40,000  below  the 
highest  island  summits.  The  system  of  feature-lines  of  the  oceans  is 
exhibited  also  by  the  continents,  but  with  irregularities  incident  to  the 
forms,  positions,  and  consequent  resistances  of  the  nucleal  land-masses. 

System  through  regular  progress  is  abundantly  proved,  but  the  special 
causes  determining  the  details  of  the  system  are  not  yet  all  understood. 
The  following  are  some  of  the  points  awaiting  explanation  :  — 


394  DYNAMICAL   GEOLOGY. 

(1)  The  gathering  of  the  dry  land,  the  continents,  the  earth's  individ- 
ualities, and  arenas  of  progress,  mostly  toward  the  north  pole,  and  of  the 
waters  as  largely  toward  the  south  pole,  the  great  cause  of  continental  differ- 
ences in  the  system  of  progress. 

(2)  The  attitude  of  the  continents  on  the  globe,  each  mass  having  the 
broader  extremity  to  the  north  and  narrowing  southward  —  a  fact  which 
Bacon,  in  his  Novum  Organum,  set  forth  as  a  problem  for  solution. 

(3)  The  zigzag  arrangement  of  the  northern  and  southern  continents, 
South  America  having  its  center  40°  east  of  that  of  North  America,  and 
Australia,  as  far  east  of  that  of  Asia. 

(4)  The  separation  of  the  northern  and  southern  continents  by  a  volcanic 
belt  that  girts  the  sphere. 

(5)  The  two  systems  of  courses  in  the  grand  feature-lines  of  the  conti- 
nents and  oceans  nearly  at  right  angles  with  one  another,  the  more  equatorial 
and  most  prevalent  varying  between  N.  60°  W.  and  N.  70°  W.,  but  curving 
to  N.  30°  W.,  and  the  transverse  system  with  correlate  variations. 

(6)  The  existence  of  a  greater  mean  depth  in  the  western  half  of  the 
Atlantic   and   Pacific    Oceans   than  in   the   eastern  half,   notwithstanding 
the  fact  that  the  continental  border  adjoining  the  west  Pacific  is  a  region  of 
high  mountains  with  many  volcanoes  in  the  continental  islands,  and  that 
the  border  adjoining  the  west  Atlantic  has  the  lower  mountains  of  North 
America  and  no  volcanoes. 

These  characteristics  of  the  earth  necessarily  date  from  the  beginning  of 
solidification ;  and  the  first  —  the  existence  of  a  larger  part  of  the  continental 
masses  in  the  northern  hemisphere  and  of  the  oceanic  area  in  the  southern — 
may  have  involved  the  others.  For,  if  the  alleged  excess  of  density  in  the  crust 
beneath  the  oceans  is  owing  to  the  prevalence  of  basaltic  rocks,  the  crust  of 
the  oceanic  basin  would  have  remained  in  fusion  after  that  of  the  continental 
had  generally  cooled  through  an  era  long  enough  for  a  loss  of  300°  to  500° 
Fahrenheit,  —  a  fact  that  would  have  determined  differential  conditions  and 
consequences  at  the  first  cooling  of  the  earth's  crust. 

The  zigzag  arrangement  of  the  continents  has  been  attributed  to  torsion ; 
and  the  belt  of  volcanoes  that  girts  the  world  has  been  pointed  out  as  the 
belt  of  maximum  torsion,  and  the  courses  of  the  earth's  feature-lines  as 
consequences  in  part  of  the  pressure  or  tension  attending  torsion ;  and  thus 
an  explanation  that  reaches  deeply  into  the  subject  of  origins  has  already 
been  presented. 

W.  L.  Green  (1875  and  1877),  in  The  Vestiges  of  a  Molten  Globe,  sug- 
gested the  idea  that  the  mass  of  the  continental  plateaus,  occupying  the 
northern  hemisphere,  caused,  during  the  incipient  stage  of  the  first  formed 
crust,  a  retardation  in  the  rotation  of  this  part  of  the  floating  crust,  and 
thereby  "a  shearing  strain  .  .  .  between  the  crusts  of  the  northern  and 
southern  hemispheres,"  and  hence  a  yielding  to  this  strain  along  the  earth's 
great  volcanic  belt ;  remarking  that  thus  "  South  America  became  separated 
from  its  northern  half  continent,  and  pushed  toward  Africa,"  while  Asia,  in 


HYPOGEIC    WORK. 


395 


the  northern  hemisphere,  was  crowded  westward  on  to  Europe  and  Africa, 
leaving  Australia  to  the  eastward. 

Daubree,  in  1880,  explained  the  same  characteristics  of  the  sphere  by 
reference  to  torsion  in  the  crust  during  its  contraction,  and  referred  to 
the  facts  as  according  with  his  experiments  described  in  his  Experimental 
Geology. 

W.  Prinz  published  a  paper  in  the  Annuaire  de  V Observatoire  Royal  de 
Bruxelles  for  1891,  in  which  he  points  out  the  resemblances  between  the 
great  continental  torsion  courses  of  the  earth,  and  the  lines  that  have  been 
observed  on  some  of  the  planets.  The  western  outline  of  North  and  South 
America  shows  well  the  obliquity  of  one  of  the  greater  torsion  courses  and 
movements.  On  the  following  diagram,  Fig.  347,  it  is  the  outline  to  the 
left.  Parallel  with  this,  as  Prinz  explains,  and  about  90°  to  the  eastward, 

347. 


Oblique  courses  in  the  earth's  grander  outlines.     Prinz. 


there  is  another,  that  of  the  western  coast  of  Africa,  continued  northwest- 
ward to  Greenland  ;  and  90°  farther  eastward,  there  is  a  third,  following  the 
course  of  the  western  side  of  Asia,  from  the  Urals  and  Spitzbergen  to  western 
Sumatra  and  Australia.  A  fourth  is  also  supposed  by  him  to  be  indicated  in 
the  middle  of  the  Pacific,  nearly  90°  more  to  the  eastward,  where  the  great 
central  chain  of  islands  in  the  ocean  bends  northward,  and  crosses  the  equa- 
tor in  the  Marshall  Islands.  Prinz  shows  further  from  published  maps  that 
similar  oblique  lines  have  been  observed  on  Mars  (Fig.  348),  and  less  dis- 
tinctly on  Venus  and  Jupiter.  Finally,  he  states  that  M.  Duner,  by  means 
of  the  spectroscope,  has  been  able  to  determine  that  in  the  sun  the  75th 


396 


DYNAMICAL    GEOLOGY. 


degree  of  latitude   makes  a  complete  revolution  in  38-6  days,  while  the 
equator  revolves  in  25'5  days. 

The  fact  of  torsion  appears  thus  to  be  sustained  for  the  other  planets 
as  well  as  for  the  earth. 


348. 


Oblique  feature-lines  on  Mars.    Prinz. 

Prinz  introduces,  in  closing,  the  diagram  in  Fig.  349  to  illustrate  the 
general  scheme  of  torsional  movements.  He  implies  that  such  movement  may 

have  begun  in  the  incipient 
stages  of  surface  consolida- 
tion, whenever  the  continen- 
tal and  oceanic  areas  began 
to  be  differentiated,  and  that 
in  the  process  a  cleavage 
structure  was  produced  that 
determined  the  system  of 
fractures  in  the  earth's  sur- 
face, and  thereby  the  system 
in  the  earth's  feature -lines. 
But  he  adds  that  the  solu- 
tion of  all  the  questions  that 
arise  demands  the  profound- 
est  knowledge  of  celestial 
mechanics,  as  well  as  much 
experiment,  and  a  complete  discussion  of  the  records  in  the  earth's  structure. 

Historical  geology  adds  greatly  to  the  interest  of  geomorphic  work,  by 
presenting  in  detail  the  connection  of  mountain-making  movements  with  the 
preparatory  stratigraphic  events,  and  also  by  bringing  out  to  view  the  bear- 
ings of  these  great  topographical  changes  on  the  physical  conditions  of  the 
earth,  and  their  influence  on  biological  distribution  and  progress. 


PAKT  IV. 


HISTORICAL   GEOLOGY. 

SUBDIVISIONS   IN  GEOLOGICAL   HISTORY  AND  METHODS   OF 

CORRELATION. 

NATURE  OF  SUBDIVISIONS  IN  THE  HISTORY. 

IN  the  study  of  geology,  there  is  often  an  expectation  to  find  strongly 
drawn  lines  between  the  eras  and  periods,  or  the  corresponding  subdivisions 
of  the  rocks  ;  but  geological  history  is  like  human  history  in  this  respect. 
Time  is  one  in  its  course,  and  all  progress  one  in  plan. 

Some  grand  strokes  there  may  be,  — as  in  human  history  there  is  a  begin- 
ning in  man's  creation,  and  a  new  starting-point  in  the  advent  of  Christ. 
But  all  attempts  to  divide  the  course  of  progress  in  man's  historical  devel- 
opment into  periods  with  bold  confines  are  fruitless.  We  may  trace  out  the 
culminant  phases  of  different  periods  in  that  progress,  and  call  each  culmi- 
nation the  center  of  a  separate  period.  But  the  germ  of  the  period  was  long 
working  onward  in  preceding  time,  before  it  finally  came  to  its  full  develop- 
ment and  stood  forth  as  the  characteristic  of  a  new  era  of  progress.  It  is  all 
one  progress,  while  successive  phases  stand  forth  in  that  progress. 

In  geological  history,  the  earliest  events  were  simply  physical.  While 
the  inorganic  history  was  still  going  on  (although  finished  in  its  more  funda- 
mental ideas) ,  there  was,  finally,  the  introduction  of  life,  —  a  new  and  great 
step  of  progress.  That  life,  beginning  with  the  lower  grades  of  species, 
was  expanded  and  elevated,  through  the  appearance  of  new  types,  until  the 
introduction  of  Man.  In  this  organic  history,  there  are  successive  steps  of 
progress,  or  a  series  of  culminations.  As  the  tribes,  in  geological  order,  pass 
before  the  mind,  the  reality  of  one  age  after  another  becomes  strongly  appar- 
ent. The  era  of  Mammals,  the  era  of  Reptiles,  and  the  era  of  Coal-plants 
oome  out  to  view,  like  mountains  in  the  prospect,  although,  if  the  mind 
should  attempt  to  define  precisely  where  the  slopes  of  the  mountain  end,  as 
they  pass  into  the  plain  around,  it  might  be  greatly  embarrassed. 

We  note  here  the  following  important  principles:  — 

First.  The  reality  of  an  era  in  history  is  marked  by  the  development  of 
some  new  idea  in  the  system  of  progress. 

397 


398  HISTORICAL   GEOLOGY. 

Second.  The  beginning  of  the  characteristics  of  an  era  is  to  be  looked 
for  in  the  midst  of  a  preceding  era ;  and  the  marks  of  the  future  coming  out 
to  view  are  prophetic  of  that  future. 

Third.  The  end  of  an  era  may  come,  either  after  the  full  culmination 
of  the  idea  or  phase,  or  earlier,  at  the  commencing  prominence  of  a  new  and 
grander  phase  in  the  history.  It  may  be  as  ill-defined  as  the  beginning, 
although  its  prominent  idea  may  stand  out  boldly  to  view.  Thus  the  era  of 
Coal-plants  was  preceded  by  the  occurrence  of  related  plants  far  back  in  the 
Devonian.  The  era  of  Mammals  was  foreshadowed  by  the  appearance  of 
mammals  long  before,  in  the  course  of  the  Reptilian  era.  And  the  era  of 
Reptiles  was  prophesied  in  types  that  lived  in  the  earlier  Carboniferous  era. 
Such  is  system  in  all  history.  Nature  has  no  sympathy  with  the  art  which 
runs  up  walls  to  divide  off  her  open  fields. 

Fourth.  Mere  length  of  time,  without  culminating  or  characterizing  events 
beyond  that  of  rock-making,  is  not  a  criterion  of  value  in  the  subdividing 
of  geological  history. 

CORRELATION  OF  THE  RECORDS. 

The  chronological  order  is  that  demanded,  as  in  any  history.  The  first 
object  is,  accordingly,  to  ascertain  which  are  equivalent  strata,  or  those  of  the 
same  geological  horizon,  and  where  in  the  chronological  succession  each 
stratum  belongs. 

As  even  the  shorter  divisions  of  geological  time  have  in  general  been  of 
very  long  duration,  the  equivalent  or  correlate  strata  of  distant  regions  can- 
not be  known  to  be  precisely  synchronous  in  origin.  A  long  time,  measured 
by  thousands  of  years,  may  in  fact  have  intervened  between  the  commence- 
ment of  beds  that  are  most  alike  in  all  those  points  by  which  age  and  equiv- 
alency are  determined. 

Huxley,  in  view  of  the  impossibility  of  determining  true  synchronism, 
proposed  to  designate  by  the  term  homotaxial  (from  the  Greek  6//,os,  same, 
and  ra£is,  order)  those  strata,  in  regions  more  or  less  widely  separated,  that 
have  apparently  the  same  relative  position  in  the  geological  series. 

Difficulties.  —  The  following  are  some  of  the  difficulties  encountered  in 
attempts  to  ascertain  the  true  chronological  succession  :  — 

1.  The  stratified  rocks  of  the  globe  include  an  indefinite  number  of  lime- 
stones, sandstones,  shales,  and  conglomerates ;  and  they  occur  horizontal 
and  displaced  ;  conformable  and  unconformable ;  part  in  America  and  part 
in  Europe,  Asia,  and  Australia ;  here  and  there  coming  to  view,  but  over 
wide  areas  buried  beneath  soil  and  forests. 

Moreover,  even  the  same  bed  often  changes  its  character  from  a  sandstone 
to  a  shale,  or  from  a  shale  to  a  limestone  or  a  conglomerate,  or  again  to  a 
sandstone,  within  a  few  miles  or  scores  of  miles,  and  sometimes  within  a  few 
rods;  or,  if  it  retains  a  uniform  composition,  it  changes  its  color  so  as  not  to 
be  recognized  by  the  mere  appearance.  In  the  United  States,  many  a  sand- 


SUBDIVISIONS   IN   GEOLOGICAL   HISTORY.  399 

stone  in  New  York  and  Pennsylvania  is  of  cotemporaneous  origin  with  a 
limestone  in  the  Ohio  and  Mississippi  valleys.  Some  rocks  in  eastern  New 
York  are  not  found  in  the  western  part  of  that  state,  and  some  in  the  central 
and  western  part  not  in  the  eastern. 

2.  In  all  periods,  sand-beds,  mud-beds,  clay-beds,  pebble-beds,  and  lime- 
stone-beds have  been  simultaneously  in  progress  over  different  parts  of  the 
globe ;  and,  if  a  period  is  known  in  geology  as  solely  a  period  of  limestone, 
it  is  because  science  has  not  yet  discovered  where  the  beds  of  sand,  mud, 
or  pebbles  were  being  deposited  while  the  limestone  was  making  over  its 
regions.     The  idea  of  a  period  of  sandstone-making,  or  of  limestone-making, 
is  therefore  an  absurdity ;  for  sand  deposits  are  local ;  a  short  distance  off, 
there  may  have  been,  in  all  times,  as  now,  mud  deposits.     Still,  it  is  true 
that,  over  continental  seas,  the  prevailing  depositions  have  sometimes  been 
of  limestone  material,  and  sometimes  of  mud  or  sand ;  yet  this  has  been  true 
for  certain  great  regions  in  the  seas  of  a  continent,  rather  than  for  all  its 
seas  at  once. 

3.  Again,  a  stratum  of  one  era  may  rest  upon  any  stratum  in  the  whole 
of  the  series  below  it,  —  the  Coal-measures  on  either  the  Archaean,  Silurian, 
or  Devonian  strata ;  and  the  Jurassic,  Cretaceous,  or  Tertiary  on  any  one  of 
the   earlier   rocks,  the   intermediate   being   wanting.      The   Quaternary   in 
America  in  some  places  rests  on  Archaean  rocks,  in  others  on  Silurian  or 
Devonian,  in  others  on  Cretaceous  or  Tertiary. 

4.  In  addition,  denudation  and  uplifts  have  thrown  confusion  among  the 
beds,  by  disjoining,  disarranging,  and  making  complex  what  once  was  simple. 

Amidst  all  these  sources  of  difficulty,  how  is  the  true  order  ascertained  ? 

Means  of  correlation.  — The  following  are  the  means  employed :  — 

1.  Order  of  superposition.  —  When  strata  are  little  disturbed,  vertical 
sections  give  the  true  order  in  those  sections ;  and  so  also  may  outcrops  of 
inclined  strata  over  the  surface  of  a  country.  In  using  this  method  by 
superposition,  several  precautions  are  necessary. 

Precaution  1.  —  Proof  should  be  obtained  that  the  strata  have  not  been 
folded  upon  one  another,  so  as  to  make  an  upper  layer  a  lower  one  (see  page 
104),  —  a  condition  to  be  suspected  in  regions  where  the  rocks  are  much 
tilted. 

Precaution  2.  —  It  should  be  seen  that  the  strata  350. 

under  examination  are  continuous.  A  fault  in  the 
rocks  may  deceive ;  for  it  makes  layers  seemingly 
continuous  which  are  not  so.  Faults  are  common  in 
regions  of  upturned  rocks  and  may  occur  when  the 
dip  is  slight.  In  some  cases,  beds  forming  the  upper 
part  of  a  bluff  (as  ab,  Fig.  350)  have  settled  down 

bodily  (c)  to  the  bottom,  so  as  to  seem  to  be  continuous  with  the  older  ones 
of  the  bottom  (as  c  with  d).  In  other  cases,  caverns  in  rocks  have  been 
filled  through  openings  from  above,  and  the  same  kind  of  mistake  made. 


400  HISTORICAL   GEOLOGY. 

When  the  continuity  can  be  established,  the  evidence  may  sometimes  lead 
to  unexpected  results.  For  example,  it  may  be  found  that  a  coal-bed, 
followed  for  some  miles  to  one  side  or  the  other,  is  continuous  with  a  shale, 
and  both  are  actually  one  layer ;  that  a  sandstone  is  one  with  a  limestone  a 
few  miles  off ;  that  an  earthy  limestone  full  of  fossils  is  identical  with  a 
layer  of  white  crystalline  marble  in  a  neighboring  district ;  or  that  a  fossi- 
liferous  shale  of  one  region  is  the  same  stratum  with  the  mica  schist  of 
another. 

Precaution  3.  — Note  whether  the  strata  overlie  one  another  conformably 
or  not,  —  that  is,  conformably  as  regards  bedding. 

Precaution  4.  —  Remember  that,  where  one  bed  overlies  another  conform- 
ably, it  does  not  follow  necessarily  that  these  beds  belong  to  consecutive 
periods,  as  has  been  above  explained. 

The  criterion  mentioned,  —  order  of  superposition,  —  unless  connected 
with  others,  gives  no  aid  in  comparing  the  rocks  of  distant  or  disconnected 
regions.  For  this  purpose,  other  means  must  be  employed. 

2.  Color,  texture,  and  mineral  composition.  —  These  characteristics  may 
sometimes  be  used  to  advantage,  but  only  within  limited  districts  and  always 
with  distrust.     There  were  at  one  time  in  geology  an  "old  red  sandstone" 
and  a  "  new  red  sandstone  " ;  and,  whenever  a  red  sandstone  was  found,  it 
was  referred  at  once  to  one  or  the  other.     But  it  is  now  well  understood 
that  color  is  of  little  consequence,  even  within  a  small  geographical  range. 

Mineral  composition  has  more  value  than  color,  especially  when  it  is  not 
one  of  the  common  kinds.  But  it  is  usually  to  be  disregarded. 

One  inference  from  the  mineral  constitution  of  a  stratum  is  safe ;  that  is, 
that  a  stratum  is  more  recent  than  the  rock  from  which  its  material  was  derived. 
Hence,  an  imbedded  fragment  of  some  known  rock  may  afford  important 
evidence  with  regard  to  the  age  of  the  containing  stratum.  But  the  presence 
of  such  a  fragment  does  not  prove  that  a  long  time  intervened ;  the  imbed- 
ding may  have  happened  in  the  same  period  in  which  the  earlier  beds  of  the 
formation  were  made.  The  beds  made  and  consolidated  in  modern  time  are 
often  torn  up  by  the  waters  and  put  into  new  beds  in  some  other  place. 
Coral  limestones  of  recent  seas  are  often  conglomerates  of  the  recent  coral 
limestone.  Limestone  breccia  is  sometimes  formed  out  of  the  blocks  at  the 
foot  of  a  bluff  of  limestone  from  which  the  blocks  had  fallen. 

3.  Although  mineral  composition  is  ordinarily  unsafe,  it  has  value  when 
two  or  more  conformable  strata  of  constant  mineral  characters  accompany 
one  another.      Such  evidences  may  prove  identity  for  hundreds  of  miles. 
The  association  of  schist,  limestone,  and  quartzyte  from  central  Vermont  to 
Connecticut  and  beyond,  with  only  small  gradational  changes  in  each  of  the 
rocks,  serves  to  identify  the  Taconic  series  through  its  wide  distribution. 

4.  Fossils.  —  The  criterion  for  determining  the  chronological   order   of 
strata  dependent  on  kinds  of  fossils  takes  direct  hold  upon  time,  and,  there- 
fore, is  the  best ;  and,  moreover,  it  serves  for  the  correlation  of  rocks  all  over 
the  world.     The  life  of  the  globe  has  changed  with  the  progress  of  time.     Each 


SUBDIVISIONS   IN    GEOLOGICAL   HISTORY.  401 

epoch  has  had  its  peculiar  species,  or  peculiar  groups  of  species.  Moreover, 
the  succession  of  life  has  followed  a  grand  law  of  progress,  involving  under 
a  single  system  a  closer  and  closer  approximation  in  the  species,  as  time 
moved  on,  to  those  which  now  exist.  It  follows,  therefore,  that  identity  of 
species  of  fossils  proves  approximate  identity  of  age. 

Equivalency  is  sometimes  shown  in  an  identity  of  species ;  more  often  in 
a  parallel  series  of  nearly  related  species ;  often  by  an  identity  or  close  rela- 
tion in  the  genera  or  families ;  often  also  in  some  prominent  peculiarity  of 
the  various  species  under  a  family  or  class. 

Through  a  comparison  of  fossils,  it  was  discovered  that  the  Chalk  forma- 
tion exists  on  the  Atlantic  border  of  the  United  States,  although  the  region 
contains  no  chalk;  that  the  Coal  formation  of  North  America  and  that  of 
Newcastle,  England,  belong  in  all  probability  to  the  same  geological  age ; 
and  so  on. 

The  progress  in  life  has  not  consisted  in  change  of  species  alone.  The 
species  of  a  genus  often  present,  in  successive  periods,  some  new  feature ;  or 
the  higher  groups  under  an  order  or  class  some  modification,  or  some  new 
range  of  genera,  so  that,  even  when  the  species  differ,  the  habit  or  general 
characters  of  the  species,  or  the  range  of  genera  or  families  represented,  may 
serve  to  determine  the  era  to  which  a  rock  belongs,  or  at  least  to  check  off 
the  eras  to  which  it  does  not  belong.  Thus  Spirifer,  a  genus  of  mollusks, 
which  has  a  narrow  form  in  the  Silurian,  has  often  a  very  broad  form  in  the 
course  of  the  Devonian  and  the  Carboniferous  ages.  Ganoid  fishes,  which 
have  vertebrated  tails  through  long  ages,  have  their  tails  not  vertebrated  in 
after  time.  Trilobites  become  wholly  extinct  at  a  certain  epoch  in  their  his- 
tory. These  are  examples  of  a  principle  availed  of  in  multitudes  of  cases 
presenting  minor  differences. 

Much  aid  is  derived  also  from  the  canon  brought  forward  by  Agassiz  in 
the  first  volume  of  his  Poissons  Fossiles  (1833,  pages  208-270),  and  con- 
sidered at  length  in  one  of  the  chapters  in  his  Natural  History  of  the  United 
States  (i.  112,  1857)  :  that,  under  the  various  tribes,  the  geological  succession 
of  species  often  corresponds  in  some  of  the  more  general  characteristics 
with  the  succession  of  phases  in  the  development  of  living  representatives  of 
those  tribes.  In  other  words,  geological  succession  and  modern  embryologi- 
cal  succession  have  near  parallelisms. 

Agassiz  says,  in  his  work  on  Fossil  Fishes  (vol.  i,  page  169)  :  "  J'ai  deja  eu  plus  d'une 
fois  occasion  de  faire  remarquer  la  grande  analogic  qu  'il  y  a  entre  certain es  formes 
embryoniques,  qui  sont  passageres  dans  le  developpement  des  individus,  et  les  caracteres 
constans  d'une  foule  de  genres  de  differentes  families,  qui  n'ont  que  peu  de  representans 
dans  la  creation  actuelle,  ou  qui  sont  completement  eteints."  In  his  work  on  the  Natural 
History  of  the  United  States,  on  page  112  of  the  chapter  on  "the  Parallelism  between  the 
geological  succession  of  animals  and  the  embryonic  growth  of  their  living  representa- 
tives," Agassiz  states  the  principle  as  follows  :  "The  phases  of  development  of  all  living 
animals  correspond  to  the  order  of  succession  of  their  extinct  representatives  in  past 
geological  time." 

DANA'S  MANUAL  —  26 


402  HISTORICAL  GEOLOGY. 

In  illustration :  the  vertebrated  tails  of  the  ancient  Ganoids  is  one  ex- 
ample, since  this  feature  is  a  characteristic  of  the  young  of  living  Ganoids, 
and  also  of  some  other  living  fishes.  The  cartilaginous  skeleton  of  the 
ancient  Ganoids  is  another  embryonic  feature.  The  stem  of  the  ancient 
Crinoids  occurs  in  the  young  of  the  related  Comatula.  The  Mastodon,  as 
regards  its  teeth,  says  Agassiz,  and  in  some  other  points,  is  embryonic  in  its 
relations  to  the  Elephant. 

Paleontologists  of  skill  derive  a  degree  of  prophetic  power  through  the 
aid  of  the  canon.  The  shells  of  Ammonites  have  been  shown  by  A.  Hyatt  to 
afford  an  excellent  illustration  of  the  principle.  Noting  that  the  coiled  shell 
contained  within  it  all  the  forms  it  had  passed  through  from  the  embryo  stage 
to  the  adult,  he  proved  by  his  studies  of  the  shells  of  different  genera  that  the 
embryological  succession  corresponded  in  a  general  way  with  the  geological 
succession,  and  hence  that  the  position  in  the  geological  scale  of  any  new 
species  was  approximately  determinable  from  its  form.  It  is  obvious  that 
through  the  knowledge  thus  obtained  stratigraphical  doubts  may  often  be 
removed.  Moreover,  where  direct  paleontological  observation  has  ascertained 
in  particular  cases  the  steps  of  progress  in  the  development  of  organs,  as,  for 
example,  those  of  the  teeth  in  Mammals,  the  facts  become  a  basis  for  further 
use  in  the  same  direction.  But  decisions  on  such  grounds  have  to  be  made 
with  great  reserve ;  since  there  were  often,  throughout  paleontological  his- 
tory, retrograde  steps  in  the  various  tribes  of  species,  and,  not  unfrequently, 
in  some  organs  when  the  general  progress  was  upward.  Man  stands  at 
the  head  of  Mammals,  and  yet,  as  regards  his  teeth,  he  is  below  the  Monkeys, 
and  related  to  the  earliest  Tertiary  Mammals. 

By  the  methods  which  have  been  above  described,  great  progress  has 
been  made  in  arranging  the  rocks  of  the  different  continents  in  a  chronologi- 
cal series.  North  America  has  large  blanks  in  the  series  which  in  Europe 
are  filled.  In  this  and  other  ways  the  countries  of  the  world  are  contribu- 
ting to  a  general  system  of  life  history. 

Precautions  in  the  use  of  fossils  for  correlation.  —  Precaution  is  required 
for  the  following  reasons  :  — 

1.  The  difference  in  species  attending  difference  of  conditions  in  climatCj 
soilj  etc.  In  the  same  regions,  during  any  era,  the  species  of  the  land  differ 
from  those  of  the  waters  ;  those  of  fresh  water  from  those  of  salt ;  those  of 
the  surface  or  shallow  waters  from  those  of  deeper ;  those  of  warm  waters 
from  those  of  cold,  whether  at  the  surface  or  in  the  deep  ocean  where 
oceanic  currents  make  differences  of  temperature ;  those  of  warm  or  dry 
lands  from  those  of  cold  or  wet ;  those  of  clear  open  seas  from  those  of 
muddy  waters  or  near  muddy  seashores ;  those  of  rocky  bottoms  from  those 
of  muddy ;  etc.  Hence,  an  ancient  rock  made  in  a  clear  sea,  as  a  limestone, 
will  necessarily  contain  very  different  fossils  from  a  rock  that  was  made  of 
mud,  although  they  were  formed  at  the  very  same  time,  in  the  same  waters, 
and  within  a  hundred  miles  of  one  another.  Even  a  hundred  yards  may  be 
all  that  separates  widely  different  groups  of  species.  Again,  a  rock  made 


SUBDIVISIONS  IN   GEOLOGICAL  HISTORY.  403 

in  fresh  waters  will  differ  in  its  fossils  still  more  widely  from  that  made 
synchronously  in  salt  waters ;  a  rock  made  in  shallow  waters  from  one  made 
at  great  depths ;  a  rock  made  in  the  tropics  from  one  made  in  the  temperate 
zone  or  the  arctic,  provided  the  zones  at  the  time  of  the  making  differed  as 
they  do  now  in  climate.  Hence,  a  very  considerable  difference  in  the  fossils 
of  rocks  is  consistent  with  their  being  contemporaneous  in  origin. 

?.  As  a  consequence  of  the  above  facts,  or  the  dependence  of  life  on 
food,  temperature,  and  other  physical  conditions,  migrations  in  species 
or  faunas  will  take  place  whenever  there  is  a  marked  change  in  the  waters; 
it  may  be  for  a  few  miles  or  many.  Barrande,  first  in  1852,  pointed  to 
examples  of  such  migrations  in  his  "  Colonies,"  as  he  styled  them ;  cases 
of  advanced  occurrence  locally  of  a  fauna  that  afterwards  disappeared,  but 
later  became  the  prevailing  fauna  of  a  region,  which  he  explained  by  migra- 
tion, implying,  as  Geikie  observes,  that  "particular  species  appeared  with 
the  conditions  favorable  to  their  spread  and  disappeared  when  these  ceased." 
The  case  is  the  same  when  the  fauna  of  a  bed,  which  has  apparently  become 
extinct,  has  recurrences  in  an  overlying  stratum  whenever  there  is  a  recur- 
rence of  the  kind  of  deposit.  In  and  out  the  species  go  with  the  changing 
conditions.  Hence,  as  H.  S.  Williams  has  said,  "  the  actual  order  of  faunas 
met  with  in  a  vertical  section  is  not  necessarily  expressive  of  biological 
sequence,  but  only  of  the  sequence  of  the  occupants  of  that  particular  area." 
Such  recurrences  of  species  are  likely  to  be  met  with  in  all  regions  where 
fine  shales,  coarse  shales,  argillaceous  sandstones,  quartzose  sandstones,  with 
or  without  limestones  of  varying  purity,  are  in  alternation. 

3.  The  difference  in  the  time  at  which  species  or  groups  have  begun  to  exist 
in  different  regions.     The  several  continents  may  not  have  been  exactly 
parallel,  in  all  the  steps  of  progress  in  the  life  of  the  globe.     Certain  families 
may  have  commenced  a  little  earlier  in  one  than  in  another ;  or  again,  one  conti- 
nental sea  or  region,  over  a  continent,  may  have  received  some  of  its  species 
by  migration  from  another,  long  after  their  first  appearance.     Here  is  a 
source  of  doubt :  what  may  be  due,  on  one  side,  to  special  continental  idiosyn- 
crasies in  condition  or  history,  and,  on  the  other,  to  migrational  distribu- 
tion, is  always  to  be  carefully  considered.      An  example  of  the  doubts  and 
difficulties  which  may  be  thus  occasioned  is  afforded  by  the  Cretaceous  and 
Tertiary  formations  of  North  America  and  Europe.     Fossil  plants  of   the 
Rocky  Mountain  Cretaceous  have  been  pronounced  Tertiary  by  European 
paleontologists  who  judged  from  comparisons  with  European  Tertiary  species ; 
and  yet  the  animal  fossils  of  associated  beds  made  it  certain  that  they  were 
Cretaceous  :  and  the  query  has  thence  arisen  whether  the  European  plants 
may  not  be  the  successors  of   emigrants   of  Cretaceous  American  species 
which,  through  this  means,  became  characteristic  in  Europe  of  a  post-Cre- 
taceous period,  or,  whether  the  differences  are  not  indigenous  to  the  sepa- 
rate continents. 

4.  The  difference  in  the  time  at  which  species  or  groups  of  species  of  differ- 
ent regions  have  become  extinct.     In  one  region,  changes  may  have  caused 


404  HISTORICAL   GEOLOGY. 

speeies  or  genera  (or  higher  groups)  to  disappear,  while,  in  another  sub- 
jected to  the  same  conditions  or  causes  of  catastrophe,  the  same  species,  or 
at  least  the  same  genera  (or  higher  groups),  may  have  continued  on  through 
another  period.  Genera  or  Families  may  have  become  extinct  sooner  on  one 
continent,  or  part  of  a  continent,  than  on  another ;  or  in  one  ocean,  or  part 
of  an  ocean,  than  in  another.  Again,  catastrophes  may  affect  the  shallow 
borders  of  an  ocean,  and  not  reach  to  a  depth  of  a  hundred  fathoms. 

5.  The  absence  of  fossils  from  a  formation,  or  their  extreme  fewness, 
even  when  the  formation  is  thousands  of  feet  thick,  is  no  evidence  as  to  the 
paucity  of  life  in  the  era.     The  absences  may  be  owing  to  local  conditions ; 
or  to  the  trituration  of  fossils  to  the  finest  of  particles  which  infiltrating 
waters  could  wash  out ;  or  to  the  waters  of  the  region  having  been  fresh. 

A  case  in  the  later  Paleozoic  is  that  of  the  Devonian  Catskill  Red  sand- 
stone 3000  to  4000  feet  thick,  whose  fossils  are  very  few  brackish-water  or 
fresh-water  species.  When  formed,  the  seas  of  the  world  contained  as  large 
and  varied  a  fauna  as  in  the  period  of  the  great  Devonian  limestones  or  that 
of  the  Subcarboniferous  Crinoidal  limestones.  Such  blanks  need  explana- 
tion ;  for  the  equivalent  fossiliferous  can  hardly  be  absent  from  the  whole  of 
a  continental  area. 

6.  The  inferior  value  of  plants  to  animals  as  tests  of  geological  age  of 
equivalency  is  generally  admitted.     It  appears  to  be  true  also  that  marine 
fossils  are  entitled  to  greater  weight  than  terrestrial  or  fresh-water  species 
excepting  the  fossil  Vertebrate.     But  the  evidence  from  Vertebrates  is  always 
surest  when  fortified  by  that  of  Invertebrates. 

The  difficulties  are  not  often  sources  of  final  doubt  when  the  conclusions 
are  based  on  the  general  range  of  animal  types  characterizing  an  era.  Should 
a  Trilobite  be  hereafter  discovered  in  any  Cretaceous  rocks  of  the  world,  it 
would  lead  no  one  to  suspect  those  rocks  to  be  Paleozoic,  because  the  asso- 
ciated species  would  be  sufficient  to  settle  the  question  of  age. 

Among  metamorphic  rocks,  the  outcrops  of  the  rock  should  be  followed 
into  the  region  of  feeble  metamorphism  where  traces  of  fossils  may  possibly 
be  found.  By  studying  the  relations  of  the  associated  rocks  as  to  bedding, 
and  proving  conform  ability  and  continuity,  the  discovery  of  a  few  fossils  in 
one  stratum  of  the  series  at  a  single  locality  may  settle  the  question  of  age 
approximately  for  a  whole  formation  hundreds  of  miles  in  length. 

SUBDIVISIONS  OF   GEOLOGICAL   TIME. 

General  basis  of  subdivisions.  —  In  view  of  the  principles  explained  in 
the  preceding  pages  it  follows  that  — 

1.  The  grander  divisions  of  geological  time  should  be  based,  in  a  com- 
prehensive way,  on  organic  progress,  independently  of  events  connected  with 
rock-making  and  disturbances  of  the  crust.  Examples  of  such  divisions 
are  those  of  the  four  primary  divisions,  the  Archaean,  Paleozoic,  Mesozoic, 
and  Cenozoic. 


SUBDIVISIONS   IN   GEOLOGICAL   HISTORY.  405 

2.  Subordinate  divisions  should  recognize  the  same  criterion,  but  should 
depend  for  their  limits,  as  far  as  practicable,  on  physical  breaks  or  events 
registered  in  the  rock-series,  and  on  abrupt  transitions  in  kinds  or  groups  of 
fossils.     Since  the  latter  are  dependent  on  physical  changes,  they  are  a  con- 
venient criterion  when  characterizing  large  areas. 

3.  When  subordinate  divisions  of  the  higher  grades  have  been  estab- 
lished on  any  continent,  or  part  of  a  continent,  these  divisions  should  be 
recognized  and  adopted  as  nearly  as  possible  in  the  study  of  other  regions, 
and  their  limits  determined  if  possible  by  means  of  the  fossils ;  for  only  in 
this  way  can  the  history  of  different  regions  be  brought  together  into  one  sys- 
tem.   For  example  :    the  Permian  period,  recognized  and  defined  in  European 
geological  history,    should  have  its  place  in  American  geological  history, 
however  intimately  the  beds  and  their  fossils  in  America  may  blend  with 
those  of  the  Carboniferous  period.     So  also  the  Devonian  of  Europe  should 
be  recognized  and  have  like  limits,  as  nearly  as  may  be,  in  the  Devonian 
of  America.     A  degree  of  fixedness  in  the  higher  subdivisions  and  their 
names  is  necessary  to  prevent  confusion  in  the  literature  of  the  science 
and  the  frustration  of  its  great  purpose, — the  production  of  a  comprehensive 
earth-history. 

4.  Inferior  subordinate  divisions  so  far  depend  on  local  conditions,  that 
those  of  different  continents,  and  even  of  distant  parts  of  the  same  continent, 
generally  require,  in  the  first  study  of  a  region,  special  designations  to  avoid 
assumptions  of  closer  relationships  or  equivalency  than  can  be  made  out. 
The  different  continents,  and  often  also  unlike  regions  of  the  same  continent, 
have  had  their  special  histories.     The  periods  and  epochs  of  America  and 
Europe  are  not  in  general  the  same  in  limits,  and  much  less  so  in  rocks.    The 
Devonian  subdivisions  are  different  on  the  two  continents  ;  and  it  is  far  from 
certain,  also,  that  the  commencement  assigned  to  the  Devonian  in  North 
America  is  synchronous  with  that  in  Europe.     In  the  Carboniferous,  Rep- 
tilian, and  Mammalian  eras  the  American  epochs  differ  from  the  European. 
There  is  much  diversity  between  the  subdivisions  in  New  York  and  those  of 
the  Mississippi  valley,  and  still  greater  between  these  and  the  subdivisions 
of  the  Pacific  slope  and  border.     Even  in  Pennsylvania  the  formations  fail 
of  many  of  the  subdivisions  that  are  prominent  in  New  York. 

Hence  in  the  study  of  a  new  region  it  is  necessary  at  the  outset  to  make 
arbitrary  subdivisions  of  its  formations,  such  as  may  seem  most  convenient 
and  natural,  and  give  them  local  names.  These  names  have  at  first  only  a 
note-book  value.  When  the  relations  of  the  beds  to  those  recognized  in 
other  regions  have  been  ascertained  through  fossils,  the  facts  begin  to  take 
their  places  in  the  general  geological  history  of  the  country ;  and  should  the 
correlation  be  complete,  the  local  names  may  give  way  to  those  generally 
accepted  elsewhere. 

It  is  of  the  highest  importance  to  remember  that  state  boundaries  are 
only  political  limits,  and  not,  ordinarily,  at  least  in  America,  true  geographi- 
cal or  geological  limits ;  and  if  the  subdivisions  of  one  state  which  have 


406  HISTORICAL   GEOLOGY. 

already  received  local  names  extend  into  the  adjoining,  the  introduction  of 
new  names  in  the  latter  is  a  wrong  to  the  science. 

5.  In  all  cases,  the  characteristics  of  the  species  and  the  beds  should  be 
carefully  scrutinized,  lest  abruptness  due  to  local  migrations  (as  those  caused 
by  slight  changes  of  depth  or  currents  and  kinds  of  sea-bottom)  should  be 
mistaken  for  abruptness  of  real  importance. 

Physical  and  Organic  Breaks.  —  Prominent  among  the  events  influencing 
the  rock-structure  and  life  of  a  continent  is  that  of  mountain-making.  The 
Appalachian  Mountains  stand  as  a  grand  time-boundary  between  the  Paleozoic 
aeon  and  the  Mesozoic ;  and  cotemporaneous  orographic  movements  make  a 
like  limit  in  European  geology.  Moreover,  it  was  attended  by  the  most 
remarkable  of  organic  breaks.  The  Taconic  mountains  mark  the  close  of 
the  Lower  Silurian,  an  epoch  of  abrupt  change  in  North  America;  and 
parallel  disturbances  occurred  in  Britain  and  Europe.  The  Laramide  or 
post-Cretaceous  mountain  system  along  the  Kocky  Mountains  is  another 
such  boundary  for  America,  separating  Mesozoic  and  Cenozoic  time,  though 
not  as  complete  in  the  attendant  organic  break  as  in  the  physical.  But  it  so 
happens  that  no  corresponding  event  occurred  at  this  time  in  Europe,  the 
orographic  movements  most  nearly  synchronous  taking  place  after  the  com- 
mencement of  Cenozoic  time.  Nevertheless,  th«  organic  break  at  the  close 
of  the  Cretaceous  period  is  even  greater  for  Europe  than  for  America. 
Such  a  fact  seems  to  show  that  there  was  some  other  catastrophic  event 
concerned ;  but  its  nature  is  yet  to  be  studied  out. 

Part  of  the  breaks  referred  to  above  were  limited  in  their  effects  to 
the  hemisphere  including  America,  Europe,  northern  and  middle  Asia,  and 
northern  Africa.  The  opposite  hemisphere,  that  of  India,  Australia,  and 
South  Africa,  has  been  more  or  less  independent,  although  the  two  were  alike 
in  many  characteristics ;  and  owing  to  this,  the  boundary  closing  Paleozoic 
time,  so  strongly  marked  in  the  geological  history  of  Europe  and  America, 
cannot  be  satisfactorily  denned  in  the  latter.  The  coal  period  is  of  later 
date  than  that  of  Europe  and  America,  it  occurring  in  the  Permian,  and  the 
Permian  period  blends  with  the  Triassic. 

Such  orographic  time-boundaries  are  registered  not  only  in  the  rocks  that 
are  upturned,  but  also  in  unconformabilities  between  them  and  the  succeed- 
ing rocks.  It  is  important  to  note,  however,  as  already  stated,  that  the 
unconformability  exists  only  in  upturned  regions.  A  short  distance  away,  the 
succeeding  beds  will  be  found  lying  conformably  over  the  same  kinds  that 
are  upturned  in  the  mountains ;  moreover,  the  organic  break  there  may  be 
less  pronounced,  and  in  more  distant  regions  it  may  fail  altogether.  The 
unconformability  is,  however,  none  the  less  important  as  a  time-boundary, 
for  orographic  upturnings  have  been  events  of  great  geographical  extent 
after  long  ages  of  preparation. 

The  Subdivisions.  —  The  several  grades  of  subdivisions  of  geological 
time  are  named  (1)  ^Eons,  (2)  Eras,  (3)  Periods,  (4)  Epochs;  and  the 
corresponding  terms  applied  to  the  formations  are  Series,  Systems,  Groups, 


SUBDIVISIONS   IN   GEOLOGICAL   HISTORY.  407 

Stages.  For  intermediate  divisions  sub  is  prefixed  to  the  name  of  the 
division  next  above.  Still  lower  subdivisions  are  termed  zones,  and  receive 
special  designations  from  a  characteristic  fossil.  Subdivisions  of  zones, 
corresponding  to  the  vertical  distribution  of  species,  have  been  recently 
called  hemerce,  from  the  Greek  for  day.  In  place  of  any  of  the  above 
terms,  the  word  time  may  be  used  in  its  usual  sense  whenever  it  is  thought 
convenient.  It  is  substituted  beyond  for  the  word  ceon. 

I.  ARCHAEAN  TIME.  —  The  beginning  of  Archaean  time  was  without  life ; 
but  before  it  closed  conditions  had  been  reached  that  admitted  of  the  exist- 
ence of  protophytic  and  protozoic  life. 

II.  PALEOZOIC  TIME.  —  Characterized  by  the  more  ancient  kinds  of  life, 
closing  with  the  period  of  the  great  Coal  formations  of  Europe  and  America, 
so  named  from  TroAaio's,  ancient,  and  £wrj,  life. 

III.  MESOZOIC  TIME.  —  The  life  of  mediaeval  types  or  kinds ;  closes  with 
the  period  of  the  Chalk  or   Cretaceous   formation,  so  named  from  /x«ros, 
middle,  and  ^OM/. 

IV.  CENOZOIC  TIME.  —  The  life  of  more  modern  types,  continuing  to  the 
present  time,  so  named  from  KCUVOS,  recent,  and  £a>rj. 

The  term  Paleozoic  was  proposed  by  Sedgwick  in  1838,  and  preferred  and  adopted  by 
Murchison  the  same  year  in  place  of  his  own  name  Protozoic,  it  "involving  no  theory." 
For  the  terms  Mesozoic  and  Cenozoic,  and  the  upper  limit  of  the  Paleozoic,  the  science  is 
indebted  to  Professor  John  Phillips,  of  Oxford,  England.  Cenozoic  is  sometimes  written 
Cainozoic  or  Kainozoic.  But  in  English,  derivatives  from  the  Greek  diphthong  at  become 
ce  or  e,  as  in  Ethiopia,  Eolian,  Egypt,  Etna,  ether,  hematite  ;  and  K  becomes  c,  as  in  center, 
circle,  calyx,  camel,  and  multitudes  of  other  words.  Lyell's  names  for  divisions  of  the 
Tertiary,  namely,  Eocene,  Miocene,  Pliocene  —  are  examples  of  both  cases,  the  ce  in 
each  being  K<U  in  Greek. 

The  following  table  contains  some  of  the  subdivisions  of  inferior  grade  : 

I.    ARCHAEAN  TIME. 

There  are  the  two  divisions,  the  Azoic  and  the  ARCHEOZOIC,  but  they  are 
not  distinguishable  in  the  rocks.  The  rocks  have  been  divided  into  — 

1.  LAURENTIAN. 

2.  HURONIAN. 

II.    PALEOZOIC   TIME. 
1.   Eopaleozoic  Section. 

1.  CAMBRIAN,  OR  CAMBRIC,  ERA. 

1.  Lower  Cambrian,  or  Georgian  Period. 

2.  Middle  Cambrian,  or  Acadian  Period. 

3.  Upper  Cambrian,  or  Potsdam  Period. 

2.  LOWER  SILURIAN,  OR  LOWER  SILURIC,  ERA. 

1.  Canadian  Period. 

2.  Trenton  Period. 


408  HISTORICAL   GEOLOGY. 

2.    Neopaleozoic  Section. 

1.  UPPER  SILURIAN,  OR  UPPER  SILURIC,  ERA. 

1.  Niagara  Period. 

2.  Onondaga  Period. 

3.  Lower  Helderberg  Period. 

2.  DEVONIAN,  OR  DEVONIC,  ERA. 

1.  Oriskany  Period. 

2.  Corniferous  Period. 

3.  Middle  Devonian,  or  Hamilton,  Period. 

4.  Upper  Devonian  Period. 

3.  CARBONIC  ERA. 

1.  Subearboniferous  Period. 

2.  Carboniferous  Period. 

3.  Permian  Period. 

III.  MESOZOIC  TIME. 

1.  Triassic  Period. 

2.  Jurassic  Period. 

3.  Cretaceous,  or  Cretacic,  Period. 

IV.  CENOZOIC  TIME. 

1.  TERTIARY  ERA. 

2.  QUATERNARY  ERA. 

European  geologists,  at  meetings  of  the  International  Congress  of  Geologists,  have 
decided  to  make  the  names  of  the  higher  subdivisions  of  the  eras  end  in  ic. 

In  early  geologic  science,  the  oldest  system  of  rocks  recognized  was  called  the 
Primary  or  Primitive  system,  and  it  comprised  granite,  gneiss,  mica  schist,  and  all 
other  related  crystalline  rocks  ;  and  the  more  schistose  kinds,  like  mica  schist,  chlorite 
schist,  hornblende  schist,  were  made  the  newer  of  the  series.  The  terms  "Fundamental 
gneiss,"  in  English,  and  "Urgneiss,"  German,  are  relics  of  this  beginning  period. 

Under  the  same  geological  scheme  —  that  of  Werner  —  the  second  division  was  called 
the  Transition  rocks.  It  embraced  the  semi-crystalline  schists,  and  slates  or  argillyte,  along 
with  hard  gritty  rocks  called  gray-wacke,  and  some  limestones  which  were  much  upturned 
and  thus  were  seemingly  distinct  from  the  ordinary  fossiliferous  strata,  or  the  so-called 
"  Secondary  "  rocks.  Their  partly  semi-crystalline  texture  and  their  upturned  condition 
were  regarded  as  evidence  of  their  being  older  than  and  separate  from  "  Secondary  " 
rocks ;  and  their  imperfectly  crystalline  or  uncrystalline  state,  that  they  were  younger 
than  the  Primary  rocks. 

The  idea  that  gneiss  and  mica  schist  are  always  "  Primary  "  or  Archsean  rocks,  that 
grade  of  crystallization  is  a  safe  mark  of  relative  age,  was  shown  to  be  false  by  Lyell 
(Principles,  1830-33),  who,  with  De  la  Beche  (1834),  rejected  all  Wernerian  errors. 
Lyell  went  so  far  as  to  hold  —  as  a  table  in  the  third  volume  of  his  Principles  (1833, 
p.  387)  shows — that  crystalline  or  metamorphic  schists  may  occur  in  all  the  formations, 
from  the  earliest  to  the  latest. 


SUBDIVISIONS    IN    GEOLOGICAL    HISTORY. 


409 


The  general  facts  in  the  progress  of  life  on  the  globe  are  illustrated  in 
the  annexed  diagram :  — 

351. 

ANIMALS.  PLANTS. 


Quaternary 

Tertiary,  or  Era  of  Mammals 

Mesozoic,  or  Era  of  Reptiles 

Carbonic 


Devonian 

Upper  Silurian 

Lower  Silurian , 

Cambrian.. . 


Archa3an 


The  horizontal  bands  represent  the  divisions  of  time ;  the  vertical  cor- 
respond to  different  groups  of  animals  and  plants.  The  lower  end  of  each 
vertical  band  marks  the  point  in  geological  time  when,  according  to  present 
knowledge  from  fossils,  the  type  it  represents  began ;  and  the  varying  width 
in  the  same  bands  indicates  the  greater  or  less  expansion  of  the  type.  The 
following  are  the  points  the  diagram  illustrates  :  — 

According  to  present  facts  from  fossils,  Radiates  began  in  the  Cambrian, 
and  have  continued  till  now,  rather  increasing  throughout  the  ages. 

Mollusks  had  their  beginning  in  the  Cambrian,  and  continued  increasing 
to  the  era  of  Keptiles:  they  then  passed  their  maximum  (as  indicated  in 
the  figure). 

Articulates  commenced  in  the  early  Cambrian ;  and,  excluding  the  tribe 
to  which  the  Trilobite  belongs,  they  continued  expanding  in  numbers  and 
grade  to  the  present  time. 

Fishes  began  in  the  Lower  Silurian,  were  very  abundant  and  of  great 
size  in  the  Devonian,  and  continued  on,  becoming  further  diversified  in 
later  periods. 

Amphibians  began  in  the  Carbonic,  and  reached  their  maximum  in  the 
early  part  of  the  Reptilian  era. 

Reptiles  began  in  the  Permian  period  of  the  Carbonic,  and  had  their 
maximum  in  the  Reptilian  era  or  Mesozoic  time. 

Mammals  began  in  the  Reptilian  era,  and  became  the  highest  of  species 
in  the  Mammalian  era  or  Cenozoic  time. 

Sea-weeds  (or  Algse)  were  the  earliest  plants  of  the  globe,  probably  pre- 
ceding animal  life.  Acrogens  and  Conifers  began  in  the  Upper  Silurian  and 
possibly  earlier.  The  Acrogens  had  their  greatest  expansion  in  the  era  of 
Coal-plants,  in  which  they  occurred  with  Conifers.  Cycads  began  in  the 
Devonian,  and  had  their  greatest  expansion  in  the  Reptilian  era.  Angio- 
sperms  or  Dicotyledons  began  in  the  closing  period  of  the  Reptilian  era, 
and  expanded,  along  with  Palms,  through  the  era  of  Mammals. 


410 


HISTORICAL   GEOLOGY. 
352. 


Archaean. 


v  v  v  v  v 
vvvvvvvvvvvv 


Permian. 


Upper  Coal-measures. 


Lower  Coal-measures. 

Millstone  Grit. 

Upper,  or  Mauch  Chunk. 

Lower,  or  Pocono. 

Chemung  and  Catskill. 
Portage,  Genesee. 

Hamilton. 
Marcellus. 
Corniferous. 

(  Schoharie  and 
I  Cauda-galli. 
Oriskany. 

Lower  Helderberg. 
Salina  and  Water  Lime. 
Niagara. 

Clinton. 

Medina. 

Hudson. 

Utica. 

Trenton. 

Cbazy. 

Calciferous. 
Potsdam. 

Acadian. 
Georgian. 

Archaean. 


SUBDIVISIONS    IN    GEOLOGICAL   HISTORY. 
353. 


Recent. 


411 


f  Upper  or  White 

Chalk. 
Upper  Cretaceous. <  Lower  Chalk,  and 

Marl. 
Upper  GreenHand. 


Lower  Cretaceous  or  Neocomian,  in 
cluding  the  Wealden. 


Keuper. 

MiiBchelkalk. 

Bunteraandatein. 


Agassiz,  first  at  Neufcha"tel,  in  1841,  in  a  Discours  sur  la  Succession  et  le 
Developpement  des  Etres  organists,  and  later  in  his  Principles  of  Zoology,  1848, 
distinguished  Paleozoic  time,  as  that  of  the  Reign  of  Fishes  ("le  Kegne  des 
Poissons  ") ;  Mesozoic  time,  as  that  of  the  Keign  of  Keptiles ;  and  Cenozoic 
time,  as  that  of  the  Keign  of  Mammals. 

Inferior  Subdivisions.  —  The  subdivisions  under  the  eras,  —  the  periods, 
and  epochs,  —  vary,  as  has  been  stated,  in  different  countries.  The  table 
(Fig.  352)  presents  a  general  view  of  those  of  eastern  North  America,  so 
far  as  the  Paleozoic  is  concerned,  —  the  Silurian,  Devonian,  and  Carbonic 
being  well  represented  on  the  continent.  The  rest  of  the  series  (Fig.  353)  is 
partly  from  European  geology,  where  the  system  is  well  represented. 

In  this  Manual,  American  geology  is  in  general  first  considered;  and 
afterward  such  further  illustrations  are  drawn  from  other  continents  as  are 
necessary  for  comprehensive  views  and  generalizations. 

The  subdivisions,  as  the  table  shows,  are  named,  for  the  most  part,  from 
the  locality  or  region  where  the  rocks  are  well  displayed.  Owing  to  condi- 
tions explained  beyond,  the  subdivisions  of  the  American  Paleozoic  series  are 


412 


HISTORICAL   GEOLOGY. 


more  numerous  and  more  trenchantly  distinct  in  the  state  of  New  York  than 
in  most  other  parts  of  the  continent ;  and,  moreover,  the  rocks  of  the  state 
were  studied  in  detail  and  described  by  the  geologists  of  the  New  York  Sur- 
vey between  the  years  of  1836  to  1842,  the  systematizing  period  in  geological 
science.  For  these  reasons,  but  especially  the  latter,  a  number  of  the  sub- 
divisions bear  the  names  of  New  York  localities. 

The  following  map  of  the  United  States  east  of  the  Rocky  Mountains 
exhibits  the  geographical  distribution  of  the  rocks  of  the  several  ages; 
that  is,  the  regions  over  which  they  are  severally  the  surface-rocks. 

354. 


GEOLOGICAL  MAP 

OF  PART  OF 

NORTH  AMERICA 


BRIEF   REVIEW   OF   THE   SYSTEM    OF   LIFE.  413 

The  map  is  from  the  geological  chart  of  C.  H.  Hitchcock,  with  changes 
from  later  publications.  The  blank  area  on  the  eastern  border  comprises 
Archaean,  Cambrian,  and  Lower  Silurian  rocks,  not  yet  having  their  limits 
denned. 

The  progress  of  the  life  of  the  globe  is  one  of  the  two  great  subjects  that 
come  before  the  student,  in  the  following  part  of  this  Manual,  treating  of 
HISTORICAL  GEOLOGY.  By  way  of  introduction  to  it,  a  short  chapter  on  its 
system  of  structures  is  here  introduced. 

BEIEF  KEVIEW  OF  THE   SYSTEM  OF  LIFE. 

GENERAL  CONSIDERATIONS. 

1.  Life.  —  Some  of  the  distinctions  between  a  living  organism  and  inorganic  or  min- 
eral substances  have  been  mentioned.    Recapitulated,  with  additions,  they  are  :  — 

(1)  The  living  being  has,  as  the  fundamental  element  of  its  structures,  visible  cells, 
containing  fluids  or  plastic  material. 

(2)  It  enlarges  by  means  of  imbibed  nutriment,  through  a  process  of  development ; 
and  not  by  mere  accretion  or  crystallization. 

(3)  It  has  the  faculty  of  converting  nutriment  into  the  various  chemical  compounds 
essential  to  its  constitution,  and  of  continuing  this  process  of  assimilation  as  long  as  the 
functions  of  life  continue  ;  and  it  loses  this  chemical  power  when  life  ceases. 

(4)  It  passes  through  successive  stages  in  structure,  and  in  chemistry,  from  the  simple 
germ  to  a  more  or  less  complex  adult  stage,  and  finally  evolves  other  germs  for  the  contin- 
uance of  the  species  ;  instead  of  being  equally  perfect  and  equally  simple  in  all  its  stages, 
and  essentially  germless. 

There  is,  therefore,  in  the  living  organism,  something  besides  mere  physical  forces,  or 
the  chemistry  of  dead  nature  —  something  that  ceases  to  be  when  life  ceases.  There  is  a 
vital  condition,  in  which  molecules  have  powers  that  lead  to  resulting  seed-bearing  struc- 
tures, widely  different  from  those  of  inorganic  nature,  and  standing  on  altogether  a  higher 
level.  There  is  a  power  of  development,  an  architectonic  power,  that  not  only  exalts 
chemical  results,  but  evolves  a  diversity  of  parts  and  structures,  and  a  heritage  of  ancestral 
qualities,  of  which  the  laws  of  material  nature  give  no  explanation. 

2.  Vegetable  and  Animal  life.  — The  vegetable  and  animal  kingdoms  are  the  mutu- 
ally dependent  sides  or  parts  of  one  system  of  life.     The  following  are  some  of  their  dis- 
tinctive characteristics :  — 

(1)  Plants  take  nutriment  into  the  tissues  by  absorption  ;  animals  have  a  mouth,  and 
receive  food  into  a  sac  or  stomach.     Exceptions  to  this  feature  occur  in  animal  life  only 
in  the  lowest  microscopic  forms  and  certain  parasitic  kinds ;  and  the  most  of  these  extem- 
porize a  mouth  and  stomach  whenever  any  particle  of  food  comes  in  contact  with  the  outer 
surface,  so  that  even  here  the  food  is  digested  in  an  interior  cavity.     Certain  insectivo- 
rous plants  "digest"  animal  material,  but  the  process  is  not  necessary  to  growth,  with 
small  exceptions. 

(2)  Plants  find  nutriment  in  carbonic  acid,  appropriate  the  carbon,  and  set  free  oxygen, 
a  gas  essential  to  animal  life ;  animals  use  oxygen  in  respiration,  and  set  free  carbonic 
acid,  a  gas  essential  to  vegetable  life.     (The  amount  of  carbonic  acid  given  out  by  plants 
in  respiration  is  too  small  to  need  consideration  here.) 

(3)  Plants  take  inorganic  material  as  food,  and  turn  it  into  organic ;  animals  take 
this  organic  material  thus  prepared  (plants),  or  other  organic  materials  made  from  it  (ani- 
mals), finding  no  nutriment  in  inorganic  matter. 


414  HISTORICAL   GEOLOGY. 

(4)  The  Vegetable  Kingdom  is  a  provision  for  the  storing  away  or  magazining  of  force 
for  the  Animal  Kingdom.    This  force  is  acquired  through  the  sun's  influence  or  forces  acting 
on  the  plant,  and  so  promoting  growth  ;  mineral  matter  is  thereby  carried  up  to  a  higher 
grade  of  composition,  that  of  starch,  gluten,  vegetable  fiber  and  other  products,  and  in 
this  there  is  a  concentration  or  accumulation  of  force.     To  this  stored  force  animals  go  for 
growth  and  development ;  and,  moreover,  the  grade  of  composition  is  thus  carried  yet 
higher,  to  muscle  and  nerve  ;  and  this  is  a  magazining  of  force  in  a  still  more  concentrated 
or  condensed  state. 

(5)  Plants,  of  some  minute  kinds,  and  the  spores  of  some  larger  species  (some  Algae) 
have  locomotion,  or  a  degree  of  contractility  in  certain  parts  that  corresponds  to  an  infini- 
tesimal amount  of  mechanical  power ;  but  the  locomotive  spores,  as  they  develop,  become 
fixed,  like  the  plants  from  ordinary  seeds,  and  no  increase  of  mechanical  power  accompa- 
nies vegetable  development.     In  animal  development  from  the  germ,  on  the  contrary, 
there  is  always  an  increase  of  power  —  an  increase,  in  all,  of  muscular  (mechanical) 
power,  and,  in  the  case  of  species  above  the  lower  grade,  of  psychical  and  intellectual 
power,  —  until  an  ant,  for  example,  becomes  a  one-ant  power,  a  horse  a  one-horse  power. 
Whence,  an  animal  is  a  self-propagating  piece  of  enginery,  of  various  power  according 
to  the  species. 

(6)  In  the  plant,  the  root  grows  downward  (or  c?ar£-ward)  and  the  stem  upward  (or 
Zi0to-ward),  and  there  is  thus  the  up-and-down  polarity  of  growth  —  the  higher  develop- 
ments, those  connected  with  the  fruit,  taking  place  above,  or  in  the  light.     In  the  animal, 
there  is  an  antero-posterior  polarity  of  power  as  well  as  growth  —  the  head,  which  is  the 
seat  of  the  chief  nervous  mass  and  of  the  senses,  and  the  locus  of  the  mouth,  making  the 
anterior  extremity.     Consequently,  there  is  in  animals  a  connection  between  grade  and 
the  greater  or  less  dominance  and  perfection  of  the  head  extremity.     An  animal,  as  its 
ordinary  movements  manifest,  is  preeminently  a  go-ahead  thing.      Even  the   inferior 
stationary  species,  like  the  Polyp,  show  it  in  the  superior  power  that  belongs  to  the 
mouth  extremity. 

(7)  Plants  have  no  consciousness  of  self,  or  of  other  existences ;  animals  are  con- 
scious of  an  outer  world,  and  even  the  lowest  show  it  by  avoiding  obstacles. 

From  the  above  diverse  characteristics  of  plants  and  animals,  it  follows  that,  however 
alike  chemically  are  the  germs  of  the  two,  they  must  still  be,  in  their  chemical  nature, 
fundamentally  different. 

ANIMAL  KINGDOM. 

The  most  prominent  subdivisions  of  the  Animal  Kingdom  are :  — 

I.  VERTEBRATES  ;  II.  INVERTEBRATES. 

These  subdivisions  are  based  on  the  presence  in  the  former  alone  of  a  vertebral 
column,  with  a  bone-sheathed  cavity  along  the  dorsal  side  of  the  column  for  the  great 
nervous  cord.  This  vertebral  column  in  the  embryo-stage  and  in  many  adult  fishes  is  a 
cartilaginous  cord,  called  the  notochord  (from  the  Greek  for  back  and  a  gut  chord  of  a 
stringed  instrument),  situated  below  and  parallel  with  the  spinal  cord  of  nerve  ;  out  of  it, 
as  development  and  ossification  proceed,  the  vertebral  column  is  produced.  In  the  sheath 
of  the  spinal  nervous  cord,  the  dorsal  spinous  processes  of  the  vertebrae  are  produced, 
which  more  or  less  inclose  the  cord.  The  Invertebrates,  besides  having  no  vertebral 
column  within,  have  the  chief  nervous  cord  ventral  in  position  and  below  the  intestinal 
canal  instead  of  dorsal. 

The  Vertebrates  include,  beginning  with  the  highest :  — 

MAMMALS  REPTILES  FISHES 

BIRDS  AMPHIBIANS  LEPTOCARDIANS 

All  other  species  are  Invertebrates. 


BRIEF    REVIEW   OF  THE  SYSTEM  OF  LIFE.  415 


VERTEBRATES. 

The  more  prominent  characteristics  of  the  six  classes  of  Vertebrates  are  the  fol- 
lowing :  — 

1.   Mammals. 

Species  that  suckle  their  young ;  breathe  by  means  of  lungs ;  have  a  heart  of  four 
cavities.  There  are  three  prominent  subdivisions:  (1)  The  true  Viviparous,  as  Man, 
ordinary  Quadrupeds,  Bats,  Whales,  Seals.  (2)  The  Semi-oviparous,  the  young  of  which 
are  more  immature  at  birth  (the  birth,  therefore,  intermediate  between  the  oviparous  and 
viviparous),  and  which  are  passed  into  a  pouch  where  they  are  suckled  until  maturity  :  as 
the  Marsupials,  of  which  the  Kangaroo  of  Australia  and  the  Opossum  of  North  America 
are  examples.  (3)  The  Oviparous,  or  Monotremes,  as  the  Ornithorhynchus  of  Australia 
and  Tasmania,  and  the  Echidnse  of  Australia,  Tasmania,  and  New  Guinea,  which  produce 
true  eggs.  The  Ornithorhynchus,  or  Duckbill,  has  the  bill  of  the  Duck,  and  lives  along 
streams  in  holes  entered  below  the  level  of  the  water.  It  has  the  bones  that  in  Marsupials 
support  the  pouch,  but  not  the  pouch. 

2.   Birds. 

Oviparous ;  breathing  by  lungs ;  heart  of  four  cavities ;  covered  with  feathers,  and 
having  wings  mostly  adapted  for  flying.  All  existing  birds  have  bills  without  teeth  ;  but 
geological  discovery  has  made  known  the  existence  in  Mesozoic  time  of  birds  with  a  full 
set  of  teeth. 

3.   Reptiles. 

Oviparous;  breathing  by  lungs  ;  a  heart  of  three  or  four  cavities;  naked  or  covered 
with  scales :  as  Crocodiles,  Lizards,  Turtles,  Snakes. 

4.    Amphibians. 

Oviparous ;  breathing  when  young  by  gills,  afterward  by  both  gills  and  lungs,  or  by 
lungs  alone ;  a  heart  of  three  cavities  ;  naked  or  covered  with  scales :  as  Frogs,  which  lose 
the  tail  as  well  as  gills  on  becoming  adults  ;  and  Salamanders,  the  tailed  (or  lizard-like) 
Amphibians.  The  modern  species  are  naked-skinned  and  often  toothless;  but  many 
ancient  kinds  had  scales  like  Reptiles  and  stout  teeth. 

5.   Fishes. 

Usually  oviparous  ;  heart  usually  of  two  cavities  ;  breathing  by  gills,  which  take  air 
from  the  water,  and  are  situated  in  front  of  one  or  more  openings  in  the  sides  of  the  throat 
that  let  out  water  which  enters  by  the  mouth  ;  skin  naked,  or  covered  with  scales  or  bony 
plates.  Locomotion  chiefly  a  process  of  sculling  by  means  of  the  posterior  or  caudal 
extremity  of  the  body. 

Under  Fishes  there  are  the  following  prominent  divisions  :  — 

PAL^ICHTHYES,  or  Fishes  of  ancient  type,  including  the  Sharks  and  Gars,  charac- 
terized by  a  heart  with  the  arterial  bulb  contractile  and  the  intestine  having  a  valve 
between  it  and  the  stomach,  both  characters  showing  relations  to  the  Amphibians.  The 
three  grand  divisions  are :  — 

1.  Selachians.  —  The  group  includes  the  Sharks  (Fig.  355)  and  Rays  —  Fishes  having 
a  cartilaginous  skeleton  ;  usually  several  gill  openings  or  slits  (g}\  no  gill-cover,  and  gills 
attached  to  the  skin  by  the  outer  margin  instead  of  being  free  ;  embryo  with  deciduous 
external  gills;  no  air-bladder;  usually  no  proper  scales,  but  a  rough  skin  (shagreen). 
The  ordinary  Sharks  have  the  mouth  underneath  and  separate  from  the  nostrils,  with  the 
teeth  sharp-edged  (Figs.  358,  359,  360) ;  another  group,  the  Hybodonts,  have  the  teeth  of 


416 


HISTORICAL  GEOLOGY. 


similar  form  to  the  preceding,  but  round  or  blunt-edged  (Figs.  361,  362)  ;  another,  the 
Cestracionts  (Fig.  357),  an  ancient  type,  of  which  only  one  genus  now  exists,  has  a  pave- 
ment (Fig.  363)  of  small  bony  pieces  (Figs.  364,  365)  in  the  mouth  (for  grinding  up  shell- 
fish, etc.),  and  a  series  of  smaller  teeth  at  the  margin,  with  the  mouth  and  cavities  of  the 
nostrils  confluent.  Many  ancient  Sharks,  like  a  few  of  the  modern,  had  large  spines 
connected  with,  and  usually  along  the  anterior  margin  of,  the  fins  (Figs.  355,  356).  As 
these  fishes  have  the  vertebral  column  imperfectly  ossified  when  not  cartilaginous,  the 
fossils  are  mostly  teeth,  spines,  fragile  vertebrae,  and  occasionally  shagreen. 

In  the  lowest  group,  the  Chimcerids,  there  is  a  cartilaginous  notochord  multif  licately 
subdivided,  the  sheath  of  which  is  partly  ossified.  The  species  have  a  few  very  large 
teeth,  and  a  single  gill-opening,  which  is  covered  by  a  fold  in  the  skin.  To  this  group 
are  referred  the  Acanthodians,  which  were  formerly  supposed  to  be  Ganoids.  They 
have  very  small  rhombic  scales,  a  spine  along  the  front  margin  of  the  fins,  and  are 
apparently  without  teeth. 

355-365. 


SELACHIANS.  —  Fig.  355,  Spinax  Blainvillii  (x  £);  356,  Spine  of  anterior  dorsal  fin,  natural  size;  357,  Cea- 
tracion  Philippi  (x  |) ;  358,  Tooth  of  Lamna  elegans;  359,  id.  Carcharodon  angustidens;  360,  id.  Noti- 
dauus  primigenius;  361,  id.  Hybodus  minor;  362,  id.  Hyb.  plicatilis;  363,  Mouth  of  Cestracion,  showing 
pavement-teeth  of  lower  jaw;  364,  Tooth  of  Acrodus  minimus;  365,  id.  Acrodus  nobilis. 


2.  Ganoids  or  Gars  (Figs.  366  and  375).  —  The  Ganoids  have  the  skeleton  cartilagi- 
nous in  the  earlier  kinds,  but  more  or  less  ossified  in  the  later  and  in  the  few  modern 
species  ;  one  gill-opening ;  a  gill-cover,  and  gills  free  ;  an  air-bladder,  having  a  pneu- 
matic duct;  embryo  sometimes  with  external  gills.  Skin  covered  commonly  with 
thick  bony  scales,  like  Reptiles  or  ancient  Amphibians  (whence  ganoid,  from  the  Greek 
7<i»'os,  shining},  or  with  bony  plates,  somewhat  turtle-like  ;  scales  often  rhombic  and  set 
together  like  tile  (Figs.  366,  375)  ;  and  interlocked  by  projecting  points  (Figs.  367,  368); 
sometimes  cycloid  and  imbricate.  Tails  of  ancient  species  vertebrated  or  heterocerc,al,  like 


BRIEF   REVIEW    OF   THE    SYSTEM   OF   LIFE. 


417 


the  Sharks  (Fig.  375),  but  non-vertebrated  or  homocercal  in  many  later  kinds  (Fig.  366), 
except  in  the  embryonic  state.  Teeth  (Figs.  372,  373)  labyrinthine  in  interior  structure 
(Fig.  374,  a  cross-section),  a  feature  which  is  more  strongly  marked  in  the  teeth  of  ancient 
Amphibians  (the  Labyrinthodonts) ,  which  geologically  succeeded  to  the  Ganoids. 

The  Ganoid  tribe  includes  :  — 

The  Placoderms,  an  aberrant  type,  having  the  head  and  anterior  part  of  the  body 
covered  with  a  shield  made  up  of  plates,  as  represented  in  figures  of  Pteraspids,  Cepha- 
laspids,  Asterolepids,  etc.,  on  pages  566,  624.  The  posterior  part  of  the  body  has  scales, 
which  admit  of  free  movement  for  sculling  locomotion.  The  pectoral  fins  are  large  arms 
in  the  Asterolepids,  fitted  apparently  for  crawling  over  muddy  surfaces  left  by  the  retreats 
ing  tide. 

366-374. 


GANOIDS  (excepting  369,  370).  — Fig.  366,  Tail  of  Thrissops  (x  £) ;  367,  Scales  of  Chirolepis  Traillii  (x  12) ; 
368,  id.  PalaeoniscuB  lepidurus  (x  6) ;  368  a,  under-view  of  same;  369,  Scale  of  a  Cycloid;  370,  id.  of  a 
Ctenoid;  371,  part  of  pavement-teeth  of  Gyrodus  umbilicus;  372,  Tooth  of  Lepidosteus;  373,  id.  of  a 
Cricodus;  374,  Section  of  tooth  of  Lepidosteus' osseus. 

The  Crossopterygians,  or  those  having  in  the  pectoral  fin,  like  many  Dipnoi,  a  thick- 
ened finger-like  axis,  with  reference  to  which  the  rest  of  the  fin  is  like  a  fringe,  and 
thence  the  name  of  the  group.  (Sthenopterygians,  referring  to  the  strengthened  axis  of 
the  fin,  would  be  better.)  Holoptychius,  Onychodus,  Glyptolepis,  Rhizodus,  Osteolepis, 
are  some  of  the  ancient  genera ;  and  Polypterus,  of  the  Upper  Nile,  is  a  related  genus. 


,    375. 


Palseoniscus  Freieslebeni  (x  J),  Permian. 

The  Palceoniscoids,  in  which  the  pectoral  fins  have  no  thickened  axis,  besides  other 
peculiarities,  as  in  Palaeoniscus  (Fig.  375),  Chirolepis,  Eurynotus,  etc. 

The  Pycnodonts,  having  the  palate  paved  with  blunt  rounded  molar-like  teeth,  as  in 
Pycnodus,  Gyrodus  (Fig.  371),  etc. 

3.  Dipnoans  or  Lung-fishes.  —  These  fishes,  of  which  the  species  of  Lepidosiren  and 
Ceratodus  are  living  representatives,  have  both  gills  and  lungs,  the  air-bladder  being 
cellular,  so  as  to  have  functional  value  as  a  lung  —  a  characteristic  that  enables  the 
DANA'S  MANUAL  —  27 


418  HISTORICAL   GEOLOGY. 

living  Ceratodus  to  survive  in  the  muddy  pools  of  dried-up  streams  in  Australia.  The 
pectoral  fins  are  a  pair  of  slender  filaments  in  Lepidosiren  ;  thickened  paddle-shaped  fins 
with  a  jointed  axis  in  Ceratodus,  and  have  a  thickened  axis  in  Phaneropleuron  and  other 
ancient  genera. 

TELEOSTS. — The  Teleosts  include  nearly  all  of  the  modern  fishes  except  the  Sharks 
and  Rays  and  the  few  existing  Ganoids.  They  are  closely  allied  to  the  Ganoids,  through 
the  existing  Amia  and  related  forms.  They  have  a  bony  skeleton,  as  implied  in  the  name 
(from  rAeos,  perfect,  drrtov,  bone) ;  and  the  gills  are  free.  In  the  absence  of  a  valve 
between  the  intestine  and  stomach  they  are  unlike  the  Ganoids  and  Sharks  and  inferior 
to  them  in  type  of  structure.  The  body  usually  has  scales,  which  are  either  cycloid 
(Fig.  369),  or  ctenoid  (Fig.  370),  the  latter  term  referring  to  the  toothed  or  spinous 
margin,  and  coming  from  the  Greek  for  comb  ;  but  in  some  kinds  there  are  bony  plates. 

CYCLOSTOMES  (Marsipobranchs)  or  Lampreys,  etc.,  having  a  simple  cartilaginous  noto- 
chord  ;  no  jaws ;  mouth  a  circular  opening  for  suction,  usually  with  conical  teeth  on  its 
inner  surface  ;  gills  pouch-like  ;  no  fins. 

6.    Leptocardians. 

AMPHIOXUS  (or  Branchiostoma)  :  embryonic  forms  having  a  simple  fibrous  notochord 
in  place  of  a  vertebral  column  ;  cranium  and  distinct  brain  lacking ;  heart  tubular ;  gill 
a  saccular  dilation  of  the  oesophagus  ;  no  jaws  ;  the  organs  of  the  senses  partly  wanting. 
The  species  are  all  small. 

Relation  of  Vertebrates  to  Invertebrates.—  The  Invertebrates  are  widely  separated  in 
character  from  the  Vertebrates.  The  nearest  group  to  Fishes  among  them  is  that  of  the 
Ascidians  or  Tunicates,  formerly  referred  to  the  class  of  Mollusks  and  regarded  as  not 
higher  among  species  than  the  Oyster,  all  special  organs  of  locomotion  being  absent, 
and  little  to  be  seen  in  an  outside  view  but  a  bag  with  two  holes  for  the  passage  of  water 
—  inward  at  one  hole  and  outward  at  the  other.  But  the  animals  are  little  like  Mol- 
lusks structurally,  and  have  certain  peculiarities  in  their  embryonic  development  which 
manifest  a  relationship  to  the  Vertebrates.  In  the  young  stage  some  of  them  have  a 
resemblance  in  form  and  somewhat  in  organs  to  the  tadpole  of  a  Frog  and  the  embryo-like 
fish,  Amphioxus.  The  Ascidians  are  consequently  regarded  as  related  either  to  a  prototype 
form  of  Vertebrate,  or  else  to  a  degenerate  form  in  the  Vertebrate  series.  The  relation  is 
briefly  presented  in  a  well -illustrated  article  by  Lankester  entitled  Vertebrata,  contained 
in  the  24th  volume  of  the  Encyclopaedia  Britannica. 

INVERTEBRATES. 

The  old  subdivisions  of  the  Invertebrates  are:  PROTOZOANS;  RADIATES,  including 
Polyps,  Hydrozoans,  and  Echinoderms ;  MOLLUSKS,  including  Mollusks,  Bryozoans,  and 
Brachiopods;  ARTICULATES,  including  Worms,  Crustaceans,  and  the  terrestrial  kinds, 
Myriapods,  Arachnids,  and  Insects.  Through  embryological  study  it  has  been  proved 
that  true  Protozoans  are  one-celled  in  all  stages,  the  embryo  cell  undergoing  no  subdivis- 
ion (that  is,  segmentation)  in  the  development.  In  Sponges,  on  the  contrary,  while  there 
is  much  external  resemblance  to  Protozoans,  the  germ-cell  undergoes  segmentation  as  in 
higher  species,  and  hence  there  is  a  nearer  relation  to  Polyps  than  to  the  simple  Protozoans. 
It  has  also  been  found  that  Brachiopods  are  about  as  nearly  related  to  Worms  as  to  Mol- 
lusks ;  that  Echinoderms  are  more  nearly  related  to  Worms  than  to  Polyps  and  Hydro- 
zoans, notwithstanding  the  radiate  arrangement  of  the  external  parts ;  that  Polyps  and 
Hydrozoans  (Medusae)  are  closely  related,  and  as  they  have  the  common  character  of 
a  single  opening  to  the  interior  cavity,  they  now  are  called  Ccelenterates,  from  KOI\OS,  hol- 
low, and  fvrepov,  intestine. 


BRIEF   KEVIEW   OF   THE   SYSTEM   OF  LIFE.  419 

The  Articulates  having  jointed  limbs,  including  the  terrestrial  species  and  Crustaceans, 
are  now  generally  removed  from  the  Worms,  and  placed  in  a  separate  grand  division, 
called  Arthropods  (from  the  Greek  &p0poi>,  joint,  and  a-oris,  foot).  But  the  typical  Worms 
and  the  Arthropods  are  alike  in  consisting  of  a  series  of  segments,  each  normally  having 
its  nervous  ganglion ;  and  in  this  fundamental  feature,  which  is  more  important  than  their 
differences,  both  sections  are  far  removed  from  Mollusks  and  Brachiopods,  which  are  non- 
articulates,  the  body  and  its  appendages  having  no  joints.  On  this  account  the  old  division 
of  Articulates  still  has  importance.  The  relations  of  Insects  are  even  closer,  structurally 
and  embryologically,  to  Worms,  than  to  Crustaceans,  notwithstanding  their  jointed  limbs. 
This  relation  of  Insects  to  Worms  is  shown  by  the  resemblance  of  the  larves  to  Worms  ; 
while  Crustaceans,  by  the  same  evidence,  are  proved  to  be  most  nearly  related  to  the 
precursors  of  Worms. 

The  grander  divisions  of  Invertebrates  are  as  follows :  — 


ARTICULATES. 


1.    ARTHROPODS. 

a.  The  terrestrial  or  Tracheate  species : 
1.  Insects  ;  2.  Myriapods;  3.  Arachnids. 


b.   The  aquatic  or  Branchiate  species  : 

4.  Limuloids ;  5.  Crustaceans. 
,    WORMS. 

NON-ARTICULATES.    3.   MOLLUSKS;    4.  MOLLUSCOIDS    (including  Brachiopods   an* 

Bryozoans).    The  non-segmented  Worms  might  here  make 
another  subdivision. 

{5.     ECHINODERMS. 
6.   CCELENTERATES,    including    Hydrozoans    (or    Medusae    and 
Hydroids),  and  Actinozoans  (or  Polyps). 

7.  SPOXGIOZOANS,  or  the  animals  of  the  Sponges. 

8.  PROTOZOANS,  Amceboids,  Rhizopods,  Radiolarians,  Monads, 

and  other  Flagellates,  etc. 

1.  Arthropods. 

The  TRACHEATES  have  spiracles  (breathing-holes),  a  vascular  system  for  inside  air- 
circulation,  and  one  pair  of  antennae,  or  none  ;  they  include  Insects,  Myriapods,  Arachnids. 

The  BRANCHIATES  have  gills  for  the  aeration  of  the  circulating  fluid,  or  perform  this 
function  through  the  general  surfaces  of  the  body  or  its  foliaceous  appendages.  The  spe- 
cies are  Crustaceans,  Limuloids,  and  Pycnogonids. 

1.    Insects. 

Having  the  body  in  three  parts,  that  is,  a  distinct  head,  thorax,  and  abdomen ;  and 
only  three  pairs  of  legs :  as  Hymenopters  (Ants,  Bees,  Wasps)  ;  Lepidopters  (Butterflies, 
Moths)  ;  Coleopters  (Beetles)  ;  Dipters  (Flies)  ;  Neuropters  (Dragon-flies,  May-flies) ; 
Orthopters  (Grasshoppers,  Locusts,  Cockroaches)  ;  Hemipters  (Cicada,  Squash-bug, 
Aphis);  Thysanura  (Podura,  Lepisma). 

2.  Myriapods. 

Having  a  worm-like  form,  regularly  articulate  body,  and  numerous  pairs  of  legs; 
part  have  the  body  flattened,  and  one  pair  of  legs  to  a  segment  or  somite,  the  Chilopoda, 
which  include  the  Scolopendra  and  other  Centipeds ;  and  others  have  the  body  nearly 
cylindrical,  and  two  pairs  of  legs  to  a  segment,  the  Diploopoda,  which  include  the  lulids 
and  other  Millepeds. 


420 


HISTORICAL   GEOLOGY. 


3.  Arachnids. 

Having  the  body  in  two  parts,  cephalothorax  and  abdomen  (but  in  the  lowest, 
Mites,  only  one,  —  the  abdomen  and  thorax  not  separate  segments)  :  as  Spiders,  Scorpions, 
Mites,  Ticks. 

4.  Limuloids. 

Limuloids  are  a  nearly  extinct  tribe  of  species,  related  more  nearly  to  the  Arachnids 
than  to  Crustaceans.  The  only  species  in  American  waters  is  the  Limulus  polyphemus, 
or  Horse-shoe,  common  on  the  coast  of  southern  New  England  and  to  the  southward. 
Limuloids  differ  from  Crustaceans  in  not  passing  through  the  Nauplius  stage  in  embryo- 
logical  development ;  in  having  no  antennae  corresponding  to  the  first  pair  in  Crustaceans  ; 
and  in  having  the  two  antennae  of  the  second  pair  chelate  ;  that  is,  terminating  in  pincers, 
and  used  for  conveying  food  to  the  mouth, —  a  degenerate  service  for  sense-organs. 

A  Paleozoic  group,  under  the  tribe  of  Limuloids,  includes  the  Eurypterids  —  aquatic 
species  having  the  long,  jointed  body  of  a  Caligus  among  Crustaceans,  but  occasionally 
several  feet  in  length.  For  figures,  see  pages  556,  623.  They  have  two  antennae,  like  the 
Limulus,  or  none,  and,  moreover,  the  basal  joints  of  part  or  all  of  the  legs  are  the  ani- 
mal's jaws.  Although  aquatic  species,  they  are  related  to  the  Scorpions,  a  division  of 
Spiders.  See  further,  page  513. 

5.    Crustaceans. 

The  class  of  Crustaceans  is  divided  into :  — 

(1)  Decapods  (so-named  from  the  Greek  for  ten-footed},  as  the  Crabs,   Lobsters, 
Shrimps,  usually  having  5  pairs  of  feet. 

(2)  Tetradecapods  (named  from  the  Greek  for  fourteen-footed),  as  the  Sow-bugs  and 
Sand-fleas. 

(3)  Entomostracans,  irregular  in  number  of  feet,  and  usually  without  a  regular  series 
of  abdominal  appendages. 

376-385. 


ARTICULATES.  —  (1)  Worms:  376,  Arenicola  marina,  or  Lob-worm  (x£).  (2)  Crustaceans:  377,  Crab, 
species  of  Cancer;  378,  an  Isopod,  species  of  Porcellio;  379,  an  Amphipod,  species  of  Orchestia;  380, 
an  Isopod,  species  of  Scrolls  (x  £) ;  381,  382,  Sapphirina  Iris;  381,  female;  382,  male  (x  6);  383,  Trilobite, 
Calymene  Blumenbachii ;  384,  Cythere  Americana,  of  the  Cypris  family  (x!2);  385,  Anatifa,  of  the 
Cirriped  tribe. 

In  an  early  stage  of  development,  many  young  Crustaceans  have  a  6-footed  free- 
swimming  form,  called  a  Nauplius,  2  of  the  feet  being  functionally  antennas  and  4  of 
them  legs,  the  third  pair  afterward  becoming  jaws.  All  Entomostraca  pass  through  this 
Nauplius  stage,  and  also  a  few  of  the  higher  kinds. 

Among  the  Decapods,  Crabs  are  called  Brachyurans, — from  the  Greek  for  short- 
tailed,  the  abdomen  being  small  and  folded  up  under  the  body  ;  the  Lobsters  and  Shrimps, 


BRIEF  REVIEW  OF   THE  SYSTEM  OF  LIFE.  421 

Macrurans,  —  from  the  Greek  for  long-tailed,  the  abdomen  being  rarely  shorter  than 
the  rest  of  the  body. 

Among  the  Tetradecapods,  Figs.  378,  380  represent  species  of  the  tribe  of  Isopods  (a 
word  meaning  equal-footed),  and  Fig.  379  of  that  of  Amphipods  (feet  of  2  kinds).  Fig. 
378  is  the  Sow-bug,  common  under  stones  and  dead  logs  in  moist  places.  Fig.  379  is  the 
Sand-flea,  abundant  among  the  seaweed  thrown  up  on  a  coast. 

Under  Entomostracans,  the  Cyclops  group  (Copepods)  includes  very  small  species 
having  a  shrimp-like,  or  Caridoid,  form,  as  in  Fig.  381.  Sometimes  the  male  and  female 
differ  much  in  form  :  382  is  male,  and  381  female  of  Sapphirina  Iris  ;  ab  is  the  cephalotho- 
rax,  and  bd  the  abdomen.  In  the  Cypris  group,  the  animal  is  contained  in  a  bivalve  shell, 
as  in  Fig.  384,  and  they  are  hence  called  Ostracoids. 

In  the  Phyllopod  group,  the  form  is  either  Caridoid,  approaching  Cyclops,  or  like 
Daphnia  or  Cypris;  but  the  abdominal  appendages  or  legs  are  usually  foliaceous  and 
excessively  numerous  :  the  name  is  from  the  Greek  for  leaf-like  feet.  The  Ostracoid  Phyl- 
lopods  are  multiplicate  species  (that  is,  excessive  in  number  of  body  segments  or  limbs)  of 
the  tribe  of  Ostracoids,  and  the  Caridoid  kinds  often  resemble  multiplicate  species  of 
Copepods. 

In  the  Cirriped  or  Barnacle  group,  the  animal  has  usually  a  hard,  calcareous  shell,  and 
is  permanently  attached  to  some  support,  as  in  the  Anatifa  (Fig.  385)  and  Barnacle.  The 
animal  opens  a  valve  at  the  top  of  the  shell,  and  throws  out  its  several  pairs  of  jointed 
feet  looking  a  little  like  a  curl,  and  thus  takes  its  food,  —  whence  the  name,  from  the 
Latin  cirrus,  a  curl,  and  pes,  foot.  The  Anatifa  has  a  fleshy  stem,  while  the  ordinary 
Barnacle  is  fixed  firmly  by  the  shell  to  its  support.  Barnacles  are  common  on  the  rocks  of 
the  seacoast  between  high  and  low  tide.  The  young  Cirriped  or  Barnacle  is  a  free-swim- 
ming Ostracoid,  much  like  Fig.  384  in  form,  but,  on  passing  to  the  adult  stage,  it  drops  its 
bivalve  shell,  and  commences  the  sedentary  life  of  the  species,  and  the  hard,  permanent, 
calcareous  shell  of  the  animal  is  then  formed.  As  with  other  Crustaceans  the  animal 
periodically  casts  its  skin  with  progress  in  size,  but  not  the  hard  calcareous  shell  about 
the  body.  The  shell  of  ordinary  Crustaceans  is  not  calcareous,  but  chitinous,  and  more  or 
less  flexible ;  the  Cirripeds  are  an  exception  as  regards  this  outer  shell,  but  not  in  the 
integument  over  the  legs  and  body  within  this  shell.  The  composition  of  the  chitinous 
covering  of  a  lobster  is  given  on  page  73. 

Trilobites  are  Paleozoic  Crustaceans  related  to  the  Isopods.     They  have  the  general 
form  of  an  Isopod,  the  higher  division  of  the  Tetradecapods,  and  were  placed  near  this 
group,  with  a  query,  by  the  author  in  1852.     But  they  are 
Phyllopod-like  or  multiplicate  species,  with  the  exception  of  a 
few  of  embryonic  relations.     Like  the  Isopods,  and  unlike  spe- 
cies of  Apus,  and  most  other  Entomostracans,  they  undergo  no 
metamorphosis.     Trilobites  are  represented  in  Figs.  383,  386, 
and  387-391. 

In  the  Trilobite,  the  shell  of  the  head-portion  (ab,  Fig.  383) 
is  called  the  buckler;  the  tail  (or  properly,  abdominal)  shield, 
when  there  is  one  (Fig.  383,  d),  the  pygidium.  The  buckler 
(a&)  is  divided  by  a  longitudinal  depression  into  the  cheeks  or 
lateral  areas,  and  the  glabella  or  middle  area  (Figs.  383,  386) . 

The  cheeks  are  usually  divided  by  a  suture  extending  from       Dalmaniteg  HaU8manni. 
the  front  margin  by  the  inner  side  of  the  eye  to  either  the 

posterior  or  the  lateral  margin  of  the  shell.  In  Fig.  383  (Calymene  BlumenbacMi) ,  this 
suture  terminates  near  the  posterior  outer  angle.  The  glabella  may  have  a  plane  sur- 
face, or  be  more  or  less  deeply  transversely  furrowed  (Fig.  383),  and  usually  has  only  three 
pairs  of  furrows.  The  suture  running  from  the  anterior  side  of  the  eye  forward  or  out- 
ward, and  from  the  posterior  side  of  the  eye  outward  (s  in  Fig.  386),  is  the  facial  suture; 
a  prominent  piece  on  the  under  surface  of  the  head,  covering  the  mouth,  is  called  the 


422 


HISTORICAL   GEOLOGY. 


hypostome.  The  eyes  may  be  very  large,  as  in  Dalmanites  (Fig.  386),  Phacops,  and  Asa- 
phus  (Fig.  689),  or  small,  as  in  Homalonotus  ;  or  not  at  all  projecting,  as  in  Trinucleus 
(Fig.  692) ;  and  may  also  differ  in  position  in  different  genera. 


387 


387-391. 


TRIARTHRUS  BECKII.  — Figs.  387,  388,  specimens  with  antennae  and  portions  of  cephalic  and  thoracic  ap- 
pendages (x  2)  ;  389,  portion  of  antennae  (xlO);  390,  posterior  half,  with  remains  of  feet  (x2);  391  a, 
one  of  ttie  jointed  appendages  (x  6) ;  391,  one  of  the  feet.  Matthew. 


Specimens  of  Trilobites  are  almost  always  without  appendages  of  any  kind.  Evi- 
dence of  pairs  of  slender  limbs  extending  the  whole  length  of  the  body  were  first  observed 
in  a  specimen  of  Asaphus  platycephalus,  by  Billings,  in  1870 ;  and  later,  in  1883,  in 
another  American  species,  A.  megistos,  by  Mickleborough.  New  proof  was  announced 
by  Walcott,  in  1876,  1877,  and  1881,  from  slicings  of  some  hundreds  of  specimens  of 
a  species  of  each  of  the  genera  Calymene  and  Ceraurus;  who  reached  the  conclusion 
that  there  were  four  pairs  of  slender  appendages  to  the  head-portion,  and  a  series  along 
the  whole  under  surface  to  the  extremity  of  the  pygidium  or  abdomen.  He  also  obtained 
evidence  that  the  thoracic  legs  had  at  bases  a  branch  (epipodite),  and  that  they  carried 
also  an  appendage  in  the  form  of  slender  filaments,  some  of  which  were  spiral,  which  he 
described  as  probably  branchial.  Mr.  Walcott  also  gives  figures  of  what  he  regards  as 
the  fossil  ova  of  the  Trilobites. 

These  results  have  been  in  the  main  confirmed  and  made  more  definite  from  specimens 
of  Triarthrus  Beckii,  found  by  W.  S.  Valiant,  and  described,  in  1893,  by  W.  D.  Matthew, 
some  of  which  are  represented  in  Figs.  387-391,  from  Matthew's  paper.  In  addition  to  the 
existence  of  legs,  the  specimens  figured  show  that  Trilobites  had  slender  antennae  of  the 
first  pair  (Figs.  387,  388),  consisting  of  short  joints  (Fig.  389);  and  that  the  slender, 
bifid,  jointed  feet  were,  in  part  at  least,  natatory  organs,  probably,  by  plumose  setse  (as  is 
indicated  in  Fig.  388  and  others).  The  presence  of  a  second  pair  of  antennae  is  probable, 
but  none  is  indicated.  The  specimens  were  from  a  thin  layer  in  the  Utica  shale  near 
Rome,  Oneida  County,  New  York. 

Later  investigations  of  specimens  from  the  same  locality,  by  C.  E.  Beecher  (1893, 1894) 
have  ascertained  that  the  abdominal  appendages  are  branchial,  as  in  modern  Isopods ; 
he  has  also  made  out  the  precise  form  and  other  characters  of  the  thoracic  limbs,  show- 
ing that  each  consisted  of  a  seven-jointed  leg,  and  a  long  natatory  appendage.  (See  page 
512  for  figures.) 

The  following  table  exhibits  the  homologies,  as  regards  segments  and  their  appendages, 
of  different  types  of  Crustaceans.  0  indicates  the  absence  of  a  segment,  and  the  Koman 
numerals  above,  the  normal  number  of  the  segments  in  the  cephalothorax  and  abdomen. 


BRIEF    REVIEW    OF   THE   SYSTEM   OF   LIFE. 


423 


CEPHALOTHORAX. 

ABDOMEN. 

I 

,  •  
1.  DECAPODS      Pedunc. 
(Crab).           eyes. 

2.  TETRADECA-        0 

PODS. 

II  III 

2  pairs 
of 
antennae. 

2  pairs 
of 
antennae. 

iv  v  vi  vn  vm  ix  x  xixn  xmxry 

inmivvvi 

6  pairs  of  mouth           5  pairs  of  feet, 
organs. 

6  pairs  of 
abdominal 
appendages. 

4  pairs  of                 7  pairs  of  feet, 
mouth 
organs. 

6  pairs  of 
abdominal 
appendages. 

3.  CYCLOPS.             0 

2  pairs 
of 
antennae. 

3  pairs   one     4  pairs  of        000 
of       pair     natatory 
mouth   feet.        feet, 
organs. 

usually  no 
appendages 
except  to  last 
segment. 

2.   Worms  (Vermes). 

Worm-like  in  form,  consisting  of  many  segments  not  always  distinct,  without  jointed 
legs,  though  often  furnished  with  tubercles,  lamellae,  or  bristles.  Examples :  the  Earth- 
worm, marine  Annelids,  Leeches.  Among  the  Annelids  or  higher  Worms,  the  Arenicola, 
or  Sand-worm  family,  includes  species  that  burrow  in  the  sands  of  seashores  ;  Fig.  376 
represents  the  A.  marina,  or  Lob-worm,  which  is  common  on  European  and  American 
shores,  and  grows  to  the  size  of  the  finger.  One  species  of  Eunice  has  a  length  of  4  feet. 
They  are  supposed  to  be  related  to  the  Scolithus  of  the  Cambrian  (Potsdam  Sandstone). 

Species  of  Tubicolce,  of  the  Serpula  tribe,  live  in  a  calcareous  or  membranous  tube, 
and  have  a  delicate  branchial  flower,  often  of  great  beauty,  near  the  heads.  The  tubes 
often  penetrate  corals,  and  the  branchial  flower  comes  out  as  a  rival  of  the  coral  polyps 
around  it. 

The  Rotifers  are  generally  made  a  subdivision  of  the  Worms.  They  are  minute  species, 
having  3  to  6  body  segments  ;  1  or  2  simple  eyes ;  a  pair  of  jaws  ;  disks,  situated  anteriorly, 
which  are  edged  with  movable  cilia  in  place  of  limbs.  Many  have,  in  appearance,  the 
cephalothorax  and  jointed  abdomen  of  an  Entomostracan,  and  in  this  and  other  ways 
show  a  relation  to  Crustaceans.  They  are  supposed  by  Lankester  to  have  comprised  the 
precursor  species  of  Annelids,  Crustaceans,  Limuloids,  and  other  Arthropods  ;  and  others 
compare  the  forms  of  some  with  the  embryos  of  Mollusks,  Molluscoids,  and  Holothurians, 
—  relations  that  would  make  the  group  the  Embryonoid  division  of  the  higher  Inverte- 
brates. For  figures  of  Rotifers  and  references  see  article  ROTIFERS  in  the  Encycl.  Brit. 

The  Helminths,  or  Intestinal  Worms,  need  no  especial  remarks  in  this  place,  as  they 
have  no  geological  importance. 

3.   Mollusks. 

Mollusks  consist  essentially  of  a  soft,  fleshy  bag  containing  the  stomach  and  viscera, 
without  joints  or  jointed  appendages.  They  were  named  Mollusks  from  the  Latin  mollis, 
soft.  They  have  on  either  side  a  thin  fold  of  the  skin  of  the  back,  called  the  mantle  or 
pallium  (from  the  Latin  for  cloak),  which  serves  to  inclose  a  cavity  between  it  and  the 
body,  where  are  the  gills  (branchiae)  or  aerating  organs.  The  mantle  varies  from  very 
large  to  nearly  obsolete  ;  and  in  some  (the  Pulmonates  or  land-snails)  it  is  a  covering  for 
an  internal  lung-like  organ  of  respiration.  The  ventral  surface  anteriorly  has  sometimes 
a  firm,  fleshy  projection  which  serves  as  a  foot  for  locomotion,  as  in  the  Clam,  or  for  their 
attachment  by  horny  fibers,  as  in  the  Mussel.  Again,  it  is  sometimes  spread  out  flat, 
making  a  large,  flat  foot  or  ventral  surface  for  locomotion,  as  in  the  Gastropods  ;  or  it  has 
the  anterior  part  divided  into  a  pair  of  wing-like  paddles,  as  in  the  Pteropods ;  or  into  4 


424 


HISTORICAL  GEOLOGY. 


or  6  pairs  of  arms  furnished  with  tentacles,  suction-disks,  or  horny  claws,  as  in  the  Ceph- 
alopods. 

The  subdivisions  are  as  follows :  — 

1.  Cephalopods.  Free-swimming;  having  4  or  5  or  more  pairs  of  arms  arranged 
about  the  mouth  (Fig.  392),  so  named  from  Ke$a\-i},  head,  and  irovs,  foot.  Some,  like  the 
Nautilus,  have  an  external  chambered  shell,  and  others  (Squids)  only  an  internal  bone  or 
pen.  Rhyncholites,  sometimes  found  as  fossils,  are  the  hawkbill-like  jaws  of  the  species 
of  Ammonites. 

The  subdivisions  are:  the  Tetrabranchs,  or  4-gilled  species  (Fig.  401),  including  the 

Nautili  and  Ammonites,  and  the 
Dibranchs,  or  2-gilled  species, 
which  never  have  an  external 
chambered  shell,  and  include  the 
large  Devil-fishes  and  the  Argo- 
naut, or  Octopods ;  the  Cuttle- 
fishes and  Squids,  or  Decapods 
(Fig.  392).  In  the  latter  group, 
one  pair  of  arms  is  very  long, 
and  there  is  an  internal  horny 


392. 


The  Calamary  or  Squid,  Loligo  vulgaris  (length  of  body,  6  to  12 
inches) ;  t  the  duct  by  which  the  ink  is  thrown  out;  p  the  "  pen." 


or  calcareous  bone  (shell)  some- 
times called  the  pen  (Fig.  392,  p) 
situated  in  the  back.    One  spe- 
cies of  the  Newfoundland  seas  has  the  body  15  feet  long  and  the  long  arms  about  35  feet. 
The  Sepia,  from  its  ink-bag,  affords  the  brown  paint  called  sepia;  and  its  "pen"  is  the 
spongy  cuttle-fish  bone  used  to  supply  lime  in  bird-cages. 

2.  Pteropods.  —  Free-swimming  species,  having  for  the  purpose  of  locomotion  (Fig. 
400),  a  pair  of  paddle-like  plates  near  the  head  ;  shell,  when  present,  often  slender,  conical, 
thin,  and  glassy,  but  also  of  other  shapes,  and  rarely  spiral  (Limacina).    Named  from 
irrep6f,  wing,  and  TTOVS. 

3.  Scaphopods.  — The  foot  adapted  for  burrowing.     Shell  tubular,  conical,  or  oblong, 
slender,  as  in  Dentalium.     Named  from  o-wa^os,  digging,  and  irovs. 

4.  Gastropods   (Cephalophora).  —  Head  prominent  and  furnished  with    eyes    and 
usually  tentacles  (Fig.  399) ;  the  mouth  with  a  rasp-like  tongue ;  the  foot,  for  locomotion,  a 
broad,  flat,  ventral  surface,  whence  the  name  of  the  group  (from  yacrr^p,  the  venter) ;  shell, 
a  dorsal  secretion,  usually  spiral,  but  in  Chiton,  a  jointed  symmetrical  shield  ;  in  some, 
conical ;  sometimes  wanting.     Includes  the  Snails  (Fig.  399)  among  land  species,  and  the 
spiral  shells  of  fresh  and  salt  water,  often  called  Univalves ;  also  species  without  shells, 
some  of  which  (Nudibranchs)  have  the  gills  in  flower-like  groupings  on  the  back.    The 
mantle  varies  much  in  extent,  reaching  (at  the  will  of  the  animal)  as  far  up  the  outside 
of  a  shell  as  the  surface  is  highly  polished.    Besides  the  eyes  of  the  head,  several  species  of 
Naked  Mollusks  of  the  genus  Onchidium  have  eyes  over  the  back  ;  and  these  eyes,  unlike 
those  of  other  Invertebrates,  are  like  the  eyes  of  Vertebrates  in  structure,  a  layer  of  rods 
and  cones  forming  the  outer  layer  of  the  retina,  and  the  general  arrangement  of  the  parts 
being  Vertebrate-like  (Semper,  Animal  Life,  1881,  page  371). 

5.  Lamellibranchs  (Figs.  396-398).  —  Include  the  Clam,  Oyster,  and  other  "  bivalves." 
They  have  no  eye  in  the  head  portion,  and  no  projecting  head  (whence  called  Acephals}, 
and  no  teeth  or  denticles  in  the  mouth.     The  foot  in  many  is  a  tough,  keel-shaped,  or 
flattened  muscular  projection ;  but  sometimes  it  is  small  and  spins  horny  fibers  (byssus) 
for  attachment  to  rocks,  and  sometimes  (as  in  Oysters,  etc.)  it  is  wanting.     They  have  a 
bivalve  shell,  the  valves  situated  either  side  of  the  body,  and  articulated  together  above 
between  the  umbones.     The  valves  show,  inside,  the  impressions  of  one  (at  2,  Fig.  398)  or 


BKIEF   KEVIEW   OF   THE   SYSTEM   OF   LIFE. 


425 


two  (1,  2,  Figs.  396,  397),  rarely  more,  adductor  muscles,  and  also  an  impression  of  the 
mantle  or  pallium,  which  is  concentric  with  the  lower  and  hinder  margin  of  the  shell 
in  integripallial  species,  and  has  a  sinus  posteriorly  in  sinupallial  species.  The  mantle 
is  large,  concealing  the  body,  with  the  two  sides  either  free  at  the  lower  edge,  or  not  con- 

393-401. 


MOLLUSKS,  Figs.  393-401.  —  (1)  Brachiopods :  393,  Terebratula  impressa,  of  the  Ob'lyte;  394,  Lingula  on 
its  stem.  (2)  Jiryozoans :  395  (x  8),  395  a,  genus  Eschara.  (3)  Lamellibranchs :  396,  397,  398,  the 
Oyster.  (4)  Gastropods:  399,  Helix.  (5)  Pteropods :  400,  genus  Cleodora.  (6)  Cephalopoda:  401, 
Nautilus  (xj). 

nected  (as  in  the  Oyster,  etc.),  or  else  grown  together  into  a  sac  (Venus,  Mya}-,  and  in 
the  latter  case  usually  having  the  sac  terminate  behind  in  two  tubes,  as  in  My  a,  Solen, 
one  incurrent,  for  receiving  water,  to  the  gills,  and  food,  and  the  other  excurrent.  Imper- 
fect eyes  or  eye-spots  exist  in  the  mantle  of  some  species.  Gills  are  usually  lamellar 
organs  (whence  the  name,  Lamellibranchs)  situated  between  the  mantle  and  the  body. 
In  a  few  boring  species,  the  shell  includes,  or  is  followed  by,  a  long,  calcareous  tube, 
which  may  be  1  to  2  feet  long  in  Teredo,  the  timber-borer. 


4.   Molluscoids. 

1.  Brachiopods.  —  Brachiopods  (Figs.  393,  394,  and  402-430)  have  a  bivalve  shell, 
and  in  this  respect  are  like  the  Lamellibranchs  or  ordinary  bivalves.  But  the  shell, 
instead  of  covering  the  right  and  left  sides,  covers  the  dorsal  and  ventral  sides.  More- 
over, it  is  symmetrical  inform,  and  equal,  either  side  of  a  vertical  line  ab,  Fig.  407.  The 
valves,  moreover,  are  almost  always  unequal ;  the  larger  is  the  ventral,  and  the  other  the 
dorsal.  There  is  often  an  aperture  at  the  beak  (near  6,  Fig.  393),  that  in  the  young  state 
and  often  through  the  adult  gives  exit  to  the  pedicel,  by  means  of  which  the  animal 
is  fixed  to  some  support.  Species  having  the  two  valves  hinged  together  are  called  Articu- 
late Brachiopods,  and  those  that  are  hingeless  are  the  Inarticulate.  Some  of  the  genera 
of  the  former  group  are  Orthis,  Orthisina,  Spirifer,  Ehynchonella,  Strophomena,  Penta- 
merus,  Terebratula;  and  some  of  those  of  the  latter  are  Lingula,  Lingulella,  Obolus, 
Obolella,  Discina,  Crania. 

Brachiopods  have  a  pallium,  but  no  independent  branchial  leaflets ;  and  a  pair  of 
coiled  fringed  arms,  which  in  some  cases  may  be  extruded,  —  whence  the  name  Brachio- 
pod,  meaning  arm-like  foot.  For  the  support  of  these  arms,  there  are  often  bony 
processes  (Figs.  402,  406,  and  409).  These  calcified  arm-supports,  when  present,  are  2 
thin  lamellae,  attached  to  the  interior  of  the  dorsal  valve  ;  they  are  short  and  curved  in  the 


426 


HISTORICAL   GEOLOGY. 


Rhynchonellse  (Fig.  411);  are  extended  toward  the  front  of  the  shell,  and  bent  back  and 
united,  forming  a  loop,  in  Terebratula,  Magellania,  etc.  (Figs.  403,  404,  and  402);  or  are 
extended  forward  and  coiled  in  variously  shaped  spiral  coils,  as  in  Spirifer,  Atrypa, 
etc.  (Figs.  405,  408).  In  many  extinct  genera  (Orthis,  Strophomena,  etc.)  there  are  no 
calcified  arm-supports.  These  arms  are  covered  with  vibrating  cilia,  which  serve  to  keep 
up  a  current  of  water  over  or  through  the  branchial  cavity  of  the  animal. 
A  few  of  the  species  are  represented  in  Figs.  402-430  :  — 


402-421. 


BBACHIOPODS.  —  Fig.  402,  Magellania  flavescens ;  403,  loop  of  Terebratula  vitrea ;  404,  id.  Terebratulina  caput- 
serpentis;  405,  Spirifer  striatus;  406,  same,  interior  of  dorsal  valve;  407,  Athyris  concentrica;  408,  409, 
Atrypa  reticularis,  the  latter  dorsal  valve;  410,  Rhynchonella  psittacea,  showing  the  spiral  arras  of  the 
animal;  411,  id.  dorsal  valve;  412,  id.  ventral;  413,  Strophomena  planumbona;  414,  id.  dorsal  valve;  415, 
id.  ventral;  416,  Plectambonites  transversalis;  417,  id.  dorsal  valve;  418,  id.  ventral;  419,  Orthis  stria- 
tula;  420,  id.  dorsal  valve;  421,  id.  ventral. 


BRIEF   REVIEW   OF   THE   SYSTEM   OF   LIFE. 
422-430. 


427 


Fig.  422,  Productus  aculeatus,  dorsal  view  ;  4'J3,  Producing  seiuireticulatus,  veutral  view  ;  4:i3  a,  section  of  Pro- 
ductus,  showing  Ihe  curvature  of  the  valves;  424,  Cbonetes  latus,  opposite  views;  425,  Calceola  sanda- 
lina  (a  Coral  with  lid,  resembling  a  bivalved  Brachiopod) ;  426,  Crania  antiqua;  427,  Discina  (Discinisca) 
lamellosa,  side  view;  428,  id.  showing  foramen;  429  a,  b,  Sipbonotreta  unguiculata,  opposite  views; 
430  a,  b,  Obolus  Appollinis. 

Brachiopods  are  among  the  oldest  of  fossils.  The  animals  have  been  shown  by  Morse 
to  have  close  relations  to  the  Annelids,  though  not  multiplicate  like  them,  but  when  adult 
without  distinct  segments. 

2.  Bryozoans  (Polyzoans).  —  Bryozoans,  or  Moss-animals  (so  named  with  reference 
to  the  moss-like  corals  they  often  form),  look  like  Polyps,  owing  to  the  series  of  slen- 
der ciliated  organs  surrounding  the  mouth,  as  represented  in  Figs. 
395,  395  a  ;  395  is  magnified  about  8  times ;  and  395  a  represents 
the  animal  showing  its  stomach  at  s,  and  the  flexure  in  the  ali- 
mentary canal,  with  its  termination  alongside  of  the  mouth.  The 
coral  consists  of  minute  cells  either  in  branched,  reticulated,  or 
incrusting  forms.  They  are  often  calcareous  ;  and  such  were  com- 
mon in  the  Silurian,  and  still  occur.  Eschara,  Flustra,  fietepora, 
are  names  of  some  of  the  genera.  The  Oysters  in  the  market  often 
have  their  shells  encrusted  with  large  groups  of  the  minute  cells  of 
Bryozoans. 

Fig.  431  represents  a  membranous  species  (called  Gemellaria  loricata) ;  b  is  the  moss- 
like  coral,  natural  size  ;  and  a  a  portion  of  a  branch,  enlarged,  showing  the  cells. 


431. 


BBYOZOAN,  Gemellaria 
loricata. 


5.    Echinoderms. 

Echinoderms,  while  eminently  radiate  in  the  adult  stage,  in  the  young  have  bilateral 
symmetry  ;  and  a  few  species  never  get  beyond  the  form  of  the  young.  The  exterior  is 
more  or  less  calcareous,  often  furnished  with  spines.  They  have  distinct  nervous  and 
respiratory  systems  and  also  a  complete  digestive  system.  The  name  alludes  to  the  spines 
over  the  surface  in  a  prominent  part  of  the  species,  and  is  from  echinus,  a  hedgehog. 

The  following  are  the  subdivisions :  — 

1.  Holothurioids  (Sea-slugs,  Sea-cucumbers).  —  Having  the  exterior  soft,  and  through- 
out extensile  or  contractile,  and  the  body  elongated  ;  mouth  at  one  end  surrounded  by  a 
wreath  of  branched  tentacles. 


428 


HISTORICAL   GEOLOGY. 


2.  Echinoids  (Sea-urchins) .  —  Having  a  thin  and  firm  hollow  shell,  covered  externally 
with  spines  (Fig.  441)  ;  form,  spheroidal  to  disk-shape ;  the  mouth  below,  at  or  near  the 
center,  as  the  Echinus.  Fig.  441  represents  an  Echinus  partly  uncovered  of  its  spines, 
showing  the  shell  beneath,  and  432  another,  wholly  uncovered.  The  shell  consists  of  polyg- 
onal pieces,  in  20  vertical  series,  arranged  in  10  pairs,  except  in  species  of  the  Paleozoic. 
Five  of  these  10  pairs  are  perforated  with  minute  holes,  and  are  called  the  ambulacral 
series  (a  in  Fig.  441  represents  one  pair)  ;  and  the  other  5,  alternating  with  these,  are 
called  the  inter-ambulacral  (&).  The  inter-ambulacral  areas  have  the  surface  covered 
with  tubercles,  and  the  tubercles  bear  the  spines,  all  which  are  movable  by  means  of 
muscles.  The  ambulacral  have  few  smaller  tubercles  and  spines,  or  none  ;  but  over  each 
pore  (or  rather  each  pair  of  pores)  the  animal  extends  out  a  slender  fleshy  tentacle  or 
feeler,  which  has  usually  a  sucker-like  termination  and  is  used  for  clinging  or  for  loco- 
motion. In  Fig.  432,  the  inter-ambulacral  areas  are  broad  and  the  plates  large,  but  the 
ambulacral  are  narrow  and  the  plates  indistinct.  The  wow^-opening  is  situated  below, 
at  the  center  of  radiation  of  the  plates.  The  anal  opening  in  the  Regular  Echinoids 
(Fig.  441)  is  in  the  opposite  or  dorsal  area  or  center  of  radiation.  Around  the  dorsal  area 
there  are  5  minute  genital  openings.  In  the  Irregular  Echinoids  —  constituting  a  large 
group  —  the  anal  opening  is  to  one  side  of  this  dorsal  center  of  radiation,  and  often  on  the 
ventral  or  under  surface  of  the  animal.  In  Fig.  432,  for  example,  the  anal  opening  is 
marginal  instead  of  central,  while  the  genital  pores  are  around  the  dorsal  center,  as  in 
the  Eegular  Echinoids.  To  one  side  of  the  dorsal  center  in  the  Regular  Echinoids,  there 


432-434. 


434 


ECHINODERMS.  —  Fig.  432,  an  Echinus  without  its  spines,  — the  Clypeus  Hugi  of  the  Oolyte;  433,  the  living 
Pentacrinus  caput-raedusse  of  the  West  Indies  (x  £) ;  a,b,  c,  d,  outlines  of  the  stems  of  different  species 
of  Pentacrini;  434,  plates  composing  the  body  of  the  Crinoid,  Batocrinus  longirostris. 

is  a  small  porous  prominence  on  the  shell,  often  called  the  madreporic  body,  from  a  degree 
of  resemblance  in  structure  to  coral.  In  some  of  the  Irregular  Echinoids,  this  madreporic 
body  is  in  the  center  of  dorsal  radiation. 

The  ambulacral  areas  are  sometimes  equally  perforated  throughout  their  length. 
But  in  other  cases  only  a  dorsal  portion  is  conspicuously  perforated,  as  in  Fig.  432,  and,  as 
this  portion  has  in  this  case  some  resemblance  to  the  petals  of  a  flower,  the  ambulacra  are 
then  said  to  be  petaloid.  A  large  part  of  Echinoids  have  a  circle  of  6  strong,  calcareous 
jaws  in  the  mouth  ;  in  a  portion  of  the  Irregular  Echinoids  there  are  no  jaws. 

3.  Asterioids  ( Star-fishes') .  —  Having  the  exterior  stiffened  with  articulated  calcareous 
granules  or  pieces,  but  still  flexible  ;  form  star-shaped  or  polygonal ;  the  viscera  extending 


BRIEF    REVIEW    OF   THE    SYSTEM   OF    LIFE. 


429 


into  the  arms  ;  mouth  below,  at  center ;  arms  or  rays  with  a  groove  on  the  lower  side, 
along  which  the  locomotive  suckers  protrude  through  perforated  plates  ;  eyes  at  the  tips  of 
the  arms.  Ex.,  the  Star-fish,  Fig.  442. 

4.  Ophiuroids  (Serpent- Stars').  —  Having  a  disk-like  body  with  a  star-shaped  mouth 
beneath,  and  long,  jointed,  flexible  arms,  which  sometimes  subdivide  by  forking,  but  never 
bear  pinnae,  and  have  no  grooves  along  the  under  side,  nor  eyes  at  the  slender  tips.     The 
viscera  do  not  extend  into  the  arms  ;  the  ovarial  openings  are  slit-like,  between  the  bases 
of  the  arms  ;  and  there  is  no  anal  orifice.    The  disk  part  is  homologous  with  the  whole  of 
an  Asterioid. 

5.  Crinoids  (including  Comatulids}. — Like  ordinary  star-fishes  in  having  flexible 
arms  or  rays  ;  but  the  calcareous  secretions  of  the  rays  and  body  constitute  a  series  of 
closely  fitting  solid  pieces,  and  the  viscera  are  confined  to  the  body  portion.    The  rays  are 

435-444. 


44d 


RADIATES.—  Figs.  435-444.  1.  Polyps  :  Fig.  435,  an  Actinia;  436,  a  Coral,  Dendrophyllia ;  437,  a  Coral  of 
the  genus  Gorgonia.  2.  Hydrozoans  :  438,  a  Medusa,  genus  Tiaropsis;  439,  Hydra  (x  8)  ;  440,  Syn- 
coryne.  3.  Echinoderms  :  441,  Echinus,  the  spines  removed  from  half  the  surface  (x  £) ;  442,  Star-fish, 
Palaeaster  Niagarensis  ;  443,  Crinoid,  Encrinus  liliiformis  ;  444,  Crinoid,  of  the  group  of  Cystoids,  Cal- 
locystites  Jewetti. 


often  very  much  subdivided,  and  bear  pinnae,  in  which  the  generative  organs  are  situated. 
The  species  are  mostly  fossil,  and  are  among  the  earliest  in  geological  history.  A  few 
kinds  still  live  in  the  ocean  mostly  below  20  fathoms,  some  at  great  depths.  There  are  3 
tribes  of  Crinoids  :  — 

1.  The  Brachiates  (Encrinites) .  — Having  a  radiate  structure,  and  arms  proceeding 
from  the  margin  of  the  disk ;  also  generally  a  stem,  consisting  of  calcareous  disks,  by 
which,  when  alive,  they  are  attached  to  the  sea-bottom  or  some  support,  so  that  they  stand 
in  the  water  and  spread  their  rays,  like  flowers,  the  mouth  being  at  the  center  of  the 
flower.  Crinoids  are  represented  in  Fig.  443,  Fig.  433,  and  Fig.  30  on  page  58.  The 
second  and  third  are  living  species  from  the  West  Indies,  found  at  depths  below  20 
fathoms.  The  rays  open  out,  when  alive,  and  then  the  animal  has  its  flower-like  aspect. 
The  little  pieces  that  make  up  the  stem,  looking  like  button-molds,  are  either  circular,  as 
in  Fig.  443  a,  or  5  sided,  as  in  Figs.  433  a,  6,  c,  d.  Under  the  Crinidea  fall  the  Comatulce 
(Antedon,  etc.),  which  are  free  when  adult,  but  have  jointed  cirri  proceeding  from  the 
back  surface  for  attachment. 


430 


HISTORICAL  GEOLOGY. 


2.  The  Blastoids  (Pentremites,  etc.).  —  Having  a  symmetrical  ovoidal  body,  with  5 
petal-like  ambulacra  meeting  at  the  summit,  without  proper  arms,  and  attached  by  a  stem 
like  that  of  the  Encrinites. 

3.  The  Cystoids  (from  the  Greek  for  a  bladder},  Fig.  444.  —  Arrangement  of  the  plates 
not  often  regularly  radiate.    Arms,  when  present,  proceeding  from  the  center  of  the  sum- 
mit instead  of  the  margin  of  a  disk  ;  in  some,  only  2  arms  ;  in  others,  replaced  by  radiat- 
ing ambulacral  channels,  which  are  sometimes  fringed  with  pinnules. 

In  ancient  Crinoids,  the  arms  are  not  generally  free  down  to  the  base,  but  there  is  a 
union  of  their  lower  part,  either  directly  or  by  means  of  intermediate  plates,  into  a  cup- 
shaped  body  or  calyx  (as  in  Fig.  443,  and  also  Figs.  995,  999,  under  the  Subcarboniferous 
period,  page  640). 

In  Fig.  434,  the  plates  of  one  of  these  cups,  in  the  species  Batocrinus  longirostris 
H.,  are  spread  out,  the  bottom  plates  of  the  cup  being  at  the  center.  The  plates,  it  is 
seen,  are  in  5  radiating  series,  corresponding  to  the  5  rays  or  arms  of  the  Crinoid,  and 
between  are  intermediate  pieces.  The  3  plates  numbered  1  are  called  the  basal,  as  the 
stem  is  articulated  to  the  piece  composed  of  them ;  3,  3,  3  are  the  radial ;  4,  4,  supra- 
radial  ;  5,  brachial,  situated  at  the  base  of  the  arms  ;  7  are  immediate  plates,  called  inter- 
radial  ;  8,  another  intermediate,  the  inter-supraradial.  Sometimes,  in  other  Crinoids, 
there  is  another  series  of  plates,  at  the  junction  of  the  plates  1  and  3,  called  sub-radial. 
Finally,  the  anal  opening  of  a  Crinoid  is  situated  toward  one  side  of  the  disk,  it  being 
lateral,  as  in  the  Echinoid  in  Fig.  432;  and  the  intermediate  group  plates  numbered  10 
are  called  the  anal. 

In  the  Cystoids,  the  aperture  is  generally  lateral  and  remote  from  the  top,  as  in  Fig. 
444,  while  the  arms  often  come  out  from  the  very  summit.  The  Cystoids  are  also  peculiar 
in  what  are  called  pectinated  rhombs  (see  Fig.  444)  ;  that  is,  rhombic  areas  crossed  by  fine 
bars  and  openings  ;  the  use  of  them  is  uncertain,  —  though  they  are  probably  connected 
with  an  aquiferous  system  and  respiration. 

6.    Coelenterates. 

The  Ccelenterates  are  distinguished  from  Echinoderms  by  the  existence  of  only  one 
opening  to  the  digestive  system,  the  mouth.  Moreover,  the  tentacles  and  other  parts  are 
never  normally  a  multiple  of  5,  but  either  of  4  or  6 ;  of  4  in  Hydrozoans  and  4  or  6 
in  Polyps. 

1.  Hydrozoans  (Acalephs,  Medusae,  Jelly-fishes,  Hydroids). — Having  the  body,  in  the 
adult  stage,  usually  nearly  transparent  or  translucent,  looking  jelly-like  ;  and  internally  a 

stomach-cavity,  with  radiating  branches.  Ex.,  the 
Medusa,  or  Jelly-fish  (Fig.  438),  which  generally 
floats  free,  when  in  the  adult  stage,  with  the  mouth 
downward.  The  Hydra  and  allied  species  are 
here  included.  Most  marine  Hydroids  at  times 
produce  sexual  buds,  which,  in  many  species,  break 
away  and  become  free  jelly-fishes. 

Many  of  the  Hydroids  make  corals,  and  hence 
are  common  as  fossils.  Fig.  439  represents  a  Hydra 
enlarged,  with  a  young  one  budded  out  from  its 
side.  Some  species  of  the  group  —  those  of  the 
Sertularia  tribe  —  form  delicate  chitinous  corals, 
such  as  are  represented  in  Fig.  445,  in  which  each 
notch  on  the  little  branchlets  corresponds  to  the 
cup-shaped  cell  from  which  an  animal  protrudes 
its  flower-shaped  head,  (a  is  the  Sertularia 
abietina;  6,  S.  rosacea;  and  a',  6',  portions  of  branches  enlarged.)  The  interior  cavities 


HYDROZOANS.     Figs,  a,  a',  Sertularia  abie- 
tina; b,  b',  8.  rosacea. 


BRIEF  REVIEW   OF  THE  SYSTEM  OF  LIFE.  431 

of  each  animal  communicate  freely  with  the  tube  in  the  stem  ;  and  in  this  they  differ  from 
Bryozoans,  whose  groups  have  no  tubular  axis.  The  ancient  Graptolites  (some  of  which 
are  represented  on  page  610)  are  supposed  to  have  been  of  this  nature.  Others  secrete 
calcareous  corals  of  large  size,  and  are  called  Millepores  (because  the  minute  cells  from 
which  the  animals  protrude  are  like  pinpunctures  in  size,  and  very  numerous  over  the 
surface  of  the  coral).  The  Millepores  are  common  in  the  West  Indies  and  other  coral  seas. 
The  minute  animals  of  a  Millepore  have  nearly  the  form  represented  in  Fig.  440,  which 
represents  a  species  of  another  genus,  called  Syncoryne. 

There  are  hence  stony  corals  made  by  Polyps,  by  Hydrozoans,  and  by  Bryozoans ;  and 
others  that  are  made  by  sea-plants,  as  explained  beyond. 

2.  Actinozoans,  Anthozoans,  or  Polyps.  —  Fleshy  animals,  like  a  flower  in  form, 
having  above  (Figs.  435,  436)  a  disk,  with  a  mouth  at  center,  and  a  margin  of  tentacles  ; 
internally,  a  radiated  arrangement  of  fleshy  muscular  plates ;  and  living  for  the  most  part 
attached  by  the  base  to  some  support.  Ex.,  the  Actinia,  or  Sea-Anemone,  and  the  ani- 
mals of  ordinary  corals. 

There  are  two  groups  of  coral-making  Polyps :  — 

1.  ACTINOIDS  (Zoantharia)  (Figs.  435,  436),  which  make  the  ordinary  corals.     The 
rays  or  tentacles  of  the  Polyps  are  naked,  that  is,  without  a  fringe  of  papillae.    In  the 
Madreporaria,  the  number  of  tentacles  is  a  multiple  of  6  ;  in  the  Cyathophylloids  or  Tetra- 
coralla,  a  multiple  of  4. 

The  coral  is  secreted  within  the  Polyps,  and  not  outside  as  in  the  case  of  shells.  It  is 
usually  covered  with  radiate  cells,  each  of  which  corresponds  to  a  separate  Polyp  in  the 
group.  The  calcareous  rays  or  septa  are  made  in  the  spaces  between  the  fleshy  partitions 
in  the  interior  of  the  Polyp.  The  material  is  calcium  carbonate  (limestone)  ;  and  it  is 
taken  by  the  Polyp  from  the  water  in  which  it  lives,  or  from  the  food  it  eats. 

2.  ALCYONOIDS  (Alcyonaria}  (Fig.  437),  or  those  of  the  Gorgoniaand  Alcyouium  corals. 
The  rays  of  the  Polyps  are  8  in  number,  and  fringed.     Fig.  437  represents  a  part  of  a  branch 
of  a  Gorgonia  (Sea-Fan),  with  one  of  the  Polyps  expanded.     The  branch  consists  of  a 
horn-like  axis  and  a  fragile  crust.    The  crust  is  partly  calcareous,  and  consists  of  the  com- 
mon tissue  (coenenchyma)  by  which  the  Polyps  are  united  together ;  the  axis  is  secreted 
by  the  inner  surface  of  the  crust.    The  precious  coral  used  in  jewelry  comes  from  the 
shores  of  Sicily  and  some  other  parts  of  the  Mediterranean,  and  belongs  to  this  Alcyonoid 
division.    It  is  related  to  the  Gorgonias,  but  the  axis  is  red  and  stony  (calcareous)  instead 
of  being  horny  ;  and  this  stony  axis  is  the  coral  so  highly  esteemed.    A  few  species  make 
calcareous  corals  much  like  those  of  the  Actinoids  without  any  separate  crust. 

7.   Spongiozoans. 

1.  The  Sponges  (Porifera)  are  mostly  complex  groups  of  animals,  having  internal 
membranes  composed  of  ciliated  cells  resembling  the  collared  Flagellate  Protozoans.  Some 
simple  sponges  are  of  one  Zooid  only.  The  groups  secrete,  excepting  in  one  tribe,  —  the 
gelatinous  Sponges,  or  Halisarcoids, — a  framework  (1)  of  horny  fibers,  or  (2)  of  horny 
fibers  set  with  siliceous  spicules  ;  or  (3)  of  siliceous  spicules  or  fibers ;  or  (4)  of  calcar- 
eous spicules  or  fibers.  Of  these  4  kinds,  the  first  are  the  Corneous  Sponges  of  com- 
merce; the  second,  the  Corneo- siliceous,  a  harsh  and  more  brittle  kind;  the  third,  the 
Siliceous  ;  the  fourth,  the  Calcareous  or  Calcispongice. 

Some  of  the  forms  of  the  spicules  of  the  corneo-siliceous  and  siliceous  sponge-spicules 
are  shown  in  Figs.  446-460,  by  Hinde.  All  these  spicules  were  found  by  Hinde  in  powder 
filling  a  single  small  cavity  in  flint  from  Norfolk,  England.  All  are  much  enlarged. 

The  Hexactmellid  Sponges  are  siliceous  and  have  the  framework  made  up  of  spicules 
with  rays  crossing  at  right  angles,  making  it  6-rayed  at  the  crossing ;  they  are  mostly 
from  great  depths  ;  Tetractinellids  are  4-rayed.  But  simple  forms  accompany  the  more 
complex.  The  Sponges  occur  at  all  depths  in  the  ocean  and  are  very  various  in  shape. 


432 


HISTORICAL   GEOLOGY. 


The  hexactinellid  sponge  Euplectella  (Vemis's  Elo  wer-Basket) ,  Fig.  29,  page  57,  which 
looks  as  if  made  of  a  network  of  spun  glass,  comes  from  a  depth  of  50  fathoms  in  the  East 
Indies.  The  fossil  Diclyophyton  and  Euphantcenia  are  related  to  Euplectella,  as  shown 
by  Whitfield.  Sponges  are  mostly  marine ;  but  a  few,  like  the  Spongillce,  grow  in  fresh 
water  and  contribute  siliceous  spicules  to  peat  and  other  swamp  deposits.  The  death  and 
decay  of  Sponges  adds  largely  to  the  silica  of  the  sea-bottom. 

446-460. 


45T          458 


SPONGB-SPICULES.—  Figs.  446-449,  Geodia  or  allied;  450,  Globostellate  spicule,  near  Geodia  ;  451,  Stel- 
letta;  452,  Carterella;  453,  454,  Tetractinellid  spicules  ;  455,  Ventriculites,  Hexactinellid;  456,  Ragadinia 
annulata ;  457,  Tisiphonia ;  458,  the  same? ;  459,  Racodiscula ;  460,  Plinthosella  squamosa.  Figs.  450,  453, 
454  (x  10);  456  (x68);  others  (x34).  Hinde. 

8.   Protozoans. 

Among  Protozoans  only  the  Khizopods  and  Radiolarians  have  prominent  importance. 

1.  Rhizopods  (Foraminifers) .  —  Species  mostly  minute,  often  forming  shells;  the 
shells,  with  few  exceptions,  not  larger  than  the  head  of  a  pin  :  but  the  groups  sometimes 
having  the  shape  of  disks  an  inch  in  diameter,  and  occasionally  of  large  massive  forms. 
They  have  usually  calcareous  shells  called  Foraminifers  (from  foramen),  and  these  have 
contributed  largely  to  the  formation  of  limestone  strata.  They  consist  of  1  or  more  cells  ; 
and  the  compound  kinds  present  various  shapes,  as  illustrated  in  Eigs.  461-474.  The 
arrangement  in  a  group  is  usually  alternate  or  spiral.  Others  make  a  shell  or  test  by  the 
agglutination  of  grains  of  sand  or  other  material. 


Figs.  461-474  — RHIZOPODS,  much  enlarged  (excepting  473,  474).  Fig.  461,  Orbulina  universa  ;  462,  Glo- 
bigerina  rubra;  463,  Textularia  globulosa  Ehr.  ;  464,  Rotalia  globulosa  ;  464  a,  Side-view  of  Rotalia 
Boucana  ;  465,  Grammostomum  phyllodes  Ehr.  ;  466,  a,  Frondicularia  annularis ;  467,  Triloculina  Jose- 
phina;  468,  Nodosaria  vulgaris;  469,  Lituola  nautiloides;  470,  a,  Flabellina  rugosa  ;  471,  Chrysalidina 
gradata ;  472,  a,  Cuneolina  pavonia  ;  473,  Nummulites  nummularius  ;  474  a,  b,  Fusulina  cylindrica.  All 
but  the  last  two  magnified  10  to  20  times. 


BRIEF   REVIEW   OF   THE   SYSTEM   OF   LIFE. 


433 


475. 


Globigerinae,  with  Diatoms,  from 
a  deposit  off  Alligator  Reef 
(x  15).  A.  Agassiz. 


Fig.  461  is  a  1-celled  species  ;  the  others  are  compound,  and  contain  a  number  of 
exceedingly  minute  cells.  A  few  are  comparatively  large  species,  and  have  the  shape  of 
a  disk  or  coin,  as  Fig.  473,  a  Nummulite,  natural  size  ;  the  figure  shows  the  interior  cells 
of  one  half  :  these  cells  form  a  coil  about  the  center.  Orbitoides  is  the  name  of  another 
genus  of  coin-like  species.  Fig.  474  a  is  a  species  of  Fusu- 
lina,  a  kind  nearly  as  large  as  a  grain  of  wheat,  related  to 
the  Nummulites ;  474  b  is  a  transverse  view  of  the  same. 
This  is  one  of  the  ancient  forms  of  Rhizopods,  occurring  in 
the  rocks  of  the  Coal  formation.  Rhizopods  of  the  genus 
Globigerina  and  other  forms  have  been  already  mentioned 
(page  144)  as  the  chief  constituents  of  the  calcareous  ooze 
or  mud  making  much  of  the  sea-bottom.  Fig.  475  repre- 
sents an  aggregation  of  Globigerinse  with  Diatoms,  found 
at  a  depth  of  880  feet,  off  Alligator  Reef,  near  the  south 
coast  of  Florida,  as  figured  by  A.  Agassiz. 

Each  Rhizopod  cell  is  occupied  by  a  separate  animal  or 
zooid,  though  organically  connected  with  the  others  of  the 
same  group  or  shell.  The  animal  is  of  the  simplest  kind, 
having  no  mouth  or  stomach,  and  no  members  except  slen- 
der processes  of  its  own  substance,  which  it  extrudes  through 
pores  in  the  shell,  if  it  have  any.  The  name  Rhizopods  comes  from  the  Greek  for  root- 
like  feet,  —  in  allusion  to  the  root-like  processes  they  throw  out.  Some  of  the  species  not 
secreting  shells  (as  in  the  genus  Amoeba}  have  been  seen  to  extemporize  a  mouth  and 
stomach.  When  a  particle  of  food  touches  the  surface,  the  part  begins  to  be  depressed, 
and  finally  the  sides  of  the  depression  close  over  the  particle,  and  thus  mouth  and  stom- 
ach are  made  when  needed ;  after  digestion  is  complete,  the  refuse  portion  is  allowed 
to  escape. 

The  shells  of  some  Rhizopods  do  not  con- 
sist of  distinct  cells :  the  aggregate  living  mass 
secretes  carbonate  of  lime,  without  retaining 
the  distinction  of  the  zooids.  This  is  the  case, 
as  Carpenter  has  observed,  in  the  Nummulite- 
like  genus  Orbitolites.  Some  species  make 
large  coral-like  masses  instead  of  small 
shells. 

2.    Radiolarians     (Polycystines).  —  Se- 
crete siliceous  shells  which  are  symmetrically 
radiate  or  circular.    Three  species,  from  the 
Barbados,   are   represented  in  Figs.  476  to 
478.     Fig.  476,  Lychnocanium  lucerna  Ehr. ;   Fig.  477,  Eucyrtidium  Mongolfieri  Ehr.  ; 
Fig.  478,  Halicalyptra  fimbriata  Ehr.,  the  first  two  magnified 
100  diameters,  the  last  about  75.    From  these  deeply  concave 
forms,  there  are  gradations  in  one  direction  to  disks  with  con- 
cave centers,  and  to  flat  disks,  both  with  plain  and  pointed 
borders,  and  in  the  other  direction  to  elongate,  conical,  and 
spindle-shaped  forms.     Others  have  the  shape  of  a  flattened* 
cross;  another  is  an  open  diamond,  with  narrow  diagonals  and 
periphery.     The  disks   have  a  concentric,  and  not  a  spiral, 
structure,  and  thus  are  unlike  those  of  Nummulites. 

The  annexed  figure  represents  a  minute  spherical  species 
of  Radiolarian  —  a  jelly-like  globule  bristled  with  spicules — 

which  sometimes  beclouds  the  water  in  the  Pacific  and  East  Indian  seas  (Sphcerozoum 
orientale  D.). 

DANA'S  MANUAL  —  28 


476. 


477. 


478. 


476,  Lychnocanium  lucerna  ( x  100)  ;  477,  Eucyr- 
tidium Mongolfieri  (x  100)  ;  478,  Halicalyptra 
fimbriata  (x  75). 


479. 


434 


HISTORICAL  GEOLOGY. 


VEGETABLE  KINGDOM. 

A  cell  with  its  contents  is  the  fundamental  element  of  a  plant,  and  the  simplest  and 
lowest  plants  are  the  microscopic  unicellular  kinds ;  that  is,  those  made  of  a  single  cell,  or 
a  few  in  a  series,  as  the  lower  ALG.E  and  lowest  FUNGI.  From  these,  the  grade  in  species 
rises  through  larger  Algae,  and  other  kinds  consisting  of  cellular  tissue,  as  the  FUNGI, 
HEPATICJE,  and  MOSSES,  to  those  which  contain  also  vascular  tissue,  but  subordinately  to 
the  cellular  —  as  the  FERNS,  EQUISETA,  LYCOPODS.  The  kinds  thus  far  mentioned  are 
Cryptogams,  or  the  Flowerless  plants. 

The  remaining  plants,  or  those  producing  true  flowers  and  seeds,  are  called  Phceno- 
gams.  They  consist  of  cellular  tissue  and  woody  fibers ;  and  also,  of  vascular  tissue  in 
the  larger  part  of  the  species. 

PH^ENOGAMS. 

Phsenogams  are  divided  into  two  sections,  on  the  basis  of  the  structure  of  the  embryo 
or  seed,  and  the  growth.  In  the  Exogens,  the  embryo  consists  of  two  or  more  parts  called 
cotyledons.  Further,  as  the  name  Exogen  implies  (it  signifying  growth  by  the  out- 
side), there  is,  after  the  first  year,  with  rare  exceptions,  an  annual  addition  of  a  layer  of 
woody  tissue  between  the  wood  and  bark.  In  a  section  of  an  exogenous  stem  more  than 
a  year  old,  the  wood  has,  consequently,  rings  of  growth. 

In  the  Endogens,  the  seeds  consist  of  a  single  cotyledon.  Besides,  there  are  no  rings 
of  growth,  and  no  separable  bark  ;  growth  goes  forward  mainly  by  the  pushing  out  of 
buds  at  the  extremity  of  the  stem  or  of  its  branches.  The  structure  of  the  wood  is  said 
to  be  endogenous. 

1.  Exogens. 

Exogenous  species  are  of  two  divisions  called  Gymnosperms  and  Angiosperms. 


480. 


Cycas  circinalis, 


1.  Gymnosperms. — In  this  inferior 
division  of  the  Exogens,  the  seeds  are 
naked  and  there  is  no  stigma.  The 
fruit  often  consists  of  a  cone  made 
of  scales  with  the  seeds  beneath 
the  scales.  They  are  called  Gymno- 
sperms (from  the  Greek  for  naked  seed) 
in  allusion  to  the  naked  or  uncovered 
state  of  the  seed.  The  inferiority  to 
other  Phaenogams  is  manifested  not 
only  in  the  simple  character  of  the 
flower,  but  also  in  the  wood,  which 
contains  no  vascular  tissue,  and  this 
inferiority  accords  with  the  fact  that 
they  preceded  geologically  other  Phse- 
nogams. The  inferior  division,  that  of 
Cycads,  is  now  few  in  species,  but  for- 
merly included  a  large  part  of  the  com- 
mon forest  trees.  The  Cycads  (with 
the  related  Zamise)  are  peculiar  in 
combining  the  structure  and  fructifi- 
cation of  the  Gymnosperm  with  the 
habit  of  a  Palm,  and  the  method  of 
uncoiling  the  leaves  as  they  are  devel- 
oped which  belongs  to  Ferns.  The 


BRIEF   REVIEW   OF  THE   SYSTEM  OF  LIFE. 


435 


483. 


481. 


482. 


wood  of  the  modern  tree  has  a  very  large  pith  abounding  in  starch,  surrounded  by  one  or 

more  rings  of  wood,  each  the  result  of  several  years'  growth. 

The  ordinary  "Evergreen"  trees,  as  the  Pine,  Spruce,  Arbor  Vitae,  Yew,  belong  to 

the  second  and  higher  subdivision,  the  Conifers,  so-called  because  the  flowers  and  fruit 

ordinarily  have  the  form  of  cones.     In  the 

Pine  family  the  fruit  is  a  cone  ;  but  not  so  hi 

the  Yews.     The  Salisburia,  or  Ginkgo,  a  tree 

with  short  and  broad,  somewhat  fanlike  leaves, 

is  generally  referred  to  the  Yew  family,  though 

having  some  relations  to  the  Cycads. 

The  woody  fiber  of  the  Conifers  is  marked 

with  circular  disks  as  in  Figs.  481,  482  ;  fossil 

woods  of  the  order  may  thus  be  distinguished, 
and  genera  may  often  be 
distinguished  by  their  ar- 
rangement. 

Another  aberrant 
group,  the  Gnetacece,  in- 
cludes the  genera,  Gnetum, 
Ephedra,  and  Wei  witschia ; 
and  the  last,  of  which  only 
one  species  exists,  and  that 
in  Africa,  approaches  the 
Angiosperms,  in  its  flower, 
"the  staminal  flower  con- 
taining a  rudimentary 
ovule."  But  it  has  the 

broad  strap-like  leaves  of  the  ancient  Cordaites,  and  also,  as  the  Fig.  483  shows,  the 

winged  form  of  fruit  characteristic  of  the  Carboniferous  Cardiocarpus. 

2.   Angiosperms.  —  The  higher  Exogens,  or  the  Angiosperms,  have  the  seeds  covered  ; 

the  flowers  perfect,  the  wood  consisting  largely  of  vascular  tissue  as  well  as  woody  fibers. 

Examples  are  the  Maple,  Elm,  Apple,  Chestnut,  Rose. 

2.   Endogens. 

The  Endogens  are  represented  by  the  Palm,  Rattan,  Smilax,  Grasses,  Orchids.  A 
section  of  a  woody  stem,  as  that  of  a  Rattan  (a  species  of  Calamus)  or  Smilax,  shows  the 
ends  of  woody  fibers  and  ducts.  The  leaves  are  parallel-veined  instead  of  net-veined, 
and  not  toothed,  and  the  parts  of  the  flower  are  commonly  in  threes. 


Circular  disks  on  the 
woody  fibers  of 
Conifers. 


Fig.  483,  Welwitschia  mirabilis,  showing  trans- 
verse section  of  fruit,  with  the  outline  of  the 
fruit  finished  in  dotted  lines. 


CRYPTOGAMS,  OR  FLOWERLESS  PLANTS. 
1.   The  Higher  Cryptogams,  or  Acrogens. 

The  Acrogens  consist  of  cellular  tissue  with  more  or  less  of  fibro-vascular  tissue,  and 
are  capable  of  upward  growth,  whence  the  name  from  fapov,  top,  and  yewaw,  grow. 

The  lowest  species  have  special  interest  in  the  geological  history  of  plants.  They  are 
called  Rhizocarps  (root-fruited)  from  the  position  of  the  fruit  at  the  base  of  the  stem,  or 
at  the  root.  The  figures  represent,  half  the  natural  size,  species  of  three  of  the  very  few 
forms  now  existing.  They  show  the  position  of  the  nuts,  and  the  unlikeness  of  the  species 
in  habit  to  most  Cryptogams.  Fig.  486,  of  Salmnia  natans,  represents  a  section  of  the 
plant  showing  only  one  of  the  pairs  of  leaves  in  the  floating  plant. 


436 


HISTORICAL  GEOLOGY. 


The  other  principal  divisions  of  the  Acrogens  are  the  following :  — 

(1)  Equiseta,  or  Horse-tails.  — The  existing  species  have  hollow- jointed,  slender  stems ; 
the  leaves  arranged  in  whorls  at  the  nodes  ;  and  the  cone-like  fructification  at  the  ends  of 
the  stems.    Ancient  species  grew  with  stout  trunks  to  a  height  of  30  feet  or  more. 

(2)  Lycopods,  or  Ground-Pines.  —  The  Lycopods  have  many  leaves,  with  the  habit  of 


484. 


485. 


RHIZOCARPS.  —  Fig.  484,  Pilularia  globulifera,  with  fructification;  485,  Marailea  quadrifolia,  with  an  enlarged 
view  of  the  nut;  486,  Salvinia  natans,  part  of  plant.    All  half  the  natural  size,    Luerssen. 


a  Spruce  or  Pine  ;  they  are  small  plants  now,  but  in  the  Coal  era  grew  up  as  trees,  30  to 
90  feet  in  height. 

(3)  Ferns.  —  Modern  Ferns  sometimes  make  trees  20  to  30  feet  high. 


2.   The  Lower  Cryptogams. 


The  Lower  Cryptogams  consist   of   cellular  tissue  alone, 
are:  — 


The  principal  groups 


1.  Mosses.  — Green,  terrestrial  plants  having  delicate  leaves  along  the  slender  stems  ; 
limited  to  a  few  inches  in  the  height  of  the  living  part  of  stems.     Closely  related  to  the 
Mosses  are  the  Hepaticce,  or  Liverworts. 

2.  Lichens. — Dry  plants,  of  gray,  brown,  and  black  colors,  making  fronds  without 
leaves,  which  spread  over  the  surfaces  of  rocks,  the  outer  bark  of  trees,  etc. 

3.  Fungi.  —  Succulent  plants,  gray  to  brown  in  color,  and  never  green  ;  without 
foliage  ;  grading  down  to  Molds,  which  consist  of  strings  and  groups  of  cellules,  and  to 
Bacteria  and  other  microscopic,  free-swimming,  unicellular  kinds. 

4.  Algae,  or  Seaweeds.  — The  water-plants  are  green  to  brown  in  color,  and  contain 
more  or  less  chlorophyl.      They  graduate  downward  from  ordinary  seaweeds  to  micro- 
scopic, free-swimming,  unicellular  kinds.     Of  like  grade  with  the  unicellular  species  are 
other  kinds  having  the  form  of  threads  or  groups  of  threads,  each  thread  consisting  of  a 
series  of  cells.    The  lowest  groups  include  the  species  of  Protococcus,  of  which  P.  nivalis 
is  red  and  gives  the  red  color  to  the  snow  or  ice  in  some  Alpine  regions.    The  Diatoms 


BRIEF   REVIEW    OF   THE   SYSTEM   OF   LIFE. 


437 


having  siliceous  shells  are  others.     A  few  species  are  represented  in  Figs.  487-493. 
Another  group  is  that  of  Desmids,  which  consist  of  one  or  a  few  greenish  cells,  and  secrete 
little  or  no  silica.     They  are  related  to  the  common  Conferva  (frog-spittle)  of  fresh-water 
pools.     Other  calcareous  kinds  take  delicate  branching  forms,  as  the  Corallines ;  or  more 
stony  forms,  like  those  of  Corals,  but  destitute  of  surface  cells,  as  the  Nullipores ;  or 
sponge-like  or  concretion-like  forms,  as  the  cal- 
careous Algse  of  the  Yellowstone  Park.     Some  487. 
related  to  the  last-mentioned  occurring  in  warm 
waters  secrete  silica.    There  are  also  the  minute 
Coccoliths  over  the  ocean's  bottom  in  deep  or 
shallow  waters ;  they  are  so  named  from  the 
Greek  for  seed  and  stone. 


488 


488-493. 


Figs.  487-493,  DIATOMS  highly  magnified;  487,  A  group  of  fossil  Diatoms;  488,  Pinnularia  peregrins, 
Richmond,  Va. ;  489,  Pleurosigma  angulatum,  id.;  490,  Actinoptychus  senarius,  id. ;  491,  Melosira  eul- 
cata,  id. ;  a,  transverse  section  of  the  same ;  492,  Grammatophora  marina,  from  the  salt  water  at  Stoning- 
ton,  Conn.;  493,  Bacillaria  paradoxa,  West  Point. 

The  common  leathery  seaweeds  of  the  seacoast,  or  the  Fucus  division,  include  the 
Sargassum  of  the  Atlantic,  the  air-cavities  in  which  enable  it  to  float. 


CEPHALIZATION,    A    GENERAL    PRINCIPLE    BEARING    ON 
AND  GRADE   IN  THE   ANIMAL  KINGDOM. 


SYSTEM 


Since  an  animal  has,  typically,  an  anterior  nervous  mass  or  ganglion  determining  the 
position  of  the  head,  and  antero-posterior  conditions  in  growth,  a  greater  or  less  subordi- 
nation to  the  head  in  the  arrangement  of  its  organs  should  naturally  be  looked  for.  Degree 
of  structural  subordination  to  the  head  and  of  concentration  headward  in  body-structure, 
is  referred  to  under  the  term  Cephalization. 

The  principle  is  illustrated  in  the  class  of  Crustaceans,  with  special  clearness  and 
large  distinctive  characters,  on  account  of  the  fewness  of  the  species  and  their  size. 

Some  preliminary  explanations  are  here  first  given  respecting  Worms,  and  then  the 
facts  from  the  class  of  Crustaceans. 

1.  Worms.  —  An  example  of  a  low  decephalized  condition  among  Articulates  exists 
in  the  Tape-worm,  Tcenia  solium,  one  of  the  lowest  of  the  so-called  Worms.  It  grows  and 
elongates  by  the  multiplication  of  segments  (by  budding),  until  their  number  is  sometimes 
several  hundred,  the  new  segments  forming  successively  just  behind  the  head.  The  head 
has  its  very  small  nervous  ganglion,  from  which  slender  nerves  pass  backward  ;  so  that  in 
growth  and  nerves  it  is  an  individual.  But  it  has  no  mouth,  and  the  body  no  stomach  or 
intestine.  Instead  of  this,  each  segment  is  so  far  complete  in  its  individuality  that  it  takes 
its  independent  nutriment,  and  has  its  own  reproductive  system ;  and  if  separated  from 
the  rest  of  the  series,  it  has  all  that  is  required  for  propagating  the  species  by  ova.  Here 


438  HISTORICAL   GEOLOGY. 

decephalization  and  a  multiplicate  or  nearly  limitless  segmentation  are  extreme.  There  is 
no  lower  extreme,  except  in  that  of  the  compound  mass  of  the  sponge  or  the  polyp,  where 
-a  head  fails  entirely. 

In  the  higher  typical  Worms,  the  Annelids,  the  many  segments  of  the  body  have  a 
separate  nervous  ganglion  as  an  enlargement  of  the  nervous  cord,  or  pair  of  cords,  that 
passes  posteriorly  from  the  cephalic  ganglion,  giving  it  a  degree  of  independence.  But  the 
head  has  its  mouth,  and  the  body  its  intestine  and  reproductive  system,  so  that  the 
structure  is  one  in  system  of  growth  and  reproduction.  Yet  the  number  of  body-segments 
varies  greatly,  it  being  not  often  fixed  even  for  the  species  of  a  genus ;  and  all  of  the 
segments  behind  the  head  participate  alike  essentially  in  the  work  of  locomotion.  The 
body  structure  in  Worms  is,  therefore,  multiplicate,  and  greatly  decentralized,  and  loco- 
motion is  of  the  diffuse  kind.  Moreover,  jointed  limbs  are  wanting. 

2.  Crustaceans.  —  Crustaceans  contrast  strongly  with  the  Worms,  high  or  low.  (1)  The 
body  consists  of  a  head  (which,  as  in  other  animals,  includes  the  mouth  as  well  as  the 
organs  of  the  senses),  a  thorax  furnished  with  limbs,  and  an  abdomen.  (2)  The  number 
of  body-segments,  in  typical  species,  is  limited,  instead  of  being  multiplicate,  it  not 
exceeding  20;  6  of  these  segments  pertain  to  the  abdomen,  and  14  to  the  thorax  and 
head. 

On  differences  in  the  arrangement  and  functions  of  the  parts  of  the  structure, 
exemplifying  degrees  in  cephalization,  is  based  the  accepted  system  of  classification  in 
Crustaceans.  This  system  subdivides  the  typical  species  into  (1)  Decapods,  or  the 
10-footed,  and  (2)  Tetradecapods,  or  the  14-footed ;  and  each  of  these  tribes  into  two 
subordinate  groups,  Brachyurans  and  Macrurans  for  the  former,  and  Isopods  and 
Amphipods  for  the  latter. 

Decapods  and  Tetradecapods. — In  the  Decapods  (1)  the  head  includes  9  body- 
segments —  the  3  anterior  bearing  the  organs  of  the  senses,  the  eyes,  and  2  pairs  of 
antennae,  and  the  remaining  6,  the  jointed  mouth  organs  ;  and  (2)  the  thorax,  comprising 
the  remaining  5  segments  of  the  cephalothorax,  bearing  5  pairs  of  feet.  In  the  Tet- 
radecapods, the  head  corresponds  to  only  7  body-segments,  and  has,  therefore,  but  4  pairs 
of  mouth  organs,  while  the  thorax  includes  7  segments  and  bears  7  pairs  of  feet.  In  other 
words,  the  anterior  2  pairs  of  feet  of  the  Tetradecapods  are  pairs  of  mouth  organs  in  the 
Decapods.  There  is  thus  a  transfer  forward  of  legs  to  the  mouth  series  on  rising  from 
the  Tetradecapod  tribe  to  the  Decapod.  It  is  a  case  of  concentration  headward  in  the 
structure,  or  of  higher  cephalization.  The  two  tribes  also  differ  in  the  mean  size  of 
the  animals,  Decapods  having,  on  an  average,  100  times  the  bulk  of  Tetradecapods. 

We  pass  now  to  the  two  subdivisions  of  the  Decapods  and  Tetradecapods. 

Brachyuran  and  Macruran  Decapods.  —  A  Macruran  Decapod,  as  exemplified  in  a 
Lobster,  Prawn,  or  Shrimp,  has  (1)  an  elongate,  loosely  compacted  body,  with  the 
abdomen  nearly  as  long  as  the  cephalothorax,  and  in  some  species  several  times  longer ; 
(2)  the  abdomen  is  the  most  powerful  organ  in  locomotion  ;  (3)  the  thoracic  feet  are 
feeble  in  locomotion  ;  (4)  the  outer  mouth  organs  are  foot-like,  free,  and  long ;  (5)  the 
antennae  are  sometimes  a  foot  or  more  long. 

The  Brachyuran,  as  the  common  Crab,  has,  on  the  contrary,  (1)  a  short  body,  it 
being  seldom  longer  than  broad  ;  (2)  the  abdomen  in  males  is  very  small  and  narrow, 
it  doing  no  service  in  locomotion,  but,  instead,  lying  confined  in  a  groove  on  the  under 
side  of  the  body,  so  that  the  animal  is  almost  comprised  within  the  first  14  of  the  normal 
20  segments  of  the  Crustacean  ;  (3)  the  thoracic  feet,  or  those  of  the  posterior  5  of 
these  14  segments,  are  the  sole  organs  of  locomotion ;  besides  (4)  the  mouth  organs  are 
small,  and  closely  stowed  away  together  within,  or  over,  a  shallow  cavity,  which  is 
covered  by  the  outer  pair,  as  an  operculum  ;  and  (5)  in  harmony  with  the  general  com- 
pactness of  structure,  the  antennae  are  very  small,  seldom  exceeding  an  inch  in  length. 


BRIEF   REVIEW   OF   THE   SYSTEM   OF   LIFE.  439 

Between  the  Macrurans  and  the  Brachyurans  there  is  the  grand  distinction  that  the 
former  are  long  extended  posteriorly,  and  urosthenic,  as  regards  locomotion  (or  strong  in 
the  posterior  extremity,  that  is,  the  abdomen),  while  the  latter  have  short  bodies,  gathered 
in  closely  and  compactly  behind  the  cephalic  ganglion,  and  are  podosthenic,  thoracic  feet 
being  the  only  locomotive  organs.  In  rising  from  the  Macruran  to  the  Brachyuran  there 
is  a  forward  transfer  in  the  general  structure  and  in  the  locomotive  function,  and  thus  a 
great  rise  in  degree  of  cephalization. 

Under  each  of  these  two  types  of  Decapods  a  wide  range  of  grade  is  structurally  indi- 
cated, illustrating  degrees  in  cephalization. 

Isopod  and  Amphipod  Tetradecapods.  —  The  Isopods  and  Amphipods  are  brachyuran 
and  macruran  Tetradecapods,  for  the  series  of  Tetradecapods  is  closely  parallel  with  that 
of  the  Brachyurans  and  Macrurans  among  Decapods.  The  Isopods  have  a  compact  body, 
a  short  abdomen,  which  is  not  used  in  locomotion,  with  relatively  short  antennae,  while 
the  Amphipods  have  a  longer  body  more  loosely  put  together,  usually  long  antennae,  an 
elongate  abdomen,  and  the  abdomen  is  the  chief  organ  of  locomotion  —  that  by  which  the 
little  animal  makes  its  leaps.  Here,  again,  the  lower  are  the  urosthenic  and  decephalized 
species,  the  higher  the  podosthenic  and  more  cephalized  species. 

Entomostracans. —  Below  the  Tetradecopods  come  the  Entomostracans.  A  part  of 
the  Entomostracans  are  multiplicate  species,  —  the  Phyllopods  ;  and  in  this  character, 
both  in  the  Entomostracans  of  Decapod  and  of  Tetradecapod  relations,  they  show  out 
the  ancestral  worm,  and  thereby  low-grade  cephalization.  The  structure  is  eminently 
primitive  and  was  especially  characteristic  of  early  Paleozoic  Articulate  life. 

Besides  these  there  are  the  simply  defective  forms  among  Entomostracans,  representa- 
tive of  different  stages  in  embryonic  development.  Defective  forms  of  similar  character 
occur  even  among  the  Macruran  Decapods  ;  for  some  of  the  inferior  shrimp-like  species 
have  one  or  two  of  the  posterior  segments  of  the  thorax  without  legs,  or  even  wanting ; 
and  in  such  species  (called  Schizopods),  the  thoracic  legs  have  the  form  characterizing 
a  young  stage  in  development.  But  among  the  Entomostracans,  the  defective  stage 
appears  in  more  extreme  forms.  The  limbs  are  partly  natatory ;  the  mouth  organs  are 
often  either  pediform  or  natatory,  or  of  more  abnormal  forms ;  and  the  abdomen  has 
no  appendages  except  ovarian  attached  to  the  basal  portion  and  a  caudal  pair  pertaining 
to  the  sixth  segment. 

The  preceding  remarks  on  the  bearing  of  the  principle  of  cephalization  on  system  and 
grade  in  Crustaceans  cannot  be  true  for  one  branch  of  the  Animal  Kingdom  without  hav- 
ing a  wide  significance.  See,  for  other  examples,  Historical  Geology,  pages  721,  723. 

This  subject  has  much  interest  in  connection  with  the  successional  lines  in  the  animal 
life  of  the  globe  which  geology  has  brought  to  light.  But  the  preceding  remarks  are  not 
to  be  understood  as  intimating  anything  with  regard  to  the  origin  of  species.  There  was 
no  such  reference  in  the  author's  first  presentation  of  the  views  in  1852. 1  At  that  time  the 
idea  of  evolution  by  natural  causes  had  scarcely  an  advocate  ;  for  Darwin's  work  did  not 
appear  until  1859.  Neither  are  the  facts  now  to  be  regarded  as  adding  to  the  causes  of 
derivation.  This  much,  however,  may  be  learned  from  them  :  — 

1.  Whatever  the  natural  causes  or  methods  concerned  in  evolution,  organic  conditions 
have  determined  lines,  limits,  and  parallel  relations,  in  accordance  with  the  principle 
of  cephalization. 

2.  In  the  evolution  of  the  animal  kingdom  a  "  tendency  upward  "  is  a  necessary  con- 
sequence of  the  presence  of  a  cephalic  nervous  ganglion  or  brain. 

-1  Report  on  Crustacea  of  the  Wilkes  Expl.  Exped.  around  the  World,  1618  pp.,  4to,  with  a 
folio  Atlas  of  96  plates.  In  the  papers  on  cephalization  published  in  the  American  Journal 
of  Science,  eleven  to  twelve  years  later,  and  subsequently  a  summary  in  1876,  the  principle 
of  cephalization  was  illustrated  by  reference  to  other  classes  of  animals ;  but  the  speculative 
conclusions  added  in  those  papers  are  not  all  in  accord  with  the  author's  present  judgment. 


I.     ARCH^AN   TIME. 

SYNONYMY.  —  Primitivgebirge,  Urgebirge,  Lehmann,  1756,  Werner.  Urformation.  Ur- 
gneissformation.  Azoic  Rocks,  Murchison  and  De  Verneuil,  1845,  Russia  in  the  Urals,  i. 
10.  Fundamental  Gneiss,  Lewisian  Gneiss,  and  later,  Laurentian  Gneiss,  after  Logan, 
Murchison.  Mona  Series,  De  La  Beche,  Geol.  Obs.,  p.  xxxii,  1851,  for  crystalline  rocks  of 
Anglesea,  etc.  Azoique,  D'Orbigny,  Pal.  et  Geol.,  1851.  Azoic  System,  J.  D.  Whitney,  Rep. 
of  Foster  and  Whitney,  Geol.  Lake  Superior  Land  District,  Part  ii.,  pp.  8-35,  1851,  the 
system  comprising  rocks  north  of  Lake  Superior,  others  south  of  the  lake,  also  others  in 
the  Adirondacks,  etc.  Laurentian  and  Huronian,  Logan,  1852,  1854.  Azoic  (following 
Whitney,  with  Logan's  subdivisions),  first  edition  of  this  Geology,  1863.  Archaean, 
D.,  Amer.  Jour.  Sc.,  viii.  213,  1874,  and  second  edition  Geology,  1875.  Eozoic,  J.  W. 
Dawson,  1875.  Crystallophyllian,  Belg.  Geologists  of  the  Internat.  Congr.  Geol.,  1885. 

Archaean  time  commences  geologically  with  the  earth  as  a  solid  globe,  or 
one  having  at  least  a  solid  exterior ;  for  only  the  conditions  of  such  a  globe 
are  within  reach  of  geological  investigation.  By  following  the  lead  of  ascer- 
tained law  in  physics  and  chemistry,  and  the  suggestions  of  astronomy,  and 
also  such  analogies  as  are  afforded  by  later  geological  history,  some  probable 
conclusions  may  be  drawn  with  reference  to  earlier  time.  But  this  is  not  the 
place  for  their  discussion,  except  so  far  as  to  state  the  principal  steps  of 
progress.  The  following  is  a  general  view  of  the  natural  subdivisions  of 
Archaean  time. 

I.  The  Astral  aeon,  as  it  has  been  called,  or  that  of  the  fluid  globe  having 
a  heavy  vaporous  envelope  containing  the  future  water  of  the  globe  or  its 
dissociated  elements,  and  other  heavy  vapors  or  gases. 

II.  The  Azoic  aeon.     Without  life. 

1.  The  LITHIC  ERA  :  commencing  with  the  earth  a  solid  globe,  or  at  least 

solid  at  the  surface;  the  temperature  at  the  beginning  above 
2500°  F. ;  the  atmosphere  still  containing  all  the  water  of  the 
globe  (amounting  to  200  atmospheres,  according  to  Mallet,  1880), 
all  the  carbonic  acid  now  in  limestone  and  that  corresponding  to 
the  carbon  now  in  carbonaceous  substances  and  organic  sub- 
stances (probably  50  atmospheres),  all  the  oxygen  since  shut  up 
in  the  rocks  by  oxidation,  as  well  as  that  of  the  atmosphere  and 
of  organic  tissues.  The  time  when  lateral  pressure  for  crustal  dis- 
turbance and  orographic  work  was  begun ;  when  "  statical  meta- 
morphism"  or  that  dependent  on  heat  of  a  statical  source,  —  the 
earth's  mass  and  the  vapors  about  it,  —  began. 

2.  The  OCEANIC  ERA  :  commencing  with  the  waters  condensed  into  an 

ocean  over  the  earth,  or  in  an  oceanic  depression,  with  finally  some 
emerging  lands,  —  the  temperature  perhaps  about  500°  F.,  if  the 
atmospheric  pressure  was  still  50  atmospheres.  The  first  of 
tides  and  the  beginning  of  the  retardation  of  the  earth's  rotation. 
Oceanic  waves  and  currents  and  embryo  rivers  begin  work  about 
440 


ARCHAEAN  TIME.  441 

the  emerged  and  emerging  lands ;  the  large  excess  of  carbonic 
acid  and  oxygen  in  the  air  and  water  a  source  of  rock-destruction ; 
before  the  close  of  the  era,  the  formation  of  limestones  and  iron- 
carbonate  by  chemical  methods,  removing  carbonic  acid  from  the 
air  and  so  commencing  its  purification ;  the  accumulation  of  sedi- 
ments without  immediate  crystallization  or  metamorphism,  and 
thereby  the  beginning  of  the  earth's  supercrust. 

III.  The  Archaeozoic  aeon.     Life  in  its  lowest  forms  in  existence. 

1.  The  ERA  OF  THE  FIRST  PLANTS  :  Algae,  and  later  of  aquatic  Fungi 

(Bacteria),  commencing  with  the  mean  temperature  of  the  ocean 
at  possibly  150°  F.,  since  plants  now  live  in  waters  up  to  and  evsn 
above  180°  F.  Limestones  formed  from  vegetable  secretions,  and 
silica  deposits  from  silica  secretions ;  iron-carbonate,  and  perhaps 
iron  oxides  formed  through  the  aid  of  the  carbonic  acid  of  the 
atmosphere  and  water ;  large  sedimentary  accumulations,  where 
conditions  favored,  thickening  the  supercrust. 

2.  The  ERA  OF  THE  FIRST  ANIMAL  LIFE  :  mean  temperature  at  the 

beginning  probably  about  115°  F.,  and  at  the  end  90°  F.,  or  lower  ; 
limestones  and  silica  deposits  formed  from  animal  secretions ; 
deposits  of  iron-carbonate  and  iron-oxides  continued ;  large  sedi- 
mentary accumulations. 

The  sedimentary  or  stratified  beds  of  Archaean  time  are  the  oldest  and 
most  obscured  parts  of  the  geological  record.  Sooner  or  later  in  the  Arch- 
aeozoic era  "dynamical  metamorphism"  began,  or  metamorphism  dependent 
on  heat  from  a  dynamical  source,  that  is,  heat  generated  by  movements  in 
the  thickening  crust,  aiding  the  heat  still  in  the  earth's  mass,  or  statical 
heat.  Thereby,  during  a  crisis  of  upturning,  the  thick  accumulations  of 
sediment  became  metamorphic  or  crystalline  ;  but  the  statical  heat  was  still 
so  great  that  the  temperature  was  easily  made  that  of  fusion,  and  conse- 
quently the  fusing  of  fusible  sedimentary  beds  took  place  and  outflows 
through  openings  or  fissures  of  granite,  syenyte,  dioryte,  gabbro,  and  other 
like  rocks,  derived  severally  from  granitic,  syenytic,  diorytic,  and  gabbronitic 
or  related  sediments ;  but  deep-seated  igneous  effusions  may  not  have  been 
common,  for  strains  in  a  thin,  rather  hot  supercrust  might  extend  little 
below  it,  and,  moreover,  igneous  ejections  from  a  deep-seated  source  and 
through  volcanoes  reached  their  maximum  in  the  later  part  of  geological 
time. 

Although  these  eras  are  not  marked  off  in  the  rocks,  there  are  facts 
enough  to  prove  that  they  represent,  in  a  general  way,  the  system  of 
progress  in  Archaean  time.  Millions  of  years  must  have  elapsed  during 
the  cooling  from  over  2500°  F.  to  500°  F. ;  a  very  long  era  during  that 
from  500°  F.  to  150°  F. ;  and  another  long  era  during  that  from  150°  F.  to 
115°  F. ;  and  still  another  during  that  from  115°  F.  to  90°  F.  Archaean  time 
was  long,  immensely  long. 


442  HISTORICAL   GEOLOGY. 

The  subdivision  of  Archaean  time  into  Azoic  and  Archaeozoic,  here  used,  is  the  same 
as  that  of  the  edition  of  1874,  except  that  Archaeozoic  is  substituted  for  Eozoic.  The  limit- 
ing temperature  of  Archseozoic  time  is  doubtful  for  several  reasons,  and  especially  because 
of  the  uncertainty  as  to  the  destructive  excess  of  carbonic  acid  in  the  air  and  waters, 
and,  therefore,  as  to  the  possibility  of  the  existence  of  life. 

There  is  reason  to  believe  that  during  the  progressing  consolidation,  and  long  after- 
ward, when  the  heat  was  too  great  for  the  existence  of  limestones,  the  lime  now  in  the 
limestones  of  the  globe  was,  to  a  large  extent,  combined  with  silica,  making  silicates  and 
especially  the  lime-soda  feldspars,  labradorite  and  oligoclase,  the  soda  being  that  now  in 
the  ocean's  waters  —  minerals  that  may  be  made  artificially  by  fusing  together  the 
ingredients ;  and,  consequently,  that  rocks  of  the  basalt  and  dioryte  types,  which  con- 
tain these  feldspars,  were  among  the  most  common.  Pyroxene  was  present  through  the 
whole  era,  but  hornblende  only  in  the  later  part ;  for  pyroxene  is  easily  made  at  the 
high  temperature  of  fusion,  but  hornblende  only  under  aqueo-igneous  action  at  the  lower 
temperature  of  800°  to  1000°  F.  The  lime  silicates  would  have  used  up  a  large  part 
of  what  is  now  free  silica  or  quartz,  and  hence  the  igneous  rocks  would  have  been,  to  a 
great  extent,  without  quartz,  and,  in  this  respect,  like  the  most  of  those  that  come  up 
from  the  earth's  depth  through  volcanic  eruptions.  In  fact,  most  volcanic  rocks  are  por- 
tions of  the  Archaean  mass  constituting  the  earth's  interior.  Such  being  the  prevailing 
rocks  of  the  crust,  the  sedimentary  beds  would  have  been  largely  of  like  constituents. 

On  the  condition  of  the  primeval  globe,  see  further  Ebelmen,  1855  ;  Bischoff,  1863 ; 
T.  S.  Hunt,  1867,  1880.  On  subdivisions  of  Archaean  time,  D.,  1892. 


NORTH  AMERICA. 
DISTRIBUTION  OF  ARCHJEAN  AREAS. 

Archaean  areas,  or  those  whose  surface  rocks  are  of  Archaean  age,  and 
which  indicate,  therefore,  the  probable  position  of  the  dry  land  at  the  close 
of  Archaean  time,  have  their  widest  distribution  in  the  more  northern  por- 
tions of  the  continents  of  North  America,  South  America,  and  Europe. 

In  North  America  they  cover  a  very  large  area,  situated  mostly  north  of 
the  Great  Lakes  and  the  St.  Lawrence  River,  which  is  approximately 
V-shaped  in  its  southern  part,  as  shown  in  the  accompanying  map.  The 
white  areas  on  the  map  represent  the  probably  emerged  land  over  the  great 
Archaean  continental  sea.  The  great  northern  area  has  been  estimated  to 
contain  more  than  2,000,000  square  miles.  From  the  region  of  the  Great 
Lakes  a  broad  arm  stretches  northeastward  to  Labrador  and  beyond,  and 
another,  2000  miles  long,  northwestward  to  the  Arctic  shores.  Hudson 
Bay,  800  miles  from  north  to  south  and  600  in  greatest  breadth  lies  between 
the  arms  of  the  V.  The  eastern  arm  of  this  early  dry  land  of  North 
America  has  a  course  nearly  parallel  to  the  existing  eastern  coast-line  of 
the  continent,  and  the  western  as  nearly  to  the  mean  direction  of  the 
western  coast-line.  The  map  is  011  Mercator's  projection.  The  course  of 
the  Mississippi  River  and  the  outlines  of  lakes  are  inserted  merely  to  mark 
positions.  The  Archaean  area  extends  south  of  British  America  into  northern 
New  York,  the  Adirondack  region  being  a  portion  of  it,  and  also  south  of 
Lake  Superior  into  northern  Michigan  and  Wisconsin. 


AKCH^EAN   TIME. 


443 


Besides  the  nucleal  area  of  the  continent,  there  are  other  areas  lying 
in  ranges  or  chains  that  are  approximately  parallel  to  the  arms  of  the 
nucleal  V. 

On  the  Atlantic  border,  northeastward  in  general  trend.  —  On  the  Atlantic 
border  there  is  the  long  Appalachian  protaxis  (page  24),  extending  interrupt- 
edly from  Canada  south  of  the  St.  Lawrence,  along  the  higher  land  of  Ver- 

494. 


Map  of  North  America  at  the  close  of  Archaean  time,  showing  approximately  the  areas  of  dry  land. 

mont ;  eastern  Berkshire  in  Massachusetts ;  Putnam,  Orange,  and  Rockland 
counties  in  New  York,  and  Sussex  in  New  Jersey,  making  the  Highland 
Range,  which  crosses  the  Hudson  between  Fishkill  and  Peekskill ;  consti- 
tuting some  ridges  in  southeastern  Pennsylvania;  thence  continuing  south- 
westward  along  the  "  Piedmont "  belt,  and  through  Virginia  and  North 
Carolina,  constituting  in  the  latter  state  the  Black  Mountains ;  thence  into 
South  Carolina  and  Georgia.  It  is  marked  A  on  the  map. 

To  the  northeastward,  over  New  England  to  Newfoundland,  there  are 
other  parallel  ranges,  bounding  broad  valleys  or  basins,  as  follows :  (1)  To  the 
east  of  the  Connecticut  valley,  at  intervals,  from  Canada  to  Connecticut. 


444  HISTORICAL   GEOLOGY. 

(2)  Farther  east,  from  near  Chaleur  Bay,  on  the  Gulf  of  St.  Lawrence, 
through  New  Brunswick,  southwest  to  the  coast  of  Maine  (including  the 
Mount  Desert  rocks)  and  into  eastern  Massachusetts.  (3)  The  Acadian 
Eange,  along  western  Newfoundland  and  central  Nova  Scotia;  then  sub- 
merged off  the  coast  of  Maine  and  Massachusetts ;  then  over  southeastern 
Massachusetts,  and  probably  along  Long  Island.  (4)  A  central  Newfound- 
land range,  which  may  have  had  a  submarine  extension  along  Sable  Island 
and  the  shoals  about  it,  east  of  Nova  Scotia.  (5,  6)  Two  other  ranges 
farther  east. 

The  Acadian  is  the  longest  of  these  Archaean  ranges ;  it  is  the  chief  eastern 
belt  of  the  Archaean  on  the  Atlantic  border,  and  is  strictly  the  Acadian  pro- 
taxis.  Its  partial  submergence  is  not  in  doubt ;  for  besides  indications  of 
this  along  the  sea-bottom  south  of  Nova  Scotia,  there  is  proof  of  subsidence 
of  several  hundred  feet  in  the  fiords  of  Maine  and  the  coast;  in  the  Bay 
of  Fundy,  in  Massachusetts  and  Narragansett  bays,  and  in  Long  Island 
Sound.  The  combination  of  the  Acadian  and  Appalachian  protaxes  deter- 
mined the  existence  of  the  great  "  Middle  Bay "  of  the  Atlantic  Coast  (page 
210),  and  in  the  region  of  their  junction  lies  the  bay  of  New  York  with 
the  mouth  of  the  Hudson.  Thus  the  foundations  were  laid  in  Archaean 
time. 

On  the  Pacific  border,  northwestward  in  general  trend. — The  chief  Archaean 
ranges  on  the  Pacific  border  are  the  following :  (1)  The  Kocky  Mountain 
protaxis,  or  the  "  backbone  "  of  the  mountains.  It  extends  northward  and 
westward  nearly  to  53°  N.,  in  the  Peace  Kiver  region,  and  is  represented  be- 
yond in  isolated  areas.  It  bends  eastward  250  miles  south  of  49°  N.,  and  then 
extends  southward  and  westward  through  Colorado  into  New  Mexico.  The 
region  of  the  bend,  whence  go  off  eastward  and  westward  several  of  the  large 
rivers  of  the  continent,  is  the  locality  of  the  Yellowstone  Park.  Along  the 
west  side  of  the  Wasatch  Kange,  near  Salt  Lake,  the  Archaean  areas  appear 
to  be  parts  of  a  western  spur  of  the  protaxis,  nearly  in  a  line  with  the  part 
of  it  in  British  America.  To  the  westward  are  other  nearly  parallel  Archaean 
ranges,  in  the  Great  Basin ;  along  the  Sierra  Nevada  in  California  and  in  the 
Sierra  Madre  of  western  Mexico;  and  probably  in  the  Coast  and  Island 
belts  of  British  America.  In  addition,  isolated  areas  occur  east  of  the  Kocky 
Mountain  chain  in  the  Black  Hills  of  Dakota,  the  Iron  Mountain  region  of 
Missouri,  and  in  central  Texas.  Thus  the  oldest  land  areas  marked  out 
well  the  outlines  of  the  continent. 

There  is  a  landward  bend  in  Pennsylvania  of  the  Appalachian  protaxis, 
like  the  landward  bend  of  the  Kocky  Mountain  protaxis,  and  the  two  bends 
are  not  much  south  in  latitude  of  the  southern  end  of  the  nucleal  Archaean 
area  of  the  continent;  as  if  connected  in  origin  with  the  absence  farther 
south  of  outcropping  Archaean. 

Archaean  rocks  are  the  prevailing  rocks  of  the  portions  of  Greenland  free 
from  its  covering  of  ice,  and  they  make  a  large  part  also  of  Baffin  Land,  on 
the  opposite  side  of  Baffin  Bay. 


ARCHAEAN   TIME.  445 


SUBDIVISIONS  OF  THE  ARCHAEAN  TERRANES,  AND  THE  ROCKS. 

Subdivisions.  —  Two  subdivisions  have  general  acceptance  :  — 

I.  THE  LAURENTIAN. — Logan,  Rep.  GeoL  Canada,  for  1852-53;  named 
from  the  Laurentide  Mountains. 

II.  THE  HURONIAN  ERA.  —  Huronian  of  Logan  and  Murray,  Rep.  GeoL 
Can.,  for  1853-4-5,  in  the  special  report  for  1854 ;  Esquisse  du  GeoL  du  Can., 
1855.     "  Huron  Cupriferous  Formation  "  of  the  north  shore  of  Lake  Huron, 
Rep.  GeoL  Can.,  for  1847-8. — Part  of  Agnotozoic,  Irving,  1887,  the  Keweenaw 
group  of  the  Agnotozoic  being  referred  beyond  to  the  Paleozoic.     Part  of 
Algonkian,  Walcott,  1889 ;  a  name  proposed  as  a  substitute  for  Agnotozoic, 
and  so  accepted  by  geologists. 

The  subdivisions  were  based,  according  to  Logan,  on  relations  of  uncon- 
formity in  bedding  between  the  Huronian  and  Laurentian  terranes.  The 
Huronian  areas  recognized  were  situated  along  the  north  shore  of  Lake 
Huron,  and  at  points  on  the  north  and  east  shores  of  Lake  Superior. 
Archaean  rocks  vary  from  massive  crystalline  kinds,  like  granite,  syenyte, 
dioryte,  and  massive  gneisses,  to  the  thinnest  of  schists ;  and  include,  also, 
limestone,  quartzyte,  and  some  uncrystalline  sandstone  and  other  fragmental 
beds,  besides  large  beds  of  iron  ore.  The  Laurentian  division  in  the  vicinity  of 
the  lakes  was  observed  to  comprise  the  more  massive  kinds ;  and  the  Huronian, 
the  thinner  schists,  as  mica  schist,  chlorite  schist,  with  quartzyte.  With  this 
distinction  in  view,  the  Huronian  was  made  to  include  also  an  area  south 
of  Lake  Superior  extending  from  Marquette,  Mich.,  westward,  containing 
the  large  beds  of  iron  ore  of  that  region;  and  this  conclusion  has  since 
been  sustained  by  evidence  proving  their  unconformability  to  the  Archaean 
terranes  beneath.  But  most  other  references  of  areas  to  the  Huronian  that 
have  been  made  are  reasonably  questioned,  because  it  is  now  known,  as  stated 
on  page  458,  that  the  distinction  based  on  kinds  of  rocks  is  not  a  safe  cri- 
terion of  geological  age.  Among  metamorphic  Paleozoic  rocks,  massive, 
thick-bedded  and  thin-bedded  schists  are  associated  in  the  same  formation ; 
and  so  it  is,  beyond  doubt,  in  the  Huronian,  and  even  in  the  Laurentian.  Still, 
the  thinner  schists  of  the  Archaean  are  to  a  much  larger  extent  Huronian 
than  Laurentian ;  and  all  the  uncrystalline  Archaean  strata  are  Huronian. 

The  beds  of  iron  ore  have  so  great  thickness  in  some  regions,  that  the 
Archaean  has  been  called  the  Iron  Age  in  the  earth's  history. 

The  localities  of  Huronian  described  by  Logan  with  special  detail  in  the  Canadian 
Geological  Report  of  1863  are  as  follows :  (1)  to  the  west  of  the  Mississaga  River,  north 
of  Lake  Huron ;  (2)  to  the  eastward,  in  the  vicinity  of  White  Fish  and  Sturgeon  rivers  ; 
(3)  near  Lake  Temiscaming,  15(Tmiles  northeast  of  the  last  locality ;  and  a  few  miles  from 
Michipicoten  Island,  north  of  Lake  Superior.  The  iron-bearing  rocks  south  of  Lake 
Superior  about  Marquette  and  to  the  westward  are  referred  to  the  same  period  on  the 
colored  map  in  the  octavo  Atlas  accompanying  the  Report,  published  in  1863,  after  inves- 
tigations by  Murray. 


446  HISTORICAL   GEOLOGY. 

Murray  refers  to  the  Huronian  also  diorytes,  slates,  quartzytes,  and  conglomerates,  that 
occur  in  the  peninsula  of  Avalon,  southeastern  Newfoundland,  and  describes,  from  the 
upper  division,  a  fossil  of  uncertain  relations  which  he  names  Aspidella  Terra-novica,  and 
also  a  worm  burrow  referred  to  the  genus  Arenicolites.  The  gneisses  of  the  region  he 
calls  Laurentian. 

The  structure  and  relations  of  the  Huronian  along  the  iron-bearing  belt  from  Mar- 
quette  to  Penokee  in  Wisconsin  (including  the  Penokee-Gogebic  range,  and  the  Menominee 
iron  region)  have  been  studied  with  care  by  Irving  and  Van  Hise.  Van  Hise  and  Pumpelly 
have  recognized  a  subdivision  of  the  Huronian  north  and  south  of  the  lakes,  on  the  ground 
of  a  stratigraphical  break,  into  Upper  and  Lower  Huronian. 

In  most  cases,  kinds  of  rock  have  had  chief  importance  in  the  subdivision  of  the 
Archaean.  T.  S.  Hunt  proposed  the  division  of  the  Archaean  (commencing  below)  into 
Laurentian,  Norian,  Arvonian  (of  Hicks),  Huronian,  Montalban,  Taconian.  The  Montal- 
ban  includes  the  White  Mountain  micaceous  gneiss  ;  and  the  Taconian,  the  rocks  of  the 
Taconic  series  now  known  to  be  of  Paleozoic  age.  C.  H.  Hitchcock  in  his  Report  on  the 
geology  of  New  Hampshire,  adopts  the  subdivisions,  beginning  below :  Laurentian,  Mon- 
talban (or  Atlantic,  including  granites,  gneisses,  etc.),  Labradorian,  and  Huronian.  A.  C. 
Lawson,  from  his  Canada  studies  about  the  Lake  of  the  Woods,  Rainy  Lake,  and  else- 
where, has  divided  the  terranes  above  the  Laurentian  into  the  Coutchiching  (mica  schists 
and  gneisses)  and  Keewatin  (thinner  schists  with  conglomerates  and  some  iron  ore),  and 
to  the  two  united  he  has  given  the  name  Ontarian ;  the  term  Huronian  is  not  used. 
A.  Winchell  arranges  the  Marquette  iron  region  below  the  true  Huronian  in  a  group  called 
the  Marquettian.  The  Laurentian  Gneissic  group  underneath  is  made  88,000  feet  thick. 
N.  H.  Winchell  refers  the  original  Huronian  beds  on  the  north  shore  of  Lake  Superior 
to  the  Lower  Cambrian  ;  and  makes  the  Archaean  of  Minnesota  to  include  three  divisions  : 
(1)  the  Laurentian  gneiss  and  related  rocks  ;  (2)  the  Vermilion  schists,  partly  hornblendic 
schists  (equivalent  to  the  Coutchiching  of  Lawson)  ;  (3)  the  Keewatin  schists,  which  are 
iron-bearing.  The  Animikie  beds,  consisting  of  chlorite  schist,  slates,  sandstones,  and 
small  beds  of  iron  ore,  having  in  general  small  dip,  have  been  referred  to  the  Huronian  by 
Logan,  Irving,  and  Van  Hise,  but  to  the  Cambrian  by  Selwyn,  Winchell,  and  others  ;  and 
Selwyn  has  announced  the  discovery  in  it  of  markings  which,  according  to  G.  F.  Matthew, 
are  tracks  much  like  the  tracks  of  an  animal  found  in  the  Middle  Cambrian  of  St.  John, 
New  Brunswick.  The  Mesabi  Range  with  its  large  beds  of  iron  ore  is  made  Cambrian 
by  Winchell.  The  Archaean  rocks  of  central  Texas  are  divided  by  T.  B.  Comstock 
(1890)  into  the  Burnetan  and  Fernandian,  corresponding  apparently  to  the  Laurentian 
and  Huronian.  The  latter  section  is  described  as  containing  large  beds  of  magnetite. 
Overlying  beds  in  which  no  fossils  have  been  found  he  calls  Eparchaean.  M.  E.  Wads- 
worth  has  announced  (1892)  the  following  subdivisions  of  the  Archaean  in  northern 
Michigan:  (1)  Cascade,  (2)  Republic,  (3)  Mesnard,  (4)  Holyoke,  and  (5)  Negaunee 
formations  ;  2  and  3  corresponding  to  the  Lower  Marquette,  and  4  and  5  to  the  Upper. 

Van  Hise,  in  1893,  proposed  to  restrict  the  term  Laurentian  to  granite-gneisses  —  a 
petrological  distinction ;  and  gave  to  a  supposed  second  division  of  the  Archaean,  the 
term  Mareniscan,  derived  from  the  name  of  a  township  in  Michigan. 

A  bibliography  of  the  American  Archaean  to  1884,  with  various  notes,  is  contained  in 
the  "Azoic  System,"  by  Whitney  and  Wadsworth,  pages  331-566  of  vol.  vii.  of  the  Bull. 
Mus.  Comp.  Zool.,  Cambridge,  1886.  A  full  bibliography,  coming  down  to  1892,  is  pub- 
lished in  the  Report  on  the  "  Archaean  and  Algonkian,"  by  C.  R.  Van  Hise  (1892),  con- 
stituting Bulletin  No.  86  of  the  U.  8.  Geol.  Survey.  The  latter  work  contains  brief 
abstracts  of  the  publications  noticed,  a  full  exposition  of  the  views  entertained,  and  the 
author's  own  conclusions  at  length.  The  distinguishing  characteristics  of  the  subdivisions 
proposed  by  Hunt,  Lawson,  and  others  are  given  in  this  Report  with  much  fullness  ;  and 
all  investigators  of  Archaean  terranes  should  have  a  copy  of  it  at  hand.  The  subject  is  in 
an  unsettled  state,  with  wide  divergences  in  opinion  among  investigators. 


ARCHAEAN   TIME.  447 

i 

Algonkian  formation.  —  The  Algonkian  formation  (Agnotozoic  of  Irving)  is  made  by 
its  describers  to  include  the  Huronian  of  Logan,  north  and  south  of  the  lakes,  and  some  of 
the  so-called  Huronian  in  other  regions.  Its  rocks  (1)  comprise  the  thinner  schists,  semi- 
crystalline  slates,  quartzytes,  and  uncrystalline  fragmental  and  shaly  rocks  ;  and  (2)  they 
are  of  pre-Cambrian  age.  The  supplanting  of  the  older  name,  Huronian,  by  the  newer 
is  not  sustained  by  any  rules  of  nomenclature.  It  has  been  given  a  wider  range  by  includ- 
ing under  it  the  Keweenaw  copper-bearing  sandstone  formation,  which  lies  unconformably 
on  the  Huronian,  and  this  change  of  limit  was  one  reason  for  the  change  of  name. 

T.  B.  Brooks  first  recognized  the  "  Keweenawian  "  as  a  distinct  system  of  rocks 
(1876)  ;  Irving  called  it  Keweenawan.  If  Archaean  instead  of  Paleozoic,  it  marks  a 
Keweenawian  period  in  the  long  Huronian  era.  The  Keweenaw  formation  is  without 
fossils,  and  hence  is  of  uncertain  age ;  but  its  relations  appear  to  be  probably  Paleozoic, 
as  explained  beyond. 

Some  of  the  localities  of  Algonkian  observed  by  Walcott  are  the  following :  (1)  the 
tilted  beds  of  quartzytes  and  siliceous  slates  at  the  base  of  the  Wasatch  series,  lying  con- 
formably beneath  the  Lower  Cambrian ;  and  (2)  strata  beneath  the  Cambrian  in  the  Eureka 
District  and  elsewhere  in  Nevada,  where  there  is  the  same  conformability.  The  beds  are 
described  as  very  thick  and  as  affording  no  fossils  ;  but  the  conformability  to  the  Cambrian 
suggests  the  query  whether  the  beds  are  not  lowest  Cambrian.  (3)  At  the  base  of  the  walls 
in  Grand  Canon  of  the  Colorado,  lying  unconformably  beneath  Upper  Cambrian  beds,  up- 
turned beds  of  sandstone, shale,  and  limestone,  named  by  G.  K.  Gilbert,  the  Tonto  group. 
The  presence  of  fossils  in  some  of  the  Tonto  beds  (including  remains  of  a  Stromatoporid, 
a  Trilobite,  and  a  Hyolithes,  and  a  Discina-like  shell)  shows  that  part,  at  least,  of  the  Tonto 
group  is  not  Algonkian,  and  renders  it  probable  that  all  is  Paleozoic.  (4)  In  central  Texas, 
Llano  County,  beneath  Upper  Cambrian  strata  and  over  the  Archaean,  a  formation  which 
is  called  the  Llano  group.  (5)  Part  of  the  Huronian  of  southeastern  Newfoundland, 
described  by  Murray,  which  Walcott  states  is  unconformable  to  the  overlying  Olenellus 
beds.  (6)  Below  the  Potsdam  series  in  the  Adirondacks.  These  are  some  of  the  local- 
ities of  the  so-called  Algonkian  formation. 

The  facts  respecting  the  Algonkian  are  reviewed  hi  Van  Hise's  Report  of  1892,  men- 
tioned above  ;  also  briefly,  on  some  localities,  in  Walcott' s  Correlation  of  the  Cambrian, 
U.  S.  Geol.  Survey,  Bulletin  No.  81,  1891. 

Kinds  of  rocks.  —  The  more  characteristic  kinds  of  Archaean  rocks  are 
coarse  granites ;  thick-bedded  gneisses,  especially  hornblendic  varieties,  sye- 
nytes,  diorytes,  and  pyroxeuic  varieties  of  these  rocks ;  the  granite-like  rock 
of  the  basalt  type,  called  gabbro ;  and  each  of  these  rocks  under  gneissic  and 
thin-schistose  varieties.  Zircon-syenyte  is  rather  common.  There  are  also 
chrysolite  rocks  and  chrysolitic  varieties  of  some  of  the  above  kinds  ;  and 
with  them,  serpentine  rocks,  the  serpentine  being  a  result  of  the  alteration 
of  chrysolite  or  pyroxene  and  possibly  of  some  other  mineral  containing 
magnesia. 

Crystalline  limestone  (usually  dolomyte  or  magnesian  limestone)  is 
common  in  some  regions ;  and  it  often  contains  large  crystals  of  apatite 
(calcium  phosphate)  and  the  pale  yellow  mineral,  chondrodite  (a  fluorine- 
bearing  magnesium  silicate),  supposed  to  be  peculiar  to  the  Archaean, 
besides  many  other  minerals. 

There  are  also  in  the  Laurentian  series,  but  less  abundantly,  horn- 
blende schist,  mica  schist,  hydromica  (or  sericite)  schist,  chlorite  schist, 
and  quartzyte. 


448 


HISTORICAL   GEOLOGY. 


The  massive  rocks  (whether  Laurentian  or  Huronian)  are  generally 
igneous ;  but,  most  probably,  for  reasons  already  stated,  metamorphic 
igneous  to  a  greater  extent  than  deep-seated  igneous.  The  granite  and 
syenyte  often  contain  great  masses  and  long  broken  strips  of  schists, 
or  constitute  dike-like  intrusions.  Figures  495,  496  of  portions  of  the 
rocks  at  Burntside  Lake,  in  northeast  Minnesota,  are  from  A.  Winchell's 
Field  Studies  in  the  Archuean  Rocks  of  Minnesota.  In  these  examples, 
granite  and  mica  schist  are  the  two  rocks  combined.  In  other  figures, 
syenyte  has  the  place  of  granite,  and  the  schist  is  a  hornblende  schist. 


496. 


Mica  schist  (the  lined  areas)  and  granite ;  at  m  the 
two  intimately  mixed.  Surface,  12  feet  square. 
A.  Winchell,  '87. 


Mica  schist  and  granite.    Surface,  12  feet  square. 
A.  Winchell,  '87. 


Often  the  massive  rock  contains  only  isolated  blocks ;  and  from  this  con- 
dition there  are  all  gradations  to  those  represented  in  the  figures.  The 
rock  fragments  are  not  widely  scattered,  like  those  torn  from  the  walls  of  a 
fissure  by  ascending  lava,  but  often  are  still  nearly  in  their  original  lines. 
In  cases  like  those  above  described,  the  conclusion  seems  unavoidable  that 
the  extrusion  of  the  melted  rock  followed  closely  on  a  general  fracturing  of 
the  beds  that  are  now  schist,  and  that  this  could  have  happened  only  at 
an  epoch  of  metamorphism,  during  the  progress  of  a  great  upturning,  when 
some  one  or  more  of  the  strata  in  a  thick  series  of  formations  became  fused 
by  the  excessive  heat,  and  was  forced  up  into  fissures  or  spaces  opened  in 
the  flexed  and  fractured  unfused  strata.  The  liquid  did  not  make  the 
fractures,  but  these  being  made,  it  flowed  in  and  filled  all  crevices.  In 
other  places,  described  by  Winchell,  and  especially  in  the  vicinity  of 
Saganaga  Lake,  the  granites  and  the  associated  gneiss  contain  rounded  peb- 
bles every  rod  or  two,  two  to  six  inches  in  diameter ;  and  at  one  locality  the 
pebbles,  though  not  in  contact,  were  "  in  such  abundance  as  to  constitute  a 


ARCHAEAN   TIME.  449 

real  conglomerate,"  giving  evidence  of  "attrition,"  "fragmental  accumula- 
tion," and  subsequent  metamorphism.  The  rounded  stones  were  four  to  five 
inches  through,  and  consisted  of  crystalline  augitic  and  other  rocks. 

In  the  recognized  Huronian  areas  on  the  north  shore  of  Lake  Huron, 
and  in  the  Penokee-Marquette  belt,  south  of  Lake  Superior,  extending 
from  Wisconsin  into  northern  Michigan,  the  rocks  are  quartzyte,  siliceous 
schist,  sandstones,  conglomerates,  micaceous  and  chloritic  slates,  chloritic 
greenstone,  dioryte ;  and  in  Wisconsin  there  is  a  cherty  limestone  at  the 
base,  and  carbonaceous  as  well  as  graphitic  shales  above. 

A  common  feature  of  Archaean  rocks,  or  at  least  of  their  veins,  is  the  frequent  occurrence 
of  minerals  containing  rare  elements,  as  niobium,  tantalum,  lanthanum,  thorium,  yttrium, 
zirconium,  caesium,  rubidium,  and  others.  The  following  minerals  are  common  in 
Archsean  rocks,  or  their  veins:  nephelite  (elseolite),  cancrinite,  sodalite,  spinel,  chryso- 
beryl,  danburite,  amblygonite,  spodumene,  petalite,  microlite,  gadolinite,  cryolite,  besides 
others.  But  garnet,  mica,  andalusite,  cyanite,  staurolite,  are  less  common  than  in  later 
crystalline  rocks.  Chondrodite  is  usually,  if  not  always,  Archsean. 

In  the  Kent-Cornwall  ridge,  west  of  Kent,  Conn.,  and  in  the  high  land  east  of 
Tyringham,  Lee,  and  Pittsfield,  Mass.,  occur  chondroditic  limestones,  like  that  of  Sussex 
County,  N.J.,  and  at  a  locality  east  of  South  Lee,  near  the  junction  of  the  Archaean 
rocks  with  the  Cambrian  quartzyte,  masses  of  chondrodite  occur  as  large  as  the  fist. 

One  of  the  most  characteristic  features  of  the  Archsean  is  the  occurrence 
of  great  beds  of  valuable  iron  ore,  some  of  them  100  to  400  feet  thick.  They 
are  found  of  great  thickness  in  Canada,  northern  and  southeastern  New 
York,  northern  New  Jersey,  and  the  region  south  through  Virginia  to 
Georgia;  in  the  Penokee-Marquette  belt,  south  of  Lake  Superior;  the 
Missouri  Iron  Mountain  region;  also  in  Utah,  Wyoming,  Colorado,  New 
Mexico,  and  Arizona,  and  elsewhere. 

The  ores  are  usually  magnetite,  hematite,  and  titanic  iron,  of  bright, 
lustrous  kinds;  and  in  one  region,  in  Sussex  County,  N.J.,  it  is  a  zinc- 
manganese  iron  ore,  called  franklinite,  mixed  with  disseminated  zinc  oxide 

497.  498.  499. 


Northern  Michigan,  Whitney.  Essex  County,  N.Y.  Essex  County,  N.Y. 

Kmmons.  Emmons. 

and  zinc  silicate.  But,  besides  these  kinds,  there  is  also  iron  carbonate  or 
siderite. 

Figs.  497  to  499  show  some  of  the  positions  of  the  ore-beds  in 
metamorphic  schists,  the  black  beds  i  being  the  ore-beds,  and  the  ore 
magnetite  or  hematite. 

In  Fig.  497,  the  ore-beds  (of  northern  Michigan)  are  between  beds  of 
DANA'S  MANUAL  —  29 


450  HISTORICAL   GEOLOGY. 

chlorite  schist  and  dioryte,  and  have  jaspery  bands.  In  497,  499,  from 
Essex  County,  N.Y.,  the  associated  rock  is  gneiss,  and  the  ore-bed  is 
interlaminated  with  quartz.  At  one  Essex  County  mine,  the  ore-bed  is  150 
feet  thick ;  at  the  Cranberry  mine,  on  the  borders  of  North  Carolina  and 
Tennessee,  400  feet.  Grains  of  calcium  phosphate  (apatite)  are  often 
disseminated  through  the  ore. 

Iron  carbonate  is  associated  with  the  oxides  south  of  Lake  Superior.  It 
occurs  only  sparingly  to  the  eastward  in  Michigan,  south  of  Lake  Superior, 
at  the  Marquette  mine,  but  more  abundantly  to  the  westward  in  Wisconsin. 
The  metamorphism  of  the  beds,  correspondingly,  is  least  to  the  westward. 
The  carbonate  is  the  ore  originally  laid  down,  and  the  hematite  and  magne- 
tite are  results  of  metamorphic  change,  in  which  the  carbonic  acid  was  ex- 
pelled. 

In  eastern  Canada  and  along  the  Archaean  pro  taxis,  southward  through  New  York, 
New  Jersey,  and  beyond,  the  carbonate  is  wholly  absent,  the  iron  ores  being  magnetite, 
hematite,  or  titanic  iron.  Moreover,  the  thickness  of  the  ore-beds  is  far  greater  and  the 
metamorphism  of  the  region  is  of  higher  grade,  —  thick-bedded,  massive,  and  schistose, 
crystalline  rocks  prevailing.  Notwithstanding  these  differences,  the  eastern  iron-bearing 
series  may  be  Huronian,  and  unconformable  to  adjoining  Laurentian,  but  the  evidence  of 
this  has  not  been  obtained.  The  same  belts  have  their  thick  beds  of  crystalline  limestone, 
often  chondroditic,  and  in  this  respect  rocks  of  the  Appalachian  protaxis  differ  from  those 
of  the  Lake  Superior  region.  The  course  of  the  Appalachian  chain  was  the  region  in 
later  time  of  thick  sedimentary  deposits,  great  upturnings,  intense  metamorphism,  while, 
cotemporaneously,  little  change  was  in  progress  over  the  Mississippi  Valley  ;  and  it  may 
be  that  the  same  kind  of  difference  distinguished  the  two  regions  in  Archaean  time. 


STRUCTURE,   THICKNESS,  AND  ORIGIN  OF  THE  ROCKS. 

As  is  implied  in  the  preceding  descriptions,  part  of  the  rocks  are  massive, 
as  granite,  syenyte,  dioryte,  gabbro ;  and  a  large  part  are  schistose  and  dis- 
tinctly stratified ;  and  into  the  schistose  the  massive  often  graduate.  The 
alternations  of  ore-beds  with  schists,  quartzyte,  limestones,  in  sections  like 

those  figured  above,  are  evidence  of  strati- 
fication, and,  therefore,  of  the  succes- 
sive formation  of  the  beds,  whether  now 
crystalline  or  not.  The  quartzytes  are  old 
sandstones;  the  limestones  deposited  beds 
interstratified  limestone,  St.  Lawrence  of  iimest0ne,  either  of  organic  or  chemical 

County,  N.Y.     Kmmons. 

origin ;  and  the  schists  are  fragmental  beds 

in  a  metamorphic  condition.  In  Fig.  500  a  stratum  of  limestone,  I,  is  overlaid 
by  strata  of  gneiss,  a,  a,  and  steatyte,  b.  Such  sections  could  be  multiplied 
indefinitely.  The  following,  by  Logan,  Fig.  501,  which  is  partly  ideal,  but 
not  untrue,  represents  white  granular  or  crystalline  limestone,  a,  many 
times  folded  and  interstratified  with  gneiss  and  quartz  rock,  b ;  and  the 
limestone  has  been  traced  over  the  same  region  (Grenville  and  the  adjacent 
country,  Canada),  in  the  linear  and  curving  bands  of  a  series  of  great 


ARC H^E AN   TIME.  451 

flexures.  The  facts  prove  that  the  beds  were  laid  down  horizontally  over 
large  continental  areas,  and  that  denudation  in  Archaean  time,  making 
sediment,  was  carried  on  by  the  ocean  along  its  margins  or  over  partly 
emerged  rocks,  and  by  streams  over  the  land,  as  it  is  now.  The  streams 
were  short  in  that  time  of  contracted  lands,  yet  well  supplied  with  water 

501. 


under  the  hot  climate.  The  thickness  of  the  rocks  indicates  that  the 
amount  of  deposition  and  rock-making  was  enormous.  The  waters  of  the 
small  streams  and  of  the  ocean  owed  much  of  their  efficiency  to  the  carbonic 
acid  they  contained,  this  gas  being  everywhere  in  excess.  Moreover,  under 
these  conditions,  the  formation  of  beds  of  iron  ore  along  the  shallow  margins 
of  the  sea  and  in  the  shallow  waters  of  the  land  would  have  been  necessarily 
one  of  the  great  features  of  the  later  part  of  Archaean  time ;  for  the  decom- 
posing iron-bearing  rocks  would  have  readily  yielded  their  iron  to  the  attack- 
ing carbonic  acid.  Moreover,  organic  deposits  of  silica  may  have  accompanied 
the  ore-beds  in  the  basin. 

A  thickness  of  30,000,  50,000,  and  80,000  feet  has  been  attributed  to  the  formations 
piled  up  in  one  series  or  region.  If  this  means  50,000  feet  or  more  in  a  single  geosyn- 
clinal  area  before  an  upturning,  the  estimate  is  to  be  doubted,  for  the  difficulties  of  correct 
measurement  of  flexed  rocks  are  great.  In  most  cases  the  facts  as  to  the  faults  and 
flexures  present  cannot  be  ascertained.  A  thickness  of  50,000  feet  of  uncrystalline 
sediments  in  a  geosyncline,  during  even  the  later  part  of  Archaean  time,  militates  against 
all  calculations  as  to  the  Archaean  rate  of  increase  downward  in  the  earth's  temperature  ; 
for  if  the  rate  were  1°  F.  for  10  feet  of  depth,  as  Thomson  has  calculated,  the  bottom  of 
such  a  geosyncline  would  have  had  a  temperature  of  5000°  F.  ;  or  if  1°  F.  for  25  feet,  it 
would  still  have  had  a  temperature  sufficient  nearly  for  the  fusion  of  basalt. 

ARCHAEAN  MOUNTAIN-MAKING. 

The  stratified  rocks  of  the  Archaean  are  almost  everywhere  upturned, 
and  generally  at  high  angles,  the  dip  usually  being  between  30°  and  90°. 
Only  portions  of  the  Huronian  are  nearly  horizontal.  Moreover,  as  repre- 
sented in  Fig.  501,  they  are  commonly  in  flexures,  from  a  few  yards  to  miles 
in  span.  Such  flexures,  whenever  they  occur,  are  evidence  that  great  upturn- 
ings  had  taken  place  of  the  Appalachian  kind.  The  crystallization  of  the 
rocks,  or  their  metamorphisrn,  was  an  accompanying  result.  The  rocks  of 
the  earliest  Paleozoic  often  lie  over  them  nearly  or  quite  horizontally,  as 
illustrated  in  the  accompanying  figure  (Fig.  502)  from  Logan,  representing 
a  section  from  the  northern  or  Canadian  side  of  the  Adirondacks.  Upon 
the  flexed  Archaean  rocks  lie  (2)  the  Potsdam  sandstone  of  the  Cambrian, 


452  HISTORICAL  GEOLOGY. 

and  (3,  4a,  46)  overlying  Lower  Silurian  strata.  Such  sections  of  Cambrian 
strata  over  the  upturned  Archaean  are  proof  that  the  mountain-making  in 
the  region  preceded  the  Cambrian  era.  It  is  probable  that  the  Adirondacks 
were  made  at  the  close  of  Archaean  time.  They  were,  from  the  first,  great 
mountains,  for  the  highest  of  the  summits,  Mount  Marcy,  now  stands  5000  feet 
above  the  Cambrian  seashore,  or  the  lowest  Cambrian  beds,  and  this  is  the 
height  remaining  after  long  ages  of  denudation.  For  the  original  height, 
8000  feet  above  the  Cambrian  tide-level  can  hardly  be  too  high  an  estimate. 

502. 


From  the  south  side  of  the  St.  Lawrence  iti  Canada,  between  Cascade  Point  and  St.  Louis  Rapids:  1,  gneiss ; 
2,  overlying  Potadam  sandstone;  3,  calciferous  sand-rock;  4a,  Trenton  limestone;  46,  Hudson  slates. 
Logan. 

The  fusion  of  beds  by  the  heat  in  the  lower  and  hotter  part  of  the  geo- 
syncline  would  have  made,  by  the  escape  of  the  liquid  rock  alone,  fissures, 
veins  of  igneous  rock  in  the  metamorphic  region,  and  also  inclosures  of  the 
broken  schists  of  the  upper  and  less  heated  part  of  the  mass  (page  448). 
Such  igneous  eruptions  are  of  the  same  age  as  the  metamorphism. 

How  many  epochs  of  upturning  occurred  in  the  course  of  Archaean  time 
is  unknown.  In  the  vicinity  of  lakes  Huron  and  Superior  (and  probably 
also  farther  east)  there  was  one  at  the  close  of  the  Laurentian  period. 

Over  the  Archaean  area  of  New  Jersey,  and  of  Orange  and  Putnam  counties  in  New 
York,  there  are  several  long  belts  of  Cambro- Silurian  rocks,  occupying  what  were 
originally  valleys  of  Archaean  time,  having  the  northeastward  trend  of  the  rocks.  They 
are  fossiliferous  in  New  Jersey,  and  partly  metamorphic  in  Putnam  County,  N.Y.,  north 
of  Peekskill.  They  once  spread  more  widely  over  the  Archaean  Highlands,  and,  perhaps, 
covered  the  whole  when  the  Coal-measures  were  finished,  as  considered  probable  by 
J.  P.  Lesley.  The  upturning  the  beds  have  undergone  took  place  in  spite  of  resistance 
to  fracture  or  compression  in  the  underlying  Archaean  rocks. 


SUBSEQUENT  ALTERATIONS  OP  ARCHAEAN  ROCKS. 

Archaean  rocks  have  in  many  places  undergone  changes  in  their  minerals. 
They  were  made  at  higher  temperatures,  under  greater  atmospheric  pressures, 
and  with  slower  rates  of  cooling,  than  ordinarily  obtain  now  at  the  earth's 
surface ;  and  these  changed  conditions,  and  especially  those  due  to  heat  from 
orographic  movements,  have  occasioned  alterations  in  some  constituents. 

Many  Archaean  rocks  that  are  now  hornblendic  were  originally  pyroxenic.  Since 
other  pyroxene  rocks  have  remained  unchanged,  some  circumstances  must  have  intervened 
to  commence  the  alteration  ;  and  it  may  be  that  it  was  a  heating  up  of  the  rocks  to  1000°  F., 
through  fracturings,  faultings,  and  crushings  attending  earth-movements  or  mountain- 
making.  Besides  the  above-mentioned  change,  chrysolite,  pyroxene,  hornblende,  and 


ARCHAEAN   TIME.  453 

other  minerals  have  been  converted  into  serpentine  ;  pyroxene  into  rensselaerite,  a  variety 
of  talc  ;  nephelite  into  gieseckite  ;  spinel  to  hydrotalcite.  Another  change  is  that  of  mag- 
netite to  hematite  ;  for  the  great  beds  of  hematite  sometimes  contain  octahedral  crystals 
now  consisting  of  hematite,  which,  when  formed,  were  octahedrons  of  magnetite. 

In  the  ore-beds  of  the  Huronian  the  layers  of  ore,  jasper,  or  other  materials  are  often 
much  broken  and  displaced.  The  grains  of  apatite  are  sometimes  more  abundant  along 
one  side  of  an  ore- bed  than  the  other,  or  have  some  reference  to  the  depressions  in  which 
the  ore  lies  (Browne,  1889).  The  dioryte  underlying  the  ore-bed  has  been  altered  in  many 
places  to  a  soft  clayey  material,  feeling  soapy,  resembling  the  fluccan  of  a  vein.  The 
underlying  rock  is  sometimes  that  of  a  dike,  but  whether  consisting  of  dioryte  or  diabase, 
it  is,  in  general,  probably,  as  Hunt  held,  a  rock  of  sedimentary  origin.  As  dioryte  and 
diabase  were  very  abundant  rocks,  sediments  made  from  them  would  have  then  been  com- 
mon. The  broken  and  otherwise  displaced  condition  of  the  ore-beds,  and  the  rearrange- 
ments of  the  ore  in  any  depressions  that  were  made,  would  have  been  a  consequence, 
under  the  results  of  wider  disturbance,  of  the  important  fact  that  in  the  change  of  the 
carbonate  to  hematite  or  magnetite,  there  is  a  reduction  in  the  former  of  one  third  in  bulk, 
and  in  that  of  limonite  to  the  same  ores,  a  reduction  of  one  half  or  more,  so  that  large 
spaces  would  have  been  opened,  favoring  large  displacements. 

The  subsequent  changes,  alluded  to  above,  probably  occurred  at  some  later  epoch  of 
regional  disturbance,  in  the  course  of  which  movement  was  produced  along  the  plane  of 
the  ore-bed.  Under  the  action  of  the  heat  from  friction  siliceous  and  other  solutions 
would  have  been  formed  anew  and  mineral  changes  have  taken  place. 


LIFE  OF  ARCHAEAN  TIME. 

Although  fossils,  according  to  present  knowledge,  are  absent  from  Archaean 
rocks,  or  are  of  questionable  character,  the  existence  during  the  later  part  of 
the  Archaean  of  aquatic  life  in  its  simplest  forms  is  rendered  almost  certain 
by  the  fact  that  the  temperature  of  the  waters  was  favorable  to  it,  and  by 
the  occurrence  among  the  stratified  rocks  of  beds  of  limestone ;  by  the 
abundance  in  many  limestones,  and  other  rocks,  of  graphite,  which  constitutes 
20  per  cent  of  some  layers  in  Canada ;  and  the  presence  in  the  Huronian  of 
carbonaceous  shales  or  slates  containing  40  per  cent  of  carbonaceous  mate- 
rials. The  life  belonged  to  that  division  of  Archaean  time  which  is  desig- 
nated, on  page  441,  the  Archaeozoic  aeon ;  and  the  Huronian  rocks  represent 
the  latter  part  of  this  aeon,  if  not  the  whole  of  it. 

PLANTS.  —  Graphite  —  crystallized  carbon  —  has  been  made  in  many 
later  rocks  by  the  alteration  of  coal-beds  ;  as  at  Worcester,  in  Massachusetts, 
in  Rhode  Island,  at  St.  John  in  New  Brunswick,  where  ferns  among  the  coal- 
plants  have  been  found  in  the  state  of  graphite,  in  Ayrshire,  Scotland,  and 
in  Bavaria.  Even  anthracite  has  been  observed  in  the  Archaean  rocks  of 
Arendal,  Norway.  Dawson  has  remarked  that  it  is  scarcely  an  exaggeration 
to  maintain  that  the  quantity  of  carbon,  in  the  form  of  graphite,  in  the 
Archaean  rocks  of  Canada  is  equal  to  that  in  similar  areas  of  the  Carbonifer- 
ous system.  It  is  reasonable  to  conclude,  therefore,  that  although  graphite 
may  also  be  produced  by  heat,  that  of  the  Archaean  was  largely  of  organic 
origin,  like  that  of  later  rocks.  The  metamorphism  of  shales  containing 
carbonaceous  materials  derived  from  vegetable,  if  not  also  animal,  tissues, 


454 


HISTORICAL   GEOLOGY. 


has  converted  the  carbon  into  graphite.  The  little-altered  Huronian  beds 
of  Wisconsin  still  contain  much  carbonaceous  material,  as  remarked  by 
Brooks  and  Chamberlin.  The  former  stated,  in  1876,  that  "  the  considerable 
amount  of  carbon  distributed  through  the  Huronian  indicated  much  organic 
life,  and  leads  to  the  hope  that"  those  imperfect  fucoidal  impressions 
reported  by  Julien,  in  the  second  volume  of  the  Report  on  the  Geology 
of  Michigan,  may  not  prove  delusive. 

The  earliest  plants  were,  beyond  doubt,  Algae,  water  species,  which  grow, 
like  most  plants,  by  taking  carbon  from  carbonic  acid ;  and  after  these,  the 
microscopic  Fungi  related  to  the  Bacteria  (Microbes),  which  take  their  car- 
bon for  growth  chiefly  from  organic  products ;  for  these  minute  plants  are 
essential  to  the  process  of  decay  of  organic  matters  and  also  to  the  produc- 
tion of  many  mineral  changes,  as  already  explained. 

The  chert  of  the  limestone  in  the  Penokee  belt  of  Huronian,  and  the 
jasper  associated  with  the  iron  ore  of  the  belt,  consist  partly  of  opal-silica, 
and  are  probably  from  silica-secreting  Algae  (Irving,  Van  Hise).  It  is  proba- 
ble that  plants  related  to  those  that  are  now  secreting  limestone  and  silica 
in  the  hot  waters  of  Yellowstone  Park,  below  temperatures  of  185°,  were 
already  doing  geological  work  in  the  making  of  limestones  and  silica  deposits 
during  the  later  Archaean.  One  species  of  supposed  " seaweed"  has  been 
named  Archceophyton  Newberrianum  by  N.  L.  Britton.  The  specimen,  from 
a  New  Jersey  crystalline  limestone,  consists  of  graphite  arranged  in  narrow 

parallel  stripes,  with  a  regularity  that  suggests 
organic  origin  ;  but  the  arrangement  may  well 
be  an  effect  of  the  pressure  attending  metamor- 
phism. 

ANIMALS.  —  With  regard  to   animal  life,  the 
supposed  fossil,  Eozoon  Canadense  of  Dawson,  is 
regarded  by  some  as  proof  of  the  existence  of  Rhiz- 
opods  (Foraminifers),  while  others  believe  it  to  be 
of  mineral  origin.     It  occurs  in  coral-like  masses 
which  are  sometimes  several  feet   in   diameter. 
Fig.  503  represents,  natural  size,  a  section  of  a 
specimen  from   Grenville,   Canada.      The   white 
bands  are  the  calcareous  layers  supposed  to  have 
been  secreted  by  a  layer  of  the  Rhizopods,  while 
the  dark  bands  correspond  in  position  to  the  layer 
of  Rhizopods,  and  are  made  up  of  mineral  mate- 
rial (serpentine  generally,  sometimes  pyroxene,  loganite,  etc.)  that,  after  the 
death  of  the  animals,  filled  the  cells.     Dilute  muriatic  acid  removes  the  lime- 
stone, and  opens  the  rest  to  examination. 

Localities  occur  in  the  third  or  Grenville  stratum  of  limestone  near  Grenville,  and  in 
the  Petite  Nation  Seignory  ;  also  in  Burgess  (where  the  calcareous  part  is  dolomite),  and 
at  the  Grand  Calumet,  in  a  limestone  whose  place  in  the  series  is  not  determined  ;  and  at 
Tudor  in  Hastings  County.  Eozoon  has  also  been  reported  from  Archaean  rocks  in  Bavaria 


503. 


Eozoon  Canadense.     Dawson. 


ARCHAEAN   TIME.  455 

and  named  E.  Bavaricwn;  also  from  Saxony,  Bohemia,  Hungary,  and  Pargas  in  Finland. 
The  specimens  of  Eozoon  were  first  supposed  to  be  Stromatopora  corals  (Logan's  Hep. 
Geol.  Can.,  1863,  page  49),  and  afterward  announced  as  Rhizopod  in  structure  by  Dawson  ; 
and  this  conclusion  has  since  been  sustained  by  W.  D.  Carpenter  and  others.  But  Eozoon 
specimens  have  also  been  examined  microscopically  by  good  observers,  among  them  King 
and  Rowney,  and  Mobius,  who  have  not  found  the  supposed  foraminiferal  characters. 
Quite  recently,  in  1891,  the  Tudor  specimens  were  examined  by  J.  W.  Gregory  with  this 
conclusion. 

Doubts  are  excited  also  by  the  close  resemblance  in  structure  to  specimens  that  are  of 
mineral  origin  ;  by  the  unequal  thickness  of  the  calcareous  layers  and  the  interstices  ;  and 
by  the  fact  that  serpentine  of  later  formations  has  afforded  similar  forms.  It  is  objected 
to  on  the  ground  that  this  mineral  is  often  minutely  interlaminated  with  fibrous  serpentine 
or  some  other  mineral,  showing  that  the  soft  amorphous  material,  as  it  solidified,  sometimes 
contracted  and  divided  into  thin  laminae,  leaving  spaces  between  to  receive  depositions  of 
any  kind  ;  in  the  Eozoon  the  infiltrating  material  was  usually  calcareous. 

Notwithstanding  the  imperfection  of  the  evidence,  the  existence  of 
Rhizopods  and  other  Protozoans  before  the  close  of  Archaean  time  is  gen- 
erally believed. 

The  calcium  phosphate  (apatite)  of  the  rocks,  which  is  common  in  some 
limestones,  is  also  supposed  to  be  of  organic  origin,  because  a  constituent  of 
organic  tissues  and  of  some  shells.  Its  abundance  also  in  the  iron  ores 
favors  this  view,  inasmuch  as  the  beds  of  ore  are  believed  to  be  marsh  pro- 
ductions. But  the  phosphate  is  distributed  in  grains  through  many  igneous 
and  other  crystalline  rocks,  and  the  evidence  may  only  prove  that  it  was 
present  in  solution  in  the  sea-waters  of  the  era. 

Above  the  grade  of  Protozoans,  the  type  which  is  most  likely  to  have 
existed  in  the  later  Archaean  is  that  of  Kotifers ;  for  there  is  good  reason  for 
believing,  as  stated  on  page  423,  that  from  this  group  passed  off  independent 
successional  lines  of  species  to  Worms,  Limuloids,  Crustaceans,  and  terres- 
trial Arthropods,  and  probably  also  to  Bryozoans,  Brachiopods,  and  perhaps 
other  tribes. 

ECONOMICAL  PRODUCTS. 

The  chief  economical  products  of  the  Archaean  terranes  are :  (1)  Gold, 
platinum,  diamond ;  (2)  Iron  ores  ;  (3)  Copper,  and  other  ores ;  (4)  Corun- 
dum or  emery ;  (5)  Graphite  ;  (6)  Architectural  materials,  especially  granite 
and  marble ;  (7)  Apatite  or  calcium  phosphate  for  fertilizing  purposes ;  (8) 
Feldspar  for  porcelain-making ;  (9)  Mica  for  the  doors  of  lanterns,  stoves, 
etc.,  and  various  other  uses ;  (10)  Zircon  and  monazite. 

The  iron  ores  are  among  the  most  valuable.  They  sometimes  contain  too 
much  titanium ;  and  occasionally  the  proportion  of  disseminated  grains  of 
apatite  affects  their  value.  This  mineral  may  be  distinguished  by  its  green- 
ish or  grayish  color  and  by  its  being  soft  enough  to  be  scratched  by  the  point 
of  a  knife-blade.  The  American  corundum  (A1203)  comes  mostly  from  North 
Carolina  and  Georgia.  A  mass  weighing  400  tons  was  formerly  obtained  in 
the  rocks  of  Chester  County,  Pennsylvania.  The  mineral  is  ground  up  and 
used  for  emery,  it  being  the  same  compound  as  emery,  but  in  a  purer  form. 


456  HISTORICAL   GEOLOGY. 

ARCK&AN  TIME   IN  OTHER  COUNTRIES. 

South  America  has  its  northern  region  of  Archaean  rocks  between  the 
equator  and  the  Orinoco,  which  would  probably  have  a  much  larger  super- 
ficial area  but  for  the  great  alluvial  and  Tertiary  area  of  the  Amazon  and 
other  rivers,  which  bound  it  for  150  miles  on  the  north  and  two  to  three 
times  this  width  on  the  west.  Archaean  ranges  also  occur  in  Brazil,  and  in 
different  parts  of  the  chains  of  the  Andes. 

In  the  continent  of  Europe  the  great  Archaean  region  is  the  Scandinavian, 
or  that  covering  the  most  of  Sweden,  Norway,  Lapland,  and  Finland.  The 
rocks  also  occupy  a  large  part  of  the  northern  half  of  Scotland  and  the  Outer 
Hebrides;  portions  of  western  Ireland,  at  Donegal  and  Gal  way,  and  of 
eastern,  in  Wicklow ;  at  St.  David's,  in  southwest  Wales ;  in  Anglesey,  off 
northwest  Wales ;  in  western  England,  in  the  Malvern  Hills ;  and  probably 
on  the  south  coast  of  Devon  and  Cornwall.  They  also  cover  areas  in 
Saxony,  Bavaria,  and  Bohemia;  in  Brittany,  Vosges,  and  the  Central 
Plateau  of  France. 

Crystalline  rocks  cover,  according  to  Blanford  (1879),  very  large  areas 
in  India.  "  More  than  half  of  Peninsular  India  is  taken  up  by  the  eastern 
gneissic  series."  They  extend,  with  scarcely  an  exception,  from  Cape 
Comorin  to  Colgong  on  the  Ganges,  1400  miles.  The  mean  breadth  of 
the  area  is  350  miles.  There  are  also  in  the  peninsula  a  northwestern 
area,  the  Arvali ;  and,  to  the  north  of  the  Vindhyan  plateau,  the  Bundel- 
khand  area.  But  it  is  not  certain  that  all  are  Archaean.  Besides  these,  there 
are  also  large  areas  of  semi-metamorphic  rocks.  The  main  Himalayan 
range  has  a  gneissic  or  granitic  axis,  but  the  limits  are  not  yet  laid  down ; 
and  in  the  Zanskar  range,  its  continuation  to  the  northwest,  there  is  a 
center  of  gneiss.  But  the  precise  relations  of  these  and  other  gneissic 
ridges  to  the  later  formations  has  not  been  ascertained. 

The  rocks  of  Scotland,  Norway,  Sweden,  and  other  Archaean  regions  are 
much  like  those  of  North  America  in  general  constitution,  and  in  the  range 
of  the  associated  minerals ;  and  in  Scandinavia  there  are  great  iron  ore  beds. 
The  massive  gneisses  of  the  Hebrides  and  northern  Scotland  were  called  the 
Lewisian  group  by  Murchison  (1858),  after  the  island  of  Lewis  in  the  Outer 
Hebrides.  Like  the  massive  and  the  thick-bedded  or  foliated  rocks,  which 
contain  the  iron  ore  beds  of  Scandinavia,  they  have  been  pronounced  on 
petrological  grounds  to  be  of  igneous  origin.  But,  for  reasons  already 
stated,  they  are  in  all  probability,  wherever  igneous,  metamorphic-igneous, 
or  the  result  of  fusion  attending  metamorphic  work.  The  foliation  of  the 
gneisses  and  other  rocks  represents,  in  general,  on  this  view,  true  bedding. 
The  iron  ore  beds  are  the  best  of  evidence  of  metamorphism.  The  crystal- 
line rocks  east  of  the  "  Great  glen "  in  Scotland  include  thin  schists  and 
quartzyte  with  gneiss,  and  have  been  called  the  Grampian  group  by 
H.  Hicks,  and  later  the  Dalradian  group  by  Geikie ;  it  is  supposed  to  be 
younger  than  the  Lewisian. 


ARCHAEAN  TIME.  457 

The  crystalline  rocks  of  St.  Davids,  in  Wales,  have  been  described  by 
Dr.  Hicks  as  of  three  periods :  (1)  the  Dimetian;  (2)  the  Arvonian;  and  (3) 
the  Pebidian.  Geikie  concluded,  after  an  examination  of  the  region,  that 
the  Dimetian  rocks  are  intrusive  granite ;  the  Arvonian,  "  quartz-porphyries  " 
connected  with  the  granite;  and  that  the  Pebidian  rocks  are  tufas  and 
diabases  belonging  to  the  lowest  Cambrian.  Dr.  Hicks's  view  that  the 
St.  Davids  rocks  are  partly  Archaean  is  favored  by  the  presence  in  the 
vicinity  of  fossiliferous  Cambrian.  It  is  now  adopted  by  Geikie. 

In  the  Torridon  district,  northwestern  Scotland,  a  thick  formation  of  red- 
dish and  brownish  sandstones,  wholly  uncrystalline  in  texture,  but  upturned 
to  a  high  angle,  lies  unconformably  both  upon  Archaean  gneisses  and  under- 
neath strata  of  Lower  or  Olenellus  Cambrian.  The  reported  thickness  is 
4000  to  8000  feet.  As  they  are  unfossiliferous,  it  remains  doubtful  whether 
the  Torridon  sandstone,  or  "  Torridonian  group,'7  should  be  referred  to  the 
later  Archaean,  or  to  the  earliest  Paleozoic.  Murchison  referred  them  to 
the  Cambrian. 


OBSERVATIONS   ON  THE  ARCH^AN. 

1.  Relations  of  the  North  American  Archaean  areas  to  the  continent.  —  The 

position  and  form  of  the  nucleal  Archaean  of  the  continent,  and  of  the  parallel 
ranges  on  either  side,  reaching  out  to  the  oceans,  prove  that  the  continent 
was  not  only  outlined,  but  also  marked  off  as  regards  its  grander  features  in 
Archaean  time.  This  is  established  also  by  the  great  thickness  of  meta- 
morphic  rocks ;  for  rocks  of  sedimentary  or  detrital  origin  are  not  made 
except  where  there  are  emerged,  or  nearly  emerged,  rocks  to  be  a  source  of 
material;  and  even  a  slight  submergence  makes  the  amount  of  decay,  and 
of  detritus  produced,  small.  Further,  the  existence  of  the  continents, 
emerged  or  at  shallow  depths,  is  evidence,  as  explained  on  page  380,  that 
the  oceanic  basin  also  was  denned  by  the  close  of  the  Archaean,  and  had 
nearly  its  present  mean  depth  of  12,000  feet. 

The  facts  thus  prove  that  the  scheme  of  progress,  even  to  minor  details, 
dates  from  the  beginning.  In  the  very  inception  of  the  continent,  not  only 
was  its  general  topography  foreshadowed,  but  its  main  mountain  chains 
appear  to  have  been  begun,  and  its  great  intermediate  basins  to  have  been 
defined.  The  evolution  of  the  grand  structure  lines  of  the  continent  was 
hence  early  commenced,  and  the  system  thus  initiated  was  the  system 
to  the  end.  Tracing  out  the  development  of  the  American  continent,  from 
these  Archaean  beginnings,  is  one  of  the  main  purposes  of  geological  history. 

2.  Correlation  of  Archaean  subdivisions.  — Names  of  Archaean  subdivisions 
are  multiplying  over  the  world  wherever  Archaean  rocks  are  studied.     The 
uncrystalline  terranes  are  safely  put  at  the  top  of  the  series  in  the  particular 
region  where  they  occur ;  but,  as  already  remarked,  they  may  be  the  equiva- 
lents of  crystalline  kinds  in  another  more  mountainous  region. 


458  HISTORICAL   GEOLOGY. 

With  the  more  crystalline  terranes  correlation  is  extremely  difficult. 
This  is  owing  to  the  absence  of  fossils ;  to  the  uncertain  value  of  the  cri- 
terion based  on  kinds  of  rocks ;  and  to  the  fact  that  no  subdivision  admits 
of  being  traced  to  any  great  distance,  except  the  kind  which  depends  on 
unconformity  in  bedding.  Since  this  kind  of  unconformity  is  a  consequence 
of  an  orographic  upturning,  and  mountain  ranges  have  usually  great  length, 
it  will  theoretically  exist  for  long  distances.  Subdivisions  based  on  other 
kinds  of  unconformity,  and  on  the  characters  of  the  rocks,  are  the  most 
common,  and  are  necessarily  of  only  local  value.  The  study  of  a  region 
with  reference  to  unconformity  in  bedding  involves  a  complete  investigation 
of  the  positions  of  the  planes  of  bedding,  or  foliation,  wherever  the  rocks 
are  exposed  to  view. 

The  beds  of  iron  ore  and  the  graphite-bearing  schists  of  Wisconsin  are 
proved  to  belong  to  the  later  part  of  Archaean  time  —  the  Huronian ;  and 
this  is  probably  true  for  the  associated  Archaean  beds  and  schists,  whether 
massive,  gneissic,  or  thin  schists,  and  hence  beds  of  iron  ore  are  a  great  help 
in  correlation.  The  beds  of  limestones  may  yet  be  found  to  give  aid  in  the 
same  direction. 

The  study  of  the  Archaean  rocks  has  difficulties,  but  not  so  great  as  are 
implied  in  the  term  "Basement  Complex,"  sometimes  used  for  the  more 
crystalline  kinds,  —  an  expression  that  sounds  like  a  wail  of  despair  on  the 
part  of  those  that  use  it. 

3.  Source  of  the  material  of  later  fragmental  rocks.  —  The  Archaean  rocks, 
and  rocks  made  from  them,  are  the  main  source  of  the  material  of  sub- 
sequent non-calcareous  fragmental  rocks.     Volcanic  eruptions  have  added 
a  little  to  the  supply ;  chemical  depositions  also  a  little ;  and  the  siliceous 
secretions  of  the  lowest  orders  of  plants  and  animals  have  contributed  silica 
to  some  extent;   but  all  these  sources  are  small  compared  with  those  of 
the  Archaean  terranes.     Even  the  limestones  have  derived  much  of  their 
material  from  the  same  source,  through  the  dissolving  waters.     The  areas 
were  well  distributed  over  the  continent  for  supplying,  through  the  help  of 
the  ocean,  mud,  sand,  and  gravel  for  the  deposits  that  were  in  progress  as 
the  next  era  opened — better  even  than  is  now  apparent,  since  many  once 
exposed  are  now  covered,  especially  along  the  sea-borders,  where  the  later 
rocks  have  often  great  thickness.     And  their  contributions  have  continued 
ever  since  to  be  used  in  rock-making,  both  directly  and  through  the  strata 
which  had  been  made  from  them. 

4.  The  first  of  living  species.  —  Science  has  no  explanation  of  the  origin  of 
Life.     The   living  organism,   instead   of  being   a   product   of  physical   or 
chemical    forces,    controls    these    forces  for    its    higher    forms,    functions, 
and   purposes.     Its   introduction  was   the   grandest  event   in  the  world's 
early  history. 

It  is  probable  that  the  first  species  were  of  the  simplest  kinds ;  that  the 
animals  were  devoid  of  special  organs  of  sense,  and  of  motion,  excepting 


AECH^AN    TIME.  459 

short,  hair-like  processes ;  and  of  nutrition,  beyond  at  the  best  a  cavity  for 
digestion.  But  the  principles  inaugurated  were  those  fundamental  to  all 
life.  Some  of  them  are  as  follows  :  — 

1.  The   subordination   of  chemical  and  physical  forces  to  the  control  of 
living  conditions. 

2.  Germ-development,  by  which,  from  a  germ-cell,  a  structure  of  various 
functions  becomes  evolved,  and  is  carried  to  an  adult  or  germ-producing 
stage,  when  new  germs  are  produced  for  another  cycle  of  development. 

3.  Death  of  the  adult,  a  fundamental  stage  in  the  cycle,  —  the  institution 
of  life  involving  the  introduction  of  death. 

4.  In  the  case  of  animal  life,  dependence  on  living  food  for  growth  —  a 
principle  that  pervades  the  animal  kingdom  from  its  lowest  species  to  Man. 

5.  As  a  consequence  of   growth  and  germ-development  in  animals,  the 
initiation  of  two  diverse  moral  forces,  which  later  became  a  power  in  the 
world:   (a)  the  affiliating  influence,  arising  out  of  the  relation  of  parent 
to   progeny;    (6)  the    antagonistic,   self-asserting    influence,   arising    from 
the  necessity  of  food.     Each  element  had  reinforcements  from  other  appe- 
tites or  conditions  in  animal  life. 


II.    PALEOZOIC   TIME. 

SUBDIVISIONS. 
The  higher  subdivisions  of  Paleozoic  time  are  as  follows :  — 

1.  Eopaleozoic  Section. 
I.   CAMBRIAN  ERA. 

II.   LOWER  SILURIAN  ERA. 

2.  Neopaleozoic  Section. 
I.   UPPER  SILURIAN  ERA. 

II.   DEVONIAN  ERA. 
III.    CARBONIC  ERA. 

Paleozoic  time  is  naturally  divided  into  two  sections  at  the  break 
between  the  Lower  and  Upper  Silurian.  This  boundary  line  is  marked  in 
the  history  by  an  epoch  of  mountain-making  in  eastern  North  America  and 
western  Europe,  and  by  a  somewhat  abrupt  transition  in  the  animal  life  of 
the  seas.  These  sections  are  here  named  by  using  prefixes  to  the  term 
paleozoic  derived  from  the  Greek  T)W?,  dawn,  and  veos,  new. 

The  first  of  these  sections,  the  Eopaleozoic,  was  characterized  by  the  fact 
of  almost  universal  seas  over  the  continental  area,  and  of  universal  marine 
life,  and  also  by  the  more  specific  Paleozoic  fact,  that  marine  Invertebrates, 
or  the  species  of  the  inferior  division  of  the  Animal  Kingdom,  were  dis- 
played under  nearly  all  their  grander  types  before  the  close  of  this  section 
of  Paleozoic  time ;  and  also  that  the  highest  division  of  the  Animal  King- 
dom, Vertebrates,  was  represented  by  species  of  the  inferior  type  of  Fishes. 

The  second  of  the  sections,  the  Neopaleozoic,  was  characterized  by  the 
gradually  increasing  extent  of v  dry  land  over  the  continental  area,  and  the 
covering  of  the  emerged  surface  with  land  plants,  and  finally  with  great 
forests ;  and  also  by  the  multiplication  of  terrestrial  species  of  animal  life 
among  Invertebrates,  and  finally  among  Vertebrates.  With  the  progress  of 
the  era,  Cryptogams,  plants  of  the  lower  division  of  the  Vegetable  Kingdom, 
reached  their  culmination  in  grade,  size,  and  diversity  of  kinds;  and  the 
superior  division  of  the  Vegetable  Kingdom,  Phaenogams,  was  represented 
by  species  of  the  inferior  type  of  Gymnosperms. 

The  Eopaleozoic  section  was,  biologically,  following  Agassiz's  method  of 
designation,  the  time  of  the  E-eign  of  the  Invertebrates,  and  prominently  of 
Trilobites ;  the  Neopaleozoic,  in  its  Upper  Silurian  and  Devonian  eras,  the 
time  of  the  Eeign  of  Fishes,,  and  in  the  Carbonic  era,  that  of  the  Keign  of 
Amphibians. 

The  first  real  progress  in  correlating  the  Paleozoic  rocks  of  North  America  and 
Europe  was  made  through  the  labors  of  the  geologists  of  the  survey  of  the  State  of  New 
York,  and  those  of  Murchison,  Sedgwick,  De  Verneuil,  and  others  abroad.  But,  in  this 

460 


PALEOZOIC   TIME.  461 

work,  American  geology  owes  much  to  De  Verneuil  for  liis  "note"  of  64  pages  in  the 
Bulletin  of  the  Societe  Geologique  de  France,  iv.,  1847,  "  On  the  Parallelism  of  the  Paleo- 
zoic Formations  of  North  America  with  those  of  Europe,"  which  is  followed  by  a  list  of 
the  species  of  fossils  common  to  the  two  continents,  and  of  the  rocks  in  which  they  occur, 
with  critical  remarks  respecting  each  species;  and  to  the  paper  of  D.  Sharpe,  "  On  the 
Fossil  Mollusks  from  the  Paleozoic  Formations  of  the  United  States,"  contained  in  the 
collections  of  C.  Lyell,  Q.  J.  G.  Soc.,  1848. 


AREAS  OF  GEOLOGICAL  PROGRESS. 

Archaean  geography,  as  has  been  explained,  largely  determined  the  areas 
of  later  geological  progress,  and  the  character  of  continental  geography 
through  all  the  ages.  The  prominent  points  in  North  American  geography, 
besides  the  fundamental  one  of  the  Archaean  nucleus,  are  the  denning  of  the 
two  great  Archaean  chains  of  islands  or  island  ridges,  the  Appalachian  pro- 
taxis  on  the  east,  the  Rocky  Mountain  protaxis  on  the  west  (page  24).  By 
this  means  a  vast  Interior  Continental  Sea  was  divided  off  from  an  Atlantic 
border  region  on  the  east,  and  a  Pacific  border  region  on  the  west,  the  former 
(reckoning  to  the  100-f athom  line,  or  the  steep  border  of  the  Atlantic  depres- 
sion) averaging  300  miles  in  width,  but  becoming  three  times  this  in  the 
latitude  of  Newfoundland ;  the  latter,  1000  miles  in  mean  width. 

Besides  this,  the  shorter  Archaean  ranges  of  the  Atlantic  border  region 
to  the  north  (see  the  map)  divide  the  surface  into  a  parallel  series  of  broad 
channels  or  troughs,  all  of  which  open  northward  into  the  St.  Lawrence 
valley  region. 

1.  The  Champlain  and  St.  Lawrence  channel :  between  the  northern  part 
of  the  protaxis  and  the  Archaean  lands ;  on  the  west  stand  the  Adirondacks, 
and  on  the  north  the  Canada  Archaean. 

2.  The    Connecticut   valley   channel,   or  trough,   along    the   CoDnecticut 
valley,  and  reaching  Long  Island  Sound  at  New  Haven  Bay,  Conn. 

3.  The  Maine-Worcester  channel :  covering  Maine  and  western  New  Bruns- 
wick and  extending  down  to  Worcester,  Mass. ;  apparently  fading  out  south- 
ward.    The  fiord  of  the  Thames  Eiver,  from  Norwich  to  New  London,  Conn., 
lies  in  its  course. 

4.  The  Acadian  channel :  extending  from  St.  Lawrence  Bay  and  western 
Newfoundland  over  eastern  New  Brunswick  and  much  of  Nova  Scotia,  with 
the  Bay  of  Fundy  between,  as  the  remains  of  this  part  of  the  depression ; 
thence  southeastward  along  and  off  the  coast  regions  of  Maine  to  Massachu- 
setts Bay,  and  over  eastern  Massachusetts  to  Narragansett  Bay,  on  the 
Atlantic  border. 

5.  The  Exploits  River  channel  of  central  Newfoundland,  and  two  others 
to  the  eastward. 

The  importance  of  these  channels,  or  troughs,  becomes  strongly  pronounced 
in  the  course  of  Paleozoic  history. 

Over  the  Pacific  border  region  the  areas  are  less  plainly  indicated  than 


462  HISTORICAL   GEOLOGY. 

over  the  Atlantic,  because  the  western  half  of  the  continent  is  so  generally 
covered  with  Mesozoic  and  Cenozoic  rocks. 

Paleozoic  rocks  are  the  prevailing  kinds  exposed  to  view  over  the  eastern 
half  of  the  North  American  continent,  excepting  along  the  borders  of  the  Mex- 
ican Gulf  and  of  the  Atlantic  south  of  New  York.  The  older  formations  of 
the  series,  as  the  map  on  page  412  illustrates,  lie  near  the  Archaean  area,  not 
far  north  or  south  of  the  northern  boundary  of  the  United  States  ;  and  the 
newer  formations  outcrop  in  succession  southward,  the  Carboniferous  covering 
much  of  Pennsylvania  and  other  States. 

Fig.  504  is  an  ideal  section  of  the  Paleozoic  rocks  of  New  York,  along  a 
line  running  southwestward  from  the  Archaean  across  the  state  to  the  coal 

504. 


Carbonic.  Devonian.  Upper  Silurian.  Lower  Sil.   Camb. 

region  of  Pennsylvania.  It  shows  the  relative  positions  of  the  successive 
strata,  — bringing  out  to  view  the  fact  that  the  areas  over  the  region  are  only 
the  outcrops  of  the  successive  formations.  This  is  all  the  section  is  intended 
to  teach ;  for  the  uniformity  of  dip  and  its  amount  are  very  much  exagger- 
ated, and  the  relative  thickness  is  disregarded.  Along  the  Appalachians  the 
older  Paleozoic  rocks  occur  in  long  belts  parallel  with  the  axis  of  the  range, 
because  of  the  great  upturning  of  the  formations  that  took  place  at  the  close 
of  the  Carboniferous,  when  the  mountains  were  made. 

EOPALEOZOIC   SECTION. 
CAMBRIAN  ERA. 

STN.  —  Cambrian,  Sedgwick,  Eep.  Brit.  Assoc.,  1835.  Cambrian  (Murchison's  Lower 
and  Upper  Silurian  being  made  higher  divisions  of  the  Paleozoic  series),  Sedgwick, 
Q.  J.  G.  Soc.,  1846,  page  130.  Cambrian  (Murchison's  Lower  Silurian  being  included 
under  it),  Sedgwick,  Q.  J.  G.  Soc.,  1852,  page  147.  Lower  part  of  Lower  Silurian,  Mur- 
chison,  Q.  J.  G.  Soc.,  1852,  page  173;  D'Orbigny,  GeoL,  1851. 

Cambrian,  Lyell,  Elements  GeoL,  2d  ed.,  1841  ;  5th  ed.,  1855;  Geikie,  Text-book  of 
GeoL,  1879,  1885;  Lapparent,  Tr.  de  GeoL,  1883;  Seeley  and  Etheridge,  Man.  GeoL, 
1885  ;  Prestwich,  GeoL,  1886 ;  E.  Kayser,  Lehrb.  geol.  Form.,  1891. 

Primordial  or  lower  division  of  the  Silurian  System,  Stage  C,  Barrande,  Syst.  Silurien 
de  Boheme,  1852.  Cambrian  or  Primordial,  a  subdivision  of  the  Lower  Silurian,  this 
GeoL,  1874,  1880;  C.  Vogt,  GeoL,  2d  ed.,  1866;  Credner,  GeoL,  6th  ed.,  1887. 


PALEOZOIC   TIME  —  CAMBRIAN.  463 

Potsdam  Sandstone,  New  York  Geol.  Survey,  1842.  Primal  Sandstone,  H.  D.  and 
W.  B.  Kogers.  Upper  Taconic,  fossiliferous  slates  of  Georgia,  etc.,  E.  Emmons,  1844, 
1846  (not  in  the  Taconic  System  of  1842) . 

History  of  the  terms  Cambrian  and  Silurian. — The  terms  Cambrian  and 
Silurian  recognize  the  united  labors  of  Murchison  and  Sedgwick  in  the  first 
careful  study,  in  Great  Britain,  of  the  older  fossiliferous  rocks  of  Paleozoic 
time.  The  two  eminent  English  geologists  worked  together  in  some  of  their 
earlier  investigations.  The  memoirs  of  that  period,  "Communications  on 
Arran  and  the  north  of  Scotland,  including  Caithness  (1828)  and  the  Moray 
Firth,  others  on  Gosau  and  the  eastern  Alps  (1829-1831)  ;  and  still  later,  in 
1837,  a  great  memoir  on  the  Paleozoic  strata  of  Devonshire  and  Cornwall, 
and  another  on  the  coeval  rocks  of  Belgium  and  north  Germany,  show  the 
labors  of  these  intimate  friends  combined  in  the  happiest  way  —  the  broad 
generalizations  in  which  the  Cambridge  professor  delighted,  well  supported 
by  the  indefatigable  industry  of  his  zealous  companion." l  In  1831,  they  were 
both  at  work  "  without  concert "  on  the  borders  of  Wales,  — Murchison  chiefly 
on  the  English  side  and  in  southern  Wales,  and  Sedgwick  beyond  the  bound- 
ary in  north  Wales.  Sedgwick  had  earlier  investigated  somewhat  similar 
rocks  in  the  Cumbrian  Mountains.  By  1834,  Murchison  had  laid  down  his 
grand  divisions  of  Ludlow,  Wenlock,  Caradoc,  and  Llandeilo,  and  had  referred 
the  first  two  of  them,  on  the  ground  of  the  wide  difference  in  fossils,  to  the 
Upper  Silurian,  and  the  latter  two  to  the  Lower  Silurian.  In  1835,  the  terms 
Cambrian  and  Silurian  appear  together  in  a  combined  paper  presented  by 
the  two  authors  to  the  first  meeting  of  the  British  Association.  Silurian 
had  been  announced  by  Murchison  nearly  two  months  before  in  the  July 
number  of  the  Philosophical  Magazine.  In  1838,  each  put  forth  more  fully 
his  results  :  Sedgwick,  in  a  paper  read  before  the  Geological  Society,  giving 
the  distribution  and  character  of  the  rocks,  with  but  little  notice  of  the  char- 
acteristic fossils ;  but  Murchison,  before  the  close  of  the  year,  in  a  quarto 
volume  of  800  pages  copiously  illustrated  with  figures  of  fossils  and  geologi- 
cal sections,  entitled  the  "Silurian  System."  Murchison's  work  and  his 
names  of  subdivisions  came  into  immediate  use  in  all  countries,  and  were 
recognized  in  all  geological  treatises. 

Gradually  it  came  to  light  that  the  Lower  Silurian  of  Murchison  com- 
prised rocks  and  fossils  of  the  age  of  the  Upper  Cambrian;  and  also  that 
the  fossils  from  beds  of  still  lower  level  differ  little  in  general  type  from 
those  of  the  Lower  Silurian.  Thus  geologists,  with  Murchison's  book  in 
hand,  were  led  to  use  the  term  Lower  Silurian  for  the  fossiliferous  Cambrian. 
No  fall  account  of  Sedgwick's  Cambrian  fossils  was  published  before  1852 
to  1855,  and  not  even  lists  of  species  before  1843. 

In  1846  Sedgwick  made  his  first  protest  against  the  absorption  of  the 
Cambrian  by  the  Lower  Silurian  of  Murchison  ;  and  in  1852  the  controversy, 
thus  begun,  ended  in  his  claiming  the  whole  of  the  Lower  Silurian  as  Upper 

1  Professor  John  Phillips,  Nature,  Feb.  6,  1873. 


464  HISTORICAL   GEOLOGY. 

Cambrian,  and  in  Murchison's  expressing  his  satisfaction  that  geologists  and 
paleontologists  everywhere,  in  America  as  well  as  in  Europe,  had  already 
adopted,  through  the  use  of  his  publications,  his  subdivisions  and  terms. 
Later,  after  collections  of  Cambrian  or  Primordial  fossils  had  been  much 
enlarged  through  new  discoveries,  the  names  Cambrian  and  Lower  Silurian 
became  accepted  for  successive  divisions  of  the  Paleozoic  series. 

The  term  Cambrian  is  derived  from  the  old  name  of  Wales,  and  Silurian 
from  the  tribe  of  Silures,  which  inhabited  southeastern  Wales  and  Mon- 
mouth,  England. 

For  a  more  detailed  history  of  the  terms  Cambrian  and  Silurian,  see  the  Am.  Jour. 
Sc.,  xxxix.,  1890  ;  also  Murchison's  Life  by  A.  Geikie,  1875. 

AMERICAN. 

SUBDIVISIONS. 

3.  POTSDAM  period,  Reports  New  York  Geologists,  1838,  1842.  UPPEB 
CAMBRIAN,  Walcott.  LATER  CAMBRIAN. 

2.  ACADIAN  period,  Dawson,  Acad.  Geol.,  1868.  MIDDLE  CAMBRIAN,  or 
Paradoxides  zone,  Walcott,  1887.  Named  Acadian  from  the  locality  at 
St.  John,  New  Brunswick. 

1.  GEORGIAN  period,  1886;  LOWER  CAMBRIAN  or  Olenellus  zone,  1887, 
C.  D.  Walcott,  Bull  U.  S.  G.  S.  Keweenawian,  T.  B.  Brooks,  Am.  Jour.  Sc., 
xi.  206,  1876;  Keweenawan,  Chamberlin,  1883;  Irving,  1887;  Keweenian, 
A.  Winchell,  1886. 

ROCKS  — KINDS  AND  DISTRIBUTION. 

General  Distribution.  —  The  Cambrian  rocks  rest  upon  the  upturned 
Archaean  terranes,  and  usually  outcrop  along  the  borders  of  Archaean  areas. 
In  eastern  North  America  they  occur,  adjoining  the  Archaean  nucleus,  on 
one  or  both  sides  of  the  Appalachian  protaxis,  from  Canada  to  Alabama,  and 
occupy  parts  of  some,  if  not  all,  of  the  channels  or  troughs  of  Archaean  con- 
fines from  the  Adirondacks  to  the  eastern  limits  of  Newfoundland.  They 
are  in  part  beach-made  and  wind-made  sandstones,  or  offshore  limestones,  or 
slates  or  schists  that  originally  were  mud  beds ;  and  the  layers  often  bear 
ripple-marks,  shrinkage  cracks,  worm-burrows,  and,  in  some  places,  tracks 
of  animals. 

Similar  relations  to  the  Archaean  exist  at  various  localities  of  the  Lower 
Cambrian  over  the  continent,  to  the  far  west.  They,  are  found  about  Ar- 
chaean outcrops  in  Texas  and  South  Dakota,  and  along  the  Eocky  Mountain 
protaxis  in  British  America  and  the  United  States,  and  also  farther  west  in 
Nevada ;  and  occasionally  they  are  reached,  over  the  Pacific  slope,  by  the 
canon  cuts  of  rivers  thousands  of  feet  in  depth,  as  in  that  of  the  Colorado. 

The  accompanying  sketch  of  a  portion  of  the  "  Pictured  Rocks "  in  the 
Lake  Superior  sandstone,  near  Carp  River,  Michigan,  illustrates  the  usual 


PALEOZOIC   TIME  —  CAMBRIAN. 


465 


unconformability  between  the  Cambrian  beds  and  the  Archaean,  exempli- 
fying the  fact  that  the  upturned  Archaean  made  the  bottom  of  the  Cambrian 
seas,  over  which  the  great  sandflats,  or  other  sand  depositions,  were  made. 
The  view  also  shows  that  the  Cambrian  beds  had  been  slightly  tilted 
since  their  formation. 


505. 


Unconformability  at  Carp  River,  Chippewa  County,  Mich.    J.  D.  Whitney. 

The  fossiliferous  beds  in  eastern  Newfoundland  of  the  Lower  Cambrian 
consist  of  shales,  sandstones,  and  conglomerates,  of  shallow  water  origin, 
and  are  hence  evidence  that  the  Cambrian  continent  stretched  eastward  as 
far  as  the  existing  continent.  It  probably  had  the  Pacific  for  its  western 
border ;  for  through  the  investigations,  principally  of  C.  D.  Walcott,  out- 
crops have  been  discovered  over  the  Rocky  Mountain  border  to  points  within 
500  to  400  miles  of  the  Pacific  coast ;  and  further  investigation  is  likely  to 
carry  the  discoveries  as  far  west  as  Archaean  ridges  exist. 

In  the  Lower  Cambrian  region  of  South  Mountain,  southeastern  Penn- 
sylvania, west  of  the  Susquehanna  and  in  the  adjoining  part  of  Maryland, 
the  Cambrian  series  overlies  unconformably,  according  to  the  study  of  the 
rocks,  and  the  region,  by  Gr.  H.  Williams  and  C.  D.  Walcott,  beds  and  dikes 
of  various  igneous  rocks,  as  basalts  and  rhyolytes,  and  also  tufaceous  accu- 
mulations of  the  same  origin  (1892,  1894). 

The  Keweenaw  Group,  probably  Lower  Cambrian.  —  No  allusion  is  made 
above  to  the  Keweenaw  group,  because  it  was  a  local  formation.  It  occupies 
a  belt  of  country  on  the  south  side  of  Lake  Superior,  covering  Keweenaw 
Point,  where  it  is  best  displayed,  and  extending  from  thence  westward.  It 
is  called  the  copper-bearing  sandstone  formation  from  its  characteristic 
rocks  and  its  noted  copper  mines.  But  the  feature  of  greatest  geological 
DANA'S  MANUAL  —  30 


466  HISTORICAL  GEOLOGY. 

significance  is  the  igneous  origin  of  a  large  part  of  the  formation.  Sheets 
of  basic  igneous  rocks,  partly  amygdaloids,  with  others  of  felsyte,  porphyry, 
and  granite,  are  interstratified  with  the  sandstones  and  conglomerates,  and 
the  latter  are  largely  made  of  water-worn  detritus  of  like  igneous  origin. 
The  beds  are  wholly  unmetamorphic  to  the  bottom,  and  hence  there  is 
nothing  in  them  to  prove  that  the  formation  is  Archaean.  At  the  same 
time,  no  fossils  have  been  found  to  prove  it  Cambrian.  Still,  inasmuch 
as  it  overlies  unconformably  the  upturned  Huronian,  it  must  be  of  sub- 
sequent origin  ;  and  as  no  Cambrian  rocks  occur  in  Wisconsin  older  than  the 
Middle  Cambrian,  it  is  reasonable  to  suppose  that  it  may  represent  the  Lower 
Cambrian.  The  absence  of  fossils  may  be  owing  to  the  region's  having  been 
under  fresh  water,  or  to  the  igneous  action.  The  copper  veins  of  the  Kewee- 
naw  region  have  been  discussed  on  page  341,  under  the  head  of  Veins. 

It  is  important  to  note,  however,  that  the  igneous  effusions  which  accom- 
panied the  deposition  of  beds  below  the  Lower  Cambrian  in  southeastern 
Pennsylvania  and  the  adjoining  borders  of  Maryland,  are  similar,  as  Williams 
remarks,  to  the  rocks  of  the  Keweenaw  series  not  only  in  kinds,  but  also  in 
the  presence  of  much  metallic  copper.  Walcott  and  Williams  conclude  that 
the  eruptions  in  the  two  areas  were  simultaneous  and  alike  pre-Cambrian. 

Bearing  of  the  facts  connected  with  the  distribution  of  the  Cambrian  on 
questions  as  to  the  upturning  preceding  the  era.  —  From  the  facts  observed 
in  connection  with  the  distribution  of  the  Cambrian  over  the  Archaean  of 
northern  New  York  and  Canada  and  in  Archaean  troughs  to  the  eastward,  it 
appears  to  follow  that  the  mountain  ranges  in  eastern  America  that  were 
made  at  the  close  of  the  Archaean,  and  that  stand  as  the  time-boundary 
between  the  Archaean  and  Paleozoic,  include  the  Adirondacks,  the  Appa- 
lachian protaxis,  and  other  more  eastern  ridges ;  and  that  these  mountains 
consist,  in  part,  if  not  largely,  of  rocks  that  were  laid  down  as  sediments 
during  the  long  Huronian  era,  though  now  crystalline  or  metamorphic  and 
in  part  massive  crystalline.  The  disturbances  closing  Archaean  time  do  not 
appear  to  have  extended  their  effects  alike  over  the  whole  surface  of  the 
continent,  but  to  have  produced  their  chief  uplifts  along  the  mountain 
borders ;  that  is,  in  those  regions  in  which  the  most  extensive  mountain- 
making  occurred  in  later  time.  Over  the  Continental  Interior,  the  Huronian 
sediments  were  thinner,  the  upturnings  at  the  epoch  of  disturbance  less 
prominent,  and  the  metamorphism  feebler,  where  not  wholly  wanting. 

Walcott  has  classified  the  areas  of  geographic  distribution  of  the  surface  outcrops 
of  the  Cambrian  strata  as  follows  (Bull.  81,  U.  S.  G.  £.,  page  358)  :  — 

A.  Atlantic  or  Eastern  Border  Province  :  a,  Eastern  or  Nova  Scotia  Basin;  6,  South- 
eastern Newfoundland,  Eastern  New  Brunswick  and  Massachusetts  Basin ;   c,  Interior 
Deposits  of  Gaspe,  Quebec,  Maine,  New  Hampshire,  Vermont,  Massachusetts. 

B.  Appalachian  or  Interior  Eastern  Border  Province. 

C.  Rocky  Mountain  or  Western  Border  Province. 

D.  Interior  Continental  Province:    D1,  Central  Interior,  or  Upper  Mississippi  and 
Missouri ;  D 2,  Eastern  Interior,  or  Adirondack  of  New  York  and  Canada  ;  D 3,  Western 
Interior,  or  Dakota,  Wyoming,  etc. ;  D  4,  Southwestern  Interior,  or  Arizona  and  Texas. 


PALEOZOIC   TIME  —  CAMBRIAN.  467 

Eastern  Border  Region.  — In  southeastern  Newfoundland,  on  Manuel's  Brook,  occur 
shales,  with  some  limestone,  overlying  a  conglomerate,  in  all  400' ;  above  occur  beds  with 
the  Paradoxides  fauna,  and  below  it,  within  40'  of  the  conglomerate,  species  of  the 
Olenellus  fauna;  the  former  occurs  also  at  Topsail  Head  and  on  Conception  Bay 
(Walcott).  In  the  Acadian  trough,  Lower  Cambrian  fossils  are  reported  from  the  north 
side  of  the  Straits  of  Belle  Isle,  at  L'Anso  au  Loup,  and  on  the  opposite  coast  at  Canada 
Bay,  Labrador  ;  Middle  Cambrian,  as  gray  and  black  shales,  in  New  Brunswick,  near 
St.  John,  with  also  Upper  Cambrian  beds  ;  in  eastern  Massachusetts  ;  the  Lower  Cambrian 
at  Nahant,  and  in  Bristol  County,  near  northeastern  Rhode  Island,  and  the  Middle  Cam- 
brian at  Braintree,  where  a  thick  conglomerate,  much  flexed,  underlies  500'  to  10007  of 
slate. 

Continental  Interior  Region  (west  of  the  Appalachian  protaxis).  — Along  the  Green 
Mountain  region  in  Vermont  and  Massachusetts,  among  the  rocks  of  the  Taconic  series,  a 
great  quartzyte  formation,  having  intercalations  of  hydromica  and  mica  schist  and  occa- 
sionally ottrelite  schist,  has  been  shown  by  fossils  to  be  in  part  or  wholly  Lower  Cam- 
brian. The  Sillery  sandstone  of  Logan,  in  Canada,  is  part  of  the  quartzyte  formation. 
The  limestone  (white  marble),  adjoining  the  quartzyte  on  the  west,  has  afforded  Lower 
Cambrian  fossils  to  the  eastward  and  northward  of  Rutland.  The  continuation  of  this 
limestone  belt,  in  Massachusetts,  called  the  Stockbridge  limestone,  is  too  highly  crystalline 
for  fossils ;  it  may  be  in  part  Cambrian.  West  of  the  Taconic  limestones  in  central  Ver- 
mont, Lower  Cambrian  is  represented  by  the  red  sandrock  of  the  region.  In  north- 
eastern Vermont,  at  Georgia,  magnesian  limestone,  1000'  thick,  is  overlaid  by  a  great 
thickness  of  shales  ;  at  Highgate  the  same  limestone  is  1200'  thick. 

The  reddish,  mottled  "  Winooski  limestone,"  of  the  Georgia  Cambrian,  is  worked  for 
marble  at  Swanton. 

West  of  the  New  England  line,  Lower  Cambrian  occurs  in  Washington  County,  New 
York,  near  Bald  Mountain  and  elsewhere  ;  in  the  western  part  of  Rensselaer  County,  at 
Troy,  in  shales  and  limestone  and  at  Schodack  Landing ;  at  several  places  in  Dutchess 
County,  at  Stissing  Mountain,  where  Middle  Cambrian  fossils  also  occur. 

West  of  Lake  Champlain,  about  the  Adirondacks,  the  Potsdam  sandstone,  chiefly 
Upper  Cambrian,  has  a  thickness  in  St.  Lawrence  County  of  60'  to  70' ;  in  St.  Lawrence 
valley,  of  300'  to  600'  or  more ;  in  Warren  and  Essex  counties,  of  about  100'.  But  in 
Dresden,  Washington  County,  it  occupies  a  depression  at  a  height  of  912'  above  Lake 
Champlain.  A  lower  portion  of  the  sandstone,  according  to  Walcott,  is  Middle  Cam- 
brian. 

In  New  Jersey,  Sussex  County,  at  Hardistonville,  Olenellus  occurs  in  sandstone,  and 
other  Cambrian  fossils  in  the  Magnesian  limestone  near  Franklin  Furnace,  and  north  of 
Franklin  Furnace  Pond  (C.  E.  Beecher).  Foerste  has  found  the  Olenellus  fauna  in  the 
same  region,  and  also  south  of  Sparta  Junction,  northeast  of  Long  Pond  ;  and  he  has 
traced  it  south  west  ward  into  eastern  Pennsylvania  ;  he  shows  that  the  quartzyte  of  the 
region,  instead  of  being  Potsdam  Upper  Cambrian,  is  mostly  Lower  Cambrian  as  in  Ver- 
mont (1893). 

The  Lower  Cambrian  has  been  traced  by  Walcott  from  New  Jersey  southwestward 
across  Pennsylvania.  In  southeastern  Pennsylvania,  west  of  the  Susquehanna,  over 
parts  of  York,  Adams,  Franklin,  and  Cumberland  counties,  about  South  Mountain,  east 
of  the  river  in  Lancaster  County,  and  in  adjoining  parts  of  Maryland,  the  Lower  Cam- 
brian includes  a  great  thickness  of  quartzyte  with  overlying  shales  or  slates  and  limestone  ; 
and  besides  these  rocks  there  are,  in  South  Mountain,  large  flows  of  basaltic  and  rhyolytic 
rocks.  In  Virginia,  fossiliferous  shales  of  the  Lower  and  Middle  Cambrian  occur  near 
Natural  Bridge  and  Balcony  Falls. 

W.  B.  Rogers  states,  in  connection  with  a  contribution  on  the  geology  of  Virginia  to 
Macfarlane's  Geological  Railway  Guide  (1879),  that  the  "Potsdam  or  Primal  Group, 
where  complete  hi  Virginia,  includes,  besides  the  Potsdam  sandstone  proper,  the  ferrife- 


468  HISTORICAL  GEOLOGY. 

rous  shales  next  above,  and  the  slates,  shaly  grits,  and  conglomerates,  below,  this  formation. 
It  is  exposed  on  the  western  slope  and  in  the  west  flanking  hills  of  the  Blue  Ridge,  through 
much  of  its  length,  often,  by  inversion,  dipping  to  the  southeast,  in  seeming  conformity 
beneath  the  older  rocks  of  the  Blue  Ridge,  but  often,  also,  resting  unconformably  upon  or 
against  them."  These  statements  are  cited  from  the  Reprint  of  the  Annual  Reports  of 
1835-1841,  and  Other  Papers  on  the  Geology  of  the  Virginias,  by  the  late  W.  B. 
Rogers,  1884. 

In  Tennessee,  the  Lower  Cambrian  comprises  the  u  Chilhowee  "  sandstones  of  Safford, 
and  beneath  these,  probably,  the  Ocoee  conglomerates  and  sandstones.  West  of  Cleveland, 
in  east  Tennessee,  it  includes  the  lower  part  of  the  Knox  sandstone  of  Safford  (the  Rome 
sandstone  of  Hayes,  in  Georgia),  and  the  thick  formation  of  limestone  and  shales  below  ; 
while  the  central  and  upper  portions  of  the  Rome  sandstone  are  Middle  Cambrian.  The 
same  succession  occurs  near  Knoxville.  The  Upper  Cambrian  is  probably  represented  by 
the  lower  2000'  of  the  Knox  dolomyte.  The  typical  New  York  fauna  of  the  Upper  Cam- 
brian has  not  been  recognized  along  the  Appalachians  in  Pennsylvania,  nor  to  the  south- 
west. Lower  Cambrian  fossils  have  been  observed  in  the  lower  part  of  the  Rome  sandstone 
near  Rome,  Ga.,  and  in  the  limestones  and  shales  of  the  Coosa  series,  in  Coosa  valley, 
Alabama,  north  and  south  of  Cedar  Bluff. 

In  northwestern  Michigan  and  Wisconsin,  south  of  Lake  Superior,  the  Lake  Superior 
sandstone,  on  the  borders  of  the  lake,  rests  unconformably  on  the  Keweenaw  formation, 
and  is  referred  to  the  Cambrian.  A  broad  area  of  Upper  and  Middle  Cambrian  with  fossils 
skirts  the  Archaean  area  on  the  east  and  south,  and  consists  of  crumbling  sandstone  and 
arenaceous  shale,  with,  in  some  places,  much  green  sand  (glauconite),  and  thin  beds  of 
limestone  ;  the  maximum  thickness  is  1000'.  The  quartzyte  occurring  in  isolated  hills  in 
the  drift-covered  region  of  Wisconsin  in  Barren  County,  and  at  Baraboo  in  Sauk  County 
(the  Baraboo  quartzyte),  is  made  Huronian  by  Chamberlin  and  Irving,  but  Lower  Cam- 
brian by  N.  H.  Winchell.  At  St.  Croix  River,  the  horizontally  bedded  Upper  Cambrian 
rests  on  upturned  red  beds,  which  are  Middle  or  Lower  Cambrian,  and  are  continuous  with 
the  pipestone  quartzyte  of  southwestern  Minnesota,  where  Lingulse  have  been  found; 
in  this  quartzyte,  the  pipestone  bed  (Catlinite),  used  for  making  pipe  bowls  by  the  Indians, 
is  a  layer  of  red  argillaceous  sandstone  about  a  foot  thick ;  the  rock  passing  south  into 
Iowa  is  the  "Sioux  quartzyte"  of  C.  A.  White,  and  extends  10  miles  into  Dakota  to 
Sioux  Falls. 

With  regard  to  the  fact  of  unconformability  with  the  Archsean  at  Carp  River,  Pro- 
fessor J.  D.  Whitney  states,  in  a  letter  to  the  author  of  Nov.  7,  1893,  that  "  nothing  could 
be  clearer"  ;  that  u  along  the  shores  of  Carp  River  and  throughout  the  adjacent  region,  the 
sandstone  strata  are  recognized  as  overlying  the  well-characterized  beds  of  a  much  older 
formation  which  I  designated  as  the  'Azoic  Series.'  At  Carp  River  the  nearly  horizontal 
unaltered  sandstone  strata  abut  against  and  overlie  the  vertical  edges  of  a  well-marked 
quartzyte."  The  Lower  Magnesian  series  of  Missouri,  excepting  the  First,  or  Upper,  lime- 
stone of  the  series,  and  the  underlying  Saccharoidal  sandstone,  is  Cambrian.  It  consists 
of  alternating  strata  of  dolomyte  and  sandstone.  This  Lower  Magnesian  series  of  Missouri 
is  the  Ozark  series  of  Broadhead. 

The  Keweenaw  beds  were  described  by  Foster  and  Whitney  in  1850,  1851,  and  referred 
to  the  age  of  the  Potsdam  or  Cambrian.  The  more  recent  reports  are  by  Irving  (1880,  1883, 
1885)  and  Chamberlin  (1883)  ;  and,  with  special  reference  to  copper  mining,  by  M.  E. 
Wadsworth  in  1880.  The  series  consists  of  an  upper  division,  consisting  of  ordinary  sand- 
stone and  shales,  free  from  igneous  material,  made  15,000'  thick  by  Irving,  and  a  lower 
division,  25,000'  to  30,000'  thick,  made  up  of  detrital  and  igneous  rocks,  but  chiefly  the 
latter.  Chamberlin  gives  the  same  aggregate  thickness,  45,000'.  The  igneous  rocks  are 
doleryte  (diabase)  with  porphyritic  and  amygdaloidal  varieties,  gabbros,  and  also  acid 
rocks  as  felsyte,  felsyte-porphyry,  and  others.  (For  a  full  account  of  the  rocks,  see  Irv- 
ing, Report  U.  S.  G.  S.,  v.,  4to,  1883.)  As  estimates  of  the  thickness  of  upturned  rocks 


PALEOZOIC   TIME  —  CAMBRIAN.  469 

are  always  more  or  less  doubtful,  the  above  figures  can  be  considered  at  the  best  as  only  ap- 
proximations. To  the  great  thickness  estimated  there  is  the  additional  source  of  doubt 
referred  to  on  page  451,  under  the  Archaean.  For  if  45,000',  the  temperature  in  the 
bottom  beds  would  have  been  1800°  F.,  supposing  the  increase  of  temperature  downward 
to  have  been  1°  F.  in  25  feet  of  descent,  or  only  twice  as  great  as  now ;  and  if  35,000', 
it  would  have  been  1500°  F.,  high  enough  for  the  complete  metamorphisin  of  the  lower 
beds  in  the  series.  And  yet  there  is  no  metamorphism. 

The  Animikie  group,  of  slates,  sandstones,  quartzyte,  etc.,  on  the  north  shore  of  Lake 
Superior,  at  the  east  end  of  Minnesota,  about  Grand  Portage  Bay  and  beyond,  has  inter- 
calations of  doleryte  (diabase),  gabbro,  and  other  rocks,  much  like  those  of  the  Keweenaw 
formation.  Supposed  tracks  or  trails  of  marine  animals,  mentioned  on  page  446,  are  the 
only  fossils  yet  found.  The  Cambrian  age  of  the  formation  is  considered  probable  by 
many  geologists.  The  igneous  intrusions  are  regarded  as  laccolithic  by  Lawson,  and  as 
related  in  time  to  those  of  the  Keweenaw  formation. 

Eastern  Eocky  Mountain  slope.  —  The  Cambrian  beds  of  the  Black  Hills  are  red 
sandstone  and  with  fossiliferous  limestone  above,  pertaining  to  the  Upper  Cambrian. 

In  central  Texas,  the  beds  of  the  Llano  formation  of  Walcott  are  confined  to  Llano 
and  Burnet  counties ;  they  rest  on  upturned  beds  referred  to  the  Algonkian  by  Walcott 
(page  447). 

Rocky  Mountain  region  and  Pacific  slope.  — Lower  Cambrian  beds  occur  in  the  Rocky 
Mountains  of  British  America,  on  the  Vermilion  and  Kicking  Horse  passes.  At  Cotton- 
wood  Canon  in  Utah,  the  great  section  of  the  Wasatch  has  at  bottom  3000'  of  quartzyte, 
and  above  this  250'  of  hard  shales,  affording  Lower  Cambrian  fossils,  some  of  them 
identical  with  eastern  species ;  then  succeed  Lower  Silurian  beds,  the  Upper  Cambrian 
being  absent.  Above  Ophir  City,  in  Oquirrh  Mountain,  fossils  occur  in  a  limestone  over 
sandstone,  the  whole  2300'  thick.  In  Nevada,  according  to  Walcott,  in  the  Eureka  dis- 
trict, a  section  of  conformable  high-dipping  beds  7700'  thick,  contains  below  (1)  1500' 
of  quartzyte ;  (2)  3050'  limestone,  with  Lower  Cambrian  fossils  in  the  lower  500';  (3)  1600' 
shale,  and  above  this  1200'  of  limestone,  350'  of  shale  affording  Upper  Cambrian  fossils 
at  bottom.  In  the  Highland  Range,  125  miles  south  of  the  last,  are  1450'  of  limestone 
and  shales  overlying  350'  quartzyte  which  are  Lower  Cambrian,  and  above  these,  3000' 
of  massive  limestone  which  are  Upper  Cambrian. 

Other  sections  occur  east  of  Pioche ;  at  Silver  Peak ;  at  the  south  end  of  the  Tim- 
pahute  Range.  In  Arizona,  at  the  Grand  Canon  of  the  Colorado,  3000'  to  5000'  deep, 
underneath  horizontal  Carboniferous  and  Subcarboniferous  beds,  the  lower  the  u  Red 
Wall  Group  "  of  Powell,  lie  horizontally  700'  to  800'  of  shales  and  sandstones,  the  Tonto 
group  of  Gilbert,  made  Upper  Cambrian ;  the  highly  tilted  beds  beneath  are  referred  by 
Walcott  to  the  Algonkian.  In  S.  E.  California,  Inyo  Co.,  Lower  Cambrian  (Wale.,  1894). 

For  an  extended  review  of  the  Cambrian  of  America  see  Bull.  81,  U.  8.  G.  S.  (1892),  by 
C.  D.  Walcott,  to  whom  the  science  is  indebted  for  the  discovery  of  the  larger  part  of  the 
facts. 

LIFE. 

The  life  of  the  Cambrian,  so  far  as  known,  was  marine.  The  plants  were 
Algae  (seaweed). 

The  animals  thus  far  made  out  from  the  fossils  are  all  Invertebrates. 
They  include  Sponges,  Corals,  Hydrozoans,  Echinoderms,  Worms,  Brachio- 
pods,  Mollusks  of  the  divisions  of  Lamellibranchs,  Pteropods,  Gastropods 
and  Cephalopods ;  and  also,  among  Arthropods,  Trilobites  and  other  Crusta- 
ceans. All  these  groups,  excepting  that  of  Cephalopods,  were  represented 
in  the  earliest  of  the  three  divisions  of  the  era. 


470 


HISTORICAL   GEOLOGY. 


1.  LOWER  CAMBRIAN. 

1.  Protozoans.  —  No  Rhizopod  remains  have  been  detected,  unless  small 
concretion-like  nodules,  concentric  in  structure,  occurring  crowdedly  in  a 
Cambrian  limestone  in  Nevada,  are  of  this  nature.     They  may  belong  to 
the  genus  Girvanella  (Walcott).     See  page  501. 

2.  Sponges,  Corals,  Graptolites.  —  Fig.  506  represents  one  of  the  Lower 
Cambrian  sponges,  Leptomitus  Zittelli  of  Walcott,  from  Georgia,  Vt. 

Figs.  507,  508  are  of  corals,  though  supposed,  when  described,  and  until 
investigated  microscopically  by  Hinde,  to  be  Sponges.  Fig.  507  represents  the 
Archceocyathus  profundus  of  Billings,  and  508,  508  a,  views  of  Spirocyathus 


506-509. 


506. 


507. 


508. 


609. 


508  a. 


SPONGE.  —  Fig.  506,  Leptomitus  Zittelli.  —  CORALS,  507,  Archaeocyathus  prof  undue;  508,  Spirocyathus  Atlan- 
ticus  (i) ;  508  a,  transverse  section.  —  GRAPTOLITB,  509,  Climacograptus  (?)  Emmonsi.  Figs.  506,  509, 
Walcott ;  507,  508,  Billings. 

Atlanticus  Billings.  One  of  the  early  Graptolites  (so  called  from  the  Greek 
ypa<£w,  write,  because  plume-like  in  form)  is  represented  in  Fig.  509,  doubt- 
fully placed  in  the  genus  Phyllograptus  by  Walcott,  under  the  name  Climaco- 
graptus (  ?)  Emmonsi. 

3.  Echinoderms.  —  Only  fragments  of  Cystoids,  related  to  Middle  Cam- 
brian species,  have  been  observed. 

4.  Worms.  —  Tracks  and  borings  of  sea-worms  or  Annelids  are  not  un- 
common.    Worm-borings,  called  Scolithus  (from  the  Greejt  for  worm),  occur 
in  the  Lower  Cambrian  sandstones  and  through  later  periods  to  the  present 
time :  no  distinction  of  species  or  genera  can  be  made  out. 


PALEOZOIC   TIME  —  CAMBRIAN. 


471 


5.  Brachiopods.  —  The  Articulate  Brachiopods  (or  those  in  which  the 
valves  are  hinged  together),  as  well  as  the  Inarticulate,  were  represented,  but 
most  abundantly  the  latter.  Figs.  510-513,  515  represent  some  of  the 
species  of  the  latter  division,  and  Figs.  514,  516-520,  some  of  the  former. 


510. 


511. 


510-520. 
511  a. 


512. 


512  a. 


BRACHIOPODS.  —  Fig.  510,  Lingulella  ccelata,  ventral  (2) ;  511,  L.  ella,  ventral  (2);  511  a,  same,  cant  of  interior 
of  dorsal  valve  (2) ;  512,  Acrotreta  gemma,  side  view  (3);  512  a,  same,  upper  view,  ventral  (3)  ;  513,  Obo- 
lella  crassa,  dorsal  (2):  513 a,  cast  of  interior  of  ventral  (2);  514,  Kutorgina  cinguhita,  ventral;  515, 
Ipnidea  bella;  516,  Ortbis  (?)  Highlandensis  of  Walcott,  dorsal  shell  mostly  worn  off  (1) ;  517,  Orthisina 
(Billingsella)  festinata  (i) ;  518,  O.  (B.)  orientalis,  ventral  (1) ;  519,  Orthis  Salemensis,  ventral;  520,  Camar- 
ella  (?)  autiquata,  ventral,  enlarged.  Figs,  from  Walcott;  510,  513,  after  Ford  ;  518,  after  Whitfield  ; 
515,  after  Billings. 

6.  Mollusks.  —  Figures  521,  522  represent  species  of  Lamellibranchs, 
each  of  very  small  size  (here  enlarged),  and  rare  fossils  ;  and  Figs.  523-525, 
several  Gastropods,  cap-like  in  form,  like  the  modern  Patella.  The  Platy- 
ceras  primcevum  of  Walcott  (Fig.  526)  has  a  short  spiral  at  the  summit,  a 
little  like  a  broad  horn,  and  hence  the  name,  from  the  Greek ;  the  genus  con- 
tinues to  the  Carboniferous  period,  and,  according  to  some  authors,  is  not 
generically  distinct  from  the  modern  genus  Capulus.  Pleurotomaria  Attle- 
borensis  is  another  Gastropod  from  North  Attleborough,  Mass. 

Other  eminently  characteristic  Mollusks  were  the  Pteropods  of  the  genera 
Hyolithes  and  Hyolithellus.  They  are  long,  conical,  thin  shells  like  Figs.  527, 
528.  The  large  end  was  closed  by  a  shell-like  operculum,  one  of  which,  of 
the  H.  Americanus  Walcott,  is  represented  in  Fig.  528  a.  The  Salterellae, 
Figs.  529,  530,  are  stout  shells,  probably  those  of  Pteropods.  Fig.  529,  S. 


472 


HISTORICAL  GEOLOGY. 


pulchella  Billings,  is  common  in  the  red  sandrock  of  Highgate  Springs,  Vt., 
and  the  Winooski  marble.     Fig.  530  is  the  same.     The  very  slender  species, 


521-526. 


521. 


522. 


523  a. 


MOLLUSKS.  —  Lamellibranchs  :  Fig.  521,  Fordilla  Troyensis  (enlarged) ;  521  a,  id.,  cast  of  interior;  522,  Mo- 
dioloides  priscus,  very  much  enlarged.  Gastropods :  523,  Scenella  reticulata;  523  a,  profile  as  seen  in  side 
view  showing  the  height  and  outline  of  the  conical  shell ;  524,  Scenella  retusa,  side  view  (3) ;  524  o,  same, 
upper  view;  525,  Stenotbeca  (?)  rugosa,  view  from  above  (1) ;  525 a,  5256,  same,  side  views;  526,  Platy- 
ceras  primaevum,  cast  (4).  Figures  from  Walcott ;  524,  524  a,  after  Ford. 

Fig.  531,  from  Troy,  is  the  type  of  the  genus  Hyolithellus  of  Ford.     Fig.  532 
is  the  operculum  of  Hyolithes  impar. 


527-532. 


527. 


528  a. 


529. 


530. 


531. 


529  a. 


532. 


PTBROPODS.  — Fig.  527,  Hyolithes  princeps  (1);  527  a,  outline  Of  cross-section;  528,  H.  Americanus  (2); 
528 a,  operculum  of  same;  529,  T30,  Salterella  pulchella;  529  b,  cross-section;  531,  Hyolithellus  micans  (1) ; 
532,  the  operculum  of  Hyolithes  impar.  Walcott. 


PALEOZOIC   TIME  —  CAMBRIAN. 


473 


7.  Crustaceans.  —  Trilobites,  the  highest  species  of  the  Cambrian  seas  yet 
discovered,  were  of  many  species  and  very  diverse  forms.  Figs.  535,  536  rep- 
resent some  of  the  species  of  the  genus  Olenellus ;  Fig.  535,  O.  Vermontanus 


635. 


533-639. 
534. 


539. 


TRILOBITES.  —  Fig.  533,  Agnostus  nobilis,  two  middle  segments  absent  (1) ;  534,  Microdiscus  speciosua  (2) ; 
535,  Olenellus  (Mesonacis)  Vermontanus  (1) ;  536,  Olenellus  Thompson!  (1,  £  max.  size) ;  537,  Bathy- 
notus  holopyga,  distorted  (1) ;  538,  Olenpides  Fordi,  head-shield  without  the  cheek  (2) ;  538  a,  separated 
cheek;  538  6,  same,  pygidium  (caudal  extremity);  539,  Ptychoparia  Adamsi.  Figs,  from  "Walcott; 
533,  after  Ford. 

Walcott ;  Fig.  536,  0.  Thompsoni  Hall.  These  species  from  Georgia,  Vt.,  are 
over  six  inches  long ;  the  latter  occurs  also  in  western  Newfoundland.  The 
Olenellus  Gilberti  Meek  (Fig.  540)  is  a  fine  species  from  Nevada  and  Utah. 
Another  large  species,  0.  asaphoides  of  Emmons,  is  from  near  Bald  Mountain 
and  Troy,  Washington  County,  N.Y.  Emmons  cited  it  as  characteristic  of 
the  "Upper  Taconic."  The  Bathynotus  (Fig.  537),  remarkable  for  the  long 
spines  of  its  head-shield,  is  another  Trilobite  of  large  size,  from  Georgia,  Vt. 
The  genera  Agnostus  and  Microdiscus  include  small  species,  differing  in  the 
former  having  two  segments  between  the  head  and  caudal  shield,  and  the 
latter  three. 


474 


HISTORICAL   GEOLOGY. 


The  other  Crustaceans  pertain  to  two  still  existing  tribes  of  Entomostra- 


cans,  the  Ostracoids  and  the  Phyllopods. 
Ostracoids  from  Wash- 
ington County,  N.Y. ; 
the  dot  in  Fig.  541 
shows  the  position  of 
the  eye.  Fig.  543  is 
the  Phyllopod,  Protoco- 
ls Marshi  Walcott,  from 
Georgia,  Vt.  The  shell 
may  owe  its  flattened 
form  to  pressure. 

Doubtful  tracks.  — 
The  slender  impressions 
of  rounded  surface  that 
have  been  referred  to 
seaweeds  (Fucoids)  may 
those  of  Worms  or  Mollusks.  Another 


Figs.  541   and  542   represent 


Olenellue  Gilbert!  Meek. 


be 


CRUSTACEANS.  —  Fig.  641,  Leperditia  der- 
matoides;  542,  Aristozoe  rotundata; 
543,  Protocaris  Marshi  (£).  Figs,  from 
Walcott. 


544. 


545. 


kind,  having  a  longitudinal  impression  along 

the  middle,  called  Cruziana  (D'Orbigny)  and 

Bilobites  (De  Kay),  are  regarded  as  the  tracks  of  Annelids,  Mollusks,  or  some 

other  Invertebrate.     Fine  Lower  Cambrian  examples  are  figured  by  Walcott. 

2.  MIDDLE  CAMBRIAN. 

The  range  of  life  in  the  Middle  Cambrian  is  the  same  nearly  as  in  the 
Lower,  but  the  species  are  mostly  different,  and  in  place  of  the  genus  Olenel- 
lus  among  Trilobites,  Paradoxides  has  special  prominence. 

1.  Sponges,  Echinoderms.  — 
Remains  of  Sponges  occur  in 
Nevada  and  New  Brunswick. 
The  spicules,  Fig.  544,  are  from 
Nevada  and  are  referred  doubt- 
fully to  the  Protospongia  fene- 
strata  of  Salter.  Some  simple 
forms  of  Graptolites  have  been 
found  in  New  Brunswick. 

Cystoids  are  the  prevailing 
Echinoderms.  A  Nevada  speci- 
men (Fig.  545)  has  the  usual 
box-like  body  (whence  the  name 
cystoid,  from  the  Greek),  with 
unsym metrically  arranged  arms 
(mutilated  in  the  specimen),  and 
the  body-plates  of  irregular  forms 
(Fig.  545  a).  Plates  of  Eocystites  were  first  reported  from  New  Brunswick. 


545  a. 


SPONGE.  — Fig.  544,  Spicules;  Protospongia  fenestrata(?) ; 
545,  Eocystites  (?)  longidactylus;  545  a,  plates  of  portion 
of  body  enlarged.  Figs,  from  Walcott. 


PALEOZOIC   TIME  —  CAMBRIAN. 


475 


546. 


547. 


2.  Brachiopods.  —  The  following  are  enlarged  figures  of   some   of  the 
forms  found  in  New  Brunswick. 

3.  Mollusks.  —  Ptero-  546-549. 
pods  are  still  very  common 

(Figs.  527-531) .  Two  sup- 
posed Gastropods  are  from 
New  Brunswick.  Fig..  552 
represents  Stenotheca  Aca- 
dica,  originally  supposed  to 
be  a  Brachiopod  of  the 
genus  Discina,  but  now 
placed  among  the  Gastro- 
pods. Fig.  553  is  a  greatly 
enlarged  view  of  Harttia 
Matthewi  Walcott,  referred 
to  the  Calyptraea  family, 
the  cap-like  shell  having  a 
smaller  cap  within. 

4.  Crustaceans.  —  Some  of  the  Paradoxides  are  the  largest  of  Trilobites. 
P.  Harlani  (Fig.  556),  the  first  known  of  American  species,  from  Braintree, 
near  Boston,  has  a  length  of  10  inches,  and  a  breadth  two-thirds  as  great,  in 
some  specimens ;  and  the  spines  at  the  posterior  angle  of  the  cheek-piece  of 


BRACHIOPODS.  —  Fig.  546,  Acrothele  Matthewi  (2) ;  547,  Linnara- 
eonia  transverea  (8) ;  548,  Lingulella  Dawsoni  (1) ;  549,  549  a, 
Orthis  (Protorthis)  Billings!.  Figs.  546,  547,  549,  from  Walcott; 
548,  from  Hartt. 


550-553. 


551. 


553. 


550. 


PTKKOPODS  and  GASTROPODS.  — Fig.  550,  Hyolithes  Acadicus  (1)  ;  551,  H.  Danianus  (1)  ;  552,  Stenotheca 
Acadica  (2) ;  553,  Harttia  Matthewi  (12).    Figs,  from  Walcott. 

the  head  (the  piece  bounded  by  a  suture  passing  by  the  eye)  are  nearly  half 
as  long  as  the  animal.  (In  Fig.  556  they  are  shorter  than  usual.)  P.  Ben- 
netti  Salter,  from  Newfoundland,  was  11  inches  long  and  9^-  broad ;  and  P. 
Regina  Matthew  (Fig.  557)  from  New  Brunswick,  15  inches  long  and  11 
broad.  Fig.  554  shows  the  form  of  an  Agnostus.  In  Fig.  555  the  free 
segments  are  absent. 


476 


HISTORICAL   GEOLOGY. 


Fig.  562  represents  one  of  the  largest  of  Ostracoid  Crustaceans,  —  the 
Leperditia  ( f)  Argenta  Wale.,  from  Argenta,  Big  Cottonwood  Canon,  Utah. 

554-561. 
556.  558.  557. 


TBILOBITES.  — Fig.  554,  Agnostus  interstrictus  (4) ;  555,  A.  Acadicus,  head  and  tail  shields;  556,  Paradoxides 
Harlani  (J)  restored;  557,  P.  Regina  (£) ;  558,  Bathyuriscus  Howelli,  pygidiura  (2);  559,  Ptychoparia 
Kingi  (J);  560,  Pt.  formosa,  head  (2);  561,  Pt.  Matthewi  (2).  Fig.  554,  558,  561,  from  Walcott;  555, 
556, Meek;  557,  Matthew. 

The  Caridoid  Phyllopods  are  supposed  to  be  represented  by  the  Ano- 
malocaris  Canadensis  of  Whiteaves,  a  mutilated  specimen  of  which  is 
shown,  natural  size,  in  Fig.  563.  It  is  from  the  Middle  Cambrian  shale  at 
Mount  Stephens,  British  Columbia. 

3.   UPPER  CAMBRIAN. 

The  typical  Upper  Cambrian  rocks  are  the  Potsdam  sandstone  of  the 
north  and  east  sides  of  the  Adirondacks  and  adjoining  parts  of  Canada. 
Sandstones  of  the  same  age  occur  in  South  Dakota,  Wyoming,  Montana,  and 
Colorado  ;  shales  and  sandstones  in  Newfoundland,  Cape  Breton,  New  Bruns- 
wick, and  at  some  localities  along  the  Appalachian  province  southwest  of 


PALEOZOIC   TIME  —  CAMBRIAN. 


477 


662. 


New  York.  Sandstones  and  calcareous  beds  represent  the  Upper  Cambrian  in 
Arizona  and  Texas,  and 
limestones  and  shales  in 
Nevada,  Idaho,  and  Mon- 
tana, and  probably  in 
British  Columbia. 

The  chief  character- 
istic of  the  Fauna,  dis- 
tinguishing it  from  that 
of  the  preceding  epoch, 
is  the  almost  total  inde- 
pendence in  species,  so 
far  as  now  known;  the 
absence  of  Paradoxides, 
and  the  substitution  of 
Trilobites  of  the  genus 
Dicellocephalus,  of 
which  30  species  have 
been  described ;  and, 
further,  the  multiplica- 
tion of  Gastropods  of 
coiled  forms. 

1.  Rhizopods,  Sponges,  Graptolites,  Cystoids.  —  The  green  sand  of  the  beds  of 
Wisconsin  is  probable  evidence-  of  the  abundant  presence 
of  Rhizopods,  since  similar  grains  from  later  rocks  were 
shown  by  Ehrenberg  to  have  the  form  of  casts  of  the  in- 
terior of  Rhizopod  shells.  Remains  of  Sponges  and  of 
Cystoids,  allied  to  those  of  the  earlier  Cambrian,  occur  in  the 
beds.  One  of  the  Graptolites  is  represented  in  Fig.  564, 
and  a  branch  of  the  same  enlarged  in  Fig.  565. 

2.  Worms. —  The  Scolithus  (S.  linearis)  from  the  Potsdam 
sandstone  is  represented  in  Fig.  566.     The  fossil  is  the  filling  of  the  vertical 
burrow  made  by  the  worm  in  the  sand. 


CRUSTACEANS.  —  Fig.  562,  Leperditia  Argeuta  Wale. ; 
563,  Anomalocaris  Canadenaia  (1)  Whiteavea. 


564. 


665. 


Dendrograptua    Hal- 
lianua.    Prout. 


566. 


567. 


Fig.  566,  Scolithus  linearis.    Hall. 


567,  Cruziana  similis,  supposed  track  of  a  worm.    Billings. 


478 


HISTORICAL   GEOLOGY. 


The  peculiar  markings,  obliquely  furrowed  from  a  medial  line  named 
Cruziana  similis,  by  Billings,  have  been  supposed  to  be  plants,  but  are  now 
regarded  as  the  tracks  of  worms  or  some  other  animal  (Fig.  567). 

3.   Brachiopods.  —  The  following  are  figures  of  a  few  species  :  — 


568. 


569. 


573. 


BRACHIOPODS.  —Fig.  568,  Lingulepis  antiqua  (1);  569,  570,  Lingulella  prima  (1);  571,  572,  Obolella  polita  (1)  ; 
573,  Triplesia  (Camarella?)  primordialis.    Fig.  568-570,  Hall;  571,  572,  Meek  ;  573,  Walcott. 

The  Lingulids  are  so  abundant  in  some  places  that  they  give  the  beds  a 
shaly  structure. 

4.  Pteropods.  —  Fig.  574  is  a  Hyolithes,  from  the  Big  Horn  Mountains. 
Fig.  575  is  a  peculiar,  rather  thick,  conical  shell,  doubtfully  referred  by 
Walcott  to  the  Pteropods.     It  is  oval  below  in  outline,  and  has  an  opercu- 
lum  like  that  of  Hyolithes. 

5.  Gastropods.  —  The  Gastropods  here  figured  (Figs.  578-582)  pertain  to 
genera  that,  like  Platyceras  of  the  Lower  Cambrian,  are  characteristic  emi- 
nently of  more  or  less  of  later  Paleozoic  time.     Bellerophon  has  the  shell 


574. 


574-582. 


578. 


579. 


581. 


675. 


PTEROPODS.  —Fig.  574,  Hyolithes  gregarius  (1);  575,  Matberia  variabilie,  lateral  view  (3) ;  576,  577,  same,  end 
views  of  different  specimens  (1).  Q-ASTKOPODS.  — Fig.  578,  Holopea  Sweeti;  579,  580,  Ophileta  primor- 
dialis; 581,  582,  Bellerophon  antiquatus.  Fig.  574,  from  Meek;  575-577,  Walcott;  578-582,  Whitfield, 
Wisconsin  G.  Rep. 

coiled  in  a  plane ;  it  has  also  (but  not  shown  here)  a  narrow  slit  in  the  lip 
of  the  shell  at  its  middle.  B.  antiquatus  Whitf.,  first  described  from  Wis- 
consin beds  (Fig.  581),  occurs  also  in  Eureka,  Nev. 

6.  Trilobites.  —  Fig.  583  represents,  reduced,  one  of  the  large  species  of 
Dicellocephalus  of  Owen,  from  Minnesota,  —  the  real  length  being  six  inches. 
Figs.  585  and  585  a  are  head  and  pygidium  of  one  of  the  small  species 


V 


PALEOZOIC   TIME  —  CAMBRIAN. 


479 


from  the  Potsdam  sandstone  of  Keeseville,  N.Y.,  the  total  length  being  a 
fourth  of  an  inch.  The  track,  5£  inches  broad,  Fig.  586,  from  Perth,  Canada, 
described  by  Logan,  has  been  referred  to  a  large  Trilobite,  on  the  view  that 
the  limbs  of  the  species  were  natatory ;  and  on  587  is  a  similar  track,  4? 
inches  broad,  from  New  Lisbon,  Wis.,  besides  a  still  smaller  kind.  The 
partially  natatory  character  of  the  limbs  has  been  recently  established  by 
Beecher  (page  512). 

583-588. 
583.  585.  586. 


TBILOBITES.  — Fig.  583,  Dicellocephalus  Minnesotensis  (J) ;  584,  D.  lowensis  (1)  ;  585,  Ptychoparia  (Cono- 
coryphe)  minuta,  head  shield  (4);  585  a,  same,  pygidium  (4).  TRACKS.  — Fig.  586,  Climactichnites 
Wilsoni,  supposed  to  be  those  of  a  large  Trilobite  (f) ;  587,  Climacticbnites  Youngi  (the  larger  track), 
with  C.  Fosteri,  the  smaller;  588,  Protichnites  eeptemnotatua.  Fig.  583,  584,  from  D.  D.  Owen;  585, 
586  a,  F.  H.  Bradley;  586,  588,  Logan;  587,  Chamberlin. 

The  tracks,  a  portion  of  the  series  of  which  is  represented  in  Fig.  588, 
were  described  by  Owen  from  specimens  found  in  the  Potsdam  sandstone  of 
Canada.  The  breadth  of  the  pairs  of  tracks  was  six  to  seven  inches.  What 
made  them  is  not  yet  known. 

Besides  the  kinds  of  fossils  mentioned  above,  there  are  also  various  markings  and  im- 
pressions that  are  not  fully  explained.  Among  these  are  impressions  4-sided,  5-sided, 
and  circular  in  form,  from  Olenellus  beds,  which  have  been  referred,  first  by  Nathorst  of 
Sweden,  and  later  by  Walcott  and  others,  to  Hydrozoans  or  Medusae  of  large  size.  The 


480  HISTORICAL   GEOLOGY. 

5-sided  forms  among  them,  and  the  thickness  indicated,  make  a  relation  to  the  Medusse 
doubtful.  Nathorst  states,  however,  that  he  has  experimented  with  some  species  of  Me- 
dusae and  obtained  similar  impressions.  Moreover,  some  modern  Medusse  have  occasion- 
ally varieties  with  five  divisions. 

A  general  review  of  the  fossils  of  the  Lower,  Middle,  and  Upper  Cambrian  will  be 
found  in  Walcott's  papers  :  Bulletins  U.  S.  Geol.  Survey,  Nos.  10,  30,  and  81,  and  Tenth 
Ann.  Bep.  U.  S.  Geol,  Survey ;  and  details  here  are  therefore  unnecessary. 

See,  also,  papers  by  Billings,  Palaeozoic  Fossils,  Canada  Survey ;  J.  W.  Salter,  Q.  J. 
G.  Soc.,  xv.,  551,  1859 ;  James  Hall,  Sixteenth  Ann.  Report,  N.  Y.  State  Cabinet,  pp. 
119-184, 1863;  G.  F.  Matthew,  Royal  Soc.  Canada  Proc.  and  Trans.,  vols.  i.-v.,  vii.-ix. ; 
C.  F.  Hartt,  in  Dawson's  Acadian  Geology ;  S.  W.  Ford,  Am.  Jour.  Sc.,  3d  series,  vols.  2, 
3,  5,  11,  13,  15,  19,  21,  22  ;  Rominger,  Phil.  Acad.  Sc.  Proc.  1887,  p.  12  ;  Whiteaves,  Am. 
Jour.  Sc.,  3d  series,  xvi.,  224  ;  Whitfield,  Geol.  Survey  Wis.,  iv.,  and  Am.  Mus.  Nat.  Hist. 
Bull.,  i.,  p.  139  ;  Shaler  and  Foerste,  Bull.  Mus.  Comp.  Zool.  Camb.,  xvi.,  115,  1888  ;  also 
Walcott,  Am.  Jour.  Sc.,  xxxiv.,  xxxvi.,  and  U.  S.  Nat.  Mus.  Proc.,  vols.  xi.-xiii.  Besides 
the  above,  there  are  recent  studies  of  the  Genera  of  Cambrian  Brachiopods  by  Hall  and 
Clarke  (Pal.  N.Y.,  vol.  viii.,  1892);  a  paper  on  the  Classification  of  the  Brachiopods  by 
C.  Schuchert  (Am.  Geologist,  March,  1893) ;  and  a  paper  on  the  Development  of  Brachio- 
pods by  C.  E.  Beecher  (Am.  Jour.  Sc.,  xli.,  1891).  Beecher  separates  from  the  genus 
Kutorgina  of  Billings  (the  type  of  which  is  K.  cingulata,  an  articulate  Brachiopod)  the 
species  Kutorgina  (Obolus)  Labradorica  of  Billings,  var.  Swantonensis  of  Walcott  (which 
is  inarticulate  and  undergoes  no  modification  of  form  during  growth),  and  makes  it  the 
type  of  the  new  genus  Paterina. 

The  investigation  of  the  Cambrian  rocks,  in  late  years,  has  greatly  increased  the 
number  of  known  species.  An  extended  description  of  the  Lower  Cambrian  fauna  is 
published  in  the  Tenth  Ann.  Report  of  the  U.  S.  Geol.  Survey,  1890,  by  Walcott.  Mat- 
thew has  described  many  species  of  the  Middle  Cambrian,  and  the  Upper  Cambrian  faunas 
are  being  studied  by  Walcott.  Over  100  genera  and  400  species  are  already  described 
from  the  Cambrian  of  North  America.  Walcott  gives  the  following  table  of  the  number 
of  genera  and  species  of  fossils  in  the  Lower  Cambrian  alone  of  North  America  (1890):  — 

Gen.  Sp.                                                                          Gen.  Sp. 

Spongiozoans 4  4  Brachiopods 10  20 

Hydrozoans 2  2  Gastropods 6  15 

Actinozoans 5  9  Pteropods 4  15 

Echinoderms 1  1  Trilobites 15  51 

Tracks,  trails,  burrows .     .    4  6  Other  Crustaceans     ...    6  8 

Total    .     .  56    131 

Adding  species  not  included  above,  mostly  described  by  G.  F.  Matthew,  of  New 
Brunswick,  the  total  number  of  American  genera  is  nearly  70,  and  of  species  170. 


FOREIGN. 

The  Cambrian  rocks  of  Great  Britain  outcrop  in  North  and  South  Wales, 
and  in  Shropshire,  just  east  of  Wales.  The  principal  regions  identified  by 
fossils  are  the  Longmynd,  of  slate  and  grits,  in  Shropshire ;  the  Harlech, 
and  the  Bangor  and  Llanberis  toward  the  Menai  Straits,  of  sandstones,  flags, 
and  slates,  in  North  Wales  ;  the  St.  Davids  (ancient  Menevia),  of  sand- 
stones, slates,  grits,  and  conglomerate,  in  South  Wales  ;  and  that  of  the 
Malvern  Hills.  In  Ireland,  Cambrian  rocks  occur  at  Brayhead  and  in  Wex- 


PALEOZOIC   TIME  —  CAMBRIAN. 


481 


ford,  County  of  Wicklow.  Other  reported  regions,  partly  metamorphic,  are 
those  of  Charnwood  Forest,  and  the  Western  Highlands  of  Scotland. 

The  lower  part  of  the  Cambrian  of  St.  Davids  is  divided  by  Dr.  Hicks 
into  (I)  the  Caerfai  group,  (2)  the  Solva,  and  (3)  the  Menevian.  The 
Lower  Cambrian  includes  (according  to  Walcott)  the  first  of  these  groups  ; 
it  contains  Lingulella  primceva,  L.  ferruginea,  Discina  Caerfaiensis,  Leperditia 
Cambrensis,  but  no  Olenellus  has  been  reported.  To  it,  as  Lapworth  shows, 
belong  also  sandstone  beds  in  Shropshire,  from  which  he  has  described 
Olenellus  Callavei  (with  which  occur  species  of  Kutorgina,  Acrothele,  etc.). 
There  are  there  no  overlying  Paradoxides  beds.  Here  belong  also  the 
sandstones,  flags,  and  slates  of  Bangor  and  Llanberis,  toward  the  Menai 
Straits. 

The  Middle  Cambrian  or  Paradoxides  section  comprises  the  Solva  and 
Menevian  beds  of  St.  Davids,  which  have  afforded  Paradoxides  Harknessi, 
P.  Solvensis,  P.  Davidis,  with  Protospongia  fenestrata  and  species  of  Lingulella, 
Theca  or  Hyolithes,  Discina,  Orthis  (Orthisina),  Stenotheca,  Agnostus,  Micro- 
discus,  Conocoryphe,  Leperditia.  The  Lower  Cambrian  and  part  of  the 
Middle  of  Sedgwick  are  here  included. 

The  Upper  Cambrian  or  Olenus  division  comprises  the  Lingula  flags  and 
Tremadoc  slates,  which  occur  along  by  Maentwrog,  Festiniog,  and  Dolgelly 
in  North  Wales,  and  the  Tremadoc  beds  both  in  North  Wales  and  at  St. 
Davids. 

The  genus  Olenus  here  has  its  largest  development.  The  beds  include 
also  Dictyonema,  and  other  Graptolites ;  species  of  Lingulella,  as  L.  Da- 
visi  (Fig.  591),  Lingula,  Obolella,  Kutorgina,  Orthis;  Hyolithes,  Conularia, 


589-595. 


595 


Fig.  589,Oldhamiaantiqua;  590,  O.  radiata;  591,  Lingulella  Davisi;  592,  Agnostus  Rex;  593, 
Olenus  micrurus  ;  594,  Sao  hireuta  (£)  ;  595,  Hymenocafia  vermicauda  (J). 

Bellerophon  (B.  Cambrensis) ;  among  Trilobites  the  genera  Agnostus,  Cono- 
coryphe, Ampyx,  Olenus  (among  the  many  species,  Olenus  micrurus,  Fig.  593), 
Dicellocephalus,  Sphcerophthalmus  ;  also  the  Crustacean  Ostracoids,  Leper- 
ditia, Primitia  ;  the  Caridoid  species,  Hymenocaris  vermicauda  (Fig.  595). 
In  the  Tremadoc  slates  occur  several  species  of  Graptolites ;  Dendrocrinus 
Cambrensis  and  Palceaster,  among  the  earliest  Echinoderms ;  Lamellibranchs 
of  the  genera  Modiolopsis,  Palcearca,  Ctenodonta,  etc. ;  Pteropods  of  the  genera 
Theca  and  Conularia ;  the  earlier  of  British  Cephalopods,  of  the  genera  Ortho- 
DANA'S  MANUAL,  —  31 


482  HISTORICAL   GEOLOGY. 

ceras  and  Cyrtoceras;  among  Trilobites,  the  genera  Olenus,  Agnostus,  Asaphus, 
Ogygia,  Conocoryphe,  Cheirurus;  and  the  Caridoid  Entomostracans,  Cera- 
tiocaris  and  Lingulocaris. 

Oldhamia,  from  the  Bray  Head  region,  Ireland  (Figs.  589,  590),  has  been 
supposed  to  be  a  seaweed,  and  also  Hydrozoan.  It  is  stated  by  Dr.  Kinahan 
to  be  only  inorganic  markings. 

In  Scandinavia,  where  the  Olenellus  zone  was  first  shown  to  be  the  true 
Lower  Cambrian  by  Dr.  A.  G.  Nathorst,  the  Lower  beds  occur  at  Andraruin 
in  Scania  beneath  Paradoxides  beds.  They  are  also  found  near  Lake  Mosen 
in  Norway,  and  in  Esthonia  in  Russia.  They  have  afforded,  besides  Olenellus 
Kjerulfi,  species  of  Lingulella,  Obolus,  Discina(?),  Hyolithes,  Metoptoma, 
Scenella,  and  also  impressions  which,  as  stated  above,  page  479,  are  referred 
by  Nathorst  to  Medusae  and  called  Medusites.  The  Middle  Cambrian 
beds  near  Kongsberg,  Norway,  contain  Paradoxides  Tessini,  P.  Forchhammeri, 
Agnostus  Kjerulfi,  with  Protospongia ;  and  in  Sweden,  the  same  species  of 
Olenellus  with  Paradoxides  beds  at  a  higher  level,  and  above  these  Olenus 
schists  and  Dictyonema  shales. 

The  Cambrian  beds  of  Norway  are  very  thin,  the  beds  near  Kongsberg 
being  60  feet  thick ;  in  Sweden,  the  thickness  is  2000  feet.  The  Eophyton 
sandstone  lies  beneath  the  Olenellus  beds  in  Norway  and  contains  the  am- 
biguous Eophyton  with  Hyolithes  levigatus,  and  worm  and  other  doubtful 
markings.  Nathorst  supposes  the  Eophyton  to  be  the  casts  of  trails  of 
Medusites. 

In  Bohemia,  the  region  of  Barrande's  discoveries,  —  an  area  about  Prague 
having  Archaean  rocks  around  it  except  on  the  north  and  northeast,  —  the 
"Primordial  zone/'  his  stage  C,  300  to  400  yards  thick,  afforded  him  the 
genera  of  Trilobites,  Paradoxides  (12  species),  Agnostus  (5,  among  them  A. 
Rex,  Fig.  592),  Conocoryphe  (4),  Ellipsocephalus  (2),  Hydrocephalus  (2), 
Arionellus  (1),  Sao  (Sao  hirsuta,  Fig.  594)  ;  also  five  species  of  Cystoids,  with 
species  of  Orthis,  Orbicula,  and  five  of  Hyolithes.  From  the  underlying  beds 
of  stage  B  (which  rest  on  the  Archaean,  stage  A),  consisting  of  slates, 
quartzytes,  schists,  etc.,  Barrande  reported  traces  of  Annelids,  Arenicolites. 
Barrande  represents  the  rocks  in  a  section  across  from  northeast  to  south- 
west as  lying  in  a  simple  synclinal,  with  an  elevation  of  conformable  Upper 
Silurian  strata  at  the  center  of  the  synclinal. 

On  Sardinia  occur' Cambrian  beds,  from  which  Meneghini  described,  in 
1888,  two  species  of  Paradoxides,  several  of  Olenus,  and  Conocephalites,  with 
others  of  Anomocare  and  Asaphus.  No  species  of  the  Olenellus  horizon 
were  reported.  J.  G.  Bornemann  described  from  Sardinia,  in  1892,  Trilobites 
of  the  new  genera  Olenopsis,  Metadoxides,  and  Giordanella,  with  Gastropods 
of  the  genera  Capulus,  Bellerophon,  and  probably  Carinaropsis. 

In  the  province  of  Sian-tung,  China,  Cambrian  fossils  were  gathered  by 
von  Kichthofen,  and  identified  by  Dames  as  belonging  to  the  genus  Doro- 
pyge,  and  referred  to  the  age  of  the  Quebec  group.  Walcott  refers  them  to 
the  genus  Olenoides,  and  to  the  age  of  the  Middle  Cambrian. 


PALEOZOIC   TIME  —  CAMBRIAN*  483 

In  India,  the  Director  of  the  Survey  reports  the  discovery,  by  Dr.  Warth, 
of  two  Trilobites  in  the  Neobolus  beds  of  the  Salt  Range,  and  the  identi- 
fication, by  Dr.  Waagen,  of  one  of  them  as  a  species  of  Conocephalites,  and 
of  the  other  as  probably  an  Olenus;  thus  indicating  the  presence  of  a  Cam- 
brian and  probably  Lower  Cambrian  fauna. 

Species  of  Conocephalites,  Dicellocephalus,  Ethmophyllum,  and  several 
other  Cambrian  genera,  have  been  discovered  in  the  rocks  of  South  Australia. 

Kayser  described,  in  1876,  a  number  of  Brachiopods  and  an  Olenus  from 
the  northern  part  of  the  Argentine  Republic,  thus  indicating  Upper  Cambrian 
rocks  in  South  America. 


GEOGRAPHICAL  AND  PHYSICAL  CONDITIONS  AND  PROGRESS. 

American.  —  Cambrian  history,  as  the  facts  presented  show,  is  the  history 
of  a  begun  and  a  growing  continent ;  growing  not  by  extension  seaward,  but 
by  progress  in  rock-making  over  its  wide  surface  wherever  sufficiently  sub- 
merged, and  in  rock  destruction  over  emerged  areas  as  a  source  of  material 
for  the  new  rocks.  The  abundance  of  shells  of  Pteropods  may  seem  to 
indicate  deep  waters,  since  they  now  abound  in  sea-bottom  deposits  at  depths 
of  100  to  1000  fathoms  in  the  seas  of  the  Mexican  Gulf.  But  these  pelagic 
species  live  at  or  near  the  surface  ;  and  if  any  physical  conclusion  is  to  be 
inferred  from  their  abundance,  it  is  simply  that  the  surface  of  the  water 
was  between  70°  F.  and  85°  F. 

The  gathering  of  building-material  in  gradually  deepening  geosynclines 
or  troughs  for  future  mountain  ranges  in  the  neighborhood  of  the  Appala- 
chian and  Rocky  Mountain  protaxes  has  been  stated  to  have  commenced 
(page  357)  with  the  beginning  of  Paleozoic  time.  The  Cambrian  formations 
bear  testimony  to  the  fact ;  for  they  have  a  great  thickness,  thousands  of 
feet,  over  the  sites  of  the  Taconic  and  Appalachian  ranges,  west,  for  the  most 
part,  of  the  eastern  protaxis,  and  over  that  of  the  future  Laramide  or  post- 
Cretaceous  Range,  partly  east  and  partly  west  of  the  western  protaxis.  Even 
in  the  Lower  Cambrian  a  large  part  of  this  thickness  was  attained ;  while 
through  the  interior  basin  of  North  America,  as  far  as  the  facts  are  known, 
the  Cambrian  is  thin,  and  the  Lower  and  Middle  Cambrian  wanting.  Wal- 
cott's  map,  in  the  U.  S.  Q.  S.,  Tenth  Ann.  Report,  presents  the  probable  con- 
dition, and  sustains  his  view  of  very  uniform  conditions  over  the  interior, 
which  signifies  either  emergence  of  the  land  or  but  small  submergence,  and 
no  subsidence  in  progress. 

In  the  Lake  Superior  region,  along  the  southern  margin  of  the  Archaean  V, 
between  it  and  the  Archaean  area  of  Wisconsin,  there  was  one  great  exception 
to  uniformity  over  the  interior  continental  area.  But  it  was  apparently  con- 
fined to  the  Keweenaw  area,  where  there  were  extensive  igneous  eruptions. 
The  igneous  rocks  of  Isle  Royale,  in  Lake  Superior,  are  referred  to  the  same 
epoch  by  Whitney.  Similar  ejections  took  place  also  in  Michipicoten  Island, 
and  at  Thunder  Bay  and  other  points  along  the  north  shore  of  the  lake ;  but 


484  HISTORICAL   GEOLOGY. 

their  relations  to  those  of  Keweenaw  are  not  ascertained.  Igneous  outflows 
occurred  also  in  the  Cambrian  areas  of  southeastern  Pennsylvania  (G.  H. 
Williams,  1892). 

Foreign.  —  As  in  America,  Cambrian  beds  are  found  along  the  borders  of 
the  Archaean.  They  occur  at  various  points  in  the  northern  part  of  the 
Continent  of  Europe,  from  England  along  Sweden,  Norway,  Lapland,  to 
Esthonia,  in  Kussia,  and  also  about  isolated  areas  in  France,  Portugal,  and 
Spain ;  the  areas  being  the  outcropping  margins  of  Cambrian  deposits.  So 
large  a  part  of  the  European  continent  is  under  Mesozoic  or  Cenozoic  strata 
that  geology  cannot  claim  to  know  much  about  the  actual  distribution  of  the 
Cambrian  areas. 

Epochs  of  upturning  in  the  course  of  the  Cambrian.  —  Besides  evidence  of 
slow  change  of  level,  evidence  exists  of  one  or  more  epochs  of  disturbance  or 
upturning  during  the  long  interval  between  the  Archaean  and  the  close  of  the 
Cambrian.  The  evidence  consists  of  superposition  of  the  horizontal  or  nearly 
horizontal  beds  of  the  Upper  Cambrian  on  upturned  beds  of  earlier  Cambrian 
in  Minnesota,  on  the  St.  Croix,  in  central  Texas,  and  in  Arizona  in  the  Grand 
Canon  of  the  Colorado.  It  is  not  known  that  any  mountains  were  made  at 
the  time  in  either  of  the  three  regions  mentioned.  In  the  Eureka  district, 
Nevada,  the  beds  of  the  Upper  and  Lower  Cambrian  are  conformable. 

Tide  and  currents  the  same  essentially  as  now.  —  The  beach  material  of  the 
early  and  later  Cambrian  was  fine  sands  and  pebbles,  as  it  is  now ;  for  these 
are  the  materials  of  the  beach-made  rocks, — the  Potsdam  sandstone  and 
other  like  deposits.  They  were  as  quietly  belabored  by  the  waves,  as  the 
ripple-marks  show;  as  free  from  extraordinary  current  movements,  as  proved 
by  the  usual  even  regularity  of  the  bedding.  A  reddish  variety  of  these 
sand-made  rocks,  spread  out  and  accumulated  on  Cambrian  beaches  or  sand- 
flats,  is  used  in  American  cities  as  one  of  the  kinds  of  building-material. 
The  waves  and  currents  were  then  as  quiet  in  their  work  about  the  Adiron- 
dack shores  as  they  are  now  on  the  New  Jersey  coast.  No  evidence  exists 
that  the  world's  tides  and  currents  had  greater  force  than  in  this  modern  era 
of  a  quiet  earth. 

Climate  in  the  Cambrian.  —  The  evidence  as  to  climate  open  to  the  geolo- 
gist is  that  based  on  the  kinds  of  life  represented  by  fossils  in  the  rocks. 
The  Cambrian  fossils  thus  far  studied  are  from  temperate  latitudes  only. 
Nothing  is  gathered  from  them  as  to  different  zones  of  temperature  in  the 
ocean,  and  nothing  that  proves  the  temperature  of  the  waters  to  have  been 
warmer  than  that  of  the  existing  torrid  and  warm-temperate  zone.  We  have, 
therefore,  to  regard  the  climate,  as  well  as  the  tides  and  waves,  to  have  been 
such  as  now  characterize  the  warmer  portions  of  the  existing  world.  There 
was  no  frigid  zone,  and  there  may  have  been  no  excessively  torrid  zone. 

Purity  of  the  air  and  waters.  —  The  purification  of  the  air  and  waters 
through  the  making  of  limestone,  which  commenced  in  the  later  part  of 
Archaean  time,  continued  through  the  Cambrian ;  for  limestones  are  common 
rocks  in  the  series,  though  far  from  being  the  only  ones.  The  degree  of 


PALEOZOIC   TIME  —  CAMBRIAN.  485 

purity  attained  is  unknown ;  experiments  on  modern  life  may  possibly  lead 
to  some  reasonable  estimate.  This  much  is  certain:  that  the  waters  were 
sufficiently  pure  for  the  development  of  a  great  diversity,  as  has  been  shown, 
of  aquatic  life.  The  types  of  the  early  Cambrian  are  mostly  identical  with 
those  now  represented  in  existing  seas,  and  although  inferior  in  general  as 
to  jvade,  they  bear  no  marks  of  imperfect  or  stunted  growth  from  unfit  or 
foul  surroundings.  How  the  purification  was  made  so  complete  by  the 
beginning  of  Paleozoic  time  has  not  been  explained. 

The  following  observations  have  an  important  bearing  on  this  subject,  although  falling 
short  of  the  needed  explanation  :  — 

If  the  carbonic  acid  in  the  limestones  of  the  world  and  other  carbonates,  and  the  carbon 
of  the  coal  and  carbonaceous  products  in  the  rocks  were  originally,  as  is  believed,  in  the  air 
and  waters,  the  amount  of  these  carbonates  and  carbonaceous  products  in  the  formations 
of  the  Cambrian  and  all  later  periods  would  afford  a  basis  for  estimating  approximately 
the  amount  of  available  carbonic  acid  existing  at  the  beginning  of  these  periods. 

For  the  estimation  there  are  the  following  data.  A  cubic  foot  of  pure  limestone 
which  is  half  calcite  and  half  dolomite,  and  has  the  normal  specific  gravity  2-75,  weighs 
171-4  pounds  ;  and  this,  allowing  for  T^  impurity,  becomes  157  pounds,  and  corresponds 
to  72  pounds  of  carbonic  acid.  A  cubic  foot  is  equal  to  an  inch-square  column  144  feet  in 
height.  Since  72  is  half  of  144,  each  foot  of  the  column  of  such  limestone  contains  half  a 
pound  of  carbonic  acid.  Hence  a  layer  of  the  limestone  1  foot  thick  would  give  to  the 
atn  osphere,  on  decomposition,  half  a  pound  of  carbonic  acid  for  each  square  inch  of 
surface. 

A  foot  layer  of  good  bituminous  coal  containing  80  per  cent  of  carbon,  G  =  1-5,  will 
give  to  the  atmosphere,  by  oxidation,  1-9  pounds  of  carbonic  acid  per  square  inch  of 
surface. 

If  the  mean  thickness  of  the  limestone  over  the  whole  earth's  surface,  that  of  the 
oceans  included,  reckoned  on  a  basis  of  TV  impurity,  is  1000  feet,  the  contained  carbonic 
acid  amounts,  according  to  the  above,  to  500  pounds  per  square  inch,  or  34  atmospheres 
(of  14|  pounds),  and  if  the  mean  thickness  of  the  coal  is  1  foot,  the  carbonic  acid  it 
could  contribute  would  be  1'9  pounds  per  square  inch.  Adding  these  amounts  to  the 
carbonic  acid  corresponding  to  the  carbon  in  the  mineral  oil  and  gas  and  other  carbona- 
ceous products  of  the  rocks  and  organic  life,  supposing  it  to  be  6  times  that  of  the  coal, 
the  total  is  513-5  pounds,  or  35  atmospheres.  The  mean  thickness  of  Archaean  calcium, 
magnesium,  and  iron  carbonate  is  not  a  fourth  of  that  of  post-Archaean.  Estimating  the 
carbonic  acid  they  contain  and  that  corresponding  to  the  graphite  of  the  rocks  at  10 
atmospheres,  the  whole  amount  becomes  45  atmospheres. 

It  has  been  suggested  by  some  writers  that  the  total  amount  of  carbonic  acid  in  the 
early  Archaean  was  equivalent  in  pressure  to  200  atmospheres.  But  this  would  require 
that  the  mean  thickness  of  the  limestone  for  Archaean  and  post- Archaean  time  should 
have  been  nearly  6000  feet. 

Part  of  the  limestone  of  post- Archaean  terranes  was  derived  from  the  wear  and  solu- 
tion of  Archaean  limestones,  iron  carbonate,  etc. ,  and  hence  all  the  35  atmospheres  to  the 
square  inch  were  not  in  the  atmosphere  at  the  commencement  of  the  Paleozoic.  But  if 
we  reduce  the  35  atmospheres,  on  this  account,  to  25  atmospheres,  it  is  still  an  enormous 
amount  beyond  what  ordinary  life,  even  aquatic  life,  will  endure.  Reducing  the  esti- 
mated mean  thickness  for  the  limestone  layer  over  the  globe  from  1000  to  500  feet  would 
make  the  amount  less  by  nearly  one  half.  But  with  all  the  reductions  that  can  be  explained, 
the  excess  is  still  very  large.  It  has  been  proved  by  experiment  that  an  excess  also  of 
oxygen  diminishes  the  deleterious  influence  of  carbonic  acid  on  plants ;  and  that  if  the 


486  HISTORICAL   GEOLOGY. 

amount  of  this  gas  is  made  equal  to  that  of  the  oxygen  in  the  present  atmosphere,  plants 
will  still  thrive.  How  far  this  principle  worked  in  early  times  is  among  the  uncertainties. 
The  idea  has  been  thrown  out  by  T.  Sterry  Hunt  that  carbonic  acid  has  been  received 
by  the  earth,  from  time  to  time,  through  the  fall  or  near  contact  of  meteorites,  since  carbon 
exists  sparingly  in  some  of  these  bodies.  But  it  has  not  found  favor  with  astronomers. 

BIOLOGICAL  PROGRESS. 

Display  of  the  system  of  life  in  the  Cambrian.  —  The  system  of  life,  as 
exemplified  by  Lower  Cambrian  species,  was  essentially  the  existing  system. 
Seven  of  the  grander  divisions  of  animal  life  above  the  grade  of  Rhizopods 
were  represented :  Sponges,  Corals,  Echinoderms,  Worms,  Brachiopods,  Mol- 
lusks,  and  Crustaceans.  And  under  Mollusks  there  were  species  of  Lamel- 
libranchs,  Pteropods  or  related  forms,  and  Gastropods ;  under  Crustaceans, 
Entomostracans  of  two  sections,  —  the  Ostracoids  or  Bivalve  Crustaceans, 
and  Caridoids  or  shrimp-shaped  species, — and  Trilobites.  It  is  true  that 
species  are  represented  only  by  their  hard  parts  —  their  shells  or  skeletons. 
But  the  several  subdivisions  have  species  living  in  the  existing  world,  so 
that  the  nature  of  the  life  and  the  laws  of  structure  and  physiology  of  the 
Cambrian  species  are,  with  few  exceptions,  all  within  man's  range  of  study. 

The  multiplicate  structure  a  common,  low-grade  feature  of  the  Cambrian 
fauna.  —  The  multiplicate  structure  exists  among  living  species.  But  in  the 
early  Paleozoic  it  was  a  prevalent  feature  under  all  the  tribes  that  admitted 
of  it.  The  structure  is  a  fundamental  one  in  the  Worms  of  all  ages,  the 
body  consisting  of  an  indefinite  number  of  body-segments ;  and,  since  succes- 
sional  lines  of  development  led  off  from  their  precursors  to  Trilobites  and 
other  Crustaceans,  it  is  natural  that  Cambrian  species  of  these  classes  should 
be  multiplicate  in  number  of  segments.  The  Protocarids  (page  474)  are 
an  example  among  the  Crustaceans,  as  shown  by  the  number  of  segments 
in  the  abdomen ;  the  modern  Apus  is  a  representative  of  the  Protocarid  struc- 
ture. The  Ostracoids  (Fig.  562)  have  their  limbs  and  segments  concealed  by 
the  shell ;  but  there  is  reason  to  believe  that  these  were  multiplicate,  and  proto- 
types of  the  modern  Limnadia.  The  large  Trilobites  on  pages  473,  476  exem- 
plify the  feature.  Only  the  small  Agnostus  family  (page  476)  fails  of  it,  and 
these  species  probably  fail  because  the  form  represents  an  embryonic  condition. 

Other  low-grade  features  of  Lower  Cambrian  species. — The  Cystoids  are 
the  lowest  of  Echinoderms,  inferior  to  Crinoids. 

Brachiopods  are  (1)  mostly  the  hingeless  or  inarticulate  species  ;  (2) 
small  in  size ;  and  (3),  to  a  great  extent,  if  the  number  of  individuals  of  the 
prevailing  kinds  is  considered,  species  having  a  chitinous  shell :  and  all 
these  characters  are  embryonic  features.  Further,  as  remarked  by  Schu- 
chert,  no  species  having  spines  or  loops  within  the  shell  are  yet  known.  The 
special  embryonic  features  of  Kutorgina,  Obolella,  and  Paterina  have  been 
well  illustrated  by  Beecher;  and,  according  to  this  author,  the  genus  Kutor- 
gina is  probably  the  earliest  representative  of  articulate  Brachiopods. 

The  chitinous  shells  of  the  Brachiopods,  that  make  up  so  large  a  part  of 
the  individuals,  contain  much  calcium  phosphate,  as  shown  by  the  analyses 


PALEOZOIC   TIME  —  CAMBRIAN.  487 

of  T.  S.  Hunt  (page  73),  probably  indicating,  as  has  been  suggested,  the 
presence  of  much  phosphatic  material  in  solution  in  the  seawater. 

The  Lamellibranchs  are  the  lowest  of  Mollusks,  and  the  species  were  very 
small.  The  Gastropods  were  very  small,  and  mostly  of  the  Patella-like 
symmetrical,  non-spiral  species ;  but  with  these  occur  species  of  Platyceras, 
having  a  short  spire,  and  some  of  Pleurotomaria,  a  Paleozoic  genus  of  coiled 
species  that  continue  on  through  later  time. 

The  Crustaceans  are  either  species  of  the  lower  division  of  the  class,  the 
Entomostracans,  or  are  Isopod  in  relations. 

Smallness  of  size  is  not,  however,  a  universal  feature.  The  Pteropods, 
among  Mollusks,  were  much  larger  than  the  modern  species  of  the  tribe. 
The  Trilobites  even  of  the  Lower  Cambrian  comprise  species  as  large  as 
living  Crustaceans.  The  Ostracoids  are  generally  larger  than  those  of  recent 
times. 

The  most  prominent  exception  to  low-grade  features  in  the  fauna  is  that 
of  Trilobites,  which  have  nearly  the  perfection  that  belongs  to  the  typical 
Isopod.  Their  primitive  character  is,  however,  marked  in  the  multiplicate 
structure  of  the  thorax  and  its  limbs,  and  in  the  fact,  observed  by  Beecher, 
that  each  of  the  thoracic  legs  has  a  natatory  appendage. 

Embryonic  precursor  lines  fail.  —  The  Lower  Cambrian  species  have 
not  the  simplicity  of  structure  that  would  naturally  be  looked  for  in  the 
earliest  Paleozoic  life.  They  are  perfect  of  their  kind  and  highly  specialized 
structures.  No  steps  from  simple  kinds  leading  up  to  them  have  been  dis- 
covered ;  no  line  from  Protozoans  up  to  Corals,  Echinoderms,  or  Worms,  or 
from  either  of  these  groups  up  to  Brachiopods,  Mollusks,  Trilobites,  or  other 
Crustaceans.  This  appearance  of  abruptness  in  the  introduction  of  Cambrian 
life  is  one  of  the  striking  facts  made  known  by  geology.  But,  as  is  often 
urged,  this  appearance  of  abruptness  is  believed  to  be  due  to  defective  records. 
In  some  regions  there  are  thick  strata  in  the  Cambrian  below  the  lowest  fossi- 
liferous  beds  representing  a  long  lapse  of  time,  besides  others  in  the  Archaean, 
of  whose  life  nothing  is  yet  known.  Again,  species  without  shells  or  stony 
secretions  make  no  fossils,  and  can  leave  no  record;  and  it  is  for  this  reason 
that  we  know  so  little  of  Cambrian  Worms,  all  that  remains  being  the  holes 
or  tracks  they  made. 

Further  :  the  Lower  Cambrian  rocks  are  often  hard  slates  and  grits,  and 
the  heat,  or  heated  moisture,  or  siliceous  solutions,  that  hardened  them  would 
have  tended  to  dissolve  away  calcareous  shells.  The  shells  of  phosphatic 
kinds,  as  the  Lingulse,  Discinse,  and  the  tests  of  Trilobites,  would  have 
suffered  least.  From  this  last  fact  it  follows  that  resistance  to  solution,  not 
predominance  in  number,  may,  in  many  cases,  have  determined  the  relative 
proportions  of  the  species  of  fossils.  These  are  sources  of  uncertainty 
demanding  consideration. 

The  Olenellus  beds  have  been  made  the  Lower  Cambrian.  But  they  are 
not  necessarily  the  lowest.  For  if  strata  should  be  found  containing  no 
Trilobites,  but  only  Worms,  the  lower  types  of  Brachiopods,  Ostracoids  among 


488  HISTORICAL   GEOLOGY. 

Crustaceans,  and  other  inferior  species,  a  place  in  the  Cambrian  would  prop- 
erly be  made  for  it,  unless  the  beds  were  proved  to  be  Huronian  by  evidence 
that  they  had  been  formed  before  the  epoch  of  mountain-making  which  closed 
Archaean  time.  Mere  divergence  to  this  extent  from  the  Lower  Cambrian 
in  life  would  not  be  sufficient  to  require  separation  from  it. 

Progress  through  the  appearance  and  disappearance  of  species.  —  This 
feature  in  the  world's  biological  progress  is  well  illustrated  in  Walcott's 
reports.  Of  the  many  species  of  Trilobites  from  the  Lower  Cambrian,  very 
few  are  known  to  occur  in  the  Middle  Cambrian ;  and.  few  of  those  of  the 
Middle,  in  the  Upper.  According  to  the  facts  thus  far  gathered,  it  may 
seem  that  events  passed' with  a  rush;  that  exterminations  and  renewals 
followed  one  another  at  short  intervals.  But  the  thickness  of  the  rocks 
proves  that  the  three  divisions  of  the  period  were  immensely  long.  There 
may  have  been  many  successive  faunas  in  each.  It  is  quite  certain,  judging 
from  the  teachings  of  the  geological  past,  that  the  abrupt  breaks  are  gener- 
ally, if  not  always,  breaks  in  the  record,  not  breaks  in  the  succession  of 
species. 

The  total  number  of  ascertained  species  from  the  American  Lower  Cam- 
brian is  stated  to  be  less  than  200.  The  number  200,  though  large,  con- 
sidering the  remoteness  of  the  period,  is  very  small  compared  with  that  of 
the  marine  invertebrates  of  existing  American  seas.  There  are  reasons  for 
its  being  so  small ;  for  (1)  only  a  small  part  of  the  rocks  has  been  examined ; 
(2)  hardly  a  tenth  of  the  deposits  made  in  the  Lower  Cambrian  would  have 
escaped  the  destroying  action  of  denuding  agencies;  and  (3),  in  any  case, 
only  a  small  part  of  any  fauna  is  likely  to  become  fossilized.  The  num- 
ber of  species  known  from  the  Middle  Cambrian  is  much  smaller  than 
that  from  the  Lower.  This  is  not  evidence  of  fewer  species  at  one  time  than 
another  in  the  fauna  of  the  world.  It  may  be  proof  that  the  conditions  were 
unfavorable  over  the  regions  geologically  studied  for  the  preservation  of 
their  remains.  These  unfavorable  conditions  may  have  been  due  to  tem- 
porary changes  of  water  level  that  made  densely  brackish  seas  over  large 
parts  of  the  continental  surface,  or  as  great  fresh-water  seas ;  or  to  other 
local  circumstances  not  now  discoverable.  The  absence  of  Lamellibranchs 
in  the  Middle  Cambrian,  although  present  in  both  the  Lower  and  Upper, 
means  the  absence  of  fossils  from  the  rocks,  not  of  species  from  the  faunas. 

Progress  in  Cambrian  life  after  the  Lower  Cambrian.  —  This  progress 
is  strongly  marked.  In  the  Upper  Cambrian,  Brachiopods  are  of  more  genera ; 
Conularia  is  added  to  the  Pteropods ;  Gastropods  are  of  normal  size,  and 
those  with  spiral  shells  are  multiplied ;  and  Crustaceans  are  advanced  to  the 
grade  of  non-multiplicate  Hymenocarids  ;  and  before  the  epoch  ended  there 
were  true  Crinoids  and  Star-fishes  in  the  seas ;  Trilobites  had  appeared  of 
the  genus  Asaphus ;  Ceratiocarid  Crustaceans  were  in  the  waters ;  and  be- 
sides these,  Cephalopods,  the  higher  Mollusks,  were  represented  by  species 
of  Orthoceras  and  Cyrtoceras,  the  straight  form  of  Orthoceras  apparently 
preceding  the  curved  form  of  Cyrtoceras. 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


489 


LOWER  SILURIAN  ERA. 

SYNONYMY.  —  Lower  Silurian,  Murchison,  Phil.  Mag.,  vii.  46,  1835;  Brit.  Assoc.,  v., 
1835.  Lower  Silurian,  Upper  Cambrian,  Sedgwick,  but  not  aware  of  their  identity,  Brit. 
Assoc.,  v.,  1835.  Lower  Silurian,  including  the  Lingula  flags,  Murchison,  Sil.  Syst.,  1838  ; 
Geikie,  in  3d  edit,  of  Jukes's  Geol.,  1872  ;  Dana's  Manual  of  Geol.,  1874.  Lower  Silurian, 
Lyell,  Elements  Geol.,  2d  edit.,  1841,  and  later ;  Geikie,  Text-book  Geol.,  1885 ;  Seeley 
and  Etheridge,  Man.  Geol.,  1885;  Prestwich,  Geol.,  1886 ;  Credner,  Geol.,  1887.  Cambro- 
Silurian,  Jukes,  Canadian  Geological  Survey.  Fauna  D,  or  Second  Fauna,  Barrande. 
Silurienne,Etage  Armoricain,  Lapparent,  Tr.  Geol.,  1883. 

Champlain  group,  but  with  the  Potsdam  sandstone  and  the  Oneida  conglomerate  in- 
cluded, Hall,  Hep.  N.  Y.  G.  Surv.,  1843  ;  same,  with  the  Oneida  conglomerate  excluded, 
Mather,  Vanuxem,  Emmons,  Hep.  N.  Y.  G.  Surv.,  1842,  1843. 

Ordovician,  Lapworth  (from  the  name  of  the  British  tribe,  Ordovices),  G.  Mag.,  1879, 
p.  13.  Upper  Cambrian,  Ordovician,  H.  B.  Woodward,  Geol.  of  Eng.  and  Wales,  1887. 

The  counter-claims  of  Sedgwick  and  Murchison  with  reference  to  the 
geological  formations  in  which  they  both  had  worked,  appeared  to  have 
been  settled  by  the  recognition  of  a  Cambrian  system  below  the  Lower 
Silurian.  But  the  independent  characteristics  of  the  Lower  and  Upper 
Silurian  becoming  increasingly  evident,  it  has  seemed  to  demand  that  the 
two  eras  should  have  independent  names.  Notwithstanding  the  great 
claims  of  Murchison,  the  new  name  of  Ordovician,  proposed  in  1879  by 
Lapworth,  is  much  used  for  the  Lower  Silurian,  the  one  which  represents 
the  larger  share  of  Murchison's  labors,  and  thereby  the  old  Murchisonian 
name  of  Silurian  is  left  for  the  Upper  division.  As  this  is  not  the  disposal 
of  the  question  which  the  law  of  priority  appears  to  require,  the  name  of 
Lower  Silurian  is  here  retained,  awaiting  the  full  expression  of  geological 
opinion. 

NORTH  AMERICAN. 

SUBDIVISIONS. 

3.  HUDSON  EPOCH  :   that   of    the   Hudson   slate   group   or 
Hudson  River  group,  Mather,  Ann.  Rep.   Geol.  N.  Y.,  1840 ; 
Hudson   River   group,    Mather,   Hall,    Vanuxem,    Final  Rep. 
GeoL  N.  Y.,  1842,  1843 ;  Lorraine  shales,  Emmons,  Final  Rep. 
N.  Y.,  1843 ;  Nashville  group,  of  Tennessee,  J.  M.  Safford,  Am. 
2.  Trenton    I  Jour.  ScL,  xii.,  1851;  Cincinnati  group,  Worthen,  Rep.  Geol. 
Period.      I   III,  L,  1866. 

2.  UTICA  EPOCH  :  that  of  the  Utica  slate,  N.  Y.  Geol.  Rep., 
1842,  1843 ;  Black  slate,  Ann.  N.  Y.  Rep. 

1.  TRENTON  EPOCH  :  that  of  the  Trenton,  Birdseye,  and  Black 
River  limestones,  Vanuxem,   Conrad,  Ann.  Rep.   Geol.  N.  Y., 
I  1838. 


490  HISTORICAL   GEOLOGY. 


1.  Canadian 
Period. 


2.  CHAZY  EPOCH  :  that  of  the  Chazy  limestone,  Emmons. 
Final  Rep.  Geol.  N.  Y.,  1843. 

1.  CALCIFEROUS  EPOCH  :  that  of  the  Calciferous  sandrock  of 
Amos  Eaton,  Geol.  and  Agric.  /Survey  distr.  adj.  Erie  Canal, 
N.Y.,  under  S.  Van  Eensselaer,  1824.  Part  of  the  Levis,  of 
Logan's  Quebec  group. 


In  the  Keports  of  the  first  Pennsylvania  Geological  Survey,  Professor  H.  D.  Rogers 
uses  the  following  terms  and  numbers:  Primal,  L,  for  Cambrian  ;  Auroral,  II.,  for  the 
Calciferous  and  Chazy  ;  Matinal,  III.,  for  the  Trenton.  The  Taconic  series  of  Emmons, 
along  western  New  England  and  eastern  New  York,  corresponds  to  the  Cambrian  and 
Lower  Silurian  formations  combined.  The  geologists  of  the  New  York  Geological  Survey 
of  1836  to  1842  were  Ebenezer  Emmons,  W.  W.  Mather,  James  Hall,  Lardner  Vanuxem, 
and  T.  A.  Conrad,  the  last  acting  as  paleontologist.  After  the  close  of  the  general  survey 
of  the  State,  Hall  was  given  charge  of  the  paleontology. 

ROCKS  — KINDS  AND  DISTRIBUTION. 

The  Lower  Silurian  formations  are  to  a  large  extent  limestone ;  they  are 
partly  calcyte,  but  more  widely  dolomyte.  Arenaceous  and  shaly  strata 
are  most  common  in  the  earlier  and  later  part  of  the  series,  that  is,  in  the 
Calciferous  epoch  and  the  Hudson  epoch ;  but  in  the  Interior  Continental 
region  the  larger  part  of  the  rocks  of  these  earliest  and  latest  divisions  is 
calcareous.  The  Trenton  rocks  are  remarkable  for  their  wide  distribution 
over  the  continent.  Outside  of  the  Archseo-Cambrian  areas  they  extend  for 
the  most  part  from  the  Atlantic  to  the  Pacific,  though  covered  in  general  by 
later  rocks.  The  larger  part  of  the  outcrops  of  the  limestones  follows  the 
outline  of  the  Archaean  areas,  separated  from  them,  if  at  all,  only  by  out- 
cropping belts  of  Cambrian,  showing  that  the,  shore  line  in  the  Lower 
Silurian  era  was  not  far  distant  from  its  Cambrian  position. 

This  is  true  around  the  Adirondack  area  in  New  York,  and  from  central 
New  York  westward  to  Wisconsin  and  Minnesota.  It  is  also  true  along  the 
Appalachian  protaxis  from  Canada  and  the  Green  Mountain  region  to  Ala- 
bama, on  both  its  east  and  west  sides ;  also  in  the  Ottawa  region,  Canada, 
where  there  was  a  large  Lower  Silurian  basin  as  successor  to  that  of  the 
Cambrian  era ;  also  along  the  St.  Lawrence  northeastward,  along  the  western 
arm  of  the  Archaean  V  northwestward,  and  on  some  Arctic  islands.  It  was 
true,  also,  along  portions  of  the  Kocky  Mountain  protaxis ;  but  here,  owing 
to  the  thickness  of  the  later  formations,  the  Lower  Silurian  beds  are  not 
commonly  at  the  surface.  Some  of  the  deep  canons  of  the  Pacific  Border 
region  cut  down  to  them  through  1000  to  3000  feet  of  overlying  beds. 

In  the  Continental  Interior  two  isolated  areas  lie  in  a  line,  one  over 
southern  Ohio,  part  of  Kentucky,  and  the  border  of  Indiana ;  and  the  other 
in  Tennessee  (C,  T,  on  the  map,  page  536).  The  region  is  that  of  the 
so-called  "  Cincinnati  uplift,"  or  anticline. 

On  the  borders  of  western  New  England  and  eastern  New  York,  along 
the  Taconic  Range  and  either  side  of  it,  the  crystalline  schists  and  limestone 


PALEOZOIC   TIME  —  LOWER   SILURIAN.  491 

are  largely  Lower  Silurian  and  Cambrian.  They  are  the  Taconic  series  of 
Emmons.  The  Eolian  limestone  of  Vermont,  and  its  continuation,  the 
Stockbridge,  of  Berkshire,  Mass.,  with  the  intervening  ridges  of  slates  and 
schists,  are  of  this  series,  and  also,  the  extension  of  the  lines  southward, 
though  interruptedly,  into  New  Jersey  and  Pennsylvania ;  and  it  probably 
comprises  the  interrupted  series  of  limestone  belts  and  the  associated 
schists  which  extend  from  Canaan,  Conn.,  south  through  Litch field  County, 
Conn.,  and  Westchester  County,  N.Y.,  to  New  York  or  Manhattan  Island, 
and  part  of  this  island,  the  rest  being  probably  Archaean. 

1.  CANADIAN  PERIOD. 

1.  Calciferous  Epoch.  —  The  Calciferous  formation,  along  the  borders  of 
the  Archaean  of  northern  New  York  and  Canada,  consists  of  a  grayish  lime- 
stone which  is  often  arenaceous  and  cherty,  usually  magnesian,  and  rarely 
fossiliferous.     It  then  extends  southwestward  through  New  Jersey  and  east- 
ern Pennsylvania.     It  includes  in  Missouri  the  first  or  upper  of  the  four 
Lower  Magnesian  limestones,  with  the  underlying  sandstone  called  the  first, 
or  Saccharoidal  sandstone.     Its  equivalent  is  the  "Lower  Magnegian"  of 
Iowa  and  Minnesota. 

2.  Chazy  Epoch.  —  The  Chazy  beds  in  New  York  consist  mostly  of  lime- 
stone.    The  formation  was  so  named  by  E.  Emmons,  after  the  village  Chazy, 
in  Clinton  County,  N. Y.,  where  the  formation  has  a  thickness  of  730  feet.     The 
limestone  is  gray  to  black  in  color,  and  is  often  recognizable,  when  in  polished 
slabs  of  black  marble,  by  the  presence  of  a  large  fossil  shell  three  inches  or 
more  across — the  Maclurea  magna  (Fig.  634).     The  limestone  is  mostly 
dolomyte.     It  occurs  in  Canada  about  the  Ottawa  basin.     On  the  eastern 
border  of  New  York  and  the  western  of  New  England  it  makes  part  of  the 
Taconic  series.      The  St.  Peter's  sandstone  of  the  northern  part  of  the 
Mississippi  valley  has  been  referred  to  the  Chazy  epoch;  but  it  contains 
few  fossils  of  any  kind,  and  none  are  characteristically  Chazy. 

2.  TRENTON  PERIOD. 

The  Trenton  period  is  represented  in  New  York,  in  its  earlier  part,  by 
limestones,  and  in  its  later  part  by  shales  ;  and  this  division  in  the  rocks  is  the 
basis  of  a  subdivision  of  the  period  into  the  Trenton  and  Utica  and  Hudson 
epochs.  This  succession  in  the  rocks  implies  that  a  time  of  clear  open  seas 
first  existed,  in  which  Trilobites,  Gastropods,  and  Bryozoans  abounded,  as 
well  as  Brachiopods ;  but  that  later,  through  some  unexplained  topographical 
change,  the  waters  lost  much  of  their  clearness,  and  bore  along  so  much 
sediment  that  mud  deposits  were  made  over  the  bottom,  extinguishing  life 
that  could  not  adapt  itself  to  the  new  conditions,  reducing  Trilobites  to  a 
few  species,  favoring  the  multiplication  of  Lamellibranchs  and  other  Mol- 
lusks,  and  causing  many  other  changes  both  by  migration  and  modification. 
The  change,  moreover,  was  one  of  wide  extent  and  influence. 

The  name  Trenton  is  derived  from  Trenton  Falls,  north  of  Utica,  in 


492  HISTORICAL   GEOLOGY. 

Oneida  County,  N.Y.,  where  the  limestone  stands  in  bold  bluffs  along  the 
wild  canon  of  West  Canada  Creek,  and  affords  a  good  place  for  the  study  of 
the  rock  and  its  fossils. 

1 .  Trenton  Epoch.  —  In  the  region  of  Trenton  Falls  the  limestone  is  a 
blackish  to  dark  gray  thin-bedded  rock,  owing  its  color,  like  the  Utica  shale, 
to   carbonaceous  or   bituminous   material.     The  lower  part  of  the  Trenton 
formation  is  called  the  Black  River  limestone,  from  Black  River  ;  it  outcrops 
to  the  north  of  Trenton   Falls,  and,  like   the  Trenton,  it  is  widely  distri- 
buted over  the  country.     A  stratum,  30  feet  or  less  thick,  at  the  bottom  of 
this  limestone  in  central  New  York,  is  the  Birdseye  limestone  —  a  gray,  dove- 
colored  rock,  speckled  with  white  crystalline  points,  that  are  due  in  part  at 
least  to  the  presence  of  a  fossil   coral  and  its  crystallization  into  calcite. 
The  Kentucky  Chazy  limestone  contains  similar  "  birdseyes,"  and  has  great 
thickness.     The  Trenton  in  Wisconsin,  Illinois,  and  Iowa  is  a  bluish  gray  to 
buff-colored  rock.   Above  it  lies  the  "  Galena  limestone,"  about  250  feet  thick, 
mostly  dolomyte,  which  is  noted  for  its  deposits  of  lead  ore ;  it  corresponds 
to  the  later  part  of  the  Trenton  epoch. 

2.  Utica  and  Hudson  Epochs.  —  The  shales  of  the  Utica  epoch  outcrop 
along  a  narrow  region  in  the  Mohawk  valley,  east  and  west  of  Utica,  the 
place  after  which  they  are  named;  and  those  of  the  later  Hudson  epoch, 
along  the  south  side  of  the  Utica  shales.     They  also  extend  down  the  Hudson 
River  valley  (whence  the  name)  to  Fishkill ;  but  part  of  the  shales  formerly 
called  Hudson  Eiver  shales  have  proved  to  be  Cambrian. 

The  Hudson  shales  have  their  greatest  thickness  in  eastern  New  York. 
A  boring  15  miles  west  of  Albany  passed  through  3440  feet  of  shales,  partly 
the  Utica  shales,  into  the  Trenton  limestone.  In  central  New  York,  20  miles 
west  of  Oneida  Lake,  a  boring  went  through  1000  feet  of  Hudson  and  Utica 
shales,  and  at  Utica,  through  800  feet  of  the  two.  The  impure  limestone  and 
shales  of  the  region  about  Cincinnati  are  of  the  Hudson  epoch.  The  thick- 
ness at  Cincinnati  is  about  750  feet.  The  lower  part  of  the  series  contains 
fossils  of  the  Utica  shale  of  New  York,  mingled  with  other  species  belonging 
to  the  Trenton  or  the  Hudson  rocks  of  New  York.  In  Ohio  and  Kentucky 
the  Cincinnati  beds  overlie  600  or  700  feet  of  limestones  and  shales  which 
are  mainly  of  the  Trenton  epoch. 

1.  CANADIAN  PERIOD. 
1.  Calciferous  Epoch. 

a.  Eastern  Border  region.  —  In  noi  thwestern  Newfoundland,  on  the  Straits  of  Belle 
Isle,  Upper  Calciferous  is  stated  to  include  2061'  of  limestone.     Below  these  are  the  Lower 
Calciferous  of  the  age  of  the  New  York  beds  (Billings,  Logan).     The  beds  continue  down 
the  coast  of  Newfoundland  to  Bonne  Bay  and  beyond.     The  Calciferous  is  250'  thick  at 
the  Mingan  Islands,  and  continues  from  there  to  St.  Genevieve,  on  the  Lower  St.  Lawrence. 

b.  Appalachian  and  Interior  Continental  regions.  —  In  some  places  in  New  York  the 
layers  of  the  Calciferous  are  hard  and  siliceous,  and  contain  geodes  of  quartz  crystals,  as 
at  Diamond  Rock,  Lake  George,  and  at  Middleville  and  elsewhere  in  Herkimer  County, 


PALEOZOIC   TIME LOWER   SILURIAN.  493 

etc.,  where  the  Archaean  has  outcrops  not  far  distant  (at  Little  Falls).  A  cavity  is  re- 
ported to  have  contained  half  a  bushel  of  loose,  transparent  crystals.  Fragments  and 
nodules  of  anthracite  coal  are  sometimes  included  in  the  crystals  or  accompany  the  crystals 
in  the  cavity  ;  the  larger  nodules  are  two  inches  or  more  long.  Besides  quartz  and  calcite, 
barite,  celestite,  gypsum,  and  occasionally  blende  are  found  in  its  cavities. 

In  Canada,  north  of  New  York,  the  Calciferous  beds  spread  widely  over  the  western 
part  of  the  Ottawa  basin,  and  in  general  are  nearly  pure  dolomyte,  but  with  cherty  or 
sandy  layers.  The  fossils  are  mostly  weathered  out.  Thickness,  50'  to  300'.  In  Ten- 
nessee, the  Knox  dolomyte,  above  its  lower  2000'  of  Upper  Cambrian,  contains  typical 
Calciferous  fossils.  In  Missouri,  the  first  magnesian  limestone,  which  has  been  ascer- 
tained by  fossils  to  be  Calciferous,  has  a  thickness  of  50'  to  150'.  The  Saccharoidal  sand- 
stone, 100'  to  133'  thick,  is  very  white,  and  is  used  for  glass-making. 

"  Lower  magnesian  limestone  "  of  Iowa,  Minnesota,  and  Wisconsin,  has  been  found 
to  contain  Calciferous  fossils  in  Clayton  and  Allamaker  Counties,  according  to  S.  Calvin. 

2.  Chazy  Epoch. 

At  Chazy,  according  to  Brainard  and  Seely,  the  Chazy  limestone  has  three  divisions : 
a  lower  of  310' ;  a  middle  of  265',  thick-bedded  and  abounding  in  Maclurea ;  and  an  upper 
of  157',  which  is  very  various  in  character,  partly  siliceous  dolomyte.  The  middle  di- 
vision contains  a  20-foot  bed  of  pure  gray  limestone  which  is  often  oolitic  ;  it  is  50  feet 
above  the  bottom,  and  is  free  from  the  Maclurea,  —  a  fact  accounted  for  by  the  oolitic 
character,  since  this  structure  is  produced  only  in  tide-washed  calcareous  sand-flats  or 
beaches.  It  makes  a  handsome  marble  called  "French  Gray,"  while  the  Maclurea  beds 
make  a  black  or  grayish  black  marble. 

The  Chazy  beds  thin  out  in  the  valley  of  the  Mohawk,  where  the  Calciferous  is  often 
followed  directly  by  the  Birdseye. 

The  Chazy  is  the  Grenville  limestone  of  the  Ottawa  region ;  it  is  largely  developed 
about  Montreal.  It  often  contains  the  shells  of  Lingulse  in  phosphatic  concretions ;  and 
shells  of  Pleurotomaria  occur  as  casts  of  calcium  phosphate.  The  beds  are  300'  thick  at 
the  Mingan  Islands.  No  characteristic  Chazy  fossils  have  been  reported  from  the  Missis- 
sippi valley.  The  St.  Peter's  sandstone  of  Iowa,  Minnesota,  and  the  adjoining  part  of 
Wisconsin  underlies  the  Trenton,  and  has  been  referred  to  the  Chazy.  It  has  been  re- 
ported as  affording  a  few  fossils  related  to  those  of  the  lower  part  of  the  Trenton.  But 
in  Iowa  and  Minnesota  the  name  covers  limestone  beds  as  well  as  those  of  sandstone. 
The  limestones  become  thicker  in  the  latter  State,  and  constitute  the  Shakopee  limestone, 
which  is  the  middle  member  of  the  sandstone.  In  Iowa  the  St.  Peter's  sandstone  includes 
also  the  Willow  River  limestone,  and  in  Wisconsin  the  New  Richmond  sandstone.  A 
sandstone  has  been  met  with,  also,  in  borings  in  Indiana,  below  the  Trenton,  and  over  507 
of  magnesian  limestone,  which  is  supposed  to  be  the  St.  Peter's.  The  thickness  is  150'  to 
224' ;  its  waters  are  often  saline. 

2.  TRENTON  PERIOD. 

a.  Eastern  Border  region.  —  The  Hudson  beds  of  Anticosti,  along  its  north  side,  are 
of  limestone,  and  959'  thick.  Above  these  are  limestone  beds  of  the  Upper  Silurian,  in  all 
about  1400'.  The  rocks  are  nearly  horizontal.  The  Trenton  occurs  in  central  and  west- 
ern New  Brunswick,  but  on  the  coast  and  along  the  shores  of  Maine  only  doubtfully  at 
Foster  Island  near  Machiasport. 

6.  Appalachian  and  Interior  Continental  regions.  — The  Trenton  limestone  in  central 
New  York  extends  as  a  surface  rock  through  Oneida  and  Lewis  counties  to  Lake  Ontario  ; 
then  reappears  across  the  lake  and  stretches  westward  in  a  band  30  miles  wide  to  Georgian 
Bay.  It  occurs  also  on  the  Manitoulin  Islands  and  Drummond's  Island,  Lake  Huron.  The 
thickness  at  Montreal  is  600',  in  the  Ottawa  basin  as  great,  and  nearly  1000'  west  of 


494  HISTORICAL   GEOLOGY. 

Lake  Ontario.  East  of  the  Hudson  it  occurs  over  large  areas  as  part  of  the  Taconic 
series  described  beyond.  In  the  west-central  portion  of  southern  New  York  it  is  covered 
to  a  depth  of  2000'  or  more  by  later  formations. 

The  Utica  shale  is  15'  to  35'  thick  at  Glen's  Falls,  in  New  York  j  250'  in  Montgomery 
County  ;  300'  in  Lewis  County. 

The  Hudson  Kiver  shales  cover  the  region  north  of  Lake  Champlain,  in  Canada, 
reaching  to  Quebec,  and  northeastward  to  Montmorency  and  beyond.  They  also  cover 
a  small  area  near  the  center  of  the  Trenton  limestone  region  of  the  Ottawa  basin.  In  New 
York  they  include  shales  and  sandstones.  They  are  the  Lorraine  shales  of  Jefferson 
County  (the  Pulaski  shales  of  the  New  York  Annual  Reports),  containing  some  thin  beds 
of  limestone.  The  thickness  of  the  shales,  in  Schoharie  County,  N.Y.,  is  700' ;  in  western 
Canada,  700' ;  in  a  boring  at  Utica,  N.Y.,  90',  below  710'  of  Utica  shale: 

In  Pennsylvania  the  Hudson  shales  (Matinal  of  Rogers,  or  his  No.  Ill)  border  the 
Trenton  areas,  and  have  in  general  great  thickness. 

In  Ohio  the  Trenton,  in  the  Cincinnati  region,  lies  beneath  700'  or  so  of  beds  of  impure 
thin-bedded  limestone  and  shale  of  the  Hudson  (Cincinnati)  epoch ;  and  to  the  north  these 
shales  are  500'  to  1000'  thick,  and  include  at  base  300'  of  Utica  shales.  The  same  beds 
are  continued  westward  into  Indiana,  in  the  eastern  part  of  which  State  the  thickness  is 
about  1650'.  Of  this,  500'  to  600'  are  Trenton  and  Galena  limestone  ;  it  is  usually  of  gray 
to  buff  and  white  color,  but  in  the  northwestern  part  of  the  state,  chocolate-brown. 

South  of  the  Ohio,  in  middle  Kentucky,  the  Trenton,  which  includes  the  "Blue  lime- 
stone" of  Owen,  is  well  represented  by  thick-bedded  limestone,  with  some  shaly  seams; 
the  beds  have  a  small  northward  dip,  toward  the  Cincinnati  region  and  Lake  Erie,  along 
the  area  of  the  "  Cincinnati  anticline." 

In  the  valley  of  east  Tennessee,  the  Trenton  includes  the  "Blue  or  Maclurea  limestone  " 
of  Safford,  and  is  200'  to  600'  thick  ;  and  above  this  comes  the  "  Nashville  shale  "  of  the 
Hudson  epoch,  which  is  partly  calcareous  (becoming  increasingly  so  to  the  westward)  and 
is  about  2000'  thick.  In  the  Maclurea  limestone  occurs,  as  an  interpolated  bed,  the  clouded 
red  limestone,  affording  the  famous  Tennessee  marble  ;  it  is  about  380'  thick.  In  middle 
Tennessee  the  Trenton  and  Nashville  strata  are  horizontal,  and  all  is  limestone,  the  later 
less  pure  ;  thickness  about  45Q'.  (Safford.) 

The  Galena  or  lead-bearing  limestone,  of  Wisconsin  and  the  adjoining  States  in  the 
West,  is  100'  to  200'  thick  in  northern  Illinois  and  about  250'  thick  near  Dubuque,  Iowa; 
and  the  underlying  Trenton  20'  to  100'. 

In  Wisconsin  and  the  adjoining  part  of  Minnesota  the  Trenton  limestone  is  300'  to 
350'  thick  ;  the  lower  thinner  part  represents  the  Birdseye  and  Black  River  limestones  of 
New  York.  The  upper  part  is  the  Galena  limestone.  Although  mostly  a  dolomyte,  it 
is  not  all  so  ;  in  some  parts  of  the  lead  region  only  the  lower  18'  to  25',  called  the  Buff 
limestone,  out  of  a  thickness  of  100'  or  more,  is  magnesian.  The  Buff  limestone  from  the 
southern  part  of  the  town  of  Bristol  afforded  calcium  carbonate  56-07  to  magnesium  car- 
bonate 35-32.  An  associated  blue  limestone  afforded  84-02  of  the  former  to  5-33  of  the 
latter  ;  the  rock  of  another  bed,  97-92  of  the  former  to  1-00  of  the  latter.  (J.  D.  Whitney, 
T.  C.  Chamberlin.) 

In  Iowa,  at  Washington,  a  boring  struck  Hudson  shales  at  700',  the  Galena  limestone 
at  800',  the  Trenton  at  1020',  and  St.  Peter's  sandstone  at  1100'  j  and  below  this,  at  1230', 
the  magnesian  limestone. 

In  Minnesota,  the  Trenton,  as  it  occurs  near  Minneapolis,  consists  of  dolomitic  lime- 
stone, more  or  less  argillaceous,  of  a  buff  to  a  drab  color,  with  intercalated  shaly  portions 
and  blue  shale  at  base.  The  thickness  in  the  State  is  15'  to  70'.  The  Trenton  in  Missouri, 
according  to  Broadhead,  has  a  probable  thickness  of  400'. 

c.  In  the  Pocky  Mountain  region. — The  Calciferous  period  is  represented  probably  by 
the  Ute  limestone  in  the  Wasatch,  1000'  to  2000'  thick ;  it  includes  beds  in  the  House 


PALEOZOIC   TIME  —  LOWER    SILURIAN.  495 

Range,  Utah,  and  the  lower  part  of  the  Pogonip  limestone,  in  the  White  Pine  and  Eureka 
districts. 

To  the  Trenton  period  are  referred  limestone  beds  at  the  Big  Cottonwood  Canon, 
over  the  Cambrian,  part  of  the  Pogonip  limestone  ;  Prospect  Ridge,  Fish  Creek  Mountain, 
etc.,  in  the  Eureka  district,  Nevada,  and  later  Trenton  limestone  (Hudson  epoch?)  in 
Lone  Mountain,  with  500'  of  quartzyte  between  the  two  (Hague,  Walcott) ;  beds  at  Silver 
City  and  Upper  Mimbres  Mining  Camp,  New  Mexico,  referred -to  Hudson  epoch  ;  in  South 
Park,  Arkansas  Canon,  etc.  (Stevenson,  Wheeler  Exp.,  1876);  in  British  America,  grap- 
tolitic  Utica  shales  in  the  Kicking  Horse  Pass  (Can.  Rep.,  1886). 

In  the  Trenton,  near  Canon  City,  Colorado,  occurs  the  Harding  sandstone,  in  which 
Walcott  discovered,  in  1890,  the  plates  of  Placodenn  Fishes,  described  on  page  510. 
Walcott  gives  the  following  section  of  the  rocks  :  At  the  base  is  a  reddish  gneiss.  This 
is  followed  by  22 1'  of  reddish  arenaceous  limestone  with  thin  interbedded  layers  of  chert, 
carrying  fossils  of  Upper  Cambrian  type.  Above  this  limestone  lie  51'  of  pinkish  arena- 
ceous limestone,  carrying  Ophileta,  Straparollus,  etc.,  characteristic  of  the  base  of  the 
Lower  Silurian,  or  the  Calciferous  fauna  of  New  York  ;  over  this  a  series  of  sandstones 
(Harding  sandstone)  101'  thick,  in  which  occur,  along  with  an  abundant  invertebrate 
fauna,  the  plates  of  the  Placoderm  Fishes.-  A  massive  bedded,  gray,  arenaceous  limestone 
succeeds  the  sandstone  with  a  thickness  of  110',  and  this  is  followed  by  a  thin  band  of 
Carboniferous  limestone. 

d.  Arctic  region.  —  Lower  Silurian  beds  have  been  identified  on  North  Devon,  Corn- 
wallis,  Griffith,  west  coast  of  King  William  Land,  Boothia,  in  Frobisher  Bay,  from  Hall's 
collections,  on  the  shores  of  Kennedy  Channel.  (For  a  review  of  the  facts  respecting 
Arctic  geology  and  a  geological  map,  see  G.  M.  Dawson's  paper,  Can.  Hep.  for  1886.) 

The  Taconic  system  of  Emmons. — The  Taconic  system  was  first  announced  by 
Emmons  in  1842,  in  his  N.  Y.  Geological  Report  of  that  year,  and  pronounced  pre-Potsdam 
on  the  general  ground  of  the  kinds  of  rocks  and  the  assumed  absence  of  fossils.  In  1844, 
fossils  having  become  known  to  him  from  beds  at  Bald  Mountain,  in  Washington  County, 
N.Y.,  that  had  been  included  by  him  within  the  Taconic,  he  divided  the  Taconic  series 
into  the  Upper  Taconic,  or  that  containing  fossils,  and  the  Lower  Taconic.  Later  dis- 
coveries proved  that  his  Upper  Taconic  rocks  were  really  the  oldest.  The  rocks  of  the 
so-called  Lower  Taconic  were  quartzyte,  limestone,  and  schists  in  several  belts,  —  situated 
along  and  near  the  Taconic  range  on  the  western  boundary  of  New  England,  in  Berkshire 
and  eastern  New  York,  and  thence  extending  northward  and  southward,  and  also  west- 
ward to  the  Hudson  River.  Although  the  "Lower  Taconic"  rocks  are  metamorphic, 
and  coarsely  so  in  Berkshire,  they  were  afterward  found  at  many  points  to  contain  fossils, 
and  are  now  known  to  be  mainly  of  Cambrian  and  Low^r  Silurian  age. 

These  discoveries  were  made  as  follows,  and  chiefly  in  the  limestone  :  1857  to  1861, 
Vermont  survey,  under  C.  H.  Hitchcock  and  A.  D.  Hager,  Geological  Beport,  1861 ;  1871, 
A.  Wing,  the  fossils  of  the  Chazy  from  West  Rutland,  Vt.,  reported  on  by  E.  Billings  in 
1872 ;  1865  to  1877,  A.  Wing,  fossils  in  central  Vermont,  of  the  age  of  the  Calciferous  to 
the  Trenton,  reported  in  1877  ;  1879,  T.  N.  Dale  of  the  Hudson  age,  from  the  slates  near 
Poughkeepsie,  N.Y.  ;  1879  to  1890,  W.  B.  Dwight,  fossils  from  Dutchess  County,  N.Y.,  of 
Cambrian  to  Trenton  and  Hudson,  and  in  Canaan,  N.Y.,  1886  to  1890;  C.  D.  Walcott, 
fossils  of  Cambrian  age  in  the  quartzyte  of  southern  Vermont,  almost  down  to  the  Mas- 
sachusetts line,  and  in  shales  or  limestone  of  Washington  and  Rensselaer  counties,  N.Y. ; 
also  Trenton  or  Calciferous  fossils  in  the  limestone  of  Bennington,  Vt.,  and  in  Williams- 
town,  Mass.,  on  the  west  flank  of  Greylock,  and  in  Berlin,  N.Y.,  the  region  of  the  original 
Lower  Taconic.  Further,  J.  E.  Wolff  and  Foerste  have  found  Cambrian  fossils  in  the 
limestone  of  Vermont,  near  Rutland,  and  elsewhere. 

It  has  thus  been  established  that  the  Lower  Taconic  is  a  combination  of  Lower 
Silurian  and  Cambrian  formations,  as  already  stated.  The  author's  stratigraphical  inves- 


496  HISTORICAL   GEOLOGY. 

tigations  in  Berkshire,  Mass.,  Vermont,  eastern  New  York,  and  western  Connecticut,  aim- 
ing to  prove  the  continuity  of  the  rocks  of  the  belt  so  as  to  use  the  Vermont  fossils  to  prove 
their  age,  began  in  1871,  and  were  continued  at  intervals  to  1887.  The  last  four  seasons 
were  employed  in  obtaining  data  for  a  geological  map  of  a  large  part  of  the  region. 

For  papers  by  Dale,  D  wight,  Walcott,  and  the  author,  and  an  account  of  Wing's  dis- 
coveries, see  the  American  Journal  for  the  years  mentioned  ;  and  for  a  brief  history  of 
Taconic  ideas,  vol.  xxxvi.,  1888.  The  more  important  of  the  species  of  fossils  discovered 
by  Wing  and  identified  by  Billings,  and  their  varieties,  are  mentioned  beyond,  on  page  517. 

The  Upper  Taconic  of  Emmons,  as  shown  by  the  fossils  at  Reynold's  Inn,  north- 
east of  Bald  Mountain,  Washington  County,  N.Y.,  is  Lower  Cambrian;  and  that  of 
Georgia,  Vt.,  another  locality,  is  the  same. 

Quebec  group  in  Canada.  —  The  Quebec  group  of  Logan  (1861-63),  established  on 
rocks  occurring  near  Quebec,  at  Point  Levis,  and  to  the  south,  included  (1868):  (1)  the 
Levis  beds,  which  were  fossiliferous  ;  (2)  the  Lauzon  beds,  green  and  purple  shales, 
affording  Lingula  and  Obolella ;  and  (3)  the  Sillery  sandstone,  consisting  of  sandstones 
and  shales.  They  were  regarded  by  Logan  and  Billings  as  mostly  of  the  age  of  the  Cal- 
ciferous  and  Chazy  groups.  The  recent  investigations  of  Selwyn  (1877,  1882,  and  later), 
and  the  confirmatory  studies  of  R.  W.  Ells  (1880),  have  proved  that  the  fossiliferous  beds 
include  rocks  from  the  Hudson  epoch  to  the  Cambrian  ;  that  the  Levis  is  Calciferous  in 
its  lower  parts ;  that  the  Sillery  is  probably  all  Cambrian.  (Selwyn,  Rep.  G.  Can.  for 
1880, 1881,  1882  ;  Ells,  ib.  for  1889  ;  also  Walcott,  Am.  Jour.  Sc.,  Feb.,  1890  ;  also  on  the 
Graptolites,  Lapworth,  Trans.  R.  Soc.  Can.,  1886.)  The  Quebec  group  is  for  the  most 
part  a  northern  portion  of  the  Taconic  series. 

In  Newfoundland  the  Quebec  series,  consisting  of  limestones  and  sandstones,  is 
described  by  Logan  and  Murray  as  occurring  on  the  northwest  and  west  coast  of  New- 
foundland, along  the  Straits  of  Belle  Isle,  and  to  the  south.  It  includes  the  Calciferous, 
Cambrian,  and  other  beds  overlying  the  Archaean.  The  thickness  given  for  the  Newfound- 
land-Quebec group  is  4600'.  For  the  original  account  of  the  Quebec  group,  see  Logan's 
Report  on  the  Geology  of  Canada,  1863,  pages  225  and  844. 

LIFE. 

Of  the  terrestrial  animal  life  of  the  Lower  Silurian  era  nothing  is  yet 
known  from  American  rocks ;  but  Insects  are  already  reported  from  those 
of  Europe.  The  aquatic  animals  comprised,  besides  many  new  species  of 
the  several  grand  divisions  represented  in  the  Cambrian,  other  kinds  show- 
ing progress;  and  among  these,  the  earliest  of  Vertebrates  —  FISHES,  as 
recently  announced  by  C.  D.  Walcott ;  the  first  known  of  Barnacles,  a  group 
still  common  along  all  seashores,  and  the  first  of  the  Eurypterids,  a  tribe 
somewhat  resembling  Crustaceans,  but  having  their  only  modern  representa- 
tives in  four  species  of  Limulus. 

1.  CANADIAN  PERIOD. 
1.   Calciferous  Epoch. 

In  the  rocks  of  the  Calciferous  epoch  fossils  are  usually  few,  although 
the  limestones  have  great  thickness.  Since  such  limestones  are  made  mainly 
out  of  calcareous  animal  relics,  the  absence  of  fossils  means  that  the  tritura- 
ting waters  obliterated  them  by  reducing  them  to  the  calcareous  mud  which 
became  the  limestone.  At  some  localities  fossils  are  abundant,  and  there  is 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


497 


no  doubt  that  the  seas  were  everywhere  well  populated.  Among  the  occur- 
ring fossils  in  the  shales,  Graptolites  (Figs.  604-609)  are  often  very  numer* 
ous.  The  American  rocks  have  afforded  a  number  of  Sponges,  a  few  Crinoids 
and  Corals,  some  Bryozoans,  many  Brachiopods,  few  Lamellibranchs,  some 
Pteropods  and  Gastropods,  and  a  number  of  Orthocerata  and  Trilobites. 

PLANTS. — But  little  is  known  of  the  Seaweeds,  as  only  casts  of  rounded 
stems,  sometimes  simple,  often  more  or  less  entangled,  and  consisting  of  the 
material  of  the  rock,  have  been  found  —  and  the  vegetable  nature  of  these 
forms  is  doubted.  The  coal  nodules  (page  493)  are  supposed  to  have  been 
once  in  the  state  of  mineral  oil,  and  may  have  been  derived  from  the  decom- 
position of  organic  matter  of  any  kind.  The  hot  moisture  which  consolidated 
the  rock  and  made  the  siliceous  solution  for  the  associated  quartz  crystals 
(in  which  the  coal  is  sometimes  enveloped)  probably  drove  the  oil  from  the 
beds  and  led  to  its  collection  in  the  cavities  or  geodes. 

ANIMALS.  —  Some  of  the  Sponges  were  of  large  size.  Fig.  596  represents 
a  specimen  (the  lower  part  restored)  of  a  species  of  Archceoscyphia  described 
by  Billings,  which  attained  a  length  of  two  or  three  feet  and  a  diameter  of 
four  inches.  These  Sponges  are  Hexactinellid  in  type;  that  is,  have  six- 
rayed  siliceous  spicules  (the  rays  at  right  angles  with  one  another).  These 


596. 


596-698. 


598. 


SPONGIOZOANS.  —  Figs.  596,  a,  Archseoscyphia  Minganensis  ;   597,   Eeceptaculites  elegantulus,  drawn  from  a 
gutta-percha  cast ;  598,  R.  Calciferus,  fragment  showing  inner  surface.    Billings. 

species  are  from  the  Mingan  Islands.  Other  Hexactinellid  Sponges,  from 
Little  Metis,  Canada,  of  the  genus  Protospongia  of  Salter,  are  represented 
in  Figs.  599  to  603,  natural  size.  Another  species  of  sac-like  form  —  and 
rhombic  meshes  half  an  inch  wide,  Palceosaccus  Dawsoni  of  Hinde  —  had  a 
diameter  of  14  inches.  They  are  from  the  base  of  the  Levis  beds,  Quebec 
group,  and,  according  to  Dawson,  are  not  newer  than  the  Calciferous.  The 
Keceptaculites  (Figs.  597,  598)  are  supposed  to  be  Sponges. 
DANA'S  MANUAL  —  32 


498 


HISTORICAL   GEOLOGY. 


Some  of  the  Graptolites — Hydrozoans  —  are  represented  in  Figs.  604-609. 
The  texture  of  the  fossil  Graptolite  was  usually  thinner  than  the  most  delicate 


599-603. 
600 


602 


SPONGES.  — Fig.  599,  Protospongia  tetranema  (1);  60  \  P.  mononema  ;  601,  P.  cyathiformis ;  602,  P.  coronata; 
603,  P.  Q>uebecensis.     All  from  Dawson. 

membrane.  Only  the  finest  of  sediments  were  therefore  adapted  to  their 
preservation.  The  forms  with  one  row  of  cells,  or  one-edged  (Monoprio- 
nidse),  are  represented  by  the  Loganograptus  (Figs.  604-606)  and  species  of 


604-609. 


605 


GRAPTOLITES.  —  Fig.  604,  Loganograptus  Logani,  branches  broken  off ;  605,  portion  of  a  stem ;  606,  same,  more 
enlarged ;  607,  608,  Phyllograptus  typus  ;  609,  the  supposed  young  of  a  Graptolite.     Hall. 

other  genera.     They  occur  either  in  long,  flat,  notched  threads  spreading  from 
a  center  (Fig.  604),  or  in  simple  forms;  but  most  specimens  are  only  frag- 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


499 


610. 


ments  of  branches  of  the  slender  polypary.     The  diameter  of  the  form  Fig. 

604,  when  living,  and  having  its  arms  of  full  length,  may  have  been  15  to  20 

inches.     Figs.  607,  608  represent  a  species  of  the  two-edged  forms  (Diprio- 

nidae),  that  is,  those  having  cells  along  both  margins. 

Besides  Graptolites,  there  were  massive  Hydrozoan  corals,  of  the  JStroma- 

topora  type,  related,  it  is  supposed,  to  the  modern  Millepora. 
Under    Echinoderms,    there    were 

Crinoids  and   Cystoids,  and  also  the 

earliest    known    of    American     Star- 
fishes (Fig.  610).     Among  the  Brachi- 

opods,  a  common  species  is  the  Orthis 

(BilUngsella)  grandceva  (Fig.  611). 
Gastropods,  of  flat  or  short  spiral 

forms,  like  Figs.  612-614,  of   species 

of  the  genus  Ophileta  and  Madurea, 

were  common,  and  some  were  of  large 

size.     The  genus  Platyceras  continued 

on  from   the   Cambrian.     There  were 

also  spiral  forms  of  the  genera  Pleu- 

rotomaria,  Murchisonia,  Holopea  (Fig.  615),  and  others  of  the 
Bellerophon  family.  The  shells  of  Cephalopoda  in  the  Cal- 
ciferous  beds  occur  of  many  and  varied  forms,  and  some  are 
over  a  foot  in  length.  Those  of  the  genus  Orthoceras  are 
straight  or  slightly  curved.  In  0.  primigenium  of  Vanuxem, 
first  described  from  the  Mohawk  Valley,  N.Y.,  the  septa,  as 
shown  in  Fig.  618,  are  closely  crowded.  A  curved  species  is 

represented  in  Fig.  620,  Cyrtoceras  (?)  Vassarinum  from  Dutches s  County,  N.Y. 

612-616. 


Stenaster  Huxleyi  (x  4).    Billings. 


Orthis     (Billings- 
ella)  grandseva. 


QASTBOPODS.  —  Fig.  612,  612  a,  Ophileta  complanata  (1),  opposite  sides;  613,  O.  levata  (1);  614, 0.  uniangulata 
(1);  615,  Holopea  dilucula.  —  OSTBACOID  CRUSTACEAN:  616,  Leperditia  Anna  enlarged,  side  view;  616  a, 
same,  upper  view ;  616  b,  several  of  the  shells,  natural  size.  Figs.  612,  612  a,  Whitfleld  ;  613,  614,  615,  Hall ; 
616,  616  a,  6,  T.  R.  Jones. 

There  were  also  coiled  species,  both  the  open-coiled  of  the  genus  Lituites, 
and  others  that  were  close-coiled,  Nautilus-like.  Lituites  (?)  imperator  B., 
Philipsburg,  Canada,  had  a  diameter  of  10£  inches. 


500 


HISTORICAL   GEOLOGY. 


617-620. 


Trilobites  existed  of  the  Cambrian  genera  Agnostus,  Dicellocephalus,  Pty- 
choparia,  Bathyurus  (seven  species  or  more),  and  Bathyurellus  (Figs.  621-624), 
and  also  of  the  genera  Illcenus,  Asaplius,  Ceraurus  (Cheirurus),  Amphion, 
Ampyx,  which  have  here  their  first  American  species. 

An  Ostracoid,   or   bivalve   Crusta- 
cean,   is    represented    much    enlarged 

617-  620.  in  Fig.  616  (a  profile  view  in  616  a), 

and  several  of  natural  size  in  the  rock 
in  Fig.  616  b. 

Characteristic  Species. 

1.  Spongiozoans.  —  Beceptaculites   ele- 
gantulus  B.  (Fig.  597)  was  a  hollow  sponge, 
with  the  thickness  to  the  inner  tube  about 
half  an  inch  ;  tubes  passed  from  the  outer 
to  the  inner  surface,  which  opened  inward. 
The  species  from  Little  Metis  (Figs.  599- 
603)   occur  in  beds  that  contain   also   the 
Brachiopod  Linnarssonia  pretiosa  B.  (Daw- 
son,  Trans.  Roy.  Soc.  Canada,  1889).     The 
stem  of  Protospongia  mononema  (Fig.  600) 
is  of  doubtful  reality,  according  to  Hinde. 

2.  Hydrozoans.  —  The  characteristic  Cal- 
ciferous  forms,  besides  those  figured,  are  Phyl- 
lograptus  Anna  H. ,  Tetragraptus  bryo noides 
H.,  T.  fruticosus  H.,  Didymograptus  exten- 
sus  H.,  all  of  the  vicinity  of  Quebec.     The 
Cryptozoon proliferum  H.(1884),  from  Green- 
field, Saratoga  County,  N.Y.,  and  C.  Steeli, 
Seely  and  Br. ,  another  species  from  Vermont, 
if  really  organic,  perhaps  belong  here. 

3.  Echinoderms.  —  Stenaster  Huxley i  B. 
(Fig.  610),  having  a  breadth  of  5  lines,  is  from 
Point  Rich,  Newfoundland. 

4.  Molluscoids.  —  Fig.  611,  Orihte  (Bil- 
lingsella}  grandceva  B. ;  Lingula  acuminata, 
Camarella  calcifera  B. ;  C.  varians  B.  (also 
from  Newfoundland);  Clitambonites. 

5.  Mollusks,  —  a.  Lamellibranchs.     Eu- 
chasma    Blumenbachii    B.,    Newfoundland  ; 
Tellinomya  Angela  B. 

6.  Gastropods.  —  Ophileta  compacta  S.,  a  fine  species  from  Canada,  is  H  inches  across  ; 
Pleurotomaria  Calcifera  B.,  from  near  Beauharnois,  Canada;  P.  gregaria  B.,  St.  Ann's, 
island  of  Montreal,  Canada,  extremely  abundant ;  Maclurea  matutina  H.,  from  New  York 
and  Canada ;  Murchisonia  Anna  B.  (a  long  turreted  shell,  approaching  the  M.  bellicincta, 
Fig.  675),  St.  Ann's,  the  Mingan  Islands;  Eccyliomphalus  priscus  Whitf.,  a  large  open- 
coiled  shell  from  Fort  Cassin,  Vt. 

c.  Cephalopods.  — Orthoceras  Ozarkense  Shum.  is  from  the  Magnesian  limestone,  Ozark 
County,  Mo.;  Lituites  (?)  Farnsworthi  B.,  a  species  partly  coiled,  and  nearly  5  inches  in 
its  longer  diameter,  and  L.  imperator  B. ,  are  from  the  upper  part  of  the  Calcif erous  sand- 


CEPHALOPODS.  —  Figs.  617,  618,  Orthoceras  primige- 
nium;  619,  Kionoceras  (Orth.)  laqueatum  ;  620. 
Cyrtoceras  (?)  Vassarinum.  Figs.  617,  618,  619^ 
Hall ;  620,  W.  B.  Dwight. 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


501 


rock  of  Philipsburg,  Canada  East;  Piloceras  Canadense  B.,  from  the  Mingan  Islands, 
north  of  Anticosti  Island;  P.  Wortheni  B.,  from  western  Newfoundland.  Nautilus 
pomponius  B.  is  from  Philipsburg  ;  N.  ferox  B.,  Mingan  Islands,  is  referred  by  Hyatt  to 
the  genera  Plectoceras  and  Litoceras,  there  being  no  true  species  of  Nautilus  in  Paleozoic 
rocks.  At  Philipsburg,  Fort  Cassin,  and  in  Newfoundland,  the  fauna  included  also,  accord- 
ing to  Hyatt,  species  of  the  genera  Sannionites  (Fischer,  Hyatt),  Endoceras  Hall,  and 
Actinoceras  Bronn  (=  Ormoceras  Hall).  On  Hyatt's  review  of  the  genera  of  Fossil 
Cephalopods,  see  Proc.  Boston  Soc.  Nat.  Hist.,  xxii.,  253,  1883. 


621-624. 


623. 


621. 


622. 


Figs.  621,  622,  Bathyurus  Saffordi; 


624. 


5,  Bathyurellus  nitidus ;  624,  Bathyurus  (?)  crotalifrons.    Figs.  621-623, 
Billings ;  624,  Dwight. 


6.  Crustaceans.  —  Among  Trilobites,  Bathyurus  Saffordi  B.  (Figs.  621,  622)  is  com- 
mon in  Canada,  and  occurs  also  in  Newfoundland  and  Idaho ;  B.  crotalifrons  at  Rochdale, 
N.Y.  ;  B.  armatus,  Quebec  and  Saratoga  County,  N.Y. ;  Ptychaspis  speciosa,  Ptychoparia 
Calcifera,  P.  Hartti,  are  other  Saratoga  County  species.  Bathyurellus  nitidus  B.  (Fig. 
623)  is  from  Cow  Head,  Newfoundland.  None  of  these  species  occur  in  the  Trenton. 

The  Calciferous  fossils  reported  by  S.  Calvin  from  the  Lower  Magnesian  limestone  of 
Iowa  are  Metoptoma  alta  Whitfield,  Straparollus  Claytonensis  Calvin,  S.  pristiniformis 
Calvin,  Raphistoma  Pepinense  Meek,  H.  multivolvatum  Calvin,  Holopea  turgida  Hall, 
Orthoceras  primigenium  V.,  0.  Luthei  Calvin. 

2.    Chazy  Epoch. 

In  the  Chazy  limestone  occur  small  concretion-like  forms  (Fig.  625)  hav- 
ing the  structure  represented  in  Fig.  626,  which  are  supposed  by  some  to 
be  of  vegetable  origin,  and  by  others, 
a  Sponge  or  the  secretions  of  Hydro- 
zoans. 

The  Corals  of  the  period  include 
Cyathophylloids,  a  tribe  that  dates 
from  the  early  Cambrian ;  massive 
columnar  Corals  of  the  genus  Colum- 
naria;  and  species  with  quadrangular 
cells,  of  the  genus  Tetradium  —  this 
name,  from  the  Greek  for  four,  re- 
ferring to  the  form  of  the  cells  (see 
Fig.  707,  page  511,  for  a  Trenton 
species). 

One  of  the  Cystoids  is  represented  in  Fig.  628,  and  the  body  of  a  Crinoid 
in  Fig.  627.  The  stem  is  wanting  in  each. 


Xi';;S:iV;'fe:S;* 


Fig.  626,   Girvanella  ocellata;   626,  interior  enlarged. 
Seely. 


502 


HISTORICAL  GEOLOGY. 


1.  Molluscoids.  — Fig.  630  shows  a  branching  coral-like  species  of  Bryozoan, 
Sulcopora  fenestrata  H.,  and  Fig.  629  one  of  the  reticulate  kinds,  Subretepora 


627-638. 


639. 


CBINOIDS. — Fig.  627,  Palseocrinus  striatus;  628,  Malocystites  Murchisoni.  MOLLUSCOIDS. — 629,  Subretepora 
incepta;  630,  Sulcopora  fenestrata;  631,  Orthis  costalis;  632,  Strophoraena  plicifera;  633,  Ehynchonella 
plena.  MOLLUSCS.  —634,  Maclurea  magna;  635,  M.  Logani  (x  J);  635  a,  operculum  of  same;  636,  Scalites 
angulatus;  637,  Bucania  rotundata.  CRUSTACEANS.  —  638,  Leperditia  Canadensis,  var.  nana.  Figs.  627, 
628,  Billings;  629-634,  and  636,  637,  Hall;  635,  635  a,  Salter;  638,  T.  E.  Jones. 

incepta  H. ;  and  Fig.  a  for  each  is  an  enlarged  view  of  the  surface.  Some  of 
the  common  Brachiopods  are  Orthis  costalis  H.  (Fig.  631),  Strophomena  (?) 
plicifera,  H.  (Fig.  632),  and  Rhynchonella  plena  H. 

2.  Mollusks.— Figs.  634  to  637  show  the  forms  of 
various  Gastropods;  634  is  the  very  abundant  Mac- 
lurea magna;  it   is  often  eight  inches  in   diameter. 
Fig.  635  is  a  view  of  another  species  which  shows 
also  the  operculum  closing  the  aperture ;  and  635  a 
is  the  separated  operculum.     Fig.  637,  Bucania  rotun- 
data, is  related  to  Bellerophon. 

3.  Crustaceans.  —  Ostracoid  Crustaceans  of  the  spe- 
cies Leperditia  Canadensis  (Fig.  638)  are  common. 

Several  Cambrian  genera  of  Trilobites,  Dicellocephalus  and  others,  had 
disappeared,  Bathyurus  had  lost  the  prominence  it  had  in  the  Calciferous 
era,  and  the  genera  Illcenus,  Asaphus,  Ceraurus,  Amphion,  were  continued 
on  with  new  species.  Fig.  639  represents  the  pygidium  of  an  Amphion. 


Arnphion  Canadensis. 
Billings. 


1.  Rhizopods.  —  Girvanella  of  Nicholson  and  Etheridge  (1878),  made  by  them  doubt- 
ingly  Foraminiferous,  includes,  according  to  its  describers,  Strephochetus  (Figs.  625,  626) 


PALEOZOIC   TIME  —  LOWER   SILURIAN.  503 

of  Seely  (1885),  who  referred  it  to  the  Sponges,  and  Siphonema  of  Bornemann  (1886), 
who  placed  it  among  the  Algae.     It  is  made  a  calcareous  Alga  by  Rothpletz  (1891). 

2.  Spongiozoans.  —  Eospongia  (Astylospongia)  Bcemeri  B.  and  E.  varians  B.  occur 
at  the  Mingan  Islands. 

3.  Actinozoans.  —  Columnaria  incerta  B.  and   C.  parva  B. ;   the   Cyathophylloid, 
Streptelasma  expansum  H. ;  Monticulipora  patula  B.,  M.  adhcerens  B.,  from  Canada. 

4.  Echinoderms.  —  (1)  Crinoids.  — Palceocrinus  striatus  (Fig.  627),  the  body,  show- 
ing the  five   radiating    ambulacral    grooves    at  top ;    Blastoidocrinus  carcharidens  B. 
(2)  Cystoids.  —  Malocystites  Murchisoni  B.  (Fig.  628)  has  the  body  nearly  spherical 
(whence  the  name,  from  the  Latin  malum,  an  apple),  the  ambulacral  grooves  irregularly 
radiating;  M.  Barrandi  B.,  Palceocystites  tenuiradiatus  B.,  which  is  common,  and  has 
been  identified  but  doubtfully,  from  crinoid  stems  from  crystalline  limestone  of  West  Rut- 
land (Am;  Jour.  Sc.,  III.  iv.  133)  ;  also  P.  Dawsoni  B.,  P.  pulcher  B.,  P.  Chapmani  B., 
from  Canada. 

5.  Molluscoids.  —  Other  species  are  Bafinesquina  incrassata  H.,  which  continues  into 
the  Trenton  Strophomena  (?)  plicifera  H.,  Rhynchonella  acutirostris  H.,  B.  altilis  H., 
Bafinesquina  fasciata  H.,  in  the  Upper  Chazy  ;  Lingula  Lyelli  B.,  L.  Huronensis  B.,  etc. ; 
Orthis  imperator  B.,  a  species  nearly  1£  inches  across. 

NOTE.  — Hall  proposes  (1892)  the  generic  name  Bafinesquina  for  the  species  of  Stro- 
phomena of  the  type  of  S.  alternata,  restricting  the  name  Strophomena  to  resupinate  species 
like  S.  planumbona.  He  applies  the  name  Leptcena  to  forms  like  S.  rhomboidalis,  and 
restores  Pander's  generic  name  Plectambonites  to  species  commonly  known  as  Leptcena, 
as  L.  sericea  and  L.  transversalis  (Hall,  Pal.  N.  Y.,  vol.  viii.,  Genera  of  Paleozoic  Brachi- 
opoda,  1892). 

6.  Mollusks.  —  (a)  Lamellibranchs. —  Cypricardites  (Vanuxemia)  Montrealensis  B. 
—  a  species  nearly  1£  inches  long. 

(&)  Gastropods. — Besides  the  species  figured,  other  common  kinds  are  Baphistoma 
planistrium  H.,  Pleurotomaria  biangulata  H.,  P.  antiquata  H.,  Bucania  sulcata  (Bucania 
differs  from  Bellerophon  only  in  having  the  outlines  of  the  spire  show  externally  on 
either  side).  Metoptoma  dubia  H.,  Platyceras  auriformis  H. 

(c)  Cephalopods. —  Orthoceras  rectiannulatum  H.,  also  found  in  the  Birdseye  lime- 
stone ;  O.  tenuiseptum  H.,  septa  very  thin  and  rather  crowded ;  O.  velox  B.,  Montreal, 
Mingan  Islands;  O.  diffidens  B.,  Mingan  Islands;  0.  Allumettense  B.  (which  is  also  a 
Black  River  limestone  species). 

7.  Crustaceans.  —  The  Trilobites,  Illcenus  Arcturus  H.;  Asaphus  obtusus  H.,  A.  (Iso- 
telus)  canalis  Conr.,  New  York  and  Canada,  A.  marginalis  H.,  and  also  Quebec  group 
of  Newfoundland.     Bathyurus  Angelini  B.;  Ceraurus  Satyrus  B.,  at  Montreal.     The 
earlier  genera,  Dicellocephalus,  Crepicephalus,  Menocephalus,  Bathyurellus,  Loganellus, 
Nileus,  are  not  represented,  so  far  as  known,  in  the  Chazy  or  later  periods. 

The  Ostracoids,  Leperditia  Canadensis  Jones,  Fig.  638,  from  Grenville,  Huntley,  and 
elsewhere  in  Canada  ;  L.  amygdalina  Jones,  from  near  L'Original,  Canada. 

In  the  gorge  of  the  Kentucky  River,  near  the  mouth  of  Cooper's  branch,  Ulrich  reports 
a  limestone  stratum  (150'  thick)  as  affording  the  Chazy  species  Maclurea  magna,  Baph- 
istoma planistrium,  Bhynchonella  dubia  H.,  Sulcopora  fenestrata,  Leperditia  Canadensis, 
with  Orthis  subcequata  Conr.  a  Trenton  species,  Orthoceras  explorator  B.  a  Quebec  species 
and  0.  furtivum  B.  a  Calciferous  species ;  with  also  species  of  Bathyurus,  Dalmanites, 
Pterotheca,  and  the  Trenton  Bryozoan  Mitoclema  cinctosum  Ulr. 

Other  species  described  by  Billings,  in  Can.  G.  Bep.  of  1863,  are  Monticulipora  (Sten- 
opora)  fibrosa  ;  Bhynchonella  orientalis,  Camarella  varians,  C.  longirostris,  Orthis  platys, 
0.  borealis,  O.  Porcia,  O.  acuminata,  0.  disparilis  Con.  (from  the  Chazy  and  Trenton)  ; 
Pleurotomaria  calyx,  P.  docens ;  Illcenus  globosus,  I.  Bayfieldi,  Sphcerexochus  parvus 
(from  the  Chazy  and  Black  River),  Harpes  antiquatus. 


504 


HISTORICAL   GEOLOGY. 


2.   TRENTON  PERIOD. 
1.  Trenton  Epoch. 

PLANTS. — Two  of  the  forms  referred  to  Algae  or  Seaweeds  are  here  repre- 
sented. They  are  much  like  the  so-called  Fucoids  of  earlier  and  later  time; 
but  whether  of  vegetable  origin  is  questioned. 


640. 


641. 


ALG.E.  —  Fig.  640,  Buthotrephis  gracilis  ;  &41,  B.  succulens.     Hall. 

Specimens  of  supposed  terrestrial  plants  have  been  reported  from  the 
Cincinnati  beds  of  Ohio  and  Kentucky ;  but  no  certain  evidence  from  fossils 
of  vegetation  over  the  land  had  been  found  up  to  the  year  1894. 


642. 


643. 


SPONGE.  —  Brachiospongia  digitata.    Beecher. 

ANIMALS.  1.  Spongiozoans.  —  A  large  branching  Hexactinellid  Sponge, 
Brachiospongia  digitata,  from  the  Trenton  of  Kentucky  and  Tennessee,  is 
represented  in  different  positions  in  Figs.  642,  643.  The  number  of  short 
branchings  varies  from  8  to  12,  and  specimens  having  12  are  sometimes 
10J  inches  in  diameter. 

2.  Hydrozoans  are  represented  by  Graptolites  (647,  a)  and  Stromatoporids. 

3.  Actinozoans  comprise  Cyathophylloid  Corals  like  Fig.  644,  Streptelasma 
comiculum  H. ;  and  tabulate  Corals  as  Columnaria  alveolata  H.,  —  the  term 
tabulate  referring  to  the  horizontal  partitions  seen  in  vertical  sections  of  the 
columnar  cells  (Fig.  645). 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


505 


There  were  also  many  of  the  minutely  columnar  Corals,  of  the  Monticuli- 
pora  family,  differing  from  Ohcetetes,  to  which  genus  they  were  formerly 
referred  in  having  the  columns  separable.  Prasopora  lycoperdon,  Fig.  646, 
is  a  hemispherical  species,  having  the  structure  shown  in  Fig.  646  a ;  others 
are  branching  and  foliaceous  forms.  The  branching  Corals  which  form 
the  crystalline  points  called  "birdseyes"  in  the  Birdseye  limestone  are 


644-651. 


RADIATES.  —  Fig.  644,  Streptelasma  corniculum;  645,  Columnaria  alveolata;  645 a,  surface  showing  cells;  646, 
Prasopora  lycoperdon ;  646  a,  transverse  section  of  same ;  647,  portion  of  Diplograptus  amplexicaulis  ;  647  a, 
same  enlarged ;  648,  Palaeaster  matutinus ;  649,  Taeniaster  spinosus ;  650,  Taxocrinus  elegans ;  651,  Pleuro- 
cystites  filitextus.  Figs.  644,  645,  Hall ;  646,  647,  Meek ;  648-651,  Billings. 

referred  to  the  genus  Tetradium,  distinguished  by  its  four-sided  cell  with  four 
points  within  it,  as  in  Fig.  707,  page  511.  These  peculiar  fossils  were  first 
called  Fucoids  by  Conrad,  and  later  named  Phytopsis  cellulosa  by  Hall,  the 
generic  name  referring  to  the  resemblance  to  plants. 

4.  Echinoderms  include  true  Crinoids  (Fig.  650),  Cystoids  (Fig.  651), 
Asterioids,  under  which  are  true  Starfishes  (Fig.  648),  and  the  Ophiuroids 
or  Serpent-star  (Fig.  649). 

5.  Molluscoids.  —  Three  species  of  the  Trenton  Bryozoans  are  represented 
on  the  next  page  from  a  memoir  by  Ulrich  (1893);  Fig.  652,  of  a  Stictoporella, 
represents  the  retiform  frond  of  natural  size,  and  653,  a  portion  between  two 
of  the  spaces  much  enlarged,  showing  the  cells.     Fig.  654  is  a  jointed  branch- 
ing form  from  Ottawa,  Canada,  natural  size,  and  655  represents  three  joints 
much  enlarged. 

On  page  507  are  figures  of  common  Trenton  Brachiopods  of  the  genera 
and  species  named  underneath.      The  figures   are    mostly  from  specimens 


506 


HISTORICAL   GEOLOGY. 


obtained  in  the  beds  of  Cincinnati  of  the  Hudson  period,  and  in  part  differ 
somewhat  in  habit  from  those  of  the  Trenton  limestone. 


652-655. 


652. 


653. 


BKYOZOANS.  —  Fig.  652,  Stictoporella  cribrosa  (1)  ;  653,  same 
(x  18) ;  654,  Arthroclema  Billingsi  (1) ;  655,  A.  cornutum 
(x  7).  Ulricli. 

6.  Mollusks.  —  Some  of  the  Lamelli- 
branchs  are  figured  in  Nos.  670-672,  and 
also  709-712  (page  511) ;  and  Gastropods  in 
Figs.  673-681.  Fig.  673  represents  a  Ra- 
phistoma-y  674,  675,  species  of  the  genus 
Murchisonia ;  677,  678,  a  Belleroplion  in 
different  views ;  and  679-681,  species  of 
the  related  genus  Cyrtolites,  symmetrical 
shells  of  swimming  Mollusks,  related  to 
the  modern  Atlantis  (Heteropods). 

Pteropods  were  represented  by  species 
of  Pterotheca,  and   of  Conularia;   in   the 
latter,  the  shell  admits  of  some  movement  along  vertical  sutures  (Fig.  682). 

A  few  of  the  shells  of  Cephalopods  are  represented  on  page  508 :  Fig. 
683,  Orthoceras  junceum  H. ;  the  cross-lines  representing  the  partitions  or 
septa,  and  Fig.  a,  a  transverse  section,  showing  the  position  and  size  of 
the  siphuncle.  Fig.  685,  part  of  the  shell  of  Actinoceras  Bigsbyi  of  Bronn 
(1837);  the  whole  length  of  the  shell  when  entire  was  over  a  foot;  the 
view  is  of  a  section  showing  the  large  beaded  siphuncle  within ;  686,  Cyrto- 
ceras  subannulatum  D'Orb. ;  and  687,  688,  species  of  Trocholites,  T.  undatus 
and  T.  Ammonius  of  Conrad.  In  another  genus,  Endoceras,  from  the  Black 
River  limestone,  some  specimens  have  a  diameter  exceeding  a  foot,  and  a 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


507 


length  of  10  or  12  feet.  They  were  the  largest  and  most  powerful  animals 
of  the  seas ;  but  they  must  have  been  much  encumbered  in  locomotion  by 
the  long  bulky  shell. 

656-669. 


BEACHIOPODS.  —  Figs.  656,  657,  Orthis  (Platystrophia)  biforata ;  658,  O.  occidental  ;  659,  O.  testudinaria ;  660, 
O.  tricenaria ;  661,  Leptaena  (Plectambonites)  sericea  ;  662,  Leptsena  rhomboidalis ;  663,  Strophomena  (Eafi- 
nesquina)  alternate ;  664-666,  Rhynchonella  capax  ;  66T,  66T  a,  Cyclospira  bisulcata  ;  668,  Schizocrania  filosa ; 
669,  Lingula  quadrata.  Figs.  656-666  from  Meek ;  66T-669,  from  Hall. 


670-682. 


671 


LAMELLIBEANOHS.  —  Pig.  670,  Pterinea  Trentonensis;   671,  Ambonychia  bellistriata;  672,  Tellinoinya  nasuta. 

_  GASTROPODS.—  Fig.  673,  Eapbistoma  lenticulare;  674,  Murchisonia  Milleri ;  675,  M.  bellicincta  ;  676,  Helicot- 

"  oma  planulata;  677,  678,  Bellerophonbilobftus;  679,  Cyrtolites  compressus ;  680,  681,  C.  (?)  Trentonensis ; 

682,  a,  b,  Conularia  Trentonensis.     Figs.  670,  671, 677-682,  Hall ;  672,  Billings ;  673,  675,  Meek ;  674,  676,  Salter. 


508 


HISTORICAL   GEOLOGY. 


The  genus  Orthoceras  had  many  later  species.  But  Endoceras,  of  which 
there  are  over  twenty  described  American  species,  began  in  the  Canadian 
and  ended  in  the  Trenton  period. 

683-688. 


CEPHALOPODS.  —  Fig.  683,  a,  Orthoceras  junceum ;  684,  0.  olorus  (x%)  ;  685,  Actinoceras  Bigsbyi;  686,  a,  Cyr- 
toceras  subannulatum  D'Orb.  ;  68T,  Trocholites  undatus ;  688,  T.  Ammonius.      Figs.  683-687,  Hall ;  688,  D. 

7.  Crustaceans.  —  Trilobites  were  of  varied  forms  and  many  new  genera ; 
Asaphus,  a  Calciferous  genus,  holds  on ;  and  so  also  Illcenus,  Ceraurus,  and 
Bathyurus;  the  latter  two  have  their  last  species  in  the  Trenton.  Fig.  689 
represents  Asaphus  platycephalus,  from  Trenton  Falls,  N.Y.,  which  is  often 

689-693.     690 


CBUSTAOKANS.  —  Fig.  689,  Asaphus  (Isotelus)  platycephalus  (x  %)  ;  690,  a,  Calymene  callicephala ;  691,  Lichas 
Trentonensis  ;  692,  Trinucleus  concentricus ;  698,  a,  6,  Leperditia  fabulites  (natural  size).  689,  691,  Hall; 
690,  692,  Meek ;  698,  T.  K.  Jone* 


PALEOZOIC   TIME  —  LOWER    SILUKIAN. 


509 


eight  inches  long ;  Calymene  (Figs.  690,  a)  is  still  more  common,  —  690  a 
showing  it  rolled  up,  as  is  often  the  case  (like  a  modern  Oniscus  among 
Crustaceans);  691,  zLichas;  692,  Trinucleus  concentricus  (the  name  referring 
to  the  three  prominences  on  the 
head,  and  its  fillet-like  border) ; 
all  are  found  at  Trenton  Falls. 
Another  common  Trenton  species 
is  the  Ceraurus  pleurexanthemus 
Green.  Fig.  694  represents  an 
under  view  of  the  shell  —  the  ex- 
uvia  of  the  Trilobite.  Walcott 
states  that  out  of  1160  specimens 
found  by  him,  only  50  lay  with 
the  back  upward,  —  a  natural  con- 
sequence of  their  being  mere  empty 
exuviae,  as  they  would  be  likely  to 
float  like  a  boat,  with  the  concavity 
upward. 

Crustaceans  of  the  Ostracoid 
tribe  are  not  rare.  A  Leper ditia 
is  represented  in  Fig.  693. 

8.  Fishes. — Remains  of  Fishes, 

the  earliest  known  Vertebrates,  OCCUr      TKiLOBrra.-Fig.  694,  Ceraurus  pleurexanthemus,  under 
in    rocks    Of    the    Trenton    period.  surface,  natural  size:  2,  the  hypostome;  4,5,  occipital 

__..         , .  ,    ,  depression  and  cavity ;  a,  b,  c,  d,  depressions  in  the 

The  discovery  was  announced  by  8hell  of  the  thorax .  e>  free  pleune    mlcottj  ,75 

Walcott  in  1891.     The  fossils  are 

abundant   in   sandstone   near   Canon   City,   Col.      Most   of    them   are   the 
plates  and  scales  of  Ganoids,  the  largest  about  half  an  inch  across.     Of 


695-697. 


695. 


695  a. 


097  a 


697. 


BEMAIXS  OF  FISHES.  —  Fig.  695,  Astraspis  desiderata,  dermal  plate;  695  a,  id.  (x  3);  696,  Eriptychius  Ameri- 
can us  (x  4) ;  697,  69T  a,  Dictyorhabdus  priscus,  supposed  notochord.    Walcott. 


510 


HISTORICAL  GEOLOGY. 


these  plates,  two,  represented  enlarged  in  Figs.  695,  695  a,  are  referred  to 
Placoderms  (see  page  417),  the  group  which  comprises  the  oldest  Fishes 
previously  known,  those  of  the  Upper  Silurian  and  early  Devonian.  The 
scales,  Fig.  696,  have  the  markings  of  a  typical  Ganoid,  much  like  those  of 
the  genus  Holoptychius,  a  form  not  found  hitherto  in  beds  earlier  than  the 
Middle  Devonian.  Besides  these,  there  are  remains  (Figs.  697,  697  a)  of 
what  are  supposed  to  be  the  ossified  sheaths  of  the  notochord  of  a  species 
of  the  Shark  tribe  related  to  the  Chimaera  (page  416).  The  beds  affording 
these  remains  of  Fishes  contain  many  other  fossils  that  are  referred  to 
the  Lower  Trenton,  and  are  overlaid  by  others  carrying  Upper  Trenton 
fossils. 

2.  Utica  and  Hudson  Epochs. 

Graptolites  abound  in  the  shales  of  the  Utica  and  Hudson  groups, 
especially  the  former.  Thirty  species  or  more  have  been  described  from 
the  Utica  slate,  and  some  of  these  are  represented  in  Figs.  698-702. 


698-703. 


GRAPTOLITES.  —  Fig.  698,  Lasiograptus  (Diplograptus)  mucronatus;  699,  Ccenograptus  gracilis ;  700,  Clima- 
cograptus  bicornis ;  701,  701  a,  Diplograptus  pristis  ;  702,  Dicranograptus  ramosus.  ASTERIOI  i>.  —  Fig.  703, 
Palaeaster  Jamesi.  Figs.  698-702  from  Hall ;  703,  J.  G.  Anthony. 

Corals  occur  of  several  genera.  Favistella,  Fig.  704,  is  a  massive  Coral, 
with  crowded  stellate  cells.  Halysites,  Fig.  705,  grew  in  vertical  plates,  in- 
tersecting one  another ;  in  a  transverse  section  the  cells  look  like  the  loops 
of  a  chain,  whence  the  common  name  chain  coral.  Another  Coral  grew  in 


PALEOZOIC   TIME  —  LOWER   SILURIAN. 


511 


clustered  stems,  Fig.  706,  with  the  cells  above  stellate.     A  species  of  Tetra- 
dium,  T.  fibratum  of  Tennessee,  is  represented  in  Fig.  707. 

Minutely  columnar  Bryozoan  corals  of  the  Monticulipora  tribe  were 
very  numerous,  70  or  75  species  having  been  described  from  the  Cincinnati 
beds. 


704-708. 


70S 


Fig.  704,  Favistella  stellate ;  705,  Halysites  gracilis  ;  706,   Sarcinula  (?)  obsolete ;    707,  a,  Tetradium  fibratum  ; 

708,  Glyptocrinus  decadactylus.     Hall. 

The  Echinoderms  included  Crinoids  and  Cystoids  of  several  kinds.  Fig. 
708  represents  a  fine  Glyptocrinus,  one  of  the  most  common ;  and  Fig.  703,  a 
remarkable  Star-fish  from  the  Cincinnati  beds,  Palceaster  Jamesi  D.  Two 
other  fine  Star-fishes  from  the  same  locality  (P.  Dyeri  Meek  and  P.  magnificus 


709-712. 


LAMELLIBRANCHS.  — Fig.  709,  Avicula  demissa ;  710,  Ambonychia  radiate;  711,  Modiolopsis  modiolaris  (x  f) ; 

712,  Orthodesma  parallelum.     Hall. 


Bryozoan  corals  also  are  com- 


713. 


Miller)  have  a  diameter  of  about  six  inches, 
mon  in  the  Cincinnati  beds. 

The  Brachiopods  are  nearly  the  same  as  in  the  Trenton. 

Lamellibranchs  are  rather  common,  they  being  usually 
more  abundant  in  shales  and  shaly  sandstones  than  in  lime- 
stones. Some  of  the  kinds  are  shown  in  Figs.  709-712. 

Of  the  Gastropods  represented  on  page  507,  Figs.  673-675 
are  also  Hudson  group  species ;  and  the  same  is  true  of  the 
Lituites  ^Trocholites}  Ammonius,  Fig.  688.  Of  Cephalopods,  the  Cincinna>i 
beds  'have  afforded  13  species  of  Orthoceras,  5  o|  Endoceras,  4  of  Lituites, 
and  10  of  other  genera. 


Head-shield    of  Triar- 
thrus  Beckii. 


512 


HISTORICAL   GEOLOGY. 


The  Trilobites  include  Asaphus  platycephalus,  Fig.  689;  a  still  larger 
species,  A.  megistos  Locke,  over  a  foot  long,  the  Calymene  of  Fig.  690,  Lichas 
of  Fig.  691,  and  Trinudeus  of  Fig.  692. 

The  most  common  species  is  the  Triarthrus  Beckii,  and  the  remains 
usually  found  are  simply  the  head-shield,  represented  in  Fig.  713.  The 


714. 


i 


715. 


716. 


TBILOBITES.  —  Fig.  714,  Triarthrus  Beckii,  nat.  size;  715,  a  to  t  (x  3),  young  of  same,  at  different  stages  of 
growth ;  a  ,  the  youngest  stage  (x  15).    Fig.  714,  Beecher ;  715,  a  to  i,  Walcott. 

nearly  entire  Trilobite,  having  its  tentacles  and  many  of  its  legs  protruded, 
found  as  yet  at  but  one  locality  on  the  continent,  —  near  Rome,  N.Y., — 
is  shown  in  Fig.  714,  from  a  sketch  by  C.  E.  Beecher.  Less  perfect  speci- 
mens, from  the  same  place,  as  figured  by 
Matthew,  are  represented  on  page  422. 
The  legs  of  the  left  and  right  sides  of 
Fig.  714  are  from  two  different  specimens, 
bub  are  not  in  any  respect  "  restored." 
Each  has,  as  made  known  by  Beecher,  two 
branches,  and  one  of  them  is 
fringed,  and  thereby  natatory 
in  function.  The  natatory 
branch  is  strictly  an  append- 
age to  the  basal  joint  of 
the  other  branch,  which  is  the 
true  leg.  In  Fig.  716  A  the 
fringe  is  removed  to  show 
the  articulations  ;  in  716  B 
the  limb  is  in  its  entire  state. 
Beecher's  observations  make 
certain  the  close  relations  of  Trilobites  to  Isopod  Crustaceans,  as  stated  on 
pages  421,  422. 


717. 


Fig.  716.  A,  B,  leg  of  Triarthrus  Beckii  (x  12) ; 
A,  leg  with  the  setae  removed  to  show  the 
articulations,  en,  the  main  stem  of  the 
leg  (endopodite);  ex,  the  natatory  branch 
(exopodite).  Beecher. 


Embryonic  form 
of  Triarthrus 
Beckii  (x  80). 
Beecher. 


PALEOZOIC   TIME LOWER    SILURIAN. 


513 


718. 


CIRRIPEDB.  —  Fig.  718, 
Turrilepas  Cana- 
densis,  a  single 
plate  (X  5). 


Under  Fig.  715  are  figures  of  the  young  Trilobite  at  different  stages  of 
growth,  as  made  out  by  Walcott  —  all  magnified  three  times  excepting  a1, 
which  is  the  stage  a  magnified  15  times.  In  this  young  stage  the  thorax 
has  but  one  thoracic  segment,  and  this  has  a  short  spine  on  the  back ;  the 
following  five  segments  are  abdominal.  The  other  figures  (b  to  i)  have  an 
increasing  number  of  thoracic  segments.  Walcott  figures  12  of  these  stages 
of  growth  below  the  adult,  and  nine  are  here  reproduced.  Beecher  has 
observed  a  still  younger  stage  having  no  thoracic  segment,  represented,  mag- 
nified 30  times,  in  Fig.  717. 

Other  genera  of  Trilobites  of  this  epoch  are  Ceraurus,  Acidaspis,  Proetus, 
Dalmanites,  and  Cyphaspis. 

Besides  Ostracoids  of   several  genera,  there  were  also 
the  first  known  species  of  the  Barnacle  or  Cirriped  tribe 
—  the   Turrilepas  Canadensis  Woodward.      The  specimen 
figured  (Fig.  718),  rep- 
resenting   one    of    the 
pieces  of  the  shell,  was 
from  near  Ottawa,  Can- 
ada. 

The  Utica  slate  has 
afforded  the  first  speci- 
mens of  the  Eurypte- 
rids — species  remotely 
related  to  Crustaceans,  and  peculiar  in 
having  five  pairs  of  large  legs  projecting 
either  side  of  the  head  whose  basal  joints 
serve  as  jaws  (page  556).  Fig.  719  rep- 
resents a  leg  of  one  of  the  pairs ;  and  as 

it  is  half  the  natural  size,  the  whole  animal  was  probably  more  than  a  foot 
long.  Its  fringe  of  spines  aided  it  in  swimming,  and  perhaps  also  in  securing 
its  food.  Entire  specimens  of  other  species  of  the  tribe  are  shown  on  pages 
556,  564. 

Characteristic  Species. 

1.  Trenton  Epoch. 

1.  Spongiozoans.  —  Eeceptaculites  Oweni  H.,  characteristic  of  the  Galena  limestone, 
with  H.  globularis  H.,  It.  lowensis  Owen.     Astylospongia  parvula  Bill.,  near  Ottawa  City, 
Canada  ;  Brachiospongia  digitata  (Fig.  642)  is  from  a  paper  by  C.  E.  Beecher,  which  is 
illustrated  by  6  plates,  published  by  the  Peabody  Museum  of  Yale  College.     The  species 
was  first  described  and  figured  by  Troost  in  1839  ;  named  Scyphia  digitata  by  D.  D.  Owen 
in  1858,  and  Brachiospongia  Koemerana  by  Marsh  in  1867.    Beecher  also  describes  in 
the  same  paper  two  other  species  of  Sponge  under  the  generic  name  Strobilospongia ; 
they  occur  with  the  preceding.    The  most  recent  observations  of  Rauff  make  the  supposed 
relations  of  the  Receptaculites  to  the  Sponges  very  doubtful. 

2.  Actinozoans.  —  Fig.  644,  Streptelasma  corniculum  H.,  8.  profundum  Con.,  Trenton 
limestone;  S.  apertum  B.,  Black  River  limestone.     Fig.  645,  Columnaria  alveolata  Goldf., 
Black  River  limestone,  and  Trenton  ;  C.  Halli  Nicholson,  Kentucky  ;  C.  calicina  Nicholson, 

DANA'S  MANUAL  —  33 


Fig.    719,  Leg  of  Echinognathus  Cleveland!. 
Walcott. 


514  HISTORICAL  GEOLOGY. 

from  Kentucky ;  Figs.  646,  646  a,  Prasopora  lycoperdon  ;  Halysites  catenulatus  or  related, 
Galena  limestone,  and  in  Canada;   Tetradium  columnare  H.,  Tennessee. 

3.  Hydrozoans.  — Fig.  647,  Diplograptus  amplexicaulis  H.,  New  York  and  Tennessee  ; 
647  a,  enlarged  ;   Climacograptus ;  Stromatocerium  pustulosum  Saff.,  Tennessee.     Soleno- 
pora  compacta  B.,  Canada,  eastern  New  York,    Kentucky,  looks  like  a  pebble,  and  a 
limestone  made  largely  of  them  resembles  a  conglomerate.     It   occurs   abundantly  at 
Pleasant  Valley,  in  Dutchess  County,  N.Y.  (D wight). 

4.  Echinoderms.  —  Fig.  648,  Palceaster  matutinus  H.,  of  the  Trenton  ;  649,  Tceniaster 
spinosus  B. ;  the  Crinoids,  Taxocrinus  elegans  B.  (Fig.  650),  Agelacrinus  Billingsi  Chap- 
man,   Grlyptocrinus  decadactylus  H.,  Kentucky,  Schizocrinus  nodosus  H.,  Heterocrinus 
Canadensis  B. ;  also  species  of  genera  ffybocrinus,  Porocrinus,  Palceocrinus  ;  and  the  Cys- 
toids,  Comarocystites  Shumardi  M.  &  W.,  Missouri,  C.  punctatus  B.,  Canada ;  Dendrocrinus. 
retractilis  Wale.,  Trenton  Falls,  Calceocrinus  Barrandei  Wale.,  ibid.  ;  Merocrinus  typus 
Wale.,  ibid.,  locrinus  crassus  H.,  ibid. ;  Fig.  651,  Pleurocystites  filitextus  B.,  Amygdalo- 
cystites,  Kentucky. 

5.  Molluscoids.  —  (or)  Bryozoans. — Species  of  Stictopora  and  Ptilodictya  (related  to 
Figs.  629,  630)  are  common  ;  Clathropora  flabellata  H. ;  Stomatopora  arachnoidea  H. 

(&)  Brachiopods.  —  Figs.  656,  657,  Orthis  biforata  Schl.  ;  658,  O.  occidentalis  H.  ; 
659,  O.  testudinaria  Dalm. ;  660,  0.  tricenaria  Con.,  O.  disparilis  H.,  0.  subquadrata  H.t 
and  others  ;  661,  Leptcena  (Plectambonitcs}  sericea  Sow. ;  662,  Leptcena  rhomboidalisWilc. ; 
663,  Strophomena  (Rafinesquina)  alternata  Con.,  S.  incrassata  H.  ;  664-666,  Rhynchonella 
capax  Con. ;  667,  667  a,  Cyclospira  bisulcata  Emm.  ;  Zygospira  modesta  Say ;  668, 
Schizocrania  filosa  H. ;  Crania  scabiosa  H.,  Galena  limestone ;  669,  Lingula  quadrata 
Eichw. ,  and  other  species  ;  also  species  of  Orbiculoidea,  Trematis,  etc. 

6.  Mollusks.  —  (a)    Lamellibranchs.  —  Tellinomya  alta   H.,  Wisconsin,  etc. ;   Am- 
bonychia  attenuata  H.,  Wisconsin,  and  others  ;  Conocardium  immaturum  B.,  Black  River 
limestone,  Ottawa  ;  Modiolopsis  faba  H.,  M.  superba  Bill.,  Wisconsin,  etc.;  Cypricardites 
Niota  H.,  Wisconsin,  C.  rectirostris. 

(&)  Gastropods. — Fig.  673,  Raphistoma  lenticulare  Emm.,  very  common;  Pleuro- 
tomaria  subconica  H.,  and  other  species;  674,  Murchisonia  Milleri;  675,  M.  bellicincta 
H.,  often  4  inches  long,  M.  gracilis  H.,  M.  tricar inata  H.  ;  676,  Helicotoma  planulata 
Salter,  Canada,  Cyclonema  bilix  Con.,  Ophileta  Owenana  M.  &  W.,  Galena  limestone; 
67 7,  Bellerophon  bilobatus  Sow.,  common;  678,  same,  side  view;  679,  Cyrtolites  com- 
pressus  Con. ;  680,  681,  Cyrtolites  (?)  Trentonensis  Con. ;  species  of  Metoptoma,  a  genus 
which  began  in  the  Cambrian,  Holopea,  Trochonema,  Eunema,  Subulites,  etc.  Maclurea 
magna  (Fig.  634) ,  Trenton  of  middle  Tennessee  (Safford)  ;  Chiton  Canadensis  B.  is  a 
Metoptoma,  Black  River  limestone,  Canada. 

(c)  Pteropods.  —  Pteropods  were  represented  by  the  earliest  known  of  the  straight, 
slender  shells  called   Tentaculites ;   T.  incurvus  of  Shumard   is  from  Trenton  beds  in 
Missouri  and  T.  Sterlingensis  and  Oswegoensis  of  M.  &  Worthen  and  T.  Eichmondensis 
of  Miller,  from  the  Cincinnati  group.     There  were  also  Conularise,  and  species  of  the 
Theca  family.     Fig.  682,   Conularia  Trentonensis  H. ;   Pterotheca  attenuata  H. ;   Theca 
parviuscula  H.,   Wisconsin ;    Hyolithes,   frequently  having  septa  within  in  the  smaller 
extremity. 

(d)  Cephalopods. — Fig.  683,  Orthoceras  junceum  H.  ;  0.  anelhtm  Conr.,  (Cycloceras 
anellum  of  Hyatt) ;  684,  O.  olorus  H.  ;  685,  Actinoceras  Bigsbyi  of  Bronn  is  Ormoceras 
tenuifllum  of  Hall,  from  the  Black  River  limestone  ;  good  specimens  show  a  transverse  row 
of  foramina  in  each  of  the  subdivisions  of  the  beaded  siphuncle,  common  in  the  Black 
River  limestone  ;  Endoceras  proteiforme  H.,   Gonioceras  anceps  H.     Endoceras  (K^>CIJ, 
horn,  and  evdov,  within)  has  a  concentric  structure  of  cone  within  cone  in  the  siphuncle. 
Fig.  686,  Cyrtoceras  snbannulatum  D'Orb.  ;  a,  a  transverse  section;  Fig.  687,  Trocholites 
undatus   Hyatt  =  Lituites  undatus  Hall,  from  the   Black   River  limestone,    referred  to 


PALEOZOIC   TIME  —  LOWER    SILURIAN.  515 

Trochoceras  of  Barrande  by  Foord,  and  named  T.  Halli  Emm.  ;  Fig.  688,  Trocholites 
Ammonius  Hall,  from  the  Trenton,  at  Middleville,  N.Y.  Whiteaves  has  described  and 
figured  several  species  of  the  Orthoceras  family  from  Manitoba,  from  the  vicinity  of 
Winnipeg  Lake  and  elsewhere  (1891). 

7.  Worms.  —  Serpulites  dissolutus  B.,  Trenton,  Canada;    Salterella  Billingsi  Saff., 
Tennessee. 

8.  Crustaceans.  —  Fig.  689,  Asaphus  platycephalus  DeKay  ;  Fig.  690,  Calymene  calli- 
cephala  Green ;   Dalmanites  (Phacops)  callicephalus  H. ;  Fig.  691,  Lichas  Trentonensis 
Con.;  L.  cucullus  M.  &  W.,  Illinois;  Fig.  692,  Trinucleus  concentricus  Eaton;  Ceraurus 
pleurexanthemus  Green  ;  Illcenus  crassicauda  Wahl. ,  New  York  and  Illinois  ;  /.  Taurus  H. 
Other  genera  are  Bathyurus,  Triarthrus,  Acidaspis,  Encrinurus,  Harpes,  Proetus. 

Fig.  693,  Leperditia  f abilities  Con.,  New  York,  Canada,  and  Tennessee;  L.  armata 
Wale.  ;  L.  Canadensis  Jones ;  Beyrichia  bella  Wale.,  Trenton  Falls. 

9.  Vertebrates.  —  For  Walcott's  account  of  the  discovery  of  the  remains  of  Fishes  in 
the  Trenton  of  Colorado  see  Bull.  Geol.  3oc.,  iii.,  153,  March  15,  1892.    It  was  announced 
to  the  Biological  Society  of  Washington,  at  a  meeting,  February  7,  1891.     The  remains 
were  first  found  in  the  Harding  sandstone,  near  Harding  quarry,  within  a  mile  of  Canon 
City.    They  also  occur  in  Helena  Canon,  18  miles  to  the  north-northeast.    The  section  at 
the  latter  place,  above  the  Archaean  gneiss,  consists  of  22£'  of  arenaceous  limestone  with 
thin  layers  of  chert,  containing  Upper  Cambrian  fossils ;  51'  of  a  similar  rock,  with  Cal- 
ciferous  species,  of  the  genera  Ophileta,  Straparollus,  etc. ;  101'  of  sandstone  —  the  Hard- 
ing sandstone  —  containing  the  plates  of  Placoderms  and  Lower  Trenton  fossils  ;  110'  of 
massive  arenaceous  limestone  ;  a  thin  band  of  Carboniferous  limestone.    The  section  is 
repeated  many  times  in  the  canons,  removing  all  doubt,  says  Walcott,  as  to  the  strati- 
graphic  position  of  the  Harding  sandstone.     There  are  no  strata  of  the  Upper  Silurian  or 
Devonian  series  at  either  of  the  localities. 

The  characteristic  species  of  the  Galena  limestone  include  Receptaculites  Oweni  H., 
Haly sites  catenulatus,  Lingulela  lowensis  Owen,  Clitambonites  Americanus  Whitf.,  Mur- 
chisonia  major  H.,  Fusispira  ventricosa  H.,  F.  elongata  H.,  Maclurea  cuneata  Whitf.,  M. 
subrotunda  Whitf. 

2.    Utica  and  Hudson  Epochs. 

Figures  representing  the  supposed  terrestrial  plants  described  by  Lesquereux  from 
the  rocks  of  the  Cincinnati  group  near  Cincinnati,  O.,  and  Covington,  Ky.,  are  contained 
on  page  198  of  the  last  edition  of  this  work.  Dr.  Newberry,  after  an  examination  of  the 
specimens,  published  the  same  year  his  opinion  against  them. 

1.  Spongiozoans.  —  Cyathophycus  reticulatus  Wale,  and  C.  subsphericus  Wale,  from 
the  Utica  slate,  Oneida  County,  N.Y.     Trans.  Albany  Inst.,  x.,  18,  1879.     Species  of 
Pasceolus,  Astylospongia,  Microspongia,  Receptaculites,  Brachiospongia. 

2.  Actinozoans.  —  In  the  Hudson  beds,  Favistella  stellata  H.,  Fig.  704  ;  several  species 
of  Columnaria  ;  Cyathophylloids  of  the  genus  Petraia,  as  in  the  Trenton ;  also  of  the  genus 
Zaphrentis,  Z.  Canadensis  B. ;  Halysites  gracilis  H.,  Fig.  705,  from  Green  Bay,  Wis. ; 
Sarcinula?  obsoleta  H.,  Fig.  706;  Tetradium  fibratum  Saff.,  from  Tennessee,  etc.,  Figs. 
707,  707  a  •  T.  cellulosum,  the  Birdseye  species  from  Kentucky. 

3.  Hydrozoans.  —  The  species  of  Graptolites  figured  on  page  510  are  a  few  from  the 
large  numbers  afforded  by  the  Utica  and  Hudson  shales.     The  specimens  for  figures  699, 
Cosnograptus  gracilis,  and  702,  Dicranograptus  ramosus,  besides  others,  were  from  the 
Normanskill  shales  near  Albany.     The  age  of  these  shales  has  been  questioned  by  Lap- 
worth  on  paleontological  grounds  (Trans.  Hoy.  Soc.  Canada,  iv.,  pages  167-172).     The 
New  York  State  geologists  have  considered  the  beds  to  be  equivalent  to  the  Hudson  River, 
or  the  Utica  shales,  or  to  both.  Lapworth  refers  the  Graptolites  to  his  "  Ccenograptus  zone  " 
of  Llandeilo  age,  equivalent  to  the  Black  River  and  Trenton  limestones.     The  same  beds 


516  HISTORICAL   GEOLOGY. 

at  Cincinnati,  holding  Ccenograptus  gracilis  and  three  other  species  of  Normanskill  Grap- 
tolites,  also  contain  Triarthrus  Beckii  and  other  characteristic  Utica  species  (Ulrich,  Am. 
GeoL,  i.). 

4.  Echinoderms.  —  Among  Crinoids,  Fig.   708,    Glyptocrinus   decadactylus  H.,   not 
uncommon  in  New  York,  Ohio,  Kentucky,  and  other  states ;   also  Dendrocrinus    Cin- 
cinnatiensis  Meek,  and  species  of  the  genera  Heterocrinus,  Porocrinus,  Carabocrinus, 
Reteocrinus,   Canistrocrinus,  Stenocrinus,   Ohiocrinus,  locrinus,  Anomalocrinus,    Mero- 
crinus.     Fig.  703  represents  a  large  Star-fish  from  the  blue  limestone  of  Cincinnati,  as 
figured  by  J.  G.  Anthony,  the  original  of  which  was  4  inches  across. 

There  are  also  Cystoids  of  the  genera  Agelacrinites,  Lichenocrinus,  Hemicystites,  all 
sessile  species,  and  in  this  respect  Actinia-like  ;  also  Star-fishes  of  the  genus  Palceaster,  etc. 

5.  Brachiopods.  —  The  figures  of  Brachiopods   on   page   507   are   from   specimens 
obtained  in  the  Cincinnati  beds.    Other  characteristic  species  are  Lingula  quadrata, 
Crania  scabiosa,  Zygospira  modesta. 

6.  Mollusks.  —  (a)  Lamellibranchs.  —  Cypricardites  Sterlingensis  M.  &  W. 

(6)  Gastropods.  —  Murchisonia  Milleri  H.;  Cyrtolites  ornatus  Con.,  near  Fig.  679  ;  C. 
imbricatus  M.  &  W.,  Illinois  ;  C.  carinatus  Miller  and  others  ;  Cyclonema  bilix  Con. ;  C. 
Cincinnatiense  Ulr.,  etc. ;  Pleurotomaria  Ohioensis  H.,  etc. ;  Cyclora  parvula  H. ;  also 
species  of  the  genera  Trochonema,  Helicotoma,  Metoptoma,  etc. 

(c)  Pteropods.  —  Species  of  Tentaculites,  T.  tenuistriatus  M.  &  W.,  and  T.  Oswegoensis 
M.  &  W.,  from  Illinois,  in  the  Cincinnati  group  ;  Theca  parviuscula,  H. ;  Conularia  for- 
mosa  M.  &  D.  ;   C.  Trentonensis  H. 

(d)  Cephalopods.  —  Some  of  the  species,  besides  those  figured,  are  Orthoceras  ampli- 
cameratum  H.  ;    O.  coralliferum  (4  inches  broad)  ;    0.   transversum  Miller ;    Gompho- 
ceras  eos  H.   &  Whitf.,  from  Cincinnati;  Actinoceras  (Ormoceras)  crebriseptum  Hall; 
Endoceras  proteiforme  H. ;  Trocholites  Ammonius. 

7.  Crustaceans.  —  Asaphus  platycephalus  ;  A.  Canadensis  Chapm. 
Ostracoids  occur  of  the  genera  Leperditia,  Cytheropsis,  Beyrichia,  Primitia. 

Some  of  the  genera  and  species  from  the  Cincinnati  beds  are  the  following :  Cceno- 
graptus gracilis  H.,  Fig.  699  ;  Dendrograptus  gracillimus  Lesq. ;  D.  tenuiramosus  Wale.  ; 
Dicranograptus  ramosus  H.,  Fig.  702  ;  Diplograptus  Whitfieldi  H.  ;  D.  spinulosus  H. ; 
Climacograptus  typicalis  H. ;  species  of  Zaphrentis  ;  Inocaulis  arbuscula  Ulv.  ;  the  Tren- 
ton species,  Glyptocrinus  decadactylus;  Heterocrinus  Canadensis;  H.  geniculatus ; 
species  of  Palceaster,  Protaster,  Codaster ;  of  Lingula,  Strophomena,  Orthis,  Rhyncho- 
nella,  Crania  ;  Tellinomya  alta  ;  Fig  709,  Avicula  demissa  ;  Ambonychia  radiata  ;  species 
of  Lyrodesma,  Modiolopsis,  Orthodesma;  Conularia  Trentonensis,  C.  formosa  M.  &  D., 
Fusispira  terebriformis,  Endoceras  proteiforme,  Cyrtoceras  ornatum  ;  Trinucleus  concen- 
tricus,  Calymene  Christyi  H.,  Dalmanites  breviceps  H.,  Proetus  parviusculus  H. ;  species 
of  Primitia,  Beyrichia,  Leperditia,  Cytheropsis. 

In  the  Eureka  district,  Nevada,  according  to  Walcott,  the  Pogonip  limestone,  which 
rests  on  the  Cambrian  and  is  2700'  thick,  contains  in  the  lower  part  a  mixture  of  Potsdam 
and  Silurian  species  ;  the  genera  Dicellocephalus,  Agnostus,  Ptychoparia  being  largely  devel- 
oped, and  some  species  identical  with  Wisconsin  Potsdam  species ;  and  with  these  are 
Acrotreta  gemma  and  some  other  Calciferous  species  ;  but  above  the  middle  of  the  Pogo- 
nip beds  the  characteristic  Cambrian  features  are  absent,  and  there  occur  the  genera 
Heceptaculites,  Monticulipora,  Pleurotomaria,  Maclurea,  Cyphaspis,  Bathyurus  and 
Asaphus ;  and  still  higher  the  genera  Orthis,  Strophomena,  Cyrtolites,  Orthoceras,  Endo- 
ceras, Tellinomya,  Amphion,  Ceraurus,  Asaphus,  Leperditia,  Beyrichia,  which  appear  to 
indicate  the  horizon  of  the  Lower  Trenton,  or  the  Chazy.  Between  the  Pogonip  limestone 
and  the  Devonian  there  are  500'  of  Eureka  quartzyte  and  1800'  of  Lone  Mountain  lime- 
stone, and  only  Halysites  catenulatus  has  been  found  here.  See  Walcott,  U.  S.  G.  8. 
Hep.,  4to,  1884. 


PALEOZOIC   TIME LOWER   SILURIAN. 


517 


720. 


The  fossils  discovered  by  A.  Wing  in  the  Taconic  formation  in  the  limestone  of  cen- 
tral Vermont  were  from  many  localities,  and  were  more  or  less  perfectly  determined  by 
Billings  of  Canada  (Am.  Jour.  Sc.,  xiii.,  1877).  Some  of  them  are  Pleurotomaria  stami- 
nea,  Pleurocystites  tenuiradiatus,  Crinoidal  disks,  and  large  specimens  of  Maclurea  from 
West  Rutland  ;  Trinucleus  concentricus  from  Hubbardton  ;  from  East  Cornwall,  Ste- 
nopora  fibrosa,  S.  Petropolitana,  with  species  of  Orthis, 
Strophomena,  Rhynchonella,  and  Orthoceras,  pronounced 
Trenton  by  Billings  ;  north  and  south  of  East  Cornwall, 
Rhynchonella  beds  containing  pygidia  of  Trilobites,  a  large 
Maclurea,  Bathyurus  Saffordi;  at  Bascom's  Ledge,  3  miles 
west  of  south  of  West  Cornwall,  Asaphus  canalis,  Bathyu- 
rus  conicus,  Maclurea  matutina,  made  Calciferous  by  Bil- 
lings;  east  of  Shoreham,  Bathyurus  extans,  Columnaria 
alveolata,  Trinucleus  concentricus;  in  southern  Bridport, 
Asaphus  canalis,  Bathyuri,  Maclurea  matutina  ;  in  Orwell, 
Petraia  profunda  (?),  Stenopora  fibrosa,  and  8.  Petropo- 
litana, Heceptaculites  Neptuni ;  at  Ellsworth  Ledge,  2  to  3 
miles  west  of  Middlebury,  a  large  Orthoceras,  Bathyurus 
Saffordi,  and  from  higher  beds  B.  Angelini,  Asaphus  canalis, 
Maclurea,  Orthis,  Leperditia,  Crinoidal  stems;  2  miles 
north  of  Middlebury,  the  slightly  curved  Orthoceras,  here 
figured,  natural  size,  having  40  to  52  septa  to  an  inch  (1877); 
and  half  a  mile  to  the  northwest  a  large  Maclurea.  For 
an  account  of  the  discoveries  of  Dwight  and  others,  see 
the  references  already  given,  page  495.  The  discoveries 
of  Walcott  were  among  the  latest,  and  as  they  were 
made  in  the  typical  quartzyte  of  Vermont  almost  down 
to  the  Massachusetts  line,  also  in  the  Eolian  limestone 
just  west,  in  Bennington,  Vt.,  Williamstown,  Mass.,  and 

in  eastern  New  York,  and  in  other  localities  in  western  Vermont  and  eastern  New  York, 
and  thus  covered  all  the  Taconic  formations,  the  demonstration  became  complete  that 
the  Taconic  series  is  simply  a  combination  of  the  Cambrian  and  Lower  Silurian. 

EUROPEAN. 

The   Lower   Silurian   series   of   Great  Britain  comprises,   commencing 
below,  the  following  groups :  — 

1.  The  Arenig   group  (Sedgwick,   1852)  :    slates   and  flaggy  sandstones 
which  rest  comformably  on  the  Tremadoc  slates  of  the  Upper  Cambrian. 
The  beds  occur  in  North  and  South  Wales,  and  have  a  thickness  of  2500 
feet  in  the  latter.     The  stiper  stone  beds  of  Shropshire  are  here  included, 
and  the  upper  part  of  the  Skiddaw  slates.     In  Merionethshire,  North  Wales, 
the  volcanic  rocks  of  this  period  include  a  lower  series  of  ashes  and  con- 
glomerates, in  some  places  3300  feet  thick ;  a  middle  group  of  felstones 
and  porphyries  1500  feet  thick ;  and  an  upper  series  of  fragmental  deposits 
800  feet. 

2.  The  Llandeilo  flags :   sandstones  and  shales  of  Llandeilo  in  Caermar- 
thenshire,  Wales,  where  first  described  by  Murchison  (1834). — In  West- 
moreland  and   Cumberland,  or  the  Lake  District,  the  volcanic  deposits  of 
this  period,  but  beginning  in  the  Arenig  and  continuing  through  the  Bala, 


Orthoceras  primigenium  ? 


518  HISTORICAL   GEOLOGY. 

cover  an  area  of  not  less  than  550  miles  and  have  a  thickness  of  about  8000 
feet ;  the  rocks  are  felsytes,  andesytic  and  other  lavas,  and  volcanic  tufa. 

3.  The  Bala  (Sedgwick,  1838),  or  Caradoc  group  (Murchison,  1839):  con- 
sisting of  shales,  flags,  and  sandstones,  with  some  limestone.  —  The  Caradoc 
rocks  in  Shropshire  are  about  4000  feet  thick,  while  the  Bala,  in  the  Bala 
district,  Merionethshire,  have  a  thickness  of  only  1100  to  1200  feet,  and  the 
chief  limestone  stratum  is  only  20  or  30  feet  thick  near  the  middle.     The 
Coniston  limestone,  the  equivalent  of  the  Bala,  has  a  thickness  of  200  feet. 
The  Upper  Coniston  beds  are  Upper  Silurian. 

In  Caernarvonshire,  northwestern  Wales,  great  eruptions  took  place 
in  this  period,  making  eruptive  accumulations  6000  to  8000  feet  thick.  The 
rocks  are  porphyries,  felsytes,  andesytes,  besides  diabases.  Ireland,  also, 
had  its  eruptions. 

4.  The  Lower  Llandovery  group.     The  beds  have  a  thickness  in  South 
Wales  of  600  to  1000  feet,  but  they  are  absent  from  North  Wales.     They 
consist  of  shales,  flags,  sandstones,  and  conglomerates.     The  Upper  Llando- 
very is  closely  related  to  the  Lower  in  rocks  and  fossils.     The  two  were 
separated,  and  the  former  made  the  base  of  the  Upper  Silurian,  by  Sedgwick 
in  1853,  who  called  them  the  May  Hill  sandstones.     This  arrangement  is 
adopted  by  Geikie. 

The  thickness  of  the  Lower  Silurian  rocks  of  Wales  has  been  estimated 
at  25,000  feet.  But  over  a  fourth  of  this  is  owing  to  volcanic  contributions, 
which,  as  they  are  of  an  extraordinary  source,  should  be  set  aside  in  compar- 
ing the  thickness  of  the  sedimentary  beds  of  different  regions  with  reference 
to  elapsed  time.  In  the  south  of  Scotland  the  thickness  is  over  16,000  feet. 

It  is  not  possible  to  make  out  a  precise  parallelism  between  the  British 
and  American  strata.  Approximately  the  Arenig  group  represents  the  Cal- 
ciferous ;  the  Llandeilo  flags,  the  Chazy;  the  Bala  and  Caradoc,  the  Trenton; 
and  the  Lower  Llandovery,  the  Utica  and  Hudson  beds. 

The  Lower  Silurian  and  Cambrian  formations  of  Norway,  Sweden,  Russia, 
and  Bohemia,  which  rest  upon  Archaean  rocks,  have  but  little  thickness  — 
1000  to  2000  feet ;  and,  adding  what  denudation  may  have  carried  away, 
4000  or  5000  feet  would  be  a  large  estimate  for  the  original  amount. 

In  northern  and  northwestern  France,  or  Normandy  and  Brittany,  Lower 
Silurian  rocks  occur  in  a  much  upturned  condition.  The  gr&s  Armoricain  is 
a  sandstone,  according  to  Barrois,  of  the  age  of  the  Chazy  and  Trenton 
limestones.  Below  it,  and  also  above  it,  are  shales  or  slates,  and  those  above 
may  represent  the  remainder  of  the  Lower  Silurian.  They  are  found,  also,  of 
similar  character  in  the  Asturias,  northern  Spain,  and  in  the  Pyrenees. 

In  Bohemia,  the  Lower  Silurian  of  the  basin  of  the  Prague  is  the  Stage 
D,  or  2d  Fauna,  of  Barrande.  It  consists  of  shales,  with  some  quartzyte  and 
conglomerate  below,  and  has  a  thickness  of  about  3000  feet. 

In  southern  Sweden  (Scania),  the  beds  are  mostly  shales,  many  of  the 
beds  Graptolitic,  with  some  limestone ;  and  are  divided  into  a  Lower,  Middle, 


PALEOZOIC   TIME  —  LOWER    SILURIAN. 


519 


721. 


and  Upper  Group;  and  the  Christiania  district,  a  Lower  Group  of  Grapto- 
litic  shales  with  sandstone,  and  an  Upper,  consisting  largely  of  limestone 
with  some  shales. 

LIFE. 

PLANTS.  —  The  figure  here  given  has  great  interest  on  account  of  its 
representing  a  specimen  of  a  Lower  Silurian  plant  above  the  level  of  a  sea- 
weed. It  is  from  the  Skiddaw  slates.  A.  Nicholson,  the  discoverer,  described 
it  as  a  seaweed  (Buthotrephis  Hark- 
nessi),  and  this  it  may  still  be.  But 
Dawson  refers  it,  with  reason  ap- 
parently, to  the  Marsileacese,  —  at 
present  fresh- water  plants  of  the  higher 
Cryptogams.  As  the  group  of  leaves 
resembles  the  whorl  on  the  stem  of  an 
Equisetum,  he  named  the  genus  Protan- 
milaria,  the  name  implying  a  relation 
to  the  genus  Annularia  of  this  tribe. 

ANIMALS.  —  The  following  are 
figures  of  a  few  other  fossils.  Orthis 
jlabellulum(Fig.  722)  occurs  in  the  Bala 
limestone.  Orthis  elegantula  (Fig.  723) 
ranges  from  the  middle  of  the  Lower 
Silurian  (Coniston  limestone)  to  the 
Wenlock  of  the  Upper  Silurian.  The 
Crania  (Fig.  724)  is  from  the  Bala. 
Asaphus  Powisi  (Fig.  726)  and  Ampyx 
nudus  (Fig.  728)  are  Llandeilo  Trilo- 
bites,  and  Illcenus  Davisi  (Fig.  727) 
occurs  in  the  Bala  limestone. 

Fig.  729  represents  the  telson  or  caudal  segment  and  appendage  of  a  large 
Ceratiocaris,  C.  Angelini,  from  the  upper  member  of  the  Lower  Silurian  in 

722-728. 
726 


Protannularia  Harknessi. 


BRACHIOPODS.  —  Fig.  722,  Orthis  flabellulum  ;  723,  O.  elegantula;  724,  Crania  divaricata.    LAMELLIBBAJSCH. — 
725,  Conocardiuin  dipterum.    TRILOBITES.  — 726,  Asaphus  Powisi ;  727,  Illsenus  Davisi ;  728,  Ampyx  nudus. 

Sweden.     The  length  of  this  Crustacean  in  its  entire  state  must  have  been 
fully  one  foot. 


520 


HISTORICAL    GEOLOGY. 


The  earliest  of  known  fossil  insects  is  from  Graptolitic  slates  in  the  upper 
part  of  the  Lower  Silurian  of  southern  Sweden.  It  is  a  Hemipter,  and  is 
named  by  Moberg  Protocimex  Siluricus  (1892). 


729. 


Telson  of  Ceratiocaris  Angelini,  nat.  size.    Jones  and  Woodward,  '88. 

Characteristic  Species. 

Great  Britain.  — Arenig  group.  — The  Skiddaw  slates  of  the  Arenig  group  abound  in 
Graptolites  of  the  genera  Diplograptus,  Climacograptus,  Didymograptus,  Phyllograptus, 
Dendrograptus,  etc.  Other  prominent  genera  and  species  of  the  group  are  :  Orthis  calli- 
gramma,  Obolella  plicata,  Lingulella  Davisi;  Pleurotomaria,  Ophileta,  Raphistoma  ; 
Bellerophon,  Conularia  Homfrayi,  Orthoceras;  Agnostus,  ^Eglina  grandis,  Ogygia, 
Asaphus  Homfrayi,  Ampyx  Salteri;  also  the  new  genera  Trinucleus,  Ulcenus,  Barrandia, 
Calymene,  Phacops,  Placoparia,  Homolonotus. 

Llandeilo  flags  and  Lower  Bala.  — Graptolites  of  the  same  genera  as  in  the  Arenig; 
also  Halysites  catenulatus,  Monticulipora  favulosa,  Favosites  fibrosus ;  Actinocrinus, 
Echinosphcerites,  Crlyptocrinus,  Palceaster ;  Acrotreta,  Crania,  Leptcena,  Strophomena, 
JKhynchonella  ;  Modiolopsis,  Ctenodonta,  Palcearca,  Pleurorhynchus  (Conocardium), 
Ophileta  compacta,  Murchisonia  bellicincta,  Euomphalus,  Loxonema,  Pleurotomaria; 
Orthoceras,  Endoceras,  Piloceras ;  Ogygia  Buchii,  Asaphus  tyrannus,  A.  Powisi,  Ampyx 
nudus,  Barrandia,  Trinucleus,  Acidaspis  Jamesii,  Lichas,  Ulcenus,  Homalonotus,  Cheiru- 
rus,  Phacops,  Calymene  Blumenbachii,  ^Eglina  mirabilis. 

Bala  beds,  Caradoc  sandstone,  and  Coniston  limestone.  —  Monticulipora  frondosa  M., 
Favosites  fibrosus,  Heliolites-interstinctus,  Halysites  catenulatus,  Cyathophyllum,  Petraia  ; 
Leptcena  rhomboidalis,  Orthis  biforata,  O.  calligramma,  O.  flabellulum,  O.porcata, 
0.  elegantula,  Atrypa  imbricata,  Leptcena  (Plectambonites)  sericea,  Crania  divaricata ; 
Murchisonia,  Holopella,  Trochonema,  Raphistoma,  Cyclonema,  Bellerophon  bilobatus,  B. 
nodosus,  B.  carinatus  (which  three  species  occur  also  in  the  Lower  and  Upper  Lland- 
overy)  ;  Orthoceras  vagans,  0.  annulatum,  O.  Barrandii  (the  three  continuing  into  the 
Lower  Llandovery)  ;  Endoceras,  Lituites,  Cyrtoceras,  Trocholites,  Piloceras;  Ulcenus, 
Phacops,  Cheirurus,  Lichas,  Acidaspis,  Ampyx,  Agnostus,  Harpes,  Remopleurides,  Caly- 
mene Blumenbachii,  C.  Allportiana,  Sphcerexochus  mirus. 

Lower  Llandovery  group.  —  Favosites  fibrosus,  Halysites  catenulatus,  Heliolites  inter- 
stinctus,  Petraia  bina,  Orthis  Bouchardi,  Atrypa,  Meristella  subundata,  StricTclandinia 
lens,  Ehynchonella  tripartita,  Spirifer  plicatellus,  8.  exporrectus,  Strophomena  arenacea, 
Pentamerus  oblongus,  P.  undatus,  P.  globosus  (the  three  occurring  in  the  Lower  and 
Upper  Llandovery)  ;  Ulcenus  Bowmani,  Cheirurus  bimucronatus,  Trinucleus  concen- 
tricus,  Proetus  Girvanensis.  Lower  Silurian  beds  occur  in  the  south  of  Scotland,  and 
also  in  the  northwest  Highlands.  But  in  the  latter  region  there  is  a  striking  resemblance 
in  fossils,  as  pointed  out  by  Salter,  to  forms  in  Canada  and  New  York  —  the  species  includ- 
ing Orthoceras  arcuoliratum,  Orthis  striatula,  Ophileta  compacta,  Murchisonia  gracilis, 
M.  bellicincta,  and  also  species  of  Maclurea,  Eaphistoma,  and  others  of  American  type. 
Moreover,  at  the  same  time,  the  species  of  northwestern  Scotland  differed  from  those  of 
England  and  Wales.  From  these  facts  it  is  evident  that  troughs  with  Archaean  confines 
had  the  same  importance  on  the  British  or  European  border  of  the  Atlantic  as  on  the 
North  American  side.  We  may  conclude  also  that  the  barrier  between  northwestern  Scot- 


PALEOZOIC   TIME  —  LOWER    SILURIAN.  521 

land  and  the  areas  to  the  south  and  southeast,  which  could  have  made  its  fauna  more 
American  than  British,  must  have  had  great  length.  According  to  Etheridge,  the  Lower 
Silurian  of  Great  Britain,  up  to  1885,  had  afforded  161  species  of  Hydrozoans,  47  of 
Actinozoans,  5  of  Crinoids,  23  of  Cystoids,  6  of  Asterioids,  174  of  Brachiopods,  18  of  Bryo- 
zoans,  80  of  Lamellibranchs,  19  of  Pteropods,  67  of  Gastropods,  21  of  Heteropods,  66  of 
Cephalopods,  188  of  Trilobites,  31  of  Entomostracan  and  Phyllopod  Crustaceans;  no 
Eurypterids,  no  Insects,  no  Fishes. 

Scandinavia  and  Russia  adjoining. —  The  area  of  metamorphic  —  mostly  Archaean 
—  rocks  covers,  besides  the  Scandinavian  peninsula,  the  country  to  and  including  the 
White  Sea  and  thence  southwest  to  the  Gulf  of  Finland,  thus  inclosing  entirely  the  Gulf 
of  Bothnia.  The  Cambro-Silurian  borders  this  region  at  the  North  Cape  ;  also  north  of 
St.  Petersburg  and  south  of  this  place  westward  along  the  south  side  of  the  Gulf  of  Fin- 
land to  the  Swedish  islands  of  Gotland  and  Oland  in  the  Baltic,  and  the  adjoining  east 
coast  of  Sweden.  Then,  over  the  interior  of  Scandinavia,  there  is  a  large  area  on  the  west 
side  of  the  mountains  from  above  Trondhjem  to  the  shores  south  of  Bergen  ;  and  east  of 
the  mountains  about  Ostersund  and  Christiania,  and  also  at  some  other  points.  The  beds 
have  in  general  a  thickness  of  from  1000'  to  2000'.  There  are  in  Finland,  Stage  B  (the 
first) ,  Graptolitic  beds  containing  Lingula,  Siphonotreta,  Obolus,  the  limestones  contain- 
ing Megalaspis,  Orthis  (O.  parva},  Orthoceras,  Porambonites,  Asaphus,  Ceraurus,  Ampyx, 
Phacops;  in  Stage  C,  Echinosphcerites,  Orthoceras;  and  above,  Orthis  (O.  lynx},  Poram- 
bonites, Pleurotomaria,  Ceraurus,  Phacops  ;  Stage  D,  with  Strophomena,  Lichas,  Ceraurus, 
Phacops  ( Chasmops)  •  Stage  E,  with  Leptcena  (L.  sericed),  Strophomena  (S.  deltoidea), 
Orthis  (O.  testudinaria~) ,  Phacops,  Encrinurus,  Cybele;  Stage  F,  with  Orthis,  Strophomena 
(S.  expansa},  Bellerophon  (B.  bilobatus},  Phacops,  Ceraurus,  Encrinurus. 

France.  —  The  Armorican  sandstone  of  Brittany  afforded  Lebesconte  and  Barrois: 
3  Trilobites  ;  only  4  Brachiopods,  and  those  of  the  Lingula  family  ;  over  30  Lamellibranchs, 
a  Bucania,  and  3  Ceratiocarids,  —  but  a  poor  representation  of  the  fauna  of  the  period, 
because  of  the  impurity  in  the  waters  which  a  sandstone  formation  indicates.  Barrois 
refers  the  beds  to  the  age  of  the  Chazy  and  Trenton  limestones  of  the  United  States.  The 
Ceratiocarids  include:  Ceratiocaris,  Myocaris  lutsaria  Salter  and  Trigonocaris  Lebes- 
contei  Barrois.  The  Lower  Silurian  rocks  of  Portugal  have  afforded  a  very  large  Trilo- 
bite  of  the  genus  Lichas.  It  is  named  Lichas  (  Uralichas)  Eibeiroi.  The  total  length  is 
estimated  to  be  560  mm.,  and  385  mm.  without  the  caudal  spine,  which  is  175  mm.  long. 
(Corara.  des  Trav.  Geol.  du  Portugal,  Fauna  Silurica,  Lisbon,  1892.)  This  is  the  longest 
Trilobite  described;  it  exceeds  2  feet  in  length.  Paradoxides  regina,  described  by 
Matthew  from  the  Cambrian  of  New  Brunswick,  was  estimated  to  have  a  total  length 
of  450  mm. 

Bohemia.  —  The  Lower  Silurian  of  Bohemia  is  divided  by  Barrande  into  5  sections. 
They  afford  Trilobites  of  the  following  genera.  (The  numbers  in  parentheses  show  in 
which  of  the  5  sections  they  occur ;  and  the  —  and  + ,  that  the  genus  had  species  also  in 
preceding  or  later  time.)  Agnostus  (+ 1,  5),  Acidaspis  (1  to  5+),  ^Eglina  (1  to  5), 
Amphion  (1),  Ampyx  (5  +  *),Areia  (2,  5),  Arethusina  (4  -f  ),  Asaphus  (1  to  5),  Barrandia 
(1),  Bohemilla  (1),  Calymene  (1  to  5  +),  Carmon  (1,  5),  Ceraurus  (1  to  5  +),  Cyphaspis 
(6  -f ),  Dalmanites  (1  to  5),  Dindymine  (1  to  5),  Dionide  (1,  3,  5),  Harpes  (1  +  ),  Har- 
pides  (1),  Homalonotus  (2  to  5),  lUcenus  (1  to  5+),  Lichas  (1,  5+),  Ogygia  (1,  5), 
Phacops  (4,  5-f),  Phillipsia  (5),  Placoparia  (1,  2),  Proetus  (1,  5+),  Remopleurides 
(5),  Sphcerexochus  (5  +),  Telephus  (4,  5),  Trinucleus  (1  to  5),  Triopus  (2). 

In  Asia,  Silurian  beds  of  the  Tibetan  Himalayas,  described  by  Salter  and  Blanford, 
have  a  thickness  of  6000',  and  afford  species  of  Heliolites,  Ptilodictya;  Leptcena,  Stro- 
phomena,  Orthis,  Ctenodonta;  Holopea,  Cyclonema,  Trochonema,  Raphistoma,  Pleuro- 
tomaria,  Murchisonia,  Bellerophon,  Theca;  Orthoceras,  Cyrtoceras,  Lituites ;  Calymene, 
Sphosrexochus,  Lichas,  Ceraurus,  fllcenus,  Asaphus,  but  no  American  or  European  species. 


522  HISTORICAL    GEOLOGY. 

From  western  China,  Richthofen  has  reported  Orthis  calligramma,  Leptcena  (Plectam- 
bonites}  sericea,  Spirifer  radiatus,  Atrypa  reticularis,  Favosites  fibrosus,  Heliolites  inter- 
stinctus,  Haly sites  catenulatus,  etc.  In  southern  Australia,  in  Victoria,  Lower  Silurian 
beds,  made  35,000'  thick  by  Mr.  Selwyn,  have  afforded  various  Graptolites  of  the  common 
Lower  Silurian  genera. 


ECONOMICAL  PRODUCTS  OP  THE  LOWER  SILURIAN  FORMATIONS. 

Lead  Ore,  Galena.  —  The  Galena  limestone  of  Wisconsin  and  the  adjoin- 
ing states  on  the  south  and  west  derives  its  name  from  the  valuable  lead 
deposits  which  it  contains.  Similar  deposits  occnr  in  the  Lower  Silurian 
limestones  of  Missouri  (though  not  at  present  profitable  like  those  of  the  Cam- 
brian and  Subcarboniferous  limestones  of  that  state)  and  also  in  Arkansas. 
The  large  Joplin  mines  of  Missouri  are  in  the  Subcarboniferous.  On  these 
deposits  see  under  "  Veins/'  page  342.  None  of  them,  as  there  stated,  are  of 
Lower  Silurian  origin,  but  of  some  later,  unascertained  date. 

Mineral  Oil  and  Gas.  —  Mineral  oil  and  gas  come  from  the  decomposition 
of  animal  or  vegetable  materials,  when  buried  and  under  close  confinement 
from  the  atmosphere.  The  Trenton  limestone  and  the  Utica  and  Hudson 
shales  have  long  been  known  to  afford  mineral  oil,  especially  since  the  early 
reports  on  the  subject  by  T.  S.  Hunt,  who  rightly  referred  these  substances 
to  organic  materials  buried  in  the  limestone  or  shale  at  the  time  of  their 
formation  (1861,  1866).  The  black  color  of  the  Utica  shale  is  due  to  car- 
bonaceous substances,  and  oil  is  easily  obtained  by  heating ;  and  in  Colling- 
wood,  Canada,  there  were  formerly  works  for  the  purpose,  30  to  36  tons  of 
shale  yielding  250  gallons  of  crude  oil  (at  a  cost  of  about  14  cents  per  gallon) 
—  an  amount  corresponding  to  about  3  per  cent  of  the  rock  (Hunt).  At 
Manitoulin  Islands,  also,  petroleum  was  early  procured  by  boring.  Whitney 
obtained  21  per  cent  from  the  shale  of  Savannah,  111.  ;  11  to  16  per  cent 
from  that  of  Dubuque ;  and  12  to  14  per  cent  from  that  of  Herkimer  County, 
N.Y.  The  oil  has  been  found  in  Orthocerata  at  Pakenham,  Canada,  and  in 
fossil  Corals  at  Watertown,  N.Y. 

The  distillation  process  was  long  since  thrown  aside  in  consequence  of 
the  free  supplies  of  the  liquid  oil  through  Artesian  borings ;  and  among  the 
productive  rocks  are  some  of  the  Lower  Silurian.  The  idea,  now  fully  sub- 
stantiated, that  the  oil  and  gas  are  usually  to  be  obtained  along  anticlinals, 
was  announced  in  1861  by  T.  S.  Hunt,  and  independently  by  E.  B.  Andrews. 

In  Ohio  and  eastern  Indiana  the  Trenton  limestone  affords  both  oil  and 
gas  abundantly,  but  chiefly  the  latter.  The  region  is  within  the  underground 
range  of  the  Cincinnati  anticline,  and  the  principal  Ohio  localities  are  at 
and  near  Findlay,  150  miles  north  of  Cincinnati,  on  the  axial  part  of  a  portion 
of  the  anticline,  where  it  has  a  local  upward  bulge  or  bend;  and  to  this 
upward  bulge  in  the  axis  the  Findlay  region  appears  to  owe  its  gas-confining 
power.  The  borings  descend  1100  to  1200  feet  to  the  Trenton  limestone,  and 
only  15  to  25  feet,  or,  in  some  parts,  50  feet,  into  the  rock,  a  greater  depth 
usually  being  only  sparingly  productive.  The  Findlay  wells  yielded,  in  1886, 


PALEOZOIC   TIME  —  LOWER    SILURIAN.  523 

at  the  rate  of  20  to  25  millions  of  cubic  feet  of  gas  per  day,  and  half  the 
whole  amount  came  from  a  single  well,  the  Karg  well.  One  boring  in  the 
vicinity,  at  Bairdstown,  yielded  4,000,000  cubic  feet  per  day  when  9  feet 
down  in  the  limestone,  and  12,400,000  when  17  feet  down;  and  the  tools 
"  refused  to  descend  deeper,  dancing  in  the  well  like  rubber  balls."  (Orton, 
Rep.  Econ.  G.  Ohio,  1888.) 

The  rock  pressure  in  some  parts  has  been  found  to  equal  650  pounds  to 
the  square  inch :  in  the  Findlay  field  it  is  about  450  pounds ;  in  the  Indiana 
field  about  320  pounds.  Owing  to  the  pressure,  the  gas,  as  it  is  confined  in 
the  Trenton  limestone,  is  greatly  condensed,  —  its  volume,  if  the  pressure 
equals  320  pounds  to  the  square  inch,  being  about  J-th  of  that  after  escape. 

The  productive  limestone,  as  stated  by  Orton,  is  in  all  cases  dolomyte. 
In  the  Findlay  region  the  composition  was  found  to  vary  from  a  ratio,  for  the 
calcium  and  magnesium,  of  1 : 1  to  that  of  2 : 1.  The  marsh  conditions  under 
which  dolomyte  is  formed  are  favorable  for  the  gentle  trituration  or  mace- 
ration of  organic  materials,  and  their  inclusion  in  the  deposits  so  made.  It 
is  found,  also,  by  Professor  Orton,  that  the  limestone  is  porous,  and  is  thus 
enabled  to  contain  the  oil  or  gas.  Since  the  conversion  of  calcyte  to  dolomyte 
causes  a  diminution  in  bulk  of  ^  to  ^  (page  134),  the  pores,  which  are  a 
result  of  the  change,  should  give  the  rock  great  containing  capacity  —  equal, 
says  Orton,  to  the  actual  amount  afforded. 

The  amount  of  marsh  gas  (ordinary  illuminating  gas)  in  the  mineral 
gas  of  Findlay  is  about  92-5  per  cent ;  and  with  this  are  2  per  cent  of  hydro- 
gen, 0-3  of  olefiant  gas,  3-5  t>f  nitrogen,  and  about  0-5  per  cent  each,  of  oxy- 
gen, carbonic  acid,  and  carbonic  oxide,  and  0-2  of  hydrogen  sulphide.  In 
the  region  of  Lima,  Ohio,  the  limestone  yields  oil.  Salt  water,  also,  comes 
up  in  some  borings.  In  the  borings  water  is  excluded  by  tubing.  The  pro- 
duction of  the  wells  is  often  greatly  increased  by  lowering  torpedoes  con- 
taining from  20  to  160  quarts  of  nitro-glycerine  to  the  bottom  of  the  well 
and  exploding  them  by  means  of  a  piece  of  iron  called  a  "  go-devil,"  which 
is  dropped  down  the  hole  and  strikes  a  fulminating  cap  on  the  torpedo.  The 
whole  process  is  termed  "  shooting "  a  well.  The  explosion  shatters  the 
rock  and  opens  fissures.  Thus  the  area  of  supply  is  extended  and  the  yield 
of  oil  or  gas  increased. 

In  Indiana  the  natural  gas  territory  adjoins  the  eastern,  or  Ohio, 
boundary  for  about  65  miles,  and  has  an  average  width  of  50  miles.  The 
porous  layer,  according  to  A.  J.  Phinney,  is  1  to  20  feet  thick,  and  lies 
beneath  a  non-porous  outer  layer  of  the  limestone,  1  to  15  feet  thick ;  and 
the  rock  is  sometimes  so  open-textured  that  air  may  be  freely  blown  through 
it,  and  it  will  absorb  -^  or  even  1  of  its  weight  of  water.  In  1890,  the 
aggregate  daily  flow  of  the  Indiana  gas  wells  was  779,525,000  cubic  feet. 
(Phinney,  U.  S.  G.  S.  Rep.)  The  Trenton  limestone  has  afforded  no  gas  or 
oil  in  Kentucky  or  Pennsylvania. 

Marbles.  —  The  Chazy  affords  black  marble  in  the  vicinity  of  Lake  Cham- 
plain.  The  Taconic  crystalline  limestone  yields  white  and  clouded  statuary 


524  HISTORICAL   GEOLOGY. 

and  ornamental  marble  in  West  Rutland,  Dorset,  Pittsford,  etc.,  Vt. ;  archi- 
tectural marble  in  Lee,  Mass.,  Canaan,  Conn.,  Westchester  County,  N.Y.,  and 
in  Pennsylvania ;  the  Trenton,  a  beautiful  mottled  brown  and  reddish  brown 
marble  in  east  Tennessee  in  Hawkins  County  and  Knox  County  ;  the  lighter 
spots  in  it  are  delicate  Corals  (Monticulipora,  Stenopora,  etc.). 

Iron  ore.  —  The  valuable  iron  ore,  limonite,  occurs  in  great  beds  along  the  junction 
of  the  Lower  Silurian  limestone  and  the  overlying  Hudson  shales  in  all  the  states  on  the 
line  from  Vermont  to  Alabama,  and  in  many  places  it  is  worked  for  the  iron.  But  the 
ore  is  a  result  of  the  decomposition  of  the  rocks  long  subsequent  to  the  Lower  Silurian 
era  (page  126). 

GENERAL  OBSERVATIONS   ON   THE  LOWER  SILURIAN. 

ROCKS. 

It  is  a  point  to  be  noted  that,  during  the  Lower  Silurian,  the  rocks  of  the 
Continental  Interior  over  the  Mississippi  Basin  were  chiefly  limestones; 
and  that  in  the  Trenton  period  the  limestones  extended  in  great  force  to  and 
beyond  the  Appalachian  protaxis.  There  is  no  evidence  of  their  origin  at 
abyssal  depths.  The  beds  were  mostly  made  in  clear  waters  near  the  sur- 
face, as  in  modern  coral  seas,  and  at  moderate  depths,  probably  not  exceeding 
a  few  hundred  feet.  Magnesian  limestones  prevail  below  the  Trenton,  and 
occur  to  some  extent  within  this  formation;  and  such  limestones  (dolo- 
mytes)  are  strong  evidence  of  a  sea-marsh  condition  during  their  origin,  or 
of  shallow  sea-border  flats,  as  explained  on  page  133.  Such  an  origin  also 
explains  that  fine  trituration  of  all  the  calcareous  relics,  which  made  the 
magnesian  limestone  so  generally  unfossiliferous. 

CLIMATE. 

No  proof  that  a  marked  diversity  of  zones  of  climate  prevailed  over  the 
globe  is  observable  in  the  fossils  of  the  Cambrian  period,  or  of  any  part  of 
the  Lower  Silurian  era,  so  far  as  yet  studied.  The  difference  between  the 
polar  regions  and  the  parallel  of  40°  was  probably  not  greater  than  between 
cold  temperate  and  warm  temperate.  It  has  been  inferred  that  some  differ- 
ence in  zonal  temperature  exists  from  the  closer  resemblance  of  fossils  of 
northwestern  Scotland  to  those  of  Canada  (page  572)  than  to  those  of  Eng- 
land, and  the  existence  of  the  Gulf  Stream  of  the  Cambrian  Atlantic  is  sug- 
gested by  G-.  F.  Matthew.  The  following  species,  common  in  the  United 
States,  and  occurring  at  least  as  far  south  as  Tennessee,  have  been  found  in 
the  strata  near  Lake  Winnipeg:  Strophomena  (Rafinesquina)  alternata,  Lep- 
tcena  (Plectambonites)  sericea  (?),  Maclurea  magna,  Raphistoma  lenticulare, 
Calymene  callicephala,  Monticulipora  lycoperdon,  Receptaculites  Neptuni. 

The  mild  temperature  of  the  Arctic  waters  is  evident  from  the  occurrence 
of  the  following  species  on  King  William's  Island,  North  Devon,  and  at 
Depot  Bay,  in  Bellot's  Strait  (lat.  72°,  long.  94°)  :  Monticulipora  lycoper- 
don, Orthoceras  moniliforme  H.,  Receptaculites  Neptuni  De  France,  Actino- 


PALEOZOIC   TIME  —  LOWER   SILURIAN.  525 

ceras  crebriseptum  H.,  besides  Maclurea  arctica  Haughton,  a  species  near  M. 
magna  of  the  Chazy.  Moreover,  the  formation  of  thick  strata  of  limestone 
shows  that  life  like  that  of  the  lower  latitudes  not  only  existed  there,  but 
nourished  in  profusion. 

BIOLOGICAL  PROGRESS. 

1.  General  Progress.  —  During  the  Lower  Silurian  era  progress  in  animal 
life  was  marvelously  great.     Before  it  closed,  nearly  all  the  grander  divisions 
of  marine  invertebrates  were  represented.     And  these  grand  divisions  were 
displayed  under  nearly  all  their  subdivisions.     The  Actinozoans  were  repre- 
sented by  Alcyonoids  and  Madreporids,  as  well  as  by  Cyathophylloids ;  La- 
mellibranchs,  by  Monomyaries,  related  to  the  modern  Avicula  and  Pecten ; 
Heteromyaries,  related   to   Modiola  and   Mytilus ;  Dimyaries,  both  of  the 
Integripallial  section  related  to  Area  and  Nucula,  and  of  the  Sinupallial 
section  related  to  Cypricardia  and  Tellina;  Pteropods,  by  more  types  and 
much   larger  species  than  now  exist;   Gastropods,  by  the  species  of  the 
Trochus  and  Pleurotomaria  types ;  Trilobites,  by  many  new  genera ;  and  in 
addition  there  were  Eurypterids  of  large  size.     Besides  all  these,  there  were 
Fishes,  the  first  of  Vertebrates. 

The  chief  divisions  of  marine  Invertebrates  supposed  to  be  absent  are : 
Crustaceans  above  Entomostracans,  that  is,  the  typical  Tetradecapods  and 
Decapods ;  the  Dibranchs,  or  Squids  and  Cuttles,  among  Cephalopods ;  the 
Echinoids  among  Echinoderms,  and  the  Actinoids,  or  modern  type  of 
Corals,  among  the  Actinozoans.  The  exhibition  of  marine  Invertebrates 
was,  therefore,  very  wide  in  range  and  far  advanced  in  grade.  There  was 
diversity  enough  to  have  afforded  material  for  quite  a  full  work  on  Inverte- 
brate zoology. 

But,  in  addition  to  life  in  the  waters,  there  was  already  life  over  the  land, 
and  life,  also,  that  could  fly,  and  so  bring  the  air  above  the  land  into  new 
service.  The  water-margins  and  moist  places  of  the  growing  continents 
were  green  with  acrogenous  plants  that  gave  promise  of  future  forests. 
Insects,  as  the  one  specimen  reported  proves,  were  common  almost  every- 
where. Hemipters  are  the  so-called  "Bugs"  and  Aphides.  They  are 
incomplete  in  metamorphosis,  like  other  low-grade  Insects,  and,  therefore, 
are  a  kind  that  might  be  among  the  earliest  in  geological  time ;  but  until 
the  discovery  in  1892,  no  fossil  Paleozoic  species  had  been  reported.  It  has 
already  been  remarked  that  terrestrial  animal  species  rarely  become  fossil- 
ized; among  the  rarer  of  these  are  Insects,  and  of  the  rarest  are  Myriapods 
and  Spiders,  and  those  Insects  that  do  not  frequent  water-margins.  Myria- 
pods were  probably  part  of  the  terrestrial  population,  and  perhaps,  but  less 
probably,  Spiders. 

2.  Culmination  of  the  types  of  Graptolites,  Cystoids,  Pteropods,  Trilobites, 
and  Ostracoids.  —  The  Graptolite,  Cystoid,  Pteropod,  Trilobite,  and  Ostracoid 
types  appear  to  have  reached,  in  the  Lower  Silurian  era,  and  passed,  their 
time  of  highest  display. 


526  HISTORICAL    GEOLOGY. 

Barrande,  in  his  review  of  the  Trilobite  Fauna  of  the  Paleozoic,  which 
he  published  in  1871,  made  the  total  number  of  Cambrian  and  Silurian 
species  then  known  1500 ;  and  those  subsequently  introduced,  in  the  Devo- 
nian and  Carboniferous  eras,  about  200.  He  states  that  in  the  Cambrian 
period  the  number  of  species  known  was  252  in  28  genera ;  in  the  Lower 
Silurian,  886  species  in  52  genera,  eight  of  these  genera  being  of  Cam- 
brian origin;  then  in  the  Upper  Silurian  —  his  third  Fauna  —  there  were 
482  species  in  20  genera,  but  only  three  of  these  20  genera  were  of  Upper 
Silurian  origin,  the  rest  already  existing  in  the  Lower  Silurian. 

The  number  of  known  Cambrian  species  of  Trilobites  has  been  increased 
since  1871  by  more  than  200 ;  and  besides,  a  larger  number  of  the  genera  are 
now  known  to  date  from  the  Cambrian.  But  still  Barrande's  conclusion 
remains  right  —  that  the  Lower  Silurian  was  the  era  of  maximum  develop- 
ment of  Trilobites.  In  North  America,  the  Lower  Silurian  beds  add  215 
species  and  30  genera  of  Trilobites ;  the  Upper  Silurian  only  81  species  and 
three  genera ;  and  of  these  three,  two  occur  in  Europe.  The  type  for  awhile 
was  the  highest  of  the  seas ;  but  that  of  Cephalopods,  of  later  introduction, 
had  passed  it  in  size,  grade,  and  power  before  the  Lower  Silurian  era  closed. 
Such  facts  give  strong  characteristics  to  the  Lower  Silurian,  and  exhibit  its 
contrast  to  the  Upper. 

The  Hydrozoans,  Actinozoans,  and  Bryozoans,  which  usually  produce,  by 
multiplication,  compound  groups  of  branching  and  other  forms,  and  show 
thereby  their  low  grade  among  species,  are  rare  fossils  in  the  Cambrian  as 
simple  individuals,  and  are  wholly  unknown  in  compound  groups,  although 
such  groups  are  indicative  of  low  grade,  and  the  Bryozoans  are  the  lowest 
of  the  Molluscoids.  But  in  the  Lower  Silurian  era  the  compound  forms 
after  the  commencement  of  the  Chazy  period  were  common,  and  were  emi- 
nently so  during  the  Trenton  period.  Ulrich  states,  after  an  investigation 
of  the  Bryozoans  of  Minnesota  (a  few  of  his  figures  are  reproduced  on 
page  506),  that  the  contributions  from  them  of  calcareous  material  for  the 
Lower  Silurian  limestones  of  that  state  were  twice  as  great  as  those  from 
the  Brachiopods  (Rep.  L.  Sil  Bry.  Minnesota,  1893). 


UPTURNINGS   AT   THE   CLOSE  OF   THE  LOWER  SILURIAN. 

AMERICAN. 

General  quiet  of  the  Lower  Silurian  era.  —  The  strata  of  the  Lower  Silu- 
rian in  eastern  North  America  appear  to  have  been  laid  down,  one  over 
the  other,  without  intervening  dislocations.  Through  the  era  there  were 
extensive  oscillations  in  the  water  level,  for  this  is  indicated  by  the  varying 
limits  of  the  formations,  as  well  as  by  changes  in  the  kinds  of  rocks ;  and 
the  exposed  beds  of  one  period  probably  suffered  much  by  denudation  before 
the  next  were  deposited.  But  these  oscillations  resulted  in  no  great  upturn- 
ings  of  the  rocks.  The  era  was  one  of  quiet  progress  in  sedimentary 


PALEOZOIC   TIME  —  LOWER    SILURIAN. 


52J 


deposition  from  the  beginning  of  the  Cambrian  to  the  close  of  the  Lower 
Silurian;  and  it  was  a  very  long  era,  possibly  as  long  as  all  time  that 
has  since  elapsed.  Mountain-making  finally  ensued,  producing,  among  its 
effects,  the  Taconic  Mountain  Range  along  western  and  northwestern  New 
England,  and  also  the  Cincinnati  geanticline,  besides  uplifts  in  Nova  Scotia 
and  New  Brunswick.  Moreover,  there  is  probable  evidence  that  the  Taconic 
Range  at  the  north  was  but  one  of  a  series  along  the  Atlantic  border. 

The  Taconic  Range  and  system.  —  Some  account  of  the  Taconic  Range 
has  been  given  on  pages  386,  387.  There  were  great  flexures,  great 
faults,  and  general  metamorphism.  Fig.  730  represents  a  section,  by 
Selwyn,  extending,  near  Quebec,  from  Montmorenci  Falls  on  the  northwest 
and  crossing  the  north  channel  of  the  St.  Lawrence  to  Orleans  Island. 

730. 


N.W.  II  III    S.E. 

Faulted  and  plicated  rocks  from  Montmorenci  Falls  to  the  island  of  Orleans  and  beyond.    Vertical  scale,  500 

feet  =  1  inch  ;  horizontal  scale,  1£  miles  =  1  inch.    Selwyn. 


The  falls  are  to  the  left  at  F,  and  I  marks  the  line  of  one  fault.  To  the 
left  of  this  fault-line  are  Archaean  rocks  overlaid  horizontally  by  50  feet  of 
Trenton  limestone.  To  the  right  of  it  there  are  Lower  Silurian  rocks,  in  a 
plicated  condition,  from  the  Calciferous  and  Chazy  (Quebec  group,  /,  /,  /)  at 
the  bottom,  through  the  Trenton  limestone  (a,  a,  a)  to  the  Utica  and  Hudson 
shales  (c,  c,  c),  the  upper  of  these  rocks  making  the  bottom  of  the  north 
channel  of  the  river.  To  the  right,  at  II,  there  is  a  second  fault,  the  main 
fracture ;  and  at  III,  a  third  fault.  Between  the  two  is  Orleans  Island,  the 
beds  numbered  6  containing  Utica  G-raptolites ;  and  1  to  5,  those  of  the  so- 
called  Levis  formations  of  the  Quebec  group  of  the  age  of  the  Calciferous 
and  Chazy. 

From  this  region  faults  continue  in  a  south-by-west  direction,  through 
Vermont  and  eastern  New  York.  They  are  conspicuous  in  Vermont,  at 
Snake  Mountain,  in  Addison  County,  and  also  south  of  Shoreham,  where  the 
red  sandrock  rests  on  Hudson  shales  (Wing)  ;  and  in  New  York  at  Bald 
Mountain,  and  elsewhere  in  Washington  County,  near  Rhinebeck  on  the 
Hudson,  and  in  Dutchess  County ;  and  also  in  New  Jersey,  a  mile  west  of 
Otisville,  and  at  the  Lehigh  Water  Gap  (G.  H.  Cook). 

Fig.  731  represents  the  fault  at  Snake  Mountain,  as  given  by  A.  Wing 
(1877).  To  the  right  of  F  is  the  south  end  of  the  ridge  of  Cambrian  red 
sandrock,  called  Snake  Mountain ;  to  the  left  are  Lower  Silurian  formations 


•528 


HISTORICAL   GEOLOGY. 


in  an  overthrust  flexure,  with  the  Hudson  slates  (d)  lying  in  the  syncline. 
The  fault  extends  for  many  miles  to  the  north  and  south. 


731. 


a  b  a 

FAULT  AT  SNAKE  MOUNTAIN,  VT.  —  F,  fault ;  a,  Trenton  limestone ;  6,  Chazy  limestone  ;  c,  Cambrian  ;  d,  Hud- 
son shales.    A.  Wing. 

The  great  western  fault  of  eastern  New  York,  as  described  by  Walcott, 
enters  New  York  from  Vermont  in  Hampton,  Washington  County,  and 
extends  south- south  west  to  the  Rensselaer  County  boundary  line,  passing 
through  Argyle  to  Bald  Mountain  in  Greenwich  and  beyond.  In  the  fault, 
as  in  those  of  Vermont,  the  Lower  Cambrian  strata  are  upthrust  westward 
over  the  Silurian.  Fig.  732  represents  a  section  of  Bald  Mountain,  as  viewed 
from  the  south.  According  to  it  the  plane  of  the  fault  dips  at  the  low  angle 

732. 


Section  of  Bald  Mountain,  the  profile  as  seen  from  the  south.      Ch,  Chazy  limestone ;  E,  Calciferous ;  X,  8, 

shales.    Walcott. 

of  25°.  To  the  right  are  the  Cambrian  beds,  and  to  the  left,  the  underlying 
Chazy  and  Calciferous,  and  in  other  localities  the  Trenton  and  Hudson  for- 
mations. Another  similar  fault,  of  like  westward  thrust,  and  on  a  nearly 
parallel  line,  lies  three  to  four  miles  farther  eastward ;  and  a  third,  still  more 
to  the  eastward.  The  amount  of  displacement  at  Bald  Mountain  is  stated 
to  be  between  two  and  three  miles. 

For  a  map  of  the  Taconic  limestone  belts,  as  now  existing  in  part  of 
eastern  New  York  and  the  associated  schists  and  quartzytes  of  western 
Massachusetts  and  Connecticut,  reference  may  be  made  to  a  description  of 
the  region  in  the  author's  papers  of  1880,  1881,  and  1885,  1887.  The  chief 
belts  lie  to  the  west  of  the  Green  Mountain  Archaean  protaxis,  and  continue 
west  of  it  into  eastern  New  York,  and  also,  after  an  interruption,  in  belts 
that  cross  Hudson  River  into  New  Jersey  and  beyond.  The  largest  belt  is 
that  of  Eolian  limestone  (or  marble)  of  Vermont,  and  the  Stockbridge  lime- 
stone of  Berkshire,  Mass,  (so  named  by  E.  Hitchcock),  lying  to  the  eastward 
of  the  main  Taconic  Ridge.  It  passes  by  the  east  side  of  Mount  Washing- 


PALEOZOIC   TIME LOWER,   SILURIAN. 

733. 


529 


LIMESTONE  AREAS 
OF 

DUTCH ESS 
WESTCH  ESTER 

AND 

PUTNAM  COUNTIES 
NEW  YORK 

AN  DOT 
PART  OF 

WESTERN 
CONNECTICUT 

WITH  THE 

ARCH/EAN 

or 
PUTNAM     CO. 

AND  THE 

PALISADE 
TRAP    RANGE, 

0    ....    5  ,    .  10  M. 

a  Limestone  X~  Archaean 
•&k  Palisade  Trap 


'S  MANUAL  —  34 


530 


HISTORICAL  GEOLOGY. 


ton,  in  southwestern  Massachusetts,  into  Canaan  and  Salisbury  in  north- 
western Connecticut. 

The  accompanying  map  (Fig.  733)  illustrates  the  character  and  positions 
of  the  belts  of  limestone  (horizontally  lined  areas),  which  extend  southward 
in  eastern  New  York  and  from  Canaan  and  Salisbury  in  Connecticut.  The 
area  covered  with  V  symbols  is  mainly  Archaean.  It  is  a  continuation  of 
the  New  Jersey  Highlands  (a  part  of  the  protaxis) ;  it  crosses  the  Hudson, 
between  Peekskill  and  Fishkill,  N.Y.  West  of  the  Kent  Belt  of  lime- 
stone there  is  an  area  of  gneiss  and  other  schists  and  some  limestone  of 
Archaean  age,  between  borders  of  Taconic  schists  and  quartzyte.  The  cross- 
lined  area,  west  of  the  Hudson,  is  the  Palisade  belt  of  trap. 

At  the  northeast  corner  of  the  map,  in  Canaan  (a  town  lying  mostly  to 
the  north  of  the  northern  limit  of  the  map),  the  southern  part  of  the  great 
Stockbridge  belt  divides.  The  chief  branch  extends  southwestward  into 
eastern  New  York,  and  then  southward  to  Dykemans,  where  it  ends  against 
the  Archaean,  after  an  interval  of  mica  schist.  Just  west  of  the  Taconic 
Eidge  are  other  belts  of  limestone.  The  first  of  these  is  a  western  portion 
of  the  limestone  belt  of  Stockbridge  and  West  Stockbridge ;  for  the  limestone 
east  of  the  Taconic  Ridge  dips  under  the  schist  of  the  mountain,  and  comes 
again  to  the  surface,  through  a  synclinal  flexure ;  the  character  of  the  syn- 
cline  is  illustrated  for  the  Mount  Washington  region,  in  Fig.  103,  page  105. 

In  further  illustration  of  the  synclines  of  the  Taconic  Range,  Figs.  734, 
735  are  here  introduced.  Fig.  734  represents  the  general  structure  of  Grey- 


734. 


Taconic  synclinal  mountains  of  crystalline  limestone  overlaid  by  mica  or  hydromica  schist.    Fig.  734,  Greylock, 
Emmons.    735,  Mount  Eolus  in  Dorset,  Vt.    Hitchcock. 

lock,  the  Taconic  Mountain  of  northwestern  Massachusetts  (the  blocked 
areas  are  limestone)  ;  and  Fig.  735,  Mount  Eolus,  Vt.,  a  different  phase  of 
the  syncline,  in  which  the  mountain  consists  mainly  of  limestone.  All  the 
western  belts  of  limestone  have  similar  relations  to  the  schists.  On  the 
map  they  are  shown  to  extend  southwestward,  with  one  or  two  interruptions, 
into  and  through  Dutchess  County,  N.Y.,  and  to  and  beyond  the  Hudson 
River,  as  above  stated. 

The  other  narrower  branch,  which  begins  in  southern  Canaan  (just  beyond 
the  north  border  of  the  map),  as  shown  by  Percival,  extends  southward, 
and  passes  Kent.  Farther  eastward,  there  is  still  another  outcrop  of  this 
same  limestone,  owing  to  a  syncline,  in  a  belt  that  passes  by  New  Milford. 
Southward  from  the  extremities  of  these  two  belts  (see  the  map)  a  series 
of  smaller  limestone  belts  is  continued  through  Westchester  County,  N.Y., 


PALEOZOIC  TIME  —  LOWER   SILURIAN.  531 

into  New  York  (or  Manhattan)  Island.  The  limestone,  which  is  everywhere 
crystalline,  or  is  a  marble,  contains  abundantly  the  same  accessory  minerals 
in  southern  Massachusetts  and  Connecticut,  as  in  Westchester  County  and 
New  York  Island ;  namely,  tremolite  and  white  pyroxene.  In  this  respect 
the  Taconic  limestone  is  widely  different  from  the  Archaean  limestones  of 
the  protaxis  in  Massachusetts,  and  of  outcrops  in  the  Kent-Cornwall  Kidge, 
west  of  Kent,  these  being  chondroditic  (p.  67). 

Two  of  the  Westchester  belts,  near  Peekskill,  extend  northward  up  the 
Archaean  Highlands  of  Putnam  County.  They  lie  in  what  were  originally 
valley-depressions  in  the  Archaean,  although  not  valleys  now.  Their  beds 
are  much  upturned,  although  confined  so  closely  by  the  Archaean ;  and  they 
are  metamorphic,  but  of  the  lighter  kind  characterizing  the  corresponding 
beds  on  the  north  border  of  Peekskill.  To  produce  the  upturning,  the 
inclosing  Archaean  rocks  must  have  been  thrust  forward  either  along  frac- 
tures, or  molecularly.  The  metamorphism  apparently  indicates  that  the 
beds  once  had  great  thickness  over  this  part  of  the  Highlands. 

The  Taconic  series  of  rocks,  and  series  of  upturnings,  appear  therefore  to 
extend  all  the  way  from  the  St.  Lawrence  valley  to  New  York  City.  They 
are  situated  mostly  to  the  west  of  the  Archaean  protaxis  ;  but,  in  Canaan,  the 
more  eastern  branch,  described  above,  passes  to  the  eastward  of  it,  leaving  part 
of  the  Archaean  area  on  the  west ;  and  it  is  this  eastern  branch  that  continues 
on  through  Westchester  County.  The  east  and  west  positions  of  part  of  the 
limestone  belts  of  Westchester  County,  just  south  of  the  Archaean  of  Putnam 
County,  indicate  that,  in  the  upturning,  the  schists  and  other  Taconic  rocks 
were  forced  up  against  the  essentially  stable  Archaean  area.  The  T-shaped 
symbols  on  the  map  indicate  the  strike  and  dip  of  the  rocks,  and  show 
that  the  limestone  and  schists,  referred  to  the  Taconic  series,  are  conform- 
able in  strike. 

The  Taconic  upturning  is  known  to  have  occurred  not  later  than  the  close 
of  the  Lower  Silurian  era  from  the  fact  that  Upper  Silurian  rocks  are  not 
present  in  the  series,  but  actually  overlie  the  Lower  unconformably  in  some 
localities;  as  at  Becrafts  Mountain,  near  Hudson,  N.  Y. ;  on  St.  Helens  Island 
and  Beloeil  Mountain,  near  Montreal,  where  the  Lower  Helderberg  beds  cover 
unconformably  Lower  Silurian  slates ;  and  near  Lake  Memphremagog,  where 
the  Niagara  limestone  occurs  with  its  characteristic  fossils,  and  also  beds  of 
Devonian  Corals.  Again,  on  the  eastern  side  of  the  Green  Mountains,  in  the 
Connecticut  valley,  there  are  unconformable  Devonian  beds  at  Bernardston, 
Mass.,  and  Upper  Silurian  at  Littleton,  N.H.  The  earlier  of  the  formations 
of  the  Upper  Silurian  are  very  thin  in  the  eastern  part  of  the  state  of  New 
York,  and  this  is  apparently  owing  to  the  previous  emergence  of  the  Green 
Mountain  area,  shallowing  the  waters  to  the  eastward.  The  schists,  which 
are  argillyte  and  hydromica  schist  in  Vermont,  are  mica  schist,  chlorite  schist, 
and  gneiss  in  Massachusetts,  and  coarser  mica  schist  and  gneiss  in  West- 
Chester  County. 

The  probability  that  the  upturning  was  continued  southward  through 


532 


HISTORICAL   GEOLOGY. 


736. 


Virginia  has  been  sustained  by  the  discovery,  in  1892,  of  Crinoids,  by  N.  H. 
Darton,  in  the  slate  quarries  of  Arvon,  Buckingham  County,  Va.  A  figure 
of  one  of  the  species  is  here  given  from  Darton's  paper.  Walcott  states 

that  the  species  are  allied  to  those  of  the  genera 
Schizocrinus,  Heterocrinus,  and  Poteriocrinus, 
and  are  of  either  Trenton  or  Hudson  age.  It 
will  be  seen  on  a  map  that  the  Westchester 
belt  and  the  Buckingham  County  locality  are 
so  related  in  position  that  the  latter  may  have 
been  a  part  of  a  long  Westchester  Taconic 
Eange,  which  passed  just  west  of  Philadelphia 
and  Baltimore,  and  may  have  included  South 
Mountain,  Pa.,  and  other  ridges  beyond,  to  the 
east  of  the  protaxis,  —  the  Appalachian  Range 
being  to  the  west  of  the  same.  This  would 
make  the  Taconic  Range  of  western  New  Eng- 
land one  in  a  great  Taconic  system  of  mountain 
ranges. 

Eruptive  rocks. —  Rocks  that  came  up  melted, 
probably  at  the  time  of  the  Taconic  disturbance, 
exist  south  of  Peekskill,  N.Y.,  spread  widely 
over  much  of  Cortland  County,  and  also  occur 
on  Stony  Point  on  the  opposite  (west)  side  of 
the  Hudson  River.  The  rocks  cut  through 
Lower  Silurian  limestones,  and  hence  are  not 
from  the  crystalline  dates  of  f  n  ejection;  but  they  may  be. of  much 

Buckingham  County,  Va.     Darton,  '92.  J  J  J 

later  origin.     They  are  rocks  of  unusual  kinds, 

being  noryte,  chrysolitic  hornblendyte  and  pyroxenyte,  coarse  dioryte,  and 
a  granite-like  rock  in  which  the  feldspar  is  oligoclase.  The  rocks  were 
described  by  the  author  in  1880,  1881,  and  by  G-.  H.  Williams  in  1886.  The 
long  strips  of  schist  and  limestone  in  the  igneous  rocks  appear  to  prove,  as 
the  author  stated  in  his  paper,  that  these  eruptive  rocks  are  partly  or  wholly 
metamorphic-igneous,  produced  by  the  fusion  of  Cambrian  or  Lower  Silurian 
rocks  during  the  period  of  upturning  and  metamorphism.  A  dike  cutting 
through  the  Hudson  beds  of  the  Blue  Mountains,  of  west  New  Jersey,  near 
Beemerville,  is  probably  of  the  same  age.  The  Beemerville  rock  also  is  a 
rare  kind  —  an  Elseolite-syenyte  (B.  K.  Emerson,  1882).  Many  "trap  dikes" 
cut  through  the  Taconic  formation  in  the  vicinity  of  Lake  Champlain  which 
may  be  of  cotemporaneous  origin  (Kemp  and  Masters,  1893). 

The  Cincinnati  geanticline.  —  Cotemporaneously  with  the  disturbances 
above  described  the  low  geanticline  was  formed,  called  the  Cincinnati  uplift 
(page  537),  making  two  islands,  one  over  part  of  Ohio,  eastern  Indiana  and 
Kentucky,  and  the  other  over  Tennessee,  as  reported  by  Safford,  Newberry, 
and  Orton.  The  general  course  of  the  upward  bend  of  the  crust  was  north- 


PALEOZOIC    TIME LOWEK    SILURIAN.  533 

easterly,  nearly  parallel  with  the  Appalachians.  But  at  the  north,  in  Ohio, 
it  extends  northwesterly,  and  has  also  a  northeastern  branch  in  the  direction 
of  Findlay,  Ohio,  toward  Lake  Erie.  That  this  was  the  time  of  the  uplift  is 
proved  by  the  absence  of  Upper  Silurian  and  Lower  Devonian  beds  over  the 
region,  these  formations  thinning  out  toward  the  axis,  where  the  Cincinnati 
limestone  is  the  surface  rock ;  and,  in  Tennessee,  as  Safford  states,  by  the 
Devonian  black  slate  resting  directly  on  the  Lower  Silurian  beds.  The  line 
of  the  axis  presents  now  no  conspicuous  topographical  feature;  but  the 
direction  of  the  draining  streams,  which  follow  the  strike  of  the  strata  on 
either  side,  indicates  that  it  once  formed  a  watershed  that  gave  the  initial 
bearing  to  their  flow.  The  part  of  the  arch  about  Cincinnati  has  been  more 
deeply  and  extensively  removed  than  farther  north,  though  higher  now  than 
elsewhere,  and,  therefore,  "  this  probably  was  originally  the  highest  part  of 
the  arch  within  the  limits  of  the  state  of  Ohio." 

According  to  K.  Bell,  of  the  Canada  survey,  the  geanticline  is  continued 
northward  across  the  west  end  of  Lake  Ontario  to  Lambton,  in  Ontario, 
Canada,  and  perhaps  beneath  Lake  Huron,  but  its  emergence  to  this  distance 
is  not  proved.  This  range  of  broad  islands  and  shallows  had  great  influence 
on  the  rock-making  of  later  Paleozoic  time  —  a  view  first  recognized  by 
James  Hall  in  1859  (Pal.  N.  Y.,  iii.). 

Upturnings  in  Nova  Scotia  and  New  Brunswick.  —  Unconformability 
between  the  Upper  Silurian  and  Lower  Silurian  rocks  has  been  observed 
in  Carleton  County,  N.B.,  just  north  of  the  boundary  near  Metapedia  Lake, 
and  also  on  Lake  Temiscouata,  and  elsewhere  (L.  W.  Bailey);  and  in  Nova 
Scotia  at  Cape  St.  George,  Arisaig,  Lochaber,  and  from  Kerrowgane  down 
the  East  Kiver  of  Pictou,  and  north  of  Sunderland  Lake. 

But  through  this  epoch  there  was  comparative  quiet  north  of  Gaspe  in 
the  northern  part  of  the  St.  Lawrence  Gulf ;  for  the  great  limestone  forma- 
tion of  Anticosti,  which  was  begun  in  the  Lower  Silurian  era,  continued  its 
unbroken  progress  through  the  whole  prolonged  era  of  revolution,  and  after- 
wards far  into  the  Upper  Silurian  era. 

EUROPEAN. 

In  America  the  disturbances  closing  the  Lower  Silurian  were  confined  to 
regions  of  very  thick  depositions,  and  mountain-making  was  the  final  result 
of  the  upturning.  Over  central  New  York  and  farther  west  in  the  Conti- 
nental Interior,  the  beds  of  the  Lower  and  Upper  Silurian  eras  follow  one 
another  without  any  marked  unconformability.  Cases  of  intervening  erosion 
may  be  found;  for  every  period  loses  by  erosion  a  large  part  of  its  depo- 
sitions in  the  supply  of  material  for  the  beds  of  the  following  period ;  but  no 
case  occurs  of  horizontal  deposition  on  upturned  Lower  Silurian  strata. 

In  Europe  the  facts  are  similar.  Over  the  Continental  Interior  of  Europe, 
which  includes  all  European  Russia  up  to  the  Archaean  mountains  on  either 
side,  and  the  surface  south  to  the  foot  hills  of  the  Alps,  the  Upper  Silurian 
beds  lie  conformably  on  the  Lower  Silurian.  The  cases  of  unconformability 


534  HISTORICAL  GEOLOGY. 

are  found  in  western  England  and  Wales,  where  the  strata  claim  a  thickness 
exceeding  20,000  feet  independently  of  ash-ejections.  The  Upper  Lland- 
overy  and  other  Upper  Silurian  beds  rest  upon  the  upturned  edges  of  the 
Lower  Llandovery,  Caradoc,  or  other  inferior  strata.  ">In  one  district, 
between  the  Longmynd  and  Wenlock  Edge,  the  base  of  the  Upper  Silurian 
rocks  is  found  within  a  few  miles  to  pass  from  the  Caradoc  group  across  to 
the  Lower  Cambrian  rocks."  (Geikie,  p.  672.) 

Another  remarkable  region  of  disturbance  is  that  of  the  northwest 
Highlands  of  Scotland,  along  the  chain  of  mountains  between  Eriboll  and 
Ullapool.  For  some  distance  east  of  this  region,  according  to  the  investi- 
gations of  Hicks,  Lapworth,  Peach,  Home,  and  others,  the  Silurian  and 
Cambrian  rocks,  which  overlie  the  Archaean,  are  much  plicated,  and  the 
plications,  on  nearing  it,  become  overthrust  flexures,  often  flexure-faulted, 
with  the  thrust  westward.  Then  commences  over  the  wide  region  a  series 
of  nearly  horizontal  thrust-planes  of  great  extent,  along  which  the  Archaean 
and  overlying  formations  are  thrust  westward,  in  some  places  for  ten  miles. 

Besides  minor  shovings,  there  are  three  maximum  thrust-planes  which 
overlap  so  as  to  carry  the  formations  over  one  another,  pile  them  to  a  great 
thickness,  and  produce  a  series  of  extensive  unconformabilities  between 
Archaean,  Cambrian,  and  Lower  Silurian  terranes ;  and  undisturbed  Lower 
Silurian  limestone  is  often  the  base  of  the  pile,  with  Archaean  rocks  above. 
The  thrust-planes  look  like  planes  of  bedding,  and  were  long  so  considered. 
Under  the  enormous  amount  of  friction  along  the  lower  thrust-plane,  the 
materials  at  the  bottom  of  the  moving  mass  were  sometimes  folded  over  and 
curved  under  it  as  well  as  abraded  or  crushed ;  and,  in  addition,  through  the 
aid  of  the  heat  generated,  sheets  of  sericite  schist  were  made  along  the  plane 
out  of  the  abraded  feldspar,  and  layers  of  other  foliated  metamorphic  rock 
out  of  other  material,  —  the  strike  of  the  foliation  being  more  or  less 
parallel  with  that  of  the  thrust-plane. 

In  some  cases  the  softer  pebbles  of  a  Cambrian  conglomerate  (made  of 
pebbles  of  quartz,  gneiss,  dioryte,  granite)  are  drawn  out  so  as  to  form 
"thin  lenticular  bands  of  mica  or  hornblende  schist  flowing  round  the 
harder  pebbles  of  quartz-rock  "  ;  and  at  one  place  Cambrian  sandstones  have 
been  converted  into  schists  containing  mica,  and  quartzytes  merge  into 
quartzose  sericite  schists.  The  fossiliferous  Silurian  limestones  below  the 
thrust-plane  are  not  generally  altered,  but  in  some  places  have  been  ren- 
dered crystalline.  (Q.  J.  G.  Soc.,  1884, 1888,  the  latter  giving  full  references 
to  earlier  writers  on  the  subject.) 

In  northern  Ireland,  where  the  Lower  Silurian  and  Cambrian  beds  have 
a  thickness  of  more  than  7000  feet,  there  are  evidences  of  metamorphism  in 
portions  of  the  beds,  while  others  still  retain  their  fossils,  and  mark  their 
Siluro-Cambrian  age.  The  Upper  Silurian  beds  above  are  undisturbed  and 
unaltered.  Geikie  states  that  the  crystalline  schists  of  the  Scottish  High- 
lands are  prolonged  over  northern  Ireland  to  Galway  Bay,  which  makes  the 
disturbed  region  400  miles  long. 


PALEOZOIC   TIME  —  UPPER    SILURIAN.  535 

The  Ural  Mountains  include  long  ranges  of  upturned  and  more  or  less 
crystalline  Lower  Silurian  rocks,  but  it  remains  undetermined  whether  or  not 
there  is  unconformability  with  the  Upper  Silurian  beds. 

Of  the  204  species  of  fossils  in  68  genera,  found  in  the  Lower  Lland- 
overy  beds,  104  species  in  45  genera  still  exist  in  the  Upper  Llandovery. 
(Etheridge.) 

NEOPALEOZOIC   SECTION. 

In  contrast  with  the  EOPALEOZOIC  part  of  geological  history,  when  vast 
continental  seas  prevailed,  —  a  condition  well  styled  thalassic,1  both  as 
regards  geography  and  life,  —  the  NEOPALEOZOIC  was  the  time  of  the  in- 
creasing emergence  of  the  land  over  large  areas,  and  the  emergence  also  of 
life  in  various  forms,  until  in  eastern  North  America  a  great  semi-continent 
existed,  over  1000  miles  wide,  which  was  covered  with  grand  forests  and 
other  vegetation,  and  populated  by  Amphibians  and  Reptiles  of  ancient 
kinds,  and  by  the  largest  of  Insects,  besides  other  inferior  terrestrial 
Invertebrates. 

UPPER  SILURIAN  ERA. 

SYNONYMY.  —  Upper  Silurian,  Murchison,  Phil.  Mag.,  vii.,  July,  1835;  Hep.  Brit. 
Assoc.,  Aug.,  1835;  Silur.  System,  1838.  Upper  part  of  Silurian,  Sedgwick,  Rep.  Brit. 
Assoc.,  1835;  Proc.  G.  Soc.,  1838;  Q.  J.  G.  Soc.,  Jan.,  1846.  Silurian,  Sedgwick, 
Q.  J.  G.  Soc.,  147,  1852  (the  Lower  Silurian  being  made  Upper  Cambrian);  Lapworth, 
G.  Mag.,  1879,  p.  13  ;  H.  B.  Woodward,  Geol.  Eng.  and  Wales,  1887.  Murchisonian,  D'Or- 
bigny,  Pal.  et  Geol.,  ii.,  301,  1851.  Bohemien,  A.  de  Lapparent,  Tr.  de  Geol.,  1883. 

NORTH  AMERICAN. 

J 
SUBDIVISIONS. 

(  3.  Upper  Pentamerus  epoch. 
3.  Lower  Helderberg    U   Shaiy  limestone  epoch. 

Period.  (  ^    Lower  Pentamerus  epoch. 

2.  Onondaga  Period.  —  Salina  beds,  Water-lime,  Tentaculite  limestone. 

(  3.  Niagara  epoch.     Shale  and  limestone. 
1.  Niagara  Period.       •<  2.  Clinton  epoch.     Clinton  group. 

(  1.  Medina  epoch.     Oneida  and  Medina  beds. 

The  map  on  page  536  (Eig.  737)  presents  a  general  idea  of  the  dry 
land  of  North  America  at  the  opening  of  the  Upper  Silurian.  The  shore  line 
of  the  time  was  not  far  outside  of  the  Archaean  limits  (indicated  by  the 
dotted  line),  showing  that  the  growth  of  the  continent  had  been  mainly 
along  its  Archaean  borders.  There  was  an  extension  of  the  land  over  the 

1  With  Homer,  the  Qd\aff<ra  was  the  great  Interior  Continental  Sea,  the  Mediterranean,  while 
the  outside  waters  around  the  land  were  called  'ft/cecils.  The  term  thalassic  is  used  above  in 
the  Homeric  sense. 


536 


HISTORICAL  GEOLOGY. 


region  of  Wisconsin,  on  the  borders  of  New  York  and  Canada,  and  about  the 
Adirondacks.  The  Taconic  Eange  had  just  been  made,  and  probably  a 
Taconic  system,  consisting  of  ranges  from  Canada  to  Georgia ;  and  as  a  part 
of  the  uplifting,  the  eastern  portion  of  New  York  became  emerged,  and  also 
a  large  area  along  the  Atlantic,  south  of  New  York.  (The  Archaean  limits 
in  the  latter  area  are  not  marked,  because  not  yet  denned.)  Western  North 
America  was  not  notably  changed. 

The  upward  movements,  moreover,  closed  against  the  sea  the  broad  St. 
Lawrence  channel.     This  channel  had  been  in  earlier  time  a  great  highway 

737. 


North  America  at  the  opening  of  the  Upper  Silurian. 


for  tides  and  currents,  and  what  they  could  transport  between  the  Atlantic 
and  the  Continental  Interior.  But  now  the  Interior  Sea  had  to  depend  for 
rock-making  material  on  what  could  be  gathered  from  its  borders  and  the 
stony  secretions  of  aquatic  life.  But  it  left  open  the  northeastern  troughs, 
east  of  the  Green  Mountains  and  St.  Lawrence  —  the  Connecticut  valley 
trough,  the  Gaspe- Worcester,  and  the  Acadian,  or  that  from  western  New- 
foundland to  Narragansett  Bay,  over  the  Bay  of  Fundy  and  Massachusetts 
Bay;  for  these  have  severally  their  Upper  Silurian  and  later  rock  forma- 
tions. It  is  even  probable  that  the  Gaspe- Worcester  trough  had  its  eastern 
Archaean  confine,  which  separated  it  from  the  Acadian  trough,  extended 


PALEOZOIC    TIME  —  UPPER    SILURIAN.  537 

northeastward  across  the  present  Gulf  of  St.  Lawrence  to  Newfoundland; 
for  it  has  been  shown  by  Canadian  geologists  that  the  Upper  Silurian  fossils 
within  the  Acadian  trough  in  Nova  Scotia  are  not  all  of  American  type,  but 
have  many  relations  to  those  of  Great  Britain,  much  closer  relations  than 
the  fossils  of  the  island  of  Anticosti.  The  fact  would  put  Anticosti  within 
the  Gaspe-Worcester  trough.  But  such  a  confine  could  not  have  been  an 
uninterrupted  barrier,  since  the  troughs  of  the  Connecticut  valley  and  Gaspe'- 
Worcester  belt  must  have  had  tidal  connection  with  the  Atlantic. 

The  two  large  islands  of  the  Cincinnati  uplift  are  those  marked  C  and  T. 
They  partially  divide  off  from  the  great  Continental  Interior  a  portion  called 
the  Eastern  Interior  Sea,  which  from  this  time  onward  was  like  a  great  bay, 
having  a  narrow  southwest  opening  over  Alabama,  a  length  of  about  700 
miles,  and  its  northern  limits  near  the  sites  of  Albany  and  Troy.  Its  waters 
communicated,  in  the  Upper  Silurian  era,  with  those  of  the  Central  Interior 
Sea,  over  Michigan  and  northern  Ohio.  But  this  connection  was  diminished 
during  the  progress  of  Paleozoic  time.  It  had  probably,  also,  a  shallow 
connection  with  the  Atlantic  over  Pennsylvania  and  Maryland,  where  the 
land  is  now  low,  permitting  of  an  interchange  of  water  and  life. 

The  conditions  of  this  Eastern  Interior  Sea  influenced  not  only  its  tides 
and  currents,  but  also  the  temperature  and  purity  of  the  waters,  the  supply 
of  sediments,  the  kinds  of  life,  and  hence  in  various  ways  modified  rock- 
making  and  biological  distribution.  And  this  influence  was  all  the  more 
profound  that  the  eastern  part  of  the  great  bay  was  within  the  limits  of  the 
slowly  deepening  Appalachian'trough,  or  geosyncline,  in  which  thick  deposits 
were  in  progress  for  the  future  Appalachian  Range. 

West  of  the  Mississippi  there  was  another  island,  that  of  Missouri. 
Probably  Upper  Silurian  beds  exist  to  the  south  of  it,  according  to  recent 
observations  by  H.  S.  Williams.  But  farther  southwest  ward,  over  much  of 
Arkansas  and  over  Texas,  to  the  Pecos  (E.  T.  Hill),  Upper  Silurian  and 
Devonian  beds  are  absent ;  and  it  is  probable  that  a  large  area  of  dry  land 
here  existed.  Its  limits,  however,  are  so  uncertain  that  it  is  not  indicated 
on  the  map.  Moreover,  Silurian  and  Devonian  beds  have  not  yet  been 
reported  from  Mexico,  and  the  Carboniferous  are  the  only  Paleozoic  beds. 

The  dry  land  of  the  continent  was  small,  and  hence  there  were  only  small 
streams  for  the  supply  of  sediments.  Among  them  an  embryo  Hudson  River 
brought  down  Adirondack  waters  and  detritus  to  the  head  of  the  Eastern 
Interior  Sea,  near  Albany,  and  an  embryo  Mississippi  and  a  St.  Lawrence 
drained  other  Archaean  areas. 

The  rock-making  of  the  period  was  confined,  so  far  as  has  been  ascer- 
tained, to  the  Interior  Continental  Sea  and  the  troughs  or  channels  of  New 
England  and  eastern  Canada.  These  troughs  are  those  of  Archaean  origin, 
already  reported:  commencing  to  the  eastward,  the  Acadian,  the  Gasps- 
Worcester,  the  Connecticut  valley,  and,  during  the  later  part  of  the  period 
only,  the  Hudson-Cham  plain  trough.  No  Upper  Silurian  beds  are  known 
along  the  Atlantic  border  south  of  New  York. 


538  HISTORICAL   GEOLOGY. 

The  conditions  described  and  illustrated  on  the  map  make  it  apparent 
that  the  Interior  Continental  Sea  opened  westward  toward  the  Pacific,  but 
not  eastward  over  temperate  latitudes  toward  the  Atlantic ;  and  hence  that 
migrations  to  those  seas  from  Eurasia  should  have  been  chiefly  from  the 
west  rather  than  from  the  east.  On  the  contrary,  New  England  and  eastern 
Canada  remained  still  open  toward  the  Atlantic  and  Europe,  and  hence  dif- 
ferences in  the  cotemporaneous  faunas  of  this  eastern  part  of  North  America 
and  of  the  Continental  Interior  should  be  expected. 


1.  NIAGARA  PERIOD. 
ROCKS  — KINDS  AND  DISTRIBUTION. 

The  beds  over  New  York  referred  to  the  Medina  epoch  —  the  earlier  part 
of  the  Niagara  period  —  include,  to  the  eastward,  a  seashore  formation,  called 
the  Oneida  conglomerate  from  Oneida  in  central  New  York,  and  an  off- 
shore sand-flat  formation,  called  the  Medina  sandstone  from  Medina  in  the 
western  part  of  the  state. 

The  Oneida  conglomerate  is  a  hard  light-gray  rock  made  of  quartz 
pebbles  and  sand.  It  covers  large  areas  in  Oneida  and  Herkimer  counties, 
N.Y.,  but  thins  out  eastward  to  15  to  20  feet  at  Rondout  on  the  Hudson. 
It  comes  up  again  in  Ulster  County  (southeastern  New  York),  owing  to  an 
uplift  along  the  Shawangunk  (pronounced  Shong-gum)  Mountains,  and  is 
there  called  the  Shawangunk  grit.  This  range  commences  near  the  Hudson, 
southwest  of  Kingston,  and  to  the  southwest,  between  New  Jersey  and  Penn- 
sylvania, becomes  the  Kittatinny  Mountains.  The  grit  makes  the  crest  and 
southwest  front  of  these  mountains,  and  the  beds  dip  westward  30°-40°. 
Thence  the  conglomerate,  or  grit,  stretches  on  southwestward  through  Penn- 
sylvania into  Virginia,  where  "  it  makes  the  bony  axis  of  the  principal  Appa- 
lachian ridges'7  (Rogers),  and  beyond  into  east  Tennessee,  where  it  is  the 
Clinch  Mountain  sandstone  of  Safford.  In  Ulster  County,  N.Y.,  near  Red- 
bridge,  the  Shawangunk  grit  has  afforded  galena  and  copper  pyrites  in  large 
masses,  and  fine  crystals;  but  the  mine  is  not  now  worked.  The  Medina 
sandstone  is  ordinarily  a  gray  to  red  mottled  sandstone,  fine-grained,  thin- 
bedded,  somewhat  argillaceous,  especially  so  to  the  westward,  and  bears 
evidence  of  having  originated  as  a  great  sand-flat  formation  in  shallow  waters, 
as  first  described  by  Hall;  for  its  layers  are  often  covered  .with  ripple- 
marks,  wave-marks,  and  rill-marks,  evidences  of  exposure  above  the  waters, 
perhaps  with  the  retreat  of  the  tide,  and  in  many  places  of  gentle  wave 
action  on  a  slightly  inclined  beach.  In  making  the  rill-marks  (page  95), 
the  retreating  undertow  swept  past  worn  shells  of  Lingula  cuneata  or  small 
pebbles  in  the  surface  sands  of  the  beach. 

The  beds  are  not  found  in  eastern  New  York  near  the  Hudson,  but 
mainly  to  the  west  of  Oneida  County.  They  border  Lake  Ontario  to  its  west- 
ern extremity,  and  constitute  the  lower  half  of  the  Niagara  bluffs  at  Lew- 


PALEOZOIC   TIME UPPER    SILURIAN.  539 

iston.  Thence  they  continue  westward  through  Ontario  with  a  thickness  of 
300  to  400  feet,  and  in  eastern  Ohio  thin  out  to  10  to  150  feet  of  reddish 
shale  (as  found  in  deep  borings)  resting  on  Hudson  or  Utica  shales.  They 
are  not  found  in  Michigan.  To  the  southward,  in  New  York,  the  formation 
disappears  beneath  the  later  beds ;  but  it  reappears  on  the  west  slope  of  the 
Kittatinny  Mountains,  and  outcrops  to  the  southwest  in  east  central  Penn- 
sylvania, Virginia,  and  eastern  Tennessee. 

The  thickness  of  the  Shawangunk  grit  is  500  feet  in  New  York,  and  700 
to  800  feet  in  Pennsylvania ;  and  that  of  the  Medina  beds,  in  the  latter  state, 
1800  feet. 

The  beds  thus  give  an  idea  of  the  seashore  work  of  the  period.  They 
also  indicate  the  generally  shallow  depths  of  the  Eastern  Interior  Sea,  but 
nothing  as  to  the  condition  of  the  seas  over  the  rest  of  the  continent. 

The  Clinton  group  has  a  wide  distribution.  Its  beds  occur  in  central  and 
western  New  York  (the  group  taking  its  name  from  Clinton  in  Oneida 
County),  in  Pennsylvania,  Ohio,  Indiana,  Wisconsin,  eastern  Tennessee, 
Kentucky,  Alabama,  and  Georgia.  The  Cincinnati  geanticline,  which  put 
above  the  surface  the  Lower  Silurian  rocks,  accounts  for  the  absence  of  the 
Clinton  not  only  from  part  of  Ohio,  but  also  from  western  Kentucky  and 
Tennessee.  In  New  York  and  Pennsylvania  the  rock  is  mainly  a  shaly  sand- 
stone and  shale  of  rough,  irregular  aspect,  with  some  intercalated  limestone ; 
on  the  Niagara  Kiver  it  is  about  half  limestone ;  and  in  Ohio  and  farther 
west  almost  wholly  limestone. 

A  peculiar  feature  of  the  formation  is  the  occurrence  in  many  regions  of 
one  to  three  beds,  1  to  10  feet  thick,  of  argillaceous  red  iron  ore  (hematite), 
usually  ooly  tic,  with  the  grains  round  or  flattened.  The  grains  are  often  con- 
centric in  structure,  proving  them  to  be  true  concretions,  like  those  of  an 
ordinary  oolyte,  and  of  sea-margin  origin.  (C.  H.  Smyth,  from  observations 
near  Clinton,  N.Y.,  and  elsewhere  in  1892.) 

These  ore-beds  accompany  the  Clinton  formation  from  New  York  to  Ala- 
bama, through  Pennsylvania,  Virginia,  eastern  Kentucky,  and  Tennessee, 
and  also  occur  in  Wisconsin.  They  are  usually  fossiliferous,  and  the  ore  is 
sometimes  called  the  "  red  fossil  ore."  The  fossils  are  broken,  and  include 
stems  of  Crinoids,  Bryozoans  in  small  fragments,  and  other  species.  The 
beds  were  evidently  made  over  tide-washed,  salt-water  flats,  where  tritura- 
tion  was  gentle.  They  indicate  a  wonderful  degree  of  uniformity  in  conti- 
nental level  over  a  wide  area. 

Clinton  fossils  occur  with  those  of  the  Niagara  at  some  points  along  the 
Atlantic  border  of  Maine,  from  the  boundary  of  New  Brunswick  to  Penob- 
scot  Bay.  They  are  found  also  in  Nova  Scotia,  and  on  Anticosti  several 
hundred  feet  of  limestone  are  referred  to  the  Clinton. 

The  Niagara  formation  is  still  more  widely  spread  than  the  Clinton, 
though  far  from  continental  in  its  distribution.  In  most  regions  it  is  a  thick 
limestone,  but  in  New  York  and  other  parts  of  the  Eastern  Interior  Sea,  the 
lower  portion  is  shale,  indicating  a  gradual  transition  in  rock-making  condi- 


540  HISTORICAL  GEOLOGY. 

tions  from  those  of  the  Clinton  epoch.  The  limestone  is  largely  a  coral-made 
rock,  and  thereby  indicates  clear  seas  during  the  time  of  its  formation.  In 
Iowa  and  some  other  parts  of  the  West,  it  abounds  in  chert  or  hornstone, 
which  is  usually  in  layers  coincident  with  the  bedding,  like  flint  in  chalk ; 
and  the  fossils  are  all  siliceous.  At  Lockport,  N.Y.,  cavities  in  the  lime- 
stone afford  fine  crystallizations  of  dog-tooth  spar  (calcite)  and  pearl-spar 
(dolomite),  with  gypsum,  and  occasionally  celestite,  and  still  more  rarely  a 
crystal  of  fluor. 

In  New  York,  the  beds  reach  quite  to  the  Hudson  Eiver,  and  are  there 
distinguished  as  the  Coralline  limestone ;  they  are,  however,  but  a  few  yards 
in  thickness.  They  spread  westward  through  New  York,  making  250  feet  of 
the  height  of  the  Niagara  bluffs ;  continue  beyond  through  Ontario,  in  Can- 
ada, with  a  thickness  of  250  to  300  feet,  to  Lake  Huron,  west  of  Georgian. 
Bay,  and  to  the  Manitoulin  Islands ;  extend  around  the  north  side  of  Lake 
Michigan  to  Illinois,  Wisconsin,  northeastern  Iowa,  and  the  adjoining  part 
of  Minnesota  —  making  in  all  a  distance  from  east  to  west  of  1000  miles. 

The  Niagara  is  stated  to  be  absent  south  of  New  York,  from  the  eastern 
half  of  Pennsylvania  (where  Lower  Helderberg  beds  rest  on  Clinton),  and 
from  the  larger  part  of  West  Virginia.  It  is  absent  also  from  eastern 
Tennessee  and  part  of  southern  Ohio,  owing  to  the  Cincinnati  geanticline ; 
but  occurs  in  western  Tennessee,  along  Tennessee  Kiver,  and  in  northern. 
Kentucky  ;  and  also  in  Missouri,  and  in  northern  Arkansas,  as  a  continuation, 
probably  of  the  area  of  central  and  southwestern  Illinois. 

In  western  New  York,  the  lower  third  of  the  rock  is  usually  shale,  the 
other  two  thirds  limestone.  It  is  prominent  on  the  Genesee  River  at  Koch- 
ester,  N.Y.,  and  also  at  Lockport,  where  its  geodes  gave  it  early  the  name  of 
the  "  Geodiferous  "  limestone.  At  Niagara  Falls,  directly  at  the  fall,  the 
limestone  makes  the  upper  85  feet,  and  the  shale  the  lower  80  feet,  as  illus- 
trated in  the  following  section,  Fig.  738,  from  Hall.  In  the  section,  Nos. 

738. 


Section  along  the  Niagara,  from  the  Falls  at  F  (south)  to  Lewiston  Heights  at  L  (north) ;  W,  the  whirlpool ; 
Nos.  1,  3,  5,  7,  are  shales,  and  6,  8,  limestones.     Hall. 

7,  8,  are  the  Niagara,  the  greatest  thickness  of  which  is  165  feet ;  below  it,  as 
is  seen  in  the  bluff,  at  Lewiston  Heights  (L),  lie  the  Medina  beds,  1,  2,  and 
the  Clinton,  3  to  6.  The  recession  of  the  fall  is  slowly  going  on,  because  of 
the  undermining  of  the  limestone  by  the  wearing  out  of  the  shale. 

In  Ohio,  the  limestone,  300  feet  thick  with  10  to  100  feet  of  shale  below, 
outcrops  as  a  belt  around  the  area  of  the  Cincinnati  geanticline. 


PALEOZOIC   TIME  —  UPPER    S1LUKIAN.  541 

In  Illinois,  the  limestone  underlies  the  city  of  Chicago  and  constitutes 
the  gray  "  Athens  Marble  "  and  the  gray  and  buff  "  Joliet "  building-stone. 
In  the  Mississippi  valley  it  often  contains  flint  or  chert  in  nodules  and  is 
dolomyte.  In  Wisconsin,  it  has  distinctly  the  features,  in  some  places,  of  an 
old  coral-reef.  Forty  species  of  Corals  have  been  described  from  it.  Some 
large  coral  masses  "  stand  erect  in  the  rock,  precisely  as  they  grew,"  making 
up,  along  with  fragments  and  sand  derived  from  broken  corals,  shells,  and 
Crinoids,  the  coral  reef-like  limestone  bed.  Between  and  about  what  look 
like  true  barrier  reefs,  there  are  accumulations  of  coral  fragments,  becoming 
finer  and  finer  on  receding  from  the  reef,  and  thus  the  rock  graduates  into 
ordinary  limestone.  (Chamberlin.) 

In  New  England,  the  St.  Lawrence  Bay  of  the  Niagara  period  extended 
far  south  along  the  Connecticut  valley ;  for  Niagara  beds,  with  their  fossils, 
occur  at  Littleton,  N.H.,  resting  unconformably  on  older  beds.  They  occur 
also  in  northern  Maine  and  New  Brunswick ;  and  on  the  coast  of  Maine  in 
Penobscot  Bay,  near  Machiasport,  in  Cobscook  Bay;  along  the  Acadian 
trough;  they  exist  also  in  Nova  Scotia.  In  Anticosti,  a  thick  limestone 
ranges  continuously  from  the  Hudson  to  the  Clinton  groups. 

The  Rocky  Mountain  region  has  few  outcrops  of  Upper  Silurian  rocks. 
The  Niagara  beds  have  been  observed  in  the  Black  Hills  of  South  Dakota, 
near  Deadwood,  but  not  in  the  Wasatch  Mountains ;  and  they  have  not  been 
identified  in  Arizona  at  the  Colorado  Canon,  nor  over  the  Great  Basin.  They 
are  doubtfully  identified  in  the  Eureka  district,  Nevada,  in  the  upper  part  of 
a  limestone  stratum  which  is  Trenton  at  base  —  a  Halysites  occurring  in  the 
beds.  The  formation  has  a  wide  range  in  Arctic  seas,  and  occurs  on  some 
islands  in  Hudson  Bay. 

Mineral  oil  exists  in  large  quantities  in  the  Niagara  limestone  at  Chicago, 
though  not  capable  of  being  collected  to  advantage.  Worthen  says  that 
a  portion  of  the  limestone  is  "  completely  saturated  with  oil." 

The  distribution  of  the  rocks  of  the  Niagara  period  sustains  the  conclu- 
sions presented  on  a  preceding  page  with  regard  to  American  geography  at 
the  opening  of  the  Upper  Silurian.  They  show  that  the  waters  over  the 
state  of  New  York  shallowed  toward  the  Hudson  River,  and  thickened  west- 
ward, thus  according. with  other  evidence  as  to  the  emergence  of  the  Green 
Mountain  region  in  connection  with  the  making  of  the  Taconic  Mountains. 
The  shallowing  was  toward  the  emerged  mountain  belt.  They  prove  also, 
through  the  abundant  arenaceous  deposits,  that  while  in  the  earlier  part  of 
the  period  the  region  of  the  Eastern  Interior  Sea  was  shallow,  at  a  later  date 
deeper  and  clearer  seas  prevailed,  even  from  Hudson  River  to  and  beyond  the 
Mississippi,  in  which  Corals  and  Crinoids  were  growing  abundantly ;  yet  they 
were  not  necessarily  deep  seas,  since  150  feet  of  depth  is  enough  for  all  the 
work  of  the  modern  reef-making  Polyps. 

1.  MEDINA  GROUP.  —  The  Oneida  conglomerate  is  a  thick-bedded  formation,  and  the 
rock  so  hard  as  to  stand  out  boldly  in  rocky  ledges  and  ridges.  The  Shawangunk  grit  was 


542  HISTORICAL  GEOLOGY. 

the  "millstone  grit"  of  Eaton.  It  was  formerly  much  used  for  making  the  "  Esopus 
millstones,"  so  named  from  Esopus,  an  early  name  of  Kingston ;  and  at  Ellenville,  for 
glass-making.  It  is  intersected  by  quartz  veins ;  and  mines  of  lead  and  zinc  have  been 
worked  in  it  at  Ellenville,  Wurtsborough,  and  elsewhere,  which  have  yielded  remarkable 
geodes  of  quartz  crystals,  with  crystals  of  lead  ore  (galena),  sphalerite,  chalcopyrite,  and 
other  minerals. 

The  Medina  sandstone,  where  fullest  developed  in  New  York,  includes,  according 
to  Hall,  four  divisions,  as  follows :  — 

(4)  Red  marl  or  shale  and  shaly  sandstone,  resembling  No.  2,  below ;  banded  and 
spotted  with  red  and  green. 

(3)  Flagstone,  — a  gray,  laminated  quartzose  sandstone,  called  "  gray  band." 

(2)  Argillaceous  sandstone  and  shale,  red,  or  mottled  with  red  and  gray. 

(1)  Greenish  gray  sandstone,  graduating  below  into  the  Oneida  conglomerate,  the 
"  gray  band  "  of  Eaton. 

In  the  Genesee  section  (page  91),  the  strata  1  and  2  correspond  to  the  Medina;  3,  4, 
5,  6,  to  the  Clinton  group  ;  and  7,  8,  to  the  Niagara  shales  and  limestone. 

In  Canada  the  Medina  beds,  besides  existing  in  Ontario,  occur  south  of  the  St.  Law- 
rence, over  a  few  areas  east  and  northeast  of  Lake  St.  Peter. 

The  Oneida  conglomerate  disappears  before  reaching  the  southern  border  of  Pennsyl- 
vania, and  the  passage  from  Hudson  into  the  red  Medina  is  imperceptible.  Hudson  fossils 
continue  far  up  into  the  Medina  in  Bedford  County.  (Hep.  T2,  Penn.  Surv.,  pp.  91  and 
92,  J.  J.  Stevenson.)  This  condition  becomes  more  striking  in  southwest  Virginia  beyond 
the  New  River,  where  Hudson  forms  occur  up  to  within  100'  of  the  white  Medina.  (J.  J. 
Stevenson,  Proc.  Amer.  Phil.  Soc.,  xxiv.,  85,  87,  94 ;  and  xxii.,  142,  150.)  A  peculiarity 
of  the  Upper  or  white  Medina  in  Pennsylvania  and  southward  is,  that  exposure  to  atmos- 
phere polishes  it ;  all  other  sandstones  there  are  roughened  by  exposure.  (J.  J.  S.) 

2.  CLINTON  GROUP.  —  This  is  the  "Protean  group"  of  the  JV.  Y.  Annual  Geological 
Reports  of  1836-1840.  The  sandstone  of  the  Clinton  epoch  in  New  York  is  often  quite 
hard  ;  and  much  of  it  has  the  surface  uneven  from  knobby  and  vermiform  prominences, 
some  of  which  are  attributed  to  Fucoids. 

(a)  Interior  Continental  basin.  —  On  the  Genesee  River,  at  the  falls  near  Rochester, 
the  Clinton  group  consists  of:  (1)  24'  of  green  shale,  of  which  the  lower  part  is  shaly 
sandstone  and  the  upper  part  an  iron-ore  bed ;  (2)  14'  of  limestone,  called  Pentamerus 
limestone,  from  a  characteristic  fossil;  (3)  24'  of  green  shale;  (4)  18£'  of  limestone, 
called  the  Upper  limestone. 

On  the  Niagara  (see  section,  Fig.  738,  page  540)  there  is  shale  4',  without  the  iron  ore, 
overlaid  by  limestone  25',  the  limestone  corresponding  to  the  three  upper  divisions,  and 
its  upper  20'  to  the  upper  limestone.  To  the  eastward,  in  Oneida,  Herkimer,  and  Mont- 
gomery counties,  the  rock  is  100'-200'  thick,  and  includes  no  limestone,  though  partly 
calcareous.  The  group  consists  of  shale  and  hard  grit  or  sandstone,  in  two  or  more  alter- 
nations, along  with  two  beds  of  the  iron  ore.  Near  Canajoharie — which  is  not  far  from 
its  eastern  limit  —  the  formation  has  a  thickness  of  50'.  In  Starkville,  Herkimer  County, 
the  rock  contains  a  bed  of  gypsum. 

North  of  Lake  Huron,  the  Clinton  beds  occur  along  the  Manitoulin  Islands,  Drummond 
Island,  and  20  miles  to  the  westward. 

(6)  Appalachian  region.  —  The  relations  of  the  Clinton  of  Pennsylvania  and  the 
country  southward  to  that  of  central  New  York  are  not  determined  in  detail.  The  rocks 
in  Pennsylvania  are  shales,  olive  to  almost  black,  with  some  sandstones  and  beds  of  calca- 
reous iron  ore.  The  series  is  persistent,  northwestwardly,  to  the  last  exposures,  almost  at 
the  easterly  foot  of  the  Alleghany  Mountains.  Its  subdivisions  are  :  (1)  Reddish  to  olive 
shales,  100'  to  700' ;  (2)  iron  sandstone,  5'  to  50' ;  (3)  shales,  200'  to  675' ;  (4)  iron 
sandstone,  10'  to  20' ;  (5)  shales  with  calcareous  layers,  100'.  The  whole  thickness  is 
from  900'  to  1000'.  A  commingling  of  Clinton  and  Niagara  forms  occurs  in  the  upper 


PALEOZOIC   TIME  —  UPPER   SILURIAN.  543 

portion  of  the  column.  In  Virginia  the  Clinton  consists  of  sandstones  and  shales,  mostly 
sandy,  having  an  estimated  thickness  of  not  far  from  850'.  Beds  of  fossil  or  calcareous 
ore  are  present  from  central  Pennsylvania  to  Alabama.  (J.  J.  S.) 

In  east  Tennessee  the  rocks  are  200'  to  300'  thick,  and  include  one  or  two  beds  of  the 
oolitic  iron  ore. 

In  western  Kentucky  the  oolitic  red  ore  beds  occur  in  Montgomery,  Bath,  and 
Fleming  counties  and  along  Pine  Mountain. 

(c)  Eastern  Border  region.  —  In  Nova  Scotia,  at  Arisaig,  which  is  within  the  Acadian 
trough,  the  rocks  are  shales  and  limestone,  and  have  a  thickness  of  about  500'.  At  the 
East  Kiver  of  Pictou,  there  are  also  slates  and  calcareous  bands,  probably  of  the  same 
age.  They  include  a  deposit  of  oolitic  iron  ore,  like  that  of  the  Clinton  rocks  of  central 
New  York,  which  in  some  places  has  a  thickness  of  40'.  In  southern  New  Brunswick  the 
beds  are  like  the  Arisaig. 

The  fossiliferous  Upper  Silurian  rocks  of  the  coast  of  Maine,  on  the  borders  of  the 
same  Acadian  trough,  are  described  in  Hitchcock's  Eeport  on  Maine,  1861,  and  in  papers 
by  W.  O.  Crosby,  Am.  Jour.  Sc.,  xxiii.,  1862  ;  N.  S.  Shaler,  ib.,  xxxii.,  1886 ;  Dodge  and 
Beecher,  ib.,  xliii.,  1892.  See  also  Foerste,  on  the  iron  ore,  t&.,  xli.,  1891 ;  and  Smyth,  on 
the  same,  ib.,  xliii.,  1892. 

3.  NIAGARA  GROUP.  —  (a)  Interior  Continental  basin.  —  At  Rochester,  N.Y.,  there 
are  about  80'  of  limestone,  overlying  80'  of  shale ;  and  the  limestone  makes  nearly  the 
whole  height  of  the  upper  fall.  At  Lockport  there  is  a  fine  exhibition  of  the  rock,  and  it 
includes  an  "encrinital"  layer,  which  is  mottled  with  red,  and  over  it  a  bed  full  of  deli- 
cate Corals.  The  limestone  in  some  places  breaks  vertically  into  small  columns,  and  such 
specimens  have  been  called  Stylolites.  The  structure  is  due,  as  explained  by  Marsh,  to  a 
slipping,  through  vertical  pressure,  of  a  part  capped  by  a  fossil  shell  against  an  adjoining 
part  not  so  capped.  Such  Stylolites  occur  in  limestones  of  other  periods  from  the  Cam- 
brian to  the  Carboniferous. 

The  "  Coralline  limestone  "  is  only  4'  thick  at  the  base  of  the  Helderberg  Mountains  ; 
but  at  Nearpass's  quarry,  south  of  Port  Jervis,  it  is  50'  thick,  and  contains  numerous 
Niagara  fossils. 

The  Guelph  limestone  (a  dolomyte),  well  seen  at  Gait  and  Guelph,  in  Ontario,  western 
Canada,  and  farther  west  (formerly  supposed  to  be  of  the  age  of  the  Salina  beds),  is  the 
upper  part  of  the  Niagara  limestone.  The  thickness  in  Ontario  is  about  160'. 

The  Niagara  limestone  and  shale  extend  through  Ohio  and  Indiana  to  Wisconsin  and 
Iowa.  But  it  is  wanting  in  southern  Illinois.  The  "Clear  Creek  limestone"  of  Union, 
Jackson,  and  Alexander  counties  is  probably  Lower  Helderberg  (Worthen).  The  rock 
has  a  wide  distribution  in  Iowa  (where  it  is  in  part  the  Leclaire  limestone) .  Much  of  it 
is  cherty,  and  has  the  fossils  silicified.  An  analysis,  by  J.  D.  Whitney,  of  a  specimen  from 
Makoqueta  County,  Iowa,  obtained  calcium  carbonate  52-18,  magnesium  carbonate  42-64, 
with  0-35  of  sodium  carbonate,  traces  of  potash,  iron  carbonate,  and  sulphuric  acid,  0-63 
of  alumina  and  iron  sesquioxide,  and  4-00  insoluble  in  acid.  The  beds  form  the  summits 
of  some  of  the  mounds,  as  Table  Mound,  near  Dubuque. 

In  west  Tennessee  the  Meniscus  limestone,  150'  to  200'  thick,  noted  for  its  fossil 
sponges,  of  which  one  is  meniscus-shaped,  is  probably  the  equivalent  of  the  Niagara 
limestone. 

The  Niagara  beds  of  the  Black  Hills,  near  Deadwood,  were  identified  through  their 
fossils,  by  C.  E.  Beecher.  In  the  Deadwood  section  there  are  Cambrian  beds  below,  rest- 
ing on  Archaean ;  above,  there  is  the  Carboniferous  limestone,  with  probably  Devonian 
strata  between. 

(&)  Appalachian  region.  —  The  Niagara  has  not  been  recognized  distinctly  in  Penn- 
sylvania ;  though  in  the  central  and  southern  portion  of  the  state  there  occurs,  at  varying 
distances  above  the  uppermost  bed  of  iron  ore,  a  succession  of  very  thin  limestones,  which, 
in  many  localities,  contain  Niagara  forms.  This  has  been  placed  by  Lesley  in  the  lower 


544 


HISTORICAL   GEOLOGY. 


division  of  the  Salina.     The  thickness  of  the  shale  and  limestone  varies  from  150'  to  235'. 
(J.  J.  S.) 

(c)  Eastern  Border  region. — The  Niagara  limestone  occurs  in  eastern  Canada,  some 
distance  south  of  the  St.  Lawrence,  being  part,  according  to  Logan,  of  an  extensive  for- 
mation, which  stretches  from  northern  Vermont,  eastward  over  a  part  of  northern  New 
Hampshire  and  northern  Maine,  to  Cape  Gaspe  on  St.  Lawrence  Bay,  as  limestone  with 
some  massive  and  shaly  sandstone.    The  formation  embraces  also  the  strata  of  the  Lower 
Helderberg,  and  possibly  part  of  those  of  the  Lower  Devonian.     Niagara  fossils  occur  ia 
the  lower  part  of  the  Gasp6  limestone,  as  well  as  at  some  intermediate  points.    They 
have  been  found  also  near  Penobscot  Bay. 

At  Arisaig,  in  Nova  Scotia,  there  are  shales  of  the  Niagara  epoch,  1300'  thick ;  and 
they  occur  also  in  New  Canaan  and  Pictou. 

(d)  Arctic  regions.  —  In  the  Arctic,  the  Niagara  limestone  has  been  observed  between 
the  parallels  of  72°  and  76°,  on  the  shores  of   Wellington  and  Barrow  straits,  and  on 
King  William's  Island.     The  common  chain  coral  Halysites  catenulatus  has  been  found 
at  several  localities,  along  with  various  Upper  Silurian  species,  and  also  at  other  places 
between  79°  and  82°  N. 


739-743. 

742 


LIFE. 

1.  Plants. 

Supposed  Algae  or  Fucoids,  of  branching  form,  of  the  genus  Buthotrephis, 
occur  in  the  Clinton  group.  They  are  various  rounded  casts  looking  like 
those  of  stems,  or  groups  of  stems,  some  of  which  are  probably  tracks  of 
marine  animals,  as  already  explained. 

2.  Animals. 

In  the  Niagara  series  no  evidence  of  fresh-water  or  terrestrial  species  of 
plants  or  animals  has  yet  been  observed.     Aquatic  Vertebrates  or  Fishes 
have  been  reported  from  the  Clinton  beds. 

The  Medina  beds  contain  few  fossils.  These  are 
chiefly  Brachiopods  and  Lamellibranchs,  with  rarely 
Gastropods  and  Cephalopods  among  Mollusks.  Tracks 
of  Sea-worms  are  common,  because  the  beds  are  of  mud- 
flat  and  sand-flat  origin.  The  Clinton  group  has  more 
numerous  fossils,  of  the  same  general  character,  and 
partly  the  same  species;  but  as  it  includes  limestone 
beds,  there  are  also  Polyp-corals,  Bryozoans,  and  Trilo- 
bites.  The  Niagara  beds,  which  were  largely  formed  in 
clear,  open  seas,  contain  a  profusion  of  fossils  of  marine 
types :  Bryozoans,  Polyp-corals,  Crinoids  of  various 
MEDINA.— rig.  739,  Linguia  forms,  Brachiopods  in  great  numbers,  and  various  kinds 
cuneata;  740,  Modioiopsis  of  Mollusks,  with  many  small  and  large  Trilobites. 
^"^ple'um  The  most  common  of  Medina  Brachiopods  is  the 
ittorea;  748,  Bucania  triio-  Lingula  cuneata,  Fig.  739,  a  wedge-shaped  species, 
uta.  Hail.  Figg>  740  and  741  represent  Lamellibranchs ;  and  742, 

743,  Gastropods,  the  last  a  Bucania. 


PALEOZOIC    TIME  —  UPPER    SILURIAN. 


545 


Tracks,  probably  of  a  Sea-worm,  are  represented  by  Fig.  744.  These  tracks 
cover  large  surfaces  of  the  Medina  sandstone,  and  are  occasionally  found  in 
the  Oneida  conglomerate.  They  are  simply  impressions,  the  material  being 


745. 


744. 


Fig.  744,  Harlania  Kalli ;  745,  Cruziana  (Kusophycus)  bilobata  (x  2).    Hall. 

sandstone,  and  without  structure  internally,  except  the  occasional  occurrence 
of  parallel  or  concentric  layers,  due  to  deposition  in  the  depressions.  Fig. 
745  represents  another  form  of  track  supposed  to  be  of  Molluscan  origin. 

The  following  figures  represent  Corals,  a  Bryozoan,  and  a  Graptolite  of 
the  Clinton  group:  — Figs.  746,  747,  one  of  the  common  Cyathophylloid  Corals 


74C 


749 


750 


CORALS,  GRAPTOLITE,  BRYOZOAN.  — Figs.  746,  747,  Zaphrentis  bilateralis  ;  748,  a,  Palaeocyclus  rotuloides;  749,  a. 
Monticulipora ;  750,'a,  Graptolithus  Clintonensis.    Hall. 

of  the  genus  Zaphrentis,  the  latter  a  view  from  above ;  748,  a  small  disk- 
shaped  Coral;  749,  a  minutely  columnar  coral-shaped  Bryozoan  of  the  genus 
Monticulipora;  750,  a  Graptolite;  750  a,  an  enlarged  view  of  the  same. 

Other  Clinton  fossils  are  shown  in  Figs.  751-760.  A  finely  reticulate 
Bryozoan  of  the  genus  Fenestella  (Fig.  751)  is  represented  enlarged  in 
751  a.  Fig.  752  is  that  of  the  characteristic  Brachiopod,  Pentamerus 
oblongus,  and  opposite  views  of  the  hinge  end  of  the  cast  of  the  interior 
are  given  in  Figs.  753,  753  a.  Figs.  754,  a  represent  the  Brachiopod, 
DANA'S  MANUAL  —  35 


546 


HISTORICAL   GEOLOGY. 


Atrypa  reticularis,  which  continues  on  through  the  Devonian;  Fig.  756,  a 
Chonetes  —  a  genus  of  the  Productus  family.  There  were  also  species  of 
Orthoceras. 

Besides  these,   Figs.  759,  760  represent  tracks   probably  of   Mollusks. 
The   Cruziana  (Rusophychus),  called   also   Bilobites  (Fig.  745),  is  a  large 


751-760. 


^ilpiPs 

iw 

Isis^ 

Iff  Ipf  - 

'SSI: 

m 


MOLLUSKS.  —  Figs.  751,  a,  Fenestella  prisca ;  752,  Pentamerus  oblongus ;  753,  a,  part  of  casts  of  the  interior; 
754,  a,  Atrypa  reticularis ;  755,  o,  Hyattella  congesta ;  756,  Chonetes  cornutus  ;  757,  Avicula  rhomboidea ; 
758,  Cyclonema  cancellatuin  ;  759,  track  of  a  Lamellibranch  (x£) ;  760,  track  of  an  Annelid  ?  (x£).  Hall. 

species,  the  figure  being  reduced  one  half;  other  related  kinds  from  the 
Clinton  are  narrower,  and  six  to  eight  inches  long. 

The  Cephalopods  include  Orthoceras  desideratum;  also  species  of  the 
genus  Discosorus  of  Hall,  near  Actinoceras  in  its  broad  beaded  siphuncle, 
but  having  a  shorter  shell,  more  rapidly  tapering  and  slightly  curved ;  the 
species  D.  conoideus  extends  into  the  Niagara  epoch. 

Trilobites  occur  of  the  genera  Calymene,  Dalmanites,  Ceraurus,  Illcenus, 
Homalonotus  and  others,  and  some  kinds  are  identical  with  Niagara  species. 

The  remains  of  Fishes,  reported  from  the  Clinton  beds  of  Pennsylvania, 
are  a  small  portion  of  a  spine  referred  to  a  Shark,  named  by  Claypole  Onchus 
Clintonif  together  with  fragments  of  what  appear  to  be  fish  scales  and  plates. 
The  spines  from  British  Upper  Silurian  beds,  on  which  the  genus  Onchus 
was  established,  are  now  regarded  as  portions  of  the  telsons  of  species  of 
Ceratiocaris ;  and  the  American  may  be  of  similar  relations,  but  this  is  not 
deemed  probable.  See  under  the  Onondaga  period,  page  556. 

Remains  of  a  Fish,  Diplaspis  Acadica  Matthew  (1888),  are  found  at  West- 
field,  in  southern  New  Brunswick,  in  Silurian  shales  that  underlie  Niagara 
beds,  and  are  supposed  to  be  of  the  Clinton  group.  The  same  beds  contain 
"  myriads  "  of  the  Ceratiocaris  pusilla  of  Matthew., 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


547 


A  few  of  the  many  Corals  in  the  Niagara  group  are  represented  in 
the  following  figures,  761-766.  Fig.  761  is  one  of  the  Cyathophylloids  or 
cup  Corals ;  762,  a  Favosites,  a  columnar,  tabulate  Coral,  so  named  from  favus, 
a  honeycomb,  in  allusion  to  its  columnar  structure ;  763,  a  chain  Coral,  or 


761 


COBALS. — Fig.  761,  Chonophyllum  Niagarense  ;  762,  a,  Favosites  Niagarensis;  763,  Halysites  catenulatus;  764, 
765,  Heliolites  spiniporus  ;  766,  Stromatopora  concentrica.     Hall. 

species  of  Halysites,  mostly  imbedded  in  the  limestones ;  766,  a  Stromatopora, 
a  calcareous  Hydroid,  the  lines  showing  the  edges  of  the  very  thin,  barely 
distinguishable  layers. 

Figs.  767-770  are  the  forms  of  some  of  the  common  Crinoids  and  Cystoids. 
In  Fig.  767  the  arms  clustered  about  the  mouth  of  the  Crinoid  are  perfect. 
Fig.  768  has  the  box-like  body  of  a  Cystoid,  to  which  group  it  is  related.  It 


767-770. 


CBINOIDS.  —  Fig.  767,  Ichthyocrinus  tevis ;  768,  Caryocrinus  or natus  ;  769,  a,  6,  c,  Stephanocrinus  angulatus ; 
770,  Troostocrinus  subcylindricus.     Hall. 

had  slender  arms,  three  to  four  inches  long,  fixed  to  the  top  of  the  box, 
which  were  very  fragile  and  are  seldom  preserved.  The  stem  is  sometimes 
found  six  to  eight  inches  long.  The  genus  Stephanocrinus,  Fig.  769,  includes 
Crinoids  with  short  delicate  arms.  Among  Cystoids,  Callocystites  Jewetti, 
Fig.  444,  page  429,  is  very  common. 

Besides  the  above  forms,  the  Niagara  group  has  afforded  the  first  of  the 


548 


HISTORICAL   GEOLOGY. 


Blastoids,  or  Bud-crinoids,  which,  like  the  typical  Cystoids,  have  no  free 
arms,  and  usually  are  pentagonal  in  form.  A  species  from  the  Niagara  lime- 
stone of  Ohio  is  represented,  without  its  stem,  in  Fig.  770. 


BBACHIOPODS.  — Fig.  771,  Leptsena  rhomboidalis ;  772,  Plectambonites  transversalis ;  773,  a,  Atrypa  nodostriata ; 
774,  Meristina  (Whitfieldella)  nitida;  775,  Anastrophia  interplicata;  776,  a,  Rhynchotreta  cuneata;  777,  a,  6, 
Atrypina  disparilis ;  778,  o,  Orthis  biloba ;  779,  a,  Spirifer  Niagarensis  ;  780,  a,  Sp.  sulcatus.  Hall ;  except 
778,  Meek. 

Some  of  the  characteristic  Brachiopods  of  the  Niagara  group  are  repre- 
sented, natural  in  size,  in  Figs.  771  to  780  —  all  very  abundant  species. 

781-784. 


LAMELLIBRANCHS  AND  GASTROPODS.  —  Fig.  781,  Megalomus  Canadensis ;  782,  Avicula  emacerata ;  788,  Plfttjr- 
stoma  Niagarense ;  784,  a,  Platyceras  angulatum. 

Leptcena  rhomboidalis,  Fig.  771,  is  one  of  the  long-lived  species  —  as 
it  began  in  the  Trenton  period  and  continued  on,  with  little  change, 
through  the  Devonian. 


PALEOZOIC   TIME  —  UPPER    SILURIAN. 


549 


Lamellibranchs  are  not  numerous,  —  a  common  fact  with  limestones. 
One  of  them  from  the  Coralline  limestone,  and  also  from  Guelph  in  Ontario, 
is  shown  in  Fig.  781 ;  another  more  common  form,  an  Avicula,  in  Fig.  782. 
Figs.  783,  784  are  of  two  Gastropods,  the  latter  also  a  Clinton  group  species. 
A  Pleurotomaria  (P.  solarioides),  from  the  Guelph  limestone,  has  a  diameter 
of  four  inches.  There  were  also  Conularice  of  unusual  size.  Cephalopods 
include  species  of  Orthoceras,  Actinoceras,  Discosorus,  Huronia,  Gomphoceras, 
Trochoceras. 

The  following  figures,  785-789,  are  the  forms  of  some  of  the  Niagara 
Trilobites,  all  reduced  one  half  or  more.  The  Lichas  Boltoni  (Fig.  786)  has 
sometimes  a  length  of  seven  inches,  and  the  Homalonotus  (Fig.  787),  remark- 
able for  its  small  eyes,  even  a  greater  length.  The  Catymeue  Niagarensis  is 
very  similar  to  the  G.  callicephala  of  the  Trenton  period  (Fig.  690). 


785-789. 


785 


TBILOBITKS.—  Fig.  785,  Dalmanites  limulurus  (x  J) ;  786,  Lichas  Boltoni  (x  J)  ;  787,  Homalonotus  delphino- 
cephalus  (x  |)  ;  788,  Illaenus  loxus  (x  |).  CRUSTACEAN.  —789,  Beyrichia  symmetrica;  789  a,  same,  natural 
size.  Hall. 

Ceratiocarids,  among  Crustaceans,  occur  of  large  size.  The  telson,  or 
tail-spine,  of  one  from  western  New  York,  Ceratiocaris  Deweyi,  is  over  six 
inches  long,  indicating  a  length  for  the  Ceratiocaris  of  nearly  two  feet,  or  as 
great  as  that  of  C.  Angelini  (Fig.  729). 

Characteristic  Species. 

1.  Medina  Epoch. 

Fig.  744,  Arthrophycus  Harlani  H.  (1853)  =  Harlania  Halli  Gcepp.  (1852)  =  Fucoides 
Harlani  Con.  (1838).  Fig.  739,  Lingula  cuneata  Con. ;  Atrypa  (  Whitfleldella)  oblata  H. ; 
740,  Modiolopsis  orthonota  Con. ;  741,  M.  primigenia  Con. ;  742,  Pleurotomaria  litorea  H. ; 
P.  pervetusta  Con.;  743,  Bucania  trilobata  Con.,  different  views ;  Oncoceras  gibbosum  H. ; 
Orthoceras  multiseptum  H. 

2.  Clinton  Epoch. 

PLANTS.  —  Buthotrephis  gracilis  H.,  B.  ramosa  H.  A  Lycopod  (or  Fern)  has  been 
reported  from  Ohio  by  E.  W.  Claypole  (1878).  It  is  of  doubtful  nature. 


550  HISTORICAL   GEOLOGY. 

ANIMALS.     1.  Hydrozoans. — Fig.  750,  Graptolithus  Clintonensis  H. 

2.  Actinozoans.  —  Figs.  746,  747,  Zaphrentis  bilateralis  H. ;  Favosites  favosus,  Favi- 
stella  favosidea  H.,  Palceocyclus  rotuloides  H.,  Gannapora  junciformis  H.,  Halysites 
escharoides  Lamk.,  H.  catenulatus,  species  of  Cyathophyllum,  Streptelasma,  Aulopora, 
Diphyphyllum. 

3.-  Echinoderms.  —  Caryocrinus,  but  rare. 

4.  Molluscoids.  —  (a)  Bryozoans.  —  Fig.  751,  Fenestella  prisca  Lonsdale  ;  PtUodictya, 
Stictopora,  many  species. 

(6)  Brachiopods.  —  Species  of  Lingula,  Orthis,  Plectambonites,  JRhynchonella,  Spiri- 
fer,  Chonetes,  and  Pentamerus ;  Fig.  752,  Pentamerus  oblongus  Sow.  ;  some  specimens 
are  twice  the  size  of  the  figure  ;  the  interior  of  the  shell  is  shown  in  Figs.  753,  753  a ; 
Figs.  754,  a,  Atrypa  reticularis  Linn. ;  Figs.  755,  a,  Hyattella  congesta  Con.  (  =  Cama- 
rella  congesta) ;  Fig.  756,  Chonetes  cornutus. 

5.  Mollusks.  —  (a)  Lamellibranchs.  — Fig.  757,  Avicula  rhomboidea  H. ;  A.  emacerata 
Con.,  Tellinomya  machceriformis  H.,  abundant. 

(•&)  Gastropods.  —  Fig.  758,  Cyclonema  cancellation  H. ;  Bucania  trilobata  of  the 
Medina  also  occurs  here,  besides  other  Gastropods. 

6.  Crustaceans.  —  Homalonotus  delphinocephalus,  Calymene  Clintoni  Van. ,  C.  Niaga- 
rensis, Ceraurus  Niagarensis  H.,  Phacops  trisulcata  H. 

(a)  Ostracoids,  or  Bivalve  Crustaceans.  —  Fig.  789,  Beyrichia  symmetrica  H.,  showing 
one  of  the  valves;  789  a,  same,  natural  size;  B.  spinosa  H.,  Lockport.  (b)  Ceratio- 
carids.  —  Ceratiocaris  Deweyi  H.,  specimens  of  the  caudal  spine,  formerly  supposed  to 
belong  to  a  Fish,  and  named  Onchus  Deweyi.  Onchus  Clintoni  of  Claypole  is  from  the 
Iron  Sandstone  stratum  of  Perry  County,  Pa.  (1884, 1885)  ;  that  it  belonged  to  a  Fish  is 
not  certain. 

7.  Eurypterids  (Limuloids).  — Eurypterus  prominens  H. 

Among  the  Clinton  species  are  the  following  from  the  Lower  Silurian  :  Orthis  (Platy- 
strophia)  biforata,  Leptcena  (Plectambonites)  sericea,  Bellerophon  bilobatus,  Calymene 
callicephala.  The  following  are  known  in  Europe :  Orthis  biforata,  Atrypa  reticularis, 
Coslospira  (Atrypa)  hemisphcerica  Munch.,  Spirifer  radiatus  Sow.,  Pentamerus  oblongus. 

3.   Niagara  Epoch. 

1.  Spongiozoans.  — Astrceospongia,  Astylospongia,  Palceomanon  of  Rcemer  in  Tennes- 
see, in  the  upper  part  of  the  Niagara  (or  Meniscus)  limestone  ;  Astrceospongia  meniscus  is 
the  most.abundant.     (Sil.  Faun.  W.  Tenn.,  1870.) 

2.  Hydrozoans. —  Dictyonema,  common;  Fig.  766,  Stromatopora  concentrica  Goldf. 

3.  Actinozoans.  — Fig.  7Ql,Chonophyllum  Niagarense  H. ;  Streptelasma  calyculus  H., 
Astrocerium  venustum  H.,  masses  often  2  or  3  feet  in  diameter  ;  Strombodes  gracilis  Bill.  ; 
762,  Favosites  Niagarensis  H.  ;  F.  Gothlandicus  Lamk.,  F.  venustus  H. ;  763,  Halysites 
catenulatus  Linn.,  H.  escharoides  Lamk.,  H.  agglomeratus  H. ;  764,  Heliolites  spiniporus 
H. ;  765,  an  enlarged  view,  showing  the  12-rayed  cells,  and  the  interval  of  a  cellular  char- 
acter separating  them,  both  of  which  are  distinguishing  characteristics  of  the  genus  Helio- 
lites;  H.  interstinctus    Linn.,   H.  pyriformis   Guettard,   Syringopora   retiformis   Bill., 
S.  multicaulis  H.,  Aulopora precia  H.,  A.  repens. 

4.  Echinoderms.  —  Fig.  767,  Ichthyocrinus  Icevis  Con.,  Lockport,  sometimes  twice  as 
large  as  the  figure  ;  768,  Caryocrinus  ornatus  Say,  New  York,  Wisconsin,  and  Tennessee, 
named  from  Carya,  the  hickory-nut ;  769,  fitephanocrinus  angulatus  Con.,  Lockport ;  a, 
part  of  the  stem,  enlarged  ;  6,  joint ;  c,  base  of  the  body,  showing  the  3  pieces  of  which  it 
consists  ;  species  of  Melocrinus,  Eucalyptocrinus  decorus  Phillips,  New  York,  Kentucky, 
Tennessee;    Camarocrinus   Saffordi  H.,  Tennessee;   Lecanocrinus,  etc.     Also  Fig.  444 
(page  429),  the  Cystoid,  Callocystites  Jewetti  H. ;  Apiocystites  elegans  H.,  A.  Canadensis, 
and  A..  Huronensis  of  Billings,  from  Anticosti.     Troostocrinus  subcylindricus  H.  and 


PALEOZOIC   TIME  —  UPPER   SILURIAN.  551 

Wh.,  from  the  Niagara  beds  of  Ohio,  Fig.  770.     The  Star-fishes,  Palceaster  Niagarensis 
H.,  Glyptaster  occidentalis  H. 

5.  Molluscoids.  —  (a)    Bryozoans.  —  Many  species  of  delicate  Corals  of  the  genus 
Fenestella,  resembling  Fig.  751 ;  Trematopora,  and  other  genera.      (&)  Brachiopods.  — 
Fig.  771,  Leptcena  rhomboidalis  Wilck.  ;  772,  Plectambonites  transversalis  Dalman ;  Stro- 
phomena  depressa  Sow. ;   773,  Atrypa  nodostriata  H.,  the  Niagara  form  of  this  species ; 
773  a,  same,  side  view ;  A.  reticularis  Linn.  ;  A.  rugosa  H. ;  774,  Meristina  ( Whitfield- 
elld)  nitida  H.  ;  775,  Anastrophia  interplicata  H.  ;   776,  a,  Ehynchotreta  cuneata  Dalm. ; 
777,  a,  b,   Atrypina  disparilis  H.  ;   778,  Orthis  (Bilobites)  biloba  Linn.,  778  a,  same, 
enlarged  ;  0.  elegantula  Dalm.,  0.  hybrida  Sow.,  Nucleospira  pisiformis  H. ;  779,  Spirifer 
Niagarensis  Con.,  779  a,  same,  side  view  ;  780,  a,  Sp.  sulcatus  His. ;  Pentamerus  oblongus 
(Fig.  752),  a  Clinton  group  species,  abundant  in  the  Niagara  limestone  of  the  Mississippi 
basin  ;  Pentamerus  occidentalis  H.,  from  the  Guelph. 

6.  Mollusks.  —  (a)  Lamellibranchs.  —  Fig.  781,  Megalomus  Canadensis  H.,  from  the 
Guelph,  Canada  ;  782,  Avicula  emacerata  Con.  ;  Orthonota  curta  H. 

(6)  Gastropods.  —  Fig.  783,  Platystoma  Niagarense  H.  ;  784,  Platyceras  angulatum 
H. ;  Murchisonia  bivittata  H.,  M.  macrospira  H.,  Subulites  ventricosus  H.,  Pleurotomaria 
solarioides  H. 

(c)  Pteropods. —  Conularia  Niagarensis  H.,  C.  longa  H.,  Lockport. 

(d)  Cephalopods.  —  Orthoceras   annulatum    Sow.,  0.    rectum  Worthen,    Orthoceras 
(Kionoceras  Hyatt)  strix  Worthen ;  Phragmoceras  parvum  H.  and  Whitf .,  Huronia  Bigs- 
byi  Stokes,  H.  vertebralis  Stokes,  Gomphoceras  Wabashense  and  G.  angustum  Newell, 
Pentameroceras  mirum  Barrande,  Ascoceras  Newberryi  B.,  Hexameroceras  delphicolum 
Newell,  etc.,  Lituites  Marshi  Hall,  Trochoceras  costatum  H.,  T.  notum  H.,T.  Desplain- 
ense  McChesney. 

7.  Crustaceans.  —  Fig.  785,  Dalmanites  limulurus  Green  ;  786,  Lichas  Boltoni  Bigsby ; 
787,  Homalonotus  delphinocephalus  Green,  one  specimen  7  inches  long  and  5  broad  ;  788, 
Illcenus  loxus  H. ;  Calymene  Niagarensis  H. ,  near  Fig.  690  ;  Ceraurus  Niagarensis  H.  ; 
Proetus  Stokesi  Murch.,  at  Lockport. 

The  following  genera  and  species  of  fossils  have  been  identified  in  the  Niagara  beds 
of  Littleton,  N.H. :  Favosites  basalticus,  F.  Gothlandicus,  Syringopora,  Stromatopora, 
Halysites  near  catenulatus,  Zaphrentis,  Leptcena  rhomboidalis,  Stropheodonta,  Pentamerus 
Knightii,  Trematospira  multistriata  H.,  Pleurotomaria,  Dalmanites  limulurus  abundant. 

In  the  Anticosti  beds  there  are  Cephalopods  of  the  genera  Orthoceras,  Cyrtoceras, 
Oncoceras,  Ascoceras,  and  Glossoceras ;  and  Trilobites  of  the  genera  Asaphus,  Calymene, 
Illcenus,  Phacops,  Dalmanites,  Encrinurus,  Harpes,  Lichas,  etc.,  and  among  these  Asaphus 
megistos  and  Calymene  Blumenbachii. 

A  section  of  the  Anticosti  group,  or  that  of  Anticosti  Island,  on  the  north  side  of  the 
St.  Lawrence  Bay,  opposite  Gaspe,  is  particularly  described  by  Logan  in  the  volume  of 
the  Canadian  Survey  for  1863  (pages  298-310),  and  the  fossils  in  its  successive  parts  are 
enumerated  from  determinations  by  Billings,  and  also,  where  new,  described  by  the  latter. 

The  following  are  some  of  the  species  common  to  the  Niagara  and  Clinton  groups :  — 

Halysites  catenulatus  (Fig.  763).  Avicula  emacerata  (Fig.  782). 

Caryocrinus  ornatus  (Fig.  768).  Orthonota  curta. 

Eucalyptocrinus  decorus.  Modiolopsis  subalata. 

Lingula  lamellata.  Ceraurus  Niagarensis. 

Orthis  elegantula  (Fig.  723).  Homalonotus  delphinocephalus  (Fig.  787). 

Leptsena  rhomboidalis  (Fig.  771).  Calymene  tuberculosa. 

Pentamerus  oblongus  (Fig.  752).  Calymene  Niagarensis. 

Rbynchonella  neglecta.  Dalmanites  limulurus  (Fig.  785). 

Atrypa  reticularis  (Fig.  754).  Illsenus  loxus  (Fig.  788). 

Spirifer  radiatus. 


552  HISTORICAL    GEOLOGY. 

Foerste  reports  the  absence  of  several  Clinton  fossils  from  the  Clinton  beds  along  the 
borders  of  the  Cincinnati  geanticline  in  Ohio  and  Indiana  that  occur  in  New  York  (B.  S. 
JV.  H.,  1889). 

According  to  Salter,  a  number  of  species  of  the  Upper  Silurian,  and  probably  of  this 
part  of  it,  have  been  observed  in  Arctic  rocks  on  the  shores  of  Wellington  and  Barrow 
Straits  and  on  King  William's  Island,  lat.  72°  to  76°  ;  Halysites  catenulatus,  Orthis 
elegantula,  Favosites  Gothlandicus,  Leperditia  Baltica  Hisinger,  species  of  Calophyllum, 
Heliolites,  Cystiphyllum,  Cyathophyllum,  Syringopora,  with  Pentamerus  conchidium 
Dalm.,  Atrypa  reticularis,  etc.;  and,  at  the  southern  extremity  of  Hudson  Bay,  Penta- 
merus oblongus,  Atrypa  reticularis,  etc.  Trochoceras  boreale  Foord  is  from  Wellington 
Channel.  Between  79°  and  82°  5',  the  expedition  of  Captain  Nares  obtained,  accord- 
ing to  Etheridge,  Corals  of  the  genera  Halysites,  Favosites,  Heliolites,  Favistella,  Zaph- 
rentis,  Amplexus,  Cyathophyllum,  and  Arachnophyllum,  and  Trilobites  of  the  genera 
Bronteus,  Calymene,  Encrinurus,  and  Proetus,  with  Brachiopods  of  Pentamerus,  Ehyn- 
chonella,  Chonetes,  Atrypa,  Strophomena.  About  Lake  Winnipeg,  also,  Upper  Silurian 
fossils  have  been  found.  See  Am.  Jour.  Sc.,  II.,  xxi.  313,  xxvi.  119 ;  III.,  xvi.,  1878. 

The  beds  of  northern  Maine,  about  Square  Lake,  described  by  C.  H.  Hitchcock,  have 
afforded  both  Niagara  and  Lower  Helderberg  fossils,  and  many  of  them  are  made  new 
species  by  Billings. 

The  Niagara  beds  of  the  vicinity  of  Cobscook  and  Penobscot  bays,  Maine,  contain, 
besides  Niagara  fossils,  some  of  the  Clinton  group  ;  the  latter,  in  Penobscot  Bay,  are 
mostly  confined  to  the  lower  half,  but  many  Niagara  species  occur  with  them.  (Shaler, 
1886  ;  Dodge  and  Beecher,  1892.) 


2.  THE  ONONDAGA  PERIOD. 

ROCKS  — KINDS   AND   DISTRIBUTION. 

The  Onondaga  period  embraces  two  somewhat  unlike  formations ;  one, 
the  Salina  beds  of  shales  and  marlytes,  or  the  Salt  group,  the  source  of  the 
brines  of  central  New  York  and  of  rock  salt  in  the  western  half  of  the 
state,  as  well  as  in  Ontario  and  Ohio ;  the  other,  the  Water-lime  group,  in 
general  an  impure  limestone,  along  with  the  overlying  Tentaculite  limestone. 
Each  was  of  shallow  water  origin,  and  partly  marsh-made ;  but  the  former  was 
produced  under  conditions  suited  for  the  deposition  and  storing  of  salt  from 
the  sea  water.  This  classification  was  first  proposed  by  D.  Sharpe,  in  1847. 

The  following  sections  (Figs.  790,  791,  from  Hall),  taken  on  a  north-and- 
south  line  south  of  Lake  Ontario,  show  the  relations  of  the  Onondaga  beds 
(6,  a,  6)  to  those  above  and  below,  —  they  being  underlaid  in  one  section 
(Fig.  790)  by  the  Niagara  beds  (5  c),  Clinton  (5  6),  and  Medina  (5  a),  and 
overlaid  in  the  other  (Fig.  791)  by  rocks  of  the  Upper  Helderberg  (9), 
Hamilton  (10  a,  10  6,  10  c)  and  Portage  group  (11),  the  Lower  Helderberg 
being  there  absent. 

The  rocks  spread  eastward  to  the  Hudson  Kiver  valley,  the  Water-lime 
occurring  as  a  thin  stratum  even  east  of  the  river  in  the  base  of  Becrafts 
Mountain,  near  Hudson,  N.Y.,  and  also  in  Mount  Bob,  a  few  miles  farther 
north,  in  each  case  resting  on  the  upturned  Hudson  formation.  They 
increase  in  thickness  westward.  They  extend  beyond  New  York  over  much 
of  Ohio,  cross  Ontario  to  Lake  Huron  and  northwestward  to  Mackinac  in 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


553 


Michigan,  and  thin  out  in  Wisconsin.  They  also  cross  Pennsylvania  south- 
westward.  They  have  not  been  observed  in  Missouri,  Iowa,  or  elsewhere  in 
the  Mississippi  valley.  They  are  absent  from  the  Black  Hills  of  Dakota, 

790. 


5a 


10  c 
10  b 


06  y  10  a 

Sections  illustrating  the  relations  of  the  Onondaga  beds.    Hall. 

and  nothing  definite  is  known  of  their  occurrence  over  the  Rocky  Mountain 
region,  or  the  Great  Basin,  or  in  California,  or  any  part  of  the  Pacific  Coast 
region. 

The  group  is  100  to  200  feet  thick  south  of  Albany  in  the  Helderberg 
Mountains,  800  in  Onondaga  County,  central  New  York,  1500  at  Ithaca, 
1600  in  central  Pennsylvania,  600  in  northern  Ohio,  and  only  100  in  southern 
Ohio. 

The  two  formations,  the  Salina  and  Water-lime,  are  not  consecutive 
strata,  but  more  or  less  cotemporaneous,  the  Water-lime  being  thin  where 
the  Salina  beds  are  thickest. 

Salina  Group. 

The  rocks  of  the  Salina  group  are  mostly  reddish  shales  or  marlytes,  with 
little  limestone,  which  is  usually  dolomyte ;  or  alternations  of  shales  with  thick 
beds  of  limestone.  In  either  case,  gypsum  and  rock  salt  are  often  present. 

The  outcrop  of  the  formation  extends  as  a  narrow  belt  across  New  York 
State,  extending  from  the  Helderberg  Mountains  south  of  Albany,  westward, 
passing  just  north  of  Sharon  Springs,  Syracuse,  and  Batavia  to  the  Niagara 
River  above  the  Falls,  where  the  thickness  is  but  300  feet.  From  this  belt  it 
dips  southward  beneath  the  higher  beds  of  the  Upper  Silurian  and  Devonian, 
becoming  1000  feet  below  the  surface  in  25  miles  nearly  south  of  Batavia, 
and  1500  feet  in  33  miles.  At  Syracuse  the  thickness  of  the  formation  is 
about  600  feet ;  at  Ithaca,  30  miles  south  of  the  belt,  it  is  1230  feet.  In 
western  Ontario,  Canada,  on  Lake  Huron,  about  Goderich,  the  thickness  is 
over  1400  feet,  the  lower  600  feet  consisting  of  limestone,  shale,  and  salt, 
and  the  rest  of  dolomyte ;  and  to  the  south,  near  Cleveland,  Ohio,  there  are 
750  feet  of  shale,  limestone,  and  rock  salt  beneath  800  feet  of  dolomyte. 

Salt  springs  occur  in  many  parts  of  New  York,  west  of  Syracuse  and 
Tully.  Those  around  Onondaga  Lake  led,  first  in  1825,  to  the  sinking  of 
wells  70  feet  to  75  feet  deep  at  Salina,  for  the  manufacture  of  salt  by  evapo- 
ration. Rock  salt  appears  to  have  been  first  discovered  in  New  York,  in 
Bristol,  Ontario  County,  at  a  depth  of  1200  to  1300  feet ;  but  the  discovery 


554  HISTORICAL   GEOLOGY. 

that  attracted  attention  was  made  when  boring  for  gas  or  oil,  in  1878,  in 
Wyoming  County,  a  dozen  years  after  the  discovery  at  Goderich,  and  ten 
years  before  that  near  Cleveland,  Ohio. 

By  evidence  from  borings,  rock  salt  is  now  known  to  occur  in  New  York 
at  depths  of  800  to  3000  feet  or  more,  over  an  area  measuring  150  miles 
from  east  to  west,  and  60  to  65  miles  in  width  if  extending  only  to  the 
Pennsylvania  boundary.  The  northern  limit  of  the  area  is  near  Morrisville, 
where  12  feet  of  salt  were  found,  and  near  Leroy,  100  miles  west  of 
Syracuse,  where  a  bed  40  feet  thick  exists.  To  the  south,  in  Livingston 
and  Wyoming  counties,  beds  of  salt  occur  at  depths  of  1000  to  2500  feet, 
and  they  have  an  aggregate  thickness  of  50  to  100  feet,  some  beds  of  pure 
salt  being  40  to  80  feet  thick.  At  Ithaca,  the  several  beds  of  salt  have 
together  a  thickness  of  250  feet ;  they  alternate  with  shale  between  depths 
of  1900  feet  and  3130  feet.  At  Goderich,  six  beds  6  to  35  feet  thick  were 
passed  in  a  boring  1617  feet  deep ;  and  other  localities  occur  within  40  miles 
to  the  north,  east,  and  south.  Near  Cleveland  (at  Newburg)  there  are  four 
beds  5  to  50  feet  thick  in  a  range  of  beds  500  feet  thick,  between  2000  and 
2500  feet  below  the  surface.  The  evidence  shows  that  the  Goderich  basin 
is  independent  of  the  New  York,  as  pointed  out  in  1876  by  T.  S.  Hunt. 
How  it  is  related  to  the  Cleveland  basin  is  not  positively  known. 

The  strata  are  non-fossiliferous ;  but  as  they  include  beds  of  limestone, 
this  is  probably  owing  to  loss  of  shells  and  other  relics  by  trituration  through 
the  gentle  movements  of  the  water.  The  beds  abound  in  mud-cracks,  and 
other  evidences  that  they  were  made  as  mud-flats  or  bottoms  in  shallow 
water.  The  facts  are  believed  to  prove  that  the  region  through  which  the 
salt  beds  extend  was  an  area  of  great  salt  marshes  or  flats,  or  in  other  words 
"  salt-pans,"  over  which  sea  water,  admitted  at  intervals  from  the  interior 
continental  sea,  evaporated  and  deposited  salt.  The  fineness  of  the  material 
of  the  shales  is  such  as  would  be  produced  by  the  gentle  ripplings  of  such 
waters. 

The  gypsum  in  the  beds  sometimes  constitutes  layers,  but  oftener  parts 
of  layers,  or  imbedded  masses,  as  illustrated  in  the  following  figures  (from 
Hall);  but  the  most  of  the  gypsum  is  connected  with  the  overlying  Water- 
lime  beds.  The  lines  of  stratification  in  the  beds  sometimes  run  through 
the  gypsum,  as  in  Fig.  792;  and  in  other  cases  the  layers  of  the  shale  are 
bulged  up  around  the  nodular  masses  (Fig.  793).  In  all  such  cases,  the 
gypsum  was  formed  after  the  beds  were  deposited,  by  the  action  of  sulphuric 
acid  on  an  imbedded  mass  or  bed  of  limestone,  converting  Ca03C  into  gyp- 
sum (hydrous  lime  sulphate  =  Ca04S  4-  2  H20).  It  may  be  now  forming. 
Sulphur  springs,  emitting  sulphuretted  hydrogen,  are  common  in  New  York, 
and  especially  about  Salina  and  Syracuse.  Dr.  Beck  describes  several,  and 
mentions  one,  near  Manlius,  which  is  "  a  natural  sulphur  bath,  a  mile  and  a 
half  long,  half  a  mile  wide,  and  168  feet  deep,  —  a  fact  exhibiting  in  a  strik- 
ing manner  the  extent  and  power  of  the  agency  concerned  in  the  evolution 
of  the  gas"  and  showing,  it  may  be  added,  that  the  effects  on  the  rocks 


PALEOZOIC   TIME — UPPER   SILURIAN.  555 

below  must  be  on  as  large  a  scale.  These  sulphur  springs  often  produce 
sulphuric  acid,  by  the  oxidation  of  the  sulphuretted  hydrogen.  There  is  a 
noted  acid  spring  in  Byron,  Genesee  County,  N.Y.,  first  noticed  by  Amos 
Eaton  (Am.  Jour.  Sc.j  xv.,  1829),  whose  waters  Beck  showed  to  have  a 
specific  gravity  of  1-113.  The  laminae  which  pass  through  the  gypsum  unal- 
tered, as  in  Fig.  792,  are  those  which  consist  of  clay  instead  of  limestone. 

793. 


.ueas  ol'gypsuin  (g)  in  limestone  and  calcareous  siiaies.     Hall. 

The  gypsum  is  usually  of  an  earthy  variety,  of  dull  gray,  reddish  and  brown- 
ish, sometimes  black,  colors.  That  all  the  gypsum  of  the  formation  had 
this  source  is  reasonably  questioned.  It  may  have  been  in  part  a  deposit 
from  the  same  sea  waters  that  supplied  the  salt. 

Water-lime  Group. 

The  Water-lime  rock,  so-called  because  it  is  a  hydraulic  limestone,  is  an 
impure,  thin-bedded  magnesian  limestone  of  usually  a  drab  color.  It  some- 
times contains  a  little  petroleum.  It  owes  its  hydraulic  character  to  its  impur- 
ities, as  explained  on  page  79  (under  Rocks).  The  group  has,  in  general,  the 
distribution  above  given  for  the  Onondaga  series.  In  the  Helderberg  Moun- 
tains it  is  about  150  feet  thick,  and  nearly  the  same  in  the  central  part ;  but 
farther  north,  near  Oriskany  Falls  in  Oneida  County,  it  runs  out.  It  con- 
tains much  gypsum,  and  quarries  of  it  are  worked  near  Syracuse,  and  also  in 
Cayuga  and  Genesee  counties.  In  Northern  Ohio,  where  the  Onondaga  series 
has  a  thickness  of  600  feet,  it  contains  layers  of  shale ;  and  gypsum  is  abun- 
dant at  Gypsum,  10  miles  west  of  San  dusky.  Hydraulic  cement  is  made 
extensively  from  it  in  Ulster  County,  N.Y.,  at  Rosendale  near  Rondout, 
whence  the  oft-used  name  "Rosendale  cement,"  but  not  in  Ohio,  where  the 
limestone  is  not  suited  for  it.  The  presence  of  chert  is  one  cause  of  the 
unfitness  of  the  beds  for  the  purpose. 

In  the  New  York  report  by  Vanuxem,  the  salt  group  between  Oneida  Creek  and 
Cayuga  Lake  is  stated  to  consist  of  (1)  red  shales  with  green  spots,  1'  to  500'  thick; 
(2)  the  Lower  Gypseous  shales,  light  green  and  drab,  alternating  with  No.  1  near  the  plane 
of  junction ;  (3)  beds  containing  two  ranges  of  gypsum  in  masses,  and  often  containing  hop- 
per-shaped cavities  due  to  crystallized  salt,  the  Vermicular  limerock  of  Eaton  ;  and  (4)  im- 
pure limestone  containing  "Epsomites,"  or  vertically  grooved  surfaces  formerly  supposed 
to  have  been  made  by  the  crystallizing  of  Epsom  salts  (the  Stylolites,  mentioned  above). 

In  middle  Pennsylvania  there  are  700'  of  red  shales,  overlaid  by  700'  of  variegated 
shale  and  200'  of  gray  shale  (Claypole).  The  thickness  of  the  formations  overlying  the 
Salina  near  the  New  York  and  Pennsylvania  boundary  is  so  great  that  no  borings  have 
yet  penetrated  to  them.  On  the  salt  and  gypsum  industries  of  New  York,  see  the  Report 
of  F.  J.  H.  Merrill,  Bull.  N.  Y.  State  Mus.,  iii.,  1893,  which  contains  maps  showing  the 
distribution. 


556 


HISTORICAL   GEOLOGY. 


A  dike  of  a  chrysolitic  eruptive  rock,  altered  to  serpentine,  intersects  the  Salina 
group  at  Syracuse  (though  now  concealed  from  view),  which  was  first  described  by 
Vanuxem  in  1839,  and  by  Beck  in  1842,  and  has  recently  been  studied  and  explained  by 
G.  H.  Williams  (Am.  Jour.  Sc.,  1887). 


794-797. 


LIFE. 

The  fossils  that  have  been  supposed  to  occur  in  the  lower  beds  of  the 
Salina  group  in  New  York  are  referred  to  the  Niagara  group,  and  those  at 
the  top  are  Water-lime  species.  Eegarding  the  Water-lime  beds  of  Ohio  as 
synchronous  with  the  Salina  and  Water-lime  of  New  York,  the  fossils  of 
the  Water-lime  stand  for  those  of  the  Onondaga  period.  But  they  are  few 
in  number,  the  limestone  having  originated,  as  its  fine  texture  and  impurity 

show,  in  shallow  waters,  under  their  gentle 
triturating  action,  and  differing  in  origin  from 
the  Salina  beds  in  having  had  more  open 
connection  with  the  Interior  Continental  Sea. 
Unquestioned  remains  of  Fishes  are  among 
the  fossils,  and  also  the  first  of  American 
terrestrial  species,  a  Scorpion. 

Some  of  the  characteristic  fossils  of  the 
Water-lime  are  represented  in  the  annexed 
figures.  Fig.  794  is  the  more  common  species 
of  Tentaculites  of  the  Tentaculite  limestone, 
and  795  is  the  same  enlarged.  It  is  regarded 

Figs.  794,  795,  Tentaculites  gyracanthus ;  O.-L       5,1^11    ~f   Q    CTY,QH    -pf0™™/l        TTSo-     7Q« 

796,  Leperditia  alta;  797,  Eurypterus      RS    th6    Sne11    O±   a   Smali    ^terOpO<l.       Fig.    796 

remipes,  the  three  anterior  legs  of  the     is  an  Ostracoid  Crustacean  (Leperditia  alta); 

right  side  mutilated,  a  young  individ-      ft  j  ,  common   in  the 

ual.    Meek. 

Tentaculite  limestone  and 

Water-lime.  Fig.  797  represents  a  young  Eurypterid 
(Eurypterus  remipes),  a  common  species  in  the  Water- 
lime,  related  to  the  species  of  the  Trenton  period, 
mentioned  on  page  513,  but  of  different  genus.  Some 
specimens  are  a  foot  in  length.  E.  giganteus,  a  species 
from  near  Buffalo,  described  by  J.  Pohlman,  was  nearly 
six  inches  broad  and  probably  20  inches  long.  The  under 
surface  of  E.  remipes  restored  is  shown  in  Fig.  798 ;  and 
on  it  the  segments  of  the  thorax  and  abdomen  are  num- 
bered. Anteriorly,  the  members  of  the  cephalic  portion 
are  five  in  number  of  pairs,  and  they  serve  both  as  feet 
and  jaws,  as  in  the  modern  Limulus.  There  are  no  anten- 
nae corresponding  to  the  chelate  or  pincer-like  antennae  Restoration  of  Eurypterus 

£     T  •        j  -r»    i  •     1     j_i         i  1  •  i  •  remipes,  ventral  view. 

of   Limulus.     Behind    the    legs,    an    apron-like    pair   of         jjf,  mouth.    Hail, 
limbs,  with  a  narrow   prolongation   at  the   center,  per- 
tains to  the  first  thoracic  segment,  which  has  the  position  of  a  similar  pair 
in  Limulus. 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


557 


Other  genera  of  Eurypterids  have  their  species  in  the  Water-lime.     One 
from  Kokomo,  Indiana,  Carcinosoma  ingens  of  Claypole  (1894),  had  a  length 
of  24  inches.     In  Pterygotus,  which  is  one  of  them, 
there  are  chelate  antennae  at  the  front  margin,  and  799. 

the  caudal  segment  is  broad.  In  P.  acuticaudatus 
of  Pohlman,  from  near  Buffalo,  the  telson  alone  is 
6i  inches  long. 

Crustaceans  of  the  genus  Ceratiocaris  occur  in 
the  same  beds. 

Arachnids  represented  by  Scorpions.  —  The 
American  Scorpion  of  the  Water-lime  is  from 
beds  at  Waterville,  N.Y.  It  is  represented  in 
Tig.  799,  from  a  paper  by  R.  P.  Whitfield  (1885). 

Vertebrates. — Remains  of  Placoderm  Fishes, 
related  to  the  Pteraspids  (page  566),  occur  in  the 
upper  portion  of  the  Onondaga  beds  of  middle 
Pennsylvania,  and  have  been  described  by  E.  W. 
Claypole  (1884,  1892).  Fig.  800  represents  two 
imperfect  plates,  which  are  supposed  to  be  parts 
of  dorsal  and  ventral  shields ;  Figs.  801,  802,  side 
views  of  a  dorsal  plate,  showing  also  the  lateral 
plate ;  Fig.  803,  a  pectoral  fin ;  and  804,  a  restora- 
tion, giving  the  supposed  form  of  the  Fish. 


Proscorpius  Osborni  (x  2). 
Whitfield. 


The  few  fossils  of  the  Onondaga  beds,  which  occur  in 
the  non-saliferous  portion,  exclusive  of  the  Tentaculite 
limestone,  include  the  following :  — 

Orbiculoidea  Vanuxemi  H.,  Meristella  sulcata  Van.,  Leperditia  alta  Con.,  species  of 


800-804. 


PLACODEBM.  — Palaeaspis  Americana:  Fig.  800,  two  plates,  supposed  to  be  part  of  ventral  and  dorsal,  in  po- 
sition ;  801,  802,  side  view  of  dorsal  plate,  with  the  lateral  plate ;  803,  pectoral  fin  ;  804,  restoration,  giving 
probable  form  (all  x  |).  Claypole. 


Eurypterus,  Pterygotus,  Eusarcus,  Dolichopterus,  Ceratiocaris  (4  sp.),  Tentaculites  gyra- 


558  HISTORICAL   GEOLOGY. 

canthus  (Claypole).    The  telson  in  Fig.  797  is  half  too  short ;  it  was  partly  buried  in  the 
rock  when  drawn,  and  has  been  recently  uncovered  by  C.  E.  Beecher. 

The  Tentaculite  limestone  has  afforded  Camarocrinus  stellatus  H.  (a  form  found  also 
in  Bohemia),  Stropheodonta  varistriata  Con.,  Spirifer  Vanuxemi,  Tellinomya  nuclei- 
formis  H.,  Modiolopsis  (?)  dubia  H.,  Avicula  obscura  H.,  Holopea  subconica  H., 
H.  antiqua  H.,  H.  elongata  H.,  Murchisonia  extenuata  H.,  M.  minuta  H.,  Oncoceras 
ovoides  H.,  Cyrtoceras  subrectum  H.,  Spirorbis  laxus  H.,  Beyrichia  trisulcata  H. 

3.  THE  LOWER  HELDERBERG  PERIOD. 
ROCKS  — KINDS  AND  DISTRIBUTION. 

The  preceding  Onondaga  formation  has  been  described  as  extending  far 
eastward,  as  well  as  westward,  but  as  having  its  greatest  thickness  in  central 
New  York,  central  Pennsylvania,  and  Ohio.  The  Helderberg  beds  not  only 
extend  far  eastward,  but,  in  contrast  with  the  preceding,  have  their  greatest 
thickness  to  the  eastward,  and  thin  out  in  western  New  York.  They  are 
doubtfully  recognized  in  Ohio,  20  feet  being  the  greatest  thickness  reported. 
The  representative  rocks  over  the  Central  Interior  Sea  have  not  been 
made  out. 

East  of  Hudson  Eiver  the  beds  constitute  the  low,  isolated  elevation 
called  Becrafts  Mountain,  near  Hudson,  excepting  its  basal  layer  (the 
Water-lime)  and  the  upper  stratum,  which  is  of  the  Oriskany  sandstone 
with  the  Cauda-galli  grit ;  also  the  smaller  and  similar  Mount  Bob,  not  far 
distant  to  the  north.  Each  of  these  hills  is  all  that  is  left  of  a  great  for- 
mation after  ages  of  denudation.  Logan  was  probably  right  in  his  conclusion 
that  it  once  extended  northward,  along  the  Hudson  Eiver  and  Lake  Champlain 
valleys,  to  Montreal ;  for  similar  beds  occur  on  the  island  of  St.  Helens  in 
the  St.  Lawrence,  opposite  Montreal,  resting  on  Utica  shale  of  the  Lower 
Silurian.  Hence  the  waters  of  the  Eastern  Interior  Sea  during  this  Lower 
Helderberg  era  had  resumed  their  deep  connection  with  the  waters  of  the 
St.  Lawrence  region  about  Montreal. 

The  beds  are  300  to  400  feet  thick  in  eastern  New  York,  350  feet  in 
central  Pennsylvania  (Perry  County),  and  600  in  eastern  (in  Monroe  County), 
and  in  New  Jersey.  They  occur  also  in  the  Appalachians  in  Virginia,  but  not 
in  eastern  Tennessee.  They  are  20  to  100  feet  thick  in  western  Tennessee, 
and  175  feet  thick  in  Missouri,  but  are  not  distinct  in  Illinois  or  Wisconsin. 
In  other  words,  the  beds  are  either  thin  or  wanting  over  the  Central  Interior 
region. 

The  St.  Lawrence  tidal  waters  of  this  period  must  have  extended  westward 
to  the  borders  of  Vermont  and  Montreal  and  southward  along  the  Connecticut 
valley.  In  Canada,  in  the  line  of  the  Connecticut  valley,  Lower  Helderberg 
fossils  occur  in  Dudswell  and  near  Lakes  Massawipi  and  Aylmer.  They  are 
also  found  in  northern  New  Brunswick,  northern  Maine,  near  Square  Lake, 
and  along  the  Gaspe-Worcester  trough.  They  also  occur  in  southern  New 
Brunswick  and  near  the  coast  in  Pembroke,  Me.,  with  many  fossils,  and  in 
northern  Nova  Scotia,  within  the  limits  of  the  Acadian  trough. 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


559 


805-806. 


The  Lower  Pentamerus  limestone,  Delthyris  Shaly  limestone,  Encrinal 
limestone,  and  Upper  Pentamerus  occur  in  eastern  New  York.  The  upper 
two  of  these  subdivisions  are  quite  distinct  in  eastern  New  York,  though 
not  separable  in  the  center  of  the  State.  They  thin  out  in  Cayuga  County. 

In  the  Arctic  regions,  Kennedy  Channel,  latitude  79°-80°,  fossils  were 
obtained  by  Dr.  Hayes,  which,  according  to  Meek  (J.  Sc.,  1865),  closely  re- 
semble those  of  the  Shaly  limestone  of  the  Lower  Helderberg  of  New  York. 

LOWER  HELDERBERG.  —  The  Lower  Pentamerus  limestone,  overlying  the  Water-lime, 
to  the  eastward,  is  compact,  and  mostly  in  thick  layers  and  about  50'  thick.  The  Catskill 
or  Delthyris  Shaly  limestone  (No.  3)  consists  of  shale  and  impure  thin-bedded  limestone. 
An  upper  part  of  the  formation  was  called  the  Scutella  limestone  by  Vanuxem  in  his 
Annual  New  York  Report,  the  Scutella  referred  to  being  the  discoidal  basal  plate  of  an 
Encrinite.  A  bed  of  limestone  corresponding  to  these  two  divisions,  but  without  the  sub- 
division, has  a  thickness  of  65'  on  Cayuga  Lake. 

Part  of  the  so-called  Upper  Pentamerus  of  eastern  New  York,  in  the  Hudson  valley, 
according  to  recent  observations  of  C.  E.  Beecher,  fails  of  the  characteristic  fossils  of  the 
group,  and  is  referred  by  him  to  the  lower  Oriskany  ;  it  includes  the  impure  limestones 
above  the  Encrinal  limestone  at  Becrafts  Mountain,  near  Catskill,  and  southward.  The 
Upper  Pentamerus  is  distinct  at  Schoharie  and  westward  nearly  to  the  center  of  the  state, 
where  all  the  subdivisions  of  the  period  merge  together. 

Becrafts  Mountain,  two  miles  east  of  the  Hudson,  near  Hudson,  consists  below  (1)  of 
a  thin  bed  of  the  Tentaculite  limestone  of  the  Water-lime ;  (2)  Lower  Pentamerus,  40' 
to  50' ;  (3)  Shaly  limestone,  50'  to  60' ;  (4)  Encrinal  limestone,  40' 
to  50'.     Over  these  occur  the  Oriskany  sandstone  and  the  Cauda- 
galli  grit. 

In  west  Tennessee,  light-blue  limestones  of  this  period,  abound- 
ing in  fossils,  occur  in  Hardin,  Henry,  Denton,  Decatur,  and  Stewart 
counties.  The  maximum  thickness  is  about  100'.  In  southern  Illi- 
nois there  are  beds  of  siliceous  limestone  underlying  the  Clear  Creek 
limestone,  the  lower  part  of  which  Worthen  refers  to  this  period. 
They  rest  directly  upon  limestones  of  the  Cincinnati  or  Hudson 
age  (the  Cape  Girardeau  limestone  of  the  Missouri  Report),  no 
Niagara  limestone  intervening  (Worthen). 

In  the  Appalachian  region  in  Pennsylvania,  the  Lower  Helder- 
berg, consisting  also  of  impure  limestones,  has  a  thickness  of  100' 
or  more  in  the  middle  belt,  and  200'  to  250'  in  the  southeastern, 
which  thickness  is  maintained  along  the  Appalachian  chain 
(Rogers). 

In  the  Eastern  Border  region,  at  Pembroke,  Me.,  slates  and 
hard  sandstones  occur  with  many  fossils.  In  northern  Maine  the 
rock  is  limestone  ;  and  to  the  north  they  have  great  thickness, 
about  Lake  Temiscouata,  and  include  both  Niagara  and  Lower 
Helderberg  (L.  W.  Bailey).  The  formation  extends  northeastward 
to  Cape  Gaspe,  where  there  are  2000'  of  limestones,  the  larger  part 
referred  to  the  Lower  Helderberg  by  Logan,  with  the  upper  beds 
probably  Oriskany.  They  also  stretch  southwestward  toward  New 
Hampshire,  in  the  line  of  the  Gaspe- Worcester  trough. 

At  Arisaig,  in  northern  Nova  Scotia,  the  Lower  Helderberg 

beds  have  a  thickness  of  1040',  and  overlie  nearly  1293'  of  Niagara,  500'  of  Clinton, 
and  180'  of  Medina  beds  (H.  Fletcher,  in  an  extended  report  on  Nova  Scotia,  in  Hep. 
Can.,  1886). 


MI;, 


CYSTIDEANS.  —  Fig.  805, 
Apiocystites  Gebhardi, 
from  Hall;  806,  Ano- 
malocystites  cornutus, 
from  Meek. 


560 


HISTORICAL   GEOLOGY. 


LIFE. 

Plants  supposed  to  be  related  to  the  Equiseta  occur  in  the  Lower  Hel- 
derberg  sandstone  of  Michigan;  the  species  is  Annularia  Romingeri  of 
Lesquereux.  Another  species  from  the  same  region  is  the  Psilophyton  cor- 
nutum  Lesq. 

The  beds  abound  in  animal  fossils,  the  number  of  species  even  exceeding 
those  of  the  Niagara  group.  Species  of  the  JReceptaculites  group  occur  of 
large  size.  Crinoids  were  rather  numerous,  and  some  of  them,  like  Melo- 
crinus  nobilissimus,  were  remarkable  for  their  size  and  beauty.  Two  Cystoids 
of  the  period  are  shown  in  Figs.  805,  806 ;  the  stems  of  each  were  fitted  for 


807-815. 


80S  a 


SOS 


BBAOHIOPODS.  —  Fig.  807,  Strophonella  radiate ;  808,  a,  Khyncbonella  ventricosa ;  809,  a,  Pentemerus'galeatus ; 
810,  a,  P.  pseudo-galeatus  ;  811,  Eatonia  singularis  ;  812,  Meristella  sulcata;  813/Orthis  varica;  814,Spirifer 
macropleurus  ;  815,  Meristella  Isevis.  807,  808,  Hall ;  the  others,  Meek. 

anchoring  in  the  mud  of  the  sea  bottom.  The  last  of  reported  Graptolites 
occurs  in  the  rocks.  Polyp-corals  were  not  largely  represented;  Favosites 
Helderbergice  appears  to  have  been  the  most  common  kind.  Hydroid  Corals 
and  Bryozoans  were  numerous.  Tentaculites  were  common,  and  one  kind, 
T.  elongatus,  from  the  Shaly  limestone,  was  three  inches  in  length. 

Some  of  the  common  Brachiopods  are  represented  in  Figs.  807  to  815. 
Among  them  Figs.  809,  809  a,  are  of  Pentamerus  galeatus,  of  the  Lower 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


561 


816. 


Pentamerus  limestone,  and  810,  810  a,  P.  pseudo-galeatus,  of  the  Upper  Pen- 
tamerus ;  Fig.  814  is  of  Spirifer  macropleurus,  characteristic  of  the  Shaly 
limestone.  Species  of  Spirifer  and  Orthis,  and  Gastropods  of  the  genus 
Platyceras  were  numerous. 

The  Pentamerus  (Anastrophia)  Verneuili,  Fig.  816,  is  a  common  species 
in  the  Shaly  limestone  ;  it  occurs  abundantly  in  the 
Helderberg  Mountains,  and  also  in  Schoharie,  Car- 
lisle, and  other  places. 

Orthocerata  were  few  in  species,  of  the  genera 
Orthoceras,  Gomphoceras,  Cyrtoceras,  Oncoceras,  and 
others.  A  Gomphoceras,  G.  parculum,  of  Whit- 
eaves,  Fig.  817,  occurs  in  beds  of  probably  the  lower 
part  of  the  series  in  Manitoba.  Fig.  817  a  shows 
the  form  of  the  aperture. 

Among  Trilobites  occur  species  of  Dalmanites, 

Lichas,  Acidaspis,  Phacops  (Fig.  818),  Bronteus  (Fig.  819).  Dalmanites  pleu- 
ropteryx  Green,  D.  nasutus  Conrad,  D.  tridens  Hall,  having  the  front  of  the 
head-shield  at  the  center  prolonged  into  a  beak,  and  three-pointed ;  Lichas 
Bigsbyi  Hall,  L.  pustulosus  Hall,  ornate  with  tubercles  and  having  the  margin 
of  the  pygidium  deeply  dentate,  are  among  the  species. 


Pentamerus  (Anastrophia)  Ver- 
neuili.    Hall. 


817, 


819. 


CEPHALOPOD. —  Fig.  817,  Gomphoceras  parvulum  ;  817  a,  upper  view  showing  aperture.     TBiLdBiTES.  —  Fig. 
818,  Phacops  Logani ;  819,  Bronteus  pompilins.    817,  817  «,  Whiteaves ;  818,  Hall ;  819,  Bfflings. 

An  upper  view  of  the  head  of  Acidaspis  tuberculata  is  shown  in  Fig.  820, 
a  section  of  a  segment  of  the  thorax  in  821,  and  the  pygidium  or  caudal 
extremity  in  822.  Fig.  824  is  a  dorsal  view  of  the  young  of  the  same  Tri- 
lobite,  when  but  a  twenty-fifth  of  an  inch  long,  as  described  by  C.  E.  Beecher. 
As  the  figure  represents,  the  larve  is  nearly  all  head ;  only  a  small  lower 
part  of  the  figure  corresponds  to  the  posterior  portion  of  the  body.  Fig.  825 
shows  the  larval  Acidaspis  in  profile. 

The  genus  Monticulipora  and  many  others  and  a  few  Polyp-corals  are  described  by 
Hall  in  Pal.  N.  F.,  vol.  vi. ;  Crinoids  and  Cystoids  in  Part  vi.,  vol.  iii. ;  also  Brachiopods, 
Gastropods,  Cephalopods,  and  Trilobites  in  the  same  ;  Pteropods  in  vol.  vii. 
DANA'S  MANUAL  —  36 


562 


HISTORICAL  GEOLOGY. 


CJiaracteristic  Species. 
Some  of  the  species  of  the  subdivisions  from  eastern  New  York  are  :  — 

1.  LOWER  PENTAMERUS.  —  Lepadocrinus  Gebhardi,  Rhynchonella  semiplicata,  Penta- 
merus  galeatus,  Meristella  Icevis  (also  in  the  Shaly),  Favosites  Helderbergice. 

2.  SHALY  LIMESTONE. — Hemipronites  radiatus,  H.  punctuliferus,  Orthis  oblata,  0. 
planoconvexa,   0.  varica,  Eatonia  singularis,   Spirifer  macropleurus,  Sp.  perlamellosus> 
Sp.  cyclopterus,  Platyceras  ventricosum,  Dalmanites  pleuropteryx. 

3.  UPPER    PENTAMERUS.  —  Pentamerus    pseudogaleatus,    Bhynchonella    ventricosa, 
E.  nobilis  H. 

820  820-82o. 


Acidaspis  tuberculata,  Fig.  820,  upper  view  of  head  of  an  adult  (1|) ;  821,  segment  of  thorax  (,l£) ;  822,  pygi- 
dium  of  adult  (x  §) ;  823,  pygidium  of  young  (x  3|)  ;  824,  dorsal  view  of  larva  (x  80) ;  825,  profile  view  of 
same  (x  30).  Beecher. 

Atrypa  recticularis  and  Leptcena  rhomboidalis  of  the  Niagara  are  supposed  to  be  the 
only  species  that  are  continued  into  the  Lower  Helderberg. 
Some  of  the  genera  are  as  follows  :  — 

1.  Spongiozoans.  —  Stromatopora,   very   common   in   the   Lower  Pentamerus,  con- 
stituting in  some  places  a  bed  3  or  4  feet  thick.    Also  Ischadites,  Hindia,  Heceptaculites 
infundib  u  I  iform  is. 

2.  Actinozoans.  —  Streptelasma,  Zaphrentis,  Michelinia  (begins),  Favosites  (of  which 
F.  Helderbergice  is  often  a  foot  across),  Aulopora. 

3.  Echinoderms.  —  Lepadocrinus,  Anomalocystites,  Sphcerocystites,  Melocrinus,  Cor- 
dylocrinus,  Edriocrinus,  Homocrinus,  Coronocrinus,  Protaster  (P.  Forbesii  H.). 

4.  Brachiopods. —  Orthis  (many  species),    Strophomena    (Leptcena  of   Hall,   1892), 
Stropheodonta,   Chonetes  (2),  Mhynchonella  (numerous  species),   Pentamerus,  Eatonia, 
Anastrophia,  Spirifer  (very  many,  some  with  dichotomizing  ribs,  a  feature  especially  of 
later  time),  Cyrtina,  Trematospira  (several  species),  Meristella,  Atrypa,  Eensselceria. 

5.  Mollusks.  —  Lamellibranchs.  —  Aviculopecten,  Mytilarca,  Megambonia,   Cypricar- 
dinia,  Conocardium. 

Gastropods.  —  Platyceras,  Platystoma,  Holopea,  Loxonema,  Murchisonia,  Pleuroto- 
maria,  Strophostylus,  Euomphalus,  Bucania. 

Cephalopods. —  Orthoceras  of  several  species,  Oncoceras  ovoides  H.,  Cyrtoceras. 
Pteropods.  —  Conularia,  Tentaculites,  and  Hyolithes. 

6.  Crustaceans.  —  Besides    those    mentioned,    Bronteus,    Homalonotus,    Cyphaspis, 
Proetus.     The  Ostracoid  genera,  Leperditia,  Beyrichia,  ^Echmina. 

The  Lower  Helderberg  beds,  near  Eastport,  southeastern  Maine,  include  Favosites 
cervicornis,  Leptcena  rhomboidalis,  Chonetes  Novascoticus,  ^Rhynchonella  Wilsoni,  Atrypa 
reticularis,  Orbicluoidea  tenuilamellata,  Spirifer  sulcatus,  Orthis  elegantula,  Avicula 
naviformis,  Calymene  Blumenbachii,  Homalonotus  Dawsoni,  Conulites  Jlexuosus,  Tenta- 
culites  distans,  Beyrichia  lata,  and  others  (W.  A.  Rogers). 


PALEOZOIC  TIME  —  UPPER   SILURIAN.  563 

For  a  list  of  163  Upper  Silurian  species  found  at  Arisaig,  Nova  Scotia,  see  H.  M.  Ami, 
Nova  Scotia  Inst.  Sc.,  1892.  In  this  paper  Ami  remarks  on  the  relations  of  the  fossils 
that  "they  are  much  closer  to  the  Ludlow  rocks  of  Kendal,  in  Westmoreland,  England, 
than  to  either  the  Upper  Silurian  species  of  Anticosti,  of  Ontario,  or  those  of  the  state  of 
New  York."  The  species  range  from  the  Medina  to  the  Lower  Helderberg. 

Hall  remarks  that  many  Niagara  species  have  their  nearly  related  or  representative 
species  in  the  Lower  Helderberg :  thus,  Orthis  elegantula  is  represented  by  0.  subcarinata 
and  0.  perelegans ;  0.  hybrida  by  0.  oblata  and  O.  discus ;  0.  punctostriata  by  O.  tubu- 
lostriata;  Spirifer  Niagarensis  by  8.  macropleurus ;  S.  sulcatus  by  8.  perlamellosus ; 
8-  crispus  by  8.  cyclopterus ;  Strophomena  (Orthothetes)  subplana  by  8.  (O.)  Wool- 
worthana.  So  also  Pentamerus  fornicatus  of  the  Clinton  is  represented  by  P.  galeatus. 

FOREIGN. 

The  rocks  of  the  Upper  Silurian  are  widely  distributed  over  the  globe, 
though  less  universal  than  those  of  the  Lower  Silurian.  They  occur  in  Great 
Britain,  Scandinavia,  Eussia,  Germany,  Bohemia,  and  Sardinia,  and  in  Asia, 
Africa,  and  Australia.  They  seem  on  a  geological  map  to  cover  but  small 
areas,  but  only  because  they  are  concealed  by  later  formations. 

The  rocks  in  Great  Britain  where  best  displayed  are  subdivided  as 
follows :  — 

1.  May  Hill  (Gloucestershire)  Sandstone,   or  Upper  Llandovery  group. — 

Sandstones,  with  some  arenaceous  limestone  ("Pentamerus  limestone"), 
which  terminate  above  in  the  Tarannon  shales.  —  American  Equivalent,  the 
Medina  and  Clinton  groups. 

2.  Wenlock  Group.  —  Consists  of  (1)  the  Woolhope  beds,  limestone  and 
shale;    (2)  Wenlock    shale;    (3)  Wenlock   or   Dudley    limestone.  —  Amer. 
Equiv.,  the  Niagara  shale  and  limestone. 

3.  Ludlow   Group.  —  Consists  of    (1)  the  Lower  Ludlow  rock;   (2)  the 
Aymestry  limestone ;  (3)  the  Upper  Ludlow ;  (4)  Tilestones.  —  Amer.  Equiv., 
the  Onondaga  and  Lower  Helderberg  groups. 

These  subdivisions  are  well  exhibited  in  Shropshire  or  western  England  and 
in  eastern  and  southern  Wales.  Between  the  Tilestones  and  the  Ludlow  are 
one  or  two  thin  bone-beds  consisting  of  remains  of  Fishes  and  Crustaceans. 
In  North  Wales,  and  in  Westmoreland,  Cumberland,  southern  Scotland,  and 
southwestern  Ireland,  the  beds  are  mostly  grits  and  shales,  and  are  much 
upturned,  with  the  subdivisions  not  distinct.  The  Wenlock  group  is  repre- 
sented by  the  Denbighshire  grit  in  North  Wales,  and  the  Coniston  grits  in 
Cumberland.  The  thickness  is  stated  to  be  from  3000  to  5000  feet. 

Upper  Silurian  beds  outcrop :  in  Russia  over  a  large  area  south  of  the  Gulf 
of  Finland ;  in  southern  Sweden ;  about  Christiania  and  some  points  to  the 
north  in  Norway;  in  the  Bohemian  basin  near  Prague,  where  Barrande's 
formation  E  corresponds  to  the  Niagara  and  Onondaga  periods,  and  his 
F,  G,  H.  approximately  to  the  Lower  Helderberg  and  Oriskany;  in  the 
Fichtelgebirge ;  and  the  upper  section  only  in  the  eastern  Hartz,  where  the 


564 


HISTORICAL   GEOLOGY. 


beds  are  the  Hercynian  of  Beyrich;  and  under  this  name  are  placed,  by 
Barrois,  beds  occurring  at  Erbray  in  the  Lower  Loire.  They  have  been 
identified  also  in  Sardinia,  India,  China,  Australia,  New  Zealand,  and  the 
Argentine  Republic. 

LIFE. 

The  Wenlock  and  Ludlow  beds  abound  in  fossils,  especially  the  former, 
which  represent  nearly  the  American  Niagara  group.  Evidence  of  British 
land  plants  occurs  in  the  Ludlow  beds ;  the  earliest  of  British  Fishes  — 
species  of  Pteraspis  and  Cephalaspis  —  in  the  Lower  Ludlow;  the  earliest 
of  Scorpions,  in  the  Upper  Ludlow  and  the  Upper  Silurian  of  Gothland, 
Sweden. 


826-831. 


831 


Fig.  826,  Omphyma  turbinata;  827,  Cystiphyllum  Siluriense;  828,  Crotalocrinus  rugosus;  829,  Pentamerus 
Knightii;  830,  Grammysia  cingulata;  831,  a,  Pterygotus  bilobus.  826,  827,  from  Edwards  and  Haime; 
828,  Murchison  ;  829,  Brown;  830,  Naumann  ;  831,  Salter. 

LAND  PLANTS.  —  The  Pachytheca  of  Hooker  is  supposed  to  be  the  spores 
or  sporangia  of  a  terrestrial  plant  (Q.  J.  G.  Soc.,  xxxviii.,  107,  1882).  The 
Denbighshire  grits  of  the  Wenlock  of  North  Wales  have  afforded  the  Nema- 
tophyton  of  Dawson,  having  loose  tubular  cells  within,  supposed  to  be  from  a 
tree  of  large  size,  but  now  admitted  to  be  a  Seaweed.  The  earliest  of  well- 
defined  ferns  has  been  described  by  Saporta  for  the  schists  of  Angers,  which 


PALEOZOIC   TIME  —  UPPER   SILURIAN. 


565 


are  referred  to  the  Middle  Silurian.  It  is  a  portion  of  the  frond  of  a 
Neuropteris. 

ANIMALS.  —  The  genera  of  Corals,  Crinoids,  Brachiopods,  Trilobites,  and 
of  other  classes  are  to  a  large  extent  the  same  as  in  America.  A  Crinoid  of 
an  unusual  form  is  represented  in  Fig.  828,  a  Crotalocrinus ;  Corals,  in  Figs. 
826,  827 ;  a  common  Pentamerus,  in  Fig.  829. 

Trilobites  are  common,  as  in  the  American  rocks.  Some  of  the  species 
are  represented  in  Figs.  832-841.  Figs.  832,  835,  and  838  are  of  species 
from  the  Wenlock ;  Figs.  833,  834,  836,  837,  839,  and  840  range  below,  and 
all  but  840  above,  the  Wenlock. 

Fig.  831,  from  Salter,  is  that  of  a  large  Limuloid,  of  the  genus  Pterygo- 
tus,  from  the  Wenlock  beds.  It  shows  well  the  chelate  termination  of  the 
antennae,  but  it  is  imperfect  in  wanting  the  four  pairs  of  slender  legs  which. 


832-841. 


Fig.  832,  Sphaerexochus  minis ;  833,  a,  Cheirurus  bimucronatus ;  834,  a,  Encrinurus  punctatus ;  835,  E.  variolaris ; 
836,  a,  Phacops  Downingii ;  83T,  Acidaspis  Brightii ;  838,  A..  Barrandii ;  839,  Cyphaspis  megalops  ;  840,  Proe- 
tus  latifrons  ;  841,  Hemiaspis  limuloides.  Figs.  832  to  840,  after  Murchison  ;  841,  after  Woodward. 

are  situated  between  it  and  the  large  posterior  pair  (see  page  623).  The 
jaws  in  the  figure,  one  of  which  is  separately  shown  in  Fig.  831  a,  are  the 
basal  portions  of  the  posterior  legs. 

Fig.  841  represents  the  Hemiaspis  limuloides  of  Woodward,  a  form  inter- 
mediate between  a  modern  Limulus  and  the  Eurypterids;  the  genus  has 
species  in  both  the  Wenlock  and  Ludlow  beds. 

A  Ceratiocaris  of  the  Ludlow  group  is  shown  in  Fig.  842.  Fig.  845,  a 
spine  (referred  to  a  genus  of  Sharks,  Onchus),  is  supposed  to  be  from  a 
Ceratiocaris. 

The  first  of  Amphipod  Crustaceans,  Necrogammarus  Salweyi,  is  reported 
from  the  Ludlow. 

A  Scorpion  has  been  found  in  the  Upper  Ludlow  beds  of  Lesmahago  in 
Lanarkshire,  Scotland,  and  in  beds  of  nearly  the  same  age  in  Gothland, 
Sweden ;  the  latter  is  named  the  Palceophonus  nuntius  by  Torell  and  Lind- 


566 


HISTORICAL  GEOLOGY. 


strom,  the  generic  name  meaning  the  ancient  murderer.     Both  specimens  have 
traces  of  spiracles,  showing  them  to  have  been  terrestrial  species. 


842. 


Ceratiocaris  papilio.    Salter. 

The  wing  of  an  insect,  Palceoblattina  Douvillei  of  Brongniart,  has  been 
found  in  the  sandstone  of  Jurques  in  northwestern  France,  and  for  the  pres- 
ent it  is  the  oldest  known  insect.  Its  relation  to  the  Cockroaches,  which  is 
thought  probable  by  Brongniart,  is  questioned  by  Scudder,  a  Neuropteroid 
character  being  thought  more  probable.  The  sandstone  is  of  the  age  of  the 
May  Hill  sandstone  of  England,  at  the  bottom  of  the  Upper  Silurian. 
Jaws  of  Annelids  of  several  species  have  been  described  by  Hinde  from  the 
Wenlock  and  Ludlow  groups. 

Fish-remains  occur  especially  in  the  bone-bed  below  the  Tilestones, 
and  also  in  the  Tilestones.  Fig.  843  represents  a  head-shield  of  Pteraspis 
Bariksii  Huxl.  &  S.  Fig.  844  is  the  head-shield  of  a  Cephalaspis  —  so  named 
from  the  Greek  for  a  shield-like  head.  A  complete  animal,  but  different  in 
species,  and  from  the  Devonian,  is  shown  in  Fig.  980 ;  and  Fig.  846  repre- 
sents probably  part  of  the  jaw-bone  of  a  Cephalaspis. 


—  Fig.  843,  Pteraspis  Banksii,  head-shield ;  844,  Cephalaspis  Murchisoni,  inside  of  head-shield  ;  845,  spine 
of  Onchus  tenuistriatus  =  Ceratiocaris  tenuistriata ;  846,  part  of  jawbone  of  Cephalaspis(?) ;  847,  shagreen 
pieces  (?),  Thelodus  parvidens.  Murchison. 

Fishes  of  the  Shark  tribe  are  supposed  to  be  indicated  by  spines,  teeth, 
and  portions  of  the  shagreen,  or  skin ;  but  all  are  doubtful.  A  number  of 
Upper  Silurian  Fishes  have  been  described  from  the  rocks  of  Russia  and 
Bohemia,  including  species  of  Coccosteus  and  Pterichthys,  and  the  fin-spines 
of  Sharks. 


PALEOZOIC   TIME  —  UPPER   SILURIAN.  567 

Characteristic  Species. 

1.  Upper  Llandovery.  —  Petraia,  species  of  Favosites,  Heliolites,  Syringopora,  Holy- 
sites,  Omphyma,  Palceocyclus,  Actinocrinus,  Palceechinus,    Tentaculites  ornatus,  Cornu- 
lites  serpularius,  Ccelospira  Scotica,  Ehynchonella  neglecta,  Meristella  angustifrons,  Stro- 
phomena  arenacea,  S.  compressa,  Pentamerus  oblongus,  P.  caudatus,  Stricklandinia  lens, 
S.  lyrata,  Orthis  lata,  O.  calligramma,  0.  elegantula,  Lyrodesma  cuneatum,  Pterinea  sub- 
Icevis,  Murchisonia  angulata,  M.  articulata,  Cyclonema  quadristriatum,  Euomphalus  ala- 
tus,  Haphistoma   lenticulare,  Holopella  obsoleta,    Conularia,    Calymene    Blumenbachii, 
Encrinurus  punctatus,   Illcenus    Thomsoni,  Proetus    Stokesi,    Phacops    Stokesi;     also 
Trinucleus  concentricus,  Lichas  laxatus,  Acidaspis,  etc. 

2.  Wenlock  Group.  —  Petraia  bina,  Cyathophyllum  truncatum  Linn.,  Favosites  Goth- 
landicus,  F.  fibrosus,  Halysites  catenulatus,  H.  interstinctus,  Syringopora  bifurcata,  Cysti- 
phyllum  Siluriense  (Fig.  827),  Stenopora  fibrosa,  Ptilodictya  scalpellum,  and  many  other 
Bryozoans  ;  Eucalyptocrinus  decorus,  Actinocrinus  simplex,  Crotalocrinus  rugosus  (Fig. 
828),  Marsupiocrinus  ccelatus,  Atrypa  reticularis,  Orthis  elegantula,  Ehynchonella  Wilsoni, 
It.  nucula,  Pentamerus  galeatus,  Leptcena  rhomboidalis,  Spirifer  elevatus,  S.  sulcatus, 
Nucleospira  pisum,  Obolus  Davidsoni,  Turrilepas*  Modiolopsis  complanata,  Conocardium 
cequicostatum,  Pterinea  retroflexa,  Grammysia  cingulata  (Fig.  830),  Orthoceras,  Lituites, 
Actinoceras,  Tentaculites  ornatus,  Acidaspis  coronata,  A.  hamata,  Calymene  tuberculosa, 
Homalonotus  delphinocephalus,  Lichas  Anglicus,  Phacops  caudata,  Encrinurus  variolaris. 

3.  Lower  Ludlow.  —  Palceasterina  primceva,  Protaster  Sedgwickii,  P.  hirudo,  Om- 
phyma turbinata,  Ehynchonella  Wilsoni,  JR.  navicula,  Cyrtia  exporrecta,  Spirifer  crispus, 
Strophonella  euglypha,  Atrypa  reticulans,  Lingula  lata,  Pentamerus  galeatus,  Orthonota 
ajftnis,  Loxonema  sinuosum,  Orthoceras  Ludense,  0,  annulatum,  Phragmoceras,  Lituites 
giganteus,  Calymene  Blumenbachii,  Phacops  caudata,  P.  longicaudata,  Proetus  latifrons, 
Acidaspis  Brightii,  Lichas  Anglicus,  Homalonotus  delphinocephalus,  Cyphaspis  megalops, 
Hemiaspis  sperata. 

4.  Aymestry  Limestone.  —  Tentaculites  ornatus,   Cyathophyllum  truncatum,  Penta- 
merus Knightii  (Fig.  829),  Atrypa  reticularis,  Shynchonella  Wilsoni,  E.  navicula,  E. 
Stricklandi,  Lingula  Lewisii,  L.  lata,  Strophonella  euglypha,  Meristella  ( Whitfieldella) 
didyma,   Chonetes  striatellus,  Bellerophon  dilatatus,   B.  trilobatus,   Lituites  giganteus, 
Orthoceras  tenuiannulatum,   Pterinea     Sowerbyi,    P.   hians,    Calymene   Blumenbachii, 
Homalonotus  delphinocephalus,  Phacops  caudata. 

5.  Upper  Ludlow. — Lingula  minima,  L.  lata,  Orbiculoidea  rugata,  Atrypa  reticularis, 
Ehynchonella  Wilsoni,  Orthis  elegantula  var.  orbicularis,  O.  lunata,  Stropheodonta  Jilosa, 
Strophonella  euglypha,  Chonetes  striatellus,  C.  latus,  Orthonota  angulifera,  Platyschisma 
helicites,  Holopella  obsoleta,  H.  gregaria,  H.  conica,  Cyclonema  corallii,  Murchisonia 
corallii,  Bellerophon  carinatus,  Orthoceras  bullatum,  Homalonotus  Knightii,  Encrinurus 
punctatus,    Phacops    Downingii,     Calymene    Blumenbachii,    Ceratiocaris,   Dictyocaris, 
Entomis,  Beyrichia,  Leperditia,  Eurypterus,   Pterygotus  bilobus  (Fig.   831),  Slimonia, 
Stylonurus. 

Fishes  from  the  Lower  Ludlow  include  only  Scaphaspis  (Pteraspis)  Ludensis ;  from 
the  Upper,  mostly  from  the  bone-bed,  Cephalaspis  ornata,  C.  Murchisoni,  Plectrodus 
mirabilis,  P.  pleiopristis,  Pteraspis  Banksii,  P.  truncata,  Scaphodus  Ludensis,  Thelodus 
parvidens,  Thysetes  verrucosus,  and  others.  There  are,  also,  in  the  same  rocks  Coprolites 
from  some  of  these  Fishes,  containing  fragments  of  the  shells  of  the  Mollusks  and  Cri- 
noids  on  which  they  fed.  Remains  of  Fishes  have  also  been  found  in  the  upper  part  of 
the  Upper  Silurian  of  Russia  and  Bohemia.  Ctenacanthus  Bohemicus  Barr,  abundant  in 
Stage  G. 

The  Hercynian  fossils  of  the  Hartz  and  Erbray  have  closer  analogy  with  those  of  the 
Lower  Helderberg  than  with  those  of  the  Upper  Helderberg,  but  they  also  have  close 


568  HISTORICAL   GEOLOGY. 

analogy  with  the  Oriskany  in  the  large  number  of  species  of  Platyceras,  Spirifer,  and 
Strophomenids.  (  J.  M.  Clarke,  on  the  Hercynian  Question,  42d  Rep. ,  Eep.  N.  Y.  State 
Mus.,  1889.) 

All  writers  have  made  the  Limuloids  of  the  Middle  and  Upper  part  of  the  era  good 
evidence  of  equivalency.  But  there  are  large  species  in  the  Lower  Silurian ;  and,  more- 
over, they  may  have  lived  in  brackish  or  fresh  waters,  as  some  facts  render  probable,  so 
that  they  really  have  very  little  chronological  value. 

According  to  Barrande,  the  following  are  characteristic  species  of  his  subdivisions, 
E,  F,  G,  H,  of  the  Upper  Silurian  of  the  Bohemian  basin :  — 

E.  Graptolitic  slates,  passing  above  into  limestone,  corresponding  to  the  Niagara 
period.    Many  Graptolites :  Halysites  catenulatus,  Leptcena  rhomboidalis,  Atrypa  (Dayia) 
navicula,  Pentamerus  Knightii,  Bhynchonella,  Spirifer,  Orthis.     Many  species  of  Ortho- 
ceras, and  others  of  Cyrtoceras,  Gomphoceras,  Trochoceras,  etc.  ;   Calymene,  Phacops, 
Lichas,  Cyphaspis,  Illcenus,  Cheirurus,  Acidaspis,  Proetus. 

F.  A  dark  limestone,  cherty  above  :  Favosites  Gothlandicus,  F.fibrosus  ;  Orthis  palli- 
ata,  Atrypa  reticularis,  A.  comata,  Pentamerus  galeatus,  Bhynchonella,  Spirifer,  Leptcena 
Verneuili;  Phacops,  Lichas,  Bronteus;  Tentaculites,  Goniatites. 

G.  A  cherty  or  impure  limestone,  with  an  intermediate  shaly  layer:  Atrypa  reticu- 
laris, Pentamerus ;  Tentaculites  ornatus  ;  Lituites,  Goniatites,  Orthoceras  Midas  ;  Phacops 
fecunda,  Dalmanites  Hausmanni,  Bronteus,  Cheirurus  Sternbergi,  Proetus,  Harpes. 

H.  Shale  and  sandstone:  Leptcena,  Orthoceras,  Lituites,  Goniatites,  Phacops  fecunda, 
Proetus,  Tentaculites. 

In  Russia,  on  the  Baltic,  south  of  the  Gulf  of  Finland,  the  four  subdivisions,  G,  H,  I, 
K,  have  afforded  the  following  species :  G.  Rhynchonella  affinis,  Strophomena  pecten, 
Orthis  Davidsoni,  Pentamerus  borealis,  Leperditia  Keyserlingi,  Phacops  elegans. 
H.  Dolomytes  and  Coral  limestone  :  Syringopora  bifurcata,  Favosites  Gothlandicus,  Haly- 
sites, Pentamerus  oblongus.  I.  The  Lower  Oesel  Zone,  dolomytes  =  Wenlock :  Euom- 
phalus  funatus,  Orthoceras  annulatum,  Spirifer  crispus,  Orthis  elegantula,  Leptcena 
transfer salis.  K.  The  Upper  Oesel  Zone,  limestones :  Pterinea  retroflexa,  Chonetes 
striatellus,  Spirifer  elevatus,  Beyrichia  tuberculata. 

In  New  South  Wales  occur  Favosites  Gothlandicus,  Heliolites  inter stinctus,  Calymene 
Blumenbachii,  Encrinurus  punctatus,  Phacops  caudata,  Atrypa  reticularis,  Strophomena 
pecten,  Pentamerus  Knightii,  P.  oblongus,  Meristella  tumida,  Orthoceras  ibex. 

American  Upper  Silurian  Species  Occurring  Elsewhere. 

Halysites  catenulatus,  Niagara,  Great  Britain  (Llandeilo,  Wenlock,  Aymestry),  Norway, 

Sweden,  Russia,  Eifel. 
Heliolites  pyriformis,   Niagara,   Great  Britain   (Wenlock,   Ludlow),   France,   Sweden, 

Russia,  Eifel. 

Favosites  Gothlandicus,  Bohemia. 

Eucalyptocrinus  decorus,  Niagara,  Great  Britain  (Wenlock),  Scandinavia. 
Orthis  elegantula,  Clinton,  Niagara,  Great  Britain  (Wenlock,  Ludlow),  Gothland. 
Orthis  hybrida,  Niagara,  Great  Britain,  Gothland. 
Orthis  biloba,  Niagara,  Great  Britain  (Wenlock),  Gothland. 
Plectambonites  transversalis,  Anticosti,  Great  Britain  (Wenlock),  Gothland. 
Leptcena  rhomboidalis,  Trenton,  through  Upper  Silurian,  into  Devonian,  Great  Britain 

(Wenlock,  Ludlow),  Sweden,  Russia,  Belgium,  Eifel,  France,  Spain. 
Strophomena  rugosa,  Niagara,  Helderberg,  Great  Britain  (Wenlock,  Ludlow),  Gothland, 

.  Russia,  Eifel. 

Spirifer  crispus,  Niagara,  Great  Britain  (Llandeilo,  Wenlock),  Gothland. 
Atrypa  reticularis,   Clinton,  Niagara,  Helderberg,   Great  Britain  (Wenlock,  Ludlow), 

Gothland,  Bohemia,  Russia  (Urals,  Altai). 


PALEOZOIC   TIME — UPPER   SILURIAN.  569 

Ccelospira  Scotica,  Clinton,  Great  Britain  (May  Hill). 

Hhynchonella  bidentata,  Niagara,  Great  Britain  (Wenlock). 

Hhynchotreta  cuneata,  Niagara,  Great  Britain  (Wenlock),  Gothland. 

Ehynchonella  Wilsoni,  Niagara,  Great  Britain  (Wenlock). 

Rhynchonella  Stricklandi. 

Pentamerus  galeatus,  Helderberg,  Great  Britain  (Wenlock,  Ludlow),  Eifel. 

Pentamerus  brevirostris,  Niagara,  Great  Britain  (Devonian). 

Pentamerus  oblongus,  Clinton,  Niagara,  Great  Britain  (Wenlock). 

Pentamerus  Icevis,  Great  Britain  (Wenlock).  —  P.  Knightii,  Great  Britain  (Ludlow). 

Anastrophia  interplicata,  Great  Britain. 

Bellerophon  bilobatus,  Trenton  to  Clinton,  Great  Britain  (Wenlock). 

Orthoceras  annulatum,  Clinton,  Niagara,  Great  Britain  (Wenlock,  Ludlow). 

Orthoceras  virgatum,  Niagara,  Great  Britain. 

Calymene  tuberculosa,  Niagara,  Great  Britain  (Bala,  Wenlock,  Ludlow),  Sweden,  Norway, 

Bohemia,  France. 

Homalonotus  delphinocephalus,  Clinton,  Niagara,  Great  Britain  (May  Hill,  Wenlock). 
Proetus  Stokesi,  Niagara,  Great  Britain  (Wenlock). 
Trinucleus  concentricus,  Trenton,  Hudson,  Great  Britain  (May  Hill). 
Tentaculites  ornatus,  Water-lime,  Great  Britain  (May  Hill,  Ludlow). 

Arctic  American  Upper  Silurian  Species  Occurring  Elsewhere. 

Stromatopora  concentrica,  Great  Britain,  Eifel. 

Halysites  catenulatus,  Great  Britain,  Norway,  Sweden,  Russia,  United  States. 

Favosites  Gothlandicus,  Great  Britain,  Sweden,  United  States. 

Favosites  polymorphus,  Great  Britain,  France,  Belgium,  Eifel. 

Receptaculites  Neptuni,  Great  Britain,  Belgium,  Eifel,  United  States. 

Orthis  elegantula,  Great  Britain,  Gothland,  Russia,  United  States. 

Atrypa  reticularis,  Great  Britain,  Gothland,  Urals,  Altai,  United  States. 

Pentamerus  conchidium,  Gothland. 

Encrinurus  Icevis  (?),  Gothland. 

Leperditia  Baltica,  Gothland. 

The  number  of  Lower  Llandovery  (top  of  Lower  Silurian)  species  that  are  known  to 
pass  into  the  Upper  Silurian  in  Great  Britain  is  104  in  45  genera,  out  of  a  fauna  of  204 
species  in  68  genera  (Etheridge). 

Devonian  Relations  of  the  Loicer  Helderberg  Fauna. 

This  subject  has  been  ably  discussed  by  J.  M.  Clarke,  in  the  42d  Annual  Report  of 
the  New  York  State  Museum,  1889,  under  the  title  "The  Hercynian  Question."  The 
terms  Hercynian  shales  and  Hercynian  fauna  were  first  given  by  E.  Kayser,  in  a  paper 
on  the  oldest  Devonian  formations  of  the  Hartz  Mountains,  to  the  second  of  four  for- 
mations in  the  region  —  the  "  Unterer  Wieder  Schiefer"  of  A.  Roemer.  It  contains  the 
oldest  fauna  of  the  Hartz,  and  was  pronounced  by  him  the  oldest  or  lowest  Devonian, 
and  also  the  equivalent  of  Barrande's  Upper  Silurian  divisions,  F,  G,  H. 

Clarke  gives  the  following  summary  of  the  history  of  Hercynian  ideas  :  "A.  ROEMER, 
in  1843,  regarded  the  fauna  in  the  Hartz,  in  its  typical  development,  as  Upper  Silurian ; 
but  subsequently  made  the  Cephalopod  facies  and  Brachiopod  facies  thereof  represent 
distinct  faunas,  the  former  Devonian,  the  latter  Silurian.  Beyrich,  in  1867,  believed  the 
two  faunas  of  Roemer  one,  and  suggested  their  equivalence  to  the  Bohemian  F,  G,  H,  and 
their  relation  to  the  Devonian.  KAYSER,  in  1878,  demonstrated  their  unity  and  Devonian 
character  and  regarded  them  as  the  lowest  Devonian,  and  as  representing  a  calcareous 


570  HISTORICAL   GEOLOGY. 

facies  of  the  Coblenzian  fauna  of  the  Rhine,  and  paralleled  them  with  the  Bohemian  faunas 
of  F,  G,  H,  taken  in  their  entirety  ;  in  1880  he  regarded  them  as  a  lower  (not  lowest)  Devo- 
nian fauna  and  still  as  a  calcareous  facies  of  the  Coblenzian  ;  but  in  1884  he  appears  to  have 
resumed  his  original  position  as  to  the  age  of  the  Hercynian,  and  modified  his  conception 
of  the  parallelism  with  the  Bohemian  fauna  by  removing  from  his  equivalent  the  lower 
portion  of  F.  ...  BARROIS,  in  1889,  made  the  Hercynian  lowest  Devonian,  but  dif- 
fered from  Kayser  (1878,  1880),  in  regarding  it,  not  as  a  calcareous  facies  of  the  Spirifer- 
sandstein  or  Coblenzian,  but  as  such  a  facies  of  the  older  Gedinnian,  considering  the 
Bohemian  G  as  its  equivalent." 

Kayser  concluded  further  that  the  Lower  Helderberg  formation  of  America  was 
Hercynian,  that  is,  lowest  Devonian,  contrary  to  the  views  of  Barrande,  who  had  made 
it  Upper  Silurian,  and  the  equivalent  of  the  three  divisions  in  his  Bohemian  system  just 
mentioned.  In  his  recent  Lehrbuch  (1891),  Kayser  leaves  the  Water-lime  in  the  Upper 
Silurian. 

Some  of  the  alleged  Devonian  characteristics  of  the  Lower  Helderberg  are  :  its  many 
species  of  Dalmanites  of  the  D.  Hausmanni  type  ;  its  species  of  Phacops,  of  the  type  of 
P.  fecunda,  and  of  Homalonotus,  of  the  type  of  H.  Vanuxemi ;  the  occurrence  of  many 
species  of  Platyceras;  the  special  Devonian  features  among  several  genera  of  Brachiopods 
and  Lamellibranchs.  On  the  contrary  the  formation  is  unlike  the  Hercynian  in  containing 
no  Goniatites,  and  like  the  Silurian  in  including  several  species  of  Cystideans.  Mr.  Clarke 
presents  in  his  paper  a  full  account  of  the  discussion  ;  and  while  he  unhesitatingly  refers 
the  Oriskany  formation  to  the  Devonian,  on  the  ground  of  its  fauna,  he  leaves  the  question 
as  to  the  Lower  Helderberg  without  a  decision.  No  attempt  is  made  to  compare  the 
American  fauna  with  that  of  the  Ludlow  beds  of  England,  which  is  really  the  typical 
fauna  of  the  later  part  of  the  Upper  Silurian  —  the  limits  of  the  Devonian  and  Silurian 
having  been  first  laid  down  by  Murchison  and  Sedgwick. 


GENERAL    OBSERVATIONS    ON    THE    UPPER    SILURIAN. 
GEOLOGICAL  AND  GEOGRAPHICAL  CHANGES  DURING  THE  UPPER  SILURIAN. 

NORTH    AMERICAN. 

In  the  region  of  the  Appalachian  geosyndine.  —  As  in  the  Lower  Silurian, 
the  successive  formations  have  their  greatest  thickness  along  the  Appalach- 
ian geosyncline,  and  at  the  same  time  limestones  were  the  prevailing  rocks 
of  the  continental  interior. 

The  thickness  of  the  argillaceous  beds  and  sandstones  of  the  East  indicate 
that  during  the  Niagara  period  the  deepening  of  the  geosyncline  amounted, 
in  Pennsylvania,  to  at  least  1500  feet  in  the  Medina  epoch,  over  2000  in  the 
Clinton,  1500  in  the  Niagara  and  Onondaga,  and  500  in  the  Lower  Helder- 
berg, —  in  all  5500  feet.  In  the  Onondaga  period,  the  subsiding  area  extended 
up  into  New  York,  west  of  its  center ;  for  it  was  there  that  the  Onondaga 
beds  were  formed  to  a  thickness  of  1000  feet,  with  evidence  in  many  parts 
of  shallow-water  origin.  In  the  Lower  Helderberg,  and  in  the  following 
Oriskany  periods,  the  greatest  thickness  of  the  beds  was  in  the  eastern  half 
of  the  state. 

No  sediments  for  rock-making  over  the  continent  from  the  Atlantic  Ocean. — - 
Although  the  Champlain  channel  between  the  St.  Lawrence  seas  and  those 
of  New  York  was  again  opened  wide  during  the  Lower  Helderberg  period,  it 


PALEOZOIC   TIME  —  UPPER   SILURIAN.  671 

still  gave  no  passage  to  coarse  sediments;   for  the  rocks  formed  over  the 
channel  were  mainly  limestone. 

So  again,  over  the  continental  border  from  New  York  to  Georgia,  since 
Upper  Silurian  rocks  are  unknown  along  the  border  region,  no  sediments  were 
supplied  to  the  interior  sea  across  this  border  from  the  Atlantic.  Upper 
Silurian  beds  may  exist  there  beneath  the  Cretaceous  or  Tertiary  formations, 
or  in  the  sea  bottom  outside ;  but  if  so,  the  broad  region  of  Archaean  making 
the  protaxis,  without  Upper  Silurian  beds,  lies  between.  The  Continental 
Interior  received  no  Atlantic  sediments. 

It  has  further  been  shown  that  the  Upper  Silurian  formations  of  New 
England  and  eastern  Canada  and  Newfoundland  were  in  general  made,  not 
on  the  borders  of  the  open  ocean,  if  so  at  all,  but  within  the  limits  of 
channels  or  bays  bounded  by  Archaean  ridges,  or  ridges  of  Archaean  and 
Lower  Silurian  rocks.  Of  Pacific  sea-border  beds  belonging  to  the  Upper 
Silurian  nothing  has  come  to  light.  In  the  Arctic  regions  the  rocks  occupy 
a  large  basin  or  area,  quite  distinct  from  that  of  the  Continental  Interior. 
Its  limits  are  unknown. 

Influence  of  the  Cincinnati  geanticline. — The  influence  on  the  eastern 
interior  sea  of  this  barrier  of  emerged  land  and  shallow  seas  was  strongly 
marked.  Owing  to  changes  in  level  that  were  in  progress,  shifting  the  areas 
of  deepest  water,  large  changes  were  made  from  time  to  time  in  the  courses 
of  the  tidal  movements,  in  the  character  of  the  depositions,  the  clearness  or 
foulness  of  the  water,  and  accordingly  in  the  character  of  the  life.  With 
clear,  deep  waters,  life  of  great  variety  abounded  and  limestones  were 
formed ;  but  with  sediment-laden  waters,  or  waters  half  freshened  by  contri- 
butions from  the  land,  the  living  species  were  only  those  that  could  survive 
under  such  adverse  circumstances. 

Abrupt  variations  in  the  rocks  and  the  life  become  thus  intelligible. 
It  is  hence  easy  to  understand  that  a  Niagara  epoch  might  be  followed, 
through  a  wide  shallowing  of  the  seas,  by  a  region  of  immense  salt-pans 
(evaporating  sea-border  flats)  over  a  large  part  of  New  York,  making 
the  Salina  group  of  rocks,  while  to  the  eastward,  southward,  and  west- 
ward a  tide-washed  region  existed,  —  that  of  the  Water-lime  group, — free 
from  saline  deposits  because  the  tides  had  access;  and  that  fresh-water 
and  brackish-water  flats,  containing  species  of  Eurypterids,  might  well 
have  been  a  feature,  at  the  same  time,  of  the  sea  borders.  Then  the  occur- 
rence of  a  slight  subsidence  would  account  for  clearer  seas  again,  for  a 
restored  fauna,  and  the  making  of  Lower  Helderberg  limestones,  and  also 
for  the  extension  of  the  limestones  over  eastern  New  York  to  Montreal  in 
the  St.  Lawrence  Channel,  and  southward  over  western  New  Jersey  and 
part  of  Pennsylvania.  Such  salt-evaporating  basins  are  due  to  local  condi- 
tions and  cannot  be  a  universal  feature  of  a  period. 

Large  shallow-water  and  emerged  areas  over  the  continent  characteristic  of 
the  Upper  Silurian  era.  —  The  absence  of  Upper  Silurian  formations  from 
much  of  the  region  west  of  the  Mississippi,  and  their  thinness  where  present, 


572  HISTORICAL   GEOLOGY. 

is  a  remarkable  feature  of  the  era.  Even  in  the  Laramide  Eange  of  southern 
British  America,  McConnell  found  the  Upper  Silurian  series  only  1500  feet 
thick ;  and  in  the  Wasatch  Eange,  according  to  King,  the  thickness  of  the 
whole  Silurian  is  but  1000  feet.  The  era  began,  as  the  Medina  rocks  show, 
with  shallow  waters  over  central  New  York,  and  probably  large,  emerged 
areas  east  of  the  Mississippi  as  well  as  west.  In  its  progress  through  the 
Clinton  epoch  there  were  still  shallow  waters  and  emerging  lands ;  for  the 
extensive  beds  of  iron  ore,  ranging  far  south  and  west  to  Wisconsin,  are 
evidence  of  great  seashore  flats  through  long  intervals  over  much  of  the 
eastern  half  of  the  continent.  In  the  Niagara  epoch  there  were  somewhat 
deeper  and  purer  waters  over  the  Interior  Continental  Seas,  but  the  areas 
were  not  of  very  wide  extent,  and  the  epoch  closed  through  the  coming  on 
of  another  period,  the  Onondaga,  in  which  again  great  seashore  flats  pre- 
vailed, with  feeble  submergences  or  emergences  where  any  occurred. 

The  length  of  this  period  of  great  briny  flats  and  salt  deposits  —  which 
were  100  miles  or  more  long  in  the  state  of  New  York,  and  twice  this  to 
Goderich,  on  Lake  Huron  —  cannot  be  estimated;  for  thinness  of  rocks 
means  nothing  as  regards  elapsed  time  where  a  region  is  undergoing  no 
oscillations  of  level,  or  only  those  of  extreme  slowness. 

The  prevailing  characteristic  of  the  continent  during  the  early  and  middle 
Upper  Silurian,  that  of  shallow  seas  and  emerging  seashore  flats,  continued 
on,  with  little  change,  through  the  closing  Lower  Helderberg  period;  for  the 
formations  are  unknown  over  the  Mississippi  basin  and  farther  west,  and 
have  their  greatest  extent  along  the  region  of  the  progressing  Appalachian 
geosyncline,  and  its  temporary  prolongation  northward  through  the  Hudson 
and  Champlain  depressions  to  Montreal. 

The  period  of  briny  fiats  unfavorable  to  aquatic  life.  —  Only  two  species  of 
the  Niagara  fauna,  the  widely  ranging  Leptcena  rhomboidalis  and  Atrypa 
reticularis,  are  known  to  occur  in  the  Lower  Helderberg  beds,  although  the 
epoch  which  intervened  was  only  one  of  muddy,  briny  flats.  But  the  remark 
applies  only  to  eastern  North  America,  for  nothing  has  been  ascertained  with 
regard  to  the  Onondaga  and  Lower  Helderberg  faunas  for  the  larger  part 
of  the  continent. 

No  upturning s  at  the  close  of  the  Upper  Silurian.  —  The  era  appears  to 
have  passed  and  ended  quietly.  It  had  slow  and  gentle  oscillations  in  level, 
like  other  geological  eras,  but  it  was  marked  with  no  great  upturning  in  its 
progress,  and  with  none  at  its  close.  The  Lower  Helderberg  formation 
graduates  into  that  of  the  opening  Devonian,  and  if  transferred  to  the 
Devonian,  the  statement  would  still  hold  true. 

The  eastern  continental  border  related  in  life  to  the  European. — In  Canada 
and  New  England  the  formations  of  the  Upper  Silurian  have  not  yet  been 
so  fully  distinguished  and  described  that  the  succession  of  events  for  this 
part  of  the  continental  border  can  be  deduced.  But  the  fact  that  the 
region  was  distinct  from  the  Interior  Continental  region  has  been  well  made 
out  from  the  Upper  Silurian  fossils,  by  Salter  and  Billings,  who  state  the 
following  facts :  — 


PALEOZOIC   TIME  —  UPPER   SILURIAN.  573 

In  the  beds  of  this  region  of  the  Cambrian  and  Canadian  periods  there 
are  Salterella  rugosa  Billings,  closely  like  the  Scottish ;  S.  Maccullochi 
Salter ;  Kutorgina  cingulata  B.,  said  by  Davidson  and  Hall  to  occur  in  the 
Lingula  flags;  Acrotreta  gemma  B.,  very  near  A.  subconica  Kutorga;  four 
species  of  Piloceras,  a  genus  described  from  Scotland,  but  not  known  in  the 
United  States;  Holometopus  Angelini  B.,  very  near  H.  limbatus  Angelin, 
of  Sweden;  Nileus  macfops  B.,  N.  scrutatus  B.,  N.  ajfinis  B.,  all  closely 
allied  to  N.  armadillo  Dalman;  Harpides  Atlanticus,  very  near  Angelin's 
H.  rugosus  of  Sweden.  In  beds  of  Hudson  age  there  are  Ascoceras  Cana- 
dense  B.,  A.  Newberryi  B.,  and  Glossoceras  desideratum  B.,  not  found  in  the 
United  States.  In  the  Upper  Silurian  there  are,  as  shown  by  Salter,  the 
British  species,  Rhynchonella  Wilsoni  Sow.,  Grammysia  triangulata  Salter, 
G.  cingulata  His.,  Platyscliisma  helicoides  Sow.,  Platyceras  Haliotis  Sow., 
Bellerophon  expansus  Sow.,  B.  carinatus  Sow.,  Orthoceras  bullatum  Sow.  (?), 
O.  ibex  Sow.,  Homalonotus  Knightii  Konig,  Phacops  Downingii  Salt. ;  to 
which  Billings  adds  Rhynchonella  Stricklandi  Sow.,  and  Lituites  Ameri- 
canus  B.,  very  near,  if  not  quite  identical  with  L.  giganteus  Sow.  Billings, 
who  furnished  the  above  list  of  species,  adds  that,  through  the  Cambrian 
and  Canadian  periods,  there  is  a  decided  European  tinge  in  the  life,  but  in 
the  Trenton  period  its  character  was  peculiarly  American.  Then  in  the  Hud- 
son epoch  there  was  again  a  European  tinge,  which  increased  in  strength 
through  the  Upper  Silurian. 

H.  M.  Ami  has  given  (1892)  a  list  of  163  fossils  from  the  Upper  Silurian 
beds  of  Arisaig,  Nova  Scotia,  and  states  that  a  closer  relation  exists  between 
the  fauna  and  that  of  the  Ludlow  rocks  of  Kendal  in  Westmoreland,  England, 
than  with  either  the  Silurian  rocks  of  Anticosti,  Ontario,  or  New  York. 

EUROPEAN. 

The  endogenous  growth  of  the  European  continent  during  the  Upper 
Silurian  era  is  manifest,  though  of  less  regular  progress  than  that  of  North 
America.  The  Upper  Silurian  formations  over  the  British  Isles  were  not 
on  the  outer  Atlantic  border,  but  on  the  opposite  side  of  a  border  region 
of  Archaean  and  Lower  Silurian  rocks,  and  this  inner  side  continued  to 
be  the  region  of  growth  to  the  end.  Moreover,  there  appear  to  have  been 
two  or  three  confined  and  parallel  troughs.  In  Scandinavia  and  Russia, 
part  of  France  and  the  Spanish  peninsula,  the  same  is  true.  All  the  Upper 
Silurian  rocks  of  Russia  are  the  work  of  an  Interior  Continental  Sea,  wi^h- 
out  oceanic  aid ;  and  this  great  Interior  Sea  extended  south  and  west  over 
Hungary  and  Austria  to  Bohemia  and  the  Alps.  The  Mediterranean  Sea 
is  related  to  the  continent  like  the  West  Indies  and  Mexican  Gulf  to 
America. 

The  progress  through  the  era  was  in  general  quiet ;  for  the  Upper  Silu- 
rian rocks  are  conformable  in  superposition.  They  are  horizontal,  or  very 
nearly  so,  over  the  great  interior  region  in  Russia  and  elsewhere.  Nearer  the 
ocean,  in  England,  the  rocks  to  a  considerable  extent  pass  regularly  upward 


574  HISTORICAL   GEOLOGY. 

into  the  Devonian.  But  in  the  western  part  in  Wales,  —  and  in  the  Lake 
region  to  the  north,  —  they  lie  unconformably  beneath  the  Old  Red  Sand- 
stone (Devonian),  proving  thereby  that  an  epoch  of  local  mountain- making 
in  that  region  closed  the  period.  Similar  evidence  of  disturbance  exists  in 
Ireland. 

BIOLOGICAL  PROGRESS. 

The  records  of  the  Upper  Silurian  era  add  to  the  terrestrial  fauna  the 
earliest  of  Arachnids,  or  Spiders,  in  the  form  of  Scorpions,  and  additional 
species  of  Insects.  The  former  are  in  the  successional  line  of  the  Euryp- 
terids,  whose  earliest  species  is  Lower  Silurian ;  the  Insects  are  structurally 
in  the  line  of  the  Myriapods,  although  no  antecedent  species  of  Myriapod  is 
yet  known.  The  Cockroaches  are  Orthopters,  and  species  of  imperfect 
metamorphosis,  like  the  Hemipters.  The  relations  of  the  above-mentioned 
groups  are  illustrated  in  the  course  of  the  General  Observations  on  the 
Paleozoic,  on  pages  721,  722. 

Among  marine  Invertebrates,  the  era  is  marked  by  a  large  diminution  in 
the  number  of  species  and  genera  of  Graptolites  and  Trilobites  —  Lower  Silu- 
rian characteristics  ;  by  an  abundance  of  Cystoids  and  Orthids  —  also  Lower 
Silurian  in  aspect ;  by  an  increase  in  the  number  and  size  of  the  Brachiopods 
of  the  families  of  Spiriferids,  Pentamerids,  and  Productids  —  Devonian  char- 
acteristics ;  by  an  increase  in  the  Pteropods  of  the  Conularia  type ;  by  an 
increase  in  the  number  of  Gastropods  of  the  Platyceras  (Capulus)  type,  and 
in  the  number  of  species  and  genera  of  Polyp-corals,  Crinoids,  and  Asterioids 
—  which  also  look  toward  the  Devonian;  by  an  increase  in  the  number  and 
variety  of  Eurypterids  and  Ceratiocarids — facts  having  the  same  bearing. 

Still  more  marked  is  the  advance  from  Entomostracans  to  Tetradecapod 
Crustaceans ;  and  far  beyond  this  is  the  appearance  of  Insects.  It  is  re- 
markable that  the  first  remains  of  Scorpions  should  have  been  found  in 
Europe  and  America  in  rocks  of  very  nearly  the  same  age.  But  it  may  be 
that  earlier  specimens  are  yet  to  be  found. 

Fishes,  the  only  Vertebrates  of  the  Upper  Silurian,  were  represented  by 
Placoderms,  the  mail-clad  type  that  first  appeared  in  the  Trenton  Period  of 
the  Lower  Silurian,  and  possibly  also  by  Selachians.  But  no  remains  of 
other  Ganoids  have  yet  been  found  in  the  beds,  although  reported  from  the 
Trenton.  Rarity  in  fossils  of  lime-secreting  aquatic  species  is  not  common. 
Remains  of  Chimseroids,  mostly  cartilaginous  species,  also  are  absent. 

CLIMATE. 

There  is  no  evidence  that  the  climate  of  America  was  roughened  by 
frigid  winds,  or  that  the  ocean  was  much  modified  in  temperature  by  polar 
currents.  The  species  living  in  the  waters  between  the  parallels  of  30°  and 
45°  were  in  part  the  same  with,  or  closely  related  to,  those  that  flourished 
between  the  parallels  of  65°  and  80°.  (See  page  544.)  From  this  life 
thermometer  we  learn  only  of  warm  or  temperate  seas. 


PALEOZOIC   TIME  —  DEVONIAN.  575 


DEVONIAN  ERA. 

SYNONYMY.  —  Old  Red  Sandstone  Series  (from  the  rocks  in  Scotland),  British  Geologists 
before  1839.  Devonian  system,  Sedgwick  and  Murchison,  in  a  paper  on  the  Classification 
of  the  older  rocks  of  Devonshire  and  Cornwall,  Ann.  Phil,  April,  1839.  Old  Red  Sand- 
stone, or  Devonian  system,  Lyell,  Elements  of  GeoL,  1841.  Devonian,  of  later  geologists, 
Systeme  Devonien,  or  Pe'riode  Devonienne,  Beudant,  D'Orbigny,  Lapparent.  Devonische 
Formation,  of  the  Germans.  Devonic,  International  Congress  of  Geologists. 

As  the  era  of  the  Upper  Silurian  passed  quietly  into  that  of  the  Devonian, 
no  mountain  range  marks  the  interval  between  them,  and  no  abrupt  transition 
is  apparent  in  the  rocks  or  in  the  world's  fauna.  The  Devonian  was  emi- 
nently a  transition  era  as  regards  land  vegetation,  but  the  culminant  time 
of  aquatic  Vertebrates  —  Fishes.  The  land  population  was  low  grade,  it  com- 
prising only  Myriapods,  Spiders  with  the  related  Scorpions,  and  Insects  ;  and 
not  the  higher  Insects,  since  there  were  no  conspicuous  flowers  over  the  land. 
Terrestrial  Mollusks  also  may  have  been  in  existence,  but  evidence  of  this 
has  not  yet  been  reported.  The  Devonian  seas  contained,  in  general,  similar 
Invertebrate  forms  to  those  of  the  Silurian,  but  with  proportionally  fewer 
Trilobites,  a  profusion  of  Corals  and  Brachiopods,  along  with  new  forms  of 
Cephalopods  in  the  Goniatites  and  related  species. 


NORTH  AMERICAN. 
GENERAL  FEATURES  OF   THE   CONTINENT. 

The  map  of  North  America,  representing  its  condition  at  the  commence- 
ment of  the  Upper  Silurian,  gives  a  good  general  idea,  so  far  as  has  been 
learned,  of  the  continental  seas  and  land  at  the  opening  of  the  Devonian  era. 
There  is  the  same  uncertainty,  or  error,  it  may  be  called,  with  regard  to  the 
emerging  lands  over  the  Western  Interior  and  Rocky  Mountain  region;  the 
map  fails  to  indicate  them,  because  the  limits  of  such  areas  have  not  been  fully 
ascertained.  These  limits  will  in  part  always  remain  in  doubt,  unless  deter- 
mined by  deep  borings;  because  absence  of  formations  from  the  region  of 
outcrops  about  Archaean  mountains  is  far  from  being  proof  of  absence  beneath 
the  plains  between  the  mountains,  or  50  miles  or  so  distant  from  the 
mountains.  It  is,  however,  almost  certain  that  in  the  Devonian  era  the 
Silurian  island,  covering  much  of  Missouri,  extended  southward  and  westward 
over  a  large  part  of  Arkansas  and  Texas,  and  beyond,  as  referred  to  on  page 
537.  The  Silurian  islands  of  Tennessee  and  the  Cincinnati  region  (C  and  T 
on  the  map,  page  536)  were  still  islands.  A  marked  feature  of  the  Continental 
seas  is  the  half-confined  Northeast  Bay,  of  the  Eastern  Interior;  and  it  has 
special  importance  in  this  era,  since  a  large  part  of  the  described  Devonian 
beds  were  deposited  within  it  and  owe  to  its  varying  conditions  their  charac- 
teristics. 


576 


HISTORICAL   GEOLOGY. 


UPPER, 
OR  LATER 
DEVONIAN. 


SUBDIVISIONS. 

{2.  CHEMUNG  EPOCH  :   that   of  the   Chenrnng 
group,  N.  Y.  Geol  Reports,  1842,  1843. 
1.  PORTAGE  EPOCH  :  that  of  the  Portage  group, 
N.  Y.  Geol  Reports,  1842,  1843. 

2.  HAMILTON  EPOCH:  that  of  the  Hamilton 
beds  with  the  Tully  limestone  in  places  at  top, 
N.  Y  Geol.  Reports,  1842,  1843. 

1.  MARCELLUS  EPOCH  :  that  of  the  Marcellus 
shales  (with  the  Goniatite  limestone  near  the 
bottom),  N.  Y  Geol.  Reports,  1842,  1843. 

2.  CORNIFEROUS  EPOCH  :  that  of  the  Cornif- 
erous  and  Onondaga  limestones,  N.  Y.  Geol.  Re- 
ports, 1842,  1843. 

1.  SCHOHARIE  EPOCH:  that  of  the  Schoharie 
grit  and  Cauda-galli  grit,  N.  Y  Geol.  Reports, 
1842,  1843. 

That  of  the  Oriskany  sandstone,  N.  Y.  Geol. 


MIDDLE 
DEVONIAN. 

3.  Hamilton 
Period. 

LOWER, 
OR  EARLY 
DEVONIAN. 

2.  Cornife-    1 
rous  Period.   | 

1.  Oriskany  J 
Period  :      | 

The  Devonian  formations  commence  in  eastern  North  America  with 
sandstones.  Then  follows  a  great  continental  limestone,  the  Corniferous. 
This  limestone  has  in  the  Devonian  era,  therefore,  a  position  corresponding 
with  that  of  the  Niagara  limestone  in  the  Later  Silurian.  Above  the  lime- 
stone there  is  a  great  thickness  of  shales  and  sandstones  with  but  little  lime- 
stone. To  the  eastward,  in  New  York  and  Pennsylvania  especially,  the  sea 
border  deposits  of  coarse  sands,  gravel,  and  pebble  beds,  of  great  thickness, 
which  were  in  progress  during  the  Upper  and  partly  the  Middle  Devonian, 
make  now  red  sandstone  and  conglomerate,  and  constitute  what  is  called  the 
Catskill  formation.  These  beds  have  been  heretofore  regarded  as  mainly  of 
subsequent  origin  to  the  Chemung,  and  have  been  referred  to  a  period  follow- 
ing it,  called  the  Catskill  period;  but,  as  explained  beyond,  they  are  now 
believed  to  be  a  cotemporaneous  formation  parallel  in  its  deposition  with  that 
of  the  off-shore  and  deeper  waters  of  the  Chemung  period,  or  Chemung  and 
Hamilton  periods,  to  the  westward. 

Over  the  Eastern  Interior  region  limestones  constitute  the  chief  part  of 
the  beds  of  the  earlier  half  of  the  era,  and  black  shale,  of  moderate  thickness, 
those  of  the  later  beds. 

The  three  divisions  of  the  Devonian,  the  Early,  Middle,  and  Later,  have 
been  named  by  H.  S.  Williams  (1894),  respectively,  the  Eodevonian,  Meso- 
devonian,  and  Neodevonian.  The  term  Erian  is  applied  to  the  Devonian  of 
North  America  by  iawson. 


PALEOZOIC  TIME  —  DEVONIAN.  577 

1.  ORISKANY  PERIOD. 

ROCKS  — KINDS   AND  DISTRIBUTION. 

The  Oriskany  sandstone  in  eastern  North  America  has  nearly  the  limits 
and  distribution  of  the  Lower  Helderberg  formation.  It  occurs  over  the  eastern 
half  of  New  York,  between  Cayuga  Lake  and  Albany,  and  reaches  northward 
to  Oriskany  Falls,  northeast  of  Utica,  having  a  thickness  seldom  exceeding 
20  or  25  feet.  It  overlies  the  Lower  Helderberg  in  Becrafts  Mountain,  and 
abounds  in  fossils.  It  extends  southward  along  the  Appalachian  region, 
with  increasing  thickness,  being  200  feet  or  more  at  Port  Jervis,  150  to  200 
feet  along  the  western  border  of  New  Jersey,  and  eastern  of  Pennsylvania, 
and  of  still  greater  thickness  in  western  Maryland  (at  Cumberland),  West 
Virginia,  and  Virginia.  It  occurs  also  in  eastern  Canada,  at  Gaspe,  and  in 
Maine  along  the  Gaspe-Worcester  trough,  over  Parlin  Pond  and  the  northern 
part  of  Moosehead  Lake,  where  it  is  reported  to  be  several  thousand  feet 
thick  (C.  H.  Hitchcock).  It  is  found  also  in  Ontario,  west  of  Niagara,  and 
in  southern  Illinois,  where,  in  Union  and  adjoining  counties,  its  maximum 
thickness  is  250  feet. 

The  rock  is  usually  a  rough  calcareous  sandstone,  or  arenaceous  limestone, 
becoming,  where  weathered,  porous  and  full  of  holes,  from  the  dissolving 
away  of  its  many  fossils  by  percolating  waters.  It  is  sometimes  cherty  lime- 
stone, a  pebbly  sandstone,  and  in  part  a  shale.  In  its  distribution,  its  great 
abundance  of  fossils,  and  its  usually  calcareous  or  semi-calcareous  character, 
it  is  widely  different  from  the  grits  which  follow  it,  and  bears  a  close  relation 
to  the  Lower  Helderberg  series  of  impure  limestones.  At  Becrafts  Mountain 
the  beds  represent  the  Lower  Oriskany,  and  the  rock  is  a  hard,  cherty, 
arenaceous  limestone.  A  similar  rock  exists  at  Port  Jervis. 

A  sandstone  containing  what  appear  to  be  Oriskany  fossils  has  been 
observed  by  C.  W.  Hayes  in  the  highly  disturbed  region  of  northern  Alabama, 
in  Frog  Mountain,  between  Weisner  and  Indian  mountains.  It  rests  on  Lower 
Silurian  and  Cambrian  unconf ormably ;  but  the  unconformability,  though 
extensive,  is  described  as  due  to  overlap.  No  intervening  Upper  Silurian 
beds  occur  in  the  region.  The  Clinton  group  (Kockwood  beds)  exists  to  the 
south,  but  not  at  that  locality  (1891,  ?94). 

The  geological  connections  of  the  Oriskany  are  with  the  Lower  Helder- 
berg formation,  its  beds  thickening  to  the  eastward  as  in  the  Lower  Helder- 
berg. It  is,  however,  pronounced  Devonian  in  its  fauna  and  flora,  and  hence 
belongs  in  the  Devonian  era. 

LIFE. 

The   Oriskany   fauna,  although   the   rocks   are   rarely  pure  limestones. 

included  a  few  Crinoids,  of  the  genera  Melocrinus,  Mariacrinus,  Technocrinus, 

Edriocrinus,  etc. ,  common  fossils  in  western  Maryland,  but  not  in  New  York ; 

some    Cystoids;    numerous   Brachiopods,   of    which  the    two    represented 

DANA'S  MANUAL  —  37 


578 


HISTORICAL   GEOLOGY. 


BBACHIOPODS.  —  Figs.  848,  a,  Spirifer  arenosus  ;  849,  Kensselseria  ovoides. 


on  this  page  are  characteristic ;  among  Gastropods,  a  dozen  or  more  species 

of  Platyceras;  Conularim,  one,  C.  lata,  over  five  inches  long;  a  few  Ortho- 

cerata;  Trilobites  of 

848  a  849.  the    genera    Homa- 

lonotus,  Dalmanites, 
and  others.  The 
Homalonotus  major, 
of  Whitfield,  had  a 
length  exceeding  15 
inches,  and  a  breadth 
of  5  inches.  Dal- 
manites dentatus,  of 
Barrett,  has  the  front 
ornamented  with  a 
range  of  large  trian- 
gular teeth,  and  is 
the  earliest  species 
of  this  type  of  Dal- 
manites. Acidaspis 
tuberculata  occurs 

here  and  also  in  the  Shaly  limestone  of  the  Lower  Helderberg. 

With  the  close  of  the  Oriskany  period,  the  Lower  Helderberg  conditions 

of  the  Eastern  Interior  ended.     The  deposits  no  longer  thickened  to  the 

eastward. 

Hall  remarks  on  the  close  relation  of  the  Oriskany  fauna  in  central  New  York  to  that  of 
the  Lower  Helderberg,  but  in  other  regions,  especially  in  Ontario  and  Maryland,  to  that 
of  the  overlying  Upper  Helderberg.  The  true  Oriskany  sandstone  or  Hipparionyx  fauna 
of  New  York  comprises  45  species  (Schuchert),  which  are  chiefly  large  Brachiopods, 
Lamellibranchs,  and  Gastropods,  with  an  almost  total  absence  of  Corals  and  Crustacea. 
In  contrast  with  this,  Beecher  and  Clarke  have  shown  that  the  Lower  Oriskany  fauna  of 
Becrafts  Mountain  and  to  the  southward  contains  more  than  120  species,  of  which  15  are 
Trilobites  and  about  10  are  Corals,  and  the  whole  fauna  is  transitional,  showing  the  pas- 
sage of  the  Lower  Helderberg  fauna  into  typical  Lower  Devonian. 

I.  C.  White  concluded,  from  his  observations  in  eastern  Pennsylvania  (1882), that  the 
beds  were  accumulated  on  the  borders  of  the  seas  in  which  the  Lower  Helderberg  lime- 
stones were  at  the  same  time  forming  in  clearer  waters,  thus  making  it  one  with  them  in 
period  of  origin.  The  beds  of  the  latter  often  pass  directly  into  the  Oriskany,  as 
if  they  constituted  it.  In  Virginia  there  is  the  same  close  relation  to  the  Lower  Helder- 
berg. It  is  to  be  observed,  on  the  other  hand,  that  the  beds  of  Becrafts  Mountain  overlie 
those  of  the  Lower  Helderberg.  At  the  Delaware  Water  Gap  the  rock  is  largely  a  shale  ;  in 
Maryland,  a  crumbling  sandstone,  from  loss  of  its  calcareous  part ;  at  Gaspe" ,  a  limestone, 
with  probably  a  part  of  the  underlying  sandstone  beds,  a  Eensselceria  having  been  found 
1100'  above  the  base  of  the  sandstones.  Oriskany  fossils  are  reported  also  from  the  head  of 
Tobique  River  in  New  Brunswick.  The  Nova  Scotia  strata  of  this  epoch  occur  at  Nictaux 
and  on  Moose  and  Bear  rivers.  They  include  a  thick  band  of  fossiliferous  iron  ore,  which 
is  an  argillaceous  deposit  at  Nictaux,  but,  owing  to  partial  metamorphism,  is  magnetic  iron 
ore,  and  partly  specular,  on  Moose  River.  The  Oriskany  beds  of  New  York  are  described 
in  the  N.  Y.  Geol.  Sep.  of  Vanuxem  and  Hall,  in  Hall's  Pal.  jRep.,  vols.  iii.  and  iv. ;  by 


PALEOZOIC  TIME  —  DEVONIAN.  579 

Beecher  and  Clarke  in  the  Am.  Jour.  Sc.,  1892  ;  of  eastern  Pennsylvania,  by  I.  C.  White 
in  Penn.  Geol.  Hep.,  G  6,  1882  ;  of  Illinois,  in  the  Geol.  Hep.,  111.,  by  Worthen,  vol.  iii. ; 
of  Canada,  in  Can.  Geol.  Rep.,  1863,  and  also  in  later  Annual  Reports.  Among  the 
Brachiopods  of  the  Oriskany  occur  the  genera  Orthis,  Stropheodonta,  Leptcena,  Hafines- 
quina,  Chonetes,  Leptostrophia,  Meristella,  Cyrtina,  Spirifer,  Hhynchonella,  Centronella, 
Cryptonella ;  also  the  genera  Hensselceria,  Eatonia,  Leptocoelia,  which  are  more  largely 
developed  in  the  Oriskany  than  in  any  other  period.  Orthis  hipparionyx  =  Hipparionyx 
proximus,  /Spirifer  arenosus,  S.  arrectus,  Leptoccelia  flabellites,  Cyrtina  rostrata,  Eens- 
selceria  ovoides  are  characteristic  species. 

The  Illinois  beds,  of  cherty  limestone,  have  afforded  Anoplia  nucleata,  Hhynchonella 
speciosa,  Eatonia  peculiaris,  Leptoccelia  flabellites,  Newberria  Condoni,  Amphigenia 
elongata,  Strophostylus  ?  cancellatus,  Platyceras  spirale,  and  other  species.  At  Becrafts 
Mountain,  the  species  include,  according  to  C.  E.  Beecher  and  J.  M.  Clarke,  six  species  of 
Dalmanites,  two  of  Phacops,  a  Homalonotus,  Cyphasphis,  Proetus,  Acidaspis  ;  a  Cirriped 
of  the  genus  Turrilepas;  corals  of  the  genera  Zaphrentis,  Homingeria,  the  Crinoid 
Edriocrinus  sacculus.  The  unusual  number  of  Trilobites  for  the  Oriskany  indicates 
apparently  clearer  waters  along  the  Hudson  River  valley  than  to  the  westward  along 
central  New  York.  The  Lower  Helderberg  species  obtained  are  Acidaspis  tuberculata  of 
the  Shaly  limestone,  a  Cyphaspis,  two  Dalmanites,  and  a  Phacops  of  L.  H.  type  ;  Tentacu- 
lites  elongatus  /  Orthis  perelegans,  and  O.  oblata  ?  of  the  Shaly  limestone  ;  Leptostrophia 
Becki,  Trematospira  multistriata,  of  the  Shaly  ;  a  Ccelospira,  Anastrophia ;  Eatonia 
medialis,  of  the  Shaly ;  a  Zaphrentis,  Shaly  in  type.  The  Devonian  forms  are 
Dalmanites  phacoptyx  (known  previously  only  from  .the  Upper  Helderberg  of  Ontario), 
a  Phacops,  Leptostrophia  perplana,  a  Chonetes  ?,  Hemitrypa  ?,  Fenestella  celsipora  of  the 
Corniferous.  At  Parlin  Pond,  in  western  Maine,  there  occur  Hensselceria  ovoides,  Lepto- 
ccelia flabellites,  Spirifer  arrectus  H.,  S.  pyxidatus  H.,  Stropheodonta  magniflca  H.,  Hhyn- 
chonella  oblata  H.,  Orthis  musculosa  H.,  Dalmanites pleuropteryx,  etc.  (Billings). 

See,  further,  on  the  relations  of  the  Lower  Helderberg,  Oriskany,  and  Devonian  faunas, 
the  remarks  on  page  569. 

2.  CORNIFEROUS  PERIOD. 

The  Corniferous  period  includes  two  epochs,  the  SCHOHARIE  and  the 
CORNIFEROUS.  To  the  former  belong  the  Cauda-galli  grit  and  the  Schoharie 
grit,  now  considered  cotemporaneous  formations;  to  the  latter,  the  Cor- 
niferous limestone. 

ROCKS  — KINDS  AND  DISTRIBUTION. 

The  rocks  of  the  Corniferous  period  in  New  York  have  their  greatest 
thickness  in  the  region  of  the  Eastern  Interior  Sea,  along  the  Appalachian  belt. 
The  Cauda-galli  grit,  a  dark  gritty  slate,  thickens  toward  the  Hudson,  being  50 
or  60  feet  thick  in  the  Helderberg  mountains,  and  100  to  150  feet  east  of  the 
Hudson  Eiver  in  Becrafts  Mountain,  near  Hudson ;  and  the  Schoharie  grit  is 
best  displayed  in  the  eastern  counties  of  New  York,  Albany,  Greene,  and 
Schoharie.  Neither  formation  is  found  to  extend  far  west  over  the  Oriskany 
beds  of  western  New  York  and  Ontario.  The  Cauda-galli,  like  many  seashore 
deposits,  is  almost  destitute  of  fossils ;  but  the  Schoharie  beds  abound  in  them, 
and  they  are  closely  related  to  those  of  the  following  Corniferous  epoch. 

The  Corniferous  limestone  —  so  called  by  Eaton,  with  reference  to  the 
hornstone  or  flint  often  imbedded  in  it  (from  the  Latin  comu,  horn)  —  extends 


580  HISTORICAL  GEOLOGY. 

from  near  the  Hudson  in  eastern  New  York,  westward  through  the  state,  and 
at  the  Niagara  River  forms  the  rapids  at  Black  Bock.  Thence,  it  is  con- 
tinued westward  through  Ontario  to  Ohio,  across  northern  Ohio,  and  to 
Mackinac  in  northern  Michigan.  It  thus  passes  beyond  the  limits  of  the 
Eastern  Interior  Sea  into  the  Central  Interior,  where  it  is  widely  distributed, 
occurring  in  Indiana ;  in  great  force  at  the  Falls  of  the  Ohio,  just  east  of 
New  Albany  and  Louisville  ;  also  in  Illinois  and  Kentucky ;  in  eastern  Iowa, 
near  Davenport,  as  a  bed  of  gray  to  buff  limestone  150  feet  thick,  resting  on 
Niagara  and  Trenton;  and  in  Missouri. 

The  limestone  is  commonly  light  gray  to  bluish  or  buff  (lightest,  which 
means  purest,  to  the  west)  ;  occasionally  it  is  blackish  and  rough  from  the 
abundance  of  hornstone  masses,  which  are  left  projecting  by  surface  wear. 

Much  of  the  rock  abounds  in  corals,  like  many  reef-rocks  of  modern 
coral  seas.  It  exhibits  its  coral-reef  character  grandly  at  the  Falls  of  the 
Ohio,  where  the  corals  are  crowded  together  in  great  numbers,  some  standing 
as  they  grew,  others  lying  in  fragments,  as  they  were  broken  and  heaped 
up  by  the  waves,  branching  forms  of  large  and  small  size  mingled  with 
massive  kinds  of  hemispherical  and  other  shapes.  Some  of  the  cup  corals 
(Cyathophylloids)  are  six  or  seven  inches  across  at  top,  indicating  a  coral 
animal  seven  or  eight  inches  in  diameter.  Hemispherical  compound  corals 
occur  five  or  six  feet  in  diameter.  The  various  coral-polyps  of  the  era  had, 
beyond  doubt,  bright  and  varied  coloring,  like  those  of  the  existing  tropics ;. 
and  the  reefs  were  therefore  an  almost  interminable  flower-garden. 

In  the  Canada-New-England  region  a  limestone  made  up  of  corals  occurs 
on  Lake  Memphremagog,  between  Vermont  and  Canada,  showing  that  coral 
reefs  flourished  there  also ;  and  other  localities  exist  to  the  eastward.  At 
Gaspe,  a  thick  limestone  formation  underlies  7036  feet  of  Devonian  sand- 
stone ;  and  about  800  feet  of  the  limestone  with  1000  feet  or  so  of  the 
overlying  sandstones  are  referred  to  the  Corniferous  period. 

Over  the  western  part  of  the  Continental  Interior,  beyond  the  Mississippi, 
at  Paleozoic  outcrops,  the  Carboniferous  beds  often  rest  directly  on  the 
Lower  Silurian,  or  the  Cambrian,  with  nothing  of  the  Devonian  between. 
This  is  so  at  the  Black  Hills,  in  Dakota,  and  in  central  Texas,  and  east  of 
the  Front  Eange,  in  Colorado.  Farther  west,  in  the  Eureka  district,  there 
are  6000  feet  of  Devonian  limestone  (Hague). 

In  the  Wasatch  Mountains  the  Devonian  is  made  by  King  2400  feet 
thick,  the  lower  1000  feet  consisting  of  the  "Ogden  quartzyte,"  and  the 
part  above  this  being  the  lower  portion  of  the  "  Wasatch  limestone,"  whose 
total  thickness  is  7000  feet.  Just  north  of  Montana,  in  British  America, 
there  are  1500  feet  of  Devonian  limestone. 

In  California,  Devonian  limestone  and  shales  occur  east  of  the  Sacra- 
mento in  Siskiyou  and  Shasta  Counties  (Diller  and  Schuchert). 

In  the  northern  part  of  British  America  Devonian  rocks  occur  along  the 
Mackenzie  River  (F.  B.  Meek,  from  the  collection  of  R.  Kennicutt)  ;  but 
the  fossils  yet  observed  are  those  only  of  the  Hamilton  and  later  Devonian, 


PALEOZOIC    TIME  —  DEVONIAN.  581 

so  that  the  presence  of  Corniferous  rocks  is  doubtful.  The  recent  map  of 
the  Canadian  survey  makes  a  Devonian  belt  (with  Carboniferous  beds) 
to  come  down  from  the  far  north,  along  by  the  summit  of  the  Rocky 
Mountains,  into  the  United  States. 

The  Corniferous  limestone  in  some  places  abounds  in  mineral  oil.  The 
oil  wells  of  Enniskillen,  western  Canada,  are  from  this  rock,  according  to 
T.  S.  Hunt  (1863)  ;  large  areas  are  covered  with  the  inspissated  bitumen. 
At  Eainham,  Canada,  on  Lake  Erie,  shells  of  Pentamerella  arata  are  some- 
times rilled  with  the  oil ;  and  in  other  localities  Corals  of  the  genera 
Hellopliyllum  and  Favosites  have  their  cells  full,  in  some  layers  of  the 
limestone,  while  empty  in  other  layers. 

The  facts,  with  regard  to  the  distribution  of  the  Devonian  formations  in  North 
America,  the  history  of  geological  discovery  in  connection  with  them,  their  geological 
relations  and  distinctive  features,  are  clearly  and  fully  presented  by  H.  S.  Williams,  in 
Bulletin  No.  80  of  the  U.  S.  Geol.  Survey,  and  partly  from  personal  observation. 

Interior  Continental  and  Appalachian  region.  —  The  Cauda-galli  grit  in  New  York 
is  a  drab  or  brownish  argillaceous  sandstone,  often  shaly  and  crumbling.  From  eastern 
New  York  it  continues  along  the  northwestern  boundary  of  New  Jersey,  and  the  eastern 
of  Pennsylvania,  where  it  is  a  gritty  slate,  and  is  in  some  places  400'  to  500'  thick. 

The  Corniferous  limestone  in  New  York  consists  of  two  members,  — the  gray  Onondaga 
limestone,  or  lower  part,  and  the  darker  Corniferous,  or  upper.  But  the  two  alternate 
with  one  another,  and  no  distinction  is  now  recognized.  The  limestone  is  sometimes 
oolytic.  Its  thickness,  as  found  where  boring  for  oil  and  salt,  is  commonly  100'  to  160'; 
at  Ithaca  only  78'.  Along  the  Delaware,  south  of  Port  Jervis,  N.Y.,  to  the  New  Jersey 
boundary,  the  thickness  is  about  250' ;  the  flint  nodules  are  from  an  inch  to  a  foot  in 
diameter,  and  often  contain  shells  and  remains  of  Crinoids. 

In  Ohio  it  occurs  on  both  sides  of  the  Cincinnati  geanticline,  and  also  along  the 
shores  of  Lake  Erie.  On  Kelleys  and  Middle  islands,  in  this  lake,  the  beds  have 
the  characters  of  old  coral  reefs,  like  those  at  the  Falls  of  the  Ohio.  It  corresponds,  it  is 
supposed,  to  the  whole  Upper  Helderberg  period ;  two  divisions  are  made  out,  —  the 
lower,  named  the  Columbus,  or  Sandusky,  and  the  upper,  the  Delaware  limestone. 

In  Missouri,  siliceous  and  sandstone  layers  alternate  with  the  limestone. 

Rocky  Mountain  and  Pacific  border  regions.  —  In  the  Eureka  district,  the  thickness, 
according  to  A.  Hague,  is  8000' ;  the  lower,  6000',  limestone  (see  page  592)  ;  and  the 
rest,  shales.  Lower  Devonian  fossils  exist  in  the  lower  part  for  at  least  500',  and  Upper, 
in  the  upper  portion  ;  but  no  subdivisions  could  be  marked  off.  The  Eureka  district 
appears,  therefore,  to  be  the  center  of  one  of  the  extra  thick  Devonian  basins,  like  those  of 
the  Appalachian  region,  and  Gaspe  of  eastern  Canada,  on  the  St.  Lawrence  Gulf. 
How  far  south  or  north  the  thick  beds  continue  is  not  known.  To  the  north,  in  the 
Tucubit  Mountains,  Devonian  occurs. 

In  Arizona,  in  the  Kanab  Canon  (1121°  W.),  the  whole  Devonian  is  only  100'  thick 
(Walcott). 

In  the  Wasatch  region,  the  "  Ogden  quartzyte  "  is  referred  to  the  Devonian,  by  King, 
who  found  it  at  Ogden  Canon  1200'  to  1400'  thick,  at  Cotton  wood  Canon  1000',  and 
at  some  points  in  Middle  Nevada  800'  to  900'.  In  the  Wasatch  Mountains,  the  lower 
1400'  or  more  of  the  overlying  Wasatch  limestone  (7000'  thick)  is  Devonian,  it  affording 
fossils  of  the  Upper  Helderberg,  Genesee,  and  Chemung.  See  King,  Geol.  40th  Par., 
page  236. 

In  the  Laramide  range  of  the  southern  part  of  British  America  occur  1500'  of  Devonian 
limestone  (McConnell). 


582 


HISTORICAL   GEOLOGY. 


LIFE. 

PLANTS.  —  Among  Algae,  or  Seaweeds,  the  most  remarkable  is  the  Spi- 
rophyton  Caudagalli.  Fig.  850  represents  a  fragment  of  the  plant.  The 
broad  blade  of  the  seaweed  grows  spirally  about  the  central  axis,  much 
like  that  of  the  erect  Alaska  seaweed,  Thalassophyllum  clathrus.  The  Nema- 
tophyton  (Dawsoii),  Fig.  851,  is  a  tree-like  Fucoid.  The  specimen  was  found 
in  the  lower  part  of  the  Devonian  of  Gaspe,  Canada,  where  the  stems  are 


852. 


Fig.  850,  Spirophyton  Caudagalli ;  851,  Nematophyton  Logani  (x|)  ;  852  o,  6,  c,  fruit  of  Charse?    Figs,  from 

Hall,  Dawson,  and  Knowlton. 


sometimes  three  feet  in  diameter.  The  presence  of  Charce,  water-plants  of 
simple  cellular  structure  (inferior  to  Mosses,  but  Equiseta-like  in  habit,  and 
now  common  in  marshy  places),  has  been  rendered  probable  by  the  discovery 
(first  made  by  F.  B.  Meek)  of  minute  calcareous  fossils  resembling  their 
fruit  (spore-cases)  (Figs.  852  a,  b,  c,),  in  the  Corniferous  limestone  of  Ohio, 
and  in  the  cellular  chert  at  the  Falls  of  the  Ohio,  near  Louisville. 

The  hornstone,  or  chert,  in  the  Corniferous  limestone,  as  shown  by 
M.  C.  White,  is  full  of  microscopic  plants  from  -^-^  to  -^  of  an  inch 
in  diameter ;  and  with  them  occur  sponge-spicules  and  teeth  of  Annelids. 
Fig.  853 :  a  to  e  are  Xanthidia,  spore-cases  of  Desmids  (page  437)  ;  /,  g, 
conferva-like  filaments,  made  of  a  series  of  cells ;  i,  a  Diatom.  Besides 
these  there  are  siliceous  spicules  of  sponges,  Figs,  j,  Jc,  I,  m,  n;  and  o,  p 
represent  portions  of  jaws  of  Annelids.  The  mass  of  the  hornstone  was 
probably  made  out  of  siliceous  sponge-spicules  and  Diatoms. 


PALEOZOIC   TIME  —  DEVONIAN. 


>83 


The  higher  Cryptogams,  or  Acrogens,  are  represented  by  Lycopods,  or 
Ground  Pines,  Ferns,  and  Equiseta. 

To  the  Lycopod  tribe  are  referred  species  of  PsUophyton,  similar  to  those 
of  the  Oriskany  period ;  portions  of  the  plant  are  shown  in  Figs.  854  a,  6,  and 


853. 


MICROSCOPIC  ORGANISMS  IN  HORNSTONE.  —  Figs,  o-i,  Protophytes  ;  j-n,  spicules  of  Sponges  ;  o,  p,  Annelid  jaws. 

its  fructification  in  c,  d.  They  were  one  to  three  feet  high.  The  species 
differ  from  the  common  Ground  Pine  in  having  the  leaves  on  the  stems  nearly 
wanting,  and  also  in  having  the  axis  made  up  of  scalariform  vessels,  and  the 
spore-cases  (fruit,  c,  d)  usually  in  pairs  on  short  pedicels. 


854-857. 


855 


-04 


LYCOPODS.  —  Figs.  854  a,  6,  Psilophyton  princeps ;  c,  d,  same,  fruit ;  855  a,  Lepidodendron  Gaspianum  (1) ;  6, 
same,  showing  surface  scars  of  lower  part  of  stem.  FERNS.  —  Fig.  856,  Sphenophyllum  vetustum  (1)  ;  857, 
stem  of  tree  fern,  Caulopteris  antiqua  (x  J).  Figs.  854,  855,  Dawson  ;  856,  857,  Newberry. 

The  Corniferous  limestone  of  Ohio  has  afforded  the  Ferns,  Figs.  856  and 
857,  described  by  Newberry.     The  latter  is  part  of  the  trunk  of  a  tree  fern 


584 


HISTORICAL   GEOLOGY. 


of  the  genus  Caulopteris ;  and  G.  advena  Newb.  is  the  name  of  another 
species.  The  trunks  of  both  are  three  to  four  inches  in  diameter.  Newberry 
states  that  these  tree  ferns  probably  grew  over  the  region  of  the  Cincinnati 
uplift — then  an  island  (C,  map,  page  412  or  536). 

Spores  and  spore-cases  (sporangites)  have  been  reported  from  the  lime- 
stone of  Ontario  County,  N.Y.  As  described  by  J.  M.  Clarke  they  are  -^^ 
and  -£$  of  an  inch  in  diameter ;  he  suggests  that  they  may  be  from  Rhizocarps 
(the  lowest  of  Acrogens)  of  the  genus  JSalvinia  (p.  436),  and  they  are  referred 
to  the  species  Protosalvinia  Huronensis  of  Dawson. 

ANIMALS. — The  Upper  Helderberg  period  was  eminently,  as  has  been 
stated,  a  coral-reef  period,  but  besides  corals,  it  abounded  also  in  species  of 
other  tribes  of  invertebrate  life  characteristic  of  Paleozoic  time. 

1.  Sponges.  —  The  existence  of  Sponges  is  indicated  by  the  presence  of 
their  siliceous  spicules  in  the  hornstone,  two  slender  forms  of  which  are 
shown  in  Figs.  853  j,  Jc,  and  others  in  I,  m,  n.  Besides,  there  are  species  of 
Astrceospongia  and  Hindia.  There  are  also  several  species  of  Stromatopora, 
and  the  last  known  in  America  of  Receptaculites. 

858-864. 


POLYPS.— Fig.  858,  Zaphrentis  gigantea;  859,  Z.  Rafinesquii ;  860,  Phillipsastrea  Verneuili ;  861,  861  a,  Cyatko- 
phyllum  rugosum  ;  862,  Favosites  Goldfussi ;  863,  Syringopora  Maclurii ;  864,  Romingeria  cornuta.  Figs. 
858,  860,  862,  Edwards  and  Haime ;  859,  861,  Meek  ;  863,  Yandell  and  Shumard  ;  864,  Billings. 

2.  Polyp-corals.  —  Figs.  858  to  864  represent  a  few  of  the  many  Corals: 
859  shows  the  radiated  cup-shaped  termination  to  which  the  name  Cyatlw- 
phylloid  (from  *ua0os  cup,  and  <£vAAoi/,  leaf)  refers ;  858  has  both  extremities 
broken  off,  but  exhibits  the  interior  radiation.  Fig.  862  represents  a  portion 


PALEOZOIC   TIME  —  DEVONIAN. 


585 


865. 


of   a  common  species  of  Favosites  (honey-comb  Coral,  named  from  favus, 
honey-comb},  which  is  sometimes  in  hemispheres  five  feet  across;  860,  part  of 
the  surface  of  a  PhilUpsastrea,  a  common  massive  Coral,  and 
861,  a  fragment  of  a  species  of  Cyathophyllum  ;  863,  a  group 
of  clustered  tubes  scarcely  radiated  within,  of  the  genus 
Syringopora,  broken  from  what  was  once  a  convex  hemi- 
spherical mass  of  branching  tubes ;  864,  a  creeping  tube, 
having  cells  at  intervals. 

3.  Echinoderms.  — Besides  true  Crinoidsof  several  species, 
some  of  them  of  very  large  size,  there  were  the  Blastoids  one 
of   which   is   represented  in  Fig.  865.     Though  ovoidal  in 
form,  it  is    related  to  the  pentagonal    Pentremites   of  the 
Lower  Carboniferous. 

4.  Molluscoids. — Brachiopods  were  very  numerous;  and  Figs.  866  to  870 
represent  common  species.     The  Terebratula  family,  the  most  abundant  in 
species  in  existing  seas,  has  its  species ;  Fig.  870  is  one  of  them :  it  shows 
the  opening  at  the  beak. 

866-870. 


Nucleocrinus  Ver- 
neuili.     Meek. 


BBACHIOPODS.  —  Figs.  866,  S6T,  Spirifer  acuminatus ;  868,  S.  gregarius ;  869,  Productella  subaculeata;  870,  Cryp- 
tonella  lens.     Figs.  866  to  868  by  Meek ;  869,  870,  Halft 

5.  Mollusks. —  The  few  Lamellibranchs  described  include  the  following 
kinds,  with  species  of  the  Avicula  family  and  others. 


871. 


872. 


LAMELLIBRANCHS. —  Fig.  871,  Paracyclas  proavia  ;  872,  Conocardium  cuneus,  Meek. 

Among  Gastropods  occur  many  species  of  the  genus  Platyceras,  one  of 


586  HISTORICAL  GEOLOGY. 

which,  covered  with  spines,  is  represented  in  Eig.  873;  also  species  of 
Bellerophon,  Euomphalus,  Pleurotomaria,  Murchisonia,  Lower  Silurian  genera 
that  continue  through  the  Devonian,  into,  and  part  of  them  beyond,  the  Car- 
boniferous. Among  Cephalopoda  there  are  species  of  Orthoceras,  Gompho- 
ceras,  Cyrtoceras,  and  the  last  known  of  Trochoceras,  a  Silurian  type ;  also  the 
first  known  of  American  Goniatites  —  G.  mithrax  H.  (Fig.  874),  and  a  variety 

874. 


873. 


Fig.  8T3,  Platyceras  dumosum ;  Meek.    Fig.  874,  Goniatites  mithrax  ;  Hall. 

of  G.  discoideus  H.  being  reported  from  Ohio.  The  Goniatites  differ  from 
species  of  the  Nautilus  family  in  having  the  siphuncle  ventral,  and  the  mar- 
gin of  the  septa  deeply  flexed.  Tentaculites  of  large  size  also  occur,  and  the 
related  genus  Styliolina  (Fig.  916). 

6.  Crustaceans.  —  Trilobites  of  the  Lower  Silurian  genera,  Calymene  and 
Dalmanites,  and  of  the  Upper  Silurian,  Homalonotus,  Lichas,  Phacops, 
Proetus,  Cyphaspis,  are  most  common.  Under  some  genera  there  is  a  large 
diversification  of  form  in  ornamented  heads  and  pygidia.  The  following 
figures  from  Hall  and  Clarke  illustrate  some  of  the  forms  from  the  beds  of 
the  Early  and  Middle  Devonian.  Figs.  875,  876  are  heads  of  species  of 
Dalmanites ;  877,  878,  pygidia  of  species  of  the  same  genus  ;  879,  the  head  of 
an  Addaspis;  880,  part  of  a  pygidium  of  another  Acidaspis;  881,  882,  heads, 
of  species  of  Lichas;  883,  part  of  a  pygidium  of  a  Lichas;  884,  pygidium  of 
a  Proetus. 

The  most  extravagant  of  all  is  Lichas  grandis  H.,  which  had  a  pygidium 
four  inches  broad  armed  with  seven  thorny  spines  1^  to  2-1-  inches  long,  and  a 
grossly  protuberant  warty  head,  with  a  stout  •  spine  by  the  side  of  each 
eye.  The  extremity  of  the  pygidium,  restored  from  an  imperfect  specimen, 
is  represented  in  Fig.  883.  In  contrast  with  these,  other  species  of  Dalman- 
ites and  Lichas  are  very  plain.  Those  of  Proetus  (Fig.  884)  are  all  prim- 
looking  species,  with  evenly  curving  outline  before  and  behind. 

Crustaceans  of  the  Phyllopod  and  Ostracoid  types  are  rare.  But  Barnacles 
of  a  peculiar  kind  occur,  imbedded  to  their  upper  surfaces  in  the  Corals  of 


PALEOZOIC   TIME  —  DEVONIAN. 


587 


'the  old  coral  reefs,  precisely  like  related  kinds  in  corals  of  the  present  day. 
The  related  species  now  living  are  free-swimming  animals  in  their  young 
state ;  the  free  stage  is  ended  by  the  animal's  coming  to  rest  on  the  surface 


875-884. 


Fig.  875,  Head  of  Dalmanites  selenurus ;  876,  id.  D.  regalis  ;  877,  pygidium  of  D.  aspectans  ;  878,  id.  D.  Boothi  of 
the  Hamilton  beds ;  879,  head  of  Acidaspis  callicera ;  880,  portion  of  the  pygidium  of  Acidaspis  Komingeri 
restored  (x  £)  ;  881,  "  head  "  of  Lichas  gryps  ;  882,  id.  Lichas  hylaeus  ;  883,  posterior  extremity  of  pygidium, 
restored,  of  Lichas  grandis,  from  the  Schohario  grit ;  884,  pygidium  of  Proetus  crassimarginatus,  from  the 
Corniferous  limestone.  Hall  and  Clarke. 

of  a  living  Coral ;  and  once  there,  it  stays  and  forms  a  dwelling  cavity  lined 
with  shell  within  the  growing  Coral,  —  a  case  of  commensalism,  not  parasit- 
ism, it  receiving  lodging,  not  board.  Similar  Barnacles  —  Palceocreusia 
Devonica  of  Hall — were  commensals  of  Devonian  Corals,  showing  that  the 
practice  is  an  ancient  one. 

7.  Fishes.  —  Fishes  are  the  only  Vertebrates  known.  The  species  dis- 
covered in  the  Corniferous  limestone  are  :  (1)  Placoderms  ;  (2)  Dipnoans,  or 
Lung-fishes;  (3)  Ganoids;  (4)  Chimaeroids ;  (5)  Selachians,  or  Elasmobranchs 
(Sharks).  The  Placoderms  include  two  species  of  Cephalaspis,  —  one  from 
Gaspe  (Fig.  885),  and  the  other  from  Campbellton,  New  Brunswick  (Fig.  886, 


588 


HISTORICAL   GEOLOGY. 


its  head-shield).  The  surface  of  the  former  is  (as  usual  with  the  species) 
covered  with  small  tubercles  (Fig.  885  a),  while  the  latter  has  a  minutely 
pitted  surface.  A  restored  figure  of  a  foreign  species  is  shown  on  page  557. 


885. 


PLACODERMS. — Fig.  885,  Cephalaspis  Dawsoni  (x  |),  Lankester;  a,  tubercles  of  surface;  886,  C.  Campbell- 

tonensis  (x  £),  Whiteaves. 

The  posterior,  or  caudal  extremity,  of  the  C.  Dawsoni  is  so  very  short, 
relatively  to  the  breadth  of  head,  that  the  fish  must  have  been  poor  at 
sculling  —  its  chief  means  of  locomotion.  Any  relation  to  the  Trilobites 
is  set  aside  by  the  tubercular  surface.  Lankester  states  that  it  belongs  to 
the  subdivision  of  the  genus  which  he  calls  EncepJialaspis. 


887-889. 


889. 


887. 


DIPNOANS.  —  Fig.  88T,  Coccosteus  occidental  (x£)  ;  888,  Macropetalichthys  Sullivan ti  (x|-iV) ;  889,  Acanthaspis 

armata  (x  |).     From  Newberry. 

Among  the  Dipnoans  of  the  period  there  was  a  species  of  Coccosteus, 
(7.  occidentalis  of  Newberry  j  only  the  posterior  dorsal  plate  (Fig.  887)  is 
known ;  its  surface  is  in  part  fine-tuberculate.  Fig.  888  represents  the 


PALEOZOIC   TIME  —  DEVONIAN. 


589 


head-shield  of  another  large  Dipnoan;  its  length  in  some  specimens  is  16 
inches,  indicating  a  fish  of  large  size.  The  peculiar  spine-bearing  plate 
shown  in  Fig.  889  is  of  uncertain  relations. 

Ganoids  existed  of  formidable  size  and  dental  armature.  In  one  of  them, 
Onychodus  sigmoides,  the  mandible,  or  jaw  (Fig.  890),  was  14  inches  long,, 
and  the  head  18  inches.  At  the  extremity  of  the  lower  jaw  there  were  very 

890-892. 


GANOIDS.  —  Fig.  890,  mandible  of  Onychodus  sigmoides  (x£);  890  a,  one  of  the  large  teeth  at  the  extremity 
of  the  mandible  (xf).  CHLM^EROID  SELACHIAN.  —  Fig.  891,  Khynchodus  secans,  upper  tooth;  891  a,  &,. 
extremities  of  upper  and  lower  mandibles  in  natural  position.  FEN-SPINE  OF  A  SELACHIAN.  —  Fig.  892,. 
Machaeracanthus  sulcatus  (x  f).  Figs.  890,  891,  Newberry  ;  892,  Hall. 

few  very  large  teeth;  and  one  of  them,  nearly  half  the  natural  size,  is 
represented  in  Fig.  890  a. 

To  the  Chiinaeroids  are  referred  the  species  of  Rhynchodus,  having  4 
large,  beak-like  teeth,  two  in  each  jaw.  One  of  these  teeth  is  shown,  natural 
size,  in  Fig.  891.  The  relative  positions  of  the  upper  and  lower  jaws  at  the 
extremity  is  shown  in  Figs.  891  a,  b. 

The  Selachians  or  Sharks  of  Cestraciont  type  were  represented  by  species 
of  Psammodus.  One  of  the  spines  of  a  Shark,  probably  from  the  dorsal  fin, 
is  represented  in  Fig.  892 ;  the  length  of  this  spine  is  4  to  6  inches ;  but  that 
of  another  Ohio  species  is  20  inches. 

The  Nevada  Devonian.  —  In  the  Devonian  of  Nevada,  where  a  limestone 
6000  feet  thick  represents  nearly  the  whole  era,  the  Lower,  Middle,  and 
Upper  Devonian,  out  of  the  144  species  described  by  Walcott,  more  than 
half  occur  also  in  the  New  York  Devonian,  a  number  in  the  Iowa  that  are 


590  HISTORICAL   GEOLOGY. 

not  known  in  New  York,  besides  two  at  Mackenzie  River.  But  in  Nevada, 
10  per  cent  occur  in  both  the  Lower  and  Upper  500  feet  of  the  limestone ; 
and  11  per  cent  of  the  Lower  Devonian  are  known  only  in  the  Middle  or 
Upper  of  New  York.  Many  species,  therefore,  were  in  existence  over  the 
central  and  west-central  portion  of  the  continent  before  they  reached,  by 
migration,  the  shallower  waters  of  New  York  and  Pennsylvania  on  the 
eastern  border  of  the  Continental  Interior.  The  species  include  about  25  of 
Corals,  numerous  Brachiopods,  Lamellibranchs  and  Gastropods,  very  few 
Cephalopods,  Trilobites  and  Crustaceans,  and  no  Eurypterids  or  Fishes. 

Characteristic  Species. 

PLANTS.  —  On  Nematophyton  and  other  Devonian  plants  see  Dawson's  Cr.  Hist. 
Plants,  1888 ;  Trans.  Boy.  Soc.  Can.,  1889  ;  also  on  other  Devonian  (Brian)  Flora, 
the  Report  in  the  G-eol.  Survey  of  Canada,  1871 ;  also  earlier,  Q.  J.  Greol.  Soc.,  vols.  xv. 
xviii.,  xix.,  xxvii.  Dawson  also  reports  a  species  of  Leptophlceum  from  the  Lower  Gasp6 
beds  or  Upper  Helderberg.  Drepanophycus  of  Goppert  (1852),  described  as  a  seaweed, 
has  been  shown  to  be  the  same  as  Psilophyton.  The  supposed  fruit  of  Chara  is  still  of 
doubtful  nature.  See  Knowlton,  Am.  Jour.  Sc.,  xxxvii.,  1889. 

ANIMALS.  1.  Spongiozoans. — Species  of  Astrceospongia,  and  Hindia;  Ischadites 
bursiformis  H.,  Schoharie  grit;  Stromatopora ponderosa  Nich.,  Ohio;  Sy ring ostroma  den- 
sum  and  8.  columnare  Nich.,  Ohio. 

2.  Actinozoans.  —  Fig.  858,  Zaphrentis  gigantea  Ral,  and  859,  Zaph.  Bafinesquii  E. 

6  H.,  from  the  Falls  of  the  Ohio,  Z.Edwardsi  Nich.^Ohio,  Z.  prolifica  B.,  Ohio  ;  another 
Coral,  of  the  genus   Chonophyllum  (C.magnificum  B.),  has  a  diameter  at  top  of  6  or 

7  inches ;    it  is  from  Walpole,    Canada  West.      Fig.   860,   Phillipsastrea    Verneuili  E. 
&  H.,  P.  gigas  Owen,   Iowa,  Ohio;   Cystiphyllum  Americanum  E.  &   H.,  Heliophyllum 
Halli,  E.  &  H. ;  Fig.  861,  Cyathopyllum  rugosum  H.,  fragment  from  a  large  mass,  Falls 
of  the  Ohio ;  Fig.  862,  Favosites  G-oldfussi  D'Orb.,  Falls  of  the  Ohio,  a  fragment ;  F.  tur- 
binatus  B.,  Canada,  Ohio;  Fig.  863,  Syringopora  Maclurii  B.,  Canada,  Ohio;  Fig.  864, 
Bomingeria  cornuta  B.,  from  Canada. 

3.  Hydrozoans.  — Of  the  genus  Dictyonema. 

4.  Echinoderms. —  Species  of  Dolatocrinus,  Megistocrinus.   Of  Blastoids  (Pentremites), 
Fig.  865,  Nucleocrinus  Verneuili  L.  &  C. 

5.  Molluscoids.  —  (a)  Bryozoans  are  represented  by  many  species  of  Fenestella  and 
other  genera. 

(6)  Brachiopods.—  Figs.  866,  867,  Spirifer  acuminatus,  Con.,  N.Y.,  Ohio,  Ind.  ;  Fig. 
868,  Spirifer  gregarius  Clapp,  N.Y.,  Ind.,  Ky.,  Falls  of  the  Ohio;  Leptcena  rhomboidalis, 
Wilckens,  Canada.  Also,  Pentamerella  arata  Con.,  N.Y.  and  the  West,  Atrypa  reticu- 
laris  Linn.,  A.  impressa  H.,  A.  aspera  H.  var.  occidentalis,  Amphigenia  elongataVan., 
Chonetes  hemisphericus  H.,  C.  lineatus  Van.,  Productella  navicella  H.  Meristella  nasuta 
Con.,  N.Y.  and  the  West. 

6.  Mollusks.     (a)  Lamellibranchs. — Fig.  871,  Paracyclas proavia  Goldf.  (elliptical!.), 
N.Y.,  Ohio,  Ind.     Fig.  872,  Conocardium  cuneus  Con.,   Ohio,  Ind. ;    Solenomya  vetusta 
Meek,  the  first  known  species  of  the  genus,  Ohio. 

(&)  Pteropods. —  Tentaculites  scalariformis  H.,  N.Y.,  Ohio,  Ind.,  Hyolithes  ligea  H. ; 
Conularia  elegantula  Meek. 

(c)  Gastropods  and  Cephalopods.  —  Fig.  873,  Platyceras  dumosum  Con.,  from  New 
York  and  Columbus,  Ohio.  A  dozen  species  of  Platyceras  have  been  described,  and  5  or  6 
or  more  of  each  Platystoma,  Euomphalus,  Loxonema,  Pleurotomaria,  Murchisonia, 


PALEOZOIC   TIME  —  DEVONIAN.  691 

Bellerophon.  Turbo  Shumardi  Vern.  is  a  fine  large  shell,  3£  inches  in  diameter, 
from  the  Falls  of  the  Ohio.  It  was  named  after  B.  F.  Shumard  of  St.  Louis.  It  is  well 
figured  by  Hall.  Among  Cephalopods,  30  species  of  Orthoceras  are  reported  by  Hall ; 
besides  these  there  are  12  of  Gomphoceras  (4  in  the  Schohariegrit),  as  many  of  Cyrtoceras 
and  Gyroceras  (4  Schoharie  grit),  9  of  Trochoceras,  all  from  the  Schoharie  grit;  1  Gonia- 
tites  (Fig.  874),  G.  mithrax  H.  (Tornoceras  mithrax  Hyatt,  and  referred  to  the  Corniferous 
with  some  doubt),  2  Discites.  Hyatt  states  that  most  of  the  species  of  Gomphoceras  have 
a  triangular  aperture  instead  of  lobed  like  that  on  page  561,  and  that  they  accordingly 
belong  to  his  genus  Acleistoceras.  The  species  of  Gastropods,  etc.,  are  described  and 
figured  in  Hall's  N.  Y.  Pal.,  vol.  v.  Gyroceras  undulatum  H.  is  a  type  of  Halloceras 
of  Hyatt ;  G.  Jason  H.  is  Rutoceras  Hyatt ;  Trochoceras  pandum  H.  is  Endoceras  Hyatt ; 
T.  clio  H.  is  Sphyradoceras  Hyatt;  T.  eugenium  H.  is  Ncedoceras  Hyatt. 

7.  Crustaceans.  —  The  most  common  Trilobites  are:  Fig.  875,  Dalmanites  selenurus, 
having  a  two-pointed  tail ;  and  Fig.  884,  Proetus  crassimarginatus  H.     There  are  also : 
Calymene  platys,  the  latest  American  species  of  the  genus,  and  one  of  the  largest  perfect 
specimens  being  4  inches  long,  and  an  imperfect  one  indicating  a  length  of  8  inches ;  over 
20  species  of  Dalmanites  (one  over  16  inches  long),  besides  the  Lower  Helderberg  species 
D.  pleuropteryx  ;  also,  of  Homalonotus  1  species,  of  Phacops  3,  Lichas  7,  Acidaspis  2  (Fig. 
879,  A.  callicera),  Proetus  over  15,  Cyphaspis  4,  and  the  new  genus  Phcethonides,  3  species. 

The  figures  of  Trilobites  on  page  587  represent  the  following  sub-genera,  as  recog- 
nized by  Hall :  Under  Dalmanites :  Odontocephalus  (D.  selenurus  Eaton) ;  Corycephalus 
(D.  regalis  H.);  Coronura  (D.  aspectans  Con.);  Cryphceus  (D.  Boothi  Green).  Under 
Lichas :  Hoplolichas ;  Ceratolichas.  For  figure  of  Palceocreusia,  see  Hall's  JV.  T.  Pal., 
vii.  pi.  36. 

8.  Vertebrates.  —  For  descriptions  and  figures  of  the  Fishes  mentioned  and  others, 
see  Newberry,    in    Ohio  Pal.  Rep.,  i.   and  ii.,  where  the  figures  of   the  large   species 
are   of  natural  size,  and  also  Ms  4to   Rep.  U.   S.   G.  S.,  1889 ;   also  papers  by  Cope, 
Claypole,  Whiteaves,  and  others.     From  the  Lower  Devonian  of  Cainpbelltown,  Canada, 
Whiteaves  has  described  fin-spines  of  Ctenacanthus  latispinosus  and  Homacanthus  gra- 
cilis.      The   Cephalaspis  Dawsoni  is  from  below  the  middle  of  the  Gaspe  sandstones, 
from  the  beds  affording  Prototaxites  Logani  and  other  plants.     That  the  beds  are  Lower 
Devonian  is  doubtful. 

At  Owl's  Head,  on  Lake  Memphremagog,  near  the  northern  borders  of  Vermont,  the 
coral-reef  rock  is  overlaid  by  mica  schist ;  and,  although  it  is  partially  metamorphic,  many 
of  the  specimens  of  fossils  are  tolerably  perfect.  Among  the  species,  Billings  has  recog- 
nized Syringopora  Hisingeri  B.,  Favosites  basalticus  Goldf.,  Diphyphyllum  stramineum  B., 
and  Zaphrentis  gigantea  Lesueur.  Besides  these,  according  to  Hitchcock,  Atrypa  reticu- 
laris  has  been  identified  by  Hall. 

Between  northern  Vermont  and  Cape  Gasp6  there  are  many  localities  of  Devonian 
fossils.  One  locality,  given  by  Logan,  is  on  the  Chaudiere  River,  where  occur,  besides 
Favosites  Gothlandicus  and  F.  basalticus,  the  species  Syringopora  Hisingeri,  Diphyphyllum 
arundinaceum  B.,  a  small  Productus  resembling  a  Corniferous  species,  a  Zaphrentis, 
Spirifer  duodenarius  H.,  S.  gregarius  Clapp,  8.  acuminatus  H.,  a  Cyrtina  like  C.  rostrata 
H.,  etc.  Other  localities  occur  at  Dudswell  and  on  Famine  River. 

Species  of  Brachiopods  range  as  follows :  From  the  Oriskany  to  the  Hamilton, 
Spirifer  Jimbriatus  Con.  (=  S.  Conradanus  S.  A.  Miller);  from  the  base  of  the  Lower  Hel- 
derberg or  beyond  to  the  Chemung,  Atrypa  reticularis  and  Stropheodonta  perplana,  but 
with  some  slight  characteristic  features  in  the  successive  periods  ;  from  the  Oriskany  to  the 
Chemung,  Stropheodonta  demissa  ;  from  the  Upper  Helderberg  to  the  Chemung,  Atrypa 
aspera ;  from  the  Schoharie  grit  to  the  Hamilton  or  Chemung,  Orthis  Vanuxemi,  Ortho- 
thetes  Chemungensis ;  common  in  the  Upper  Helderberg  and  Hamilton,  Spirifer  acumi- 
natus,  Meristella  nasuta. 


592  HISTORICAL   GEOLOGY. 

The  Devonian  of  California,  mentioned  on  page  680,  contains,  according  to  Schuchert,. 
Favosites  Canadensis,  Cyathophyllum  robustum,  Cladopora  labiosa,  Syringopora  Macluriif 
and  is  referred  by  him  with  a  query  to  the  Corniferous  ;  at  Gazelle,  in  Siskiyou  County,, 
occur  Diphyphyllum  fasciculum  and  Acervularia  pentagona ;  and  he  suggests  that  the 
beds  may  be  of  later  date  (1894). 

In  the  lower  part  of  the  Eureka  Devonian  limestone  (p.  589)  occurr  according  to- 
C.  D.  Walcott,  the  following  Corniferous  or  Lower  Devonian  species  of  New  York,  etc.:: 
Favosites  hemisphericus  Y.  &  S.,  Cyathophyllum  rugosum  Edw.  &  H.T  Orthis  impressa, 
Stropheodonta  perplana,  S.  punctulifera,  Chonetes  hemisphericus,  C.  mucronatus,  Spirifer 
raricosta,  S.  varicosus,  Atrypa  reticularis,  Nucleospira  concinna,  Meristella  nasuta,. 
Platyceras  carinatum,  P.  conicum,  P.  dentalium,  P.  nodosum,  Phacops  rcuna^  and  many 
others.  But  with  these  are  very  many  that  are  Middle  and  Upper  Devonian  in  New- 
York  and  elsewhere,  and  among  these  are  the  three  Hamilton  Tentaculites,  T.  atten- 
uatus,  T.  bellulus,  T.  gracilistriatus.  Besides,  some  New  York  Upper  Helderberg  species- 
are  found  in  the  upper  part  of  the  6000  feet  of  Devonian  limestone.  Again,  many  of  the 
species  of  the  lower  part  occur  also  in  the  upper  part,  showing  long  survival  of  individual- 
forms  ;  this  is  true  of  Orthothetes  Chemungensis,  of  4  species  of  Productus,  Chonetes- 
deflectus,  Stropheodonta  perplana,  2  of  Spirifer,  Hhynchonella  castanea  of  Meek  (a  Mac- 
kenzie River  species),  a  Paracyclas,  Styliolina  fissurella.  Orthis  McFarl&ni  Meek  is  a. 
second  Mackenzie  River  species ;  and  as  the  two  are  Lower  Devonian  in  Nevada,  they 
may  be  so  at  the  arctic  localities.  Many  of  the  species  are  represented  in  the  Devoniani 
of  Iowa,  or  the  Continental  Interior,  where  the  waters  were  purer  and  probably  deeper 
than  in  the  New  York  Bay,  and  therefore  more  like  those  of  the  Eureka  district. 

Of  the  Eureka  Devonian  species  that  are  found  only  in  the  upper  division,  the  follow- 
ing are  confined  to  the  Lower  Devonian  in  New  York :  Syringopora  Hisingeri,  Cyatho- 
phyllum corniculum,  and  Chonetes  mucronatus ;  and  the  following  are  among  those  that 
are  Middle  or  Upper  Devonian  in  New  York  or  Iowa:  Orbiculoidea  minuta  (Hamilton), 
Orthis  Tulliensis  (Ham.),  Productus  lacrymosus  (Chemung),  P.  speciosus  (Ch.),  Spirifer 
disjunctus  (Ch.),  Athyris  angelica  (Ch.),  Rhynchonella  duplicata  (Ch.),  H.  Laura  (Ham.), 
It.  sinuata  (Ch.),  Sellerophon  mvera  (Ch.).  The  preceding  conclusions  appear  to  be  well 
sustained,  unless  it  may  be  that  there  are  unseen  faults  in  the  limestone.  See,  further,. 
Walcott,  Pal  Eureka,  U.  8.  G.  S.,  4to,  vol.  viii.,  1884,  where  144  Devonian  species  are 
described ;  and  also  Arnold  Hague,  Hep.,  vol.  xx.,  U.  S.  G.  8. 

3.   HAMILTON  PERIOD,  OR  MIDDLE  DEVONIAN. 
ROCKS  — KINDS,  SUBDIVISIONS,  AND  DISTRIBUTION. 

The  Hamilton  group  was  so  named  from  Hamilton,  in  Madison  County, 
N.Y.  The  beds  have  a  wide  range,  like  the  Corniferous  limestone.  They 
extend  from  eastern  New  York  (Schoharie  County)  westward  to  Iowa;  but  in 
New  York  and  Pennsylvania  they  are  mainly  shales  and  sandstones,  of  shallow 
water  origin,  and  wholly  calcareous  only  in  the  Central  Interior  region. 
Moreover,  they  have  great  thickness  to  the  eastward,  1500  feet,  but  thin 
down  rapidly  to  the  westward,  being  only  300  to  1100  feet  thick  near  Lake 
Erie,  thinning  down  to  20  to  50  feet.  They  border  Lake  Erie  in  Ontario ;  pass 
by  the  south  end  of  Lake  Huron  into  Michigan,  where  they  are  limestone, 
and  10  to  120  feet  thick.  They  appear  also  in  Ohio,  as  25  feet  of  impure 
bluish  limestone ;  in  Indiana,  where  at  the  Falls  of  the  Ohio,  above  Louisville, 
they  are  20  feet  thick,  and  include  the  hydraulic  and  overlying  beds  of  the 
limestone  formation  of  the  place.  They  occur  also  in  Kentucky ;  Illinois, 


PALEOZOIC   TIME  —DEVONIAN.  598 

at  Rock  Island,  etc.;  Wisconsin,  north  of  Milwaukee;  in  Iowa,  near 
Independence ;  on  the  Mississippi,  shale  (Marcellus)  overlaid  by  limestone  ; 
and  in  Missouri.  The  greatest  thickness  is  along  the  Appalachian  region, 
where  the  beds  are  almost  wholly  fragmental;  and  within  these  limits  in 
Monroe  County,  eastern  Pennsylvania,  the  group  is  2000  to  5000  feet  thick. 

The  Hamilton  group  of  New  York  has  as  its  lower  member,  the  Marcellus 
shale,  a  formation  of  soft,  black  shale,  except  near  the  bottom,  where  occurs 
a  thin  limestone  stratum  called  the  Ooniatite  limestone.  The  shale  is 
bituminous,  and  much  unavailing  search  for  coal  has  hence  been  made  in  it. 
Hall  states  that  in  many  places  it  contains  so  much  bitumen  as  to  give  out 
flame  when  thrown  into  a  fire  of  hot  coals.  Its  fossils  are  few  in  species, 
and  mostly  small,  excepting  the  Goniatites. 

Above  the  Marcellus  come  the  true  Hamilton  beds  —  chiefly  shaly  sand- 
stones with  some  fine  shales  and  thin  limestone  layers ;  and  at  top,  in  many 
places,  the  Tully  limestone,  10  to  20  feet  thick,which  is,  by  some,  made  the  base 
of  the  Upper  Devonian.  This  limestone  is  sometimes  referred  to  as  the 
Cuboides  zone,  in  reference  to  a  common  fossil,  Rhynchonella  cuboides. 

In  eastern  New  York,  in  Ulster,  Green  and  Albany  counties,  the  Hamilton 
affords  "the  North  River  flagstone,"  affording  excellent  flags  and  pavements, 
used  much  in  New  York  and  the  adjoining  states.  The  thicker  layers  are 
called  bluestone,  from  the  bluish  gray  color.  The  bluestone  is  easily  worked 
by  machine-planing  for  use  in  the  trimmings  of  buildings,  and  is  convenient 
for  the  purpose  if  the  stone  can  be  selected  that  will  not  drip  iron  stains  down 
the  front  below  a  course  of  it.  The  flagstone  contains  an  occasional,  slender 
worm-boring,  and  coaly  fragments,  and  is  often  ripple-marked,  like  other 
layers  of  the  Hamilton.  Moreover,  the  strata  are  frequently  intersected  by 
joints  of  great  extent  and  regularity.  The  scene  in  Fig.  121,  page  112,  is 
from  the  Hamilton  near  Cayuga  Lake. 

In  eastern  Canada,  at  Gaspe  and  Baie  des  Chaleurs,  a  middle  portion  of 
the  7036  feet  of  Devonian  sandstones  is  referred  to  the  Hamilton  or  Middle 
Devonian ;  and  the  next  above  to  the  Upper  Devonian.  The  Little  River 
group  of  Nova  Scotia,  and  Cordaites  shales  and  flags  of  St.  John  County, 
New  Brunswick,  are  referred  to  the  Hamilton  by  Dawson. 

West  of  the  Mississippi,  in  the  Eureka  district,  Nevada,  the  8000  feet  of 
Devonian  limestone  and  shale  include  the  Hamilton  group;  but  it  has  not 
been  found  possible  to  separate  the  Hamilton  portion.  Hamilton  beds  are 
also  found  in  the  valley  of  the  Mackenzie  River,  between  Clear  Water  River 
and  the  Arctic  Ocean,  some  of  the  species  of  fossils  being  identical  with 
those  of  the  United  States  and  Canada  (Meek). 

Interior  Continental  Region. — The  Hamilton  beds  of  New  York  are  separated 
into  two  parts  by  a  thin  layer  of  Encrinal  limestone.  The  annexed  section  (by  Hall)  is 
from  the  borders  of  Lake  Erie.  The  Hamilton  beds,  10  6,  include  (1)  blue  shale,  (2)  En- 
crinal limestone,  (3)  Upper  or  Moscow  shale  ;  the  Tully  limestone  is  wanting.  Above  lie 
(10  c)  the  Genesee  slate,  and  (11)  a  following  part  of  the  Portage  group,  both  of  the  Upper 
Devonian.  A  section  near  Canandaigua  Lake,  in  Ontario  County,  N.Y.,  includes,  accord- 
DANA'S  MANUAL  —  33 


594  HISTORICAL   GEOLOGY. 

ing  to  J.  M.  Clarke,  (1)  Marcellus  shale,  100' ;  (2)  a  thin  stratum  of  limestone  of  coral-reef 
character,  at  the  base  of  the  Hamilton  beds  ;  (3)  the  lower  shales  of  the  Hamilton,  140' ; 
(4)  the  Encrinal  Band  ;  (5)  the  Upper  shales,  250'.  In  Chautauqua  County,  a  boring  gave 

50'  Marcellus  shale  and  395'  Hamilton  (G.  D.  Harris, 
1891).     To  the  eastward,  the  beds  are  coarser  and 
more  arenaceous.     The  Tully  limestone  thins  out 
in  the  eastern  part  of  Ontario  County,  and  is  the 
most  southern  limestone  in  New  York  State.     It 
is  quarried  and  burnt  for  lime  in  the  village  of 
_      Tully,  Onondaga  County,  where  it  is  12'  thick. 
Section  of  Hamilton  beds,  Lake  Erie.    Hall.      The  flagging-stone   of  the    Hamilton  is  quarried 

near  Kingston,  Saugerties,  Coxsackie,  and  else- 
where on  the  Hudson.  In  Perry  County,  central  Pennsylvania,  the  Marcellus  is  200' 
thick,  and  the  Hamilton,  900'  or  more  ;  they  consist  of  shales  and  sandstones,  and  include 
the  Montebello  sandstone.  At  the  Falls  of  the  Ohio,  the  Hamilton  is  represented  by  a 
magnesian  limestone,  more  or  less  shaly.  On  the  west  side  of  the  Mississippi  River,  in 
Iowa,  outcrops  south  of  Davenport  consist  of  about  50'  of  shale  with  some  crinoidal 
limestone.  In  Missouri,  Swallow  reported  the  occurrence  of  Hamilton  shales,  45'  thick, 
near  Ashley,  in  Pike  County. 

In  eastern  Pennsylvania,  Monroe  County,  where  the  thickness  of  the  beds  of  the  Ham- 
ton  period  is  1750'  to  5000',  that  of  the  Marcellus  shale  is  200'  to  800'  or  more.  The  shale 
is  black  to  gray  in  color,  and  the  darker  kinds  are  very  carbonaceous,  or  even  coaly  at 
times.  Tully  limestone  is  absent.  The  high  cliffs  on  the  Delaware,  in  Pike  County,  from 
Port  Jervis  southward,  are  Hamilton.  North-northwest  of  Monroe  County,  in  Columbia 
County,  Penn.,  the  whole  thickness  is  2200'  to  2500' ;  but  farther  south,  near  the  south 
border  of  Northumberland  County,  Penn.,  a  highly  disturbed  region,  the  total  thickness, 
for  some  reason,  is  stated  to  be  only  600'.  Prosser  made  a  section  across  Monroe  County, 
along  the  D.,  L.  and  Western  R.R.,  and  found  the  Marcellus  shale  800'  thick,  and  the 
Hamilton  overlying  it,  1400',  the  latter  being  proved  by  the  fossils  to  include  the  Hamilton, 
Tully,  and  Genesee  beds  of  I.  C.  White's  Report. 

In  the  Eastern-border  region,  at  Gaspe,  the  6000'  of  sandstones,  above  the  1100' 
referred  to  the  Corniferous  period,  are  believed  to  be  for  the  most  part  of  Hamilton  age. 
St.  John,  in  New  Brunswick,  is  a  noted  locality  of  fossil  plants  of  this  era.  In  that 
region  there  are  (1)  below,  of  the  Middle  Devonian  series,  the  Dadoxylon  sandstone 
resting  on  the  Bloomsbury  conglomerate,  and  overlaid  by  the  Cordaites  shales  ;  (2)  above 
the  Mispec  conglomerate  and  slate  ;  and  (3),  of  the  Upper  Devonian,  the  Perry  sand- 
stones, with  remains  of  plants.  (Dawson.) 

The  Devonian  is  well  developed  in  the  Mackenzie  River  district,  British  America,  and 
southward  in  the  vicinity  of  lakes  Manitoba  and  Winnipegosis.  In  the  Mackenzie  River 
district  the  section  shows  (1)  at  the  base  200'  of  grayish  limestone,  interstratified  with 
dolomytes,  the  lower  part  of  which  may  be  older  than  the  Devonian  ;  above  this,  (2)  about 
500'  of  greenish  and  bluish  shales  alternating  with  limestones,  followed  by  (3)  about  300' 
of  limestones.  (McConnell.) 

Whiteaves  has  described  a  rich  fauna,  mainly  from  the  upper  part  of  the  second 
division.  Among  the  species,  22  are  also  found  in  the  Hamilton  formation  of  Ontario 
and  New  York  ;  10  are  also  found  in  Iowa,  there  referred  to  Chemung ;  and  7  are  regarded 
as  characteristic  Chemung  fossils  in  New  York  and  Pennsylvania ;  29  of  the  species  are 
either  identical  (19),  or  closely  allied  with  European  Devonian  species.  Mr.  Whiteaves 
considers  the  fauna  to  belong  to  the  "  Cuboides  zone"  of  Europe,  of  which  the  Tully 
limestone  of  New  York  is  by  Williams  regarded  as  an  equivalent. 

The  Manitoba  section  consists  of  (1)  a  few  feet  of  red  shales  resting  upon  Silurian 
rocks,  followed  by  (2)  200'  of  dolomytes,  and  then  by  (3)  60'-75'  of  calcareous  shales, 
above  which  are  (4)  the  fossiliferous  limestones  containing  the  "  Cuboides  fauna."  The 


PALEOZOIC   TIME DEVONIAN. 


596 


dolomytes  are  referred  to  the  Middle  Devonian,  the  Stringocephalus  zone  of  Europe,  con- 
taining characteristic  specimens  of  S.  Burtini,  one  specimen  measuring  7  by  5  inches  in 
diameter. 

LIFE. 

PLANTS.  —  In  the  beds  of  the  Hamilton  period,  the  evidences  of  verdure 
over  the  land  are  abundant.  The  remains  show  that  there  were  trees,  as 
well  as  smaller  plants ;  that  there  were  forests  of  moderate  growth,  and 
great  jungles  over  wide-spread  marshes.  The  plants  included  Lycopods,  Ferns, 
and  Equiseta,  the  three  orders  of  Acrogens,  or  higher  Crytogams ;  and  also 
Gymnosperms,  among  Phaenogams. 

1.  Lycopods.  —  The  Lycopods  generally   have   scars  over  the   exterior, 
much  like  those  of  a  branch  of  spruce  after  the  leaves  have  been  removed. 
A  Hamilton  specimen  of  the  Lepidodendron  primcevum  is  represented  in 
Fig.  894,  and  of  another  species  in  Fig.  895.     L.  Gaspianum  (see  Fig.  855) 
has  been  found  in  the  Genesee  slate  of  New  York  and  Pennsylvania. 

2.  Ferns. — Many  species  of  ferns  have  been  described  from  beds  of  the 
Hamilton  period,  the  most  of  them  from  those  of  St.  John,  New  Brunswick. 
One   species,  a  Neuropteris,  is  represented  in  Fig.  897;  part  of  a  frond  of 
another,  an  Archceopteris,  in  Fig.  898,  and  a  single  leaflet,  illustrating  the 
divergent  nervures  of  this  genus,  in  Fig.  899.     Large  trunks  of  tree-ferns 
have  been  found  in  the  Hamilton  beds  of  New  York  and  Ohio,  showing  that 


894-899. 


894. 


895. 


896. 


ACROGENS.  —  Fig.  894,  Lepidodendron  primsevum ;  895,  Sigillaria  Halli ;  896,  Cordaites  Kobbii ;    897,  Neuropteris 
polymorpha ;  898,  899,  Archaeopteris  Jacksoni.     Fig.  894,  Lesquereux ;  895,  Meek ;  896-899,  Dawson. 

there  was  beauty  of  foliage  in  the  forests,  if  not  of  flowers.  One  of  them, 
Psaronius  Erianus  Dawson  (1870,  1871)  had  a  trunk  three  to  four  feet  in 
diameter,  and  was  therefore  a  tree  of  large  size. 


596  HISTORICAL   GEOLOGY. 

3.  Equiseta  or  Horse-tails.  —  Calamites  (named  from  calamus,  a  reed,  in 
allusion  to  their  reed-like  or  rush-like  aspect)  are  ancient  Equiseta.  Fig. 
900  represents  a  portion  of  a  stem  (in  horizontal  position)  flattened  out  by 


900.  901. 


Fig.  900,  Archseocalamites  radiatus  ;  901,  Asterophyllites  latifolius.     Dawson. 

pressure.  It  shows  that  the  Devonian  species  of  the  tribe  exceeded  much  in 
size  the  modern  species ;  as  in  recent  kinds,  the  stems  were  jointed  (ab).  A 
plant  of  the  same  tribe,  called  Asteropliyllites  (because  of  the  arrangement  of 
the  leaves  in  stars),  is  represented  in  Fig.  901. 

4.  Gymnosperms.  —  Gymnosperms    were   represented  by  species   of   the 
Yew   family  (Taxineae),  and   by   leaves  of   plants  of   the  tribe  of  Cycads. 
Trunks  a  foot  in  diameter,  of  the  former,  occur   in  the  black   shale   of  the 
Hamilton,  and  others  as  large,  or  larger,  in  the  New  Brunswick  beds.     Most 
of  the  latter  are  referred   by  Dawson  to  the  genus  Dadoxylon.     To  the  Cycad 
family  belongs  the  Cordaites  Robbii,  a  leaf  of  which,  from  a  cluster  figured 
by  Dawson,  is  represented  in  Fig.  896.     It  is  questioned  whether  leaves  like 
those  of  Archwopteris  may  not  be  from  a  related  Cycadean,  as  one  genus  of 
modern  Cycads,  Strangeria,  has  fern-like  leaves  (Williamson).     Fossil  nuts 
were  found  with  the  specimen  of   C.  Robbii,  which  "may  have  belonged  to 
it"  (Dawson). 

5.  Sporangites. —  Spore-cases  and  spores  are  abundant  in  the  black  Mar- 
cellus  shale  of  New  York  and  Pennsylvania,  and  are  a  prominent  source 
of  its  bituminous  character.     They  are  usually  minute  black  shining  spots  in 
the  shale. 

ANIMALS. — The  animal  remains  of  the  Marcellus  are  comparatively 
few,  and,  excepting  the  Cephalopods,  generally  small.  Their  small  number 
corresponds  with  the  fact  that  the  rock  is  a  fine  shale.  In  the  Hamilton 
beds,  which  are  coarser,  and  often  resemble  a  consolidated  mud-bed,  fossils 
are  much  more  numerous;  but  Lamellibranchs  and  Brachiopods  are  most 
abundant,  as  is  usual  in  impure  waters. 

1.  Spongiozoans.  —  A  Middle  Devonian  species  of  Splicer  ospongia,  first 
described  by  Phillips  from  British  specimens,  is  represented  in  Figs.  902  a,  b, 


PALEOZOIC   TIME  —  DEVONIAN. 


597 


from  Manitoba  specimens  described  by  Whiteaves  ;  the  latter  figure  shows 
the  natural  outer  surface,  consisting  of  hexagonal  plates,  and  the  former, 
the  interior ;  Fig.  902  c,  is  from  a  portion  of  the  exterior  enlarged,  and  902  d 


902-902  c. 


902  c. 


902. 


903. 


SPONGIOZOAN.  —  Fig.  902,  a,  Sphaerospongia  tesselata  :  6,  enlarged  view  of  exterior  hexagonal  plates  ;  c,  enlarged 

view  of  spicules.     Whiteaves,  '92. 

represents  the  cruciform  spicules.  The  genus  is  put  in  the  same  group  with 
Receptaculites,  by  Banff,  who  doubts,  as  in  the  case  of  that  genus,  the  sup- 
posed relation  to  Sponges,  and  states  that  the  spicules  were  originally  calca- 
reous. The  rock  is  dolomyte. 

2.  Polyp-corals.  —  Corals  are  found  chiefly  in  con- 
nection with  the  few  beds  of  limestone ;  and  near 
Canandaigua,  N.Y.,    and     to    the    westward,   the 
Hamilton   contains   large    numbers    in    coral-reef 
style.     Fig.  903  represents  a  common  species  of 
Heliophyllum ;  and  among  the  other  genera  there 
are   CyathopJtyllum,  Cystiphyllum,  Zaphrentis,  Favo- 
sites,  and  Michelinia. 

3.  Crinoids.  — Crinoids  occur  sparingly,  in  New 

York,  but   more  abundantly  at   the  Falls  of   the     HeiiophyUum^Ham.    Edw.and 

Ohio.     They  include  species  of  Platycrinus,  Actin- 

ocrinus,  Cyathocrinus,  Rlwdocrinus ;  also  Nudeocrinus,  Pentremites,  etc. 

4.  Molluscoids. — Brachiopods   continue    to    be   common    fossils.     Figs. 


598 


HISTORICAL    GEOLOGY. 


904  to  911  represent  the  most  common  kinds.     The  broad-winged  species, 
Fig.  907,  Spirifer  pennatus,  was  one  of  the  most  abundant. 


904-911 


904 


906 


BEACHIOPODS.  —  Fig.  904,  A  try  pa  uspera;  905,  A.  reticularis ;  906,  Tropidoleptus  carinatus;  907,  Spirifer 
pennatus  ;  908,  Athyris  spiriferoides  ;  909,  Amboccelia  umbonata  ;  910,  Chonetes  setigerus  ;  911,  Product- 
ella  subalata.  Figs.  904,  906-908,  Meek ;  905,  909-911,  Hall. 

5.  Mollusks.  —  In  the  shaly  sandstones  of  this  period  Lamellibranchs 
abound.  21  species  have  been  described  by  Hall  from  the  Marcellus  beds, 
and  174  from  the  Hamilton,  only  one  being  common  to  the  two.  But  in 
Ohio  and  farther  west,  where  the  beds  are  calcareous,  they  are  few  in  num- 
ber. Only  10  New  York  species  occur  at  the  Falls  of  the  Ohio.  The  follow- 
ing figures,  912-916,  show  some  of  the  characteristic  species.  The  Gastro- 


916. 


91 2-91 fi 


CONCHIFEES.  —  Fig.  912,  Orthonota  undulata  (xf);  913,  Pterinea  flabella(x|);  914,  Grammysia  bisulcata ;  915, 
Microdon  (Cypricardella)  bellistriatus ;  916,  Styliolina  flssurella.  Fig.  912,  916,  Hall ;  913,  915,  Conrad ;  914, 
deVerneuil. 

pods  were  mostly  of  the  same  genera  as  in  the  earlier  Devonian :  Platyceras. 
(many   species),   Platystoma,    Trochonema,   Pleurotomaria    (many),   Euom- 


PALEOZOIC   TIME  —  DEVONIAN. 


599 


917: 


phalus,  Bellerophon  (many  species),  Murchisonia  (but  one),  Loxonema  (many), 
with  also  the  Devonian  and  Carboniferous  genus  Macrocheilus.  Pteropods 
were  still  represented  by  Tentaculites,  Hyolithes,  and  Conularia,  and  also  by 
species  of  Styliolina  (Fig.  916),  Coleolus,  etc.  Styliolina  is  like  Tentaculites, 
but  has  a  smooth  shell. 

Under  Cephalopods,  the  old  genus,  Orthoceras,  had  29  described  species 
in  1880  (to  30  in  the  Corniferous);  with  these  were  species  of  Gomphoceras, 
Cyrtoceras,  and  Gyroceras.  The  Nau- 
tiloid,  Nepliriticeras  maximum  occurs 
over  a  foot  in  diameter.  The  genus 
Goniatites,  first  known  from  the  Cor- 
niferous group,  has  a  number  of  spe- 
cies ;  G.  Vanuxemi  (Fig.  917)  is  one 
of  the  earliest,  being  from  the  Mar- 
cellus  shale ;  it  has  only  one  flexure 
in  the  septa,  as  shown  in  Fig.  917  a, 
a  mark  of  its  antiquity;  and  it  has 
been  made,  on  this  account,  by  Hyatt, 
the  type  of  the  new  genus  Agonia- 
tites.  The  largest  specimens  are  a 
foot  or  more  in  diameter.  A  straight 
form  of  Goniatites,  Bactrites  davus 
H.,  has  been  found  in  the  New  York 
Marcellus  shale. 

6.  Crustaceans.  — The  most  characteristic  species  of  Trilobite,  Phacops  rana 
of  Green  (  =  P.  bufo),  is  represented  in  Fig.  918;  its  maximum  length  is 
eight  inches.  The  genus  Dalmanites,  which  had  nearly  25  Corniferous 
species,  has  five  described  from  the  Hamilton;  the  pygi- 
dium  of  D.  Boothi  Green  is  represented  on  page  587, 
and  that  of  the  variety  calliteles,  in  Fig.  919.  Other  genera 
are  Homalonotus  (which  has  a  species  15  inches  long), 
Proetus,  and  Acidaspis.  Fig.  880  (page  587)  is  the  pygi- 
dium  of  A.  Romingeri.  There  is  also  a  species  of  the 
European  genus  Bronteus,.B.  Tullius  H.,  found  in  the  Tully 
limestone.  Out  of  all  the  genera  of  Trilobites  existing 
during  the  Hamilton  and  earlier  geological  time,  only 
Phacops  and  Cyphaspis  have  species  reported  from  the  later 
Devonian.  Others  no  doubt  existed ;  but  still  the  decline 
of  what  was  once  the  leading  life  of  the  seas  is  strongly 
manifested.  The  dash  for  ornamentation  in  the  early  and 
middle  Devonian  was  a  mark  of  luxuriant,  rather  than 
natural  progress,  and  the  same  appears  in  the  size  of  many 
of  the  species. 

Phyllopods,  of  the   Ceratiocarid   type,  are   of   several  kinds.     Fig.  920 
represents  an  Echinocaris,  one  specimen  of  which,  figured  by  Hall,  from 


CEPHALOPOD.  —  Figs.  917,  a,  Goniatites  Vanuxemi. 
Meek. 


918-919. 


Fig.  918,  Phacops  ra-'« 
na;  919,  pygidium 
of  Dalmanites  cal- 
liteles (x|).   Meek. 


600 


HISTORICAL   GEOLOGY. 


920. 


near  Canandaigua  Lake,  is  eight  inches  long.      Another  kind,   Mesothyra 
Neptuni  H.,  differed  little  from  the  Portage    species,  M.   Oceani,   figured 

on  page  615,  and  was  probably  nearly 
a  foot  long,  independent  of  the  tail 
spines,  which  add  five  and  a  half 
inches. 

There  were  also  Ostracoid  Crusta- 
ceans of  several  genera,  and  among 
them  the  oldest  known  of  Estherise 
—  E.  pulex  of  Clarke.  The  Barnacle 
tribe  of  Crustaceans  also  had  its 
species.  Fig.  922  rep- 
resents a  true  sessile 
barnacle  of  the  Hamil- 
ton, Protobalanus  Ham- 
iltonensis  Whitfield, 
and  Fig.  921  two  plates 
of  the  pedunculate  Bar- 
nacles of  the  Lepas 
family,  named  Turri- 
lepas  Devonicus  by 
Clarke. 


922. 


Fig.  920,  Echinocaris  punctata;  921,  921  a, 
Turrilepas  Devonicus.  Fig.  920,  Beecher ; 
921,  Clarke. 


Fig.  922,  Protobala- 
nus Hamiltonensis. 
Whitfield. 


7.  Insects.  —  Remains  of  Insects  have  been  found  at  St.  John,  New  Bruns- 
wick. They  are  related  to  the  Ephemerve  or  Mayflies;  and  one  of  these 
is  represented  in  Fig.  923 — the  Platephemera  antiqua  of  Scudder —  species 
whose  larves  live  in  the  water,  and  which  frequent  moist  places,  and  there- 
fore stood  a  good  chance  of  becoming  preserved  as  fossils.  It  was  a  gigantic 
species,  measuring  five  inches  in  spread  of  wings. 

923. 


Fig.  923,  Platephemera  antiqua;  924,  Xehoiieura  antiquorum.    Scudder. 

Several  other  species  of  Insects  have  been  described  from  the  same 
locality.  One  of  them,  the  Xenoneura  antiquorum  of  Scudder  (Fig.  924), 
while  related  to  the  Ephemerids,  under  the  Neuropters,  has  some  characters 
of  the  Orthopters,  one  of  which  is  the  possession,  according  to  Scudder,  of 
what  appears  to  be  a  stridulating  organ  on  the  surface  of  the  wing  near  its 
base  (see  the  figure),  an  organ  for  making  their  shrill  sounds  by  friction. 


PALEOZOIC   TIME  —  DEVONIAN.  601 

Dawson  thereupon  observes  that  "  the  trill  and  hum  of  insect  life  must  have 
enlivened  the  solitudes  of  the  strange  old  Devonian  forests."  Insects  appear 
to  have  been  the  only  winged  life  of  the  Devonian  and  Carboniferous  ages. 

8.  Vertebrates.  — Remains  of  Fishes  occur  sparingly  in  the  Hamilton  beds, 
•while  abundant  in  the  overlying  Genesee  and  Portage  beds.  Those  observed 
are  the  plates  or  fragments  of  jaws  of  Placoderms,  or  teeth  or^fin-spines  of 
:Selachians.  One  of  the  large  fin-spines,  from  the  Hamilton  beds  of  Yates 
County,  N.Y.,  called  Ctenacanthus  Wrighti  by  Newberry,  is  nine  inches  long 
.and  an  inch  and  a  half  in  diameter  at  base. 

Characteristic  /Species. 

PLANTS.  —  The  seaweed,  Spirophyton,  occurs  in  the  Hamilton  and  through  the  later 
Devonian.  Fig.  894,  of  Lepidodendron  primcevum  Rogers,  shows  only  the  inner  surface  of 
the  bark,  and  not  the  true  surface  scars.  Fig.  896  is  one  of  a  group  of  leaves  of  Cordaites 
Hobbii,  figured  by  Dawson  ;  and  Figs.  897,  898,  from  Dawson,  are  portions  only  of  his 
iigures.  For  J.  M.  Clarke's  papers  on  Sporangites,  see  Am.  Jour.  Sc.,  xxix.,  1885. 

ANIMALS.  1.  Spongiozoans.  —  Sphcerospongia  tesselata  (Fig.  902)  is  associated  with 
Terebratula  (Eunella)  Sullivanti  Hall,  of  the  Corniferous,  Spirifer  fimbriatus  Con.,  Pen- 
Jta.nerus  comis,  Atrypa  reticularis,  Nucula  lirata  Hall,  of  the  Hamilton  shales,  Para- 
'Cyclas  elliptica  Hall,  of  the  Corniferous  and  Hamilton,  Goniophora  perangulata  Hall,  of 
the  Schoharie  grit,  etc. ;  also,  the  following  European  species,  not  known  from  the  United 
.States,  Murchisonia  turbinata,  Euomphalus  annulatus,  String ocephalus  Burtini,  Loxonema 
priscum,  Macrochilina  subcostata,  etc.  The  String  ocephalus  is  characteristic  of  the 
" Stringocephalus  zone"  of  the  Middle  Devonian  of  Europe.  The  Devonian  fossils  of 
.Manitoba,  according  to  Whiteaves,  have  close  relation  to  those  of  Europe,  while  many 
•differ  in  species  from  those  of  the  United  States. 

2.  Actinozoans.  —  Fig.  903,  Heliophyllum  Halli  E.  &  H.,  N.Y.,  H.  obconicum  H., 
H.  confluens  H.,  Cyathophyllum  robustum  H.,  C.  nanum  H.,  C.  conatum  H.  ;  Zaphrentis 
Halli  E.  &  H.,  Z.  simplex  H.,  Cystiphyllum  varians  H.,   C.  Americanum  E.  &  H.,   C. 
conifollis  H.,  Amplexus  Hamiltonice  H.;  Michelinia  stylopora  Eaton,  Favosites  placenta 
Rominger,  F.  arbuscula  H.,  F.  Hamiltonice,  F.  Argus,  all  from  a  "coral-reef"  area  of 
the  N.Y.  Lower  Hamilton,  near  Canandaigua,  N.Y.  (Clarke),  and  nearly  equally  abundant 
to  the  westward  in  New  York  and  Ontario. 

3.  Echinoderms. — The  forms,  described  under  the  generic  name,  Heteroschisma,  by 
Wachsmuth,  from  Iowa,  show  a  relation  between  Cadaster  and  Pentremites  (III.  G.  Rep., 
vii.,  1883). 

4.  Molluscoids.  — Large  numbers  of  Bryozoans  are  described  in  Hall's  vol.  vi.,  of  the 
N.  Y.  Geological  Survey. 

Brachiopods.  —  Tig.  904,  Atrypa  aspera  Schloth,  also  European;  905,  A.  reticularis, 
larger  than  the  same  in  the  Corniferous,  and  fuller,  sometimes  nearly  2  inches  broad ; 
906,  Tropidoleptus  carinatus  H.,  New  York,  Illinois,  Iowa,  Europe  ;  907,  Spirifer  mucro- 
natus  Con.,  very  common  ;  908,  Athyris  spiriferoides  Eaton ;  909,  Amboccelia  umbonata, 
N.Y.  and  the  West ;  910,  Chonetes  setigerus  H.,  in  the  Marcellus  and  Genesee  shales,  and 
also  the  Chemung  ;  911,  Productella  subalata  H.,  Rock  Island,  HI. ;  Spirifer  granuliferus 
H.,  a  large  species,  having  a  granulated  surface. 

The  Ehynchonella  cuboides  is  characteristic  of  the  Tully  limestone ;  and  as  beds 
containing  this  species  and  others  associated  with  it  in  England  and  Europe  are  referred 
to  the  base  of  the  Upper  Devonian,  the  "Frasnian  stage,"  the  limestone,  according  to 
H.  S.  Williams,  ought  to  be  arranged  with  the  Upper  Devonian  in  New  York,  etc.  He 


602  HISTORICAL   GEOLOGY. 

observes  that  the  facts  from  the  Devonian  of  Manitoba  and  Mackenzie  rivers  described  by 
Whiteaves  confirm  this  view. 

5.  Mollusks. —  (a)  Lamellibranchs. — Fig.  912,  Orthonota  undulata  Con. ;  913,  Pterinea 
flabella  Con.;  914,  Grammysia  bisulcata  Con.  (Hamiltonensis  of  Verneuil),  also  Euro- 
pean, in  the  Eifel ;   915,  Microdon  bellistriatus  Con.     Of  the  genera  of  Lamellibranchs 
represented,  Grammysia  has  15  species  (all  in  the  Hamilton),  Modiomorpha  9  (all  Ham., 
1  also  Marc.),  Amcidopecten  15,  one,  A.  princeps,  occurring  in  New  York,  Ontario,  Ken- 
tucky, and  Indiana.     Nucula  9  (all  Ham.),  Leda  4  (all  Ham.),  Paracyclas  (Lucina)  4, 
Schizodus  3,  Solemya  1,  Orthonota  4  (all  Ham.),  Lunulicardium  5  (all  Marc.,  and  2  con- 
tinuing into  the  Hamilton). 

(6)  Gastropods.  —  Of  the  10  species  of  Platyceras,  P.  conicum,  P.  erectum,  P.  cari- 
natum,  P.  thetis,  P.  symmetricum  and  P.  rectum  come  up  from  the  Corniferous.  There 
are  a  dozen  species  of  Bellerophon,  several  of  them  like  B.  patulus,  large  and  beauti- 
ful, much  exceeding,  in  both  respects,  any  of  the  Silurian  species. 

(c)  Pteropods  and  Cephalopods. — For  figures  and  descriptions  of  many  species,  see 
Hall,  vol.  v.  ;  also  publications  of  Meek  and  Worthen,  Whitfield,  Beecher,  Billings,  and 
others.  Among  the  species  are  Orthoceras  crotalum  H.  (Spyroceras  of  Hyatt);  Gom- 
phoceras  oviforme  H.  (Acleistoceras  Hyatt)  ;  Gyroceras  transversum  H.  (Hutoceras  Hyatt)  ; 
Nautilus  buccinum  H.  (Nephriticeras  Hyatt,  a  type  having  many  Hamilton  species)  ; 
Goniatites  (Discites)  Marcellensis  Van.  (Centroceras  Hyatt)  ;  Goniatites  discoideus  H. 
(Parodiceras  Hyatt). 

6.  Crustaceans. — For  figures  of  the  Hamilton  (and  other  Devonian)  species  of  these 
tribes,  see  Hall,  N.  Y.  Pal.,  vol.  vii. ;  Beecher,  Hep.  Geol.  Pa.,  vol.  PPP,   1884  ;  Packard, 
Monograph  on  N.  A.  Phyllop.,  1883;  Whitfield,  Am.  Jour.   So.,  xix.,  1880;   and  J.  M. 
Clarke,  Am.  Jour.  Sc.,  xxiii.%  1882;  and  i7>.,  xxiv.,  1882  (on  Turrilepas).     Dithyrocaris 
Belli  Woodw.  (Geol.  Mag.,  1871)  is  from  Gaspe". 

Some  of  the  characteristic  Marcellus  fossils  are  :  Productella  truncata  H.,  Orbiculoidea 
minuta  H.,  Leiorhynchus  limitare  H.,  Chonetes  mucronatus  H.,  Leiopteria  Icevis  H.,  Pleu- 
rotomaria  virgulata  H.,  Styliolina  fissurella  H.,  Orthoceras  subulatum  H. 

The  Iowa  Hamilton  has  afforded  species  of  Megistocrinus,  Taxocrinus.  Synbatho- 
crinus,  Pentremites ;  Orthis  suborbicularis  H.,  O.  Vanuxemi  H.,  0.  lowensis,  0.  ince- 
qualis,  0.  prava,  Stropheodonta  arcuata  H.,  S.  nacrea  H.,  S.  reversa  H.,  S.  demissa, 
S.  perplana,  Productus  dissimilis  H.,  Productella  pyxidata  H.,  P.  subalata  H.,  Productus 
Shumardianus  H.,  Spirifer  Hungerfordi,  S.  Whitneyi  H.,  S.  fimbriatus  Con.,  8.  bimesia- 
lis  H.,  S.  asper  H.,  S.  Parryanus  H.,  S.pennatus  Owen,  S.  Marionensis  Shumard,  Cyrtina 
umbonata  H.,  C.  triquetra  H.,  Gypidula  occidentalis  H.,  Atrypa  aspera,  A.  reticularis, 
Euomphalus  cyclostomus  H. 


4.    CHEMUNG  PERIOD,  OR  LATER  DEVONIAN. 
ROCKS— KINDS  AND  DISTRIBUTION. 

The  Chernung  Period  includes  (1)  the  PORTAGE  epoch,  represented  by 
the  Genesee  shale  below,  and  the  true  Portage  group  above ;  and  (2)  the 
CHEMUNG  epoch.  The  Catskill  group,  which  has  usually  been  made  to  repre- 
sent a  third  epoch,  is  mainly,  as  stated  on  page  576,  the  sea-border  part  of 
the  Upper  Devonian. 

The  Genesee  shale,  at  the  base  of  the  Portage,  is  black  and  bituminous, 
like  the  Marcellus  shale,  and  rather  sparingly  fossiliferous.  It  is  100  to 
150  feet  thick  in  central  New  York,  along  Cayuga  Lake,  where  it  overlies. 


PALEOZOIC    TIME  —  DEVONIAN.  60S 

the  Tully  limestone,  and  25  feet  on  Lake  Erie,  and  200  to  300  in  west  central 
Pennsylvania.  Along  one  or  two  levels  there  are  great  numbers  of  large 
and  small  calcareous  concretions  which  are  often  septate  (page  97),  so  as 
to  make  the  concretions  look  a  little  like  the  backs  of  turtles.  In  western 
New  York  a  layer  of  bituminous  limestone,  six  inches  to  two  feet  thick, 
occurs  near  the  middle,  which  is  mostly  made  up  of  shells  of  a  Pteropod, 
the  Styliolina  fissurella  Hall  (Fig.  916),  and  is  called  the  Styliolina  lime- 
stone. With  it  occur  remains  of  fossil  fishes,  Dinichthys,  Palceoniscus,  and 
other  species. 

The  Portage  group,  of  New  York  (so  named  from  the  village  of  Portage, 
Livingston  County,  N.Y.),  outcrops  along  a  wide  belt  extending  eastward 
from  the  south  shore  of  Lake  Erie.  It  is  well  displayed  about  the  south 
end  of  Cayuga  and  Seneca  lakes.  Its  beds  are  shales  and  flags,  or  shaly 
sandstones,  —  the  Naples  group,  —  and,  above  these,  the  Portage  sandstone, 
which  has  relations  to  the  Chemung.  The  rocks  have  a  thickness  of  1000 
feet  on  the  Genesee  River,  and  1300  to  1400  near  Lake  Erie.  The  rocks  are 
in  general  very  sparingly  fossiliferous.  They  abound  in  ripple-marks  and 
mud-cracks,  and  the  sandstones  are  often  cross-bedded.  But  a  portion  in 
central  New  York,  called  the  Ithaca  group,  —  prominently  displayed  on  the 
Cascadilla  and  Fall  creeks,  near  Ithaca,  —  abounds  in  fossils.  According  to 
H.  S.  Williams,  the  fossils,  which  are  largely  Brachiopods,  have  near  relations 
to  those  of  the  Chemung  group,  and  also  about  as  close  to  Hamilton  species ; 
and  as  they  are  overlaid  by  5QO  or  600  feet  of  sandstones,  mostly  barren,  but 
containing  some  Portage  species,  they  are  referred  to  the  Portage  group. 
They  are  the  only  part  of  the  beds  that  give  much  knowledge  of  the  life 
of  the  period  ;  and  this  is  imperfect,  as  Trilobites,  Corals,  Crinoids,  and  other 
species  of  purer  waters,  are  absent. 

In  eastern  central  New  York,  in  Delaware,  Otsego,  and  Chemung  counties, 
there  is  a  sandstone  formation,  the  Oneonta  sandstone  of  Vanuxem,  which 
resembles  the  Catskill  beds ;  but  it  is  overlaid  by  beds  containing  Portage 
fossils ;  and  in  some  places,  Chemung  species.  It  indicates  the  existence, 
at  these  localities,  of  Catskill  conditions  during  the  Portage  and  Chemung 
epochs,  if  not  also  during  part  of  the  Hamilton  period.  (H.  S.  Williams.) 
On  the  distribution  of  the  Oneonta  beds,  see  Darton,  Am.  Jour.  Sc.,  1893. 

In  central  and  western  Pennsylvania  the  limit  between  the  Portage  and 
Chemung  is  not  clearly  ascertained.  The  thickness  of  the  two  in  Monroe 
County,  eastern  Pennsylvania,  is  about  2500  feet ;  Fulton  County,  south 
central  Pennsylvania,  about  3600  feet,  of  which  400  are  referred  to  the 
Portage.  Along  the  south  shore  of  Lake  Erie,  the  lower  part  of  the  "  Ohio 
shales "  is  referred  to  the  Portage,  and  the  rest  to  the  Chemung.  Near 
Cleveland,  0.,  the  thickness  of  the  "  Ohio  shales "  is  about  1350  feet,  and 
farther  west,  at  Elyria,  950 ;  but  at  Wellsville  on  the  Ohio,  2600  feet. 

The  Chemung  beds  in  New  York  are  a  continuation  of  the  Portage,  with 
little  change  in  the  rocks,  except  that  they  are  slightly  more  arenaceous, 
and  of  a  lighter  color,  but  with  a  great  change  in  the  abundance  of  fossils  and 


604  HISTORICAL   GEOLOGY. 

in  their  kinds.  They  cover  a  large  part  of  southern  and  western  New  York. 
The  layers  bear  the  same  evidences  of  shallow  waters  as  the  Portage,  and 
are  often  cross-bedded  from  the  sweep  of  the  currents  of  probably  the  tidal 
ebb  and  flow.  The  thickness  south  of  Cayuga  Lake  is  stated  at  1500  feet, 
and  in  Chautauqua  County,  bordering  Lake  Erie,  950  feet.  At  Panama,  in 
this  county,  about  a  dozen  miles  from  the  western  border  of  New  York,  the 
Chemung  rock  is  a  hard,  quartzose  "  flat-pebble  "  conglomerate,  its  pebbles, 
which  are  mostly  of  quartz,  being  commonly  flat.  The  rock  near  Panama 
stands  up  in  bold  bluffs  and  walls,  with  intersecting  passages  and  isolated 
towers,  making  the  place  one  of  the  so-called  "  Kock-cities  "  of  western  New 
York.  The  conglomerate  is  200  to  300  feet  below  the  top  of  the  fossiliferous 
Chemung  of  that  region.  The  rocks  dip  southward  gently,  and  in  the  north- 
western counties  of  Pennsylvania  are  succeeded  by  the  shales  and  sandstones 
of  the  Waverly  group  containing  a  different  fauna. 

The  thickness  of  the  group  is  greater  over  northern  and  central  Pennsyl- 
vania, along  the  Appalachian  area,  becoming  2000  to  8000  feet ;  but,  like  the 
Portage,  it  diminishes  rapidly  westward,  where  it  passes  outside  of  this  area. 

The  Upper  Devonian  is  represented  over  the  larger  part  of  the  Central 
Continental  Interior  by  a  "Black  shale,"  a  stratum  10  to  200  feet  thick, 
carbonaceous,  but  not  always  black.  At  Burlington,  Iowa,  it  includes  some 
limestone.  It  indicates  nearly  uniform  conditions  of  level  over  a  great 
extent  of  surface,  but  with  variations  only  between  salt  or  brackish  and  fresh 
waters.  Its  fossils  are  mainly  small  Brachiopods,  Ceratiocarids,  and  Fishes. 

The  Catskill  group  —  so  named  from  the  Catskill  Mountains  of  eastern 
New  York  —  consists  of  sandstones,  often  passing  into  conglomerates,  with 
some  shale.  The  beds  are  usually  red,  but  occur  also  of  greenish  and  other 
shades.  They  are  rarely  fossiliferous;  and  the  few  animal  fossils  found 
are  those  of  Fishes,  Eurypterids,  and  some  fresh-water  Lamellibranchs.  A 
prevailing  red  color,  and  no  marine  fossils,  are  its  accepted  characteristics ; 
but  these  are  poor  criteria  for  separation  chronologically  from  the  Chemung. 
Hall  was  the  first  to  show  that  they  were  in  part  Chemung.  H.  S.  Williams 
has  recently  referred  the  whole  to  the  Upper  and  Middle  Devonian,  and 
speaks  thus  of  its  relation  in  position  over  the  state  of  New  York  to  the 
rocks  of  these  periods :  "  In  the  G-enesee  section  in  western  New  York, 
the  whole  of  Devonian  time  is  recorded  without  any  trace  of  the  Catskill 
formation ;  it  is  neither  above,  below,  nor  within  the  Chemung.  One  hundred 
miles  eastward,  the  section  running  through  Cayuga  Lake  shows  at  the 
close  of  the  Devonian,  after  the  cessation  of  the  Chemung  fauna,  a  Catskill 
formation  several  hundred  feet  thick.  Another  hundred  miles  eastward, 
across  Otsego  County,  the  section  contains  (1)  rocks  of  the  Catskill  formation 
for  the  upper  third  of  the  Upper  Devonian;  below  these  (2)  a  sparsely 
fossiliferous  zone  of  Chemung  —  probably  its  lower  part,  and  (3)  a  modified 
Ithaca  fauna;  then  (4)  the  Oneonta  formation,  which  is  but  a  detached  zone 
of  the  Catskill;  next  (5)  a  fauna  intermediate  between  that  of  the  Ithaca 
and  the  typical  Hamilton,  underlaid  by  (6)  the  Hamilton  formation  of  the 


PALEOZOIC    TIME  —  DEVONIAN.  605 

Middle  Devonian.  Still  farther  east,  along  the  Hudson  Eiver  valley,  the 
Catskill  formation  occupies  the  whole  of  the  Upper  Devonian  interval." 
The  beds  show  that  the  region  of  their  depositions  was  invaded  here  and 
there  at  times  by  fresh  waters  from  the  bordering  hills. 

In  the  Catskill  Mountain  region  the  Catskill  rocks  are  to  a  large  extent 
the  summit  rocks  and  have  a  thickness  there  of  3000  feet.  Marking  them, 
as  is  usual,  by  their  coarse  sandstone  character  and  red  color,  they  extend 
southwestward  into  Pennsylvania,  along  the  course  of  the  Appalachian 
trough,  from  Port  Jervis,  N.Y.,  to  Fulton  County,  and  have  a  reported 
thickness,  in  this  part  of  the  state,  of  4500  to  7000  feet  ;  3430  at  Port  Jervis, 
4000  to  5300  in  Monroe  County,  Pa.,  7544  near  Mauch  Chunk,  6000  in  Perry 
County,  and  3900  in  Fulton  County.  In  Fulton  County,  Chemung  fossils 
have  been  observed  in  the  so-called  Catskill  beds  by  J.  J.  Stevenson,  through 
the  lower  900  feet,  reducing  the  thickness  of  the  so-called  Catskills  at  that 
point  to  3000  feet.  West  of  the  above-mentioned  line,  the  reported  thickness 
diminishes;  in  southwestern  Bedford  County,  it  being  bat  2000  feet,  and 
only  a  few  feet  in  western  Somerset  County. 

Eastern  New  York  and  Pennsylvania  continued  to  be  for  a  long  time  a  sea- 
border  region,  undergoing  the  subsidence  required  for  thousands  of  feet  of  sea- 
shore deposits,  because  here  lay  the  border  of  the  Appalachian  geosyncline. 

The  Portage  group  was  early  called  the  Nunda  group,  from  this  early  name  of  the 
village  of  Portage,  situated  on  the  banks  of  the  Genesee  River,  where  the  beds  occur. 
The  Genesee  shale  is  finely  displayed  at  the  opening  of  the  gorge  of  the  Genesee  at  Mount 
Morris  ;  and  it  also  forms  high  cliffs  above  the  Tully  limestone  along  the  borders  of 
Cayuga  and  Seneca  lakes.  The  concretions  occurring  in  the  rocks  sometimes  contain  min- 
eral oil,  and  a  soft  substance  looking  like  spermaceti.  The  region  of  the  Portage  beds  in 
New  York  is  famous  for  its  waterfalls. 

On  the  Genesee  River,  the  group  includes,  above  the  Genesee  shale,  (1)  the  Cashaqua 
shale,  and  the  Gardeau  shale  and  sandstones,  the  Naples  beds  of  J.  M.  Clarke  ;  and 
(2)  the  Portage  sandstones.  The  Portage  beds  of  western  Pennsylvania  are  so  deeply 
buried  that  their  thickness  is  unknown  ;  the  drillings  for  oil  do  not  reach  down  to  them. 

The  Ithaca  group  abounds  in  ripple-marks,  mud-cracks,  calcareous  concretions,  and 
cone-in-cone  forms.  It  is  referred  by  Hall  to  the  Chemung  series. 

Prosser  has  deduced  from  the  many  drillings  in  western  New  York,  and  the  observa- 
tions of  Hall,  H.  S.  Williams,  and  others,  the  following  section  for  the  region  not  far 
west  of  the  Genesee  River,  near  Rochester  :  — 

Feet  Feet 

Wolf  Creek  Conglomerate      .  300  Salina?  (to  4000'  d.)     ...  600 

Chemung  (to  1450'  depth)      .  1150  Niagara  and  Clinton      ...  250 

Portage  ........  900  Medina  ........  1158 

Genesee  shale  ......  100  Hudson,  Utica     .....  598 

Hamilton  (to  3200'  d.)  .     .     -  750  Trenton  (to  6960'  d.)    ...  954 

Marcellus  shale    .....  50  Calcif  erous  ?  (to  Archaean  ?)  .  137 


Corniferous 
Lower  Helderberg? 


1 

.     .     .     .  / 


In  Pennsylvania,  in  Perry  County,  the  Chemung  is  3300'  thick,  and  the  Catskill  6000' 
(Claypole)  ;  but  the  latter  contains  in  its  lower  third  some  Chemung  fossils.     In  Columbia 


606  HISTORICAL   GEOLOGY. 

•County,  where  the  Catskill  is  made  4500'  thick,  2300'  to  2443'  are  referred  to  the  Cheraung 
and  Portage  (I.  C.  White).  Above  lies  a  transition  Catskill-Chemung  group  of  1000', 
regarded  as  transitional  because  they  are  so  in  color,  and  contain  some  Chemung  fossils  ; 
and  to  the  west,  the  true  Catskill  group  wholly  disappears  ;  that  is,  the  rocks  have  nothing 
of  the  Catskill  characteristics. 

In  Prosser's  section  in  Monroe  County,  Pa.,  referred  to  on  page  594,  he  found  the  beds 
to  correspond  to  the  Portage,  Oneonta,  and  Chemung,  through  a  thickness  of  3050', 
and  to  include  the  Chemung  beds  of  White,  and  the  overlying  Starucca  sandstone,  600', 
New  Milford  shales,  100',  and  the  Delaware  flags,  1200'.  Above  come  the  Montrose 
•shales  and  the  so-called  Catskill  beds,  the  last  consisting  of  the  Honesdale  sandstone,  the 
Cherry  Ridge  group,  325',  the  Elk  Mountain  sandstone  and  shale,  200',  and  the  Mount 
Pleasant,  1150',  Red  shale,  300' ;  about  2000'  in  all. 

The  "Black  shale"  of  the  Central  Interior  occurs  in  Indiana,  at  the  Falls  of  the 
Ohio,  with  Genesee  shale  fossils  at  its  base  ;  in  Kentucky,  200'  thick  in  the  northeast  part, 
and  diminishing  southwestward.  In  Illinois  it  is  40'  to  60'  thick,  the  thickest  along  the 
Ohio ;  it  contains  a  Genesee  Lingula.  In  Tennessee,  through  much  of  the  state,  it  is 
100'  thick  and  less.  Owing  to  denudation,  it  is  not  found  in  central  Tennessee.  In  Ar- 
kansas and  Missouri,  its  equivalent,  the  Eureka  shale,  is  0'  to  50'  thick. 

In  Ohio,  the  Ohio  shales  include  the  Cleveland  shale,  Erie  shale,  and  Huron  shale  of 
Newberry  ;  a  belt  of  it,  10  to  20  miles  wide,  and  several  hundred  feet  thick,  stretches 
across  Ohio  from  Lake  Erie  to  the  Ohio  Valley,  and  is  noted  for  its  calcareous  and 
ferruginous  concretions ;  the  lower  part  corresponds  to  the  Huron  shale,  and  the  upper 
beds  to  the  Cleveland  shale.  At  its  base,  or  directly  below  it,  Hamilton  fossils  have  been 
found ;  but  above,  a  few  Portage  and  Chemung  species.  The  Cleveland  shale  has 
afforded  many  remains  of  Fishes.  The  Perry  sandstones  of  southern  New  Brunswick  are 
.mentioned  on  page  594. 

The  yellow  sandstone  at  Pine  Cove,  Muscatine  County,  Iowa,  and  the  Ro'ckford  shale 
"belong  near  the  base  of  the  Chemung. 

In  a  paper  by  Darton  (1893)  it  is  proposed  to  adopt  the  name  Catskill  for  the  period 
including  the  Chemung  and  Portage.  But,  as  has  been  shown,  it  has  not  the  fossils  that 
would  entitle  it  to  such  a  position.  In  fact,  the  name  Catskill  has  no  right  to  a  place  in 
the  time  series.  Its  introduction  was  from  the  first  an  error. 

In  the  Arctic  regions,  on  the  eastern  part  of  the  north  coast  of  Grinnell  Land,  at 
Dana  Bay,  occurs  an  area  of  rocks  containing  Productus  mesolobus  or  costatus,  a  Spirifer, 
etc.,  which  are  referred  by  the  authors  to  Devonian  (Feilden  &  De  Ranee,  Q.  J.  G.  $., 
xxxiv.,  1878)  ;  but  these  fossils  are  Carboniferous. 

An  interesting  excursion  in  eastern  New  York,  for  the  study  of  the  Devonian  series, 
may  be  had  by  going  to  Catskill  Village,  and  passing  westward  over  the  hills  at  the  base 
of  the  Catskill  Mountains.  Over  the  Hudson  River  slates  lies  the  water-lime  of  the  Middle 
Upper  Silurian  ;  then  the  successive  subdivisions  of  the  Lower  Helderberg.  Beyond  lies 
the  Corniferous  limestone  of  the  Lower  Devonian ;  then  the  Marcellus  shale  and  Hamilton 
sandstones.  Moreover,  the  flexures  of  the  rocks  are  instructive.  See  W.  M.  Davis  on 
the  Little  Mountains,  Appalachia,  1882,  page  20. 

Rondout,  N.Y.,  on  the  Hudson  River,  affords  a  section  from  the  Hudson  beds  to  the 
Corniferous  inclusive,  part  quite  fossiliferous,  and  the  line  of  a  great  fault  above  the  Hudson 
beds,  and  is  another  good  place  for  the  geological  student.  See  W.  M.  Davis,  Am.  Jour. 
•8c.,  1883,  vol.  xxvi. 

The  Devonian  series  of  the  Pahranagat  Range,  central  Nevada,  is  3000'  thick,  and  is 
fossiliferous.  It  ~ests  on  the  Silurian.  For  notes  on  the  Upper  Devonian  of  the  Eureka 
district,  see  pages  589,  592. 

Mineral  oil  and  gas.  —  The  upper  part  of  the  Upper  Devonian  is  the 
-chief  source  of  the  mineral  oil  and  gas  of  Pennsylvania.  The  drillings 


PALEOZOIC   TIME  —  DEVONIAN.  607 

descend  to  a  coarse  oil-yielding  porous  sandstone  called  an  oil-sand;  and 
on  reaching  it,  the  oil,  if  the  well  is  successful,  usually  rises  to,  or  above,  the 
surface ;  or  if  a  gas  well,  the  gas  comes  out  with  great  force.  The  number 
of  different  oil-sands  in  a  region  is  one  to  three;  they  are  confined  to 
about  300  feet  in  thickness  of  the  beds,  and  each  is  20  to  60  feet,  or  more, 
thick.  The  productive  counties  lie  in  a  belt,  nearly  northeastward  in  course, 
from  Greene  County,  in  the  southwest  part  of  the  state,  to  McKean  County, 
on  the  northern  border ;  and  they  pass  this  border  into  Alleghany  County,  N.  Y., 
and  also  on  the  south,  into  Monongalia  County,  W.Va.  See  map,  page  731. 
In  the  counties  from  Warren  to  Washington  the  oil-sands  are  within  400  feet 
of  the  summit  of  the  Devonian ;  in  the  part  of  the  belt  more  to  the  northeast,  in 
McKean  County,  and  in  New  York,  they  are  in  its  lower  part,  or  between  1200 
and  1800  feet  of  the  summit.  The  latter  is  a  high  region,  the  surface  1800 
to  2600  feet  above  the  sea  level.  The  wells  often  let  up  much  salt  water  from 
different  levels.  Frequently  water  rises  with  the  oil  or  gas,  making  the  well 
valueless  unless  tubing  to  the  bottom  will  exclude  the  water. 

The  oil-sands  are  coarse,  open-textured  sandstones  —  so  open  in  texture 
that  they  are  able  to  hold  a  vast  amount  of  oil  in  the  spaces  between  the 
grains.  All  the  oil-bearing  regions  are  also  gas-producing ;  but  the  well  is 
available  for  gas  only  when  the  latter  comes  to  the  surface  free  from  oil  as 
well  as  water.  Moreover,  the  gas  is  abundant,  according  to  I.  C.  White, 
only  where  the  rocks  passed  through  in  the  drilling  lie  in  a  low  anticline.  The 
open-textured  sandstones  are  possibly  sandstones  that  have  lost  the  finer 
material  between  the  grains  by  percolating  waters.  As  some  of  the  Chemung 
beds  are  more  or  less  calcareous,  they  may  originally  have  been  calcareous 
sand-beds,  and  have  become  porous  by  the  removal  of  the  calcareous  part ; 
but  this  is  only  conjecture. 

The  oil  is  usually  projected  in  jets,  and  the  power  has  been  shown  to  be 
Artesian,  or  hydrostatic,  by  I.  C.  White,  in  agreement  with  Orton's  view  for 
the  Trenton  limestone  gas  of  Ohio  and  Indiana.  A  well  near  Kane,  in 
McKean  County,  Pa.,  drilled  to  a  depth  of  2000  feet,  in  1878,  but  abandoned 
because  of  the  small  yield  of  oil,  became  afterward  a  water-and-gas  geyser, 
gas  and  not  steam  being  the  moving  agent.  Fig.  925  is  from  a  photograph 
received  in  1879  by  the  author  from  C.  A.  Ashburner,  accompanying  a 
description  by  him  of  the  geyser.  The  well  at  that  time  threw  up  a  column 
of  water  and  gas,  at  intervals  of  10  to  15  minutes,  to  heights  varying  from 
100  to  150  feet.  On  August  2d  four  successive  jets  had  heights  of  108, 
132,  120,  and  138  feet.  When  the  gas  of  the  columns  was  lighted  at  night, 
"the  antagonistic  elements  of  fire  and  water  were  promiscuously  blended, 
at  one  moment  the  flame  being  almost  extinguished,  but  only  to  burst  forth 
the  next  instant  with  increased  energy  and  greater  brilliancy."  Mr.  Ash- 
burner  explains  the  action  thus :  "  The  water  flows  into  the  well  on  top  of 
the  gas  until  the  pressure  of  the  confined  gas  becomes  greater  than  the 
weight  of  the  superincumbent  water,  when  an  explosion  takes  place,  and  a 
column  of  water  and  gas  is  thrown  to  a  great  height."  The  gas  comes 


608 


HISTORICAL    GEOLOGY. 


925- 


from  the  deep-seated  rock  that  has  yielded  also  the  oil,  and  some  higher  tem- 
perature than  that  of  the  surface  was  needed  for  its  production.     At  a  depth 

of  1415  feet  in  the  drilling  a  very  heavy 
"gas  vein"  was  struck,  and  this  was- 
the  chief  source  of  the  gas.  Ashburner 
remarks  further  that  several  other  wells 
in  the  oil-regions  have  had  similar  gey- 
sers ;  and  as  early  as  1833,  in  the  valley 
of  the  Ohio,  a  salt  well  threw  jets  of 
water  and  gas,  at  intervals  of  10  to  12 
hours,  to  heights  of  50  to  100  feet. 

The  original  source  of  the  oil  is  sup- 
posed,  by  most  writers  on  the  subject, 
to  have  been  a  Devonian  shale,  like  the 
Genesee  or  Marcellus,  below  the  level 
of  the  Chemung  beds,  from  which  it- 
was  evolved  by  a  slow  process  of  distil- 
lation. The  conditions  necessary  for 
oil,  on  this  view,  are  (1)  a  primary 
source  of  the  oil  ;  (2)  strata  to  receive 
and  hold  it  ;  and  (3)  overlying  deposits 
to  prevent  its  escape  to  the  surface  and 
consequent  dissipation.  These  three 
conditions  are  fulfilled  by  (1)  a  deep- 
seated  carbonaceous  rock  containing 
abundant  organic  remains;  (2)  an  over- 
tying  porous  stratum;  and  (3)super- 
incumbent  shales,  slates,  etc.  These 

statements  also  apply  to  gas  production.  Slight  subterranean  movements 
attending  the  making  of  the  Appalachian  Mountains  to  the  east  and  south- 
east would  have  produced  some  heat,  and  so  have  caused  oil  to  escape  from 
the  shales;  and  the  .vaporized  oils  would  have  risen  until  they  were  some- 
where condensed  —  either  in  confined  places  in  or  among  the  rocks,  or  still 
higher  in  the  open  air  (Peckham,  1884).  I.  C.  White  regards  the  source  as- 
organic  materials  within  the  sand-beds. 


-gas  geysen 


The  oil  wells  of  western  Pennsylvania  yielded,  in  1891,  31,793,477  barrels  of  the  crude 
oil,  or  petroleum.  Of  this,  5,452,418  barrels  were  from  the  Bradford  district,  McKean 
County,  and  10,317,258  from  Alleghany  County,  the  county  of  which  Pittsburg  is  the 
capital.  In  the  same  year,  the  yield  of  Alleghany  County,  N.Y.,  adjoining  the  northern 
end  of  the  Pennsylvania  belt,  was  1,121,574  barrels;  and  that  of  West  Virginia,  adjoining 
the  southern  end,  2,406,218  barrels.  The  total  yield  of  the  United  States  in  1891  was 
54,291,980  barrels.  Ohio  produced  17,740,307  barrels,  making  the  yield  for  Pennsylvania 
and  Ohio  together  49,533,784  barrels.  But  the  oil  of  Ohio  was  nearly  all  from  the  Lower 
Silurian  Trenton  limestone  —  this  formation  affording  17,316,000  barrels;  the  Berea  grit,, 
which  is  referred  to  the  Subcarboniferous,  supplied  only  a  few  hundred  thousand  barrels- 


PALEOZOIC   TIME  —  DEVONIAN. 


609 


A  barrel  equals  42  gallons.  The  yield  of  Pennsylvania  in  1859  was  2000  barrels ;  in  1860, 
500,000 barrels;  in  1870,  5,260,234  barrels;  in  1880,  over  26,000,000  barrels.  In  1892,  the 
yield  was  over  4,000,000  barrels  less  than  in  1891. 

For  a  report  on  the  oil  and  gas  regions  of  Pennsylvania,  with  maps,  see  Rep.  I  5,  of 
the  Penn.  Geol.  Surv.,  by  John  F.  Carll,  1890 ;  and  for  Ohio,  Rep.  vol.  vi.,  on  Economic 
Geology,  by  E.  Orton,  1888  ;  and  for  Kentucky,  Rep.  by  E.  Orton,  1891 ;  and  for  Statistics, 
Mineral  Resources  of  the  U.  S.,  by  D.  T.  Day,  8vo. ;  U.  S.  G.  S.,  volumes  for  1891  and 
1892,  issued  in!893. 


926-930. 
929. 


927. 


926. 


Fig.  926,  Archaeopteris  Halliana ;  927,  A.  minor ;  928,  Aneimites  obtusus ;  929,  Sigillaria  Vanuxemi ;  930,  Lepl- 
dodendron  Chemungense.     Figs.  926,  930,  Hall ;  927,  928,  Lesquereux  ;  929,  Vanuxem. 

DANA'S  MANUAL  —  39 


610 


HISTORICAL   GEOLOGY. 


LIFE. 

PLANTS.  —  In  the  Portage  the  remains  of  land  plants  are  rare.  There  are 
stems  of  species  of  Lepidodendron  —  L.  Chemungense  and  L.primcevum;  of 
Lycopodites  and  Knorria;  of  Cyclostigma — C.  affine  Dn. ;  of  Calamites  — 
Bornia  inornata  Dn.;  of  Tree-ferns,  Asterochlcena  (Asteropteris)  Noveboracensis 
Dn.,  from  Milo,  N.Y. ;  and  woods  of  Gymnosperms,  as  Cordaites  (formerly 
Dadoxylon}  Clarki  Dn.  Sporangites  ($.  Huronensis)  occur  in  the  more  bitu- 
minous portions  of  the  Genesee  shale. 

931. 


Dictyo-cordaites  Lacoei,  Dawson  (1):  a,  venation  of  leaf ;  6,  fruit  enlarged.    Dawson,  '89. 

The  Chemung  land  plants  discovered  include  those  of  the  Portage  and 
others.  Some  of  them  are  represented  on  page  609.  Figs.  926,  927,  928  show 
portions  of  plants  from  the  Chemung  of  Gilboa,  K Y. ;  928,  from  the  Catskill 
beds  of  Montrose,  Pa. ;  929,  from  Pottsville,  Pa.,  and  Franklin,  N.Y.  The 


PALEOZOIC   TIME  —  DEVONIAN. 


611 


Pottsville  specimen  of  Aneimites  obtusus  Lx.  (Fig.  928)  was  over  a  foot  across. 
A  Tree-fern  also,  Caulopteris  Lockwoodi  Dn.,  has  been  obtained  at  Gilboa.  Fig. 
929  represents  a  Sigillaria  from  the  Chemung  of  Owego,  N.Y.,  and  930,  a 
Lepidodendron  from  Elmira,  N.Y.,  the  latter  with  very  small  leaf-scars. 
In  the  specimen  of  Fig.  929,  the  upper  part  shows  the  scars  as  they  appear 
on  the  inner  surface  of  the  bark.  Specimens  of  L.  Gaspianum,  of  the  Lower 
Devonian,  and  some  other  species,  have  also  been  found  in  the  Chemung 
beds  of  New  York ;  and  L.  corrugatum  of  Dawson  in  the  Chemung  of  Ohio, 
and  also  at  the  base  of  the  Carboniferous  near  Pottsville,  Pa.,  and  in  Vir- 
ginia. The  Gaspe  species  accompanying  the  Pterichthys  Canadensis,  and  indi- 
cating thereby  that  the  beds  are  Upper  Devonian  (Dawson),  are  Archceopteris 
Gaspiensis  Dn.,  Aneimites  obtusus  Lesq.,  and  Rhacophyllum  Broivnii  Dn. 

Fig.  931  represents  a  remarkable  plant  from  beds  in  Wyoming  County, 
Pa.,  referred  to  the  lower  part  of  the  Catskill  series.  Dawson  regards  it  as 
belonging  to  the  Cordaites  group,  under  Gymnosperms.  The  fruit  enlarged 
is  shown  at  b. 

The  black  shales  of  the  Upper  Devonian  in  New  York,  Canada,  Ohio,  and 
elsewhere,  like  those  of  the  Lower  Devonian,  abound  in  Sporangites  (page 
596).  The  facts  show  that  the  simple  plants  —  the  Rhizocarps —  were,  as 
Dawson  states,  very  abundant  in  the  waters.  Dawson  speaks  of  the  spores 
as  "  dispersed  in  countless  millions  of  tons  through  the  Devonian  shales  of 
Canada  and  the  United  States,"  and  as  being  the  source  of  their  black  color 
and  their  oil-yielding  character. 

ANIMALS.  1.  Spongiozoans. — The  network  hexactinellid  Sponge,  Dicty- 
ophyton  tuberosum  of  Conrad,  occurs  in  the  Chemung,  where  there  are  also 
other  species  of  the  genus.  Uphantcenia  Chemungensis  of 
Vanuxem  is  another  peculiar  glass  Sponge  of  the  Chemung, 
found  near  Owego,  N.Y.,  first  referred  to  the  Sponges  by 
Whitfield. 

2.  Corals  and  Crinoids.  —  These  are  not  common  in 

the  Portage  or  Chemung  group.  Some  calcareous  beds  of 
the  Chemung  have  afforded  Corals  of  the  geneva,  Zaphrentis 
and  Heliophyllum  (near  H.  Halli  of  the  Hamilton);  also 
remains  of  Crinoids,  showing  that  these  animals  were 
absent  from  the  Upper  Devonian  only  because  the  con- 
ditions of  the  New  York  and  the  bordering  seas  were 
unfavorable ;  they  were  back  when  the  seas  were  again 
of  sufficient  purity. 

3.  Molluscoids.  —  Some    of    the    few    Genesee    and 
Portage    Brachiopods    are   represented   in  Figs.  933  to 

936.  In  the  lettering  underneath  the  cut  the  letters  G.  SPONGE.  —  Dictyophyton 
and  P.  are  initials  of  Genesee  and  Portage.  Besides  tuberosum. 

the  genera  represented  in  the  figures,  Chonetes  and  Productella  are  also 
prominent. 


932. 


612 


HISTORICAL   GEOLOGY. 


Brachiopods  were  far  more  numerous  in  the  Chemung  beds  than  in  the 
Portage.  The  figures  939  to  942  represent  common  species ;  941,  an  Atrypa 
of  ornate  type,  like  the  young  of  A.  reticularis;  940,  a  species  of  Productella. 


933. 


933-938. 


934. 


BBAOHIOPODS.  —  Fig.  933,  Spirifer  laevis  (P.)  ;  934,  Leiorhyncus  quadricostatum  (G.)  ;  935,  Lingula  spatulata,  (x  3) 
(G.) ;  936,  Orbiculoidea  Lodensis,  (x  2)(G.).  LAMELLIBRANCHS.  —  Fig.  937,  Lunulicardium  fragile  (G.  and  P.); 
938,  Glyptocardia  speciosa  (G.  and  P.).  Hall,  except  Fig.  934,  King. 

4.  Mollusks.  —  Lamellibranchs  were  few  in  the  Portage,  but  very  numerous 
in  the  New  York  and  Pennsylvania  Chemung  beds,  outnumbering  all  other 
Mollusks.  Hall  describes  252  Chemung  species,  and  only  11  from  the 
Portage  and  Genesee  beds,  with  174  from  the  Hamilton.  Figs.  939,  940, 
943,  944,  945,  represent  some  common  forms.  A  compressed  specimen  of  a 
New  York  Catskill  species  is  represented  in  Fig.  948.  It  has  the  form  of  a 
freshwater  Unio,  and  the  name  Amnigenia,  of  Hall,  alludes  to  its  suspected 
freshwater  habitat.  It  is  from  the  "  Oneonta  sandstone  "  of  Chenango  and 
Otsego  counties,  N.Y.,  and  has  been  found  also  in  the  Catskill  beds  of  Bedford 
County,  Pa. 

The  "  Black  shale  "  of  Ohio  and  the  states  west  and  south,  which  repre- 
sents the  Genesee  with  more  or  less  of  the  Portage  and  Chemung  beds,  is 
remarkable  for  the  great  rarity  of  fossils.  In  Ohio  the  lower  beds  have 
afforded  the  Portage  species  :  Chonetes  scitulus,  Ooniatites  complanatus,  Coleo- 
lus  acicula,  Styliolina  fissurella  ;  and  the  upper  and  middle  portion,  the 
Chemung  species:  Leiorhynchus  mesacostale,  Spirifer  disjunctus,  S.  altus; 
also  species  of  Lingula  and  Orbiculoidea.  Southern  Indiana  has  afforded 
Lingula  spatulata,  Discina  (Schizobolus)  truncata,  Chonetes  lepidus,  Leiorhyn- 
chus quadricostatum  (Genesee  species),  L.  limitare  (a  Marcellus  sp.),  Styliolina 
fissurella.  Fossil  plants  also  are  rare  ;  but  wood  of  Gymnosperms,  referred 
to  Dadoxylon  and  Cordaites,  is  found  in  it.  In  most  parts  of  the  shale, 
Sporangites  are  in  great  abundance,  S.  Huronensis  of  Dawson,  -^  to  -3-^5- 
inch  in  diameter. 

Gastropods  are  few  in  both  the  Portage  and  Chemung  beds.  The  prolific 
genera  of  the  earlier  Devonian,  Platyceras  and  Platystoma,  have  a  number 


PALEOZOIC   TIME  —  DEVONIAN. 


613 


of  species.     The  genera  having  the  most  of  the  species  are  Loxonema,  Cydo- 
nema,  and  Bellerophon.     Conularice  are  not  uncommon. 


939-947. 


939. 


943. 


944. 


BBACHIOPODS,  Chemung.  —  Figs.  939,  939  a,  Khynchonella  contracts  ;  940,  940  a,  Productella  lacrymosa ;  941, 
Atrypa  hystrix;  942 a,  6,  Spiriferdisjunctus.  LAMELLIBRANCHS.  —Fig.  943,  Aviculopecten  duplicates  ;  944, 
Pterinea  Chemungensis  ;  945,  Leptodesma  lichas.  GASTROPOD.  —  Fig.  946,  Bellerophon  maera  ;  947,  Bactrites 
acicula.  From  Hall. 

948. 


LAMELLIBBAKCH,  Catskill.  —  Amnigenia  Catskillensis.    Vanuxem. 

Cephalopods  are  few,  except  under  the  genera  Goniatites  and  Orthoceras. 
The  thin  Styliolina  limestone  bed  in  the  Genesee   shale   contains   several 


614 


HISTORICAL  GEOLOGY. 


species  of  Goniatites  and  Orthoceras,  and  a  few  other  species.     The  Naples 
beds,  in  the  Lower  Portage,  have  afforded  the  first  of  American  species  of 


949-953. 


949. 


953. 


954. 


Fig.  949,  Clymenia  Neapolitans,  of  New  York  (x  4) ;  950,  profile  of  same  ;  951,  transverse  section  near  beginning 
of  5th  whorl ;  952,  same  at  end  of  1st,  2d,  3d,  and  4th  whorls ;  953,  form  of  the  suture  at  2$  revolutions. 
J.  M.  Clarke. 

Clymenia  (Fig.  949),  a  genus  related  to  Nautilus,  but  having  the  siphuncle 
dorsal  (Fig.  951).  Fig.  954  represents  Goniatites  intumescens  (G.  Patersoni 
Hall)  of  the  same  beds ;  it  occurs  also  in  the  Ithaca  group. 

The  so-called  Catskill  beds  contain  no 
remains  of  marine  Mollusks  of  any  kind, 
except  occasionally  such  as  are  regarded  as 
Chemung,  and  as  indications  that  the  beds 
are  Chemung. 

5.  Crustaceans.  —  Trilobites  have  not  a  re- 
corded species  from  the  New  York  Portage ; 
and   in   the   Chemung  occur  only  Phacops 
nupera  H.,  doubtfully,  and  Cyphasphis  Ice-vis 
H.,    Phacops    rana    and    Dalmanites    (Cry- 
phceus)  Boothi.     But   conditions  were  more 
favorable   in  Ohio,  and  a  Chemung  fauna, 
according  to  Herrick,  has  afforded  the  follow- 
ing species  :  Proetus  minutus  Hk.,  P.  prcecursor,  P.  doris  Winchell,  P.  auric- 
ulatus  H.,  Phcethonides  occidentalis  Hk.,  P.  spinosus  Hk.,  and  others. 

Phyllopod  Crustaceans  were  of  various  forms  and  species  in  the  Portage, 


Goniatites  Patersoni  Hall. 


PALEOZOIC   TIME  —  DEVONIAN.  615 

and  besides  these,  there  are  the  first  of  true  Shrimps,  or  Macrural  Decapod 

965-958. 


958. 


957. 


POBTAGE.  —  Fig.  955,  Mesothyra  Ocean! ;  956,  Dipterocaris  penna  Dsedali ;  957,  D.  Procne ;  958,  Palseopatemon 
Newberryi.    Fig.  955,  Hall ;  956,  957,  J.  M.  Clarke ;  958,  Whitfield. 


Crustaceans,  Palceopalcemon  Newberryi  of  Whitfield  (Fig.  958). 
Phyllopod  genus  Echinocaris  of  the  same  author 
there  are  a  number  of  species  ;  and  the  related  Me- 
sothyra  Oceani  of  Hall  (Fig.  955)  had  a  length  and 
breadth  of  more  than  10  and  5  inches.  Figs.  956 
and  957  represent  carapaces  of  two  other  Phyllo- 
pods.  The  specimen  of  Palceopalcemon  was  found  in 
Ohio,  in  the  lower  part  of  the  Ohio  shale. 

6.  Limuloids.  —  The  lower  beds  of  the  Portage 
and  Upper  Chemung  have  afforded  species  of  Euryp- 
terus.  Also  a  few  abdominal  segments  of  great  size, 
which  have  been  made  the  basis  of  the  species  Stylo- 
nurus  Wrightianus,  supposed  to  have  been  two  feet 
long. 

Of  Catskill  Eurypterids,  one  gigantic  species,  Sty- 
lonurus  excelsior  H.,  has  been  described  from  imper- 
fect specimens  found  in  the  Catskill  beds  of  Delaware 
County,  N.Y.,  and  Wyoming  County,  Pa.  The  cara- 


Under  the 


CHEMTJNG.  — Fig.  959,  Protollm- 
ulus  Eriensis,  ventral  side. 
H.  S.  Williams. 


616 


HISTORICAL   GEOLOGY. 


pace  is  nearly  10  inches  square,  the  toothed-edge  of  the  mandible  1J  inches 
long,  and  the  whole  length  probably  over  4  feet  (Hall).      In  addition,  a 


960-962. 


960  a. 


960. 


PLACODERMS.  — Fig.  960,  Bothriolepis  Canadensis  (x  J),  dorsal  view;  960  o,  id.  ventral  view  ;  from  Whiteaves; 
m.  v.,  middle  ventral  plate;  a.  m.  v.,  anterior  middle  ventral;  a.  v.,  anterior  ventral;  p.  v.,  posterior  ven- 
tral; 961,  terminal  part  of  pectoral  limb  of  a  Bothriolepis  (Cope);  962,  plate  of  a  Bothriolepis  (Leidy). 


963. 


964. 


COOCOBTEID  FISHES. —Fig.  963  restored  ventral  plates  of  Holonema  rugosum  (x  J),  from  H.  8.  Williams; 
964,  restored  ventral  plates  of  Phlyctaenaspis  Acadica  of  Whiteaves  (x  £),  from  Traquair. 


species,  related  apparently  to  Limulus  (Fig.   959),  has  been  found  in  the 


PALEOZOIC   TIME  —  DEVONIAN. 


617 


Chemung  of  Erie  County,  Pa.      It  is  the  Protolimulus  Eriensis  of  H.  S. 
Williams. 

7.  Vertebrates.  —  Remains  of  Placoderms,  of  the  brachiate  type,  or  re- 
lated to  Pterichthys,  have  been  found  in  Ohio  and  in  the  Catskill  sandstone 
of  New  York  and  Pennsylvania,  and  nearly  perfect  specimens  (Figs.  960, 

960  a)  of  one  species,  Bothriolepis  Canadensis  of  Whiteaves,  at  Scaumenac 
Bay  (in  Baie  de  Chaleurs),  New  Brunswick.     Fig.  960  is  a  view  of  the  dorsal 
shield,  and  960  a,  the  ventral,  both  reduced  to  a  third  of  the  natural  size ; 
and  960  shows  also  the  probable  outline  of  the  posterior  extremity,  which 
has  been  added  to  Whiteaves's  figures  from  the  form  in  Pterichthys.     Fig. 

961  represents,  natural  size,  the  finger-like  termination  of  a  fore  limb  of 
possibly  the  same  species,  described  by  Cope,  which  was  found  at  Mansfield, 


965. 


965-969. 


966. 


DIPNOAN  FISHES.  —  Fi?.  965,  Dinichthys  Hertzeri,  front  view  of  jaws  (x  ^);  966,  ventral  plates  (x^,):  967.  palate 
tooth  of  Dipterus  Sherwoodi ;  968,  id.  of  Ctenodus  Nelsoni :  all  from  Newberry.  Fig.  969,  Pliaueropleuron 
curtum  (x|),  from  Whiteaves. 

Tioga  County,  Pa.,  with  remains  of  Holonema.     Fig.  962  represents  a  plate 
of  Bothriolepis  from  the  Catskill  beds. 

No  remains  of  the  posterior  scaly  part  of  the  body  have  been  observed  in 
connection  with  specimens  of  the  American  species  of  Bothriolepis,  though 
occurring  in  Scotland  with  those  of  Pterichthys. 


618 


HISTORICAL   GEOLOGY. 


The  Coccosteus  family  was  represented  by  species  of  large  size.  The 
ventral  plates  of  two  are  represented  on  page  616.  Fig.  963  is  Holonema 
rugosum  of  Claypole;  as  determined  by  H.  S.  Williams,  the  central  plate 
in  the  ventral  shield  (m.  v.)  has  a  length  of  8^  inches.  The  specimen  figured 
is  from  the  Oneonta  sandstone,  near  Oxford,  N.Y.  In  the  related  species, 
Fig.  964,  from  Campbelltown,  New  Brunswick,  the  central  plate  is  but  one 
inch  long. 


970-974. 


970. 


OANOIDS.  —  Fig.  970,  Glyptolepis  Quebecensis  (xf);  971,  Eusthenopteron  Foordi  (x|);  972  ,  scale  from  a  species 
of  Holoptychius  ;  973,  tooth,  id. ;  974,  Chirolepis  Canadensis.    Figs.  970, 971,  974,  Whiteaves  ;  972, 973,  Leidy. 

The  Dipnoans,  or  "Lung-fishes,"  were  represented  by  gigantic  species 
called  by  Newberry  Dinichihys  and  Titanichthys,  from  their  size  and  formi- 
dable dental  armature.  The  species  of  Dinichihys,  to  which  Figs.  965,  966 


PALEOZOIC   TIME  —  DEVONIAN. 


619 


pertain,  were  described  from  specimens  found  in  the  Cleveland  shale  of  Ohio. 
Fig.  965  shows  the  form  of  the  upper  and  lower  jaws  in  natural  position  of 
Dinichthys  Hertzeri.  To  represent  the  natural  size,  the  figure  should  have  a 
breadth  of  45  inches.  Fig.  966  is  the  ventral  shield.  It  resembles  that  of 
Coccosteus,  and  also  that  of  Bothriolepis.  A  still  larger  species  is  the 
Titaniclitliys  Clarki  of  Newberry,  in  which  the  head  was  four  feet  or  more 
broad,  the  lower  jaw  a  yard  long.  This  jaw  was  shaped  posteriorly  like  an 
oar  blade,  and  anteriorly  was  turned  upward  like  a  sled-runner.  Dinichthys 
Oouldi  of  Newberry  had  enormous  eyes  surrounded  by  sclerotic  plates.  The 
Phaneropleuron  of  Whiteaves  (Fig.  969)  is  a  smaller  Dipnoan  from  the 
Upper  Devonian  at  Scaumenac  Bay,  New  Brunswick.  Figs.  967,  968  rep- 
resent the  palate  teeth  of  two  Dipnoan s  ;  such  teeth,  and  the  brachiate  pec- 
toral and  ventral  fins  are  special  Dipnoan  characteristics. 

975-977. 


SELACHIANS.  —975,  Cladodus  sinuatus  (x  J) ;  976,  tooth  of  C.  Clarki ;  977,  C.  Fyleri  (xf ).    Tigs.  975, 976,  Ckypole ; 

977,  Newberry. 

Fig.  970  represents  a  Ganoid  of  Crossopterygian  type — as  indicated  in 
this  figure  by  the  thickened  finger-like  medial  portion  of  the  pectoral  fin  —  a 
structure  better  exemplified  in  Fig.  969.  A  scale  of  a  related  genus, 
Holoptychius,  is  represented,  of  natural  size,  in  Fig.  972,  and  a  tooth,  referred 
to  the  same  genus  by  Leidy,  in  Fig.  973.  (See  also  page  625  for  a  figure  of  a 
nearly  complete  specimen  of  another  species.)  The  genus  Eusthenopteron  of 
Whiteaves  (Fig.  971)  has  special  interest  on  account  (as  the  name  implies) 
of  the  supports  with  which  the  fins  are  provided,  answering  to  the  pectoral 
and  pelvic  arches  of  higher  Vertebrates  —  a,  the  pectoral,  and  6,  the  pelvic 
(only  two  bones  of  which  are  preserved) ;  and  also  the  similar  and  even 
larger  supports  for  the  anal  fin  at  c  and  for  the  posterior  dorsal  at  d,  with  a 


620  HISTORICAL   GEOLOGY. 

like  arrangement,  but  less  perfectly,  for  the  lower  part  of  the  caudal  fin. 
They  gave  the  posterior  part  of  the  body  great  strength  for  sculling.  It  is 
further  to  be  observed  that  the  open  space  along  the  center  of  the  vertebral 
column  indicates  a  persistent  notochord  (cartilaginous),  the  spinous  processes 
being  the  only  calcareous  portions  of  the  column.  Fig.  974  represents  a 
Canada  species  of  Chirolepis,  a  genus  of  the  family  Palseoniscidse.  Palceo- 
niscus  Devonicus  of  Clarke  is  another  Devonian  Ganoid,  from  the  Portage  of 
New  York.  The  species,  Figs.  970,  971,  974,  are  from  Scaumenac  Bay. 

/Selachians,  or  Sharks,  were  represented  not  only  by  fin-spines  and  teeth, 
but  also,  in  the  Cleveland  shale  of  Ohio,  by  impressions  or  remains  of  the 

nearly  entire   body.     Two   speci- 
978.  mens   of  the   latter    are    shown, 

much  reduced,  in  Figs.  975,  977. 

The  largest  yet  found,  Cladodus 

Kepleri,  had  a  length  of  six  feet. 

Newberry's  figure  of  C.  Fyleri,  in 

his    Paleozoic    Fishes    of   North 
SELACHIAN. -Fig.  978,  Acanthodes  affinis;  a,  scales,          America,    gives    it    a    length   of 
natural  size,   whiteaves.  22   inches.     It   is   referred   to   a 

new   genus,  Cladoselacha,   by   B. 
Dean.     The  tooth,  Fig.  976,  is  of  the  species  Cladodus  Clarki  of  Claypole. 

Kemains  of  a  species  of  another  genus,  Acanthodes,  related  to  the  Sharks, 
but  having  minute  square  or  rhombic  scales,  has  been  found  at  Scaumenac 
Bay.  A  small  specimen  is  represented  in  Hg.  978.  Other  species  of  the 
genus  have  been  reported  from  New  York  and  Pennsylvania. 

Characteristic  Species. 

Genesee  shales.  —  Orbiculoidea  Lodensis,  Discina  truncata,  Lingula  spatulata  (also 
Portage),  Chonetes  lepidus  (also  Hamilton),  Amboccelia  umbonata  (also  Ham.  &  Mar.), 
Leiorhynchus  quadricostatum,  Strophalosia  truncata  (also  Marcelltis),  Lunulicardium- 
fragile  (Marcellus  to  Portage),  Cardiola  (Glyptocardia")  speciosa  (Ham.  to  Chemung), 
Styliolina  fissurella,  Tentaculites  gracilistriatus  (also  in  the  Marcellus),  Orthoceras  subu- 
latum  (also  Marcellus),  Goniatites  complanatus  (also  Upper  Ham.  and  Portage),  G.  dis- 
coideus  (Marc.,  Ham.  also),  G.  intumescens  (  =  G.  Patersoni}  (also Portage  and  Chemung). 

Portage  group. — Amboccelia  umbonata,  Grammysia  subarcuata,  Lunulicardium 
fragile,  L.  acutirostrum,  L.  ornatum,  Cardiola  speciosa,  Styliolina  fissu rella,  Bellerophon 
natator,  Coleolus  acicula,  Tentaculites  gracilistriatus,  Orthoceras  pacator,  Goniatites 
complanatus,  G.  intumescens,  G.  bicostatus,  G.  sinuosus. 

Ithaca  beds  (noted  for  the  number  of  Brachiopods) .  —  Lingula  spatulata,  Atrypa 
reticularis,  Spirifer  mesacostalis  and  S.  mesastrialis,  Cryptonella  eudora,  Stropheodonta 
mucronata,  Ehynchonella  pugnus,  R.  eximia,  Productella  speciosa,  Leiorhynchus  mesa- 
costale,  Orthis  impressa,  Chonetes  setigerus,  C.  scitulus,  Crania  ;  Lunulicardium  fragile, 
Schizodus  quadrangularis,  Palceoneilo  filosa,  species  of  Leptodesrna  and  Aviculopecten, 
Grammysia  subarcuata,  Tentaculites  spiculus,  Orthoceras  bebryx,  0.  fulgidum.  Spathio- 
caris  Emersoni  Clarke,  of  the  Portage,  is  described  and  figured  in  Am.  Jour.  Sc.,  xxiii., 
1882.  The  Palceopalcemon  was  first  described  by  Whitfield,  in  Am.  Jour.  Sc.,  xix.,  1880. 

The  Naples  beds,  in  the  Portage,  containing  the  Clymenia  (Fig.  949),  have  afforded 
also,  according  to  J.  M.  Clarke  (1891,  '92),  Palceoniscus  Dzvonicus  Clarke,  Acanthodes 


PALEOZOIC   TIME  —  DEVONIAN.  621 

priscusCl,  Conodonts,  Echinocaris  Whitjieldi  CL,  E.?  Beecheri  Cl.,  Spathiocaris  Emersoni 
Cl.,  species  of  Entomis,  Goniatites  intumescens  Beyrich,  and  many  other  species  of  the 
genus,  Orthoceras  pacator  Hall,  and  other  species  of  0.,  species  of  Bactrites,  Bactrites? 
acicula,  Hyolithes,  Tentaculites  gracilistriatus,  Styliolina  fissurella  Hall,  species  of 
Macrocheilus,  Platystoma,  Pleurotomaria,  Loxonema,  Bellerophon,  Leptodesma,  Leiopteria, 
Grammysia, Macrodon, Nucula,  Ungulina,  Lunulicardium,  Cardiola  (Cardiola  retrostriata 
abundant),  Pholadella,  Lingula,  Chonetes,  Aulopora,  Melocrinus  Clarki  Williams,  also 
species  of  fossil  wood.  The  Styliolina  limestone,  in  the  Genesee  shale  below,  contains  the 
first  representatives  of  the  Naples,  or  G.  intumescens,  fauna ;  in  it,  Dawson  has  identified 
Dadoxylon  (Cordaites")  Clarki,  Cladoxylon  mirabile  Unger.  The  fauna  and  flora  are 
related  to  that  associated  with  Goniatites  intumescens  in  Europe.  (J.  M.  Clarke.) 

Chemung  beds  of  New  York  and  Pennsylvania.  —  Dictyophyton  tuberosum ;  Orthis 
Tioga,  0.  impressa,  Stropheodonta  Cayuta,  Productella  lachrymosa,  P.  hirsuta, 
Rhynchonella  contracta,  Leiorhynchus  sinuatum,  L.  mesacostale,  Spirifer  disjunctus, 
Ambocwlia  umbonata  var.  gregaria,  Athyris  Angelica;  Aviculopecten  duplicatus,  Ptennea 
Chemungensis,  Ptychopteria  Sao,  P.  falcata,  Leptodesma  spinigerum,  Goniophora  Che- 
mungensis, Schizodus  Chemungensis,  Grammysia  subarcuata,  G.  communis,  Sphenotus 
contractus,  Prorhynchus  nasutum ;  Tropidocaris  bicarinata,  Echinocaris  socialis.  For 
descriptions  of  Chemung  fossils  see  Pal.  N.  Y.,  vols.  iv.,  v.,  vii.,  viii.  (C.  E.  Beecher.) 

Lamellibranchs  of  the  Middle  and  Upper  Devonian.  — The  total  number  of  species  of 
Lamellibranchs  described  and  figured  by  Hall  in  vol.  v.  of  the  Palaeontology  of  New  York 
is  458 ;  and  of  these  195  occur  in  the  Hamilton  beds,  and  263  in  the  Chemung.  The 
principal  genera  to  which  they  are  referred,  and  the  number  of  species  in  each,  are  as 
follows  —  H.  signifying  Hamilton,  and  C.,  Chemung :  — 

Actinopteria  (H.  7,  C.  10),  Aviculopecten  (H.  13,  C.  16),  Conocardium  (H.  4,  C.  2), 
Cypricardinia  (H.  2,  C.  1),  Edmondia  (H.  0,  C.  7),  Glossites  (H.  1,  C.  7),  Goniophora 
(H.  7,  C.  4),  Grammysia  (H.  15,-C.  9),  Leda  (H.  4,  C.  0),  Leiopteria  (H.  12,  C.  3),  Lep- 
todesma (H.  2,  C.  55),  Lunulicardium  (H.  7,  C.  6),  Microdon  (H.  4,  C.  2),  Modiomorpha 
(H.  10,  C.  7),  Mytilarca  (H.  2,  C.  8),  Nucula  (H.  9,  C.  5),  Nuculites  (H.  5,  C.  0),  Ortho- 
nota  (H.  4,  C.  1),  Palceanatina  (H.  0,  C.  4),  Pal&oneilo  (H.  10,  C.  10),  Panenka  (H.  12,  C.  3), 
Paracyclas  (H.  4,  C.  5),  Prorhynchus  (H.  0,  C.  3),  Ptennea  (H.  1,  C.  10),  Ptychopteria 
(H.  0,  C.  22),  Schizodus  (H.  3,  C.  8),  Sphenotus  (H.  5,  C.  5). 

E.  D.  Cope  has  announced  (1892),  from  the  bed  containing  Fish  remains,  of  Chemung 
age,  in  Mansfield,  Tioga  County,  Pa.,  besides  Holoptychius  Americanus,  the  species  Bothrio- 
lepis  nitida  Leidy,  Holonema  rugosum  Clayp.,  Ganorhynchus  oblongum  Cope,  Holoptychius 
giganteus  Ag. ;  in  Leroy,  Bradford  County,  Pa.,  the  bed  probably  Chemung,  H.  rugosus, 
H.  horridus  Cope,  H.  filosus  Cope ;  at  a  neighboring  locality,  Bothriolepis  minor  Newb., 
Coccosteus  macromus  Cope,  and  fragments  of  Osteolepisor  Megalichthys.  Phaneropleuron 
curtum  of  Whiteaves  (Fig.  969)  has  been  made  by  Traquair  into  a  new  genus,  named 
Scaumenacia,  on  the  basis  of  a  slight  difference,  in  the  dorsal  or  dorso-caudal  fin, 
between  it  and  the  original  Phaneropleuron  of  Huxley.  Plates  of  the  large  pterichthyoid 
fish,  Holonema  rugosum,  have  been  found  in  the  red  sandstones  of  the  Oneonta  group, 
near  Oxford,  N.Y.  (See  Proc.  A.  A.  A.  S.,  vol.  39,  1890,  page  337.  Also,  Am.  Geol,  vol. 
vi.,  page  226.) 

The  minute  teeth,  long  of  doubtful  ownership,  called  Conodonts,  now  regarded  as  the 
teeth  of  Annelids,  occur  of  several  species  in  the  Genesee  shales  of  Erie  County,  N.Y., 
at  North  Evans,  including  the  following  described  by  Hinde  (Q.  J.  G.  Soc.,  1877): 
Prioniodus  angulatus,  P.  acicularis,  P.  armatus,  P.  spicatus,  P.  erraticus,  Polygnathus 
dubius,  P.  nasutus,  P.  princeps,  P.  palmatus,  P.  punctatus.  A  plate  is  devoted  to  figures 
of  Conodonts  (PI.  57),  in  Ohio  Pal.,  ii.,  1875. 

Additional  Devonian  plants.  —  The  following  are  some  of  the  species  of  St.  John, 
New  Brunswick ;  those  that  occur  also  at  Gasp6  are  marked  with  an  asterisk,  and  those 
also  in  New  York  or  farther  West,  with  a  dagger. 


622  HISTORICAL   GEOLOGY. 

Psilophyton pri nceps  Dn.*t(Fig.  854,  page  583),  Lepidodendron  Gaspianum  Dn.,(Fig. 
855),  Sigillaria  palpebra  Dn.,  Stigmaria  perlata  Dn.,  Cordaites  Robbii  t  (Fig.  896),  Archce- 
opteris  Jacksoni  (Figs.  898,  899),  Neuropteris  polymorpha  Dn.  (Fig.  897),  N.  Dawsoni 
Hartt  (leaflet  over  six  inches  long),  jSphenopteris  Hitchcockiana  Dn.,  S.  Hceninghausi 
Brngt.,  S.  Hartti  Dn.,  Callipteris  pilosa  Dn.,  Hymenophyllites  Gersdorfi  Gopp.,  H. 
obtusilobus  Gopp.,  Alethopteris  discrepans  Dn.,  Pecopteris  preciosa  Hartt,  species  of 
Trichomanites,  Calamites  radiatus  Gopp.  (Fig.  900),  C.  cannceformis  Schlotheim,  Astero- 
phyllites  acicularis  Dn.,  A.  latifolius  Dn.  (Fig.  901),  Sphenophyllum  antiquum  Dn.  ; 
Dadoxylon  Ouangondianum  Dn.,  besides  fruits  of  Gymnosperms,  of  the  genera  Cardio- 
carpus  and  Trigonocarpus. 

A  Gymnosperm  fossil  wood,  from  Schoharie  County,  N.Y.,  has  been  named  Or- 
moxylon  Erianum  by  Dawson.  At  Perry,  Me.,  occur  Lepidodendron  Gaspianum  Dn., 
Leptophlceum  rhombicum  Dn.,  Archceopteris  Jacksoni  Dn.,  A.  Halliana,  A.  Rogersi 
Dn.,  A.  (Cyclopteris)  Browni  Dn.,  Caulopteris  Lockwoodi  Dn.,  Anarthrocanna  Perry  ana 
Dn.,  Stigmaria  pusilla  Dn.,  and  others,  there  being  very  few  of  the  St.  John  species. 
Some  species  are  the  same  that  occur  in  Subcarboniferous  beds.  See,  for  descriptions  of 
plants,  in  addition  to  Dawson's  publications,  also  C.  F.  Hartt  in  Bailey's  New  Brunswick 
Geol.  Bep.,  1865 ;  Lesquereux,  Report  on  Goal  Flora  of  Pennsylvania,  and  another  on 
Indiana;  Newberry's  Ohio  Reports,  and  other  publications,  etc. 

FOREIGN. 

The  Devonian  beds  in  the  British  Isles  comprise  the  Old  Eed  sandstone 
of  Scotland;  the  same  in  southeastern  Wales  and  the  adjoining  region  of 
Herefordshire  in  England,  and  of  some  parts  of  Ireland ;  and  areas  of  slates 
and  limestone  in  Devon  and  Cornwall,  or  southeastern  England.  The  fossil- 
iferous  Devon  areas  suggested  the  name  for  the  beds. 

The  more  northern  of  the  Scottish  areas  (a)  stretches  in  a  south- 
southwest  direction,  from  the  Shetland  and  Orkney  Islands,  along  the  west 
coast  of  Scotland  into  Loch  Ness ;  it  has  for  part  of  its  western  boundary 
the  northern  Highland  Archaean  region  of  Scotland  —  along  which  must 
have  run  a  western  shore-line  in  the  Devonian  sea.  (b)  Nearly  parallel 
with  this  northern  area,  another  crosses  central  Scotland  from  Stoneham  to 
the  Firth  of  Clyde ;  and  farther  south,  beyond  a  Carboniferous  belt,  is  still 
another  interrupted  line ;  and  this  central  trough  of  chiefly  Devonian  .and 
Carboniferous  rocks,  about  50  miles  wide,  is  in  the  line  of  the  area  of  Car- 
boniferous beds  (mostly  Subcarboniferous),  and  outcrops  of  Devonian,  which 
occur  over  western  Ireland,  (c)  A  third  area  is  .  that  of  eastern  Wales 
and  the  country  adjoining;  it  has  the  Siluro-Cambrian  region  of  Wales  as  its 
western  border ;  and  its  continuation  southwestward  embraces  the  Carbonif- 
erous area  of  South  Wales  ;  thence,  the  combined  Devonian  and  Carboniferous 
area  extends  over  Devon  and  Cornwall.  The  northeastward  and  eastward 
continuation  of  this  third  area  to  the  North  Sea  is  under  the  cover  of  Triassic 
and  later  rocks,  except  where  Carboniferous  beds  outcrop.  Borings  have 
been  supposed  to  prove  the  presence  of  Devonian  shales  and  sandstone  to 
the  eastward,  under  London,  at  a  depth  of  about  1000  feet,  Etheridge 
identifying  the  fossils  Spirifer  disjunctus,  Rhynclionella  cuboides  with  species 
of  Orthis,  Chonetes,  and  Edmondia. 


PALEOZOIC    TIME  —  DEVONIAN. 


623 


979. 


The  Old  Red  sandstone  is  the  rock  of  all  the  areas  excepting  that  of 
Devon  and  Cornwall.  It  consists  of  red,  purplish,  and  brown  sandstones, 
coarse  and  fine,  passing  to  a  conglomerate  and  also  to  bituminous  flags.  It 
shows  by  its  coarse  and  varying  features,  by  the  absence  of  fossiliferous  beds 
bearing  shells,  corals,  and  other  invertebrate  remains,  and  by  the  presence 
here  and  there  of  relics  of  Fishes  and  Eurypterids,  that  its  origin  was  much 
like  that  of  the  Catskill  Red  sandstone  of  eastern  America  —  a  roughly 
made  sea-border  formation,  in  waters  that  suffered  in  purity  from  the  contri- 
butions of  streams  from  the  bordering  hills.  The  American  Devonian  has 
abundant  life  beyond  the  Catskill  sandstone  area ;  and  in  the  British  seas 
the  beds  of  Devon  are  as  prolific  as  the  Chemung,  Hamilton,  and  Corniferous 
of  eastern  America. 

The  Old  Red  sandstone  of  Scotland  (called  Old  Red  in  contrast  with  the 
New  Red  or  Triassic)  is  reported  to  have  the  extraordinary  thickness  of 
10,000  to  16,000  feet.  It  is 
divided  into  an  Upper  and 
Lower  division,  by  a  plane 
of  unconf ormability  above  the 
level  of  the  Caithness  flags 
(A.  Geikie).  Besides  sand- 
stones the  central  basin  of 
Scotland  includes  a  great 
thickness  (6000  feet)  of  igne- 
ous rocks  —  f elsy te  and  f  el- 
syte  porphyry,  doleryte  and 
other  kinds ;  now  forming,  as 
Geikie  states,  chains  of  hills, 
as  in  the  Pentland,  Orchir  and 
Sidlaw  ranges.  They  occur 
interstratified  with  the  ordi- 
nary beds,  several  thousand 
feet  above  the  base  of  the 
Devonian,  and  indicate  a  long 
period  of  ejections.  The  ba- 
sins of  the  Cheviot  Hills  and 
of  Lome  also  had  their  vol- 
canic ejections. 

The  Old  Red  sandstone  is 
remarkable  for  its  Eurypterids. 
A  Pterygotus  is  represented  in 

Fig.  979,  P.  Anglicus,  which  has  a  length  of  six  feet — more  than  three 
times  that  of  any  Crustacean  now  living.  Other  common  genera  are 
Eurypterus  and  Stylonurus.  An  Ostracoid,  Estheria,  is  abundant  in  some 
places.  A  gigantic  Isopod  Crustacean,  the  Prcearcturus,  has  been  described 
by  Woodward  (1870)  from  the  Old  Red  sandstone  of  Herefordshire. 


EUBYPTERID.  —  Fig.  979,  Pterygotus  Anglicus ;  a,  eye; 
/,  appendages  ;  1  to  13,  numbering  of  segments. 


624 


HISTOKICAL   GEOLOGY. 


Modern  Isopods  are  seldom  over  two  inches  long.     The  basal  joint  of  a  leg 
of  the  Praearcturus  was  three  inches  long,  and  three  quarters  of  an  inch 


980-983. 
980. 


PLA.CODERMS.  —  Fig.  980,  Cephalaspis  Lyelli  (x|);  980  a,  same,  with  pectoral  fins  in  place;  980  6,  c,  scales; 
981,  Coccosteus  decipiens,  side  view;  981  a,  dorsal  plates;  982,  Pterichthys  Milleri  (x|) ;  983,  Pterichthys 
cornutus.  Figs.  980,  981,  Agassiz  ;  981  a,  983,  Traquair  ;  982,  Pander. 


PALEOZOIC   TIME  —  DEVONIAN. 


625 


through.  Two  species  of  Myriapods  have  been  described  from  the  lower  Old 
Red  sandstone  of  Forfarshire,  Scotland,  Kampecaris  Forfarensis  Page,  and 
Archidesmus  MacNicoli  Peach. 

The  Fishes  of  the  Old  Red  sandstone  have  come  mostly  from  bituminous 
flags  in  northern  Scotland  and  North  Wales,  and  include  species  of  the 
Placoderm  genera  Cephalaspis  (Fig.  980),  Pteraspis,  Cyathaspis,  Auchenaspis, 
Holaspis;  Aster  olepis,  Pterichtliys  (Figs.  982,  983),  Bothriolepis,  Coccosteus 
(Fig.  981);  also  the  Dipnoan  genera,  Dipterus,  Phaneropleuron ;  and  the  true 
Ganoids,  Holoptychius,  Glyptolepis,  Dendrodus,  Cheiracanthus.  The  Cephal- 
aspids  are  absent  from  the  Upper  Devonian  of  Scotland. 


984-985. 


984 


984  a. 


985  a 


GANOID.  —  Fig.  984,  Holoptychius  (x£) ;  984  a,  a  scale.    DIPNOAN.  —985,  Dipterus  macrolepidotus  (x  J) ;  985  a, 

a  scale. 

The  Devon  beds  have  an  estimated  thickness  of  10,000'  to  12,000'.  They  afford  a  large 
variety  of  Corals,  Brachiopods,  and  other  species,  a  number  of  them  related  to  those  of  the 
American  Devonian.1  The  Lower,  Middle,  and  Upper  divisions  are:  (l)the  LOWER  or 
LYNTON  group  of  sandy  slates  and  grits,  affording  Actinocrinus  tenuistriatus,  Favosites 
cervicornis,Orthisarcuata,  0.  granulosa,  Spirifer  canaliferus,  S.hystericus,  S.lcevicostatus, 
Streptorhynchus  umbraculum,  Chonetes  Hardrensis ;  (2)  the  MIDDLE  or  ILFRACOMBE  group 
of  slate  and  grits,  with  beds  of  limestone,  containing  several  species  of  Crinoids ;  many 
Corals,  including  Heliophyllum  Halli,  Cynthophyllum  c&spitosum,  species  of  Favosites, 
Acervidaria,  etc.;  Stromatopora  of  several  species ;  Atrypa  reticularis,  A.  Icevis,  A.aspera, 
Ehynchonella  cuboides,  Merista  plebeia,  Orthis  striatida,  Spirifer  curvatus,  S.  disjunctus, 
String ocephalus  Burtini,  Streptorhynchus  crenistria,  Strophomena  rhomboidalis,  Platy- 
ceras  vetustum,  species  of  Euomphalus,  Loxonema,  Murchisonia ;  Goniatites,  Orthoceras, 
Cyrtoceras ;  Tentaculites  scalans;  Phacops  latifrons,  P.  granulata,  and  also  species  of 
Bronteus,  Harpes  and  Ceraurus  •  (3)  UPPER,  including  Pickwell  Down  and  Pilton  beds, 

1  In  the  following  lists  of  foreign  species,  the  new  generic  names  of  Brachiopods,  recently 
introduced  by  Hall  and  Clarke  in  their  revision  of  the  subject,  are  not  inserted,  as  they  are  not 
yet  in  use  in  anv  foreign  work  on  geology  or  paleontology. 
DANA'S  MANUAL  —  40 


626  HISTORICAL   GEOLOGY. 

containing  many  Crinoids  and  Brachiopods :  Pentremites  ovalis,  Athyris  concentrtca, 
Spirifer  decussatus,  S.  Urii,  Orthis  plicata,  O.  parallela,  0.  interlineata,  Productus 
prcelongus,  Streptorhynchus  crenistria ;  with  several  species  of  Clymenia,  Goniatites, 
Orthoceras  •  also  Phacops  latifrons,  etc. 

Among  the  Devonian  plants  of  Ireland,  in  beds  that  contain  also  remains  of  Coccos- 
teus  and  Glyptolepis,.  there  are  Cyclopteris  Hibernica  Forbes,  Sphenopteris  Hookeri  Baily, 
S-  Humphriesiana,  Catamites  radiatus  Br.,  Lepidodendron  Veltheimanum  Sternb.,  Knor- 
ria  acicularis  Gopp.,  Cyclostigma  minutum  Haughton,  C.  Kiltorkense  Haughton,  and 
other  species.  The  whole  number  known  of  species  of  Fishes  from  the  Lower  Devonian 
of  Great  Britain,  as  stated  by  Etheridge  in  1885,  is  88,  4  species  of  Onchus  being  ex- 
cluded ;  in  the  Middle  Devonian,  2  ;  in  the  Upper,  28.  The  only  genera  common  to  the 
Lower  and  Upper  are  Pterichthys,  Asterolepis,  Holoptychius  and  Platygnathus.  Of  the  577 
species  in  the  fauna,  50  pass  up  into  the  Carboniferous. 

In  the  Ardennes,  on  the  borders  of  France  and  Belgium,  there  is  the  west  border  of  a 
broad  Devonian  area  which  crosses  the  Rhine  north  of  Mayence  with  bold  features  along  the 
river,  and  extends  to  Nassau  and  Westphalia.  The  Lower,  Middle,  and  Upper  divisions  are 
named(l)  the  Rhenan,  (2)  the  Eifelian,  and  (3)  the  Famennian.  In  the  region  of  the 
Ardennes  the  Lower  consists,  according  to  Gosselet,  of  (1)  the  Gedinnian,  about  2500'  thick, 
containing  Homalonotus,  Tentaculites,  Spirifer  Dumonti ;  (2)  the  Taunusian,  about  1800' 
thick,  with  Pleurodictyon,  Lcptcena  Murchisoni,  L.  laticosta ;  (3)  the  Coblenzian,  about 
8000'  thick,  with  Strophomena  depressa,  Grammysia  Hamiltonensis  (  =  bisulcata)  ;  and  at 
top,  Spirifer  cultrijugatus,  Calceola  sandalina  (the  latter,  perhaps,  Eifelian).  The  Middle 
or  Eifelian^  over  3000'  thick,  includes  the  Calceola  slates,  and  above  these  the  Givet  lime- 

986-987. 

987. 


CEPHALOPODS.  —  Fig.  986,  Clymenia  Sedgwicki ;  986  o,  dorsal  view  of  septa  ;  987,  Goniatites  retrorsus.    Fig. 

836,  D'Orbigny  ;  98T,  Vogt. 

stone  (Givetiari)  or  Stringocephalus  beds ;  the  former  containing  Phacops,  Sronteus,  Orthis 
striatula,  Productus  subaculeatus,  Pentamerus  galeatus ;  the  latter,  Stringocephalus 
JSurtini,  Heliolites  porosus,  etc.  The  Upper  or  Famennian,  over  2500',  consisting  of  the 
Frasnian  shales  and  limestone  below,  and  the  Famennian  shales  and  Sandstones  of 
Condros  above,  with  Atrypa  reticularis,  Orthis  striatula,  Spirifer  Verneuili  (S.  disjunctus*) , 
Clymenia,  Archceopteris  Hibernica,  Sphenopteris  Jlaccida.  The  Devonian  outcrops  also  to 
the  northwest  in  the  Boulonnais,  in  Brittany  -and  the  Vosges,  and  to  the  eastward,  in  the 
Harz  and  Thuringia. 


PALEOZOIC    TIME DEVONIAN. 


627 


In  the  Eifel,  the  three  divisions,  the  Bhenan,  Eifelian  and  Famennian  are  well 
developed.  The  Ehenan  contains  Dalmanites,  Phacops  latifrons,  Spirifer  cultrijugatus, 
etc.  The  Eifelian  consists  below  of  the  Calceola  beds,  with  C.  sandalina  and  Spirifer 
cultrijugatus,  and  above,  of  the  Stringocephalus  beds. 

The  Famennian,  or  Upper  Devonian,  consists  of  (1,  or  below)  the  Cuboides  shale  with 
dolomytic  beds,  containing  Ehynchonella  cuboides,  Spirifer  glaber,  S.  Verneuili,  S.  Urii, 
Atrypa  reticularis,  Athyris  concentrica,  Productus  subaculeatus,  Camarophoria  formosa; 
(2)  Goniatite  bed,  with  Goniatites  retrorsus  (Fig.  987) ,  G.  primordialis,  Orthoceras  sub- 
flexuosum,  Bactrites  gracilis,  Pleurotomaria  turbinea,  Cardiola  retrostriala,  Cypridina 
serrato-striata ;  (3)  the  Cypridina  shale,  with  C.  serrato-striata  (Fig.  989)  and  Posido- 
nomya  venusta. 

Similar  subdivisions  occur  in  Westphalia  and  Nassau,  the  Fichtelgebirge,  and  other  areas 
of  Germany.  In  the  Thuringian  Forest  and  the  Fichtelgebirge,  the  Upper  Devonian  con- 
tains in  the  Clymenia  and  Orthoceratite  limestones,  Clymenia  Icevigata,  C.  undulata, 


988-989. 


989  a. 


CBTTSTACEANS.  —  Fig.  988,  Arges  annatus  of  the  Eifel ;  989,  slate,  from  Weilburg,  containing  Cypridina  serrato- 
striata,  natural  size  ;  989  a,  same  enlarged.    Vogt. 

Goniatites  retrorsus,  G.  intumescens,  Orthoceras  interruptnm,  Gomphoceras,  Cyrtoceras, 
Athyris  concentrica,  Ehynchonella  cuboides,  Bronteus  grandis,  and  other  species,  besides 
remains  of  Calamites,  Lepidodendron,  Stigmaria,  Aporoxylon. 

In  Russia  (the  Continental  Interior  of  Europe)  the  Devonian  beds  cover  a  large  area, 
and  are  nearly  horizontal.  The  western  areas  include  only  Middle  and  Upper  Devonian. 
Below  are  limestone  and  red  marls;  and  above,  limestone  and  shales  with  some  sand- 
stones, having  partly  the  character  of  the  Old  Red  sandstone  of  Scotland,  and  like  that 
containing,  says  Murchison,  remains,  of  Fishes  as  almost  the  only  fossils.  Pander  has 
described  species  of  Coccosteus,  Osteolepis,  Dipterus,  and  Diplopterus  from  the  Middle,  and 
Holoptychiits  nobilissimus,  Pterichthys  major,  and  Asterolepis  from  the  Upper.  The 
Lower,  Middle,  and  Upper  Devonian  occur  in  the  Urals,  through  nearly  the  whole  length 
of  the  range. 

In  South  America,  Devonian  beds  occur  over  the  Highlands  of  eastern  Bolivia,  —  Lower 
and  Middle  Devonian  (D'Orbigny,  M.  D.  Forbes,  Steinmann);  in  the  region  of  Lake 
Titicaca,  Lower  Devonian  (Agassiz  and  Garman)  ;  in  Brazil,  in  the  province  of  Para, 
north  and  south  of  the  Amazon,  200  to  400  miles  from  the  coast,  Lower,  Middle,  and 
Upper  Devonian  (O.  A.  Derby,  and  others) ;  in  the  Falkland  Islands  (Darwin).  In  the  vicin- 
ity of  the  Amazon,  on  its  north  rise,  Hamilton  beds  include  species  of  the  genera  Vitulina, 
Tropidoleptus,  JRetzia,  and  others,  described  by  Rathbun,  and  one  variety  of  Discina 
Lodensis  Hall.  Ulrich  reports,  from  eastern  Bolivia,  species  of  the  genera  Leptoccelia, 
Vitulina,  and  Tropidoleptus,  besides  others,  and  states  that  the  first  of  these  three  genera 
occurs  also  in  the  Devonian  of  the  Falkland  Islands  and  of  South  Africa,  and  that  the  second 
is  also  South  African.  (For  remarks  on  the  distribution  of  these  and  other  genera,  see 


628  HISTOKICAL   GEOLOGY. 

Address  of  H.  S.  Williams,  Am.  Assoc.,  1892.)  The  Ida  shales  of  Bolivia  are  Corniferoub, 
and  the  Huamampampa  sandstone  is  Hamilton. 

In  southwestern  China  Richthofen  obtained  from  the  Devonian  beds  the  wide-range 
fossils  Pentamerus  galeatus,  Atrypa  reticularis  var.  desquamata,  Merista  plebeia,  Spirifer 
Verneuili  (  =  disjunctus),  Orthis  striatula,  Productus  subaculeatus,  titrophalosia  pro- 
ductoides,  Ehynchonella  cuboides,  E.  pugnus,  Aulopora  tubiformis  (China,  iv.,  75). 

Australian  Devonian  beds  of  the  Itydal  District,  and  to  the  north  and  south  of  it,  have 
afforded  the  species  Cyathophyllum  Damnoniense,  Favosites  reticulatus,  F.  fibrosus, 
Heliolites  porosus,  Chonetes  Hardrensis,  Orthis  striatula,  Ehynchonella  pleurodon,  R. 
pugnus,  E.  cuboides,  Atrypa  reticularis,  Spirifer  Verneuili,  and  also  the  plant  Lepido- 
dendron  (W.  B.Clarke,  On.  Sedim.  Form.  N.S.W.,  4th  edit.,  1882).  The  Devonian 
occurs  also  in  Queensland,  and  near  Bathurst  in  Tasmania. 


GEOLOGICAL  AND   GEOGRAPHICAL  PROGRESS  DURING  THE  DEVONIAN. 

AMERICAN. 

In  the  Devonian  era,  as  in  the  Upper  Silurian,  the  great  rock  formations 
that  are  open  to  investigation  were  the  work  of  the  Interior  Continental 
waters.  Progress  was  still,  in  the  main,  endogenous,  or  within  the  Interior 
Sea.  No  Paleozoic  rocks,  later  than  the  Lower  Silurian,  have  yet  been  re- 
ported from  the  Atlantic  border,  along  the  coast  region  of  New  Jersey  and 
the  states  southward. 

The  confined  condition  of  the  Eastern  Interior  Sea,  or  Bay,  had,  with  the 
progress  of  the  era,  an  increasingly  profound  influence  on  the  nature  of  the 
successive  formations.  The  bay  had  its  northwest  passage  over  Michigan  open, 
but  not  the  northeast  passage  to  Canada.  The  Devonian,  as  has  been  shown, 
began,  like  the  Silurian,  with  beach  and  sea-border  deposition,  sparingly 
fossiliferous,  marking  off  the  coast-line  on  the  north  and  northeast,  and  an 
off-shore  bay-like  formation — the  Schoharie — bearing  evidence  of  abundant 
life.  But  these  rocks  had  acquired  little  thickness  before  the  commencement 
of  the  Corniferous  limestone  formation,  or  rock  coral-reef,  when  clearer 
waters,  with  growing  Corals,  Crinoids,  Trilobites,  and  other  species  of  the 
purer  seas,  were  in  great  profusion,  and  spread  from  near  the  Hudson  to 
Missouri  and  Iowa.  The  waters  reached  north  to  Mackinac,  the  head  of  a 
great  Michigan  bay  of  the  era,  but  appear  not  to  have  covered  northern 
Illinois  or  Wisconsin.  Moreover,  the  Canada  and  New  England  seas  also 
had  their  coral  reefs. 

It  is  remarkable  that  this  coral-reef  rock  is  not  recognized  over  Pennsyl- 
vania and  to  the  southwest.  The  Eastern  Interior  Sea  had  open  connection 
with  the  Central  Interior  by  the  northwest.  As  to  the  southern  entrance, 
nothing  is  known. 

At  the  close  of  the  Early  Devonian  the  evidences  of  clear  seas  —  the 
Corals  and  Crinoids,  with  most  of  the  attendant  life  —  disappear,  migrating  no 
one  knows  whither.  Depositions  of  silt,  mud,  and  sand  prevail  to  the  east- 
ward with  various  alternations  and  but  thin  intercalations  of  limestone ;  and 
so  it  was  also  over  the  Central  Interior,  except  sparingly  in  the  Hamilton 


PALEOZOIC   TIME — DEVONIAN.  629 

period.  With  the  variations  in  the  fineness,  or  other  characteristics  of  the 
beds,  as  H.  S.  Williams  has  illustrated,  the  species  vary.  The  fine  shales  of 
the  Marcellus  and  Genesee  shales  have  few  and  small  species,  owing  to 
some  unfavorable  conditions ;  and,  in  part,  the  species  are  repeated  in  each 
later  return  of  the  beds  to  fine  shales.  With  the  coarser  sand-beds  of  the 
Hamilton  and  Chemung,  life  abounds;  but  Brachiopods  and  Lamellibranchs 
predominate,  especially  in  the  latter,  where  Trilobites  fail  completely.  With 
beds  of  intermediate  character,  as  those  of  the  Portage,  life  is  much  less 
abundant  than  in  the  Chemung  —  except  at  one  time  of  change  to  beds 
allied  to  those  of  the  Hamilton  and  Chemung  (the  Ithaca  beds),  when  the 
life  takes  a  character  resembling  that  of  the  latter  period.  A  thin  lime- 
stone stratum  in  some  cases  indicates  by  the  species  an  approximation  again 
to  the  clearer  waters  of  the  Corniferous.  There  are  thus  alternations  in 
living  species  correlatively  with  alternations  in  kinds  of  deposits.  The 
species  evidently  migrated  in  the  direction  in  which  the  conditions  were 
favorable  to  them.  The  faunas  of  each  stratum  are  not  strictly  faunas  of 
epochs  or  periods  of  time,  but  local  topographical  faunas.  After  the  Cor- 
niferous period,  Corals,  Crinoids,  and  Trilobites  still  flourished  somewhere, 
as  before ;  but  they  are  absent  from  the  Central  Interior  until  the  Carbo- 
niferous age  opens. 

The  condition  producing  the  Genesee  shale  in  New  York  appears  to  have 
spread  westward  over  Ohio,  and  to  have  invaded  the  Central  Interior  through 
Michigan, Indiana, the  southern  half  of  Illinois,  and  southward  to  Tennessee; 
and  to  have  continued  to  prevail  over  this  great  region  through  the  remainder 
of  the  Devonian  era  with  but  little  change.  The  area  was  mud-making,  with 
more  evidence  of  fresh-water  or  brackish-water  life  than  of  marine  conditions, 
and  it  probably  had  its  extensive  shallow  lagoons  and  bayous  in  which  lived 
the  great  Ganoids  and  Eurypterids.  During  the  Later  Devonian,  in  the 
Eastern  Interior  Sea,  the  Catskill  sandstone  to  the  northeast  —  a  shore  and 
off-shore  formation  of  the  Interior  Continental  Sea  —  reached  a  thickness  of 
3000  to  7545  feet  (I.  C.  White),  because  it  lay  within  the  range  of  the  Appa- 
lachian geosyncline. 

If  the  condition  of  the  Atlantic  border,  its  sounds  and  bays,  with  their 
varying  depths  and  fortunes,  and  of  off-shore  deeper  waters  and  depositions 
and  fresh-water  inlets,  be  taken  as  a  type  of  the  conditions  and  depositions 
that  existed  in  several  successions  within  the  Eastern  Interior  Sea,  no 
difficulty  will  be  found  in  finding  a  reason  for  all  the  variations  in  wave 
action,  in  tidal  and  current  action,  in  depth,  in  purity  of  waters  —  ranging 
off  to  over-fresh  or  over-salt  conditions,  which  may  be  needed  to  explain 
the  geological  and  biological  facts  of  the  Middle  and  Later  Devonian. 

The  effects  of  tidal  currents  appear  to  be  marked  in  the  Chemung  beds 
of  western  New  York  and  Pennsylvania,  and  eastern  Ohio.  The  strata  of 
coarse  conglomerates  occurring  among  the  sand-beds  appear  to  be  due  to  their 
action.  The  tidal  waters,  which,  in  their  rounds,  converged  from  the  south 
and  west  toward  the  head  of  the  Eastern  Interior  Bay,  with  increasing  height 


630  HISTORICAL   GEOLOGY. 

as  they  advanced,  may  have  made  their  ebb  or  their  flow  over  this  more 
western  part  of  the  bay-like  channel ;  and,  by  their  rapid  movement,  have 
produced  the  assorting  of  the  gravel  and  the  accumulations  of  large  stones 
or  pebbles;  and  they  may  also,  by  some  variation  in  their  route,  as  time 
passed,  have  made  pebble  deposits  locally  at  different  levels.  Such  rapid 
tidal  flows,  causing  the  stones  in  shallow  waters  to  slip  over  one  another 
with  each  return  of  the  current,  would  tend  to  make  them  flat,  as  in  the 
Panama  conglomerate,  and  not  round  as  in  ordinary  round-pebble  con- 
glomerates, the  latter  being  work  of  plunging  waves  along  a  beach  and  of 
strong  currents. 

BIOLOGICAL    PROGRESS. 

The  progress  of  the  systems  of  life  through  the  Devonian  era  was  con- 
tinued into  and  through  the  following  era  without  any  abrupt  transition, 
and  the  review  of  the  subject  is  given  for  both  eras  after  the  account  of  the 
Carbonic  era. 

UPTURNING  OR  MOUNTAIN-MAKING  AT  THE   CLOSE   OF   THE 

DEVONIAN. 

Through  nearly  all  of  North  America,  where  Devonian  and  Carboniferous 
rocks  occur  together,  the  two  formations  pass  into  one  another  continuously, 
as  if  one  in  series.  But  in  eastern  Canada  at  Gaspe,  in  Maine,  and  in  Nova 
Scotia,  and  at  Perry  in  southern  New  Brunswick,  as  reported  by  Dawson  and 
Logan,  there  was  an  upturning  of  the  Devonian  and  inferior  beds,  so  that 
the  overlying  Carboniferous  rests  upon  them  unconformably.  Dawson 
makes  the  unconformability  general  for  the  Acadian  Provinces. 

The  upturning  and  crystallization  of  the  Devonian  and  Upper  Silurian 
beds  of  the  Connecticut  valley,  as  well  as  of  those  of  Lake  Memphremagog 
and  the  St.  Lawrence  valley,  may  have  been  a  part  of  the  events  of  this 
epoch.  But  it  is  equally  possible  and  probable  that  the  upturning  took 
place  at  the  close  of  Paleozoic  time. 

In  Great  Britain,  Kussia,  and  Bohemia,  some  evidences  of  upturning 
between  the  Devonian  and  Carboniferous  have  been  observed,  and  not  in 
central  and  southern  France.  But  all  these  cases  are  small  exceptions  to 
the  general  fact  that  the  Lower  Carboniferous  and  the  underlying  rocks 
are  conformable  almost  the  whole  world  over.  The  epoch  of  transition  was 
not  an  epoch  of  general  disturbance.  There  were  extensive  oscillations  of 
level;  but  for  the  most  part  they  involved  no  violent  upturnings.  The 
following  era  opens  with  a  period  of  marine  formations  ;  and  the  beds  accu- 
mulated, in  most  regions  where  they  occur,  are  a  direct  continuation  of  the 
deposits  of  the  Devonian. 


PALEOZOIC    TIME  —  CARBONIC. 


CARBONIC   ERA. 

SYNONYMY. — Carboniferous  and  Permian  periods,  Lyell  (Elements  of  Geol.,  1839), 
and  other  British  geologists,  German  geologists,  and  D'Orbigny,  1851,  in  France.  Carbo- 
niferous age  (Permian  included),  Dana,  Man.  Geol.,  1st  edit.,  1863,  2d  edit.,  1874,  3d  edit., 
1880;  Le  Conte,  Elements  of  Geol.,  1877,  and  later;  A.  Winchell,  Geol.  Studies,  1886. 
Permo-Carboniferous,  Dawson,  Suppl.  Acad.  Geol.,  1878.  Carboniferous,  Permo-Carbo- 
niferous,  W.  M.  Fontaine  and  I.  C.  White,  on  Permian  Plants  of  W.  Va.  and  Penn.,  1880. 
Permo-Carbonifere,  Lapparent,  Tr.  de  GeoL,  1883.  Permo-Carbonic,  Portuguese  Commit- 
tee Internal.  Congr.  Geol.,  1886.  Carbonic  (Permic  or  Permian  included),  E.  Renevier, 
Tableau  des  Terrains  Sedimentaires,  1874,  Int.  Congr.  Geol.,  1886. 

This  first  great  coal-making  era  in  the  world's  history  commenced,  both 
in  Europe  and  America,  with  an  extensive  submergence  of  the  land  and  a 
consequent  formation  of  marine  terranes  of  great  thickness  over  parts  of 
the  continental  areas.  It  passed  its  culmination  during  a  long  period  of  gen- 
tle oscillations  in  the  surface,  causing  successive,  more  or  less  wide,  emer- 
gencies and  submergencies,  the  former  favoring  the  growth  of  boundless 
forests  and  jungles,  the  latter  burying  the  vegetable  debris  arid  other  terres- 
trial accumulations  beneath  marine  or  fresh-water  deposits.  It  declined 
through  a  period  in  which  the  Carboniferous  marshes  gradually  disappeared, 
as  the  sea  regained  its  place  over  the  land ;  but  again  to  retreat,  as  Paleozoic 
time  ended,  and  the  making  of  the  Appalachian  Mountains  —  the  next  great 
event  in  North  American  history  —  was  commenced. 

The  occurrence  in  Europe  of  alternating  conditions  like  those  of  eastern 
North  America  is  part  of  the  evidence  that  the  coal  formations  of  the  two 
continents  were  essentially  cotemporaneous  in  origin.  Facts  from  the  fossils 
sustain  this  conclusion.  They  lead  to  the  following  subdivisions  of  the 
era:  — 

SUBDIVISIONS  OF  THE  CARBONIC  ERA. 

3.  PERMIAN  PERIOD.  —  Part  of  New  Bed  Sandstone  or  Poikilitic  group  of 

J.  Phillips  (the  rest  Trias). 
Lower  New  Ked  Sandstone  or  Magnesian  limestone  group,  Lyell,  El.  GeoL, 

2d  edit,  1841. 
PERMIAN,  Murchison,  Leonh.  u.  Bronn'sJahrb.,  1841,  Phil.  Mag.,  xix.  417 ; 

Murchison,  de  Verneuil,  and  Keyserling,  Geol.  Russ.,  1845 ;  Lyell,  El. 

Geol,  3d  edit.,  1851.     Permisches  System,  Geinitz,  1848,  1858. 
Part  of  Mercian  (the  rest  Triassic  and  Jurassic),  T.  McK.  Hughes,  Proc. 

Cambr.  Phil.  Soc.,  iii.  24. 
Dyas,  J.  Marcou,  Dyas  et  Trias,  Gen&ve,  1859,  H.  B.  Geinitz,  1861,  1862 

(Murchison's  Permian  having  been  made  by  him  to  include  a  small  part 

of  the  Trias  in  Germany,  though  not  of  that  in  England). 

2.  CARBONIFEROUS  PERIOD.  —  The  Coal-measures,  with  the  underlying  Mill- 
stone Grit. 

Carboniferous  period  of  Lyell,  Murchison,  and  other  English  geologists 
(the  Mountain  limestone  commonly  included). 


632  HISTORICAL   GEOLOGY. 

Carboniferien,  Calcaire  Carbonifere  et  Terrain  Houiller,  E.  de  Beaumont, 

D'Orbigny. 

Carboniferous  Period,  Dana,  Man.  GeoL,  1st.  edit.,  1863  and  later. 
Pennsylvania!!,  H.  S.  Williams,  U.  S.  GeoL  Surv.,  Bull.  80,  1891. 

1.    SUBCARBONIFEROUS  PERIOD.  — Mountain,  or  Carboniferous,  limestone,  the 

lower  division  of  the  Carboniferous  system,  Murchison,  Lyell,  etc. 
Lower  Carboniferous.     Lower  part  of  the  Systeme  Carboniferien,  Calcaire 

Carbonifere,  D'Orbigny,  Lapparent.     Bergkalk,  Untercarbon. 
Subcarboniferous,  D.  D.  Owen,  Rep.  Geol.  Wisconsin,  Iowa,  and  Minnesota, 

1852 ;  Dana,  Man.  GeoL,  1863  and  in  subsequent  editions. 
Subcarbon,  Steinmann  and  Doderlein,  Elem.  d.  Pal.,  1888. 
Mississippian,  H.  S.  Williams,   U.  S.  GeoL  Surv.,  Bull.  80,  Correlation  of 

the  Devonian  and  Carboniferous,  1891. 
Eocarboniferous,  H.  S.  Williams,  Journ.  GeoL,  Chicago,  1894. 


The  comprising  of  the  Permian  period  and  the  Carboniferous  in  a 
common  era  is  questioned  by  some  geologists.  In  North  America  the 
Permian  beds  are  a  direct  continuation  of  the  Carboniferous,  and  from  the 
general  absence  of  vertebrate  and  invertebrate  fossils  they  are  scarcely 
separable  in  most  regions  except  through  a  careful  study  of  the  fossil  plants. 
Such  a  study,  made  for  Pennsylvania  and  Virginia  in  part  by  Lesquereux, 
but  with  completeness  by  Fontaine  and  I.  C.  White,  has  afforded  satisfactory 
proof,  as  they  state,  that  the  Permian  is  fully  represented  in  eastern  America, 
and  that  the  period  is  here  only  a  continuation  of,  or  a  closing  addition  to, 
the  Carboniferous  period.  There  is  the  same  evidence  from  the  plants  and 
also  from  the  nearly  universal  conformity  in  the  stratification  of  the  two 
formations  as  to  the  close  relations  of  the  two  periods  in  Europe,  and  this 
is  sustained  paleontologically,  as  these  authors  remark,  "  by  the  investiga- 
tions of  Weiss,  Grand'  Eury,  and  others." 

The  other  continents  were  not  so  well  supplied  with  coal-making  areas  as 
North  America  and  Europe.  South  America  has  the  rocks  over  part  of  its 
great  interior,  with  little  of  the  coal,  and  is  in  this  respect  like  the  western 
half  of  North  America. 

Asia  has  much  coal  of  the  Carboniferous  period  in  northern  China.  But 
in  India,  or  southern  Asia,  the  chief  coal  era  began  in  the  Permian  and  con- 
tinued into  the  Triassic ;  and  the  same  was  true  for  southwestern  Africa,  and 
the  southern  continent,  Australia.  The  fact  that  one  of  the  world's  hemi- 
spheres was  not  concurrent  in  its  geological  movements  with  the  other, 
mentioned  on  page  406,  is  here  exemplified.  It  has  afforded  some  strength 
to  the  argument  that  the  Permian  period  should  not  be  united  to  the 
Carboniferous.  But  the  distinctions  that  exist  can  be  recognized  and  ap- 
preciated for  lands  about  the  Indian  Ocean,  without  interfering  with  the 
chronological  subdivisions  which  best  accord  with  the  facts  in  the  others 
where  these  subdivisions  were  first  laid  down. 


PALEOZOIC   TIME  —  CARBONIC. 


633 


NORTH    AMERICA. 
TOPOGRAPHY. 

The  topography  of  the  continent  at  the  commencement  of  this  era  is 
approximately  represented  on  the  accompanying  map,  Fig.  990,  on  which  the 
dotted  lines  over  the  surface,  marking  river  courses,  outlines  of  lakes,  etc., 
are  to  be  taken  only  as  indicating  positions.  The  chief  change  since  the 
commencement  of  the  Upper  Silurian  (page  536)  is  in  the  eastern  portion  — 
or  that  of  the  Eastern  Interior  or  Great  Northeast  Bay,  which,  at  the  opening 
of  the  coal  era,  was  a  complete  bay  in  outline,  reaching  northeastward  to  the 

990. 


Map  of  part  of  North  America  at  the  commencement  of  the  Carbonic  era. 

boundary  of  northeast  Pennsylvania.  It  was  in  fact  a  double-headed  bay,  a 
branch  passing  northwestward  from  the  Pennsylvania  portion  or  bay  (P),  over 
Michigan,  and  making  thereby  a  Michigan  Bay  ( M) .  The  Cincinnati  Island 
(C)  became  part  of  the  mainland,  while  the  Tennessee  was  submerged.  In 
addition,  the  Connecticut  valley  trough  and  the  St.  Lawrence  valley  trough 
were  probably  above  the  reach  of  salt  water,  or,  at  least,  were  not  subsiding 
troughs,  for  no  Carboniferous  rocks  occur  within  them;  they  were  probably 
the  courses  of  fresh-water  streams.  But  the  Gaspe- Worcester  trough  must 
have  been  an  open  channel,  southward  to  Worcester  at  least,  and  the  Acadian 
trough,  from  western  Newfoundland  to  Narragansett  Bay,  was  a  still  larger 


634 


HISTORICAL   GEOLOGY. 


channel,  in  coal-making  times,  as  is  proved  by  the  coal-beds  in  Newfound- 
land, Nova  Scotia,  and  New  Brunswick  on  the  north,  and  in  Ehode  Island 
and  a  part  of  eastern  Massachusetts  on  the  south. 

The  Western  Interior,  Rocky  Mountain,  and  Pacific  Border  regions  of  the 
continent  were  largely  covered  by  the  Mediterranean  Continental  Sea,  so  that 
the  western  part  of  the  map  for  the  Upper  Silurian  era,  on  page  536,  answers 
sufficiently  well  for  this  portion  of  the  continent  in  the  Carbonic  era. 


SUBDIVISIONS. 

PENNSYLVANIA. 


(      The     Upper     Barren 
3.  Permian  Period,     -j  ,  _ 

(  Measures. 


4.  Upper    Productive 
Measures. 

3.  Lower  Barren  Meas- 
ures. 

2.  Lower    Productive 
Measures. 

1.  Pottsville  Conglom- 
.  erate,  or  Millstone  Grit. 


MISSISSIPPI   BASIN. 

Permian  beds. 


2.  Carboniferous 
Period. 


1.  Subcarboniferous 
Period. 


2.  Mauch  Chunk  group 
of  Lesley.  Umbral  of 
Kogers. 

1.  Pocono  group  of 
Lesley.  Vespertine  of 
^  Kogers. 


2.  Coal- measures. 


1.  Millstone  Grit. 


4.  Chester,  or  Kaskas- 
kia  group. 

3.  St.  Louis  group. 
c  Warsaw. 

2'  °SaSe  }  Keokuk. 
grOUp'  (Burlington. 

1.  Kinderhook  group. 


The  Subcarboniferous  rocks  of  the  Mississippi  basin  are  mainly  great 
limestone  formations.  The  term  Subcarboniferous  was  first  applied  to  them 
by  D.  D.  Owen  in  his  Quarto  Keport,  of  1852,  on  the  Geology  of  Wisconsin, 
Iowa,  and  Minnesota.  In  this  report  (page  90)  he  divides  the  Carboniferous 
rocks  of  Iowa  into  "(1)  the  great  calcareous  formation  at  the  base,  (2)  the 
coal-bearing  strata  in  the  middle,  and  (3)  heavy  beds  of  sandstone  at  the  top," 
and  gives  (on  page  92)  a  section  of  the  "  Subcarboniferous  limestones."  On 
the  following  page  he  presents  a  "  table  exhibiting  the  analogy  between  the 
Carboniferous  limestones  of  Yorkshire,  England,  and  those  of  Iowa,"  thus 
applying  the  term,  in  effect,  to  the  corresponding  rocks  of  Great  Britain  and 
Europe.  The  preposition  sub  is  here  used  in  the  same  sense  as  in  substructure; 
and  the  great  limestone  formations  of  the  Mississippi  basin  make  a  grand 
substructure  for  the  coal-measures  or  the  beds  of  the  Carboniferous  period. 
The  term  Mountain  limestone,  used  for  the  British  rocks,  and  for  awhile 
employed  in  the  United  States,  is  not  applicable  to  limestones  of  the  plains. 


PALEOZOIC   TIME  —  CARBONIC.  635 

GENERAL  DISTRIBUTION  OF  THE  ROCKS  OF  THE  ERA. 

The  geological  map  on  page  412,  though  small,  is  sufficiently  detailed  to 
give  a  general  idea  of  the  distribution  of  the  Carboniferous  and  Subcar- 
boniferous  areas  of  the  eastern  part  of  the  continent.  The  former  are 
distinguished  by  doubly  cross-barred  marking ;  the  latter,  which  border 
these,  by  singly  cross-barred,  with  a  cross  in  the  small  squares.  The  several 
areas  of  the  two  combined  formations  are  as  follows :  — 

I.  The  Acadian :  covering  part  of  western  Newfoundland,  of  Nova  Scotia, 
and  of  New  Brunswick. 

II.  The  Rhode  Island:  covering  part  of  Rhode  Island,  and  extending 
northward  and  eastward  into  Massachusetts. 

III.  The  Worcester  area :  about  Worcester,  Massachusetts. 

IV.  The  Michigan  area :  occupying  the  larger  part  of  Michigan  between 
the  southern  half  of  Lake  Huron  and  Lake  Michigan,  having  the  coal- 
measures  over  its  central  portion. 

V.  The  Pennsylvania- Arkansas  area  :  stretching  in  a  zigzag  way  over  25 
degrees  of  longitude  and  12  of  latitude ;  first,  from  the  southern  border  of 
western  New  York,  and  a  line  just  south  of  Lake  Erie,  to  Alabama  and 
Mississippi;   then,  northward  and  westward  to  Illinois  and  Iowa;   thence 
southward  and  westward  again  to  Arkansas  and  Texas.      At  the  western 
limit  commences  the  "Western  Interior  Sea,"  where  the  Carboniferous  strata 
pass  out  of  sight  beneath  those  of  the  Cretaceous.     The  coal-measures  of  this 
area  are  mostly  in  three  parts,  underlaid  and  connected  by  the  Subcar- 
boniferous.     These  parts  are  thus  separate,  either  because  never  united,  or 
more  probably  because  of  the  removal  of  the  coal-measures  that  once  covered 
the  intermediate  Subcarboniferous  beds. 

VI.  Over  the  Western  Interior  and  along  the  summit  region  of  the  Rocky 
Mountains,  but  without  coal,  and  mostly  as  a  limestone  wherever  there  are 
outcrops. 

VII.  Along  parts  of  the  Great  Basin,  being  a  constituent  of  many  of  the 
mountain  ridges;  also  in  the  Sierra  Nevada,  and  in  other  portions  of  the 
Western  border  region. 

VIII.  In  the  Arctic  regions,  along  a  wide  belt  between  the  parallels  of 
72°  and  821°,  northeast  in  course,  from  Banks  Land  on  the  west  to  Grinnell 
Land  on  the  east,  and  reaching  beyond  the  latter  to  83°,  nearly  the  most  north- 
ern point  of  Arctic  exploration.     Also  on  Spitzbergen  and  Bear  Island. 

The  Coal-measures,  or  the  areas  of  the  Carboniferous  period,  have  a  smaller 
range,  and  the  productive  Coal-measures,  a  still  smaller.  Of  the  above  eight 
regions,  only  numbers  L,  II.,  IV.,  and  V.,  to  the  east  of  the  meridian 
of  100°  W.,  are  coal-producing ;  but  the  Arctic  beds  of  Grinnell  Land  afford 
coal,  which  may  be  available  whenever  the  seas  shall  become  navigable. 

The  term  Permo-Carboniferous  is  sometimes  used  for  the  beds  of  the  Car- 
boniferous and  Permian  periods  of  central  and  eastern  North  America, 
because  they  make  an  essentially  undivided  series. 


636  HISTORICAL   GEOLOGY. 

1.    SUBCARBONIFEROUS   PERIOD. 
ROCKS— KINDS   AND  DISTRIBUTION. 

The  Subcarboniferous  period,  like  several  other  periods  of  the  Paleozoic, 
is  noted  for  extensive  limestone  formations  with  thin  shales  and  sandstone 
over  the  Central  Continental  Interior,  or  the  area  of  the  Mississippi  basin ; 
for  sandstones  and  shales,  with  little  limestone,  along  the  Eastern  Interior 
region,  especially  its  northern  bay-like  portion ;  and,  like  all  the  preceding 
periods  after  the  close  of  the  Lower  Silurian,  for  no  deposits  yet  known  over 
the  Atlantic  continental  border  south  of  the  latitude  of  New  York.  The 
peculiarities  of  the  Eastern  Interior  are  attended  by  another  distinctive 
feature:  The  limestones  of  the  Mississippi  basin  abound  in  fossils,  especially 
Crinoids,  Brachiopods,  and  Corals  ;  and,  owing  to  the  Crinoids,  they  are  often 
called  Crinoidal  limestones ;  while  the  fragmental  rocks  to  the  eastward  con- 
tain fewer  fossils,  and  almost  all  of  these  are  of  different  species  from  the 
western,  except  where  limestone  occurs  in  the  series.  Owing  to  the  wide 
differences  in  the  rocks  and  fossils,  there  is  much  difficulty  in  bringing  the 
beds  of  the  two  distant  regions  into  parallelism. 

The  rocks  of  the  lower  of  the  two  groups  in  Pennsylvania,  the  Pocono, 
are  mainly  beds  of  hard  gray  sandstone  and  conglomerate;  and  those  of  the 
upper,  the  Mauch  Chunk,  reddish  shales  and  shaly  sandstones.  In  south- 
western Pennsylvania  a  thin  bed  of  siliceous  limestone  makes  the  top  of  the 
Pocono,  and  a  similar  layer  occurs  also  in  the  upper  shales. 

The  enduring  Pocono  sandstone  is  800  feet  thick  near  Pottsville,  Pa.  It 
extends  northeastward,  capping  at  many  points  the  high  northern  plateau  of 
the  state ;  and  it  also  stretches  southwestward,  making  the  summit,  in 
Bedford  County,  of  the  Alleghanies,  where  it  is  1400  feet  thick  —  holding  its 
place  against  denuding  agencies.  It  is  supposed,  by  Lesley,  to  constitute 
some  hundreds  of  feet  of  the  higher  peaks  of  the  Catskills.  The  overlying 
Mauch  Chunk  shale  is  a  fragile  rock  and  was  easily  swept  off  by  denuding 
waters  from  the  Pocono  floor.  Its  thickness  is  stated  to  be  3000  feet  at 
Pottsville.  The  two  formations  thin  down  to  600  feet,  in  southwestern,  and 
300  feet  in  northwestern,  Pennsylvania. 

The  thickness  of  the  limestone  layers  of  the  Eastern  Interior  increases 
in  West  Virginia;  and  in  the  southwest  counties  of  Virginia  becomes  rather 
abruptly  over  2000  feet  thick.  Farther  south,  in  Tennessee  and  Alabama, 
siliceous  beds  and  cherty  limestones  make  the  chief  parts  of  the  formation, 
and  they  once  covered  the  Silurian  limestone  basin  of  central  Tennessee. 
Some  thin  beds  of  coal  occur  in  the  upper  formation,  and  one  in  southwest 
Virginia,  near  New  Biver,  is  worked. 

In  Ohio,  about  600  feet  of  shale  and  sandstone  are  overlaid  in  some  parts 
by  15  to  20  feet  of  limestone.  In  Michigan,  the  beds  are  chiefly  shales  and 
limestones,  with  less  than  70  feet  of  limestone  in  the  upper  part. 

The  limestones  of  the  Mississippi  basin,  with  the  included  shales  and  sand- 


PALEOZOIC   TIME  —  CARBONIC.  637 

stone,  —  constituting  the  Mississippian  group  of  Williams,  —  have  an  aggre- 
gate thickness  in  southwestern  Illinois  of  1200  to  1500  feet.  They  thin  out 
northward  in  this  state  before  reaching  Eock  Island  County  ;  and  beyond,  the 
coal-measures  rest  on  the  Devonian.  These  limestones  extend  in  part  into 
Iowa,  Indiana,  Kentucky,  Missouri,  and  southward  into  Texas.  The  Kinder- 
hook  group  extends  far  into  Iowa;  but  after  its  deposition  a  long  retreat  of 
the  shore  line  took  place  before  the  Burlington  beds,  the  first  part  of  the  Osage 
group,  were  deposited ;  and  this  retreat  was  continued  after  the  deposit  of 
the  Burlington  group.  But  before  the  St.  Louis  epoch  began  there  was  a  sub- 
sidence, allowing  of  an  advance  again  northward,  as  the  northward  extension 
of  the  beds  shows.  There  is  thus  unconforinability  by  overlap  of  the  St. 
Louis  limestone  over  the  underlying  beds,  as  stated  by  C.  A.  White  (1870, 
Eep.  Iowa). 

The  subdivisions  of  the  Mississippian  group  in  Illinois  and  the  adjoining  parts  of  the 
Central  Interior  area  are  arranged  as  follows  by  C.  K.  Keyes  (G.  S.  A.,  1892):  — 

1.  The  Kinderhook  Group.  —  This  group  was  so  named  by  Meek  and  Worthen  (1861). 
The  "Lithographic  limestone,"  "Vermicular  sandstone  and  shales,"  and  "  Chouteau  lime- 
stone "  of  Missouri,  are  three  rather  persistent  divisions.     The  term  Louisiana,  from  a  place 
in  Pike  County,  Mo.,  is  used  by  Keyes  in  place  of  Lithographic,  and  Hannibal  shales  for 
Vermicular  sandstone  and  shales.     The  "Louisiana"  limestone  is  60'  thick  in  Missouri. 
The  Hannibal  shales  are  reported  from  Iowa,  as  well  as  Missouri,  with  a  thickness  of  70'  to 
150'  or  more.     The  Chouteau  is  a  fine  buff-colored  limestone,  10'  to  15'  thick  at  Hannibal 
and  Louisiana,  100'  or  more  at  Sedalia,  in  Missouri,  and  perhaps  50'  at  Burlington,  Iowa. 
The  Goniatite  limestone  of  Rockford,  Ind.,  was  referred  to  the  horizon  of  the  Chouteau 
by  Meek.     The  larger  part  of  the  "  Knobstone  group  "  of  sandstones  and  shales  (partly 
calcareous),  which  makes  the  eastern  border  of  the  Carboniferous  area  of  Indiana,  is 
referred  to  the  Kinderhook. 

2.  The  Osage  Group.  —  The  subdivisions  of  the  Osage  group  —  so  named  by  H.  S. 
Williams  —  are:  (1)  Lower  Burlington,   (2)  Upper  Burlington,   (3)  Keokuk,  with  the 
"geode-bed"  and  the  Warsaw  shales  and  limestone.     The  Lower  Burlington  is  described 
as  having  Crinoids  of  delicate  forms ;  the  Upper,  of  stouter  forms ;  the  Keokuk,  of  still 
coarser  and  larger  kinds,  massive  in  construction.     The  geode-bed  is  a  bed  of  blue  shale, 
30'  to  35'  thick,  containing  thin  layers  of  limestone.     The  geodes  are  sometimes  2'  in 
diameter ;  they  contain  within :  quartz  crystals,  agate,  crystals  of  calcite,  dolomite,  and 
often  pyrite,  sphalerite,  millerite  (in  hair-like  needles,  or  tufts  of  needles),  besides  other 
minerals.     An  extermination  of  a  large  part  of  the  Keokuk  species  occurred  at  the  close  of 
the  epoch. 

3.  The  St.  Louis  Group.  — The  St.  Louis  limestones  were  so  named  by  Shumard  from 
the  evenly  bedded  limestone  of  St.  Louis,  Mo.    They  are  oolitic  3  miles  above  Alton. 
The  northern  limit  in  north-central  Iowa,  near  Fort  Dodge,  is  the  evidence  of  the  north- 
ward return  of  the  shore  line  for  several  hundred  miles  beyond  the  limit  of  the  Keokuk, 
and  here  the  beds  are  fossiliferous  marls.     In  St.  Genevieve  County,  Mo.,  the  thickness  of 
the  beds  is  over  300',  and  it  is  still  greater  to  the  southeastward.     The  rock  at  Spergen 
Hill,  Ind.,  is  of  this  division. 

4.  The  Chester  or  Kaskaskia  Group.  —  This  group  includes  limestone,  in  three  or 
four  beds,  with  intercalated  shale  and  sandstone,  aud  sandstone  below  ;  it  is  occasionally 
800' thick.    It  comprises  the  "  Pentremital "  limestone,  and  the  "Upper  Archimedes" 
limestones,  called  also  the  "Kaskaskia"  limestone.     The  stratum  of  sandstone  at  the 


638  HISTORICAL   GEOLOGY. 

bottom  is  the  ferruginous  sandstone  of  Shumard.  The  sandstone  is  regarded  by  C.  R. 
Keyes  as  having  been  made  while  a  final  retreat  of  the  shore  line  was  in  progress.  He 
names  it  the  "  Aux  Vases"  sandstone. 

The  section  of  the  Subcarboniferous  at  Burlington,  Iowa,  includes :  (1)  of  the  Kinder- 
hook,  50'+  of  clay  shale  ;  (2)  20'- 30',  soft  shaly  sandstone  ;  (3)  gray  impure  limestone, 
often  oolitic  below,  9'- 13';  (4)  fine  sandstone,  6';  (5)  gray  oolyte,  4';  (6)  buff  limestone,  5', 
of  the  Lower  Burlington  ;  (7)  brown  and  gray  encrinal  limestone,  27';  (8)  buff  calcareous 
and  siliceous  shales,  with  thin  limestone  layers  and  chert,  23',  of  the  Upper  Burlington ; 
(9)  gray  encrinal  limestone,  somewhat  cherty,  30';  (10)  impure  limestone  with  chert 
nodules  and  seams,  20'  (Keyes).  The  Keokuk  exposures  include  about  100'  of  Keokuk 
below  and  above  Warsaw  and  St.  Louis  beds. 

Keyes  has  further  reported  (Dec.,  1892)  the  discovery,  in  northeastern  Missouri,  of  a 
bed  of  the  Kinderhook  limestone,  containing  its  typical  fossils,  and  these  chiefly  Mollusks, 
intercalated  in  the  overlying  Burlington  group,  where  typical  in  its  fauna,  and  this  chiefly 
crinoidal,  and  without  a  change  in  lithological  characters  or  the  purity  of  the  limestone 
beds.  It  shows,  as  Keyes  observes,  that  the  Kinderhook  and  Burlington  stages  were  not 
wholly  successive  as  regards  time ;  that  after  the  Burlington  group  had  made  progress,  the 
Kinderhook  species  still  existed,  for  a  while  at  least,  outside  of  their  former  limits,  but 
ready  to  return  when  the  conditions  favored.  In  Missouri,  the  whole  thickness  of  the  Sub- 
carboniferous  limestone  is  1150'. 

In  Indiana,  the  "  Knobstone,"  below  the  Keokuk,  has  a  thickness  in  some  places  of 
500',  the  Keokuk  of  100',  the  St.  Louis  of  330',  and  the  Chester  of  75';  the  latter  consists 
of  sandstones  alternating  with  limestones.  In  Lawrence  County,  an  irregular  bed,  or 
series  of  pockets,  of  porcelain  clay,  ranging  to  6'  in  thickness,  lies  at  the  top  of  the  Chester 
limestone,  over  a  bed  of  iron  ore.  About  a  third  is  of  pure  white  color.  It  has  been 
called  indianaite;  with  it  occurs  the  mineral  allophane. 

In  Michigan,  the  Subcarboniferous  consists  of  four  groups  of  strata,  according  to 
A.  Winchell:  (1)  or  lowest,  173'  of  grit  and  sandstone,  called  the  Marshall  Group;  (2) 
123'  of  shale  and  sandstone,  the  Napoleon  Group ;  (3)  184'  of  shale  and  marlyte,  with 
some  limestone  and  gypsum,  the  Michigan  Salt-group  ;  (4)  the  Carboniferous  limestone, 
66'  thick.  This  limestone  is  well  exposed  at  Grand  Rapids.  The  Marshall  group  is  made 
the  equivalent,  in  part,  of  the  Kinderhook;  and  the  limestone,  at  the  top,  the  equivalent 
of  the  Chester  and  St.  Louis  groups. 

In  Ohio,  the  Subcarboniferous  beds  comprise  the  Waverly  group. 

In  northwestern  Pennsylvania,  the  Subcarboniferous  is  in  the  main  equivalent  to  the 
Waverly.  I.  C.  White  has  recognized  three  divisions :  (1)  the  Oil-creek  group,  the  equiva- 
lent, it  is  believed,  of  the  Pocono  ;  (2)  Meadville  group  ;  and  (3)  Shenango  group.  In 
Warren  County,  the  Panama  conglomerate  is  more  than  200'  below  the  top  of  the  Che- 
mung,  and  may  be  recognized  by  abundant  remains  of  Ptychopteria.  The  Waverly  con- 
sists of  shaly  sandstones  in  its  lower  third,  followed  by  a  conglomerate  (=  Sub-Olean  ?) 
above  which  are  thin-bedded  buff  sandstones. 

In  West  Virginia,  the  Lower  Subcarboniferous  occurs  along  the  middle  portion  of  the 
main  Alleghany  Mountains,  from  the  Potomac  southward.  In  Greenbrier  County,  near 
the  White  Sulphur  Springs,  it  includes  a  stratum  of  limestone  822'  thick,  with  1260'  of 
shales  and  sandstone.  The  limestone  to  the  north,  in  Monongalia  County,  was  found  by 
Meek,  through  its  fossils,  to  be  the  probable  equivalent  of  the  Chester  group. 

In  middle  Tennessee,  according  to  Safford,  the  Siliceous  group  consists,  commencing 
below,  of  (1)  the  Protean  beds,  cherty  and  argillaceous,  with  some  limestone,  250'  to  300', 
and  (2)  the  Lithostrotion  or  Coral  beds,  an  impure  cherty  limestone,  the  equivalent  of  the 
St.  Louis  limestone,  about  250'  thick.  The  Upper  member  is  limestone,  400'  thick  on 
the  northern  borders  of  the  state,  an&  720'  on  the  southern.  These  two  divisions  occur 
also  in  eastern  Kentucky.  The  Upper  member  also  extends  into  the  northeast  corner  of 
Mississippi,  where  it  is  overlaid  by  Cretaceous  beds  (Hilgard).  At  Huntsville,  Ala., 


PALEOZOIC   TIME  —  CARBONIC. 


639 


Worthen  found  it  to  consist  principally  of  gray  limestone,  partly,  oolitic,  partly  cherty,  with 
some  shaly  beds,  in  all  about  900'.  The  larger  portion  of  the  series  yields  Chester  fossils  ; 
but  characteristic  forms  of  the  St.  Louis  group  mark  the  age  of  the  lowest  250'  to  300'. 

In  Nova  Scotia  and  New  Brunswick,  the  Subcarboniferous  rocks  are :  (1)  the  Horton 
series,  consisting  of  red  sandstones,  conglomerates,  red  and  green  marlytes ;  and,  above 
these,  (2)  the  Windsor  series,  consisting  of  thick  beds  of  limestone,  full  of  fossils,  with 
some  red  marlytes,  and  beds  of  gypsum,  affording  the  gypsum  exported  from  Nova  Scotia 
and  New  Brunswick.  Thus  the  upper  part  is  calcareous,  as  in  Ohio,  Tennessee,  and  West 
Virginia.  The  estimated  thickness  is  6000'.  To  the  north,  toward  the  Archsean,  the 
limestones  fail ;  and,  instead,  the  rocks  are  to  a  greater  extent  a  coarse  conglomerate.  To 
the  south,  limestones  prevail.  The  best  exposures  of  the  lower  or  Horton  series  are  at 
Horton  Bluff,  Hillsborough,  and  other  places  in  southern  New  Brunswick. 

In  the  lower  part  of  these  Subcarboniferous  beds,  as  in  those  of  Virginia,  there  are,  on 
a  small  scale,  "false"  Coal-measures,  and,  in  one  instance,  a  bed  of  erect  trees,  under- 
clays,  and  thin  coal  seams  ;  and  the  same  beds  contain  numerous  remains  of  fishes.  The 
fish-bearing  shales  of  Albert  Mine,  New  Brunswick,  are  of  this  period  (Dawson) . 

Rocky-Mountain  and  Pacific-border  regions. — Over  large  portions  of  these  regions, 
the  limestones  of  the  Subcarboniferous  have  not  been  distinguished  from  those  of  the 
following  period.  In  most  cases  their  recognition  only  waits  for  the  more  careful  study  of 
the  fossils ;  but,  at  many  points,  these  appear  to  be  wanting.  They  have  been  identified 
in  the  Elk  Mountains,  and  other  ranges  of  the  crest  chain  of  the  mountains  in  western 
Colorado  ;  on  the  eastern  slopes  of  the  Wind  River  Mountains,  in  Wyoming.  In  Montana, 
at  "Old  Baldy,"  near  Virginia  City,  tiiere  are  fossils  of  the  Chester  group,  and  probably 
the  Lower  Subcarboniferous  beds  are  also  present  (Meek).  In  Idaho,  near  Fort  Hall, 
Bradley  found  masses  of  limestone  filled  with  minute  shells,  many  species  of  which  Meek 
has  identified  with  forms  characteristic  of  the  oolitic  beds  of  the  St.  Louis  group,  at  Spergen 
Hill,  Ind. 

LIFE. 

PLANTS.  —  The  vegetation  of  the  period  included  species  of  Lycopods 
of  the  genera  Lepidodendron,  Sigillaria,  Knorria  ;  Ferns  of  the  Devonian 
genera,  Archceopteris,  Neuropteris, 
fiphenopteris,  Odontopteris,  with  spe- 
cies also  of  the  new  genera  Alethop- 
teris,  Lesley  a  ;  Equiseta  of  the  genera 
Calamites,  Sphenophyllum,  and  Aste- 
rophyllites;  and  Cycads,  under  Gym- 
nosperms,  of  the  genus  Cordaites ; 
and  among  the  fossil  fruits,  those 
of  Cordaites,  and  probably  some  of 
Conifers  of  the  Yew  family. 

ANIMALS.  1.  Spongiozoans.  — 
Several  sponges  have  been  described 
of  the  genera  Palceacis  (which  has 
deep  cup-like  cavities),  Physospon- 
gia,  etc.  Hexactinellid  sponges  are 
common  in  the  beds  at  Crawfords- 

ville,  Ind.  The  chert,  which  occurs  in  many  beds,  abounds  in  sponge  spi- 
cules. 


991. 


991  a. 


POLYP-CORAL. —  Fig.  991,  portion  of  the  Coral,  Litho- 
strotion  Canadense ;  991  a,  vertical  view  of  the  same. 
Meek  and  Worthen. 


640 


HISTORICAL  GEOLOGY. 


2.  Actinozoans,  Echinoderms.  —  The  animal  life  was  remarkable  for  the 
abundance  of  a  species  of  Lithostrotion,  represented  in  Fig.  991,  and  for  a 
great  profusion  and  diversity  of  Crinoids.  This  Lithostrotion  is  often  colum- 
nar in  the  external  form  of  parts  of  masses  (as  shown  in  Fig.  991  a),  although 
essentially  a  massive  coral.  Among  other  Corals  the  old  genera  Zaphrentis 
and  Cyatliopliyllum  have  their  species,  but  not  Favosites,  Michelinia,  Gysti- 
phyllum,  Dipliypliyllum,  Sarcinula,  and  others  that  were  common  in  the  De- 
vonian. Species  of  Lithostrotion  have  been  found  in  the  Arctic  lands 
between  Point  Barrow  and  Kotzebue  Sound. 

992-1003. 


ECHINODERMS.  —  Fig.  992,  Scaphiocrinus  Missourieasis ;  993,  Actinocrinus  proboscidialis ;  994,  Dorycrinus 
unicornis ;  995,  Woodocrinus  elegans  ;  99X6,  Batocrinus  Christyi ;  997,  Platycrinus  Saffordi ;  998,  the  proboscis 
of  Batocrinus  longirostris  ;  999,  Pentremites  pyriformis  ;  1000,  1000  a,  P.  Godoni ;  1000  a,  top  view ;  1001, 
portion  of  the  shell  of  Archseocidaris  Wortheni ;  1002,  spine  of  A.  Shumardiana  (x  2);  1002  a,  base  of  spine  ; 
1003,  id.  of  A.  Norwoodi.  Figs.  992-995,  99T-1003,  Hall ;  996,  Swallow. 

The  number  of  species  of  Crinoids  described  from  the  American  Sub- 
carboniferous  limestone  exceeds  650.  Some  of  the  forms  are  represented  in 
Figs.  992  to  1000,  but  mostly  wanting  the  arms  and  stem,  as  is  common  with 
these  fragile  species.  Fig.  995  represents  the  perfect  body  of  Woodocrinus 
elegans,  with  the  arms  closed  together,  and,  below,  a  few  segments  of  the 
pedicel,  which,  entire,  may  have  been  a  foot  long;  992  is  a  Scaphiocrinus, 
with  the  arms  broken.  In  Poteriocrinus  Coxanus  Worthen,  t{ie  arms  are  six 
inches  long,  and  the  breadth  of  the  expanded  Crinoid  must  have  been  nearly 


PALEOZOIC   TIME  —  CARBONIC.  641 

a  foot.  Figs.  993,  994,  996,  997  are  the  bodies  of  different  species  of  Crinoids 
without  the  radiating  arms.  The  Crinoids  often  have  a  long  or  short  pro- 
boscis-like projection,  at  the  center  above,  which  is  made  of  stout  calcareous 
pieces  like  the  body,  out  is  tubular;  it  is  seen  broken  off  in  Figs.  993  and 
996;  and  Fig.  998  represents  one  separate  from  the  body  of  a  Batocrinus 
(near  that  of  Fig.  996),  showing  the  calcareous  pieces  constituting  it.  Fine 
figures  of  the  Subcarboniferous  Crinoids,  illustrating  the  wonderful  diversity 
of  forms  among  them,  are  contained  in  the  Illinois,  Iowa,  and  Ohio  geologi- 
cal reports.  In  some  species  the  length  and  form  of  the  proboscis  (which 
contains  the  anal  or  excretory  tube,  not  that  to  the  mouth)  are  very  re- 
markable. 

Two  species  of  Pentremites,  armless  bud-shaped,  five-sided  species,  of  the 
tribe  of  Blastoids,  eminently  characteristic  of  the  Subcarboniferous,  are  rep- 
resented in  Figs.  999,  1000. 

1004.  1005. 


ECHINOIDS.  —Fig.  1004,  Oligoporus  nobills  (x  £) ;  1005,  Melonites  multiporus,  view  of  top  (x  2).    Meek  and 

Worthen. 

Echinoids  were  of  large  size,  and  were  unlike  modern  species  in  the 
excessive  number  of  vertical  series  of  plates  between  the  ambulacral  areas. 
One  species  (Fig.  1004)  has  5  series  of  these  plates,  instead  of  the  normal  or 
modern  number,  two.  In  Archceocidaris  (a  portion  of  a  shell  of  one  species 
of  which  is  shown  in  Fig.  1001),  the  spines  with  which  the  shell  was  bristled 
were  (as  in  modern  species  of  Cidaris)  of  large  size  and  few  (like  Fig.  1002 
in  form),  as  the  large  prominences  over  the  shell  (Fig.  1002 a)  indicate;  but 
in  Fig.  1004  they  were  very  small.  Fig.  1005  is  a  top  view,  enlarged,  of 
Melonites  multiporus.  One  very  large  slab  in  the  Yale  Museum,  from  St. 
Louis,  Mo.,  contains  11  Melonites  to  a  square  foot.  The  generic  name  alludes 
to  the  resemblance  in  form  to  a  melon. 

3.  Molluscoids.  —  Of  Molluscoids,  the  screw-shaped  Bryozoans,  species  of 
Archimedes,  Fig.  1006,  are  characteristic.     The  screw  has  lost  the  larger 
DANA'S  MANUAL  —  41 


642 


HISTORICAL    GEOLOGY. 


1006. 


1007. 


part  of  the  .blade,  the   part  that  carries,  on  its  under  surface,  the  cells 
occupied  by  the  animals,  as  illustrated  in  Figs.  1007  a  and  1007  b. 

Brachiopods  were  numerous,  especially  of  the 
genera  Productus  (Fig.  1013),  Chonetes  (Figs.  1012, 
1015),  Spirifer  (1010,  1014),  Athyris,  Dielasma 
and  Rhynchonella.  There  were  also  species  of  the 
Lower  Silurian  genus  Orthis  (Fig.  1008),  but  none 
of  Stropheodonta,  Merista,  Meristella,  so  well  rep- 
resented in  the  Devonian. 


4.  Mollusks.  —  Among  Mollusks,  Lamelli- 
branchs  were  common.  Under  Gastropods,  the 
genus  Bellerophon,  which  first  appears  in  the  Cam- 
brian ;  the  Lower  Silurian  genera,  Euomphalus, 
Murchisonia,  Pleurotomaria,  and  the  Upper  Si- 
lurian Platyceras,  Loxonema,  and  Macrocheilus, 
which  had  many  Devonian  species,  were  still  well 
represented.  The  shells  of  Platyceras  are  often 
attached  to  a  Crinoid,  like  those  of  a  modern  Crepidula  to  an  oyster. 

Cephalopods  were  of  many  kinds  under  the  old  genus  Orthoceras;  and 
Discites,  Goniatites,  Gyroceras,  had  their  species.  Nautilus  (Endolobus  of 
Hyatt)  spectabilis  M.  and  W.,  from  the  Chester  limestone,  was  two  feet  in 


BRYOZOANS.  —  Figs.  1006,  1007  a,  6, 
Archimedes  Wortheni  (1007  a  and 
10076,  xf).  Hall. 


1008 


1008-1015. 
1011 


1014 


BEACHIOPODS.  — 1008,  Orthis  Michelini  var.  Burlingtonensis  ;  1009,  Spiriferina  spinosa  ;  1010,  Spirifer  increbes- 
cens  ;  1011,  Eumetria  Verneuiliana ;  1012,  Chonetes  Illinoisensis ;  1013,  Productus  punctatus ;  1014,  Spirifer 
biplicatus  ;  1015,  1015  a,  Chonetea  ornatus.  Figs.  1008-1011,  Hall ;  1012,  Koninck  ;  1013,  Meek ;  1014,  1015, 
Swallow. 

diameter;  Orthoceras  nobile  M.  and  W.,  of  Illinois,  was  five  to  six  feet  long, 
and  a  foot  in  diameter;  and  Gyroceras  Burlingtonense  Owen,  five  inches  in 
diameter.  The  species  represented  in  Figs.  1016, 1017  are  from  the  Goniatite 
bed  of  Rockford,  Ind. 


PALEOZOIC   TIME  —  CAKBONIC. 


643 


5.  Crustaceans.  —  TriloUtes  were  of  twenty  or  more  species,  all  small  prini- 
looking  forms,  of  the  Devonian  genera  Proetus,  Phcethonides,  and  the  related, 
but  low-featured,  Carboniferous  genera  Griffith! des  and  Phillipsia.  Half  of 
the  twenty  species  are  of  the  genus  Phillipsia. 

The  other  Crustaceans  known  from  the  beds  are  Phyllopods  and  Ostracoids; 
and  the  shells  of  a  Beyrichia  make  the  chief  part  of  the  material  of  a  layer 
four  feet  thick,  north  of  Pella,  Iowa. 


1016. 


1016  a. 


1017. 


CEPHALOPODS.  —  Fig.  1016,  Goniatites  Oweni;  1016 a,  id.,  outline,  showing  direction  of  septa;  1017,  G.  (Pro- 
lecanites)  Lyoni ;  1017  a,  id.,  direction  of  septa.     Hall. 

6.  Insects.  —  Remains  of  Insects,  and  other  terrestrial  species,  are  neces- 
sarily rare  in  marine  deposits,  and  no  species  have  yet  been  reported. 

7.  Vertebrates.  —  Vertebrates  were  represented  by  Ganoids  and  Selachians, 
as  in  the  Devonian,  but  with  apparently  no  Placoderms.     There  were  also 
the  first  yet  known  of  Amphibians. 

The  remains  of  Selachians  are  teeth  and  fin-spines.  The  teeth  are  either 
of  the  pavement  kind,  allied  to  those  of  the  living  Cestracion  (or  Port  Jack- 
son Shark),  and  to  Myliobatis  (or  Eagle  Ray),  or  of  pointed  and  triangular 
form,  more  or  less  resembling  some  of  the  modern  type  referred  to  the 
Hybodont  and  Petalodont  families. 

Of  the  pavement-mouthed  forms,  the  Cochliodonts,  which  have  a  large 
massive  plate  on  either  ramus  of  the  jaw,  were  numerous  in  the  Subcarbo- 
niferous.  One  of  these  plates  is  represented,  natural  size,  in  Fig.  1018,  from 
Worthen's  Illinois  Report;  and  the  form  for  the  whole  jaw  in  a  foreign 
species  is  shown  one  third  the  natural  size  in  Fig.  1019.  Over  50  species  are 
described  from  the  Illinois  limestone.  The  Psammodonts,  having  the  inner 
surface  of  the  jaw  covered  by  flat  rectangular  plates,  nearly  as  in  Myliobatis, 
have  over  a  dozen  Subcarboniferous  species  of  the  genera  Psammodus  and 
Copodus.  A  Petalodont  tooth,  Petalodus  curtus,  has  been  reported  from  the 


644 


HISTORICAL   GEOLOGY. 


Keokuk  limestone.  The  Cestracionts  (see  page  416),  with  a  rough,  uneven 
pavement,  were  represented  by  species  of  Helodus  and  Orodus.  Some  of  the 
sharp-pointed  teeth  of  Hybodonts  are  shown  in  Figs.  1020-1022  (Newberry 
and  Worthen) . 


1018. 


1019. 


TEETH  OF  CESTRACIONT  SHARKS.  —Fig.  1018,  Cochliodus  nobilis  ;  1019,  C.  contortus  (x  £).     Fig.  1018,  Meek  ; 

1019,  Agassiz. 

Fin-spines  of  Sharks  are  various  in  size  and  form.  One,  of  Ctenacanthus, 
has  a  length  of  a  foot;  and  others,  now  broken,  were  probably  6  inches  longer ; 
they  indicate  fins  of  large  size,  and  therefore  the  existence  of  great  Sharks. 


1020. 


1021. 


TEETH  OF  SHARKS.  —  Fig.  1020,  Carcharopsis  Wortheni ;  1021,  Cladodus  spinosus ;  1022,  Orodus  mammillaris. 

Newberry. 

Amphibians  are  known  from  their  footprints  on  a  layer  of  the  Mauch 
Chunk  shale  near  Pottsville,  in  Pennsylvania,  as  described  by  Isaac  Lea. 
A  reduced  view  of  the  slab  is  shown  in  Fig.  1023.  There  is  a  succession  of 
six  steps,  along  a  surface  little  over  five  feet  long;  each  step  is  a  double  one, 
as  the  hind-feet  trod  nearly  in  the  impressions  of  the  fore-feet.  The  prints 
were  hand-like;  that  of  the  fore-foot  five-fingered  and  four  inches  broad;  that 
of  the  hind-foot  somewhat  smaller,  and  four-fingered.  That  the  Amphibian 
was  therefore  large,  is  also  evident  from  the  length  of  the  stride,  which  was 
thirteen  inches,  and  the  breadth  between  the  outer  edges  of  the  footprints. 


PALEOZOIC    TIME  —  CARBONIC.  645 

eight  inches.  There  is  also  a  distinct  impression  of  a  tail,  an  inch  or  more 
wide.  The  slab  is  crossed  by  a  few  distinct  ripple-marks  (eight  or  nine 
inches  apart),  which  are  partially  obliterated  by  the  tread.  The  whole  sur- 
face, including  the  footprints,  is  covered  throughout  with  rain-drop 
impressions. 


Tracks  of  Sauropus  primaevus  (x  J).      I.  Lea. 

We  thus  learn  that  in  the  region  about  Pottsville  a  mud-flat  was  left  by 
the  retreating  waters,  perhaps  those  of  an  ebbing  tide,  covered  with  ripple- 
marks;  that  the  ripples  were  still  fresh  when  a  large  Amphibian  crossed 
the  flat ;  that  a  brief  shower  of  rain  followed,  dotting  with  its  drops  the 
half-dried  mud ;  that  the  waters  again  flowed  over  the  flat,  making  new  de- 
posits of  detritus,  and  so  buried  the  records.  The  records  were  opened  and 
deciphered  in  1849  by  Dr.  Lea. 

Char  act  e  ristic  Species . 

PLANTS.  — In  the  Subcarboniferous  of  Pennsylvania  occur,  according  to  Lesquereux, 
Archceopteris  obtusa  Lx.,  and  A.  minor  Lx.  (both  found  in  the  Chemung  of  the  Devonian) , 
A.  Bockschiana  Gopp.;  remains  of  Lepidodendron,  as  L.  corrugatum  Dn.,  and  Stigmaria 
minuta  Lx. ;  in  Illinois,  in  the  Chester  group,  the  Ferns  Megaphyton  protuberans  Lx., 
Caulopteris  Wortheni  Lx.,  Alethopteris  Helena?  Lx.,  Neuropteris  capitata  Lx.,  Pseudope- 
copteris  anceps  Lx.,  Rhacophyllum  flabellatum  St.,  Sphenopteris  cristata  St.,  Megalopteris 
fasciculata  Lx.  ;  also  Lepidodendron  costatum  Lx. ,  L.  turbinatum  Lx.,  L.  obscurum  Lx., 
L.  Veltheimanum  St.,  L.  Wortheni  Lx.,  Stigmaria  anabathra  Corda,  S.  minor  Gopp.,  S. 
umbonata  Lx.,  Knorria  imbricata  St.,  Calamites  Suckovi  Bngt.,  Asterophyllites  equiseti- 
formis  Schl. ,  and  others. 

In  the  Chester  group  of  Indiana,  according  to  Collett,  occur  Stigmaria,  Lepidodendron 
aculeatum  St.,  L.  diplostegioides  Lx.,  L.  forulatum  Lx.,  Lepidostrobus,  Knorria,  Neurop- 
teris biformis,  Alethopteris,  etc.  One  specimen  of  Lepidodendron  had  portions  of  the 
leaves  attached  to  the  stem,  which  were  12  to  14  inches  long,  though  only  from  one  eighth 
to  one  fourth  of  an  inch  in  width. 

In  the  Subcarboniferous  of  Nova  Scotia  and  New  Brunswick,  Dawson  has  made  out 
the  following  species:  FERNS —  Cyclopteris  Acadica  Dn. ,  Cardiopteris,  Hymenophyllites ; 
LYCOPODS  —  Ptilophyton  plumula  Dn.,  the  last  of  the  genus,  Lepidodendron  corrugatum 
Dn.  (near  L.  Veltheimanum  of  Europe),  L.  tetragonum  St.,  L.  obovatum  St.,  L.  dichoto- 


646  HISTORICAL   GEOLOGY. 

mum  St.,  L.  aculeatum  St.,  also  Stigmaria  ficoides  Brngt.,  Cordaites  borassifolius  St., 
Dadoxylon  antiquum  Dn. 

The  metamorphic  Carboniferous  region  of  Worcester,  Mass. ,  where  the  slates  are  mica 
schist,  have  afforded  I.  H.  Perry  specimens  of  Lepidodendron  (Sagenaria)  acuminatum 
G6pp.,  as  identified  by  Lesquereux  {Am.  Jour.  Sc.,  xix.,  1885).  It  is  doubtful  whether 
the  plant  is  Subcarboniferous  or  Carboniferous. 

See,  further,  Pa.  G-eol.  Rep.,  No.  P. ;  III.  Geol.  Hep.,  vols.  ii.  and  iv.  ;  Ind.  Geol.  Rep. 
for  1883  ;  Damson's  Hist.  Plants,  1888,  etc. 

ANIMALS.  —  1.  Rhizopods.  —  Endothyra  Baileyi  H.  occurs  in  the  St.  Louis  limestone 
of  Indiana. 

2.  Spongiozoans.  —  The  hornstones  of  the  limestones  in  Illinois  and  Indiana  abound  in 
microscopic  spicules  of  sponges,  with  a  few  Desmid-like  forms  similar  in  general  to  those 
of  the  Corniferous  limestone  (page  583)  (M.  C.  White).     Palceacis  (Sphenopterium}  obtu- 
sus  M.  &  W.,  Keokuk  limestone,  P.  Cuneiforms  M.  Edw.,  St.  Louis  limestone.     In  the 
Keokuk  occur  many  Hexactinellid  sponges  of  the  genera  -Hydnoceras,  Physospongia, 
Phragmodictya. 

3.  Actinozoans.  —  Fig.  991,  Lithostrotion  Canadense  Castelnau,  St.  Louis  1. ;  L.  pro- 
liferum  H.,  St.  Louis  group;  Zaphrentis  spinulosa  E.  &  H.  ;  Z.  minas  Dn.,  West  Kiver, 
Pictou  ;  Cyathophyllum  Billingsi  Dn.,  Nova  Scotia. 

4.  Echinoderms.  —  (a)  Blastoids :  Fig.  999,  Pentremites  pyriformis  Say,  Kaskaskia  1. ; 
1000,  P.  Godoni  Defr.,  ibid.,  and  50  other  species  of  this  and  the  related  genera  Granato- 
crinus  and  Troostocrinus. 

(6)  Crinoids. — Fig.  992,  Scaphiocrinus  Missouriensis  Shum.,  St.  Louis  1.  ;  993,  Acti- 
nocrinus proboscidialis  H.,  Burlington  1.  ;  994,  Dorycrinus  unicornis  Owen  &  Shum.,  ibid. ; 
995,  Woodocrinus  elegans  H.,  ibid.;  996,  Batocrinus  Christyi  Shum.,  arms  broken  off, 
ibid.  ;  998,  proboscis  of  Batocrinus  longirostris  H.,  ibid. ;  997,  Platycrinus  Saffordi  Troost, 
side-view,  Keokuk  1.  The  most  prolific  locality  of  Crinoids,  as  yet  known,  is  Burlington, 
Iowa,  where  over  350  species,  representing  over  50  genera,  were  collected  by  Mr.  C.  Wachs- 
muth,  besides  6  Echinoids,  4  Asterioids,  and  1  Ophiuroid.  Many  of  them  are  described 
by  Hall  in  his  Iowa  report  of  1858.  The  Keokuk  beds  of  Crawfordsville,  Ind.,  have  yielded 
50  species.  The  genera  most  numerously  represented  are  Actinocrinus,  Cyathocrinus, 
Dichocrinus,  Batocrinus,  Platycrinus,  Poteriocrinus,  Scaphiocrinus,  and  Zeacrinus. 

(o)  Echinoids.  — Fig.  1001,  Archceocidaris  Wortheni  H.,  St.  Louis  1. ;  1002,  A.  Shumar- 
dana  H.,  St.  Louis  1. ;  1003,  plate  of  A.  Norwoodi  H.,  Chester  1.  ;  1005,  Melonites  mul- 
tiporus  0.  &N.,  St.  Louis  1.  ;  1004,  Oligoporus  nobilis  M.  &  W.,  Burlington  1.  Figs.  1004, 
1005  are  from  Worthen's  Report  on  the  Geology  and  Paleontology  of  Illinois. 

(d)  Asterioids  and  Ophiuroids.  —  Worthen  and  S.  A.  Miller  have  described  (in  III. 
Rep.,  vii.,  1883),  from  Illinois,  Compsaster  formosus,  Chester  limestone;  Cholaster  pecu- 
liaris,  ibid.,  and  the  Ophiuroid  Tremataster  disparilis,  ibid. 

5.  Molluscoids.  —  (a)  Bryozoans.  —  Fig.  1006,  Archimedes  Wortheni  H.,  being  a  portion 
of  the  spiral  axis,  with  the  reticulated  expansion  of  the  spiral  worn  off.     Fig.  1007  a,  a  por- 
tion of  the  reticulated  expansion,  magnified  and  showing  the  upper  surface.     Fig.  1007  b, 
the  under  or  cell-bearing  side  of  the  same. 

(6)  Brachiopods.  —  Kinderhook  :  Spirifer  Cooperensis  Swallow  ;  8.  Marionensis, 
Chonetes  ornatus  Shum.  (Fig.  1015),  1015  a,  surface  enlarged,  Lithographic  and  Chouteau 
limestone,  Mo.  ;  1014,  Spirifer  biplicatus  H.  Burlington  1. :  1008,  Orthis  Michelini 
L'Eveille  (var.  Burlingtonensis  H.),  Spirifer  Meeki,  S.  Logani,  Productus  Flemingi  Sow. 
Keokuk  1. :  Actinoconchus  planosulcatus  Phill.,  111.,  Chonetes  planumbonus  M.  &  W.,  Iowa, 
Camarophona  subtrigona  M.  &  W.,  111.,  etc.,  Spirifer  Keokuk  H.  St.  Louis  1. :  Productus 
scitulus  M.  &  W.,  1011,  Eumetria  Verneuilana  H.,  Warsaw,  Spiriferina  spinosa  N.  &  P., 
Warsaw,  Lower  Archimedes,  Mo.  Chester  1. :  1010,  Spirifer  increbescens  H.,  Kaskaskia 


PALEOZOIC   TIME  —  CARBONIC.  647 

limestone,  Spirifer  glaber  var.  contractus  M.  &  W.,  1009,  Spiriferina  spinosa  ;  1012,  Chonetes 
lllinoisensis  W.,  Productus  parvus  M.  &  W. 

(c)  Lamellibranchs.  — Kinderhook  1. :    Cardiopsis  radiata  M.  &  W.     Burlington  1. : 
Aviculopecten  Burlingtonensis  M.  &  W.,  Iowa.     Keokuk  1. :  Aviculopecten  Oweni,  A.  oblon- 
gus,  A.  amplus,  of  M.  &  W.,  111.     St.  Louis  1. :  Myalina  concentrica  M.  &.  W.,  Nucula 
Shumardana  H.,  Warsaw,  Idaho,  N.  nasuta  H.,  ibid.,  Conocardium  Meekanum  H.,  ibid. 
Chester  1. :  Pinna  Missouriensis  Swallow,  111.,  Myalina  angulata  M.  &  W.,  111.,  Schizodus 
Chesterensis  M.  &  W.,  111. 

(d)  Gastropods.  —  Kinderhook  1. :  Straparollus  lens  H.,  Goniatite  bed,  Ind.,  Bellero- 
phon  cyrtolites   H.,  ibid.      Burlington  1.  :  Platyceras  reversum   H.,  Iowa.     Keokuk  1.  : 
Pleurotomaria  Shumardi  M.  &  W.,  111.,  Platyceras  equilaterale  H.,  Iowa.     St.  Louis  1.  : 
Dentalium  venustum  M.  &  W.,  111.,  Straparollus  similis  M.  &  W.,  Spergen  Hill,  Ind., 
S.  Spergensis  H.,  ibid. 

6.  Vertebrates.  —  Fishes. — The  species  of  American  Subcarboniferous  Fishes  have 
been  described  mainly  by  Newberry,  Newberry  and  Worthen,  and  St.  John  and  Worthen 
in  the  Ohio  and  Illinois  Geol.  Reports.  The  species  described  by  Newberry  and  Worthen, 
from  Illinois  specimens,  include  16  of  Hybodonts,  26  of  Petalodonts,  52  of  Cestracionts, 
with  9  of  fin-spines  and  Psammodonts.  St.  John  and  Worthen  have  added  over  50  species 
of  Cochliodonts,  a  dozen  of  Psammodonts,  and  over  20  kinds  of  fin-spines  (III.  Geol.  Rep., 
vol.  vii.,  1883).  Fig.  1018,  tooth  of  Cochliodus  noUlis  N.  &  W.,  111.  ;  1021,  Cladodus 
spinosus  N.  &  W.,  St.  Louis  1.,  Mo.  ;  a,  section  of  the  same  ;  1020,  Carcharopsis  Wortheni 
Newb.,  Huntsville,  Ala.;  1022,  Orodus  mammillaris  N.  &  W.,  Warsaw,  111.  The  Subcarbo- 
niferous at  Ogden  has  afforded  a  tooth  of  a  species  of  Dendrodus. 

2.  CARBONIFEROUS  PERIOD. 

Since  the  Carboniferous  .period,  or  that  of  the  Coal-measures,  was  a  period 
largely  of  marshes,  as  it  opened  the  land  gradually  became  emerged;  and  the 
first  rocks  that  were  laid  down  bear  evidence,  in  many  regions,  of  the  change 
of  condition  by  their  beach-like  character.  Other  evidence  of  the  transition 
epoch  exists  in  erosions  over  the  Subcarboniferous  rocks,  making  a  surface 
of  hills  and  depressions  for  the  reception  of  the  later  depositions.  Part  of 
this  irregularity  may  be  the  work  of  denudation  before  the  Subcarboniferous 
period  had  closed;  but  other  parts  are  referred  to  the  time  of  emergence. 

ROCKS  — SUBDIVISIONS,  KINDS,   AND  DISTRIBUTION. 

The  most  prominent  subdivisions  of  the  Carboniferous  formations  are 
those  of  (1)  the  Millstone  grit,  or  the  Great  conglomerate,  named,  in  Penn- 
sylvania, the  POTTSVILLE  CONGLOMERATE;  and  (2)  the  COAL-MEASURES. 

THE  POTTSVILLE  CONGLOMERATE. 

The  conglomerate  beneath  the  coal-measures  is  generally  a  hard  gritty 
siliceous  rock,  made  of  quartzose  gravel  or  sand  —  a  rock  that  was  literally 
a  millstone  grit  early  in  the  century.  It  has  a  thickness  of  800  to  1700  feet 
in  the  center  of  the  Anthracite  region  of  Pennsylvania,  but  thins  northward 
in  this  state  to  less  than  300  feet  in  the  Wilkesbarre  region,  and  westward  to 
200-300  feet.  Its  lower  part  spreads  northward  into  western  New  York  and 
constitutes  there  the  "  Olean  conglomerate  "  of  Alleghany  and  Cattaraugus 
counties,  the  rock  of  "  Rock  City,"  25  to  60  feet  thick.  It  extends  westward 


648  HISTORICAL   GEOLOGY. 

through  Ohio,  Kentucky,  Indiana,  and  beyond ;  but  is  mostly  a  sandstone, 
where  present,  in  the  Mississippi  basin.  But  even  there,  beach-like  features 
are  often  observed.  Like  the  coal-beds  of  the  Coal-measures  the  formation 
was  only  approximately  at  a  common  level. 

In  part  of  western  Pennsylvania  the  Pottsville  conglomerate  contains 
one  or  more  coal-beds.  Just  above  the  Sharon  conglomerate,  the  base  of  the 
Pottsville  series  in  Mercer  County,  Pa.,  one  coal-bed  is  two  to  four  feet  thick, 
and  has  long  been  worked.  The  same  bed  is  mined  also  in  Ohio.  A  bed  of 
similar  character  occurs  in  the  conglomerate  of  Kentucky,  Tennessee,  and 
Alabama,  and  that  of  Alabama  affords  excellent  coal.  These  coal-beds,  with 
their  alternating  beds  of  shale,  prove  that  slow  and  varying  changes  of  level 
were  in  progress,  but  that  for  prolonged  intervals  portions  of  the  surface  lay 
quiet  until  deep  accumulations  of  vegetable  debris  had  been  made  in  the 
marshes.  The  fact  of  a  general  parallelism  in  the  movements  over  Europe 
and  America  favors  the  view  that  the  changes  in  level  and  in  deposits  were 
a  consequence,  in  a  general  way,  of  oscillations  in  the  sea  level,  that  is,  in  the 
crust  of  the  sea  bottom ;  but  at  the  same  time  there  were  other  variations 
in  level  which  were  dependent  on  local  conditions  and  movements  over  the 
continents. 

THE   COAL-MEASURES. 

The  Coal-measures  in  Pennsylvania  are  divided  into  (1)  the  LOWER  PRO- 
DUCTIVE MEASURES,  (2)  the  LOWER  BARREN  MEASURES,  (3)  the  UPPER 
PRODUCTIVE  MEASURES.  Above  the  last  there  are  the  Upper  Barren 
Measures,  corresponding  to  the  Permian. 

Over  the  great  Appalachian- Arkansas  area,  the  three  great  Carboniferous 
or  Coal-measure  regions  are,  as  shown  on  the  map,  page  412,  (1)  the 
Appalachian,  extending  from  northern  Pennsylvania  to  Alabama,  and  having 
the  Anthracite  region  as  a  detached  portion  in  eastern  Pennsylvania;  (2)  the 
Illinois-Indiana)  east  of  the  Mississippi,  extending  south  into  Kentucky; 
and  (3)  the  Iowa-Texas,  west  of  the  Mississippi. 

The  Appalachian  area  spreads  west  into  Ohio,  eastern  Kentucky,  eastern 
Tennessee,  and  northern  Alabama.  In  Tennessee,  the  Cumberland  Table- 
land has  the  Coal-measures  for  the  top,  and  a  substructure  of  Subcarbonifer- 
ous  rocks,  1000  feet  or  more  thick,  for  the  rest  of  its  height.  In  Alabama,  the 
western  portion,  constituting  the  large  Warrior  coal-fields,  is  a  continuation  of 
the  Cumberland  Measures,  with  an  extension  far  westward  nearly  to  the  Missis- 
sippi line  —  Mississippi  having  only  a  small  patch  of  Subcarboniferous  beds. 

It  is  probable  that  the  Coal-measures  of  Tennessee,  and  those  of  Alabama, 
originally  spread  across  what  is  now  the  Mississippi  valley  and  joined  the 
area  of  southern  Missouri. 

The  Carboniferous  areas  are  generally  much  broken,  especially  so  in 
Pennsylvania  and  along  the  Appalachians  to  the  southwest  of  this  state. 
The  following  map,  by  Lesley,  illustrates  in  a  general  way  the  condition  in 
Pennsylvania.  The  Anthracite  coal  is  in  narrow  isolated  strips  to  the  east- 


PALEOZOIC    TIME  —  CARBONIC. 


649 


ward,  among  upturned  rocks ;  and  the  Pittsburg  coal  at  the  west  end  of  the 
state,  although  among  nearly  horizontal  rocks,  also  has  its  outlying  patches. 
Oeological  investigation  has  proved  that  the  two  distant  areas  were  once 


1024. 


Map  of  part  of  Pennsylvania,  showing  the  coal  areas  of  the  state,  in  black;  the  Anthracite  beds  east  of  the 
Susquehanna,  and  the  Bituminous  beds  to  the  westward. 

united  and  that  the  coal  once  covered  10  times  its  present  area.  "  Broad 
Top"  in  southwestern  Pennsylvania  is  shown  by  Lesley  to  be  a  fragment  of 
the  Pittsburg  coal-bed,  about  80  square  miles  in  area,  left  in  the  general 
denudation  of  the  Appalachian  region. 

1025. 


Section  of  the  Panther  Creek  Anthracite  basin  at  Nesquehoning  tunnel. 

Figs.  1025  to  1027  represent  sections  of  portions  of  the  Anthracite  region, 
showing  the  character  of  the  flexures  that  led,  through  denudation,  to  the 
breaking  of  the  coal-beds  into  nearly  parallel  belts.  Fig.  1025  is  a  vertical 


650 


HISTORICAL   GEOLOGY, 


section  from  the  heart  of  the  Anthracite  region,  between  Nesquehoning 
Valley  on  the  west  (left  in  section),  and  Mauch  Chuuk.  It  is  from  the- 
Report  of  C.  A.  Ashburner,  of  the  Geological  Survey  of  Pennsylvania.  The 
length  is  about  1200  yards  (the  scale  of  the  figure  being  1000  feet  to  the 
inch).  The  flexures  to  the  west  have  their  summits  pushed  westward  40° 
beyond  the  vertical.  The  folded  rocks  consist  of  beds  of  Anthracite,  and 
intervening  strata  of  shale  and  sandstone ;  and  the  Anthracite  beds  include 
the  great  "Mammoth  bed"  (lettered  at  its  outcrop  E,  E,1  E2),  which  is  13 
to  27  feet  thick,  and  the  bed  F  (outcropping  at  F,1  F,2  F,3  F,4  F5),  11  to  20' 
feet  thick,  besides  one  of  eight  to  nine  feet.  The  « Mammoth  bed "  is 
doubled  on  itself  at  E1.  Fig.  1026,  from  Lesley,  is  from  the  Anthracite 

1026. 


Section  on  the  Schuylkill,  Pa.;  P,  Pottsville,  on  the  Coal-measures  (14).    Lesley. 

region  of  Pottsville,  about  30  miles  south  of  west  of  Mauch  Chunk.  All  the- 
Paleozoic  formations  from  the  bottom  of  the  Paleozoic  (2)  to  the  last,  the 
Carboniferous  (14),  are  here  flexed  together:  No.  2  being  Cambrian;  3, 
Canadian ;  4,  Trenton ;  5,  Niagara ;  7,  Lower  Helderberg ;  8,  Oriskany ; 
9,  Corniferous;  10,  Hamilton;  11,  12,  Upper  Devonian;  13,  Subcarbonifer- 
ous ;  14,  Carboniferous.  Fig.  1027,  from  H.  D.  Rogers,  in  which  the  flexures 

1027. 


Section  of  the  Coal-measures,  half  a  mile  west  of  Trevorton  Gap,  Pa.     H.  D.  Rogers. 

are  more  gentle,  is  from  Trevorton  Gap,  45  miles  west  of  Mauch  Chunk. 
The  whole  Anthracite  region  has  been  thus  upturned. 

Constitution  of  the  Coal-measures.  —  Beds  of  sandstone,  shale,  clay,  and 
limestone,  with  occasional  beds  of  coal,  and  a  bed  of  fire  clay  commonly  beneath 
the  coal-bed,  make  up  the  Coal-measures.  About  one  foot  in  40  of  the  total 
thickness  is  usually  good  coal ;  but  in  the  Upper  and  Lower  Productive 
Measures,  the  proportion  is  larger,  rising  to  one  foot  in  20. 

The  following  tables,  1  A,  1  B,  2,  3,  4,  derived  from  the  reports  of  the 
recent  Pennsylvania  Survey  (1,  2,  and  3,  by  J.  J.  Stevenson,  and  4,  by  H.  M. 
Chance)  will  give  a  general  idea  of  the  many  coal-beds  in  the  series  in 
western  Pennsylvania,  from  the  Upper  Barren  series  to  the  Lower  Productive 
Measures,  and  of  their  alternating  beds  of  sandstone,  shale,  limestone,  fire 
clay,  and  iron  ore : 


PALEOZOIC   TIME  —  CARBONIC.  651 

1.    Upper  Barren  Series,  or  Permian  Beds. 
A.    DUNKARD  CREEK   MEASURES,  GREENE   COUNTY  (SOUTHWESTERN   COUNTY  OP  PA.), 

ABOUT    700    FEET. 

Beneath  80'  of  concealed  beds  including  some  limestone  : 

Limestone  10',  sandstone  50',  limestone  4',  shale  80' 144' 

Sandstone  30',  shale  12',  limestone  2£',  sandstone  and  shale  80' 124^ 

Nineveh  coal-bed If 

Sandstone  100',  limestone  2±',  biturn.  shale  1',  sandstone  36' 139^ 

DunTcard  coal-bed 1|' 

Sandstone  and  shale  30',  limestone  3' 33' 

Limestone  2 '-5',  sandy  shale  70',  limestone  6'-15' 78'-90' 

Coal,  local  bed If 

Shale  and  iron  ore  10',  sandstone  31',  limestone  2|',  sandstone  19'-30'  62|'-73^ 

B.  WASHINGTON  GROUP,  MAXIMUM  THICKNESS  400  FEET. 

Sandstone  40',  Upper  Washington  limestone  30' 70' 

Jolleytown  coal-bed 1 

Middle  Washington  limestone  15',  sandstone  40' 65' 

Sandstone  and  shale  20',  limestone  8',  sandstone  and  shale  60' 88' 

Bituminous  shale  or  coal-bed 1' 

Lower  Washington  limestone 20' 

Washington  coal-bed 10' 

Laminated  sandstone 12' 

Little  Washington  coal-bed. ..    1' 

Limestone  20',  shale  6' 26' 

Waynesburg  "  B  "  coal-bed~. 1' 

Limestone  8',  sandstone  30' 38' 

Waynesburg  "-4"  coal-bed , 2' 

2.  Upper  Productive  Coal  Series  or  Monongahela  River  Series,  Maximum  494  feet. 

Shale  0'-12',  Waynesburg  sandstone  70' 70'-82' 

Waynesburg  main  coal-bed 6' 

Sandstone  and  shale  60',  limestone  5',  sandstone  20',  fire  clay  3'. ...  88' 

Uniontown  coal-bed l'-3' 

Sandstone  and  shale  60',  limestone  and  shale  18',  sandy  shale  40', 

limestone  and  shale  55' 173' 

Sewickley  coal-bed l'-6' 

Sandstone  and  shale  25',  limestone  18',  sandstone  10' 53' 

Redstone  coal-bed l'-6' 

Shale  0'-12',  Pittsburg  Upper  sandstone  40',  limestone  10' 50'-62' 

Pittsburg  coal-bed 5'-12' 

Fire  clay 3' 

3.  Lower  Barren  Coal-measures  (in  Westmoreland  County,  Pa.},  654 /ee£. 

Limestone  6',  shale  10'  (underneath  3'  fire  clay  and  Pittsburg  coal)  16' 

Coal-bed 1' 

Shale  10',  limestone  3',  shale  25' 38' 

Coal 1^ 

Shale  35',  Connellsville  sandstone  60'  (not  persistent),  limestone  5'  100' 

Coal-bed 1' 

Clay  9',  Morgantown  sandstone  50',  limestone  4' 63' 


652  HISTORICAL  GEOLOGY. 

Barton  coal-bed 1' 

Shale  100',  Crinoidal  limestone  4',  shale  30' 134' 

Coal-bed 2' 

Shale  and  sandstone  35',  black  limestone  4',  shale  60' 99' 

Coal-bed l'-2' 

Shale  30'-50',  with  Mahoning  sandstone  (divided  sometimes  into 
Upper,  Middle,  and  Lower),  with  thin  layers  of  shale  and  lime- 
stone, and  sometimes  a  thin  coal-bed,  in  all  195  %'  in  Ligonier 
Valley,  varying  to  75'  and  less  elsewhere 75'-195|; 

4.  Lower  Productive  Coal-measures,  or  Alleghany  River  Series,  W.  Pa. 

Freeport  Upper  coal,  E 2'-4' 

Fire  clay  2'-6',  shale  with  ore,  Freeport  Upper  limestone,  shales, 

sandstone ...    25'-40' 

Freeport  Lower  coal,  D 2'-7' 

Fire  clay  H'-4',  Freeport  Lower  limestone 42'-50' 

Kittanning  Upper  coal,  C1 H'~5' 

Fire  clay  2'-4',  Johnstown  cement-bed,  shales 2'-8' 

•Coal 0'-2' 

Fire  clay  0'-2',  shales  and  slate 30'-40' 

Kittanning  Middle  coal,  C 1 |'-3' 

Fire  clay,  shales,  sandstone 35'-40' 

Kittanning  Lower  coal,  B 3'-7' 

Fire  clay  4'-8',  sandy  shales \       sometimes       r  50'-60' 

Clarion  coal,  A >         Clarion         j        l'-2' 

Fire  clay  2 '-10',  shales *        sandstone        I  20'-30' 

BrooTffoille  coal,  A 0'-4' 

Fire  clay,  brick  clay O'-IO' 

POTTSVILLE    CONGLOMERATE. 

These  sections  show  many  alternations  of  sandstone,  limestone,  and  shale, 
with  the  several  coal-beds,  but  without  giving  the  many  minor  changes. 

Sections  from  the  Anthracite  region  afford  the  same  alternation  of  coal- 
beds  with  beds  of  sandstone  (or  conglomerate)  and  shale,  but  without  even 
thin  layers  of  limestone.  But  the  coal-beds  and  the  various  rocks  reach  a 
much  greater  thickness,  all  being  on  a  grander  scale  in  this  central  part  of 
the  Appalachian  area.  The  "  Mammoth "  coal-bed  (numbered  E  by  the 
'Geological  Survey)  attains  a  maximum  thickness  of  50  feet;  and  then,  above 
200  to  300  feet  of  sandstone x  (or  conglomerate)  and  shale  containing  two  or 
three  thin  coal  seams,  comes  the  Red  Ash  Bed  (F),  16  to  24  feet;  and  above 
another  such  interval,  a  third  great  bed  (Gr),  15  to  16  feet;  and  so  on.  But 
these  thicknesses  are  not  constant,  the  minimum  in  each  of  these  beds  in 
•other  localities  (mining  shafts)  being  half  the  above  or  less. 

The  thickness  diminishes  not  only  westward,  but  rapidly  also  northward. 
At  Carbondale,  it  is,  for  the  whole  Coal-measures,  only  300  feet,  and  for  the 
included  coal-beds  less  than  20  feet.  Near  Wilkesbarre,  the  thickness  is 
about  867  feet,  with  85  feet  of  coal-beds,  or  about  one  foot  of  coal  to  10  of 
rock.  In  the  western  Middle  Anthracite  field,  the  total  at  Hammond  is  1512 
feet,  with  83  of  coal-beds.  Near  Pottsville,  in  the  southern  field,  the  total 


PALEOZOIC    TIME  —  CARBONIC.  653 

thickness  is  3251  feet,  and  that  of  the  27  coal-beds,  154  feet,  a  ratio  of  1 : 21. 
Of  the  27  coal-beds,  numbers  19  and  20  (counting  from  below),  together  23 
feet  thick,  but  separated  by  15  feet  of  shales  —  in  all  47  feet  —  correspond  in 
position  to  the  "  Mammoth  "  bed.  The  facts  relating  to  the  Anthracite  region 
are  given  in  detail,  with  magnificent  maps  in  folio,  by  Ashburner,  in  hi& 
Report  of  the  Pennsylvania  Geological  Survey. 

The  Coal-measures  of  western  Pennsylvania  continue  to  decrease  in 
thickness  as  they  spread  northward. 

Beyond  Ohio,  in  Illinois  and  Indiana,  a  region  wholly  independent  in  its 
coal  areas,  as  shown  by  the  Ohio  and  Pennsylvania  geologists,  the  Coal- 
measures  are  less  than  1200  feet  in  thickness ;  and  a  considerable  portion 
of  the  intervening  beds  consists  of  limestone. 

The  accompanying  rocks  may  be  of  marine  origin,  brackish  water  or  fresh ; 
and  limestones  with  their  many  fossils  are  usually  marks  of  marine  origin. 

The  coal-beds  are  not  all  coal.  They  have  commonly  layers  of  shale  or 
shaly  coal  at  intervals ;  and  sometimes  so  many  that  the  bed  is  worthless. 
A  bed  may  change  in  the  course  of  a  few  miles  to  a  dirt-bed,  or  the  carbo- 
naceous material  may  wholly  fail. 

The  Pittsburg,  at  Pittsburg,  Pa.,  is  10  feet  thick;  but  it  is  made 
up  of  one  foot,  at  bottom,  of  coal  with  pyritiferous  shale ;  5  to  6  feet  of 
good  coal;  and,  above  this,  shale  and  coal,  left  as  the  roof  for  working, 
though  sometimes  including  one  or  two  feet  of  pure  coal.  It  borders  the 
Monongahela  for  a  long  distance,  the  black  horizontal  band  being  a  con- 
spicuous object  in  the  high  shores,  and  in  some  places  contains  seven  or  eight 
feet  of  good  coal.  It  extends  into  West  Virginia  and  Ohio,  over  an  area  at 
least  225  miles  by  100.  It  varies  in  thickness,  being  12  to  16  feet  in  the 
Cumberland  basin;  6  feet  at  Wheeling;  5  to  8  feet  in  Morgan,  Athens,  and 
Meigs  counties,  Ohio ;  5  to  6  feet  at  Pomeroy,  where  it  is  the  "  Pomeroy  "  bed ; 
6|-  to  91  feet  in  West  Virginia,  at  Morgantown.  But,  according  to  I.  C. 
White  (1891),  it  fails  nearly  or  wholly  to  the  southwest  of  Pennsylvania, 
over  part  of  West  Virginia  and  Ohio,  along  a  belt  north-and-south  in  course, 
and  30  to  50  miles  wide. 

Layers  of  clay -ironstone  are  often  in  the  series,  as  the  sections  show, 
making  parts  of  beds  of  limestone,  shale,  or  coal,  or  intervening  between  them ; 
and  abed  of  fire  clay  generally  underlies  a  coal-bed. 

The  coal  chiefly  of  vegetable  origin.  —  The  clay-bed  beneath  the  coal,  often 
called  the  underclay,  generally  contains  fossil  plants,  and  especially  the  roots 
or  under-water  stems  of  Lepidodendrids  and  Si gillarids,  called  Stigmarice; 
it  is  often  the  old  dirt-bed,  or  the  bed  of  earth  over  which  the  plants 
grew  that  commenced  to  form  the  coal-bed.  It  was  either  this,  or  the  clayey 
bottom  of  the  plant-bearing  marshes  or  lakes.  In  some  cases,  trunks  of  trees 
rise  from  it,  penetrating  the  coal  layer  and  rock  above  it.  The  Nova  Scotia 
coal  region  abounds  in  erect  trunks,  standing  on  the  old  "dirt-beds,"  as 
illustrated  in  Fig.  1028. 

The  rock  capping  a  coal-bed  may  be  of  any  kind,  for  the  rocks  are  the 


654 


HISTORICAL  GEOLOGY. 


result  of  whatever  circumstances  succeeded ;  but  it  is  common  to  find  great 
numbers  of  fragments  or  trunks  of  trees  and  ferns  in  the  first  stratum.  The 
shaly  beds  often  contain  the  ancient  ferns,  spread  out  between  the  layers 
with  all  the  perfection  they  have  in  an  herbarium,  and  so  abundant  that, 


1028. 


Section  of  Coal-measures  at  the  Joggins,  Nova  Scotia  (with  erect  stumps  and  stems,  a,  b,  c,  d,  in  the 
sandstone,  and  rootlets  in  the  underclays).     Dawson. 

however  thin  the  shale  be  split,  it  opens  to  view  new  impressions  of 
plants.  In  the  sandstone  layers,  broken  trunks  of  trees  sometimes  lie 
scattered  through  the  beds.  Some  of  the  logs  in  the  Ohio  Coal-measures, 
described  by  Dr.  Hildreth,  are  50  to  60  feet  long,  and  three  in  diameter.  At 
Carbondale,  in  Pennsylvania,  a  forest  of  Calamites,  or  tree-rushes,  was  cut 
through  in  opening  an  inclined  tunnel  through  sandstone  to  the  underlying 
coal-bed,  and  the  trunks,  or  rather  their  fragments,  were  so  numerous  that 
they  were  used  as  a  foundation  for  a  tramway  for  transporting  the  coal  out 
of  the  mine.  In  the  walls  crowds  of  other  stems  of  the  old  jungle  were  left. 
Lesquereux  refers  the  species  of  Calamites  to  C.  Suckovi  and  (7.  approxi- 
matus.  He  also  states  that  in  the  roof-shale  of  the  coal-bed  at  Carbondale, 
Pa.,  there  was  found  an  impression  of  the  bark  of  a  Lepidodendron,  two  feet 
wide  and  seventy-Jive  feet  long.  Andrews  mentions  that  thousands  of  the 
trunks  of  the  Fern,  Pecopteris  arborescens  Schloth.,  are  found  in  the  shale  over 
the  Pomeroy  coal-bed;  and  at  one  place  the  trunk  of  a  Sigillaria  was  traced 
by  him  for  more  than  40  feet.  In  Kentucky,  at  Paints ville,  the  stony  bottom 
of  the  river  is  an  irregular  mosaic  work  made  of  cross-sections  of  trunks 
of  Sigillaria  which  stand  crowded  together  in  the  position  of  growth 
(Lesquereux).  One  trunk  is  22  inches  across,  showing  that  the  region  was 
the  site  of  a  forest. 

Such  facts  are  common.  These  facts  are  enough  to  prove  the  vegetable 
origin  of  coal.  But  Ferns,  Lepidodendra,  and  other  plant-remains  are 
often  spread  out  in  perfection  within  the  coal-beds,  and  sometimes  in  the 
solid  masses  of  anthracite.  They  occur  also  in  the  textureless  cannel  coal, 
as  at  Breckenridge,  Ky.,  where  the  coal  "is  marked  through  its  whole  mass 
by  stems  and  leaves  of  Stigmaria  and  Lepidodendron  rendered  distinct  by 
infiltration  of  sulphuret  of  iron"  (Lesquereux).  Further,  the  coal  is  often 
penetrated  with  the  tissues  and  spores  of  the  plants.  Even  the  solid  anthra- 


PALEOZOIC   TIME CARBONIC. 


655 


cite  has  been  found  to  contain  vegetable  tissues.  On  examining  a  piece 
partly  burnt,  J.  W.  Bailey  found  that  it  was  made  up  of  carbonized 
vegetable  fibers.  Figs.  1029,  a,  b  are  from  his  paper  on  this  subject.  He 
selected  specimens  which  were  imperfectly  burnt  (like  Fig.  1029),  and  ex- 
amined the  surface  just  011  the  borders  of  the  black  portion.  Fig.  1029  a 
represents  a  number  of  ducts,  thus  brought  to  light,  as  they  appeared  when 
moderately  magnified ;  and  Fig  1029  6,  two  of  the  ducts,  more  enlarged ;  the 


1029  6. 


1029. 


Figs.  1029,  a,  6,  Vegetable  tissues  in  anthracite  ;  1030,  Spores  and  part  of  a  Sporangium,  in  bituminous  coal'of 
Ohio  (x  TO).    Figs.  1029,  Bailey  ;  1030,  Dawson. 

black  lines  being  the  coal  that  remained  after  the  partial  burning,  and  the 
light  spaces  silica.  The  ducts  were  one  tenth  of  a  millimeter  (about  four 
thousandths  of  an  inch)  broad.  Dawson  reports  like  results  from  bituminous 
coal. 

The  spores  and  sporangites,  or  spore-cases,  of  the  Lycopods  (Lepidoden- 
drids)  and  other  Acrogens,  abound  in  the  coal  to  such  an  extent  in  some 
places,  that  it  has  been  suggested  that  mineral  coal  was  made  mainly  out  of 
them.  While,  as  Dawson  has  shown,  this  inference  is  not  sustained  by  facts, 
such  spore-cases  are  very  common  in  most  coal.  Fig.  1030  represents,  much 
magnified,  the  surface  of  a  piece  of  Ohio  bituminous  coal,  showing  a  fragment 
of  a  spore-case  and  many  of  the  spores.  The  spore-cases  vary  in  size,  from 
a  tenth  to  a  hundredth  of  an  inch,  and  in  the  coal  they  often  have  an  amber- 
yellow  color.  Dr.  Dawson  states  that  he  has  a  specimen  of  Pennsylvania 
anthracite  full  of  spore-cases,  but  that  the  Pictou  coal  is  remarkably  free 
from  them. 

Animal  materials  have  also  contributed  to  the  coal,  though  sparingly. 
For  animal  decomposition  also  yields  carbonaceous  material ;  and  animal  life 
was  so  abundant  in  the  waters  that  the  contributions  in  some  places  may 
have  been  important.  The  great  number  of  fossil  fishes  in  some  very 
carbonaceous  or  bituminous  shales  has  led  to  the  suggestion  that  fish-oil  may 
have  been  the  sole  source  of  the  oil  or  gas  yielded  by  the  shales.  It  is  not 


656  HISTORICAL   GEOLOGY. 

improbable  that  it  was  a  prominent  source,  since  the  same  process  which 
will  convert  vegetable  tissues  into  coal  or  mineral  oil  (page  124),  will  pro- 
duce a  like  result  from  animal  oils. 

Equivalent  coal-beds  in  the  series.  —  Since  the  coal  marsh  area  of  Pennsyl- 
vania, eastern  Ohio,  Kentucky,  and  West  Virginia  was  in  all  probability 
essentially  continuous,  it  is  reasonable  to  look  for  the  beds  over  the  areas 
that  are  of  equivalent  age.  It  has  been  found  difficult,  however,  to  make  out 
even  the  relations  between  those  of  eastern  and  western  Pennsylvania ;  that. 
is,  of  the  Anthracite  and  Pittsburg  regions.  The  related  West  Pennsylvania, 
and  Ohio  beds  are  more  easily  correlated.  But  any  parallelism  between  the 
beds  of  Pennsylvania  and  those  of  Illinois  and  other  states  of  the  Mississippi 
valley,  unless  in  the  Lower  Coal-measures,  is  improbable. 

Coal-measures.  — Full  details  with  regard  to  the  Bituminous  Coal-measures  of  western 
Pennsylvania,  West  Virginia,  and  partly  of  Ohio,  will  be  found  in  a  Report  by  I.  C. 
White,  constituting  Bulletin  65  of  the  U.  S.  Geological  Survey.  The  following  are  facts- 
from  eastern  Pennsylvania :  — 

In  the  Panther  Creek  basin  at  Tamaqua,  where  the  total  thickness  is  2168',  the  lowest 
coal-bed  is  the  Lykens  Valley  coal,  6'  thick,  within  the  Pottsville  conglomerate.  240'  above- 
is  the  A  coal-bed,  16';  115'  higher,  the  B  coal-led,  9';  235'  higher  the  C  coal-bed,  8'  (with 
a  thin  bed  between) ;  and  then,  122'  above  the  last,  the  Mammoth  bed,  including  beds  D,, 
12',  and  E,  24',  and  another  between  of  5',  together  with  45'  and  48'  of  intervening  rock. 
211'  higher  comes  the  F,  or  Lower  Red  Ash  coal-bed,  10';  55'  higher,  the  Bony  coal-bed^ 
4,';  46'  higher,  the  G,  or  Upper  Red  Ash  coal-bed,  6';  84'  higher,  the  Washington  coal-bed,. 
3';  92'  higher,  the  Jock  coal-bed,  7';  and  then  4  coal-beds  of  2'  each  in  the  next  150';  158' 
higher,  the  First  Upper  Red  Ash  coal-bed,  4';  106'  higher,  the  Second  Upper  Red  Ash 
coal-bed,  3';  63'  higher,  the  Third  Upper  Red  Ash  coal-bed,  1'.  From  the  Mammoth  to 
the  Lykens  valley  coal-bed  the  coals  are  of  the  White  Ash  group  ;  the  remainder  are 
divided  into  the  Upper  and  Lower  Red  Ash  groups,  along  a  plane  below  the  third  coal-bed 
from  the  top. 

In  the  Pottsville  basin,  between  the  Mammoth  and  Lykens  Valley  coal-beds,  there  are 
7  coal-beds ;  and  one,  660'  above  the  Lykens,  called  the  Buck  Mountain  coal-bed,  is  8' 
thick.  The  Wilkesbarre  section  gives  widely  different  results.  In  western  Pennsylvania, 
the  Coal-measures  have  their  greatest  thickness  at  the  West  Virginia  line,  midway  in 
Greene  County,  Pa. ;  and  from  this  point  there  is  a  thinning  westward  to  about  one  third. 
Passing  into  Ohio,  the  interval  between  the  Pittsburg  and  Uniontown  coal  decreases  north- 
ward from  200'  to  60'  or  less  (Stevenson). 

The  Pottsville  conglomerate  in  Mercer  County,  Pa.,  afforded  I.  C.  White  (Pa.  Rep. 
Q,  3,  1880)  the  following  section  :  — 

Homewood  sandstone  50',  shales  5',  iron  ore  2',  limestone  2|' 59^' 

Coal,  Upper  Mercer , 2%' 

Shales  25',  iron  ore  2',  Lower  limestone  2|',  shales  10' 39£' 

Coal,  Lower  Mercer 2%' 

Shale  10',  iron  ore  1',  shales  with  Upper  Connoquenessing  sandstone..  66' 

Coal,  Quakertown 2' 

Shales,  Lower  Connoquenessing  sandstone  30',  Sharon  shales  30' 100' 

Coal,  Sharon 4' 

Fire  clay  and  shale  5',  Sharon  conglomerate  20' 25' 

The  thickness  of  the  Coal-measures  in  Ohio  is  about  1250':  the  Lower  Productive  250', 
with  7  coal-beds ;  the  Lower  Barren,  having  the  Mahoning  sandstone  at  its  base,  500'; 


PALEOZOIC   TIME  —  CARBONIC.  657 

Upper  Productive,  200';  Upper  Barren,  500',  but  much  reduced  from  the  original  thickness 
by  denudation  ;  the  total  number  of  coal-beds  is  13  ;  the  mean  thickness  of  the  lower  7  is 
4i';  of  the  upper  6,  4'.  Bed  No.  1,  called  the  Brier  Hill,  Massillon,  or  Jackson  coal,  is 
3'  to  6'  thick,  and  is  supposed  to  be  No.  A  of  the  Pittsburg  section  ;  No.  6,  the  Upper 
Freeport,  3'  to  12'  thick  ;  No.  8,  4'  to  8'  thick,  the  Pittsburg  coal-bed,  at  the  top  of  the 
Lower  Barren  Measures ;  and  No.  11, 1|'  to  4'  thick,  the  Waynesburg  coal-bed  (Newberry). 

In  Indiana,  the  Coal-measures  cover  an  area  of  about  7000  square  miles  over  the 
western  part  of  the  state,  are  800'  to  1000'  thick,  and  include  10  coal-beds  varying  from 
1'  to  11'  in  thickness  (Collett). 

In  Illinois,  the  total  thickness  is  600'  to  1000',  and  the  number  of  workable  coal-beds 
6,  and  of  other  thin  seams,  6.  The  thickness  of  the  former  is  nearly  20'  (Worthen). 
Near  Morris,  and  elsewhere,  in  northeastern  Illinois,  there  is  a  single  bed  of  coal  with  clay 
&bove  and  below.  Four  miles  to  the  southeast  of  Morris,  sandy  shales  of  the  Coal-measures 
contain  concretions  which  have  made  the  place  famous  because  of  the  many  kinds  of 
Ferns,  Insects,  Spiders,  Myriapods,  rare  Crustaceans,  and  even  Amphibians,  which  have 
been  found  in  the  concretions  —  the  specimens  having  been  in  many  cases  the  nuclei. 
No  marine  fauna  has  been  found  in  them. 

In  southwestern  Kentucky,  the  Coal-measures  north  of  Pine  Mountain  are  1650'  thick, 
and  contain  9  workable  beds  of  coal ;  and  farther  east  they  are  still  thicker. 

The  Coal-measures  spread  northwestward  over  southwestern  Iowa,  where  they  have  a 
maximum  thickness  of  600',  and  a  thickness  of  coal-beds  of  about  8',  as  in  Illinois.  The 
Coal-measures  extend  northward  beyond  the  limits  of  the  upper  beds  of  the  Subcarbonif- 
erous  limestone.  At  Davenport,  on  the  Mississippi,  a  boring  found  a  thickness  of  30',  and 
the  beds  resting  on  the  Devonian  Corniferous  limestone. 

In  Arkansas,  the  area  of  the  Coal-measures  is  about  1000  square  miles,  and  the  mean 
thickness  of  the  coal-beds  is  estimated  at  3'. 

The  isolated  coal  area  of  Michigan  covers  about  6700  square  miles,  and  the  beds  have 
a  thickness  of  300'  or  less.  At  East  Saginaw,  this  300'  includes  the  underlying  Parma 
white  sandstone  105',  and  the  overlying  Woodville  brown  sandstone  79  feet ;  and  in  the 
intermediate  shales  and  sandstone  there  is  one  bed  of  coal  3'  to  4'  thick  (Winchell). 

In  Alabama,  the  Coal-measures  cover  5500  square  miles.  There  are  3  areas,  —  the 
Warrior,  the  Cahaba,  and  the  Coosa.  The  first  contains  nine  tenths  of  the  whole  area. 
The  thickness  near  Tuscaloosa,  where  the  beds  disappear  beneath  more  recent  formations, 
is  about  3000'.  The  number  of  coal  seams  is  about  35,  of  which  15  are  over  2£'  thick,  and 
6,  of  4'  and  over.  The  beds  become  thinner  to  the  northwest.  The  lowest  of  the  coal-beds 
are  those  in  the  Pottsville  conglomerate. 

The  Rhode  Island  Carboniferous  covers  the  most  of  the  southern  part  of  the  state,  and 
extends  northward,  through  Providence,  to  the  northern  border:  there  it  passes  into 
Norfolk  County,  Mass.,  and  thence  eastward,  through  Bristol  County,  to  Plymouth 
County.  The  exact  limits,  east,  west,  and  north,  have  not  been  made  out,  the  stratifica- 
tion of  the  rocks  being  much  obscured  by  displacements  or  flexures  and  metamorphism. 
There  are  conglomerates  and  slates  which  are  supposed  by  Hitchcock  and  Jackson  to  be  a 
part  of  the  formation.  The  quartzose  conglomerate  outcrops  at  Newport  and  elsewhere, 
and  forms  a  bold  feature  in  the  landscape  at  "  Purgatory,"  2£  miles  east  of  Newport,  and 
at  the  "Hanging  Rocks."  The  stones  vary  in  size  from  an  inch  to  a  foot  or  more. 
Associated  with  the  slate  there  are  beds  of  limestone. 

The  principal  points  where  coal  outcrops  are  near  Providence,  Cranston,  Bristol, 
Portsmouth,  Valley  Falls,  Cumberland,  and  Newport  (a  thin  bed  outcropping  on  the  coast) , 
in  Rhode  Island ;  and  in  Raynham,  Wrentham,  Foxboro,  and  Mansfield,  in  Massachu- 
setts. The  beds  are  much  broken  and  very  irregular  in  thickness,  owing  to  the  upturning 
and  flexures  the  formation  has  experienced,  and  the  coal  is  an  exceedingly  hard  anthra- 
cite, because  of  the  metamorphism,  and  to  some  extent  is  graphitic.  Still,  the  slates  often 
contain  fossil  plants,  part  of  which  are  identical  in  species  with  those  of  Pennsylvania. 
DANA'S  MANUAL  —  42 


658  HISTORICAL   GEOLOGY. 

Near  Portsmouth,  at  Aquidneck,  three  beds  are  reported  to  exist,  2'  to  20'  thick,  and  at 
Case's,  one  of  the  three  is  13'  thick ;  at  Providence,  one,  of  10';  at  Valley  Falls,  five,  6'  to 
9';  at  Cumberland,  two,  15'  to  23';  near  Mansfield,  several,  with  the  maximum  thickness 
10'.  The  earliest  opening  was  made  at  Case's,  near  Portsmouth,  in  1808. 

At  Worcester,  Mass. ,  an  independent  coal  area,  there  are  mica  schists  and  graphitic 
slate,  with  remains  of  a  species  of  Lepidodendron. 

Cape  Breton,  Nova  Scotia,  New  Brunswick.  —  A  large  part  of  Cape  Breton  and  the 
northern  half  of  Nova  Scotia,  and  more  than  two  thirds  of  New  Brunswick,  are  covered  by 
the  coal  formation.  The  chief  of  the  coal  mines  are  in  Nova  Scotia,  in  the  Pictou, 
Colchester,  and  Cumberland  districts.  In  New  Brunswick,  the  formation  is  thin  and 
yields  little  coal.  At  the  Joggins,  in  the  Cumberland  district,  the  beds,  according  to 
Dawson,  rest  on  3000'  of  Subcarbonif  erous  beds,  have  a  thickness  of  13,000',  and  are  made 
up  of  sandstone,  conglomerates,  shales,  and  impure  limestone.  Of  the  whole,  5000'  to  6000' 
pertain  to  the  conglomerate  or  Millstone  grit,  4000'  to  the  Lower  Coal-measures,  and  3000' 
to  the  Upper,  a  large  portion  of  which  is  regarded  by  Dawson,  on  account  of  the  fossils,  as 
Permian.  In  the  series,  there  are  76  dirt-beds  and  coal-seams,  indicating  as  many  levels 
of  verdant  fields  or  marshes.  Each  dirt-bed  is  a  clayey  layer  with  stumps  of  StigmarisB 
and  other  plant  remains  ;  but  only  15  contain  any  coal.  The  main  coal-bed  at  the  Joggins 
is  only  5'  thick,  with  a  foot  or  so  of  clay  along  the  middle.  The  Permian  at  Pictou  has  a 
thickness,  according  to  Fletcher,  of  1146',  but  on  John  River,  near  the  boundary  of  the 
Colchester  district,  8107'.  For  a  detailed  report  on  the  Pictou  and  Colchester  districts, 
by  Fletcher,  see  Can.  Geol.  Rep.  for  1890-91. 

The  Millstone-grit  portion  includes  thick  beds  of  coarse  gray  sandstones,  containing 
prostrate  trunks  of  Coniferous  trees  in  its  upper  and  middle  parts,  with  red  and  com- 
paratively soft  beds  in  its  lower ;  many  layers  of  coaly  shale  occur  throughout,  but  no 
coal-beds.  At  Pictou,  where  the  beds  dip  20°  or  more,  the  mean  thickness  of  the  main 
coal-bed  is  38';  of  another,  159'  below,  15£' ;  and  280'  below  this  occurs  the  McGregor 
seam  12'  thick.  The  total  thickness  of  the  Carbonifererous  is  about  the  same  as  at  the 
Joggins  (Dawson). 

A  Carboniferous  formation  without  coal  is  the  great  fact  for  the  western  half  of  the 
continent.  Beyond  the  Mississippi,  near  the  meridians  of  97°  to  101°  W.,  the  formation, 
as  it  extends  westward,  becomes  increasingly  thinner  in  its  coal-beds  and  passes  beneath 
the  Triassic,  Cretaceous,  and  Tertiary  beds  of  the  eastern  Rocky  Mountain  slope.  The 
formation  makes  its  first  reappearance  at  the  surface  at  about  104°  W.,  in  the  Black  Hills 
of  Dakota ;  but  it  comes  up  destitute  of  coal,  and  is  a  limestone  formation  400'  thick, 
including  a  middle  portion  of  sandstone,  75'  thick.  Moreover,  through  the  region  of  the 
Rocky  Mountains  farther  west,  and  also  northward  through  British  America,  wherever  the 
Carboniferous  is  to  be  seen,  the  rock  is  a  barren  limestone,  or  limestone  and  sandstone. 
It  is  widely  distributed  as  a  surface  rock  at  the  base  of  Archaean  ridges  and  elsewhere,  has 
its  largest  continuous  area  in  Arizona,  is  widely  distributed  over  the  Great  Basin  in  Nevada, 
occurs  also  in  Utah  and  Montana,  whence  it  extends  northward  beyond  the  United 
States  boundary  along  the  summit  region  of  the  mountains.  The  deposition  of  Mesozoic, 
Cenozoic,  and  lacustrine  beds,  and  the  extensive  ejection  of  igneous  rocks  over  the  vast 
region  of  the  United  States,  between  the  meridian  of  105°  W.  and  the  Pacific,  have  left  little 
of  the  Paleozoic  formations  in  sight.  Along  the  summit  region  the  beds  rest  on  Silurian 
or  Cambrian  beds. 

The  Carboniferous  is  the  surface  rock  at  the  Grand  Canon  of  the  Colorado.  It  there 
comprises  the  Aubrey  limestone,  as  the  summit  portion  of  the  lofty  walls,  835'  thick ; 
below  this,  the  Aubrey  sandstone,  often  having  cross-bedded  layers  for  1455';  and  then 
the  "  Red- wall "  limestone,  having  a  thickness  of  970'  ( Walcott),  in  all  3260'.  The  lime- 
stones are  more  or  less  cherty  and  in  part  shaly  or  arenaceous,  and  the  upper  contains 
some  gypsum.  A  portion  of  the  lower  limestone,  of  undetermined  thickness,  contains 
Subcarbonif  erous  fossils. 


PALEOZOIC   TIME  —  CARBONIC.  659 

In  the  Wasatch,  the  Carboniferous  beds  are  about  13,000'  thick,  the  Upper  Coal- 
measure  limestone  2000'  thick ;  below  this  is  the  Weber  quartzyte,  6000';  and  then  5000' 
of  the  Wasatch  limestone,  the  lower  part  of  which  contains  Subcarbonif erous  fossils.  The 
Carboniferous  formation  in  the  Eureka  basin,  Nevada,  has  a  total  thickness  not  far  from 
10,000',  of  which  the  Weber  conglomerate  comprises  2000',  and  a  quartzyte  at  the  base, 
3000'.  The  upper  member  is  only  500'  thick,  but  has  a  thickness  of  2000'  to  the  north- 
west. (Hague.) 

In  California,  Carboniferous  beds,  consisting  partly  of  limestone,  occur  in  the  Sierra 
Nevada  along  a  broad  belt  west  of,  and  nearly  parallel  to,  its  axis.  They  extend  inter- 
ruptedly, says  Whitney  (1866),  from  Shasta  County,  near  Pitt  River  (40°  45'  N.  where 
limestone  of  the  period  was  first  identified  by  Trask  in  1855)  through  Plumas  County, 
southwestward,  to  the  Tahichipi  valley,  more  than  500  miles.  The  limestone  occurs  at 
intervals  interstratified  with  the  argillyte,  mica  schist,  and  siliceous  slates  of  the  auriferous 
series,  and  disappears  at  times,  as  Whitney  states,  by  graduating  into  calcareous  sand- 
stones and  the  siliceous  slate.  The  fossils  obtained  by  Trask  near  Bass  Ranch,  comprising 
species  of  Fusulina  (Fig.  1069),  a  Lithostrotion  hardly  distinguishable  from  L.  mammillare, 
and  other  kinds,  were  referred  by  Meek,  with  much  expressed  doubt,  to  the  Subcarbo- 
nif erous;  and  Gabb  suggested  the  same  conclusion  for  the  fossils  of  the  limestone  at 
Pence's  Ranch,  80  miles  to  the  southeastward.  H.  W.  Turner  reports  Fusulina  from 
Kite's  Cove,  Mariposa  County,  and,  from  other  parts  of  the  same  interrupted  limestone 
belt,  in  Calaveras  and  Amador  counties,  and  at  different  points  in  Plumas  County.  It  is 
probable  that  the  rocks  are  partly  at  least  of  the  Carboniferous  period. 

Carboniferous  rocks  occur  also  in  the  Klamath  Mountains  and  Coast  Range,  according 
to  Fairbanks  and  Diller.  But  they  have  not  yet  been  identified  in  Oregon  and  Washington. 
They  exist  in  British  Columbia,  in  some  parts  of  the  Coast  region,  and  are  extensively 
distributed  over  the  interior  plateau,  extending  northward  as  far  at  least  as  the  Peace 
River  region,  in  latitude  55°-56°  N. 

In  the  Arctic  regions,  Carboniferous  beds  are  reported  from  Melville  Island,  at  Cape 
Dundas,  Bridgeport  Inlet  and  Skene  Bay  ;  Baring  Island  at  Cape  Hamilton  ;  Byam  Martin 
Island  ;  and  on  Bathurst  at  Schomberg  Point  and  Graham  Moore  Bay.  The  line  of  outcrops 
of  the  beds  runs  E.N.E.  They  are  accompanied  by  clay  ironstone  in  nodules,  as  is  usual 
in  coal  regions  (Haughtoii).  For  notes  on  the  Carboniferous  areas  of  the  Arctic  regions, 
see,  further,  G.  M.  Dawson,  Hep.  Geol.  Canada,  for  1886. 

In  Mexico,  Carboniferous  limestone,  representing  the  Carboniferous  period,  or  the 
Carboniferous  and  Permian  periods,  has  been  observed  in  some  of  the  ridges  and  mountains 
of  Coahuila  and  Nuevo  Leon  (Frazer  and  Hall),  and  also  on  the  borders  of  Mexico  and 
Guatemala ;  also,  in  Nicaragua,  with  overlying  Permian  and  underlying  Silurian  and 
Devonian  (Crawford,  1890). 

In  South  America,  the  Carboniferous  beds  have  great  extent  in  Brazil,  in  the 
Amazon  valley, —  as  great  as  the  North  American  Carboniferous, —  but  they  afford  no 
coal  (Derby,  Am.  Jour.  Sc.,  xvii.,  1879). 

The  following  probable  correlations  are  based  by  Lesquereux  on  the  distribution  of  the 
species  of  coal-plants  :  — 

Coal  A,  which  exists  within  the  Pottsville  conglomerate,  or  Millstone  grit,  at  the  basis 
of  the  Coal-measures,  or  its  equivalent  plant- bearing  beds :  at  Shamokin,  Lehigh  Summit, 
lower  bed  at  Trevorton,  Broad  Top,  in  Pennsylvania  ;  at  Massillon,  Ohio  ;  at  Union  Mines, 
in  Crittenden  County,  Kentucky. 

Coal  B,  Archbald,  Pa. ;  Spring  Creek,  Ind. ;  Union,  Greenup,  and  Carter  counties, 
Ky.  ;  Murphysboro,  Mazon  Creek,  Morris,  111.,  in  shale  over  coal. 

Coal  B  or  C,  Carbondale,  Pa.  ;  Cannelton,  Pa. ;  Clinton,  Mo. 

Coal  C,  Archbald,  Shamokin,  Pittston,  at  Boston  mine,  etc.  ;  Eugene,  Vermilion 
County,  Ind. 


660  HISTORICAL   GEOLOGY. 

Coal  D,  Carbon  Hill,  Pittston,  Pa. ;  Vermilion  County,  Ind.  ;  Duquoin  and  St.  John, 
111. 

Coal  D  or  E,  Sullivan  County,  Ind.  ;  Hopkins  and  Christian  counties,  Ky. 

Coal  E,  Mammoth  bed  at  Pottsville,  Pittston,  Yatesville,  Pa.  ;  Nelsonville  and  Cosh- 
octon,  Ohio ;  Stark  and  Peoria  counties,  111. 

Coal  E  and  F,  Wilkesbarre,  Pa.  ;  Nelsonville  and  Coshocton,  Ohio. 

Coal  F,  Plymouth,  Pittston,  and  Maltby,  Pa. 

Coal  G,  Olyphant,  Plainsville,  Gate  and  Salem  veins,  Pottsville,  Pa. ;  Pomeroy,  Ohio. 

At  Cannelton,  Pa.,  the  number  of  species  of  plants  obtained  from  the  coal-bed  of  the 
B  or  C  horizon,  according  to  Lesquereux,  is  140 ;  at  Mazon  Creek,  111.,  from  the 
bottom  of  the  coal-bed  B,  150  species,  and  adding  those  from  the  overlying  clay-bed,  200 
species  ;  and  if  the  species  from  the  same  bed  at  Murphysboro  be  added,  with  others 
the  bed  affords  in  Missouri,  the  number  mounts  up  to  250  species,  which  is  a  very  large 
flora  for  one  coal-bed  level.  The  whole  number  of  plants  thus  far  described  from  the 
American  Coal-measures,  the  Permian  portion  included,  is  900. 


3.  PERMIAN  PERIOD. 
ROCKS  — KINDS  AND  DISTRIBUTION. 

It  has  been  stated  that  the  Upper  Barren  Measures  of  Pennsylvania  and 
West  Virginia,  having  a  thickness  in  Monongalia*  County  of  1044  feet,  were 
of  the  age  of  the  Permian  period,  though  continuous  in  bedding  with  the 
strata  below.  Similarly,  the  upper  beds  —  clayey  beds,  sandstones,  with  some 
impure  limestones  —  in  the  Coal-measures  of  Kansas,  Missouri,  Illinois, 
Nebraska,  and  Texas,  are  referred  to  the  Permian.  The  same  is  true  for  an 
upper  part  of  the  Coal-measures  of  Nova  Scotia,  New  Brunswick,  and  Prince 
Edward  Island.  The  evidence  of  Permian  age  consists  in  the  presence  of 
remains  of  plants,  Mollusks  and  Vertebrates,  like  those  of  the  foreign 
Permian.  Permian  beds  have  also  been  identified  in  the  region  of  the 
Colorado  Canon  in  Arizona  and  Utah,  where  845  feet  of  limestone  and  shales 
containing  gypsum,  overlying  Carboniferous  limestone,  are  referred  to  this 
period.  In  the  Wasatch,  the  beds  have  a  thickness  of  600  feet. 

Permian  beds  were  identified  in  the  San  Francisco  Mountains  by  Marcou  in  1853  ;  and 
in  the  Guadalupe  Mountains,  New  Mexico  (a  white  limestone),  by  B.  F.  Shumard  in  1858. 
About  the  Colorado  Canon  they  have  been  studied  by  Walcott  (in  1880)  and  others.  The 
rock  in  the  Wasatch  is  the  "  Bellerophon  limestone  "  described  by  King  (1878).  Permian 
was  identified  in  Nova  Scotia  by  Dawson  in  1845  ;  in  Kansas,  by  Meek,  Swallow  and 
Hawn,  in  1858 ;  in  Illinois,  by  Worthen,  in  1858 ;  and  soon  after  in  Missouri  and 
Nebraska  by  Meek  ;  in  Pennsylvania  and  West  Virginia,  by  Fontaine  and  I.  C.  White,  in 
1880.  Cope's  observations  in  Illinois  and  Texas  were  made  in  1875,  and  later;  C.  A. 
White's,  in  Texas,  in  1889.  On  the  Kansas  Permian,  see,  further,  Prosser's  paper  of  1894. 

The  Texas  Permian  occupies  the  western  portion  of  the  Carboniferous  area.  North  of 
the  Brazos  River  the  lower  beds,  in  the  Wichita^of  Cummins,  are  red  clays  and  sand- 
stones, with  some  impure  limestone  at  top.  The  fossils  described  by  C.  A.  White  are 
from  this  part  of  the  series,  and  so  also  the  Vertebrates  described  by  Cope.  Above  are 
the  so-called  Clear-Fork  and  Double  Mountain  division,  and  then  come  the  Dockum 
beds,  different  in  rocks  and  fossils,  which  are  referred  to  the  Triassic. 


PALEOZOIC    TIME CARBONIC.  661 

ECONOMICAL   PRODUCTS. 

Coals,  Iron  Ores,  Clays,  and  Salt  of  the  Carboniferous  and  Subcarboniferous 

Formations. 

1.  Coal.  —  Coal  occurs  of  three  kinds:  (1)  Anthracite,  or  stone  coal;  (2) 
ordinary  Bituminous,  sometimes  distinguished  as  "  cubical  coal,"  in  view  of  its 
natural  fracture ;  and  (3)  Cannel  coal,  the  dull  textureless  bituminous  coal, 
breaking  irregularly,  with  a  conchoidal  fracture,  and  only  occasionally  con- 
stituting parts  of  coal-beds.  Excepting  the  cannel,  the  coals  have  distinctly, 
on  a  cross-fracture,  a  faint  banding,  due  to  a  straticulate  structure  or  bedding, 
and  are  rarely  laminated  unless  very  impure.  The  blocks  into  which  bitumi- 
nous coals  break  have  probably  been  made  by  the  strains  to  which  the  coal- 
bed  had  been  subjected ;  they  are  not  those  of  crystallization. 

The  bituminous  coals  which  soften  in  the  fire  and  cake  over  are  called 
caking  or  cementing  coal ;  and  those  which  burn  without  caking,  the  open- 
burning  coals.  The  "  Block  coal "  of  Ohio,  Indiana,  and  the  neighboring 
states,  is  of  the  non-caking  kind,  that  most  convenient  for  furnaces  and  open 
fires.  The  caking  coals  are  prepared  for  metallurgical  purposes  by  conversion 
into  coke  by  partial  combustion  under  cover  (in  ovens),  which  drives  off  the 
volatile  matter.  In  the  best  process  there  is  a  loss  usually  of  20  to  35  per 
cent  of  weight,  and  an  increase  in  bulk  and  hardness.  At  the  same  time  the 
coal  loses  about  half  its  sulphur. 

The  first  of  the  following  tables  gives  the  results  of  analyses  of  coals,  and 
also  of  peat,  showing  the  amount  of  the  several  constituents ;  and  the 
second,  the  amount  of  fixed  carbon,  and  of  volatile  hydrocarbons  (gas,  oil) 
afforded,  and  besides,  the  water  and  ash,  or  impurities. 

The  flame  given  out  in  a  fire  is  that  of  the  burning  gas  as  it  escapes. 
This  gas  is  almost  wholly  a  compound  of  carbon  and  hydrogen,  or  a  hydro- 
carbon ;  but  it  includes  a  little  carbonic  oxide  (carbon  monoxide),  which  has  a 
bluish  flame ;  and  in  the  case  of  anthracites,  which  have  very  little  volatile 
matter  apart  from  the  moisture,  this  gas  is  the  chief  one.  But  anthracites 
shade  down  into  the  semi-bituminous,  and  the  flame  varies  consequently 
from  bluish  to  yellow. 

Cannel  coal  (called  in  Scotland  Parrot  coal)  affords  usually  the  most 
volatile  hydrocarbons,  and  is  valuable  for  gas  making ;  and  it  will  be  much 
used  for  its  yield  of  mineral  oil  or  petroleum  whenever  the  oil-wells  give  out. 
It  occurs  in  Ohio  and  Indiana,  and  still  more  abundantly  in  eastern  Ken- 
tucky, where  Breckenridge  is  a  noted  locality.  The  amount  of  impurity  in 
them  is  often  large,  and  the  beds  frequently  contain  remains  of  Fishes, 
Crustaceans,  and  some  other  fossils,  which  is  not  true  of  the  ordinary  bitumi- 
nous coal.  The  fossils  appear  to  be  almost  solely  those  of  fresh  waters. 
Linton,  Ohio,  is  a  locality  famous  for  its  Fishes  and  Amphibians,  its  cannel 
coal  affording  50  species  or  more. 

The  Subcarboniferous  beds  of  New  Brunswick,  in  some  parts  of  King's, 
Albert,  and  Westmoreland  counties,  afford  a  semi-asphaltic  material  called 


662 


HISTORICAL   GEOLOGY. 


albertite,  looking  like  bitumen  or  asphalt,  but  not  readily  fusing  like  it  in  a 
candle.  It  occupies  rents  in  the  rock,  instead  of  constituting  layers.  A 
similar  substance,  called  grahamite,  occurs  under  similar  conditions  in  the 
Coal-measures  of  West  Virginia,  20  miles  south  of  Parkersburg.  It  is  partly 
columnar  in  fracture  at  right  angles  to  the  walls  of  the  vein.  Both  are  sup- 
posed to  have  been  made  from  the  oxidation  of  mineral  oil. 


1 

Anthracite,  Pennsylvania  

Carbon 
90-45 

Hydr. 
2-43 

Ox. 
2-45 

Nitr. 

Sulph. 

Ash 
4-67, 

Analysts 
Regnault. 

2 

Anthracite,  Pennsylvania  

92-59 

2-63 

1-61 

0-92 

2-25, 

Percy. 

Anthracite  South  Wales 

92-56 

3-33 

2-53 

1-58, 

Regnault* 

4 

Caking  Coal   Kentucky 

74-45 

4-93 

13-08 

1-03 

0-91 

5-00 

Peters 

5. 
6 

Caking  Coal,  Nelsonville,  Ohio  .  . 
Caking  Coal,  South  Wales.. 

73-80 
82-56 

5-79 
5-36 

16-58 
8-22 

1-52 
1-65 

0-41 
0-75 

1-90, 
1-46, 

Wormley. 
Noad. 

7. 
8 

Caking  Coal,  Northumberland  .  . 
Non-caking,  Kentucky  

78-69 

77-89 

6-00 
5-42 

10-07 
12-57 

2-37 
1-82 

1-51 
3-00 

1-36, 
2-00, 

Tookey. 

Peters. 

9. 
10. 
11. 
1?, 

Non-caking,  "Block  Coal,"  Ind. 
Non-caking,  Brier  Hill,  Ohio.  .  .  . 
Non-caking,  S.  Staffordshire  .... 
Non-caking  Scotland  

82-70 
78-94 
76-40 
76-08 

4-77 
5-92 
4-62 
5-31 

9-39 
11-50 
17-43 
13-33 

1-62 
1-58 

2-09 

0-45 
0-56 
0-55 
1-23 

1-07, 
1-45, 
1-55, 
1-96, 

Cox. 
Wormley. 
Dick. 

Rowney. 

13 

Cannel  Coal,  Breckenridge  .    . 

68-13 

6-49 

5-83 

2-27 

2-48 

12-30 

Peters. 

14 

Cannel  Coal   Wigan 

80-07 

5-53 

8-10 

2-12 

1-50 

2-70 

V~aux 

15. 
1f> 

Cannel  Coal,  "  Torbanite  "  
Bituminous  Coal,  Wyoming  .  .  . 

64-02 
73-55 

8-90 
4-17 

5-66 
17-20 

0-55 
1-93 

0-50 
1-18 

20-32, 
1-86, 

Anderson. 

17, 

Bituminous  Coal,  Wyoming. 

75-20 

4-74 

10-37 

1-37 

I'll 

7-20, 

18 

Albertite  Nova  Scotia 

86-04 

8-96 

1-97 

2-93 

0-10 

Wetherell 

19 

Brown  Coal,  Bovey  

66-31 

5-63 

22-86 

0-57 

2-36 

2-27, 

Vaux. 

flO 

Brown  Coal,  Wittenberg  ... 

64-07 

5-03 

27-55 

3-35, 

Baer. 

21. 

Peat,  light  brown  (imperfect).  .  . 
Peat,  dark  brown  

50-86 
59-47 

5-80 
6-52 

42-57 
31-51 

0-77 
2-51 

— 

Websky. 
Websky. 

7!3 

Peat,  black  

59-70 

5-70 

33  O4 

1-56 

Websky. 

24. 

Peat,  black.. 

59-71 

5-27 

32-07 

2-59 

Webskv. 

No.  13,  the  Breckenridge  cannel,  of  Hancock  County,  Ky.,  consists,  when  the  ash  is 
excluded,  of  carbon  82-36,  hydrogen  7-84,  oxygen  7-05,  nitrogen  2-75 ;  and  the  Bog-head 
cannel  of  Scotland,  called  also  torbanite,  contains  carbon  80-39,  hydrogen  11-19,  oxygen 
7-11,  nitrogen  and  sulphur  1-31. 

The  "Mineral  charcoal  "  differs  little  in  composition  from  ordinary  bituminous  coal ; 
there  is  less  hydrogen  and  oxygen.  Rowney  obtained,  for  that  of  Glasgow  and  Fifeshire, 
carbon  82-97,  74-71,  hydrogen  3-34,  2-74,  oxygen  7-59,  7-67,  ash  6-08,  14-86.  The 
nitrogen  is  included  with  the  oxygen  ;  it  amounted  to  0-75  per  cent  in  the  Glasgow  charcoal. 
Exclusive  of  the  ash,  the  composition  is,  carbon  88-36,  87-78,  hydrogen  3-56,  3-21,  oxygen 
and  nitrogen  7-28,  9-01. 

The  oxygen  in  a  coal,  which,  as  the  table  shows,  varies  from  about  10  pounds  to  15  in 
a  hundred  in  the  ordinary  bituminous  coals,  is  so  much  waste  material  as  far  as  the 
heating  purposes  of  the  coal  are  concerned,  because  the  atmosphere  is  at  hand  to  supply 
all  that  combustion  requires.  The  moisture  also  causes  loss  of  heat,  because  of  the 
amount  required  to  evaporate  and  expel  it. 

The  following  are  other  analyses  of  anthracite  and  bituminous  coal ;  they  are  a  few 
from  the  many  by  McCreath,  of  the  Pennsylvania  Geological  Survey.  The  amount  of 
volatile  hydrocarbons  is  given  in  the  second  column. 


PALEOZOIC   TIME  —  CARBONIC. 


663 


8p.gr. 

Anthracite,  Mammoth 1-617 

«         1-631 

1-575 

Bituminous,  Waynesburg 


Pittsburg. 


Freeport  Upper, 


Kittanning  Upper , 


Vol. 

Fixed 
Carbon 

Sulphur 

Water 

Ash 

3-08 

86-38 

0-50 

4-12 

5-92 

4-27 

83-81 

0-64 

3-09 

8-18 

4-38 

83-27 

0-73 

3-42 

8-20 

38-30 

48-97 

2-73 

1-04 

8-97 

34-68 

49-59 

1-27 

1-27 

13-19 

37-74 

54-56 

1-50 

1-73 

4-47 

25-20 

65-52 

2-25 

1-27 

5-76 

37-22 

56-01 

0-98 

1-04 

4-15 

29-68 

63-77 

1-72 

0-70 

4-13 

25-77 

70-22 

0-62 

0-80 

2-59 

23-91 

64-53 

4-79 

0-77 

6-00 

39-22 

55-69 

0-57 

2-71 

1-81 

It  is  found  that  the  Pittsburg  coal  affords  0*0011  to  0-1248  per  cent  of  phosphorus, 
which  becomes  0-0018  to  0-2003  in  the  coke.  Other  analyses  are  given  in  the  Geological 
Reports  of  Ohio,  Kentucky,  Indiana,  Illinois,  etc.  It  is  useless  to  cite  further  from  them, 
since  the  variation  is  very  large  in  a  single  bed  as  it  is  traced  over  the  country,  and  the 
state  reports  should  be  referred  to  for  details. 

The  Arctic  coal,  of  Grinnell  Land  (81°  43'  N.  and  64°  4'  W.),  is  good  caking  bituminous 
coal ;  it  afforded  R.  J.  Moss,  on  analysis,  carbon  75-49,  hydrogen  5-60,  oxygen  and 
nitrogen  9-89,  sulphur  0-52,  ash  6-49,  water  2-01  =  100  (Proc.  R.  Dublin  Soc.,  1878). 

The  ordinary  impurities  of  coal,  making  up  its  ash,  are  silica,  a  little  pot- 
ash and  soda,  and  sometimes  alumina,  with  often  oxide  of  iron,  derived 
usually  from  sulphide  of  iron  (pyrite  or  marcasite),  besides,  in  the  less  pure 
kinds,  more  or  less  clay  or  shale.  The  amount  of  ash  in  the  selected  coal 
does  not  ordinarily  exceed  10  per  cent,  but  it  is  sometimes  30  per  cent ;  and 
rarely  it  is  less  than  2  per  cent.  Thin  layers  of  pyrite  are  rather  common, 
and  occasionally  a  bed  of  other  ores  of  iron  is  intercalated. 

Wormley  gives  the  following  analyses  (besides  others)  of  the  ash  of  two  coals,  one 
from  the  Youghiogheny,  in  western  Pennsylvania,  and  the  second  from  Pigeon  Creek, 
Jackson  County,  Ohio  :  Silica  49-10,  37-40,  alumina  38-60,  40-77,  sesquioxide  of  iron  3-68, 
9-73,  magnesia  0-16,  1-60,  lime  4-53,  6-27,  potash  and  soda  1-10, 1-29,  phosphoric  acid  2-23, 
0-51,  sulphuric  acid  0-07,  1-99,  sulphur  (combined)  0-14,  0-08,  chlorine  «race=99-61,  99-64. 
The  fact  that  there  is  too  much  sulphur  in  the  Ohio  coals  for  combination  with  the  iron 
present  is  shown  in  the  following  table,  containing  some  of  his  results :  — 

Sulphur  in  the  coals 0-57          1-18          2-00          0-91          0-86 

Iron  in  the  coals 0-075        0-742        0-425        0-122        0.052 

Sulphur  required  by  the  iron. ..     0-086        0-848        0-486        0-139        0-06 

The  source  of  the  impurities  is  in  part  the  vegetation  of  which  the  coal  was  made, 
which  is  shown  on  page  74  to  be  sometimes  large,  even  as  regards  silica  and  alumina,  the 
constituents  of  a  clay,  and  large  also  for  calcium  carbonate  and  potash. 

According  to  the  average  composition  of  Lycopods,  the  dried  plant  affords  5  pounds 
of  ash  to  100  of  the  plant,  and  40  per  cent  of  this  is  alumina  and  silica  (27  alumina  and  13 
silica) ,  and  hence  these  two  ingredients  make  up  2  per  cent  of  the  plants.  Ferns,  with 
the  same  amount  of  ash,  afford,  as  the  average,  27  per  cent  of  silica,  with  no  alumina. 
Equiseta  afford,  on  an  average,  20  per  cent  of  ash,  and  50  per  cent  of  this  may  be  silica. 


664  HISTORICAL   GEOLOGY. 

Supposing,  now,  that  Lycopods  (Lepidodendrids,  etc.)  afforded  one  half  the  material 
of  the  coal-beds,  and  the  other  plants  the  rest,  and  that  the  silica  and  alumina  of  the 
former  averaged  40  per  cent,  and  of  the  latter  only  27  per  cent,  this  being  all  silica,  then 
the  amount  of  these  ingredients  afforded  by  the  vegetation  would  be  1  -66  per  cent  of  the 
whole  weight  when  dried.  This  would  make  the  amount  of  silica  and  alumina,  in  the 
bituminous  coal  made  from  such  plants  (supposing  three  fifths  of  the  material  of  the  wood 
lost  in  making  the  coal,  as  estimated  on  page  713),  4  per  cent ;  and  the  whole  amount  of 
ash  about  4-75  per  cent.  At  the  same  time,  the  ratio  of  silica  to  alumina  would  be  nearly 
3  to  2, 

Now  many  analyses  of  bituminous  coal  have  obtained  not  over  3  per  cent  of  ash,  or 
impurity,  although  the  general  average,  excluding  obviously  impure  kinds,  reaches  4-5  to 
6  per  cent ;  being,  for  the  coals  of  the  northern  half  of  Ohio,  5-12,  and  for  the  southern 
half,  4-72. 

It  hence  follows  that  (1)  the  whole  of  the  impurity  in  the  best  coals  may  have  been 
derived  from  the  plants  ;  (2)  the  amount  of  ash  in  the  plants  was  less  than  the  average  in 
modern  species  of  the  same  tribes  ;  (3)  the  winds  and  waters  for  long  periods  contributed 
almost  no  dust  or  detritus  to  the  marshes ;  and  (4)  the  ash,  or  else  the  detritus,  was 
greatest  in  amount  toward  the  borders  of  each  marsh-region.  In  that  era  of  moist  climate 
and  universal  forests,  there  was  almost  no  chance  for  the  winds  to  gather  dust  or  sand  for 
transportation. 

In  rare  cases,  an  occasional  bowlder  or  rounded  stone  has  been  found  in 
a  coal-bed,  as  well  as  in  other  layers  of  the  Coal-measures.  E.  B.  Andrews 
describes  one  of  quartzyte,  lying  half  buried  in  the  top  of  the  Nelsonville 
coal-bed,  at  Zaleski,  Ohio,  which  was  12  and  17  inches  in  its  two  diameters. 
F.  H.  Bradley  reports  one,  also  of  quartzyte,  about  four  by  six  inches,  found 
in  the  middle  of  the  coal-bed  mined  at  Coal  Creek,  E:ist  Tennessee.  These 
may  have  been  dropped  from  the  roots  of  floating  trees,  as  has  happened  to 
masses  of  basaltic  rocks  occasionally  found  upon  the  coral  atolls  of  the  Pacific. 

Sulphur  also  occurs,  in  some  coal-beds,  as  a  constituent  of  a  resinous  sub- 
stance ;  and  Wormley  suggested  that  part  of  the  sulphur  in  the  Ohio  coals 
is  in  some  analogous  state. 

The  mineral  oil  and  gas  of  western  Pennsylvania  come  wholly,  or  nearly 
so,  from  Chemung  beds  of  the  Devonian  —  not  from  the  Carboniferous  (page 
606). 

2.  Iron  Ores.  — The  ore-bearing  layers  of  the  Subcarboniferous  and  Carbon- 
iferous series  occur  in  connection  usually  with  the  beds  either  of  limestone  or 
of  shale,  but  sometimes  with  the  sandstone  and  coal-beds.  As  these  ores  are 
more  or  less  impure  from  mixture  with  clay,  they  are  called  day-ironstone.  The 
limestones  often  contain  iron  carbonate  (siderite) — a  gray  ore,  stone-like  in 
aspect,  of  specific  gravity  3-7  to  3-8.  It  occurs  either  in  solid  beds,  from  a 
few  inches  to  two  or  three  feet  in  thickness,  or  in  nodules,  or  "  ball  ore," 
more  or  less  united  into  a  layer.  The  same  limestone  often  contains  also 
nodules  of  another  valuable  ore,  limonite  (page  71),  the  ore  which  affords  a 
brownish  yellow  powder,  though  often  brownish  black  to  black  in  outside 
color.  This  limonite  has  frequently  been  made  by  the  oxidation  of  the 
siderite.  The  Ferriferous  limestone,  just  below  the  Kittanning  coal-bed,  con- 
tains both  of  the  ores  mentioned.  The  limonite  in  nodules,  or  as  a  "  ball 


PALEOZOIC   TIME  —  CARBONIC.  665 

ore,"  is  common  also  in  beds  of  shale,  in  layers  of  a  few  inches  to  a  foot  or 
more  in  thickness,  and  sometimes  forms  beds  beneath  the  fire  clay  that 
underlies  a  coal-bed.  Another  kind  of  clay-ironstone  is  hematite  or  iron- 
sesquioxide,  looking  usually  as  stone-like  as  the  preceding,  but  distinguished 
by  its  affording  a  red  powder.  These  ore-masses  are  often  siliceous,  from 
disseminated  silica,  and  therefore  very  hard. 

These  ores,  but  especially  the  first  two,  are  a  very  important  source  of 
iron  in  coal  regions.  The  nodules  are  of  concretionary  origin ;  that  is,  were 
made  by  the  concreting  together  of  iron  oxide  from  iron-bearing  salts  carried 
down  into  marshes,  and  are  not  transported  stones  rounded  by  friction. 

3.  Clay-beds.  —  Abed  of  fire  clay  has  been  mentioned  as  usually  underlying 
a  coal-bed.     The  clay  varies  in  purity  on  one  side  down  to  sandy  clay,  or  to 
carbonaceous  shales,  and  on  the  other  to  the  purest  of  white  clays,  valuable 
for  making  pottery,  fire-brick,  and  tile  (see  page  81).     The  thickness  of  the 
beds  varies  from  a  few  inches  to  sometimes  half  a  dozen  feet.     They  are  apt 
to  be  more  or  less  discolored  by  iron-oxide,  so  as  to  make  cream-colored 
instead  of  white  pottery ;  and  sometimes  the  bed  overlies  a  bed  of  iron  ore, 
.-and  is  pure  white  only  at  top. 

The  very  common  presence  of  pure  white  clays  in  the  Coal-measures  is  a 
•consequence  of  the  production  of  carbonic  acid,  and  also  of  organic  acids,  by 
:the  vegetable  decomposition  that  goes  on  indefinitely  in  the  plant  beds.  The 
sediments,  whether  of  sand  or  mud,  contain  more  or  less  feldspar;  and  the 
action  of  these  acids  on  the  feldspar  removes  the  alkali  and  produces  the 
•clay  (page  129) .  The  clay  so  made  will  be  at  first  colored  by  iron  oxide,  if 
.any  iron-bearing  mineral  is  present  (the  common  fact);  but  the  vegetable 
decomposition  going  forward  results  in  partly  deoxidizing  the  iron  oxide 
(reducing  it  to  FeO);  and  then  the  iron  in  this  state  is  taken  up  by  the  acids 
and  carried  off  in  solution  (page  124)  until  the  blanching  in  many  cases  is 
complete  through  part  or  all  of  a  thick  bed.  The  abundance  of  carbonic  acid, 
set  free  under  the  conditions  described,  accounts  also  for  the  very  frequent 
occurrence  of  iron-carbonate  (or  siderite)  mentioned  above. 

The  presence  of  potash  or  soda  in  the  clay  is  probable  evidence  of  the 
presence  of  undecomposed  feldspar,  and  of  over  7  per  cent  of  it  to  1  per  cent 
of  the  alkali  —  a  point  of  geological  as  well  as  economical  interest;  for  such 
clays  are  fusible  and  not  properly  fire  clays,  and  therefore  are  not  suitable  for 
fire  brick.  The  presence  also  of  lime  and  iron  gives  the  clays  fusibility.  On 
Ohio  clays,  see  Ohio  G.  Rep.,  v.,  656. 

4.  Salt.  —  Saline  waters  have  been  obtained  in  many  regions  from  borings 
down  to  the  Carboniferous  strata,  but  usually  they  are  only  saline  enough  to 
be  spoilt  water.     In  Michigan,  strong  brines  are  supplied  from  the  Sub- 
carboniferous  beds,  and  they  are  used  for  the  manufacture  of  salt  in  the 
Saginaw   valley.     The   same   beds   contain   extensive  deposits  of  gypsum. 
In  Ohio,  productive  brines  come  partly  from  the  same  horizon.     Those  of 
Kanawha  in  West  Virginia  are  from  the  lower  part  of  the  Coal-measures; 
and  Kansas  beds  of  the  same  period  have  been  found  to  afford  brines. 


666 


HISTORICAL    GEOLOGY. 


LIFE  OF   THE   CARBONIFEROUS   PERIOD. 


PLANTS.  — Forests  and  jungles  made  of  Cryptogams  of  the  tribes  of  Fernsv 
Equiseta,  and  Lycopods,  along  with  Gymnosperms  related  to  the  Cycads  and 
Yews,  and  covering  interminable  marshy  plains  and  fields,  were  the  striking 


1031. 


Carboniferous  vegetation.     Russell  Smith. 

feature  of  the  coal  era.  Though  desolated  again  and  again,  either  universally 
or  partially,  by  the  returning  waters,  and  over  the  large  submerged  areas  kept 
desolate  for  many  centuries  or  series  of  centuries  again  and  again,  the  ver- 
dure in  all  its  luxuriance  spread  over  the  emerging  land,  with  little  change 
in  the  foliage,  for  other  times  of  luxuriant  growth  and  of  peat-making.  Only 
toward  the  close  of  the  era,  when  the  Permian  period  was  commencing,  had 
the  forests  lost  the  larger  part  of  their  great  trees  of  the  tribe  of  Lycopods. 

Unlike  the  present  world,  there  were  no  Angiosperms  and  no  Palms.  It 
is  not  positively  known  that  there  were  Endogens  of  any  kind.  There  was 
certainly  no  grass  over  the  fields,  the  most  common  of  Endogens.  With 
Angiosperms  and  Endogens  absent,  there  were  no  conspicuous  flowers,  no 
beautiful  foliage  except  that  of  the  Ferns  and  fern-like  trees,  and  no  fruit 


PALEOZOIC    TIME CARBONIC. 


667 


and  no  fragrance  but  that  of  Conifers  and  Cycads.  Even  Mosses,  so  common 
in  modern  swamps,  and  the  chief  source  of  modern  peat,  have  left  no  evi- 
dence of  their  presence. 

A  general  idea  of  the  vegetation  and  scenery  of  the  era  during  its  periods 
of  verdure  may  be  gathered  from  the  accompanying  ideal  sketch  (Fig.  1031), 
from  a  painting1  by  Russell  Smith.  The  tree  to  the  left  of  the  center, 
and  others  with  similar  palm-like  tops,  are  the  Tree-ferns ;  and  smaller  Ferns 
make  up  much  of  the  foreground.  The  other  trees  are  Lycopods,  the  Lepi- 
dodendrids ;  and  one  bare 

trunk  to  the  right  is  that  of  1032' 

a  Sigillaria.  Other  straight 
stems  with  leaves  (or  branch- 
lets)  at  regular  intervals  are 
the  Equiseta  or  Calamites. 
The  Cycad-like  Cordaites, 
with  their  long  strap-like 
leaves,  with  probably  others 
having  almost  the  foliage  of 
a  Fern-tree,  should  have  been 
in  the  view ;  for  they  added 
largely,  as  Lesquereux  and 
others  have  stated,  to  the 
forest  trees.  But  of  other 
Grymnosperms,  the  so-called 
Conifers,  there  are  few  indi- 
cations in  the  beds.  They 
may  have  been  common  over 
the  drier  fields  and  hills. 

Forests  made  of  the  Equi- 
seta and  Lycopods  of  to-day 
would  hardly  overtop  a  man's 
head.  TheyVould  be  simply 
shrubbery  of  "Horse-tails" 
and  "Ground  Pines."  The 
height  of  the  largest  modern  Lycopod  is  five  to  six  feet ;  that  of  the  ancient, 
60  to  90  feet.  In  habit  and  in  foliage  they  were  much  like  the  Spruces  and 
Pines  of  the  present  day,  the  length  of  the  leaves  varying  greatly,  as  illus- 
trated in  Fig.  1032.  The  Equiseta  of  the  present  time  are  slender, 
herbaceous  plants,  with  hollow  stems  ;  while  the  Calamites  of  the  Carbonifer- 
ous marshes  included  species  having  partly  woody  trunks,  a  diameter  of  3  to 
10  inches,  and  a  height  of  30  or  40  feet.  Ferns  now  grow  into  trees  in  tropi- 
cal and  warm  temperate  climates,  but  only  small  trees,  and  poor  in  wood 
compared  with  some  in  the  coal  era. 

While  the  terrestrial  vegetation  was  thus  abundant,  seaweeds  after  the 
old  style  were  still  in  the  waters.     The  Spirophyton  caudagalli  of  the  Lower 


Extremity  of  a  branch  of  Lepidodendron,  with  the  leaves  attached. 


668 


HISTORICAL   GEOLOGY. 


Devonian,  or  a  related  species,  is  common  in  some  portions  of  the  Pottsville 
conglomerate  in  Kentucky  and  elsewhere. 

1.  Vascular  Cryptogams.  —  Lycopods.     The  Lepidodendron  trees  had  the 
exterior   embossed  with  oblong  scars,  as  in  Figs.  1033,   1034,  and  1036. 


1033. 


1035. 


Fig.  1033,  Lepidodendron  aculeatum ;  1034,  Lepidodendron  clypeatum ;  1035,  Halonia  pulchella.    Fig.  1033,  Fair- 
child  ;  1034,  1035,  Lesquereux. 

Leaves  like  those  of  the  Spruce  or  Pine  occasionally  occur  on  the  fossil  stems 
(Fig.  1040);  and  in  some  foreign  specimens  of  L.  Sternbergii  Brgt.,  from  Aus- 
trian coal-beds,  they  are  over  a  foot  long,  and  as  closely  crowded  on  the 
branches  as  in  any  modern  pine.  The  Lycopodium  dendroideum  of  modern 
forests,  if  magnified  largely,  would  give  a  good  idea  of  the  aspect  of  the 


1036. 


1036-1038. 
1037. 


o 


Fig.  1036,  Lepidodendron  Veltheimanum  ;  103T,  Sigillaria  SiUimani ;  1038,  S.  Pittstonana.     Lesquereux. 

trees.  The  cones  of  Lepidodendrids  were  long,  and  much  like  those  of  a 
living  Lycopod,  and  are  referred  to  under  the  name  Lepidostrobus,  and  the 
leaves  of  the  cone  under  that  of  Lepidophyllum.  The  stems,  called  Lycopo 


PALEOZOIC    TIME  —  C A KBONIC. 


669 


dites,  are  slender,  small-leaved,  and  much  like  those  of  Lycopodium  dendroi- 
deum,  though  often  large.  The  Halonia,  Fig.  1035,  is  a  decorticated  stem  or 
rootlet  of  uncertain  relations.  Two  species  of  Sigillaria  are  represented  in 
Figs.  1037,  1038.  The  figures  show  that  the  scars  are  peculiar  in  having  at 
the  center  a  dot,  and  a  short  convex  line  either  side ;  the  exterior  of  the  stem 
is  generally  vertically  banded  or  costate,  as  in  the  figures. 


1039-1044. 


1039. 


1040. 


1042. 


1044. 


1041. 


LYCOPODS.  —  Fig.  1039,  Lepidostrobus  hastatus  (or  cone  of  a  Lepidodendron) ;  1040,  Lepidodendron  lanceola- 
tum,  Lx. ;  1041,  Stigmaria.  SCARS  OF  TREE-FERNS.  —  Fig.  1042,  Stemmatopteris  punctata  (x£) ;  1043,  Mega- 
phyton  McLayi  ;  1044,  Cyathea  compta.  Figs.  1039-1043,  Lesquereux ;  except  1041,  Dawson. 

In  both  Sigillarids  and  Lepidodendrids,  the  appearance  of  the  scars  of 
the  same  species  varied  much  with  age ;  moreover,  the  same  scar  is  wholly 
different  in  form  at  the  surface  from  what  it  is  below,  as  Figs.  1037,  1038 
illustrate.  The  trunk,  while  woody  and  firm  outside,  consisted  inside  mostly 
of  cellular  tissue,  with  usually  a  very  large  pith  along  the  center ;  and  hence 
the  stumps  easily  became  hollow  by  decay.  Such  hollow  stumps,  filled  with 
sand  or  clay,  are  common  in  the  Coal-measures ;  and  sometimes  there  remain 
only  casts  of  them  in  sand  having  a  scarred  exterior. 


670 


HISTORICAL  GEOLOGY. 


One  of  the  cones  of  a  Lepidodendrid  from  Pittsburg,  Pa.,  is  represented 
in  Fig.  1039. 

The  Stigmarice,  which  were  either  roots  or  under-water-stems  of 
Sigillarids  or  Lepidodendrids,  were  often  large,  many  of  the  fossil  stems 
being  four  to  six  inches  in  diameter.  Fig.  1041  represents  a  portion  of  a 
stem,  with  its  rounded  impressions  or  scars.  When  perfect,  each  scar  was 
the  base  of  a  long  and  slender  leaf-like  appendage. 

1045-1048. 


1046 


TERNS.  —  Fig.  1046,  Odontopteris  Schlotheimi ;  1046,  Alethopteris  lonchitica ;  1047,  Sphenopteris  (Hymeno- 
phyllites)  Hildrethi ;  1047  a,  portion  of  the  same,  enlarged  ;  1048,  Sphenopteris  Gravenhorstii ;  1048  a,  portion 
of  the  same,  enlarged.  Figs.  1045-1047,  Lesquereux  ;  1048,  Brongniart. 

Ferns.  —  Two  of  the  large  scars  of  stems  of  Tree-ferns  are  shown  in 
Figs.  1042, 1043 ;  and,  for  comparison,  one  from  a  modern  Tree-fern  (resembling 
the  tree  to  the  left  in  the  sketch,  page  666)  is  represented  half-size  in 
Fig.  1044.  The  trunks  of  Tree-ferns  consist  within  of  vertically  plicated 
woody  plates,  with  more  or  less  cellular  tissue  between,  and  not  of  concentric 
rings.  The  twisted  plates  are  sometimes  well  shown  in  a  transverse  section 
of  a  fossil  trunk  from  the  Coal-measures. 

The  variety  of  Ferns  was  very  large.     Some  of  the  more  common  forms 


PALEOZOIC   TIME  —  CARBONIC. 


671 


are  represented  in  Figs.  1045  to  1052.  The  genus  Neuropteris  (Figs.  1049, 
1050)  is  one  of  the  most  abundant  in  species.  The  basal  leaves  (Figs.  1050, 
1052)  vary  widely  in  form  in  the  same  species,  and  are  sometimes  delicately 
fimbriated.  Odontopteris  (Fig.  1045)  has  many  species  ;  and  so  also  Alethop- 
teris  (Fig.  1046),  Sphenopteris  (Figs.  1047,  1048),  and  Pecopteris  (Fig.  1051). 


1049-1056. 


1053 


FERNS. —Figs.  1049,  1049  a,  Neuropteris  Loschii,  parts  of  the  same  leaflet;  1050,  Neuropteris  hirsute ;  1051, 
Pecopteris  arborescens ;  1051  a,  a  portion  of  the  same,  enlarged  ;  1052,  basal  leaf  of  Neuropteris  tenuifolia. 
EQUISETA.— 1053,  Asterophyllites  equisetiformis ;  1053  a,  the  same  (?)  with  sporangia  at  the  axils  of  the 
leaves ;  1054,  A.  sublaevis ;  1055,  Calamites  cannaeformis  ;  1055  a,  surface-markings  of  same,  enlarged.  —  Fig. 
1056,  Sphenophyllum  Schlotheimi.  Figs.  1049-1054,  1056,  Lesquereux  ;  1055,  Brongniart. 

Equiseta.  —  The  more  common  Equiseta  of  the  Coal-measures  are 
species  of  Calamites,  as  in  the  Devonian.  One  of  the  jointed,  delicately 
fluted  stems  is  represented  in  Fig.  1055 ;  and  the  junction  of  the  flutings  of 
the  surface  at  a  joint,  in  Fig.  1055  a.  The  Asterophyllites  (Fig.  1053)  and  An- 
nularice  are  sometimes  branches  of  the  same  plant,  the  former  occurring  toward 
its  base.  Fig.  1053  a  shows  the  sporangia  at  the  base  of  the  leaves. 

Fig.  1056  represents  a  common  species  of  Sphenophyllum ;  the  name 
alludes  to  the  wedge-shaped  leaves ;  W.  C.  Williamson  states  (1894)  that  the 


672 


HISTORICAL  GEOLOGY. 


species  are  not  related  in  fructification  to  the  Lycopods  or  Equiseta,  or  to 
any  known  group  of  Cryptogams. 

2.  Gymnosperms  of  the  Order  of  Cycads.  —  The  character  and  fruit  of 
Cordaites  has  been  well  illustrated  by  Lesquereux  from  specimens  obtained 
at  Cannelton,  Pa.  Fig.  1057  shows  the  Cycad-like  foliage ;  and  Fig.  1057  a 

1057. 


Fig.  1057,  Cordaites  costatus  ;  1057  a,  fruit,  with  a  portion  of  the  attached  stem.     Lesquereux. 

represents  fruit  which  occurs  at  the  same  locality,  and  is  found  there  so* 
closely  associated  with  the  leaves  as  to  be  probably  of  the  same  species. 
Lesquereux  figures  the  leaves  and  fruit  also  of  C.  Mansfieldi  from  this 
locality,  a  species  with  much  broader  leaves,  and  nuts  of  a  smooth 
obovate  form,  2^-  inches  long. 

The  Sigillarids  are  referred  to  this  division  of  the  Gymnosperms  by  Re- 
nalt  and  Dawson,  but  to  the  Lycopod  tribe  by  Williamson  and  most  authors.. 


PALEOZOIC   TIME  —  CARBONIC.  673 

The  fruit  of  Cordaites  (Cordaicarpus)  Gutbieri  is  represented  in  Fig.  1062. 


1058o 


1058  c 


1060 


1062-1068. 


1066 


FBtnrs.  —  Figs.  1058  a,  6,  c,  Trigonocarpus  tricuspidatus  ;  a,  the  exterior  husk  or  rind ;  6,  the  nut  separate  from 

the  rind  ;  c,  kernel ;  1059,  nut  of  Trigonocarpus  ?  ;  1060,  T.  ornatus  ;  1060  a,  vertical  view  of  summit, 

showing  the  ribs  of  the  surface ;  1061,  Cardiocarpus  bicuspidatus.    Newberry. 

The  Cordaites  had  a  large  pith,  like  that  named  Artisia  and  Sternbergia,  as 
figured  by  Lesquereux  on  plate  Ixxxi.  of  his  Pennsylvania  Report.  The  gen- 
era Lepidoxylon,  Dicrano- 
phyllum,  Tcemophyllum 
are  related  to  Cordaites, 
and  probably  others  in 
which  the  pith  is  large. 

3.  Gymnosperms  re- 
lated to  the  Yews.  —The 
other  Gymnosperms  of 
the  era,  usually  called 
Conifers,  were  probably 
related  to  the  Taxineae 
or  Yews,  which  have 
single  fruit  instead  of 
cones,  and  vary  widely 
in  foliage,  the  leaves 
sometimes  broad,  and 
occasionally  Fern-like. 
From  such  trees  came 
probably  the  fossil  nuts, 
as  suggested  by  Hooker. 
The  above  figures  are 
from  Newberry's  Ohio 
Keport.  Fig.  1058  rep- 
resents one  of  the  three- 
sided  or  six-sided  fruits, 

called  Trigonocarpus:  1058  a,  the  husk;  6,  the  nut;  c,  the  kernel. 
DANA'S  MANUAL  —  43 


FRUITS.  —  Fig.  1062,  Cordaicarpus  Gutbieri ;  1063,  Cardiocarpus  elonga- 
tus ;  1064,  C.  samaraefonnis ;  1065,  C.  bisectus ;  1066,  Botryoconus 
(Antholithes)  Pitcairniae  ? ;  1067,  B.  priscus ;  1068,  Cordaianthus,  flow- 
er (fruit  ?)  of  a  Cordaites.  Fig.  1062,  Lesquereux ;  1063,  1064,  1066- 
1068,  Newberry  ;  1065,  Dawson. 


Fig.  1059 


674  HISTORICAL  GEOLOGY. 

is  the  nut  of  another  species.  Figs.  1063  to  1065  represent  species  of  Car- 
diocarpus;  they  resemble  the  fruit  of  the  anomalous  Gymnosperms  of 
Africa,  Welwitschia  (page  435).  The  peculiar  but  beautiful  fan-shaped 
leaves,  named  Wliittleseya  elegans  by  Newberry,  are  of  unascertained  relations. 
Figs.  1066, 1067  are  supposed  to  be  fruit  of  Gymnosperms,  in  different  stages 
of  development ;  and  Fig.  1068,  fruit  of  doubtful  species. 

Figs.  1066,  1067  have  the  forms  of  half  developed  flowers  or  leaf-buds, 
and  were  called  Antholithes  by  Newberry.  They  are  referred  to  the  Conifers 
by  Grand'  Eury.  Lesquereux  regards  Botryoconus  prisons  (Fig.  1067)  as  a 
more  advanced  stage  of  B.  Pitcairnice.  Fig.  1068,  Antholithes  of  Newberry, 
is  the  fruit  or  flower  of  a  Cordaites,  according  to  Lesquereux. 

ANIMALS.  —  The  animal  life  of  the  Carboniferous  period  included,  besides 
marine  Invertebrates,  terrestrial  Mollusks,  and  a  large  variety  of  terrestrial 
Articulates,  as  Insects,  Spiders,  Myriapods ;  and,  among  Vertebrates,  besides 
Fishes  and  Amphibians,  a  higher  range  of  life,  in  true  Reptiles.  No  evidence 
has  been  obtained  of  the  existence  then  of  Birds  or  Mammals. 

1.   Rhizopods.  —  Shells  of  Rhizopods,  of  the  shape  and  size  of  a  kernel  of 
wheat,  belonging  to  the  genus  Fusulina,  Figs.  1069,  a,  are  common  in  some 
of  the  shales  and  limestones  of  the  Mississippi  valley  and  beyond, 
in  Illinois,  Kansas,  Utah,  New  Mexico,  California,  and  elsewhere. 


In  British  Columbia,  on  Fraser's  River,  at  Marble  Canon,  the 
Fusulince,  of  a  thick  limestone,  are  associated  with  a  very  abun- 
dant arenaceous  Rhizopod,  T37  of  an  inch  long,  shaped  like  an 
elongated  shot,  which  has  been  referred  to  the  genus  Loftusia, 
and  named  L.  Columbiana.  In  Europe  the  Fusulinse  are  found 
in  Subcarboniferous  beds  as  well  as  in  the  Carboniferous  and 
Lower  Permian. 

2.  Actinozoans  and  Echinoderms.  —  Corals,  seldom  abundant,  are  of  the 
genera  Lophophyllum,  Zaphrentis,  Lithostrotion,  and  others.     Lophopliyllum 
proliferum  McChesney  occurs  in  roof  shales  over  coal  at  Springfield,  111. 
Crinoids  are  few  compared  with  those  of  the  Subcarboniferous  ;  Illinois  has 
afforded  about  a  dozen  species ;  and  Missouri  others.      In  Nevada,  Arizona, 
New  Mexico,  Nebraska,  etc.,  have  been  found  a  few  Echinoids  of  the  genus 
Archceocidaris. 

3.  Molluscoids  and  Mollusks.  —  The  Brachiopods  are  similar  in  genera  to 
those  of  the  Subcarboniferous,  though  partly  of  new  species ;  and  the  same 
is  true  in  the  main  of  the  marine  Gastropods,  Lamellibranchs,  and  Cephalo- 
pods.     Some  of  the  characteristic  species  are  here  figured :  a  characteristic 
Productus  in  Fig.  1070,  a  Chonetes  in  1071,  and  Gastropods  in  1076  to  1080. 

But  besides  marine  Gastropods,  the  Coal-measures  have  afforded  the 
first  known  of  terrestrial  shells.  One  of  the  small  land-snails,  or  Pulmonates, 
is  represented,  a  little  enlarged,  in  Fig.  1081,  —  a  species  found  in  the  Nova 
Scotia  Coal-measures,  and  described  by  Dawson ;  and  Figs.  1082,  1083,  from 
F.  H.  Bradley,  show  the  forms  of  two  others  from  Illinois. 


PALEOZOIC   TIME  —  CARBONIC. 


675 


Among  the  Cephalopods,  the  Nautiloids,  as  Hyatt  observes,  reach  their 
greatest  expansion  in  the  Carboniferous  period.     They  include  species  of 


1070-1073. 


BBAOHIOPODS.  —  Fig.  1070,  Productus  Nebrascensis ;  1071,  Chonetes  mesolobus  ;  1072,  Spirifer  cameratus ;  1078, 
Seminula  (Athyris)  subtilita.     Fig.  1070,  Hall ;  1071-1073,  Meek. 


1074 


1074-1075. 


1075 


LAMELLIBRANCHS.  —  Fig.  1074,  Macrodon  carbonarius  ;  1075,  Allorisma  subcuneata.     Fig.  1074,  Cox  ;  1075,  Meek. 


1076 


1076-1080. 
1078 


GASTROPODS.  —  Fig.  1076,  Pleurotomaria  tabulata ;  1077,  Bellerophon  carbonarius ;  1078,  Pleurotoinaria  sphfieru- 
lata ;  1079,  Macrocheilus  (?)  fusiformis ;  1080,  Dentaliutn  subheve.  Figs.  1076, 1077,  de  Koninck  ;  1078-1080, 
Hall. 

Orthoceras,  Cydoceras,  Phacoceras  (P.  Dumbli  Hyatt  —  Figs.  1084,  a,  reduced 
one  half),  Temnochilus  (T.  crassum  Hyatt,  Fig.  1085),  and  a  number  of  genera 
with  longitudinal  ridges  and  keels,  as  in  the  Trigonoceratidae.  There  are 
also  species  of  the  Goniatites  group. 

4.  Worms.  —  Sea-worms  or  Annelids  have  been  supposed  to  be  represented 
by  a  small  coiled  shell,  referred  to  the  genus  Spirorbis,  found  attached  to 


676 


HISTORICAL   GEOLOGY. 


the  leaves  and  stems  of  submerged  plants.  The  specimen  figured  is  from 
Nova  Scotia  (Dawson).  They  are  reported  also  from  the  Pennsylvania 
Coal-measures. 


1081. 


1082. 


1081-1085. 
1084  a. 


1084. 


PULMONATE  GASTROPODS.  —  Fig.  1081,  Pupa  vetusta  (x  |) ;  1082,  P.  Vermilionensis  ;  1083,  Dawsonella  Meeki. 
NAUTILOID  CEPHALOPODS.  —Figs.  1084,  a,  Phacoceras  Dumbli  (x  i);  1085,  Temnochilus  crassum.  Fig.  1081, 
Dawson ;  1082,  1083,  F.  H.  Bradley ;  1084,  1085,  Hyatt,  '90. 


1086. 


5.  Limuloids.  — Species  of  the  group  of  Eurypterids  were  common.     Speci- 
mens of  one  of  them,  four  to  ten  inches  long,  the  Eurypterus  Mansfieldi  of 

C.  E.  Hall,  are  found  in  the  shale  below  the  Darlington  cannel 
coal,  near  Cannelton,  Pa.,  laid  out  among  Ferns  and  Calamites, 
as  represented  in  Fig.  1087.  The  species  probably  lived  in  fresh- 
water marshes  and  ponds.  In  addition,  the  modern  tribe  of 
Limulids  had  its  species :  one  from  Morris,  111.,  is  represented  in 
Fig.  1088.  Another  species,  Cyclus  Americanus  of  Packard,  had 
an  even,  nearly  circular  outline,  without  a  telson,  and  closely 
resembled  an  embryonic  Limulus. 

6.  Crustaceans.  —  Trilobites  were  rare,  and  of  the  genera  Phillipsia,  Grif- 
fithides  and  Brachymetopus. 

Under  Crustaceans  there  were  also  various  species  of  modern  aspect, 
represented  in  Figs.  1089  to  1091,  the  latter  two,  if  not  all  three,  true 
Decapods.  The  Myriapods  were  mostly  related  to  the  inferior  lulus  tribe 
—  nearly  cylindrical  species  (as  Figs.  1092,  1093)  having  often  two  pairs 
of  legs  to  a  body  segment.  But  in  one  species,  the  Palceocampa  anthrax  of 
Meek  and  Worthen,  from  Illinois,  the  body  had  but  10  segments ;  and  on  its 


Spirorbis 
carbonarius. 


PALEOZOIC   TIME  —  CARBONIC. 


677 


back  were  tufts  of  minute  spines,  so  that  it  looked  much  like  some  cater- 
pillars. 

7.  Arachnids.  —  Among  Arachnids,  there  were  Spiders  (Fig.  1095)  as  well 
as  Scorpions  (Fig.  1094). 

1088. 
1087. 


Fig.  1087,  Eurypterus  Mansfieldi.    C.  E.  Hall,  '77. 


Fig.  1088,  Prestwichia  Danse.    Meek  and 
Worthen. 

All  the  species  represented  in 
Figs.  1089-1093  are  from  the 
Coal-measures  at  Mazon  Creek, 
in  Morris,  111.,  where  they  occur 
in  the  centers  of  concretions,  and 
were  the  nuclei  about  which  the 
concretions  were  formed.  Thus 
entombed,  they  were  safe  against 
removal  by  infiltrating  waters. 
The  locality  has  afforded  16 
species  of  Myriapods  and  nearly 
a  dozen  kinds  of  Spiders,  besides  Scorpions. 

8.  Insects. — Insects  are  found  at  Morris,  under  the  same  conditions 
(besides  Ferns  and  other  plants),  and  in  the  shales  of  the  Coal-measures 
elsewhere.  The  Neuropter-like,  or  Neuropteroid,  species  are  common  (Figs. 
1096,  1097),  and  still  more  so  the  Orthopteroid,  and  especially  those  of 
Orthopteroids  related  to  the  Cockroach,  a  wing  of  one  of  which  is  shown  in 
Fig.  1098  j  and  less  abundantly  the  species  related  to  the  modern  Phasma 
and  Locust,  the  Protophasmids  (Fig.  1099).  Scudder  enumerates  in  a  recent 
paper  133  American  species  of  Coal-measure  Cockroaches  from  the  Coal- 
measures  of  the  Continent,  pertaining  to  14  different  genera,  and  nearly  all 
are  of  his  own  describing.  Of  these,  56  species  are  from  the  Waynesburg 
coal-bed  at  Cassville,  W.Va.,  where  the  beds  are  Permian,  according  to 
I.  C.  White  ;  12  from  Providence,  R.I. ;  22  from  the  Lower  Barren  Coal- 


678 


HISTORICAL   GEOLOGY. 


measures  at  Richmond,  O. ;  7  from  Pittston,  Pa.,  and  as  many  from  Cannel- 
ton;  17  from  Illinois,  5  from  Missouri,  1  from  Arkansas,  1  from  Kansas,  1  from 
Nova  Scotia,  and  3  from  Cape  Breton ;  and  only  in  one  case  has  a  species 


1089. 


CRUSTACEANS.  —  Fig.  1089,  Acanthotelson  Stimpsoni;  1090,  Palseocaris  typus  (x3) ;  1091,  Anthracopalsemon 
gracilis.  MYRIAPODS.  — 1092,  Xylobius  sigillarise ;  1093,  Euphoberia  armigera.  Figs.  1089-1091,  1098, 
Meek  and  Worthen  ;  1092,  Dawson. 


1095  a. 


1094-1095. 


ARACHNIDS. —Fig.  1094,  Eoscorpius  carbonarius  ;  a,  one  of  the  combs;  1095,  Arthrolycosa  antiqua;  a,  profile, 
showing  the  elevation  of  the  cephalothorax  and  the  position  of  the  legs.  Fig.  1094,  Meek  and  Worthen,  '68 ; 
1095,  Beecher. 


PALEOZOIC    TIME CARBONIC. 


679 


been  found  at  two  localities.  All  of  the  great  marshes  of  the  Continent 
appear  to  have  been  infested  by  Cockroaches.  Probably  the  JSfeuropteroids 
were  equally  numerous,  although  less  common  as  fossils.  The  Insect  fauna 


1096-1099. 
1098. 


1097. 


1099. 


NETTEOPTEKOID  INSECTS.  —  Fig.  1096,  Miamia  Bronsoni ;  1097,  Gerarus  Danse.  ORTHOPTEROIDS.  —  Fig.  1098, 
Etoblattina  venusta,  anterior  wing;  1099,  Paolia  vetusta  (xf).  Fig.  1096,  D.;  1097,  Scudder,  '68;  1098, 
Lesquereux ;  1099,  S.  I.  Smith. 

was  also  remarkable  for  the  large  size  of  many  species.  A  Protophasmid 
of  the  genus  Haplophlebium  of  Scudder,  from  Cape  Breton,  related  to  the 
Locust,  had  an  expanse  of  wing  of  seven  inches.  In  a  Neuropteroid  of  the 
genus  Megathentomum,  from  Illinois,  the  breadth  of  a  wing  was  two  inches, 
and  the  length  over  three.  No  Beetles  (Coleopters)  had  been  found  in  the 
American  Coal-measures  up  to  1894.  The  absence  of  Butterflies  and  all 
Lepidopters,  and  of  Hymenopters  and  Dipters,  is  considered  certain. 

9.  Vertebrates.  —  Fishes.  The  class  of  Fishes  in  the  Carboniferous  included 
only  Selachians  and  Ganoids  ;  and  the  Ganoids  had  still  the  ancient  feature  of 
vertebrated  tails.  Two  of  these  Ganoids,  one  of  them,  a  Coelacanthus,  having 
the  vertebral  column  extending  along  the  middle  of  the  tail,  the  other,  a 
Eurylepis,  are  illustrated  in  Figs.  1100,  1101  :  they  are  from  a  black,  very 
carbonaceous  shale,  at  Linton,  Ohio,  which  abounds  in  Fishes,  and  has 


680 


HISTORICAL  GEOLOGY. 


afforded  Newberry  nine  species  of  Eurylepis,  three  of  Codacanthus,  and  a 
Palceoniscus,  besides  some  Selachian  remains. 

A  Selachian  tooth  from  Illinois,  related  to  the  Petalodus  from  the  Sub- 
carboniferous,  is   represented  of   reduced  size   in  Fig.  1102.     Fart  of  the 


1100-1104. 


1100. 


1103. 


GANOIDS.  —  Fig.  1100,  Eurylepis  tuberculata  ;  1101,  Coelacanthus  elegans.  SELACHIANS.  —  Fig.  1102,  Petalodus 
destructor ;  1103,  fin-spine  ;  1104  a,  b,  dermal  tubercles  of  Petrodus  occidentalis.  Figs.  1100-1102,  Newberry ; 
1103,  F.  H.  Bradley. 

lower  jaw  of  a  Cestraciont  Shark,  named  by  Newberry  and  Worth  en  after 
Agassiz,  is  represented  of  reduced  size  in  Fig.  1105 ;  the  actual  length 
of  the  specimen  was  nearly  24  inches,  and  the  estimated  length  of  the  Shark 

1105. 


CESTBACIONT  SHARK.  — Agassizodus  variabilis  (.xg).     Newberry  and  Worthen. 

15  to  20  feet.  The  teeth  of  the  species  have  been  found  in  the  Upper  Coal- 
measures  of  Kansas,  Illinois,  and  Iowa.  A  mouth  so  paved  was  a  most 
effective  crushing  organ. 

Fin-spines  of  Sharks  occur  of  many  kinds  and  sizes.  A  portion  of  a 
small  one  is  represented  in  Fig.  1103.  The  bony  tubercles,  Figs.  1104  a,  &, 
were  found  with  the  spine,  and  are  supposed  to  be  from  the  surface  of  the 
body  of  the  same  Fish. 

Large  spines  of  species  of  Edestus,  having  one  edge  armed  with  great 
teeth,  as  in  Figs.  1106,  1107,  have  been  found  in  the  Coal-measures  of 
Indiana,  Illinois,  and  Arkansas.  In  E.  minor  of  Newberry,  Fig.  1107,  the 
teeth  are  nearly  two  inches  long,  and  in  E.  giganteus  Newberry,  Fig.  1106, 


PALEOZOIC   TIME  —  CARBONIC. 


681 


nearly  three  long  and  two  broad.  The  figure  of  the  latter  represents, 
reduced,  only  a  small  portion  of  the  specimen ;  as  figured  by  Newberry  the 
spine  has  five  teeth ;  when  entire  it  was  probably  18  inches  in  length,  and 
occupied,  along  the  body  of  the  Shark,  according  to  Newberry,  the  place  of 
the  posterior  dorsal  fin.  It  could  thus  rip  open  its  prey  when  swimming 
underneath  it,  and  slash  effectually  in  defense. 

Amphibians.  —  Besides  footprints,  which  thus  far  are  the  only  evidence 
of  Amphibians  in  the  Subcarboniferous,  the   Coal-measures  have  afforded 

1106-1107. 


FIN-SPINES  OF  SHARKS.  —  Fig.  1106,  Edestus  giganteus  ;  1107,  E.  minor  (each  x|).     Newberry. 

remains  of  skeletons.  They  show  that  many  of  the  earlier  kinds  were  much 
like  their  predecessors,  the  higher  Ganoid  nnd  Dipnoan  Fishes,  in  having  a 
bony  cranium  instead  of  one  with  large  open  spaces  and  little  bone,  like  the 
modern  Frog ;  and  in  allusion  to  the  ivell-roofed  head,  they  are  called  Stegocephs 
by  Cope.  Among  modern  Amphibians  only  some  snake-like  kinds  have  a 
similar  cranium.  They  are  also  like  the  Fishes  in  their  teeth,  the  most  of 
them  having  the  enamel  inflexed  along  the  surface  grooves,  producing  the 
Labyrinthine  texture  which  suggested  for  the  species  the  name  of  Labyrintho- 
donts.  Further,  they  generally  have  biconcave  vertebrae,  like  Fishes. 
Moreover,  the  Amphibians  occur  of  all  grades  from  (1)  Shake-like  forms 
without  limbs,  to  (2)  those  with  feeble  swimming  organs  ;  and  thence  to 
(3)  the  four-limbed  species  of  various  sizes,  up  to  kinds  as  large  and  formid- 
able as  Alligators.,  It  is  interesting  to  note  also  that  the  feet  have  five  toes 
(or  less),  and  the  fingers  the  modern  number  of  bones. 

The  Coal-measures  of  Ohio,   at   Linton,    afforded  Newberry   numerous 


682  HISTORICAL   GEOLOGY. 

specimens,  and  other  regions  have  added  to  the  number.  Of  the  snake-like 
species,  part  without  limbs,  and  others  with  feeble  limbs,  Cope  has  made  out 
over  a  dozen  species  from  Linton.  Phlegethontia  linearis  of  Cope  had  no  limbs, 
and  the  proportion  of  a  Whip-snake;  and  Molgophis  macrurus  was  nearly 
of  the  size  of  the  common  Rattlesnake.  One  of  these  nearly  snake-like 
species,  Ptyonius  serrula  of  Cope,  is  represented  in  Fig.  1112 ;  it  had  hind- 
limbs,  but  no  fore-limbs.  A  four-limbed,  Salamander-like  species,  Pelion 
Lyelli,  from  Linton,  described  in  1857  by  Wyman,  is  shown  in  Fig.  1109 ;  and 
in  Fig.  1108,  another  species,  the  Amphibamus  grandiceps  of  Cope,  from 
Illinois.  Leptophractus  obsoletus  Cope,  from  Linton,  of  Alligator  size,  had 
stout  teeth  three  fourths  of  an  inch  long. 

Nova  Scotia  has  afforded  species  of  Dendrerpeton  and  Hylerpeton  of  Owen, 
and  of  Hylonomus  of  Dawson,  the  last  peculiar  in  having  a  slender  head. 
The  Nova  Scotia  species  come  mostly  from  the  South  Joggins,  where  they 
were  first  discovered  by  Lyell  and  Dawson  in  1851.  They  were  found  in 
the  sandstone  filling  the  once  hollow  trunks  of  large  Sigillariae,  along  with 
land-shells  (Pupa  vetusta,  Fig.  1081)  and  Myriapods  (Xylobius  sigillarice, 
Fig.  1092);  and  leaves  of  Ferns  and  Cycads,  and  this  mode  of  occurrence 
suggested  the  name  Dendrerpeton  (or  tree-reptile).  The  conditions  appear 
to  show  that  the  hollow  stumps,  the  poor  pithy  wood  of  which  had  decayed 
as  they  stood  in  the  marshes,  were  the  resort  of  the  Amphibians,  and  a 
catch-place  for  other  species  of  the  wet  region ;  or,  that  the  shells  were 
the  food  of  the  Amphibians,  as  Dawson  suggests,  who  states  that  he  has 
found,  in  the  stomach  of  a  recent  Menobranchus  (M.  lateralis  Harlan),  as 
many  as  11  unbroken  shells  of  the  fresh- water  snail,  Physa  heterostropha.  In 
1876,  Dawson  obtained  at  the  Joggins,  from  a  stump  18  inches  in  diameter, 
remains  of  13  Amphibian  skeletons,  pertaining  probably  to  six  species.  The 
Baphetes  planiceps  Owen,  of  Nova  Scotia,  had  a  head  3^  inches  broad. 

The  South  Joggins  has  also  afforded,  about  5000  feet  below  the  top  of 
the  Coal-measures,  two  biconcave  vertebrae  (Fig.  1111,  with  the  cross-section, 
1111  a),  which  are  the  basis  of  the  species  Eosaurus  Acadianus  Marsh.  The 
vertebrae  resemble  those  of  an  Enaliosaur  (Sea-Saurian,  page  785),  but,  as 
observed  by  Huxley,  from  his  observations  on  the  Anthracosaurus  Russelli 
of  the  British  Coal-measures,  and,  as  recognized  by  Marsh,  they  probably 
belonged  to  a  large  Amphibian. 

Footprints  of  Amphibians  occur  in  the  Coal-measures  of  Pennsylvania. 
Indiana,  Illinois,  Kansas,  and  Nova  Scotia.  Figs.  1113  to  1116  represent 
tracks  of  four  out  of  five  species  described  by  Marsh  from  the  middle  of 
the  Coal-measures  in  Osage,  Kan.  All  are  from  one  surface  about  12  feet 
square.  Between  the  right  and  left  tracks  in  Fig.  1113,  there  is  the  im- 
pression of  the  tail.  In  the  tracks  of  Dromopus,  having  long  slender  toes, 
the  phalanges  or  joints  are  very  distinct,  and  on  account  of  the  form,  Marsh 
questions  whether  the  species  may  not  have  been  Reptilian;  but  he  regards 
the  sweep  of  the  foot  in  walking,  indicated  by  the  lines  between  the  two 
tracks  to  the  right,  as  favoring  Amphibian  relations.  So  many  kinds  of 


1108. 


PALEOZOIC   TIME  —  CARBONIC. 
1108-1112. 


683 


AMPHIBIANS.  —  Fig.  1108,  Amphlbamus  grandiceps  (x  2) ;  1109,  Pelion  Lyelli ;  1110,  Molgophis  macrurus?; 
1111,  1111  a,  Eosaurus  Acadianus,  vertebra  (x  J)  ;  1112  a,  6,  c,  d,  Ptyonias  serrula.  Figs.  1108,  1109,  1110, 
J.  Wyman  ;  1111,  Marsh  ;  1112,  Cope. 


684 


HISTORICAL   GEOLOGY. 


tracks  on  so  small  an  area  show  that  the  Amphibians  of  the  period  were  in 
great  numbers. 

1113. 


1114. 


1115. 


1116. 


FOOTPRINTS  OF  AMPHIBIANS.  — Fig.  1113,  Nasopus  caudatus;  1114,  Limnopus  vagus;  1115,  Dromopus  agilis ; 
1116,  Baropus  lentus  (x^).     Marsh,  '94. 


LIFE  OP  THE  PERMIAN  PERIOD. 

PLANTS.  —  The  vegetation  of  the  Upper  Barren  Coal-measures  or  Permian 
strata  of  Pennsylvania  and  West  Virginia  (page  651),  is  characterized,  as 
shown  by  Fontaine  and  White,  by  the  absence  of  Lepidodendrids ;  by  the 
rarity  of  Sigillarice,  only  two  being  known;  by  the  large  number  of  species  of 
Ferns  (over  30)  of  the  genus  Pecopteris,  some  arborescent,  and,  only  a  third 


PALEOZOIC   TIME CARBONIC. 


685 


of  them  known  to  occur  in  the  Coal-measures,  with  other  species  of  the 
related  genera  Cymoglossa,  Goniopteris,  Callipteridium,  Callipteris,  and  also 
of  Neuroptens,  Sphenopteris,  Alethoptens,  Odontoptens ;  many  species  of  the 
Equisetum  tribe,  of  the  genera  Sphenophyllum,  Annularia  and  Equisetites, 
and  the  continuation  of  the  Calami tes,  C.  Suckovi;  also,  the  occurrence  of 
Cycads  of  the  Permian  genus  Baiera,  and  of  the  remarkable  Conifer  of  the 
Yew  family,  of  the  new  genus  Saportcea,  whose  leaves  were  nearly  four  inches 


1117. 


1117-1121. 


1118. 


1117  a. 


MOLLUSKS.  —  Fig.  1117,  HIT  a,  Pseudomonotis  Hawni;  1118,  Myalina  perattenuata ;  1119,  Bakewellia  parva; 
1120,  Pleurophorus  subcuneatus  ;  1121,  an  undetermined  Gastropod.    Meek. 

wide.  Only  20  per  cent  of  the  species  have  been  found  in  the  Coal-measures, 
and  over  25  per  cent  occur  in  the  Permian  of  Europe,  and  the  genus  Cymo- 
glossa  is  confined  abroad  to  the  Permian. 

ANIMALS. — 1.  Brachiopods,  1122. 

Mollusks.  —  Many  of  the  com- 
mon Coal-measure  species  con- 
tinue on  into  the  Permian. 
Some  of  these  are :  Productus 
semireticulatus,  P.  Rogersi, 
Chonetes  Fleming!,  Spirifer 
cameratus,  Seminula  (Athyris) 
subtilita;  and  with  these  are 
others  confined  to  the  Permian, 
as  Meekella  (Orthisina)  Shu- 
mardana,  Productus  Norwoodi, 
Monotis  Halli,  M.  speluncaria, 
M.  variabilis,  Pseudomonotis 
Hawni  var.  ovata  (Fig.  1117), 
Myalina  perattenuata  (Fig. 
1118),  M.  Permiana,  M.  Halli, 
M.  recta,  Bakewellia  parva 
(Fig.  1119),  Pleurophorus  sub- 
cuneatus (Fig.  1120),  Schizodus  Rossicus,  Nautilus  eccentricus,  N.  Permianus, 
Cyrtoceras  dorsatum;  and  Texas  has  afforded  C.  A.  White  five  species  of 


Medlicottia  Copei.    C.  A.  White. 


686 


HISTORICAL   GEOLOGY. 


Nautilus,  a  Goniatites,  a  species  of  Medlicottia  (Fig.  1122),  and  other  Ammon- 
ites of  the  genera  Ptychites,  Popanoceras,  and  Wdagenoceras,  which  are 
Permian  in  Russia  and  India. 

2.  Crustaceans,  Insects.  — A  Trilobite,  of  the  genus  Phillipsia,  has  been  ob- 
served in  the  Permian  of  Missouri  (Swallow);  and  a  Cockroach,  Gerablattina 
balteata  Scudd.,  in  West  Virginia  and  Ohio  beds. 

1123. 


1123  a. 


AMPHIBIAN.  — Eryops  megacephalus  (x  J).     Cope,  '81. 


3.  Vertebrates.  — To  Fishes  and  Amphibians  the  Permian  beds  of  America, 
like  those  of  Europe,  added  Reptiles. 


PALEOZOIC   TIME CARBONIC.  687 

The  Fishes  were  of  Coal-measure  types  of  Ganoids  and  Selachians.  The 
genera  of  the  former  included  Ctenodus,  Ptyonodus,  and  others ;  also  Cerato- 
dus,  a  Dipnoan  genus,  which  here  has  its  first  known  species,  while  its  last  is 
still  living  in  Australia ;  the  Permian,  C.  favosus  of  Cope,  is  from  Texas. 
Sharks  occurred  of  the  genus  Diplodus,  and  along  with  them  spines  of  Ortha- 
canthus,  which  have  been  shown  to  have  belonged  to  Diplodus,  as  suggested 
by  Dawson  in  1869  from  the  association  of  specimens  in  the  Pictou  coal- 
field, Nova  Scotia. 

The  Amphibians  were,  like  the  earlier,  mostly  Stegocephs.  Fig.  1123  of 
the  cranium  of  Eryops  megacephalus  of  Cope,  from  Texas,  shows  that  the 
head  had  the  well-roofed  character  to  which  the  name  Stegoceph  alludes ; 
and  the  length  of  the  cranium,  over  22  inches,  indicates  a  large  species. 
Two  long,  narrow-headed  species,  Cricotus  heteroclitus  (Fig.  1124)  and  C. 

1124. 


AMPHIBIAN.  —  Cricotus  heteroclitus  (x  £).    Cope. 

Oibsoni  Cope,  have  been  found  in  the  Permian  of  Danville,  eastern  Illinois, 
and  the  former  also  in  northern  Texas. 

The  Permian  Beptiles,  the  earliest  of  the  class,  belong  to  the  tribe 
JRhynchocephalia,  which,  like  the  genus  Ceratodus  among  Fishes,  is  nearly 
extinct.  Only  two  species,  of  the  genus  Sphenodon  (or  Hatteria),  now  exist, 
and  these  are  confined  to  New  Zealand  —  a  piece,  like  New  Guinea,  of  a  now 
half-extinct  continent,  Australia.  One  of  the  earliest  of  the  species  is  proba- 
bly the  Mesosaurus  (Stereosternum)  tumidus  of  Cope  (Fig.  1125),  from  beds 
containing  shells  of  Schizodus  in  the  Permo-Carboniferous  of  Sao  Paolo, 
Brazil.  It  may  be,  however,  from  a  bed  below  the  Permian.  Cope  mentions 
its  relations  to  the  Amphibians  and  closer  to  the  Khynchocephalian  Reptiles, 
and  the  interesting  fact,  of  primitive  aspect,  that  the  foot,  as  the  figure  shows, 
has  a  tarsal  bone  (1  to  5  in  figure)  to  each  of  the  five  metatarsals  (I  to  V), 
five  in  all,  or  the  normal  number,  instead  of  four,  which  is  the  largest  number 
in  later  Reptiles. 

Other  Permian  reptiles,  but  probably  later  stratigraphically,  are  those 
of  Clepsydrops  of  Cope,  three  from  Texas  and  as  many  from  Illinois ;  of 


688  HISTORICAL   GEOLOGY. 

Dimetrodon  of  Cope,  which  has  several  Texas  species,  remarkable  for  the 
great  length  of  the  neural  spines  of  the  lumbar  vertebrae  which  supported  the 
broad  dorsal  fin  characteristic  of  the  genus ;  and  other  related  genera,  for 
which  Cope  instituted  the  family  of  Theromora  —  made  by  some  a  part  of 

1125. 


Mesosaurus  tumidus  (natural  size);  1-5,  tarsals  ;  I-V,  metatarsals.     Cope. 

the  group  Anomodontia.  Other  related  species,  from  New  Mexico,  are  the 
Ophiacodon  grandis  Marsh,  about  10  feet  long ;  also  species  of  Sphenacodon 
and  Notliodon  of  Marsh.  These  early  E/hynchocephalians  and  Anomodonts 
combine  Amphibian  and  Mammalian  characteristics  along  with  the  Keptilian. 

Characteristic  Species. 
1.  CARBONIFEROUS  PERIOD. 

PLANTS.  —  1.  Seaweeds  are  rare  in  the  Coal-measures.  A  Spirophyton,  like  S.  cauda- 
galli  (page  582),  has  been  reported  by  Lesquereux  as  occurring  in  sandstone,  probably  of 
this  era,  or  of  the  Subcarboniferous,  in  Crawford  County,  Ark.  Species  of  the  genus 
Caulerpites  have  been  observed  in  Pennsylvania,  Illinois,  Indiana,  Missouri,  in  both  the 
Lower  and  Upper  Coal-measures.  Chondrites  Colletti  Lsqx.  was  obtained  near  Lodi,  Ind., 
overlying  a  thin  coal-bed  at  the  base  of  the  Coal-measures.  Lesquereux  remarks  that, 
although  the  iron-stone  concretions  have  preserved  the  most  delicate  parts  of  Ferns  and 
Insects,  no  trace  of  a  Fungus  or  Lichen  has  been  found  in  them.  He  observed  elsewhere, 
however,  evidences  of  parasitic  Fungi.  A  large  Fungus,  having  some  resemblance  to  an 
Agaricus,  has  been  reported,  with  illustrations,  by  H.  Herzer,  from  the  Lower  Kittanning 
coal-bed  of  Tuscarawas  County,  Ohio,  and  named  Dactyloporus  archceus. 

2.  Lepidodendrids. — Fig.  1033,  part  of  the  surface  of  the  Lepidodendron  aculeatum 
Sternb.,  a  common  species  both  in  the  United  States  and  in  Europe  ;  1034,  L.  clypeatum 
Lx.  ;  1036,  L.  Veltheimanum  St.,  which  is  also  Subcarboniferous  and  European ;  1035, 
Halonia  pulchella  Lx.,  Arkansas.     Other  common  species,  and  of  wide  range,  are  Lepi- 
dodendron Sternbergii  (also  Subcarboniferous),  L.  dichotomum  Brgt.,  L.  modulatum  Lx. 

3.  Sigillarids.  —  Fig.  1037,  Sigillaria  Sillimani Brgt. ,  Pa.,  Ind. ;  1038,  8.  Pittstonana 
Lx.,  Pittston,  Pa.,  Ky. 


PALEOZOIC   TIME  —  CARBONIC.  689 

4.  Ferns.  —  Fig.  1042,  scar  of  the  Tree-fern,  Stemmatopteris  punctata  Lx.,  Gate  vein, 
Pa. ;  1043,  same  of  Megaphyton  McLayi  Lx.,  111.  ;  1044,  scar  of  Cyathea  compta,  a  species 
now  growing  in  the  islands  of  the  Pacific ;  1045,  Odontopteris  Schlotheimi  Brgt.,  Pa. ,  Ohio, 
111.,  Europe  ;  1046,  Alethopteris  lonchitica  Brgt.,  most  common  in  the  Lower  Coal-measures, 
Pa.,  etc.  ;  1047,  Sphenopteris  (Hymenophyllites)  HildrethiljX.,  Kanawha  Salines;  1047  a, 
same,  enlarged  ;  1048,  JS.  Gravenhorstii  Brgt.,  R.  I.,  Mo. ;  1048  a,  same,  enlarged  ;  1049,  a, 
Neuropteris  Loschii  Brgt. ,  and  1050,  Neuropteris  hirsuta  Lx. ,  from  figures  by  Lesquereux, 
common  in  the  Upper  Coal-measures,  in  Ohio  and  Kentucky,  and  the  former  particularly 
abundant  in  the  Pomeroy  bed  ;  1051,  Pecopteris  arborescens  Brgt.,  Pa.,  Ohio  ;  P.  cyathea 
Brgt.  and  P.  unita  Brgt.,  common  ;  1052,  Neuropteris  tenuifolia  Lx.,  Shamokin,  Pa.     In 
Arctic  America,  on  Melville  Island,  impressions  of  a  Sphenopteris  have  been  observed  in 
connection  with  the  coal. 

5.  Calamitids. — Fig.  1056,  Calamites  cannceformis  Schloth.,  Potts ville  conglomerate 
and  Lower  Coal-measures  ;  1054,  Asterophyllites  sublcevis  Lx. ;  1053,  A.  equisetiformis  Lx., 
Pa.,  R.  I.  ;  1055,  Sphenophyllum  Schlotheimi  Brgt.,  through  all  the  Coal-measures. 

6.  Gymnosperms.  —  Cordaites  borassifolius  Ung.,  a  common  Coal-measure  species; 
Fig.  1057,  Cordaites  costatus,  Lx. ,  Cannelton,  Pa.  ;  1057  a,  fruit  of  same  ;  1062,  Cordaicar- 
pus  Gutbieri  d'Eury,  Cannelton  ;  1063,   Cardiocarpus  elongatus  Newb.,  Ohio ;  1065,   C. 
bisectus  Dn.,  Nova  Scotia;  1064,  C.  samarceformis  Newb.,  Ohio;  1058  a,  b,  c,  Trigono- 
carpus  tricuspidatus  Newb.,  Ohio,  representing  the  rind,  the  nut,  and  the  kernel;  1059, 
nut  of  another  Ohio  species,  figured  by  Newberry,  but  not  described ;  1060,  a,  T.  ornatus 
Newb.,  Ohio  ;  1061,   Cardiocarpus  bicuspidatus  Newb.,  Ohio.      Figs.  1066  and  1067  are 
made  the  type  of  the  genus  of  Conifers,  Botryoconus  of  Grand'Eury,  being  immature 
fruits.     The  specimens,  and  that  of  the  fruit,  Fig.  1068,  are  from  the  Lower  Coal-measures 
of  Youngstown,  Ohio. 

The  Rhode  Island  coal  region,  according  to  Lesquereux,  belongs  to  the  Upper 
Productive  Measures.  See  Am.  Jour.  Sc.,  xxxvii.,  229,  1889. 

For  lists  of  species  of  plants  characteristic  of  the  several  subdivisions  of  the  Carbo- 
niferous period,  and  their  geographical  distribution  in  America,  see  Lesquereux's  Penn- 
sylvania Report,  No.  P,  page  855  and  beyond,  and  also  page  636.  According  to  Lesquereux 
the  following  species  commence  in  the  Pottsville  conglomerate,  or  the  beds  next  above, 
and  continue  through  the  Coal-measures :  — 

The  names  of  species  not  in  the  Conglomerate  have  a  dash  before  them ;  those 
which  have  a  dagger  after  them  continue  into  the  Permian ;  and  those  starred  are  also 
European. 

Calamites  Suckovi  t*,  C.  ramosus  *,  C.  cannceformis  *,  C.  approximatus  *,  C.  Cistii  *  ; 
Asterophyllites  equisctiformis*,  A.  foliosus*,  Annularia  longifolia  t*,  — A.  sphenophyl- 
Zoidesi*,  Sphenophyllum  Schlotheimi*,  S.  longifoUum^,  — 8.  emarginatum*,  Neuropteris 
hirsuta  t*,  N.  flmbriata  t,  N.  inflata,  — N.  angustifolia*,  N.  Loschii*,  N.  tenuifolia*,  N. 
capitata,  N.  Germari*,  — N.  cordata t*,  Odontopteris  Schlotheimi*,  0.  sphenopteroides  ; 
Alethopteris  Serlii*,  A.  lonchitica* ;  Pseudopecopteris  nervosa,  P.  muricata*,  P.  anceps, 
P.  irregularis*,  P.  nummularia  *,  P.  decipiens,  P.  latifolia*;  Pecopteris  acuta*,  P.  serrulata, 
— P.  arborescens^*,  — P.notatri,  P.pteroides^*,  P.  erosa* ;  Sphenopteris  (Hymenophyllites) 
spinosa*,  S.furcata*,  S.  tridactylites * ;  Ehacophyllum  lactuca]*,  E.filiciforme* ; — Lepi- 
dodendron  Sternbergii*,  L.  aculeatum,  L.  Veltheimanum*,  L.  vestitum,  L.  clypeatum, 
L.  dichotomum*,  L.  obovatum*,  L.  modulatum,  L.rimosum* ;  Ulodendron  majus*,  — U. 
punctatum;  Knorria  imbricata*;  Lepidophloios  laricinus* ;  Sigillaria  monostigma,  S. 
Brardii  t*,  — 8.  Menardi*,  S.  tesselata  *,  S.  mammillaris  t,  S.  Lescurii,  — Cordaites diversi- 
folius,  C.  borassifolius* 

The  genera  especially  characterizing  the  Lower  Coal-measures  are :  Megalopteris, 
Tceniopteris,  Neriopteris,  Hymenophyllites  section  of  Sphenopteris,  Eremopteris,  Knorria, 
Lepidophloios,  Lepidodendron,  Sigillaria,  Cordaites,  Whittleseya. 
DANA'S  MANUAL  —  44 


690  HISTORICAL   GEOLOGY. 

For  Reports  on  American  coal  plants  with  figures,  see  Indiana  Geol.  Hep.  for  1883,  by 
Lesquereux ;  Illinois  Geol.  Rep.,  vols.  ii.  and  iv.,  by  Lesquereux  ;  Ohio  Pal.,  vols.  i.  and 
ii.,  by  Newberry  ;  Pennsylvania  Geol.  Rep.,  No.  P,  by  Lesquereux,  1st  vol.  text,  2d  vol. 
plates,  3d  vol.  text  and  plates,  1880-84. 

On  the  Permian  flora,  see  Fontaine  and  White,  Pa.  Geol.  Hep.,  No.  PP,  1880. 

ANIMALS.  —  1.  Rhizopods.  —  Fig.  1069,  Fusulina  cylindrica  of  Fisher,  is  a  Russian  spe- 
cies, to  which  the  American  specimens  in  part  are  referred.  F.  elongata  Shumard,  F.  robusta, 
F.  ventricosa,  and  F.  gracilis  of  Meek,  are  supposed  to  be  probably  varieties  of  it.  Loftu- 
sia  Columbiana  G.  M.  Dawson,  Q.  J.  G.  S.,  xxxv.,  74.  Dentalina  priscilla  Dn.,  from  Nova 
Scotia,  consists  of  a  single  series  of  cells. 

2.  Actinozoans.  —  Syringopora    multattenuata    McCh.,     Campophyllum     torquium 
Ow.,  etc. 

3.  Echinoderms.  —  Crinoids,  of  the  genera  Poteriocrinus,  Actinocrinus,  Cyathocrinus, 
Zeacrinus,  Delocrinus,  Scaphiocrinus,  Eupachycrinus,  Agassizocrinus,  Acrocrinus,  etc. 

4.  Molluscoids.  —  Fig.  1072,  Spirifer  cameratus  Mort.,  Lower  and  Upper  Coal-meas- 
ures, in  Ohio,  Ky.,  Ind.,  111.,  Mo.,  Utah,  etc.  ;  1070,  Productus  Nebrascensis  Ow.,  111.,  Kan., 
N.  Mex.  ;  1071,  Chonetes  mesolobus  N.  &  P.,  a  common  species  ;  1073,  Seminula  subtilita 
Hall,  common  in  the  Coal-measures  ;  Spiriferina  Kentuckensis  Upper  Coal-measures,  111., 
Ky.,  Mo.,  and  near  Pecos  village,  N.  Mex.;  Spirifer  lineatus  Phill.,  Meekella  striatocostata 
Cox,  111.,  Mo.,  Iowa;   Orthis  Pecosi  Marcou;  Dielasma  (Terrebratula)  bovidens  Mort.; 
Derby  a  (Streptorhynchus)  crassa  M.  &  H.  ;     Waldheimia  ?  (Cryptacanthia)   compacta 
W.  &  St.  John.     The  following  first  appeared  in  the  Subcarboniferous,  and  are  continued 
into  the  Carboniferous :  Productus  punctatus  (Fig.  1013,  page  642),  P.  cora,  P.  muricatus, 
P.  semireticulatus  (Fig.  423,  page  427),  Spirifer  lineatus. 

5.  Mollusks.  —  Lamellibranchs. — Fig.  1074,  Macrodon  carbonarius  M.,  Upper  Coal- 
measures,  Ky.  ;  1075,  Allorisma  subcuneata  M.  &  H.,  Kan.  ;  Aviculopecten  rectilaterarius 
Cox,  Upper  and  Lower,  Avicula  (Gervillia)  longa  M.,  Nuculana  bellistriata  M.,  Cardio-  j- 
morpha  Missouriensis  Shum.,  Solenomya  radiata  M.  &  W.,  Myalina  perattenuata  M.  &  H.,  ' 
M.  recurvirostris  M.  &  W.,  Schizodus  amplus  M.  &  W.,  all  from  111.     Entolium  avicula 
Swallow,  Kan.  ;  Pinna  peracuta  Shum.,  Mo.,  Kan.  ;  Lima  retifera  Shum.,  Kan. ;  Mytilus 
[Modiola  (?)]   Shawneensis  Shum.,  Kan.  ;  Monodon,  species  of  Monopteria,  Pseudomo- 
notis,  Placunopsis,  etc.;  Modiola  Wyoming  ensis~Lz&,  Wyoming,  Pa.;  Anthracomya  (Naiad- 
ites)  carbonaria  Dn.,  N.  Scotia ;  A.  elongata  Dn.,  N.  Scotia  ;  A.  Icevis  Dn.,  N.  Scotia. 

6.  Gastropods.  —  Fig.  1077,  Bellerophon  carbonarius  Cox  (often  referred  to  B.  Urii 
Fleming),  Upper  Coal,  Ky.  ;  1076,  Pleurotomaria  tabulata  Con.  ;  1078,  P.  sphcerulata  Con. ; 
P.  carbonaria  N.  &  P.,  P.  Graymllensis  N.  &  P.  ;  1079,  Macrocheilus  (?)  fusiformis  H.,  M. 
Newberryi  Stevens,  M.  ventricosus  H.,  Iowa,  Mitrchisonia  minima  Swallow,  Mo.  ;  1080, 
Dentalium  sublceve   H.,   D.  Meekanum  Gein.,  Neb.  and  111.  ;    Straparollus  pernodosus 
M.  &  W.,  111.  ;    Chiton  carbonarius  Stevens,   Straparollus  subrugosus  M.  &  W.,   111., 
Loxonema  semicostatum  M.,  Aclis  robusta  Stevens,  Streptaxis   Whitjieldi  M.,  all  from 
Illinois ;  Naticopsis.     Also  the  Land-snails  (Helix  family),  Fig.  1081,  Pupa  vetusta  Dn., 
half  an  inch  long,  Coal-measures,  Joggins,  N.  Scotia  ;  1082,  Pupa  Vermilionensis  Bradley, 
Vennilion  County,  111.,  in  a  concretionary  limestone ;  1083,  Dawsonella  Meeki  Bradley, 
same  locality. 

For  Cephalopods  of  the  Carboniferous,  see  papers  by  Shumard,  McChesney,  Swallow, 
Hall,  Hall  and  Whitfield,  and  the  Geological  Reports  of  Illinois  (Meek  and  Worthen), 
Missouri  (Swallow),  Texas  (Hyatt). 

Some  of  the  Nautiloids  of  the  Carboniferous,  part  of  them  new  species,  as  named  and 
figured  by  Hyatt  in  the  second  Annual  Texas  Geological  Report  are :  Temnochilus  con- 
chiferum,  Tex.  ;  T.  Forbesanum,  Tex.  (Nautilus  F.  of  McChesney);  T.  latum,  Meek  and 
Worthen,  Kan. ;  T.  depressum,  Kan. ;  T.  crassum,  Kan.  ;  Metacoceras  cavatiforme,  Kansas 


PALEOZOIC   TIME  —  CARBONIC.  691 

City,  Mo.  ;  M.  dubium,  Kan.  ;  M.  Walcotti,  Tex.  ;  M.  Hayi,  Kan.  ;  M.  inconspicuum, 
Kan.  ;  Tainoceras  cavatum,  Tex.  ;  Domatoceras  umbilicatum,  Kan. ;  Asymptoceras  New- 
toni,  Kan.  ;  A.  capax  (Cryptoceras  capax,  Meek  and  Worthen),  Mo. ;  Phacoceras  Dumbli, 
Tex. ;  Ephippioceras  divisum  (Nautilus  divisus  of  White  and  St.  John) ;  Endolobus  gib- 
bosus,  Tex.  They  are  mostly  large  species,  4  to  6  inches  in  diameter. 

7.  Worms.  —  Fig.  1086,  Spirorbis  carbonarius  Dn.  ;  also,  S.  arietinus  Dn. 

8.  Limuloids.  —  Fig.  1088,  Prestwichia  Dance  =  Euproops  Dance  of  M.  &  W.,  Morris, 
111.;  P.   longispina  Packard,  Pittston,  Pa.;  Dipeltis  diplodiscus  Packard,  Mazon  Creek, 
111.;  Cyclus  Americanus  Packard,  Mazon  Creek,  111.  (Mem.  Nat.  Acad.  Sc.,  iii.,  14,  1888). 

9.  Crustaceans.  —  (a)  Trilobites.  —  Phillipsia  Missouriensis,  P.  major,  P.  Cliftonensis 
of  Shumard,  from  the  Upper  Coal  of  Missouri ;  P.  (Griffithides)  scitula  M.  &  W.,  111.,  Ind., 
and  Neb. ;  P.  (Griff.)  Sangamonensis  M.  &  W.,  Upper  Coal,  111. 

(b)  Entomostracans. —  Cythere  Americana  Shum.,  Upper  C.,  Mo.;  Leaia  tricarinata 
M.  &  W.,  Upper  Coal-measures,  111.;  Dithyrocaris  carbonaria  M.  &  W.,  111.;  Ceratiocaris 
sinuata  M.  &  W.,  111. 

(c)  Decapods.  — Tig.  1089,  Acanthotelson  Stimpsoni  M.  &  W.,  Morris,  HI.;  A.  Event 
M.  &  W.,  Morris,  111.;  1090,  Palceocaris  typus  M.  &  W.,  Morris,  111.;  1091,  Anthraco- 
palcemon  gracilis  M.  &  W.,  Morris,  111.;  A.  Hillanus  Dn.,  N.  Scotia. 

10.  Myriapods.  —  Mazon  Creek,  111.,  has  afforded  species  of  a  dozen  genera,  including 
Palceocampa  anthrax  M.  &  W.,  Acantherpestes  major  M.  &  W.,  Euphoberia  armigera 
M.  &  W.,  and  10  other  species  of  the  genus  ;  Anthracerpes  typus  M.  &  W.,  Eileticus  anthra- 
cinus  Scudder,  Xylobius  Mazonus  Sc.,  Trichiulus  villosus  Sc.,  and  others  of  Archiulus, 
llyodes,  etc.     In  Nova  Scotia  have  been  found  Xylobius  sigillarice  Dn.  (Fig.  1092),  JT. 
fractus  Sc.,  X.  similis  Sc.,  Archiulus  Dawsoni  Sc.,  A.  Lyelli  Sc.,  A.  euphoberioides,  and 
others. 

11.  Arachnids.  —  Besides  the  Scorpion  of  Fig.  1094,  Mazon  Creek  has  afforded  Mazonia 
(Eoscorpius)  Woodiana  M.  &  W.,  Architarbus  rotundatus  Sc.,  allied  to  the  Phalangidse, 
Arthrolycosa  antiqua  Harger  (Fig.  1095),  Geraphrynus  carbonarius  Sc.,  the  long-tailed 
Geralinura  carbonaria  Sc.     From  Arkansas  has  come  Anthracomartus  trilobitus  Sc.  ; 
from  Rhode  Island,  another  species  of  Anthracomartus'  from  Nova  Scotia,  Mazonia 
Acadica  Sc. 

12.  Insects.  —  (a)  Neuropteroids.  —  From  Morris,  111.,  Miamia  Bronsoni  D.,  Hemeris- 
tia  occidentalis  D.,  Chrestotes  Dance  Brgt.,  C.  lapidea  Sc.,  Megathentomum  pustulatum 
Sc.,  Genentomum  validum  Sc.,  Anthracothremma  robusta  Sc.,  and  others.     From  Pittston, 
Pa.,  species  of  Dieconeura  and  Polyernus. 

(6)  Orthopteroids.  —  Of  the  Cockroach  group  there  have  been  found :  at  Mazon  Creek,  4 
species  of  Mylacris,  2  of  Promylacris,  2  of  Paromylacris,  1  of  Archimylacris,  2  of  Etoblat- 
tina, 1  of  Progonoblattina,  and  1  of  Oryctoblattina  ;  in  Pennsylvania,  6  of  Mylacris,  2  of 
Neomylacris,  1  of  Archimylacris,  3  of  Lithomylacris,  1  of  Promylacris,  1  of  Etoblattina, 

1  of  Gerablattina  ;  at  Cassville,  W.  Va.,  6  of  Etoblattina,  15  of  Gerablattina,  1  of  Anthra- 
coblattina,  3  of  Poroblattina,  and  1  of  Petrablattina ;  at  Richmond,  Ohio,  17   of  Eto- 
blattina, 3  of  Gerablattina,  and  2  of  Poroblattina  ;  near  Providence,  R.  I.,  8  of  Etoblattina, 

2  of  Gerablattina,  and   1  of  each  Mylacris  and  Microblattina  /  and  a  few  others  in 
Missouri,  Kansas,  Arkansas,  Nova  Scotia,  and  Cape  Breton.     Orthopters  of  the  Proto- 
phasmid  type  occur  at  several  of  the  above  localities. 

Of  Carboniferous  Hemipteroid  Insects,  which  are  not  uncommon  in  Europe,  a  species, 
Phthanocoris  occidentalis,  occurs  near  Kansas  City,  Mo.  Of  Coleopteroid  Insects,  no 
American  species  have  yet  been  reported. 

The  above  lists  of  fossil  Myriapods,  Arachnids,  and  Insects  are  from  Mr.  Scudder's 
publications  and  correspondence.  See  his  Bulletin  No.  31,  U.  S.  G.  S.,  for  a  review  of  the 
subject  up  to  1886  ;  also,  Bulletin  No.  71,  1891,  for  a  full  index  by  him  to  the  known  fossil 


692  HISTORICAL   GEOLOGY. 

Myriapods,  Arachnids,  and  Insects  of  the  world,  with  references  to  all  published  papers 
and  works  on  the  subject,  covering  744  octavo  pages. 

13.  Vertebrates. — (a) Fishes.  —  Ganoids.  J?ig.llQQ,EurylepistuberculataNev?l).;  1101, 
Ccelacanthus  elegans  Newb.,  Linton,  Ohio,  remarkable  for  not  having  the  tail  heterocercal, 
although  strictly  vertebrated ;  8  other  species  of  Eurylepis,  2  of  Ccelacanthus,  and  3  of 
RMzodus,  have  been  described  by  Newberry  from  Linton,  also  Palceoniscus  scutigerus 
and  P.  peltigerus  Newb.,  Ohio  ;  P.  Leidyanus  Lea,  Pa. ;  P.  gracilis  N.  &  W.,  111.;  P.  Browni 
of  Albert  Coal  Mine,  N.  B. ;  P.  Jacksoni  Dn.  Other  Ganoids  occur,  of  the  genera  Mega- 
lichthys,  Amblypterus,  Pygopterus,  and  Rhadinichthys,  in  the  Coal-measures  of  the  United 
States  and  Nova  Scotia. 

Among  Selachians,  the  following  European  genera  have  been  recognized  in  the  Coal- 
measure  limestones  of  Pennsylvania,  Ohio,  Indiana,  Illinois,  etc.,  —  the  species  being  gen- 
erally distinct  from  those  of  the  Old  World :  Diplodus,  Cladodus,  Orodus  ;  Diplodus  com- 
pressus  Newb.,  Linton,  Ohio;  D.  latus  Newb.,  ibid.;  D.  gracilis  Newb.,  ibid.;  Petalodus, 
Ctenoptychius,  Chomatodus ;  Fig.  1102,  Petalodus  destructor  N.  &  W.,  from  Illinois  ;  1104  a, 
1104  &,  Petrodus  occidentalis  N.  &  W.,  from  Illinois,  Indiana,  etc.;  1103,  fin-spine  found 
associated  with  the  scales  of  Petrodus  occidentalis,  and  referred  by  F.  H.  Bradley  to  the 
same  species.  Cholodus,  Peltodus,  Calopodus,  Ctenoptychius  are  other  genera.  Of  fin- 
spines,  there  are  Orthacanthus  arcuatus  Newb.,  Linton;  Compsacanthus  Icevis  Newb., 
Linton;  Drepanacanthus  anceps  N.  &  W.,  from  Springfield,  111.,  and  others. 

The  genera  of  the  Subcarboniferous  are  in  part  represented  among  the  Carboniferous 
species,  as  Diplodus,  Orodus,  Cladodus ;  Petalodus  (Fig.  1102,  P.  destructor  N.  &  W., 
111.),  Petrodus  (Fig.  1104  a,  b,  P.  occidentalis,  N.  &  W.,  Ill,  Ind.,  etc.),  Ctenoptychius, 
Chomatodus,  Deltodus,  Pcecilodus,  Xystrodus.  Besides,  there  are  4  species  of  Agassizo- 
dus,  all  from  the  Coal-measures.  Also  fin-spines  of  the  genera  Compsacanthus,  Drepana- 
canthus, etc.  For  figures  and  descriptions  of  fossil  species  the  most  important  volumes 
are  those  of  the  Ohio  Geological  Report  by  Newberry,  and  those  of  the  Illinois  Report  by 
Newberry  and  Worthen  and  St.  John  and  Worthen. 

(6)  Amphibians.  —  Fig.  1109,  Pelion  Lyelli  Wyman,  Linton,  Ohio  ;  Fig.  1108,  Amphi- 
bamus  grandiceps  Cope,  Morris,  111.;  Fig.  1110,  vertebrae  and  ribs  from  Linton,  figured  by 
Wyman,  but  not  named,  referred  by  Cope  doubtingly  to  the  snake-like  Molgophis  macrurus 
Cope.  Baphetes  planiceps  Owen,  from  Pictou,  N.S.;  the  specimen  is  a  portion  of  the  skull 
7  inches  broad.  The  genera  Phlegethontia  and  Molgophis  of  Cope  are  referred  to  Dolicho- 
soma  of  Huxley  by  Fritsch.  For  descriptions  and  figures  of  the  species  of  Ohio,  see  Geol. 
Rep.,  Pal.  ii. ;  of  Nova  Scotia,  Dawson's  Acad.  GeoL,  and  its  supplement  of  1878,  the 
latter  containing  also  figures  of  Insects,  Crustaceans,  and  Myriapods  ;  also  Supplement  of 
1891,  and  later  in  the  Trans.  Roy.  Soc.  The  Linton  layer  in  Ohio  is  a  local  formation  of 
cannel  coal  at  the  bottom  of  the  Pittsburg  coal-bed,  indicating,  as  Newberry  states,  lake- 
like  conditions  during  the  progress  of  the  layer.  Twenty-three  consecutive  footprints  of  an 
Amphibian,  Thenaropus  heterodactylus,  were  found  by  A.  T.  King,  near  Westmoreland, 
Pa. ,  in  a  layer  about  100'  below  the  horizon  of  the  Pittsburg  coal ;  the  tracks  of  the 
hind-feet  5-toed,  and  of  the  fore-feet  4-toed,  — the  former  5i  inches  long,  and  the  latter 
4}  inches  ;  and  the  distance  between  the  successive  tracks  6  to  8  inches,  and  between  the 
2  lines  about  the  same.  Another  species  from  the  same  region  is  the  Chirotherium  Reiteri 
of  Moore. 

2.   PERMIAN  PERIOD. 

On  the  Permian  Flora  of  West  Virginia,  etc.,  see  Fontaine  and  White,  I.e.]  contains 
38  plates.  The  following  are  the  Coal-measure  species  which  continue,  according  to  these 
authors,  into  the  Permian  or  Upper  Barren  Measures  of  West  Virginia  and  Pennsylvania : 
Calamites  Suckovi,  Sphenophyllum  filiculme,  Annularia  longifolia,  A.  sphenophylloides, 
Neuropteris  hirsuta,  N.  flexuosa,  N.  auriculata,  N.  cordata,  Pecopteris  arborescens,  P. 


PALEOZOIC    TIME  —  CARBONIC.  693 

Candolleana,  P.  pteroides,  P.  dentata,  P.  notata,  P.  oreopteridea,  P.  Miltoni,  P.  Plucke- 
neti,  Goniopteris  emarginata,  G.  elegans(?},  G.  arguta(?},  Rhacophyllum  lactuca,  Sig- 
illaria  Brardii.  Of  these  species,  all  but  Sphenophyllum  filiculme,  Neuropteris  hirsuta 
and  Pecopteris  notata  are  also  European  Permian  species.  The  genera  Baiera  and  Callip- 
teridium  commence  in  the  Permian.  Out  of  107  species  of  plants  in  the  Upper  Barren 
Measures  of  West  Virginia,  28  are  European  Permian  species. 

The  Red-beds  of  South  Park,  near  Fairplay,  Col. ,  have  afforded  Permian  species  of 
Walchia,  Callipteris,  Odontopteris,  Sphenopteris,  Ullmannia,  etc.  (Lesquereux,  Bull.  Mus. 
Comp.  ZooL,  viL,  No.  8). 

On  Amphibians  and  Reptiles  of  Texas  and  Illinois,  Cope,  Amer.  Phil.  Soc.  for  1877 
and  several  later  years,  and  also  Proc.  Acad.  N.  8.,  Philadelphia,  Amer.  Naturalist  Bull., 
vi.,  Hayden  Surv.,  1881,  and  publications  of  Texas  Geological  Survey. 


FOREIGN. 

1.   SUBCAKBONIFEROUS   AND   CARBONIFEROUS   PERIODS. 
ROCKS  — KINDS  AND  DISTRIBUTION. 

The  rocks  of  the  Subcarbonif erous  and  Carboniferous  periods  cover  a  very 
large  area  in  the  western  half  of  Kussia,  or  the  Continental  Interior  of 
Europe,  much  of  the  area  of  Great  Britain  and  Ireland,  a  moderately  large 
area  on  the  borders  of  Belgium,  France,  and  Prussia,  and  small  areas  in 
Spain,  Italy,  Austria,  and  some  other  parts  of  Europe.  The  beds  of  the 
Carboniferous  period — the  period  of  the  Coal-measures  —  have  their  greatest 
thickness  and  largest  amount  of  coal  in  the  British  Isles,  and  but  little 
thickness  and  little  coal  in  Eussia.  There  are  workable  coal-beds  of  this  era, 
if  the  Permian  be  included,  also  in  China,  India,  and  Australia,  but  none,  so 
so  far  as  known,  in  South  America,  Africa,  or  Asiatic  Russia. 

The  proportion  of  coal-beds  to  area  in  different  parts  of  Europe  has  been 
stated  as  follows  :  in  France,  y^-  of  the  surface ;  in  Spain,  -fa ;  in  Belgium, 
^5-;  in  Great  Britain,  y1^.  But,  while  the  area  of  the  Coal-measures  in  Great 
Britain  is  about  12,000  square  miles,  it  is  in  Spain,  4000;  in  France,  about 
2000 ;  in  Belgium,  518. 

The  distribution  of  the  areas  in  England  is  shown  on  the  accompanying  map. 
The  cross-lined  black  areas  are  Subcarboniferous,  and  the  black  those  of  the 
Coal-measures.  The  principal  regions  of  the  latter  are  (1)  the  South  Wales, 
1000  square  miles  in  area ;  and,  in  nearly  the  same  latitude,  the  Forest  of  Dean, 
west  of  the  Severn,  and  the  region  about  Bristol,  east  of  the  Severn,  together 
184  square  miles ;  (2)  the  small  patches  in  central  England,  in  Shropshire 
(Coalbrook  Dale),  Warwickshire,  Leicestershire,  and  Staffordshire,  240 
square  miles ;  (3)  north  of  these,  on  the  west,  the  great  South  Lancashire 
region,  just  east  of  Liverpool,  with  the  basin  of  Flintshire  on  the  Dee,  the 
whole  together,  220  square  miles ;  (4),  to  the  eastward  of  the  last,  the  large 
Derbyshire  coal  region,  between  Nottingham  and  Leeds,  and  adjoining 
Sheffield,  800  square  miles ;  (5)  farther  north  on  the  west  coast,  in  Cumber- 
land, about  Whitehaven,  25  square  miles ;  (6)  on  the  east  coast,  the  great 


694 


HISTORICAL   GEOLOGY. 


coal-field  of  Northumberland  and  Durham,  about   Newcastle,   796   square 
miles. 

In  Scotland,  the  beds  cover  an  area  100  miles  long  by  25  broad,  lying  in 
the  depression  between  the  Grampian  range  on  the  north  and  the  Lammer- 


Fig.  1126,  Geological  map  of  England.  The  areas  lined  horizontally  and  numbered  1  are  Silurio-Cambrian ;  those 
lined  vertically  (2)  Devonian  ;  those  cross-lined  (3)  Subcarboniferous ;  the  black  areas  (4)  Carboniferous  ;  the 
dotted  areas  (5)  Permian ;  those  lined  obliquely  from  right  to  left  (6)  Triassic,  (7  a)  Lias,  (7  6)  Oolyte, 
(8)  Wealden,  (9)  Cretaceous ;  those  lined  obliquely  from  left  to  right  (10,  11)  Tertiary.  A  is  London ; 
B,  Liverpool ;  C,  Manchester ;  D,  Newcastle.  Ramsay. 

muirs  on  the  south.     The  most  of  the  workable  coal-beds  occur  in  the  Sub- 
carboniferous. 

In  Ireland,  over  its  center  and  to  the  southwest,  a  large  part  of  the 
surface  rock  is  Subcarboniferous  limestone.  It  is  believed  that  the  Coal- 
measures  once  covered  this  limestone. 


PALEOZOIC   TIME  —  CARBONIC.  695 

The  Subcarboniferous  rocks  of  Great  Britain  include  a  limestone  formation  called 
often  the  "  Mountain  limestone,"  and  also  shales  and  sandstone.  The  limestone  is  the  chief 
rock  in  southern  England,  where,  near  Bristol,  it  is  2000'  thick  and  has  shaly  beds  at  base, 
the  "Lower  limestone  shale."  In  Derbyshire,  the  limestone,  4000'  in  maximum  thickness, 
is  succeeded  by  a  series  of  shales  and  sandstones  with  beds  of  limestone,  called  the  Yore- 
dale  group.  This  Yoredale  group  is  2300'  thick  in  North  Staffordshire,  making  a  total 
thickness  of  6300';  it  is  4500'  thick  in  Lancashire.  In  Wales  the  thickness  of  the  lime- 
stone is  but  500',  and  in  Anglesey,  200'  to  500'. 

In  Scotland,  the  Subcarboniferous  rocks  are  mainly  fragmental,  and  are  called  the 
Calciferous  limestone  group. 

In  southwestern  Ireland,  the  limestone  has  a  thickness,  in  Limerick,  of  3600'.  But  in 
northern  Ireland,  the  fragmental  beds  increase  in  amount  and  thereby  become  similar  to 
those  of  Scotland,  as  if  they  were  their  continuation. 

In  Northumberland,  in  northern  England,  fragmental  beds  greatly  predominate  ;  the 
total  maximum  thickness  is  8000',  and  of  this,  only  20'  to  50'  is  limestone  ;  they  have 
received  a  distinct  name,  —  that  of  the  Bernician  group,  —  because  they  are  so  unlike  the 
rest  and  without  any  natural  subdivision ;  and  those  of  the  valley  of  the  Tweed  and  the 
vicinity  have  been  termed  the  Tuedian  group. 

The  Carboniferous  limestone  of  the  Lake  District  and  Yorkshire  was  called  the  "  Scar 
limestone"  by  Sedgwick,  from  the  topographic  features,  or  "scars"  produced  by  the 
rock.  It  makes  a  strong  impression  on  the  scenery  of  many  parts  of  England.  "  Massive 
beds  of  it,"  says  Prestwich,  "  rising  from  beneath  the  Mesozoic  strata  in  the  neighborhood 
of  Frome  and  Wells,  constitute  the  main  range  of  the  Mendips.  At  Clifton  it  is  traversed 
by  the  gorge  of  the  Avon.  A  few  miles  to  the  north  the  limestone  passes  under  the 
great  plains  of  central  England  to  reappear  in  the  picturesque  hills  of  Derbyshire,  the 
bluffs  of  Matlock,  the  scarps  of  Dovedale,  and  the  high  ridges  of  Buxton.  In  Yorkshire 
the  limestone  hills,  which  rise  to  heights  of  2000'  to  2500'  in  the  Pennine  chain,  are 
intersected  by  the  many  beautiful  dales  so  characteristic  of  that  district.  The  prevailing 
cold  gray  color  of  the  limestone,  the  frequency  of  bared  surfaces,  and  the  innumerable 
caves  —  famous  for  their  magnitude  and  their  stalactites,  or  as  the  dens  of  Pleistocene 
Mammals  —  render  the  rocks  easily  recognizable,  and  contribute  greatly  to  their  scenic 
effects."  The  limestone  contains  much  chert.  Hinde  has  shown  that  the  chert  abounds 
in  sponge-spicules  ;  and  Carter  has  observed  facts  illustrating  the  passage  by  solution  of 
the  spicules  into  chert. 

The  beds  of  the  Coal-measures  in  England  have  generally  at  bottom  the 
Millstone  grit,  answering  to  the  Pottsville  conglomerate  of  Pennsylvania. 
The  thickness  is  400  to  1000  feet  in  South  Wales,  about  1200  feet  in  the 
Bristol  coal-field,  3000  to  5000  feet  in  the  Lancashire  region ;  but  in  the 
north  of  England  only  500  feet,  and  in  Scotland  it  is  barely  recognizable. 

The  Coal-measures  in  South  Wales  have  a  thickness  of  7000  to  12,000  feet, 
and  include  more  than  100  coal-beds,  120  feet  in  total  thickness,  70  of  which 
are  worked.  While  the  coal  is  bituminous  near  Swansea,  it  becomes  anthra- 
cite to  the  west  and  north. 

In  the  Eorest  of  Dean,  the  thickness  of  the  beds  is  2400  feet,  and  they 
comprise  at  least  23  coal-beds  ;  while  in  the  Bristol  coal-field,  on  the  other 
side  of  the  Severn,  there  are  5090  feet  of  Coal-measures,  with  87  coal-beds. 

In  the  south  Lancashire  coal  region,  which  reaches  nearly  to  Liverpool, 
the  Coal-measures  are  stated  to  have  a  thickness  of  7200  to  8000  feet,  and  to 
include  more  than  40  beds  of  coal  over  one  foot  in  thickness,  and  in  north 


696  HISTORICAL   GEOLOGY. 

Staffordshire  the  thickness  is  8000  feet.  But  to  the  northward,  in  Derby- 
shire, the  thickness  is  about  2500  feet,  and  in  Northumberland  and  Durham, 
and  in  Scotland  2000  feet.  The  coal-beds,  as  elsewhere,  usually  rest  on  a 
bed  of  fire  clay  containing  rootlets.  In  the  Newcastle  region,  the  Coal-meas- 
ures are  about  2000  feet  thick,  and  include  about  60  feet  of  coal :  the  beds 
afford  about  a  fourth  of  the  coal  of  England. 

The  Lancashire  area  and  the  Cumberland  farther  north  lie  on  the  west 
side  of  an  anticlinal  ridge,  mostly  of  Subcarboniferous  and  Lower  Carbonif- 
erous rocks,  called  the  Pennine  chain,  in  some  points  2000  feet  high,  which 
extends  north  to  the  Cheviot  Hills,  between  England  and  Scotland.  The 
Derbyshire  and  Newcastle  areas  are  to  the  east  of  this  anticlinal. 

Prestwich  observes,  with  regard  to  a  parallelism  in  the  several  coal-beds, 
between  the  different  British  coal-fields,  and  between  these  and  European 
coal-fields,  that,  while  this  is  not  to  be  looked  for,  some  general  relations  may 
be  made  out.  The  great  dividing  mass  of  rock,  2000  to  3000  feet  thick, 
called  Pennant,  exists  in  both  the  Welsh  and  Bristol  coal-fields ;  and  the 
total  thickness  is  not  very  different  in  the  two  — about  10,500  feet  in  one  and 
8500  in  the  other,  with  76  coal-beds  in  Wales,  and  55  in  Somerset.  In  the 
Hainault  (or  Mons  and  Charleroi)  basin,  the  measures  are  9400  feet  thick, 
with  100  beds  of  coal ;  in  the  Liege  basin,  7600  feet,  with  85  beds ;  in  West- 
phalia, 7200  feet,  with  117  beds. 

In  Belgium,  in  the  region  of  the  Meuse,  the  Carboniferous  limestone  has  a  thickness 
of  nearly  2500',  and  includes  at  top  the  "Limestone  of  Vis6"  ;  800'  below  the  top,  the 
"  Dolomite  of  Namur  "  ;  and  2000'  below  the  top,  the  "  Limestone  of  Dinant." 

The  wide-spread  Subcarboniferous  formation  in  Kussia  is  chiefly  limestone.  To  the 
eastward,  at  the  west  base  of  the  Urals,  there  is  one  wide  north- and-south  belt,  and  another 
to  the  westward  extending  from  the  Arctic  Sea,  in  662°  N.,  to  54°  N.  Near  Moscow  the 
formation  was  reached  by  boring  through  the  Jurassic  and  underlying  beds. 

The  Carboniferous  limestone  has  been  found  by  Richthofen  to  underlie  a  large  coal 
region  in  China,  and  to  be  marked  by  Fusulina  and  other  fossils  of  the  European  Subcar- 
boniferous beds. 

The  Belgian  Coal-measures  of  Liege  and  Mons  extend  80  miles  along  the  northern 
flanks  of  the  Ardennes,  and  have  numerous  coal-beds,  the  thickest  3'.  The  principal  coal 
basin  of  Germany  is  that  of  Saarbriick  in  the  Rhenish  provinces,  900  square  miles  in  area. 
In  a  thickness  of  Coal-measures  of  nearly  20,000',  it  contains  82  workable  beds,  included 
mainly  in  the  lower  9000'.  Another  area  is  that  of  Westphalia.  Silesia,  in  a  coal  region 
16  miles  square,  has  one  coal-bed  50'  thick.  Some  anthracite-bearing  beds  occur  in  the 
western  Alps  among  schistose  crystalline  rocks,  but  none  of  economical  value.  The  chief 
Austrian  basin  is  in  Bohemia  at  Pilsen.  Russia  has  valuable  coal-beds  at  Donetz  on  the 
north  shore  of  the  Azof.  In  China,  plants  of  Carboniferous  age  have  been  obtained,  to 
the  north  in  the  peninsula  of  Manchuria,  where  coal-beds  are  worked,  and  also  in  the 
provinces  of  Shansi,  Hunan,  Pe-chi-li,  and  others  (Richthoferi1  s  China,  vols.  ii.  and  iv.). 
Carboniferous  Coal-measures  occur  also  in  Japan  and  Borneo. 

In  the  Arctic  seas,  Spitzbergen  has  a  coal  formation  well  developed,  but  no  beds  of 
coal.  The  Coal-measures  are  1000'  to  2000'  thick  in  Robert's  valley,  with  many  coal 
plants  in  the  shales  ;  and  the  Subcarboniferous  limestone  and  other  rocks  (which  probably 
pass  down  into  Devonian),  and  afford  fossil  Corals,  Crinoids,  and  Brachiopods  related  to 
European  and  American  species,  besides  plants ;  and  the  chert  has  been  reported  by 
Hinde  to  be  full  of  Sponge-spicules. 


PALEOZOIC   TIME  —  CARBONIC.  697 


2.   PERMIAN  PERIOD. 

On  the  map  of  England  (Fig.  1126)  a  border  of  Permian  is  represented 
along  the  east  side  of  the  Newcastle  Carboniferous  area,  and  also  adjoining 
other  coal  areas  excepting  that  of  South  Wales.  (The  areas  are  marked  with 
dots  on  a  white  ground,  and  numbered  5.)  A  small  area  occurs  in  Ireland, 
about  the  Lough  of  Belfast.  The  rocks  are  red  sandstone  and  marlytes, 
along  with  Magnesian  limestone.  Before  their  relations  were  correctly  made 
out,  they  were  included,  along  with  part  of  the  Triassic,  under  the  name 
"New  Red  Sandstone." 

In  Durham,  northeastern  England,  there  is  (1)  a  Lower  Red  sandstone, 
200  feet  thick ;  then  (2)  a,  60  feet  of  marl-slate ;  b,  two  strata  of  Magnesian 
limestone,  the  lower  500,  and  the  upper  100  feet  thick,  separated  by  200  feet 
of  gypseous  marlyte,  and  overlaid  by  100  feet  of  the  same.  The  Magnesian 
and  other  limestones  disappear  to  the  south,  near  Nottingham.  In  north- 
western England,  the  Lower  Permian  includes  3000  feet  of  marlytes  and 
sandstones;  the  Middle,  only  10  to  30  feet  of  Magnesian  limestone;  the 
Upper,  600  feet,  similar  to  the  Lower.  There  are  detached  Permian  areas  in 
Dumfriesshire,  Ayrshire,  etc.,  in  Scotland. 

In  European  Russia,  Permian  strata  cover  a  region  more  than  twice  as 
large  as  all  France;  it  includes  the  greater  part  of  the  governments  of  Perm, 
Orenburg,  Kazan,  Nizhni  Novgorod,  Yaroslavl,  Kostroma,  Viatka,  and 
Vologda.  The  beds  are  sandstones,  shales,  marlytes,  and  dolomitic  lime- 
stone, and  contain  an  occasional  thin  seam  of  coal.  The  deposits  are  flanked 
and  underlaid  on  nearly  all  sides  by  different  members  of  the  Carboniferous 
formation  containing  comparatively  little  coal. 

In  central  Germany  small  areas  occur,  from  southern  Saxony,  along  the 
Erzgebirge,  over  the  adjoining  small  German  states,  west  to  Hesse  Cassel, 
and  north  to  the  Harz  Mountains  and  Hanover.  Within  this  area,  Mans- 
feld  is  one  noted  locality,  situated  in  Prussian  Saxony,  not  far  from  Eisleben ; 
another  is  on  the  southwest  borders  of  the  Thuringian  forest  (Thuringer- 
wald)  in  Saxe-Gotha,  a  line  which  is  continued  to  the  northwest,  by  Eise- 
nach, toward  Miinden  in  southern  Germany.  In  Thuringia  and  Saxony,  the 
subdivisions  of  the  rocks,  beginning  below,  are  (1)  the  Eothliegende,  or  Red 
beds,  consisting  of  red  sandstone,  and  barren  of  copper  ores ;  near  the  town 
of  Eisenach,  about  4000  feet  thick ;  (2)  The  Zechstein  formation,  or  Mag- 
nesian limestone,  consisting  of  (a)  the  Lower  Zechstein,  a  gray,  earthy  lime- 
stone, overlying  the  Kupferschiefer,  or  copper-bearing  shales,  and  the  still 
lower  Weissliegende  or  Graulieyende,  or  white  or  gray  beds ;  (6)  the  Mid- 
dle Zechstein,  Magnesian  limestone,  called  the  JRauchwacke  and  Rauhkalk ; 
(c)  the  Upper  Zechstein,  or  the  Plattendolomit,  and  including  the  impure  fetid 
limestone  called  Stinkstein. 

The  lower  part  of  the  Lower  Permian  of  England  includes,  in  some  places, 
beds  of  coarse  conglomerate,  containing  angular  masses  of  rock  of  great  size. 


698  HISTORICAL   GEOLOGY. 

Eamsay  attributes  the  transportation  of  the  blocks  to  floating  ice.  Bowlders 
in  beds  of  great  thickness  and  coarseness,  glacial-like,  with  many  of  the 
bowlders  scratched,  occur  toward  the  bottom  of  the  Talchir  group  of  India, 
regarded  as  Lower  Permian;  in  equivalent  beds  of  the  Salt  Eange  of 
northern  India ;  in  the  related  Ecca  beds  of  South  Africa,  below  the  Karoo 
beds ;  in  beds  beneath  the  Glossopteris  Coal-measures  of  eastern  Australia, 
and  also  other  beds  overlying  the  same,  called  the  Hawkesbury  sandstone  ; 
and  also  in  Victoria  and  Queensland.  In  New  Zealand  similar  bowlder  beds 
are  referred  by  Dr.  Hector  to  the  Trias. 

The  above  facts  have  led  some  geologists  to  the  conclusion  that  over 
India,  Australia,  and  South  Africa,  there  were  glacial  conditions  in  the  course 
of  the  Permian  era  —  a  time  when  Europe  and  America  were  under  luxuriant 
vegetation. 

The  Permian  has  much  extent  also  in  Bohemia  and  Moravia.  On  both  sides  of  the 
Alps  are  red  sandstones  underneath  Triassic  beds,  which  are  referred  to  the  Permian.  In 
France,  its  beds  lie  at  the  base  of  the  Vosges,  whence  they  extend  into  the  Black 
Forest ;  at  Autun,  the  thickness  is  3000';  the  rocks  are,  as  usual  elsewhere,  sandstone, 
marlytes,  and  conglomerates. 

In  the  Indian  peninsula,  according  to  the  report  of  W.  T.  Blanford,  Director  of  the 
Geological  Survey,  the  Damuda  series  in  western  Bengal,  with  its  valuable  coal-beds,  and 
also  the  underlying  Talchir  beds,  —  called  together  the  Lower  Gondwana  series,  —  cor- 
respond to  the  upper  part  of  the  Carboniferous  and  the  Permian,  excepting  the  Panchet 
group  at  the  top,  which  is  Triassic.  The  beds  have  a  thickness  of  6000'  to  11,000', 
and  the  coal-beds  an  aggregate  thickness  of  175'  or  more.  A  6-inch  bed  of  coal  occurs  in 
the  Talchir  group.  The  Coal-measures  of  Karharbari  overlie  the  Talchir  beds.  The 
Dainuda  beds  contain  species  of  Glossopteris  (Glossopteris  Browniana  most  abundant), 
Alethopteris,  Tceniopteris,  Sphenopteris,  Sphenophyllum,  Gangamopteris,  Sagenopteris, 
besides  Pterophyllum  and  other  Cycads,  Voltzia  heterophylla,  Vertebraria,  etc.  The 
Rajmahal  group,  of  the  Upper  Gondwana  series,  is  supposed  from  its  fossil  plants  to 
be  Lower  Jurassic,  Cycads  being  the  prevailing  species,  as  much  so  as  Glossopteris  and 
Vertebraria  are  in  the  Damiidas. 

In  Australia,  the  coal  formation,  with  excellent  coal,  occurs  in  Illawarra,  also  on 
Hunter's  River,  and  elsewhere  ;  and,  from  the  fossil  plants,  the  absence  of  Lepidodendrids 
and  Sigillarids,  and  the  abundance  of  Glossopteris,  with  species  of  Sphenopteris,  Verte- 
braria, etc.  (the  range  of  species  much  resembling  that  of  the  Damiida  beds),  together 
with  the  occurrence,  immediately  below,  of  shales  containing  Carboniferous  Brachiopods, 
Conularise,  etc.,  and  a  heterocercal  Ganoid,  Urosthenes  australis  D.,  the  series  was  referred 
by  the  author  (in  his  Wilkes  Exped.  Geol.  Rep.,  1849)  to  the  "  Upper  Carboniferous  or 
partly  Lower  Permian."  It  is  made  the  equivalent  of  the  Damiida  series  by  Blanford. 
W.  B.  Clarke  mentions  the  occurrence  of  leaves  of  Glossopteris  in  the  Coal-measures, 
having  a  length  of  about  2',  and  of  the  frond  of  a  Sphenopteris,  which  when  entire  must  have 
measured  5'  in  length.  The  Coal-measures  are  about  480'  thick,  and  contain  11  seams  of 
coal.  D.  Stur  has  shown  that  in  Germany  and  Austria  the  Permian  is  characterized  by 
related  species  of  Tceniopteris,  Pterophyllum  and  Sagenopteris,  closely  representing  those 
of  India  and  Australia. 

The  Lower  coal-beds  occur  in  Australia  also,  below  the  above-mentioned  beds,  in 
the  Hunter's  River  region,  and  westward  through  Durham,  Brisbane,  etc.,  which 
contain  species  of  Lepidodendron,  Sigillaria,  Knorria,  Cyclopteris,  etc.  Above  the  Upper 
Coal-measures  in  Australia  comes  the  wide-spread  Hawkesbury  sandstone  and  the 


PALEOZOIC   TIME  —  CARBONIC. 

Wianamatta  shale,  with  Palceoniscus  antipodeusTZg.,  but  without  Glossopteris  and  other 
lower  species ;  the  beds  are  probably  Triassic  and  Jurassic.  Jurassic  Ganoids  of  the 
genera  Coccolepis,  Leptolepis,  and  others,  have  been  reported  by  A.  Smith  Woodward 
(1890),  from  specimens  discovered  by  C.  S.  Wilkinson  and  R.  Etheridge,  Jr.  Both  the 
Glossopteris  and  Lepidodendron  floras  occur  in  Victoria,  and  the  former  in  Queensland. 

South  Africa  has  a  coast  border  of  gneiss  and  other  schists,  and  inside  of  it  a  belt  of 
Paleozoic  rocks  with  Carboniferous  at  top  (in  Table  Mountain,  etc.).  The  great  interior 
region  thus  bordered  is  occupied  by  the  "  Karoo  formation"  from  Table  Mountain  north- 
ward over  Orange  Free  State  and  Basutoland,  reaching  the  coast  only  to  the  southeast 
in  Caffraria.  It  includes  (1)  the  Ecca  beds  (with  the  Dwyka  bowlder  bed  [glacial  ?]  in 
the  lower  part),  which  contain  Glossopteris,  etc.,  and  are  regarded  as  Permian,  or  of  the 
age  of  the  Talchir  and  Damiida  beds  of  India ;  (2)  the  Middle  Karoo,  or  Beaufort  beds, 
Permian  or  Triassic ;  and  (3)  the  Upper  Karoo  or  Stormberg  beds,  supposed  to  be  Tri- 
assic. For  a  colored  geological  map  by  A.  Schenk,  see  Peterm.  Mittheil.,  1888. 


LIFE  OF  THE   SUBCARBONIFEROUS   AND  CARBONIFEROUS  PERIODS. 

PLANTS.  —  The  same  genera  of  plants,  with  few  exceptions,  are  repre- 
sented among  the  European  coal-beds  as  occur  in  America ;  and  about  a  third 
of  the  American  species  are  found  also  in  Europe.  In  this  respect  the 
vegetable  and  animal  kingdoms  are  in  strong  contrast;  for  the  species  of 
animals  common  to  the  two  continents  have  always  been  few. 

The  number  of  species  in  the  European  flora  of  the  Carboniferous  (the  British 
included)  is  stated  to  be  nearly  1400,  while  North  America,  so  far  as  described,  including 
the  Carboniferous  and  Subcarboniferous  periods,  has  afforded,  as  enumerated  by  Les- 
quereux  in  the  concluding  part  of  his  Pennsylvania  Report  of  1884,  excluding  fruits,  about 
625  species,  and  including  fruits,  nearly  800.  Over  200  species  of  the  625  exist  also  in 
Europe.  The  number  of  species  of  the  several  genera  common  to  the  two  continents  is 
given  by  Lesquereux  as  follows  :  — 

Calamites,  11 ;  Aster ophyllites,  6  ;  Annularia,  6  ;  Sphenophyllum,  8  ;  Macrostachya,  1 ; 
Neuropteris,  17;  Odontopteris,  5;  Dictyopteris,  3;  Callipteridium,  3;  Alethopteris,  6; 
Pseudopecopteris,  16;  Pecopteris,  29;  Oligocarpia,  1  (O.  GutUeri)  ;  Sphenopteris,  20  ; 
Eremopteris,  2  ;  Ehacophyllum,  7  ;  Stemmatopteris,  1  ;  Caulopteris,  I  ;  Megaphyton,  1 ; 
Lepidodendron,  14 ;  Ulodendron,  4  ;  Knorria,  3  ;  Halonia,  3 ;  Cyclostigma,  I  ;  Lepido- 
phloios,  3 ;  Lepidophyllum,  1 ;  Sigillaria,  25 ;  Syringodendron,  3 ;  Stigmaria,  1 ; 
Cordaites,  1. 

The  flora  of  the  Subcarboniferous  of  Europe  includes  species  of  Archceopteris, 
Sphenopteris,  Lepidodendron  (as  L.  Veltheimanum,  L.  squamosum}-,  Knorria  (K.  imbri- 
cata,  K.  acicularis) ;  Bornia  transitions,  Asterophyllites  elegans,  Stigmaria  ficoides.  The 
flora  of  the  Middle  and  Lower  coal  is  much  like  the  American.  The  Upper  coal  contains 
Sigillarise,  but  rarely  a  Lepidodendron  ;  species  of  Calamites,  Calamodendron,  and  Annu- 
laria are  common,  the  Annularia  becoming  rare  above  ;  species  also  of  Pecopteris,  Callip- 
teris,  Neuropteris,  and  Odontopteris,  are  common,  but  not  of  Sphenopteris.  Cordaites 
also  is  common.  With  these  occur  species  of  true  Cycads,  and  of  Walchia  (  W.  piniformis), 
a  Conifer. 

Among  the  Diatoms  observed  by  Castracani  in  the  coal  of  England,  the  following  8 
species  are  now  living:  Fragillaria  Harrisoni  Sm.,  Epithemia  gibba  Ehr.,  Sphenella 
glacialis  Ktz. ,  Gomphonema  capitatum  Ehr. ,  Nitschea  curvula  Ktz.,  Cymbella  Scotica  Tm.f 
Synedra  vitrea  Ktz.,  Diatoma  vulgare  Bpry. 


700' 


HISTORICAL   GEOLOGY. 


ANIMALS. — Khizopods  are  of  many  kinds.  Fusulina  cylindrica  (Fig. 
1069)  occurs  in  the  beds  from  the  Subcarboniferous  to  the  Permian  in 
Europe  and  Asia;  and  F.  Japonica  is  a  species  from  Japan  described  by 
Gumbel.  The  Subcarboniferous  limestone  in  northern  England  contains 
abundantly  the  arenaceous  form,  Saccammina  Carteri  Brady,  occurring  as 
groups  of  single  isolated  spheroids,  or  occasionally  of  strings  of  them,  averag- 


1127-1132. 


1129. 


1128. 


1127. 


1133. 


BBAOHIOPODS.  —  Fig.  1127,  Orthothetes  (Streptorhynchus)  crenistria;  1128,  Athyris  lamellosa;  1129,  Tere- 
bratula  (Dielasma)  hastata ;  1130,  Productus  longispinus ;  1181,  Spirifer  glaber ;  1132,  Nautilus  (Trema- 
todiscus)  Konincki.  Figs.  1127-1130,  de  Koninck ;  1131,  Davidson  ;  1182,  D'Orbigny. 

ing  one  eighth  of  an  inch,  though  rarely  one  fifth  of  an  inch,  and  making  the 
rock  to  look  as  if  oolitic.  It  is  very  abundant  in  the  "four-fathom"  lime- 
stone of  the  English  Subcarboniferous. 

The  Subcarboniferous  limestone,  like  the  American,  is  noted 
for  its  Crinoids  ;  its  many  Brachiopods  of  the  genera  Productus, 
Chonetes,  and  Rhynchonella  ;  its  Corals  of  the  genus  Lithostrotion, 
Cyathophyllum,  Zaphrentis,  of  which  only  the  first  is  found  in  the 
Coal-measures ;  its  many  Gastropods  of  the  genera  Loxonema, 
Plevrotomaria,  Euomphalus,  Murchisonia,  Bellerophon ,  Macro- 
cheilus,   etc. ;    its   many    Goniatites,    Nautili)    Orthocerata,    and 
Discites;  the  limited  variety  of  Trilobites;  for  Ganoids,  Sela- 
semi-  cnians>  and  Amphibians  among  Vertebrates, 
nifera.    De        Some  of  the  common  Subcarboniferous  Brachiopods  are  rep- 

oninck<     resented  in  Figs.  1127  to  1132. 

Trilobites  occur  only  of  the  three  Carboniferous  genera,  Phillipsia, 
Ghriffithides,  and  Brachymetopus.  A  species  of  Phillipsia  is  represented  in 
Fig.  1133,  P.  seminifera  Morr. 


PALEOZOIC   TIME CARBONIC. 


701 


The  Subcarboniferous  beds  of  Great  Britain  have  yielded  16  species,  but 
the  Coal-measures  none. 

The  foreign  Goal-measures  have  afforded  also  Eurypterids;  Limulids,  as 
species  of  Prestwichia,  Fig.  1136,  and  Belinurus;  Crustaceans,  of  the  higher 

tribe  of  Macra- 
rans>    as     Fig. 

1134,  Anthraco- 
palcemon,  Fig. 

1135,  Gampso- 
nyx,  from  Saar- 
bruck ;    Scorpi- 
ons,     one      of 

which,  from  Bohemia,  Cydophthalmus  senior  of  Corda,  is 
shown  in  Fig.  1137 ;  also  Spiders  of  the  genera  Architarbus, 
Anthracomartus,  Geralinura,  etc. ;  Myriapods  of  the  genera 
Euphoberia,  Xylobius,  Acantherpestes,  Archiulus. 

There  were  also  Insects  of  many  kinds.  The  Orthopte- 
roids  included  Cockroaches,  of  the  genera  EtoUattina,  Fig.  1139,  Anthraco- 
Uattina,  Gerablattina,  and  others;  but  few  kinds  compared  with  North 


Anthracopalaemon  Salteri.     Salter. 


1135. 


1135-1139. 


1138. 


1139. 


CRUSTACEAN.  — Fig.  1135,  Gampsonyx  fimbriatus.  LIMULID.  —  Fig.  1136,  Prestwichia  rotundata  (x  |).  SCOB- 
PION.— Fig.  1137,  Cydophthalmus  senior.  INSECTS.  —  Fig.  1138,  Dictyoneura anthracophila ;  1139,  Etoblat- 
tina  primaeva.  Figs.  1135,  1137, 1138,  Brown ;  1136,  Murchison  ;  1139,  Vogt. 

America;  Protophasmids  (or  species  related  to  the  modern  "Leaf-insects" 
and  "Walking-sticks  ")  of  several  genera,  as  Titanophasma  Fayoli  of  Brong- 


702 


HISTORICAL   GEOLOGY. 


niart,  represented  in  Fig.  1140,  only  ^  the  natural  size,  (which  has,  as 
Brongniart  states,  the  wings  of  a  Neuropter  with  many  characteristics  of 
an  Orthopter,)  Dictyoneura  anthracophila,  Fig.  1138 ;  D.  Monyi,  having  wings 
a  foot  long,  Archceoptilus  ingens  Scudder,  of  the  British  Coal-measures,  having 
a  spread  of  wing  of  about  14  inches  ;  also  forerunners  of  the  "  Dragon-flies," 
one  of  them  having  a  spread  of  wing  much  exceeding  two  feet.  Among  the 

1140. 


OKTHOPTEB.  —  Titanophasma  Fayoli  (x  J),  with  the  outline  in  part  of  the  rock.    Brongniart. 

ITeuropteroids,  the  Lithomantis  carbonaria  of  Scotland  was  probably  nearly 
six  inches  in  spread  of  wing.  Moreover,  Beetles,  or  Coleopteroids,  have 
been  reported  from  the  Coal-measures  of  Silesia,  and  Hemipters  from  several 
localities.  There  were  also  the  inferior  wingless  species,  the  Thysanura 
(common  existing  genera  of  which  are  Lepisma  or  Silver-moth,  and  Podura). 
The  gigantic  Titanophasma  Fayoli,  Dictyoneura  Monyi.,  and  the  fore- 
runner of  the  Dragon-flies,  as  well  as  the  small  Thysanurce,  were  from  the 
Coal-measures  of  Commentry,  in  central  France,  a  locality  that  has  afforded 
C.  Brongniart  for  description  a  wonderful  variety  and  number  of  species. 

Eemains  of  Subcarboniferous  Fishes  are  common  in  Europe  and  Britain  ; 
the  British  Islands  alone  have  afforded  150  species.  Among  them  are  Coch- 
liodus  contortus  Ag.,  Fig.  1141 ;  Cladodus  marginatus  Ag. ; 
Ctenacanthus  major,  Fig.  1142,  one  broken  specimen  of 
which  is  141  inches  long.  Another  broken  spine,  de- 
scribed by  Agassiz,  Oracanthus  Milleri,  is  9£  inches  long 
and  3  inches  wide  at  base. 

Fig.  1143  represents  a  restoration  of  the  Pleuracan- 
thus  (=Diplodus  Ag.)  Oaudryi  of  Brongniart,  from  the 
Carboniferous  rocks  of  France  —  a  Shark  having  a  terminal  mouth. 

The  Fishes  of  the  Coal-measures  include  Selachians  also  of  the  genera 
Ctenodus,  Ctenoptychius,  Helodus,  Cladodus,  Orodus,  etc.,  which  are  also 
mostly  Subcarboniferous.  The  most  common  Coal-measure  genera  of  Ganoids 
are  Palceoniscus,  Amblypterus,  Holoptychius,  and  Megalichthys. 


1141. 


Cochliodus  contortus  (x  J). 


PALEOZOIC    TIME  —  CARBON  1C. 


703 


The  Amphibians  have  nearly  the  same  range  of  characters  as  the  American. 
There  are  Loxomma  Allmanni  Hux.,  from  Edinburgh,  the  skull  10  inches 
wide  and  14  inches  long,  and  the  teeth  with  cutting  edges ;  Anthracosaurus 


1142. 


1143. 


Fig.  1142,  part  of  a  spine  of  Ctenacanthus  major  Ag.  ;  1148,  restoration  of  Pleuracanthus  Gaudryi 

Brongniart. 


Russelli  Hux.,  Lanarkshire  ;  Parabatrachus  Colei  Owen,  British  Coal-meas- 
ures ;  Anthracerpeton  crassosteum  Owen,  Glamorganshire  ;  Archegosaurus 
Decheni  Goldfuss,  Saarbruck,  3£  feet  long;  A.  minor  Meyer,  Saarbruck; 
besides  various  snake-like  and  other  species. 

1.  Brachiopods.  —  Some  of  the  characteristic  species,  besides  those  figured,  are  :  Pro- 
ductus  scabnculus  Sow.  ;  Spirifer  speciosus  Br.,  S.  cuspidatus  Sow.,  8.  disjunctus  Sow.  ; 
Chonetes  Dalmanianus  Kon.  ;  Orthis  Michelini  Morr. 

2.  Limulids.  —  Fig.  1136,  Prestwichia  rotundata  Woodw.,  Coalbrook  Dale;  P.  an- 
thrax Woodw.,  Coalbrook  Dale;   Belinurus  trilobitoides  Woodw.,  Ireland,  Coalbrook 
Dale  ;  B.  Eegince  Baily,  Ireland  ;  B.  arcuatus  Baily,  Ireland. 

3.  Crustaceans.  —  Fig.  1135,  Gampsonyx  fimbriatus  Jordan,  a  Schizopod;  1134,  An- 
thracopalcemon   Salteri,   Lanarkshire,   A.  dubius  S.,   Coalbrook  Dale,  A.   Grossarti  S. 
Lanarkshire  ;  the  broad  flattened  thorax  indicates  a  nearer  relation  to  ^Eglea  and  Galathea 
than  to  Palcemon.     Pygocephalus  Couperi  Hux.  ,  a  Schizopod,  Manchester,  England. 

4.  Myriapods.  —  Euphoberia  Brownii  Woodw.,  Glasgow,  E.  anthrax  Woodw.,  Coal- 
brook  Dale,  XyloUus  sigillarice  Dn.  ,  Glasgow  and  Huddersfield. 

6.  Arachnids.  —  Fig.  1137,  Cyclophthalmus  senior  Corda,  Chomle,  Bohemia  ;  Eophry- 
nus  Prestwichii  Buckl.,  Dudley  ;  Geralinura  Bohemica  Kusta  ;  Architarbus  subovalis 
Woodw.,  Lancashire,  very  near  the  Illinois  species  (page  691)  ;  Protolycosa  anthraco- 
phila  K.,  Silesia  ;  Anthracomartus  Volkelianus  Kranch,  Silesia. 


704  HISTORICAL   GEOLOGY 

6.  Insects.  —  Dictyoneura  anthracophila  Goldb.,  from  Saarbruck;  D.  Humboldtiana 
Goldb.,  ib. ;  Polioptenus  elegans  Goldb.,  ib. ;  Etoblattina primceva  Goldb.,  ib.  ;  Gryllacris 
lithanthraca  Goldb.  (Locust),  ib. ;  Corydalis  Brongniarti  Mant.,  Coalbrook  Dale. 

7.  Amphibians.  —  The  Amphibians  included  Apateon  pedestris  H.  v.  Meyer,  Munster- 
appel ;   Urocordylus  Wandesfordii  Hux.,  Kilkenny,  the  tail  with  75  vertebrae ;  Ophiderpeton 
Brownriggii  Hux.,  Kilkenny,  limbless,  snake- like  and  3'  long ;  Dolichosoma  longissimum 
Fritsch,  from  Ireland,  probably  about  3'  long  and  much  like  the  whip-snake ;  species  of 
Dendrophis,  and  of  other  genera. 

The  following  foreign  Coal-measure  Brachiopods  occur  also  in  the  American  beds : 
Athyris  subtilita,  Spirifer  lineatus  Martin,  Productus  longispinus  Sow.,  P.  latissimus 
Sow.,  P.  punctatus  Martin,  P.  scabriculus  Martin,  P.  costatus  Sow.,  Orthothetes 
(Streptorhynchus)  umbraculus  v.  Buch,  Devonian  to  Permian. 

The  Arctic  Spitzbergen  Coal-measure  plants  include  species  of  Lepidodendron,  Stig- 
maria,  Sphenophyllum,  Aster  ophyllites,  Sphenopteris,  Cordaites;  and  the  Subcarboniferous 
of  Bear  Island  (30m.  south),  the  European  species  Calamites  radiatus,  Lepidodendron 
Veltheimanum,  Knorria  imbricata,  K.  acicularis,  Cyclostigma  Kiltorkense,  Palozopteris 
(Archceopteris}  Bcemeriana,  Sphenopteris  Schimperi,  Cardiopteris  frondosa,  C.  polymor- 
pha,  etc.,  made  a  basis  by  Heer  for  his  Ursa  stage,  but  supposed  by  Dawson  to  include 
some  Devonian  species.  The  beds  of  Spitzbergen  contain  the  Permian  species,  Productus 
horridus,  specimens  twice  the  size  of  those  of  the  European  Permian,  P.  Cancrini  Vern., 
P.  LeplayiVeTn.j  Camarophoria  Humbletonensis  Howse,  Strophalosia  lamellosa  Gein. ; 
Carboniferous  species  of  Euomphalus,  Cyathophyllum,  Syringopora,  Chetetes ;  and  the 
Subcarboniferous  includes  a  Cyathophyllum  limestone  in  which  there  are  4  species  of 
Corals,  2  of  Crinoids,  and  Spirifer  incrassatus,  Terebratula  fusiformis,  and  other  Russian 
Brachiopods. 

LIFE  OF  THE  PERMIAN  PERIOD. 

PLANTS.  —  The  Permian  plants  include  no  Lepidodendrids,  a  few  Sigilla- 
rids;  Ferns  of  the  genera  Neuropteris,  Sphenopteris,  Pecopteris,  Alethopteris, 
Tceniopteris,  Sagenopteris,  Glossopteris,  and  others ;  also  Calamites,  Annularia, 
Asterophyllites ;  Cycads  and  Conifers.  The  Conifers  included  species  of 
Dadoxylon,  Pinites,  Ullmannia,  etc.  The  genus  Walchia,  Fig.  1147,  Walchia 
piniformis  Sternberg,  characterized  by  lax  and  short  spreading  leaves,  began 
near  the  close  of  the  Carboniferous  period,  but  is  most  numerous  in  species 
during  the  Permian.  Tree-ferns  of  the  genus  Psaronius  were  common,  as  in 
the  Upper  Coal-measures. 

Fig.  1144  is  the  pinnule  or  branchlet  of  a  frond  of  Neuropteris  Loschii,  a 
species  common  to  the  Permian  and  Coal-measures ;  1145,  showing  the  vena- 
tion. Fig.  1146,  Annularia  carinata  Sternberg ;  in  1146,  only  the  first  joint 
and  its  whorl  are  shown,  of  natural  size ;  in  1146  a,  a  branch  is  shown  (of 
reduced  size),  consisting  of  its  several  joints  and  whorls,  but  the  natural 
termination  is  wanting.  The  figures  are  from  the  work  of  Geinitz  and 
Gutbier  on  the  "  Dyas  "  of  Saxony. 

The  American  Permian  species  that  are  common  to  the  Permian  formation  of  Europe, 
according  to  Fontaine  and  White,  Pennsylvania  Report  (1880),  are,  for  the  several  genera, 
as  follows:  Equisetites  rugosus,  Calamites  Suckovi,  Sphenophyllum  longifolium,  Annularia 
carinata,  A.  longifolia,  A.  sphenophylloides,  A.  radiata,  A.  minuta,  Neuropteris  flexuosa, 
N.  auriculata,  N.  cordata,  Odontopteris  obtnsiloba,  Callipteris  conferta ;  Pecopteris  ar- 


PALEOZOIC   TIME  —  CARBONIC. 


705 


borescens,  P.  Candolleana,  P.  oreopte.ridia,  P.  pennceformis,  P.  latifolia,  P.  Miltoni,  P. 
dentata,  P.  pteroides,  P.  Pluckeneti,  P.  German,  Goniopteris  emarginata,  G.  elegans, 
Alethopteris  gigas  ;  Rhacophyllum  filiciforme,  R.  lactuca,  Sigillaria  Brardii.  In  addition, 
Tceniopteris  Lescuriana  is  near  T.  multinervis,  T.  Newberryiana  near  T.  vittata ;  Cau- 
lopteris  elliptica  is  allied  to  C.  peltigera,  C.  gigantea  to  C.  microdiscus,  and  Baiera 
Virginiana  to  B.  digitata. 

1145.  1144-1147. 


1144 


1147. 


Figs.  1144,  1145,  Neuropteris  Loschii ;  1146, 1146  a,  Annularia  carinata ;  1147,  Walchia  piniformis.    All  Geinitz. 

ANIMALS.  —  Corals  of  the  Cyathophyllum  family,  Brachiopods  of  the 
genera  Productus,  Spirifer,  and  Orthis,  Pteropods  of  the  genus  Conularia, 
Cephalopods  of  the  genus  Orthoceras,  and  Ganoid  fishes  with  vertebrated 
tails,  give  a  Paleozoic  character  to  the  Fauna.  But  there  are  many  new 
tribes :  among  these,  the  most  prominent  is  that  of  Eeptiles. 

This  transition  character  is  apparent  also  in  the  number  of  old  animal 
types  as  well  as  vegetable  that  here  nearly  or  quite  fade  out,  —  for  it  is  the 
period  of  the  last  of  the  species  of  Productus,  Orthis,  Murchisonia;  nearly 
the  last  of  the  extensive  tribe  of  Cyathophylloid  Corals,  which  made  coral 
reefs  of  far  greater  extent  than  those  of  modern  seas ;  nearly  the  last  of  the 
extreme  vertebrate-tailed  (heterocercal)  Ganoids. 

1148. 


Paleeomscus  Freieslebeni  (xj).    Murchison. 

1.  Fishes.  —  Ganoids  occur  of  the  genera  Palceoniscus,  Fig.  1148;  Platyso- 
mus,  Acrolepis,  Pygopterus,  Ccelacanthus ;  genera  that  are  also  Carboniferous. 
The  figure  illustrates  the  heterocercal  feature  of  the  species.     There  were 
also  Cochliodont  and  Petalodont  Sharks. 
DANA'S  MANUAL  —  45 


706 


HISTORICAL  GEOLOGY* 


2.  Amphibians. — A  species  of  Dasyceps,  D.  Bucklandi,  occurs  at  Durham, 
England,  and  others  of  Branchiosaurus,  Hylonomus,  Ophiderpeton,  etc.,  in 
European  beds. 

3.  Reptiles.  —  The  Reptiles  of  the  foreign  Permian,  like  those  of  America, 
are  in  part  Rhynchocephalians.     The  earliest  genus,  Palceohatteria  of  Cred- 
ner  (1888)  is  from  the  Middle  Permian  (Rothliegende)  of  Saxony.     A  skull 
from  one  of  Credner's  figures  is  shown  in  Fig.  1150.     The  palatine  bone  has 


1149. 


1149-1152. 


1161. 

Fi, 


REPTILES.  —Fig.  1149,  Proterosaurus  Speneri;  1150,  Palaeohatteria  longicaudata ;  1151,  ankle  bones  (t,  astraga- 
lus, ft,  calcaneum,  I  to  V,  metatarsals,  with  T,  tibia,  and  Fi,  fibula);  1152,  pelvic  bones  (pu,  pubis ;  il,  ilium  ; 
is,  ischium  ;  with/,  femur).  Fig.  1149,  von  Meyer;  1150-1152,  Credner,  '88. 

teeth,  and  also  the  vomer,  as  common  in  Amphibians.  The  close  relations  to 
the  New  Zealand  Hatteria  are  pointed  out  by  Credner.  The  beak-like  form 
of  the  anterior  part  of  the  head,  to  which  the  name  Rhynchocephalian  refers, 
is  absent  in  this  early  species  of  the  group.  Proterosaurus  (Fig.  1149)  is  a 
related  but  more  lizard-like  form  from  the  Upper  Permian  of  Thuringia. 
With  the  Palseohatteria  occurs  also  (Credner,  1889)  a  related  Reptile,  the 
Cadaliosaurus.  Like  Mesosaurus  (Stereosternum) ,  these  Permian  Reptiles 


PALEOZOIC   TIME  t— CARBONIC.  TOT 

represent  the  most  generalized  type  of  Reptiles,  the  five  tarsal  bones  of  the 
Palaeohatteria  (1  to  5)  with  which  the  five  metatarsals  (i,  n,  in,  iv,  v) 
were  articulated  are  shown  in  Fig.  1151,  in  which  T,  Fi  are  parts  of  the  tibia 
and  fibula. 

Other  Reptiles  are  the  Anomodonts  and  Theromores.  The  former  have 
large  tusks  in  the  jaws,  and  no  other  teeth;  they  include  the  genus  Dicynodon 
of  Owen,  which  has  species  in  the  Permian  Beaufort  beds  of  South  Africa, 
and  also  in  the  overlying  Triassic  beds. 

1.  Echinoderms.  —  Crinoids  near  Cyathocrinus ;  Echinoderms  of  the  genus  Archceo- 
cidaris. 

2.  Molluscoids .    Brachiopods.  —  Spirifer  alatus  Schloth. ,  England,  Lower  Zechstein  in 
Saxony —  some  specimens  2|  inches  broad  ;  Spiriferina  cristata  Dav.,  Zechstein,  Germany; 
Productus  horridus  Sow.,  England,  Germany,  characteristic  particularly  of  the  Lower 
Zechstein,  and  occuring  also  in  the  Kupferschiefer ;  Strophalosia  excavata  Gein.,  England, 
Germany,  S.  Goldfussi,  ibid. ;  the  species  of  the  genera  Productus  and  Strophalosia  are 
exceedingly  abundant  in  individuals;    Camarophoria  Schlotheimi  von  Buch,   Russia, 
Germany,  England ;  C.  superstes,  Russia. 

3.  Mollusks.     (a)  Lamellibranchs.  —  Pseudomonotis  speluncaria  Beyr.,  England,  Rus- 
sia, Germany,  in  the  Lower  Zechstein  ;  Clidophorus  Pallasi  Gein.,  Russia,  Germany ;  My- 
alina  squamosa  Sedg.,  Russia,  England  ;  Avicula  Kazanensis  Vern.,  Russia  ;  Bakewellia 
antiqua  King,  England,  Russia,  Germany  ;  Schizodus  dubius  M.,  common  in  England, 
Germany,  Russia  ;  S.  Schlotheimi  Gein.,  S.  obscurus  Sow.,  and  S.  truncatus  King.    The 
genus  Schizodus  is  of  the  same  family  with  Trigonia,  a  characteristic  genus  in  the  Rep- 
tilian age  ;  it  commenced  in  the  Devonian  and  ends  with  the  Permian. 

(6)  Gastropods  are  rare  fossils  in  the  Permian.  There  are  a  few  species  of  Murchi- 
sonia,  Pleurotomaria,  and  Straparollus,  Paleozoic  genera,  and  of  Dentalium,  Natica, 
Turbo,  etc. 

(c)  Pteropods  occur  of  the  genera  Theca  and  Conularia. 

(d)  Cephalopods  existed,  and  among  them  two  or  three  species  of  Orthoceras  and 
Nautilus. 

4*.  Crustaceans.  —  No  Trilobites  are  known.  Ostracoids  are  common.  Under  Tetra- 
decapods,  the  Amphipod,  Prosoponiscus  problematicus  Schloth.,  Durham,  England.  Under 
Decapods,  besides  Macrurans,  there  is  reported  a  Crab  or  Brachyuran,  from  the  Permian, 
by  von  Schauroth,  who  named  it  Hemitrochiscus  paradoxus.  It  is  |  of  an  inch  long. 
Whether  a  true  Crab  or  not  is  doubtful. 

5.  Vertebrates.  Fishes.  —  Palceoniscus  Freieslebeni  Agassiz  is  common  in  the  Kup- 
ferschiefer, and  is  found  also  in  the  Coal-measures  in  England,  at  Ardwick.  Other  species 
are  :  Palceoniscus  elegans  Sedgw.,  P.  comptus  Ag.,  Platysomus  macrurus  Ag.,  PL  gibbosus 
Bl.,  Acrolepis  Sedgwickii  Ag.,  Pygopterus  mandibularis  Ag.,  Ccelacanthus  granulatus  Ag., 
etc.  Janassa  bituminosa  Miinst.  and  Wodnika  striatula  Mtinst.  are  species  of  Cestraciont 
sharks  from  the  Kupferschiefer. 

The  Paleozoic  character  of  the  life  of  the  Permian,  as  already  shown,  is  strongly 
marked.  Geinitz  observes,  further,  that  the  Terebratula  (Dielasma)  elongata  Schloth.  of 
the  Zechstein  approaches  a  Devonian  form ;  Camarophoria  Schlotheimi  Kg.  (Zechstein)  is 
near  the  Carboniferous  C.  crumena  Mart.  ;  Spirifer  Clannyanus  Dav.  (Zechstein),  near 
the  Carboniferous  S.  Urii  ;  Spiriferina  cristata,  near  the  Carboniferous  S.  octoplicata.  The 
genus  Schizodus  ends  with  the  Permian,  as  well  as  Orthis,  Camarophoria,  Productus,  and 
Strophalosia. 


708  HISTORICAL   GEOLOGY. 


GEOLOGICAL  AND  GEOGRAPHICAL  CHANGES  DURING  THE  PROGRESS  OF  THE 

COAL-MEASURES. 

The  beds  of  the  Coal-measures  vary  in  kind  of  rock  between  shales,  sand- 
stones, conglomerates,  and  limestones,  clay  beds,  iron  ore  beds,  and  coal-beds ; 
and  differ  in  conditions  of  origin,  between  those  of  salt  water,  brackish 
water,  and  fresh  water.  Moreover,  the  beds  bear  evidence  of  the  changes  in 
water  level  that  took  place  during  the  progress  of  the  long  series.  In  the 
various  regions,  the  clayey  beds  beneath  the  coal  evince  that  they  were 
usually  of  marsh  or  fresh-water  origin,  like  the  coal-beds,  by  the  absence  of 
marine  relics,  and  the  presence  of  roots  and  sometimes  of  stumps  of  the 
trees  that  grew  in  the  clay  as  their  soil. 

In  Nova  Scotia,  where  deposits  were  made  during  the  era  to  a  thickness 
of  13,000  feet,  the  beds  of  the  Subcarboniferous  are  partly  marine,  tut  the 
Coal-measures  and  Permian  are  mainly  of  brackish  or  fresh- water  origin ; 
for  only  one  bed  has  been  found  to  contain  marine  fossils.  This  region  was 
a  wide  basin  in  the  Acadian  trough,  at  the  mouth  of  the  St.  Lawrence  Eiver. 
Specimens  of  the  Pupa  or  land-snail,  described  by  Dawson  (page  676),  occur 
in  an  under-clay  more  than  1200  feet  below  the  level  of  the  stump  in  which 
the  species  was  first  discovered ;  and  in  this  interval  there  are  21  coal-seams, 
showing,  as  Dawson  observes,  that  the  species  existed  during  the  growth  and 
burial  of  at  least  21  forests. 

The  oscillations  in  water  level,  indicated  by  the  alternations  in  the 
deposits,  were  slow  in  progress ;  movement  by  the  few  inches  a  century 
accords  best  with  the  facts.  When  under  verdure,  the  surface  must  have 
lain  for  a  long  period  almost  without  motion ;  for  only  a  very  small  change 
of  level  would  have  let  in  salt  water  to  extinguish  the  life  of  the  forests  and 
jungles,  or  have  so  raised  the  land  as  to  dry  up  its  lakes  and  marshes.  Hence 
the  grand  feature  of  the  period  was  its  prolonged  eras  of  quiet,  with  the 
land  little  above  the  sea  limit.  Again,  for  the  making  of  shales  or  sand- 
stones, the  continent  may  have  rested  long  near  the  water's  surface,  just 
swept  by  the  waves  and  currents,  subsiding  with  extreme  slowness,  so  as  to 
make  thick  deposits  without  letting  in  the  sea.  It  may  have  been  long  a 
region  of  barren  marshes,  and,  in  this  condition,  have  received  its  iron-ore 
deposits,  as  now  marshes  become  occupied  by  bog-ores.  It  must  have  been 
long  in  somewhat  deeper  waters,  and  covered  with  a  luxuriance  of  marine 
life,  in  order  to  have  received  its  beds  of  limestone  holding  marine  fossils. 
Again  the  land  slowly  emerged  from  the  waters,  and  the  old  vegetation 
spread  rapidly  across  the  great  plains,  commencing  a  new  era  of  coal-making 
vegetable  debris ;  or  the  escape  was  only  partial,  and  coal-plants  took 
possession  of  one  part,  and  made  limited  coal-deposits,  while  the  sea  still 
held  the  rest  beneath  it.  Uniformity  in  oscillations  of  level,  through  so  great 
an  area,  is  not  probable ;  and  therefore  the  farmer  continuity  of  a  single 
coal-bed  through  the  East  and  West  requires  strong  proof  to  be  admitted. 

Such  alternations  of  verdure  and  rock  depositions  occurred  also  during 


PALEOZOIC   TIME  —  CARBONIC.  709 

the  Subcarboniferous  and  the  epoch  of  the  Millstone  grit ;  and  they  were 
continued  even  after  the  Carboniferous,  during  the  Permian. 

These  submergences,  although  quietly  carried  forward,  played  havoc  with 
the  leaves,  trunks,  and  stumps,  floating  them  away  for  burial  by  the  in-washed 
sediments.  Some  of  the  transported  stumps  may  occasionally  have  had 
aboard  large  stones  which  they  finally  dropped,  thus  putting  an  occasional 
"  bowlder  "  into  the  forming  beds.  The  encroaching  waters  at  times  flowed 
with  great  force  and  plunging  waves,  as  is  shown  not  only  by  the  formation 
of  coarse  gravel  beds  (now  conglomerates),  but  also  by  the  erosion  of  the 
rock  deposits,  and  in  some  cases  of  the  beds  of  vegetable  debris.  In  Ver- 
milion County,  111.,  as  observed  by  F.  H.  Bradley,  a  portion  of  the  Upper 
Coal-measures,  including  shales,  argillaceous  limestones,  and  two  coal-beds, 
were  carried  away  to  a  depth  of  60  feet ;  and,  in  the  depression  thus  made, 
a  sandstone,  which  belongs  at  the  top  of  the  series,  was  laid  down  so  as  to 
fill  and  overlie  it.  Also,  on  the  same  authority,  in  Vermilion  County,  Ind. 
(adjoining  the  county  just  mentioned),  the  Millstone  grit  (here  a  pebbly 
sandstone),  under  the  Coal-measures,  is  cut  off  short  and  followed  horizon- 
tally by  shale  and  limestone ;  as  if  the  grit  stood  as  a  bluff  in  the  waters,  in 
which  the  latter  rocks  were  deposited.  Other  evidences  of  erosion  have  been, 
described  from  these  states,  and  also  from  Ohio,  Kentucky,  and  Missouri, 
The  change  of  level  over  Iowa,  Illinois,  and  Missouri,  which  permitted  the 
Coal-measures  to  spread  northward  beyond  the  limits  of  the  Chester  lime- 
stone, the  last  of  the  Subcarboniferous  beds,  and  even  beyond  the  Kinder- 
hook  beds,  was  of  the  same  nature  with  the  oscillations  above  referred  to. 
No  unconformity  with  the  Subcarboniferous  was  produced  except  that  of 
overlap.  The  little  value,  as  regards  time  divisions  in  geological  history,  of 
unconformity  by  overlap  or  erosion  is  well  illustrated  by  the  facts  here 
stated. 

The  coal-beds  are  thin  compared  with  the  associated  rocks.  But  the  time 
of  their  accumulation,  or  the  length  of  all  the  periods  of  verdure  together, 
may  have  far  exceeded  the  time  occupied  in  the  accumulation  of  sands  and 
limestones.  If  there  were  but  100  feet  of  coal  in  all,  it  would  correspond  to 
more  than  500  feet  in  depth  of  vegetable  debris.  The  sands  and  clays  which 
came  in  after  each  time  of  verdure  put  under  heavy  cover  the  thick  bed  of 
vegetable  debris  which  had  accumulated,  and  thus  the  decomposition  of  the 
plants  and  the  change  to  coal  took  place,  under  the  best  of  conditions  for 
coal-making.  In  some  regions  the  coal-plants  may  have  been  drifted  to 
their  places  of  deposit ;  but  this  was  not  the  usual  way  in  North  America. 

The  great  marsh  from  which  proceeded  the  Pittsburg  coal-bed  of  the 
Upper  Productive  Measures,  according  to  J.  J.  Stevenson,  was  the  "parent 
marsh  "  also  of  the  coal-beds  above  it  in  the  series,  times  of  temporary  burial 
being  indicated  by  the  intervening  beds  of  shale  and  sandstone  during  the 
progress  of  a  very  slow  and  intermittent  subsidence. 

A  coal-bed  itself  bears  evidence  of  alternations  of  condition  in  its  own 
lamination,  and  even  in  the  alternations  in  its  shades  of  color.  A  layer  one 


710  HISTOBIGAL  GEOLOGY. 

eighth  of  an  inch  thick  corresponds  to  an  inch,  at  least,  of  the  accumulating 
vegetable  remains ;  and  hence  the  regularity  and  delicacy  of  the  structure 
are  not  surprising.  Alternations  are  a  consequence  of  (1)  the  periodicity  in. 
the  growth  of  plants  and  the  shedding  of  leaves ;  (2)  the  periodicity  of  the 
seasons,  the  alternations  of  the  season  of  floods  with  the  season  of  low 
waters  or  comparative  dryness ;  (3)  the  occurrence,  at  intervals  of  several 
years,  of  excessive  floods.  Floods  may  bring  in  more  or  less  detritus,  besides 
influencing  the  fall  and  distribution  of  the  vegetation.  There  may  have  been 
great  variations  in  the  length  of  time  before  the  peat-like  vegetation  after 
its  formation  was  put  under  the  pressure  of  beds  of  clay  or  sand;  and  the 
precise  quality  of  the  coal  would  be  varied  thereby,  the  decomposition  of  the 
vegetation  depending  on  the  amount  of  water,  the  composition  of  that  water, 
and  the  length  of  time  exposed. 

In  some  parts  of  the  marshes  there  were  pools  or  lakes  where  the  vege- 
tation was  long  steeping  and  so  becoming  reduced  to  a  pulp,  to  the  oblitera- 
tion of  all  bedding;  and  in  such  places,  according  to  Newberry,  cannel  coal 
was  often  formed ;  for  it  usually  constitutes  locally  the  lower  parts  of  a  coal- 
bed,  though  sometimes  making  the  whole  thickness.  And,  as  such  ponds  or 
lakes  were  likely  to  have  their  living  species,  so  a  bed  of  cannel  coal  often 
contains  remains  of  fossil  Fishes,  Eurypterids,  Crustaceans,  and  other  species. 
The  Eurypterus  in  its  bed  of  Ferns  figured  on  page  677  was  obtained  from  a 
locality  of  cannel  coal. 

In  conclusion,  the  Coal  period  was  a  time  of  unceasing  change,  —  eras  of 
verdure  alternating  with  others  of  wide-spread  waters,  destructive  of  all  the 
vegetation  and  of  other  terrestrial  life  except  that  which  covered  regions 
beyond  the  Coal-measure  limits.  Yet  it  was  an  era  in  which  the  changes 
went  forward  for  the  most  part  with  such  extreme  slowness,  and  with  such 
prevailing  quiet,  that,  if  man  had  been  living  then,  he  would  not  have  sus- 
pected their  progress. 

In  Europe  the  conditions  were  similar,  in  the  main,  to  those  of  America. 
The  succession  of  Carboniferous  rocks  and  coal  in  the  British  Isles  exceeds 
much  in  thickness  that  in  any  part  of  Europe,  very  much  as  that  of  Nova 
Scotia  exceeds  that  of  Pennsylvania  and  the  states  west.  The  greater  thick- 
ness of  the  formations  (if  not  of  the  coal-beds),  supposing  the  peat-making 
conditions  to  exist,  has  probably  depended  in  each  region  on  the  extent  of 
the  slowly  progressing  subsidence  or  geosyncline.  The  longer  continued  and 
deeper  subsidence  in  Nova  Scotia  favored  greater  thickness  than  in  Pennsyl- 
vania; and  the  amount  of  subsidence  in  Pennsylvania  determined  greater 
thickness  in  that  state  than  in  Illinois.  So  it  was  also  in  the  British  Isles 
as  compared  with  Europe.  Far  west  of  the  Mississippi  in  North  America 
the  general  submergence  of  the  surface  put  a  Carboniferous  limestone  over 
the  region  instead  of  profitable  Coal-measures ;  and  far  east  in  Europe,  Russia 
has  her  barren  coal-strata  of  vast  extent,  on  both  sides  of  the  Urals. 

For  the  making  of  extensive  Coal-measures  a  nice  balancing  of  the  land 
surface  between  submergences  and  emergences  was  a  requisite.  With  a  very 


PALEOZOIC   TIME  —  CARBONIC.  711 

little  too  much  emergence,  even  if  only  a  few  hundred  feet,  there  would 
have  been  no  marshes  in  North  America ;  for  the  land  would  have  been 
drained.  And  with  a  little  too  much  submergence,  limestones  or  barren 
sediments  of  sand  or  gravel  would  have  covered  the  region.  North  America 
was  admirably  arranged  and  poised  for  the  grand  result.  South  America 
probably  lay  a  little  too  low,  and  vast  plains,  although  situated  just  like 
those  of  North  America,  were  left  barren.  Europe  was  not  so  well  off  as 
North  America,  because  of  the  less  extent  of  the  level  land  surface,  and 
the  consequently  less  equable  system  of  oscillations.  Moreover,  the  lands  of 
North  America  were  on  the  wet  border  of  the  Atlantic,  the  western;  and 
those  of  Europe,  as  at  the  present  time,  on  the  dry  border,  the  two  differ- 
ing now  a  fourth  in  amount  of  precipitation. 


METEOROLOGICAL  CONDITIONS  OF  THE  CARBONIC  ERA. 

1.  Temperature  of  the  air  and  waters.  —  Using  the  facts  from  the  rela- 
tions of  existing  plants  to  climate,  —  that  Perns  and  Lycopods  thrive  best  in 
tropical  and  temperate  latitudes,  and  Equiseta  in  temperate,  —  it  is  inferred 
from  the  occurrence  of  coal-plants  of  each  of  these  groups  in  all  latitudes  to 
the  Arctic  regions  that  the  climate  of  the  globe  in  the  Carbonic  era  was  no- 
where colder  than  the  modern  temperate  zone,  or  below  a  mean  temperature 
of  60°  F.     Similarly,  the  occurrence  in  Spitzbergen  of  Corals  of  the  genera 
Lithostrotion,  Cyathophyllum,  and  Syringopora,  and  of  some  species  of  Brach- 
iopods  of  twice  the  size  they  have  in  Europe,  seems  to  show  that  the  waters 
of  the  ocean  were  equally  temperate  throughout.     As  to  excessive  heat  in  the 
tropics,  we  have  no  evidence,  since  the  common  Carboniferous  Brachiopods, 
Productus  semireticulatus,  P.  longispinus,  Athyris  subtilita,  and  a  Bellerophon 
near  B.  Urii  are  found  in  the  Bolivian  Andes. 

2.  Hygrometric  conditions.  —  With  the  atmosphere  so  genial  and  the  ocean 
so  warm,  evaporation  would  have  been  excessive,  rains  abundant,  and  mists 
almost  perpetual.     Over  the  land  on  the  favored  side  of  the  ocean,  from  the 
tropics  to  the  higher  temperate  latitudes,  atmospheric  moisture  would  have 
reached  its  maximum.     The  great  tropical  Atlantic  current  —  a  part  of  the 
world's  machinery  from  the  beginning  of   oceans  and  continents  —  would 
have  given  moisture  freely  to  the  British  Isles,  more  so  than  to  Europe,  and 
more  to  Spitzbergen  than  to  Greenland  and  the  western  Arctic  lands.     More- 
over, Lycopods,  Equiseta  and  most  Ferns  like  shady  as  well  as  moist  places. 

3.  Influence  of  the  carbonic  acid  and  moisture  of  the  atmosphere.  —  If  the 
amount  of  carbonic  acid  used  up  in  the  making  of  Subcarboniferous  and  later 
limestones,  and  of  coal   and  other   carbonaceous   products   stored   in  the 
rocks  of  the  Carbonic  era,  could  be  ascertained,  the  amount  of  carbonic  acid 
abstracted  from  the  atmosphere  by  the  rock-making  and  coal-making  of  the 
era  would  be  known.     In  view  of  the  facts  it  is  safe  to  say  that  the  amount 
of  carbonic  acid  in  the  atmosphere  at  the  beginning  of  the  era  was  at  the 
least  3  in  1000  parts  instead  of  3  in  10,000,  as  it  is  now^    (See  page  485.) 


712  HISTORICAL  GEOLOGY. 

The  presence  of  this  large  percentage  of  carbonic  acid  and  moisture  would 
have  given  the  atmosphere  a  correspondingly  greater  power  of  absorbing 
non-luminous  heat,  or  that  radiated  by  the  warmed  earth,  and  it  therefore 
accounts  for  the  uniformity  in  the  earth's  climate. 

With  conditions  in  the  climate  and  atmosphere  so  favorable,  the  plants 
would  have  been  rapid  in  growth,  in  covering  emerged  lands  with  jungles 
and  forests,  and  in  supplying  vegetable  debris  for  the  thickening  peat-beds. 
Although  the  era  was  one  of  more  clouds  than  sunshine,  growth  must  have 
been,  if  possible,  more  exuberant  than  it  is  now  in  tropical  America. 

The  conditions  were  also  favorable  for  decay.  Old  stumps  of  Lepidoden- 
drids  and  Sigillarids,  poor  in  wood,  decayed  within  as  they  stood  in  the 
swamps,  while  the  debris  of  the  growing  vegetation,  or,  in  some  cases,  the 
detritus  borne  by  the  waters,  accumulated  around  them ;  so  that  their  hollow 
interiors  received  sands,  or  leaves,  or  bones,  or  became  the  haunts  of  reptiles, 
as  was  their  chance. 


FORMATION  OP  COAL  FROM  THE  BEDS  OF  VEGETABLE  DEBRIS. 

The  formation  of  coal  out  of  the  beds  of  vegetable  debris  probably  only 
made  a  beginning  while  these  beds  lay  as  open  beds  of  peat.  The  process  is 
carried  forward  imperfectly  in  the  modern  peat-bed,  and  the  best  result  is  a 
poor  coal,  as  it  contains  25  per  cent  or  more  of  oxygen.  The  deposits  of 
clay  or  sand  over  the  peat  accumulations  of  the  Carbonic  era  prevented  the 
atmospheric  oxygen  from  participating  in  the  change,  and  to  this  is  due  the 
better  product.  The  making  of  coal  from  wood  has  been  explained  on  page 
124,  under  Chemical  Geology.  The  resulting  mineral  coal  consists  (1)  chiefly 
of  carbon;  but  (2)  anthracite  contains  usually  2  to  5  per  cent  of  oxygen  and 
hydrogen,  and  the  bituminous  coals  often  12  per  cent  in  weight  of  oxygen 
and  4  to  6  of  hydrogen;  while  brown  coal,  the  bituminous  coal  of  later 
formations  (which  ordinarily  gives  a  brownish-black  powder),  contains  20 
per  cent  or  more  of  oxygen  with  5  or  6  of  hydrogen. 

Mineral  coal,  therefore,  is  not  carbon,  but  a  compound,  or  a  mixture  of 
two  or  more  compounds,  of  carbon,  hydrogen  and  oxygen,  associated  proba- 
bly with  some  free  carbon  in  anthracite,  and  possibly  in  some  or  all  bitumi- 
nous coal.  In  this  view,  coals  are  mainly  oxidized  hydrocarbons,  or  mixtures 
of  them.  They  are  feebly  acted  on  by  ether  or  benzine,  if  at  all,  and  hence 
contain  little  or  no  mineral  oil,  or  only  a  trace  of  any  soluble  hydrocarbon ; 
but,  at  a  high  temperature,  hydrocarbons  (compounds  of  hydrogen  and  car- 
bon) are  given  out,  and  often  very  abundantly,  in  the  form  of  either  mineral 
oil,  tar,  or  gas. 

The  process  of  the  conversion  of  woody  material  into  coal  is  briefly 
described  on  the  page  referred  to.  The  vegetable  material  from  which  coal 
is  made  may  be  (a)  woody  fiber ;  (6)  cellular  tissue  ;  (c)  bark ;  (d)  spores  of 
Lycopods  (Lepidodendrids,  etc.)  ;  (e)  resins  and  associated  substances.  The 
following  is  the  composition  of  (1)  dried  wood  in  the  mass ;  (2)  cork  (the 


PALEOZOIC  TIME  —  CARBONIC.  713 

bark  of  Quercus  suber)  ;  (3)  the  spores  of  Lycopods ;  (4,  5,  6)  the  common 
kinds  of  mineral  coal;  and  (7)  peat  or  vegetable  material,  partly  altered 
to  the  coal-like  condition. 

I.     Woody  ingredients                                                    Carbon  Hydrogen  Oxygen  Nitrogen 

1.  Wood 49-66  6-21  43-03  1-10 

2.  Cork 65-73  8-33  24-44  1-50  =  100 

3.  Lycopod  spores 64-80  8-73  20-29  6-18  =  100 

II.    Coal  products 

4.  Anthracite 95-0  2-5  2-5 

5.  Bituminous  coal 81-2  5-5  12-5  0-8 

6.  Brown  coal 68-7  5-5  25-0  0-8 

7.  Peat 59-5  5-5  33-0  2-0 

The  relations  of  these  woody  materials  and  coals  are  still  better  exhibited 
in  the  following  table,  giving  the  atomic  proportions  of  the  constituents,  car- 
bon being  made  100 ;  the  atomic  equivalents  of  carbon,  hydrogen,  and  oxygen 
being  respectively  12,  1,  16. 

Carbon  Hydrogen  Oxygen 

1.  Wood    '. 100  150  65 

2.  Cork  100  150  30 

3.  Lycopod  spores 100  166  24 

4.  Anthracite    100  33  2 

5.  Bituminous  coal 100  83  12 

6.  Brown  coal 100  96  27 

7.  Peat : 100  112-5  40 

There  was  little  ordinary  bark  in  the  beds  of  vegetable  debris,  since  the 
cortical  part  of  Lycopods,  Ferns,  and  Calamites  is  not  of  this  nature  ;  although 
nearer  coal  in  constitution  than  true  wood,  bark  resists  alteration  longer,  and 
is  less  easily  converted  into  coal.  The  spores  of  Lycopods  often  retain  their 
amber-yellow  color  in  the  coal,  although  undoubtedly  changed  in  constitu- 
tion. Resins,  which  are  still  nearer  coal  in  the  amount  of  carbon,  but  hold 
less  oxygen,  are  found  mostly  as  resins  in  coal,  especially  when  they  are  in 
lumps  or  grains,  but  of  somewhat  altered  composition.  It  is  probable  that, 
in  the  making  of  bituminous  coal,  at  least  three  fifths  of  the  material  of  the 
wood  were  lost ;  and  in  the  making  of  anthracite,  about  three  fourths.  Besides 
this  reduction  to  two  fifths  and  one  fourth  by  decomposition,  there  is  a  reduc- 
tion in  bulk  by  compression ;  which,  if  only  to  one  half,  would  make  the 
whole  reduction  of  bulk  to  one  fifth  and  one  eighth.  On  this  estimate,  it 
would  take  five  feet  in  depth  of  compact  vegetable  debris  to  make  one  foot 
of  bituminous  coal,  and  eight  feet  to  make  one  of  anthracite.  For  a  bed  of 
pure  anthracite  30  feet  thick  (like  that  at  Wilkesbarre),  the  bed  of  vegeta- 
tion should  have  been  at  least  240  feet  thick. 

Anthracite  coal  is  a  result,  according  to  most  writers  on  the  subject,  of 
the  action  of  heat  on  bituminous  coal,  under  pressure,  attending  an  upturn- 
ing of  the  rocks,  the  heat  driving  off  nearly  all  volatile  matters  it  could 
develop,  and  so  leaving  a  coke  (the  anthracite)  behind.  Made  in  this  way, 


714  .(•::  HISTORICAL   GEOLOGY. 

the  reduction,  in  the  case  of  anthracite,  would  be  to  about  one  eighth,  as 
above  estimated.  The  average  amount  of  ash  in  anthracite  ought,  conse- 
quently, to  be  nearly  half  greater  than  in  bituminous  coal. 

The  production  of  the  anthracite  of  eastern  Pennsylvania  was  referred  to 
the  action  of  heat  on  ordinary  bituminous  coal  first  by  H.  D.  Rogers,  on  the 
ground  of  the  upturned  and  flexed  condition  of  the  rocks  in  that  part  of 
the  state.  The  upturning  fades  out  to  the  northwestward,  and  the  Wilkes- 
barre  anthracite  region  is  on  its  outskirts.  The  heat  produced  in  the  rocks 
by  the  upturning  need  not,  for  the  result,  have  been  either  great  or  much 
prolonged ;  moreover,  it  would  have  spread  laterally  from  the  area  of  great- 
est disturbance,  more  or  less  far  into  the  outskirts,  as  is  well  exemplified  in 
various  metamorphic  regions.  The  following  are  other  facts  favoring  this 
origin  of  the  anthracite :  (1)  The  coal  of  the  upturned  and  more  or  less 
metamorphic  Coal-measures  of  Rhode  Island  is  the  hardest  of  anthracite. 
(2)  The  coal  of  the  Carboniferous  Coal-measures  of  western  Pennsylvania, 
and  that  of  the  states  farther  west,  where  the  beds  are  nearly  horizontal,  is, 
throughout,  bituminous  coal  and  not  anthracite.  (3)  Variations  in  the  con- 
ditions of  the  coal-making  areas  over  the  globe  have  led  to  various  kinds 
of  coal  without  making  anthracite.  Brown  coal,  or  that  containing  a  large 
percentage  of  oxygen,  is  known  to  form  where  there  is  much  access  of  air ; 
and  cannel  coal,  a  kind  rich  in  oil-producing  hydrocarbons,  and  little  oxygen, 
under  conditions  of  prolonged  steeping  beneath  a  deep  covering  of  sediments  ; 
for  all  the  characters  of  the  beds  associated  with  cannel  coal  indicate,  as 
Newberry  held,  the  fact  of  such  a  steeping  of  the  bed  of  vegetable  debris. 
These  are  the  extreme  results,  except  that  more  remarkable  extreme,  the 
loss  of  all  the  oxygen  through  union  with  carbon,  and  thereby  the  making  of 
hydrocarbon  oil  or  gas  as  the  substitute  for  coal.  Anthracite  is  not  known 
among  the  products  so  made,  except  in  regions  of  upturned  rocks,  or  in  the 
vicinity  of  igneous  rocks.  Graphite,  a  grade  beyond  anthracite,  is  formed 
from  the  excessive  heating  of  mineral  coal,  as  is  proved  in  the  metamorphic 
coal  regions  of  Rhode  Island,  Worcester,  and  elsewhere. 


GENERAL  OBSERVATIONS  ON  THE  PALEOZOIC  ERAS. 

GROWTH  OF  THE  AMERICAN  CONTINENT. 

1.  Facts  connected  with  Us  growth.  —  The  facts  which  have  been  presented 
sustain  the  view  that  the  American  continent  throughout  Paleozoic  time  was 
gradually  growing  in  its  rock  formations  and  dry  land,  and  thereby  extend- 
ing from  the  Archaean  nucleus  southeastward  and  southward,  but  not  much 
in  a  southwestward  direction.  It  is  'manifest,  also,  that  after  the  Lower 
Silurian  era  had  passed,  the  growth  took  place  mainly  through  processes  at 
work  over  the  great  Continental  Interior,  —  a  vast  American  Mediterranean 
Sea,  bounded  on  the  north,  northeast,  and  east,  by  Archaean  confines.  More- 
over, the  eastern  areas  of  progress  in  New  England  and  beyond  had  like- 


PALEOZOIC   TIME  —  CAKBONIC. 

wise  Archaean  confines,  even  during  Cambro-Silurian  time,  each  having 
been  an  independent  trough  or  basin.  In  the  Acadian  trough  the  subsidence 
carried  down  the  bottom  of  the  trough  as  deposition  went  forward,  but  not 
the  Archaean  ridges  along  the  confines ;  for  if  these  Archaean  ridges  had  sub- 
sided also,  they  should  have  jiad,  at  the  beginning,  the  extremely  improbable 
height  of  30,000  or  40,000  feet.  The  Acadian  and  the  Gaspe- Worcester 
troughs  were  sinking,  and  receiving,  in  some  parts,  if  not  generally,  formation 
after  formation,  to  the  close  of  the  Carboniferous  period ;  and  the  Connecticut- 
valley  trough,  to  the  middle  or  later  part  of  the  Devonian  era ;  and  this  was 
not  the  last,  as  will  be  shown,  of  the  rock-making  carried  on  in  the  Acadian 
and  Connecticut-valley  troughs.  The  western  part  of  the  Continental  Sea 
had  also  its  areas  of  subsidence  and  deposition.  Only  subsiding  troughs 
received  thick  deposits  for  the  various  formations. 

2.  Diversities  in  kinds  and  in  thickness  of  rocks.  —  The  vast  Continental 
Interior,  shut  away  from  the  more  destructive  forces  of  the  ocean,  afforded 
the  most  favorable  conditions  possible  for  the  growth  of  aquatic  life,  and 
therefore  for  the  making  of  limestones;  and  the  life  had  no  doubt  the 
luxuriance  prevailing  in  the  existing  coral  reef  seas  of  the  tropics. 
What  this  degree  of  luxuriance  is  at  the  present  time  may  be  well 
learned  from  the  admirable  photographs  of  a  volume  by  W.  Saville  Kent  on 
The  Great  Barrier  Reef  of  Australia.  To  see  the  reefs  themselves  is  better ; 
but  this  not  being  readily  attainable,  the  geological  student,  who  would  ap- 
preciate the  profusion  of  life,  and  something  of  the  beauty  of  Paleozoic  reef- 
grounds,  should  see  the  photographs.  The  colors  are  absent,  but  there  is 
everything  else  in  the  pictures.  The  species  represented  are  modern  Corals 
of  various  kinds  and  forms ;  but  it  will  be  easy,  afterward,  to  think  of  vast 
areas  of  Crinoids,  ancient  Corals,  and  other  Paleozoic  productions ;  for  the 
result  is  the  same  in  kind,  if  shell-making  Mollusks  were  the  chief  kind  of 
life.  He  would  learn  also  the  pertinent  fact  that  limestone-making  is  not 
necessarily,  or  ordinarily,  deep-water  work. 

The  effects  of  the  tidal  and  wind-made  currents  in  forming  fragmental 
accumulations  within  the  Interior  Sea,  especially  along  its  borders,  have  been 
variously  illustrated  in  the  preceding  pages,  with  special  reference  to  those 
of  the  northeast  and  east ;  and  there  has  been  brought  out  to  view,  also,  the 
contrast  with  those  of  the  limestone  formations  over  its  interior.  This 
contrast  was  augmented  through  each  of  the  successive  periods  by  the  con- 
trast in  the  amount  of  subsidence  in  progress :  —  over  the  Interior  Sea,  but 
little,  the  formations  only  3000  to  6000  feet  thick ;  over  the  eastern  portion, 
a  great  subsidence,  30,000  to  40,000  feet,  because  included  within  the  area  of 
the  subsiding  Appalachian  trough.  In  the  Continental  Interior,  the  Paleozoic 
rocks  are  full  two  thirds  limestones.  The  coal  formation  there  has  many 
limestone  strata;  the  Subcarboniferous  consists  mostly  of  limestone;  the 
Devonian  and  Upper  Silurian  strata  are  chiefly  limestone ;  the  Lower  Silurian, 
even  through  the  Hudson  period,  mostly  limestone;  and  the  Cambrian 
chiefly  limestone.  The  intercalations  of  strata  of  sandstone  and  shale  indicate 


716  HISTORICAL   GEOLOGY. 

the  varying  locations  and  effects  of  the  marine  currents,  owing  to  varying 
depths  and  changing  outlines  of  the  land.  The  rocks  of  the  northern  border 
of  the  Interior  area  include  much  less  limestone  than  those  of  the  more 
central  portion. 

3.  Maximum  thickness  of  the  rocks  in  North  America.  —  The  maximum 
thickness  of  the  rocks  of  North  America  is  not  known.  The  methods  of 
measurement  of  upturned  rocks  give  so  very  doubtful  results  and  lead 
generally  to  so  large  overstatements,  that  a  trustworthy  estimate  cannot  be 
made.  It  is,  however,  probable  that  the  maximum  thickness  of  the  Cambrian 
is  at  least  20,000  feet,  though  only  so  where  the  rocks  are  mostly  f ragmental ; 
of  the  Lower  Silurian,  18,000  feet ;  of  the  Upper  Silurian,  7000 ;  of  the 
Devonian,  14,000  ;  of  the  Carbonic,  16,000  ;  making  a  total  of  75,000  feet. 

The  relative  maximum  thicknesses  of  the  rocks  have  been  used,  first  by 
S.  Haughton,  as  a  means  of  deducing  the  relative  duration  of  geological  eras 
and  periods.  There  is  great  doubt  over  conclusions  based  on  this  criterion, 
because  thickness  is  dependent  so  generally  on  a  progressing  subsidence  — 
no  subsidence  giving  little  thickness,  however  many  the  millions  of  years  that 
may  pass.  But  as  it  is  the  only  available  method,  it  is  still  used. 

Limestones  increase  with  extreme  slowness,  five  to  ten  feet  of  fragmental 
deposits  accumulating  in  the  time  required  for  one  foot  of  limestone.  This 
general  fact  at  least  is  plain,  that  Eopaleozoic  time,  or  that  of  the  Cambrian 
and  Lower  Silurian  eras,  was  much  longer  than  all  the  rest,  for,  as  shown  on 
pages  509,  520,  it  continued  on  after  the  first  appearance  of  Fishes  and  In- 
sects, types  that  were  formerly  supposed  to  date  from  the  Devonian.  The 
ratio  for  the  Eopaleozoic,  Upper  Silurian,  Devonian,  and  Carbonic  is  perhaps 
7:l:2:2or8:l:2:2. 

BIOLOGICAL  CHANGES  AND  PROGRESS. 

To  appreciate  the  general  system  of  biological  progress,  it  is  necessary  to 
have  some  knowledge  of  the  general  principles  under  which  successions  of 
forms  and  structures  were  produced.  The  following  is  a  brief  review  of  some 
of  the  principles. 

1.  From  the  simple,  regular,  or  primitive  in  structure  to  the  specialized.  — 
Some  of  the  changes  included,  in  cases  generally  of  rising  grade,  are  the  fol- 
lowing: (1)  From  a  structure  in  which  there  are  two  or  more  functions  to 
an  organ,  to  one  in  which  each  function  has  its  special  organ  (an  organ  being 
any  part  of  a  structure  that  is  more  or  less  independent  in  action,  as  even 
a  digit  or  a  tooth).  (2)  From  a  structure  in  which  the  organ  correspond- 
ing to  a  special  function  has  several  uses,  to  one  in  which  special  forms  exist 
in  the  same  structure  for  each  kind  of  use.  (3)  From  simpler  forms  of  spe- 
cialization to  more  complex  forms,  better  adapted  to  the  required  use. 

(4)  From  any  specialized  form  to  others  adapted  to  newly  acquired  uses, 
with  either  accompanying  rise  or  decline   in  general  grade  of   structure. 

(5)  From  structures  in  which  the  head  has  large  sense-organs  and  mouth- 
organs,  to  those  having  all  the  organs  small,  and  the  parts  well  compacted. 


PALEOZOIC   TIME  —  CAKBONIC.  717 

(6)  From  large  aquatic  structures  to  smaller  and  more  concentrated  terres- 
trial structures. 

2.  Approximate  parallelism,  in  many  cases  under  any  tribe,  between  the 
geological  succession  of  structures  and  embryological  succession  in  the  develop- 
ment of  living  organisms.  —  On  this  subject  see  the  remarks  on  page  401. 

3.  Degeneration.  —  (1)  In  cases  where  progress  is  upward,  or  where  there 
is  no  manifest  decline  in  grade:   (a)  Degeneration  of  an  organ  to  a  more 
primitive  form ;   (6)  diminished  size  and  often  complete  disappearance  of  an 
organ  (either  from  disuse,  or  in  consequence  of  accelerated  enlargement  in 
associated  organs).     (2)  In  cases  of  decline  in  grade:  Degeneration  widely 
in  a  structure  through  changes  that  have  the  reverse  order  of  those  enum- 
erated in  the  preceding   paragraphs,  leading  often  through   youth-like  to 
embryonic  forms ;  producing  low-grade  structures  that  are  nearly  normal  in 
form  and  activity ;  also  lower  down,  variously  defective  structures,  sluggish 
in  movement;   and  at  the  extreme  limit  of  degradation  in  Invertebrates, 
structures  that  are  incapable  of  locomotion  after  leaving  the  young  stage ; 
also,  where  an  animal  becomes  aquatic  among  Vertebrates,  producing  struc- 
tures which  retain  activity,  become  urosthenic  and  multiplicate,  and  often 
have  great  length  of  body  and  large  size. 

Degeneration  has  its  limits.  Degenerate  Mammals  are  mammalian  in 
their  more  fundamental  characteristics.  Degenerate  Crustaceans  are  Crus- 
taceans still,  as  they  show  in  their  embryonic  development. 

4.  From  diffuse  structures  to  concentrated.  —  Since  the  brain  or  cephalic 
ganglion,  besides  being  the  source  of  physical  energy,  and  the  chief  seat  of 
sensorial  energy,  is  the  center  of  control  of  all  the  forces  of  the  structures 
except  the  involuntary,  concentration  consists  in  a  shortening  of  the  radius 
of  control,  or  the  distance  through  which  it  has  to  act.     Compare  a  Lobster 
with  the  highest  of  Crustaceans,  a  Crab ;  or  a  Crab  with  its  superior,  an  Ant. 
Some  of  the  cases  included  are  the  following:  (1)  From  a  much   elongate 
structure  —  the  elongation  chiefly  posterior  —  to  an  abbreviated  structure. 
(2)  From  a  multiplicate  structure,  or  one  having  an  excessive  or  indefinite 
number  of  body  segments,  pairs  of  limbs,  articulations  of  limbs,  etc.  —  a  pre- 
vailing feature  of  Articulates  of  the  early  Paleozoic — to  one  consisting  of  a 
normally  limited  number  of  such  parts  and  usually  also  an  arrangement  of 
these  parts  in  two  or  three  groups.     (3)  From  a  structure  having  the  pos- 
terior part  of  the  body  the  chief  locomotive  organ  to  one  having  regular  pairs 
of  limbs  as  the  organs  of  locomotion,  and  having  these  pairs  of  limbs  situated 
anteriorly  in  the  structure ;  in  which  case  the  structure  is  styled  podosthenic 
(from  the  Greek  for  foot  and  strong) .     (4)  From  a  structure  in  which  the 
posterior  pair  of  limbs  in  Vertebrates  is  the  strongest,  and  which  is  there- 
fore merosthenic  (so-named  from  the  Greek  for  thigh  and  strong),  to  one  in 
which  the  anterior  feet  are  the  strongest,  —  a  structure  styled  prosthenic. 


7 18  HISTORICAL  GEOLOGY. 


PLANTS. 

The  line  of  succession  for  Paleozoic  terrestrial  plants  has  been  made 
apparently  clear  by  the  observation  that  the  Rhizocarps,  the  simple  and  small, 
mud-growing  Acrogens,  few  in  existing  species,  of  which  Salvinia  and  Mar- 
silea  are  two  of  the  four  modern  genera,  were  the  probable  source  of  the 
spores  that  so  greatly  abound  in  Devonian  shales  (Dawson).  Through  the 
Protosalvinia,  according  to  this  author,  the  line  leads  up  to  the  Equiseta, 
that  is,  to  the  Calamites  and  Annularice  of  the  earliest  terrestrial  flora. 
Another  simple  type  of  Cryptogam,  related  to  the  former  in  fructification, 
that  of  Selaginella,  which  is  represented  now  by  only  one  single  genus  and 
thus  shows  that  it  is  a  type  of  the  past  now  dwindled,  is  regarded  as  the 
probable  source  of  the  Lepidodendrids,  and  through  them  of  the  Sigillarids, 
or  semi-exogenous  Acrogens,  and  of  the  Yews  and  other  true  Gymnosperms. 

The  special  type  among  these  simpler  Cryptogams  that  was  precursor  to 
the  Ferns  has  not  been  ascertained.  Since  circinate  vernation  characterizes 
both  Cycads  and  Ferns,  and  since  a  genus  of  Cycads,  Stangeria,  now  exists 
in  which  the  foliage  is  Fern-like,  it  is  probable  that  the  line  to  the  Ferns  led 
beyond  to  the  Cycads,  the  other  grand  division  of  the  Gymnosperms,  and, 
therefore,  that  the  Gymnosperms  had  a  double  source. 

In  the  Lepidodendrids,  Sigillarids,  and  related  species,  Cryptogams  reached 
their  culmination,  or  their  greatest  expansion  in  number  of  species,  and  their 
highest  perfection  in  type  of  structure.  The  Lepidodendrids  have  no  species 
in  the  Permian  period,  and  the  Sigillarids  none  after  it.  Further,  the 
Equiseta  passed,  through  the  Calamodendra,  their  time  of  maximum  devel- 
opment during  the  Carboniferous  period.  The  genus  Calamites  had  later 
species,  but  they  were  smaller,  and  the  associated  Equiseta  were  of  the 
inferior  modern  type. 

The  Cycads  culminated  in  later  time ;  and  the  same  is  true  also  of  the 
more  typical  Gymnosperms  —  the  Conifers. 

INVERTEBRATES. 

1.  Hydrozoans ;  Actinozoans.  —  The  Graptolites,  Cambrian  in  their 
beginning  and  Lower  Silurian  in  culmination,  disappear  with  the  Lower 
Devonian.  The  Cyathophylloid  Corals,  or  Tetracoralla,  also  dating  from  the 
Cambrian,  increase  in  number  of  genera  and  species  in  the  Silurian;  with 
other  Corals  make  coral  reefs  in  the  Upper  Silurian ;  are  in  much  greater 
numbers,  and  of  larger  size,  and  make  still  more  extensive  reefs,  but  undergo 
little  increase  in  genera,  in  the  Lower  Devonian;  then  in  the  Lower  Car- 
boniferous they  almost  disappear.  Three  of  the  species  observed  pertain 
to  the  three  older  genera,  Cyathophyllum,  Zaphrentis,  and  Phillipsastrea,' 
and  three  are  new  genera,  Lithostrotion,  Cyathaxonia,  and  Lonsdalia.  The 
recent  discoveries  of  the  "Challenger"  Expedition  report  a  living  species  of 
a  Cyathophylloid  Coral  from  the  bottom  of  the  ocean. 


PALEOZOIC   TIME  ^CARBONIC.  719 

The  Favosites  ended  in  the  Devonian,  but  related  tabulate  Corals  still 
exist. 

2.  Echinoderms.  — Cystoids,  one  of  the  early  Cambrian  types,  the  simplest 
of  the  Crinoid  tribe,  embryo-like  in  their  want  of  symmetry,  are  unknown 
after  the  Devonian.     Crinoids,  also  Cambrian,  multiply  in  genera  and  species 
through  the  Silurian  and  Devonian,  appear  under  a  marvelous  diversity  of 
forms  in  the  Subcarboniferous  period,  and  then  rapidly  decline,  few  appearing 
in  the  Permian,  and  none  of  the  same  paleozoic  type  in  after  time.     The  next 
period,  or  that  commencing  the  Mesozoic,  has  more  modern  forms  under  the 
genus  Encrinus,  closely  related  to  the  living  Pentacrinus. 

Starfishes  commence  in  the  Cambrian,  and  Echinoids,  the  higher  Echino- 
derms, in  the  Silurian.  The  latter  are  abundant  in  the  early  Carboniferous 
era,  but  they  do  not  lose  in  Paleozoic  time  their  low-grade  multiplicate 
characteristic ;  that  is,  the  excessive  number  of  vertical  series  of  plates  in 
the  shell. 

3.  Molluscoids.  —  The  Brachiopods,  earliest  Cambrian  in  origin,  the  most 
abundant  of  all  Paleozoic  animal  life  in  species,  and  in  individuals  under 
species,  had  the  larger  part  of  the  groups,  to  which  they  are  referred,  intro- 
duced in  the  Cambrian  and  Lower  Silurian,  but  were  most  numerous  in 
genera  and  species  in  the  Upper  Silurian  and  Devonian.     And  although  of 
many  species  and  few  genera  in  the  Carboniferous  and  Permian,  the  type 
appears  to  have  lost,  at  the  close  of  the  Permian,  all  the  genera  then  existing 
excepting  four.      These  are:  Lingula,  Crania,  Spirifer,  and  Wiynclionella ; 
all  of  these  continue  into  the  Mesozoic,  showing  remarkable  adaptability 
to  varying  conditions.      Further  study  may  subdivide  the  genera ;  but  the 
general  fact  remains  as  regards  the  groups.     The  early  Cambrian  Orthis  group 
continued  through  Paleozoic  time,  but  appears  to  have  ended  at  its  close. 

4.  Mollusks.  — The  tribe  of  Pteropods  —  if  the  species,  so  referred,  rightly 
belong  here  —  had  predominance  over  other  Mollusks  in  the  Early  and  Middle 
Cambrian,  the  species  being  many  and  large.     They  were  numerous  also  in 
the  Lower  Silurian  ;  but  they  diminish  in  numbers  afterward.     Conulariae  — 
of  much  more  uncertain  relations  — existed  in  the  Upper  Cambrian,  but  had 
their  largest  species  in  the  Silurian,  Devonian,  and  Carboniferous.     They  are 
rare  fossils  afterward ;  the  last  known  is  from  the  Lias. 

Lamellibranchs  and  Gastropods,  commencing  in  very  small  forms  during 
the  Early  Cambrian,  increased  slowly  in  number  of  genera  through  the 
Paleozoic,  without  reaching  a  culminant  condition  in  either  of  their  higher 
divisions.  The  Cephalopods  also  culminate  after  Paleozoic  time.  One  of 
the  early  genera,  Orthoceras,  had  species  of  large  size  through  the  whole 
Paleozoic,  and  survived  until  the  middle  of  the  Mesozoic. 

5.  Limuloids. — Limuloids  of  Eurypterid  type  commenced  in  the  Lower 
Silurian,  have  species  of  great  size  in  the  Upper  Silurian  and  Devonian,  in 
which  era  they  passed  their  culmination,  and  ended  with  small  species  in 
the  Carboniferous  era.     The  family  of  Limulids,  a  branch  from  the  earlier 


720  HISTORICAL   GEOLOGY. 

Limuloids,  appeared  in  the  Silurian.  They  existed  through  the  Carbon- 
iferous era,  and  under  more  compacted  forms  have  been  continued  to  the 
present  time,  four  species  now  representing  the  genus  Limulus,  one  North 
American,  and  three  East  Asiatic  and  East  Indian.  The  Carboniferous 
genera  Belinurus  and  Prestwichia  represent,  under  an  adult  form,  rather 
closely,  the  young  of  the  modern  Limulus ;  and  Cyclus  Packard  considers 
as  representing  a  still  younger  embryonic  stage  of  Limulus. 

6.  Crustaceans. — It  is  stated  on  page  526,  that  Trilobites  had  their  culmi- 
nation in  number  of  genera,  and  in  number,  size,  and  grade  of  species,  in  the 
Lower  Silurian.     They  continued,  with  few  new  genera,  but  under  many  new/ 
species,  in  the  Upper  Silurian,  and  appeared  under  some  extravagant  spiny 
forms  during  the  Devonian ;  but  afterward,  in  the  Carboniferous  era,  the 
species  were  few  and  simple,  only  a  score  being  known.     The  number  of  new 
Carboniferous  genera  yet  found  is  only  two,  and  these  are  closely  related  to 
the  Devonian  Proetus.     Here  the  type  ends. 

No  other  subdivision  of  Crustaceans  appears  to  have  passed  its  culmina- 
tion in  Paleozoic  time  excepting  that  of  the  Ostracoids,  or  the  bivalved 
Crustaceans  (page  525). 

The  Cirriped  or  Barnacle  tribe,  a  degenerate  group,  derived  from  some 
family  of  Ostracoids,  as  remarked  on  page  421,  and  one  of  the  lowest  stages 
of  Crustacean  life,  appeared  as  early  at  least  as  the  Lower  Silurian. 

Other  tribes  of  Crustaceans  continue  to  expand.  True  Isopods  make 
their  appearance  as  early  as  the  Devonian,  and  probably  in  the  successional 
line  of  the  Trilobites.  The  Decapods  are  represented  by  Macrurans  (or 
Shrimps)  in  the  Devonian,  and  by  Brachyurans  (Crabs)  in  the  Carboniferous. 

Trilobites  and  many  of  the  so-called  Phyllopod  Crustaceans  are  examples, 
as  has  already  been  stated,  of  multiplicate  forms,  or  those  having  an  excessive 
number  of  segments  and  members.  The  Early  Cambrian  Protocaris  of 
Walcott  (page  474)  is  a  good  example  of  a  multiplicate,  Apus-like  Phyllo- 
pod, precursor  of  the  true  Decapod  type.  But  normal  numbers  in  segments 
exist  in  some  of  the  "  Phyllopods,"  even  those  of  the  Cambrian,  the  abdominal 
segments  being  reduced  in  number  to  six,  the  normal  number  in  the  Crusta- 
cean type,  and  in  the  same  Phyllopods  the  thorax  also  has  apparently  its 
normal  number  of  body  segments ;  in  which  case  they  are  not  multiplicate, 
unless  in  legs,  and  these  are  not  in  sight  in  the  fossil  specimens.  With 
the  appearance  of  Tetradecapods  and  Decapods  in  the  Devonian,  typical  num- 
bers, as  to  body  segments  and  limbs  —  that  is,  for  all  parts  of  the  structure 
—  have  full  expression;  for  the  Isopods  appear  to  be  (in  view  of  the 
researches  of  Walcott,  Matthew  and  Beecher)  essentially  non-multiplicate 
Trilobites. 

7.  Derivation  of  Limuloids  and  Crustaceans.  —  As  has  been  suggested  by 
Lankester  (and  is  recognized  on  page  423),  it  is  probable  that  all  the  Articu- 
lates are  successional  to  the  Rotifers.     There  is  reason  for  believing,  further, 
that  the  type  of  Annelids,  that  of  Crustaceans,  and  probably  that  of  Limuloids, 
had  their  independent  Rotifer  origin. 


PALEOZOIC   TIME  —  CARBONIC.  721 

The  Nauplius,  or  larval  form,  of  a  Crustacean  shows,  by  its  having  but 
three  pairs  of  limbs  (two  besides  an  antennary  pair),  that  the  type  is  not 
succession al  to  a  many-jointed  Annelid,  but  rather  to  some  type  of  Rotifer. 

The  Eurypterids,  the  early  form  of  the  Limuloids,  are  related  to  Crusta- 
ceans in  the  number  of  body  segments,  it  being  19,  as  in  the  Tetradecapods ; 
and  in  the  fact  that  13  of  these  19  segments  pertain  to  the  thorax  and 
abdomen.  But  the  wide  distinction  exists  that  the  Eurypterids  have  no 
thoracic  or  abdominal  limbs,  and  the  only  true  feet  which  they  have  are  also 
at  base  mouth  organs ;  that  is,  organs  that  pertain  to  the  head.  Moreover, 
as  has  been  shown  to  be  true  in  Lirnulus  by  Packard  and  others,  they  do  not 
pass  through  the  Nauplius  stage  in  their  development.  These  diversities 
and  agreements  appear  to  indicate  a  derivation  for  the  Limuloids  nearly  like 
that  of  the  Crustacean  type,  but  probably  not  from  Crustaceans.  But  since 
Limuloids  cannot  yet  be  proved  to  have  existed  before  the  Trenton  period  in 
the  Lower  Silurian,  a  derivation  from  some  species  related  to  the  Ceratio- 
carids  is  possible. 

Since  many  of  the  Eurypterids  were  fresh-water  or  brackish-water  species, 
the  transfer  to  fresh  water  may  have  been  an  incident  attending  the  diver- 
gence ;  and  also  an  explanation  of  their  attaining  so  great  dimensions,  fresh 
waters  having  been  their  protection.  The  large  Eurypterids,  several  feet  in 
length,  would  have  been  helpless  among  Sharks  and  Ganoids. 

8.  Myriapods,  Arachnids,  Insects.  —  Arachnids  and  Insects  have  their 
Upper  Silurian  species,  but  the  first  of  Myriapods  yet  found  are  from  the 
Lower  Devonian. 

The  remains  of  Insects  in  the  Lower  and  Upper  Silurian,  together  with 
those  of  the  Devonian  and  Carboniferous,  indicate,  according  to  Scudder  and 
Brongniart,  that  Hemipteroid,  Neuropteroid,  and  Orthopteroid  species,  and 
more  or  less  intermediate  forms,  were  then  the  common  kinds.  Nothing 
about  the  earlier  forms  of  Insects  is  known.  The  existence  of  six  pairs  of 
wings  instead  of  four,  that  is,  one  for  each  segment  of  the  thorax,  may  have 
been  a  primitive  feature ;  but  this  is  not  considered  probable.  The  great 
size  of  some  of  the  Devonian  and  Carboniferous  species  is  a  remarkable 
feature  of  the  age.  A  spread  of  wing  exceeding  two  feet  is  a  size  now 
existing  only  in  large  Bats  and  Birds. 

The  Neuropteroids  and  Orthopteroids  were  the  predominant  types;  and 
among  them  were  intermediate  species,  as  has  been  already  illustrated.  The 
latter  type  as  regards  the  family  of  Cockroaches,  as  explained  by  Scudder, 
culminated  before  the  close  of  the  Paleozoic.  Previous  to  its  close,  the  wings 
of  the  two  pairs  in  these  species  were  alike  in  diaphaneity,  very  nearly  alike 
in  size,  and  hence  equally  efficient  as  flying  organs.  But  in  the  following 
period  (as  illustrated  by  specimens  from  Colorado),  the  anterior  pair  begin 
to  show  some  thickening  and  obscuration ;  and  in  the  present  era  nearly  all 
the  species  have  the  anterior  wings  coriaceous,  and  fitted  to  serve,  as  in 
Beetles,  almost  solely  or  solely  as  wing  covers.  The  posterior  wings,  on 
DANA'S  MANUAL  —  46 


722  HISTORICAL   GEOLOGY. 

the  contrary,  have  retained  their  transparency,  neuration,  and  use.  Scudder 
remarks,  further,  that  a  similar  change  took  place  after  the  Paleozoic,  in  the 
Orthopteroids  generally,  though  to  a  less  extreme  degree ;  and  it  appears 
therefore  that  the  Carbonic  era  was  the  time  of  culmination  not  only  for  the 
Cockroach  family,  but  for  the  tribe  as  a  whole.  The  change  was  a  loss  of 
locomotive  function  by  the  anterior  pair  of  wings,  and  an  example  therefore 
of  degeneration ;  and  it  was  attended,  as  Scudder  states,  by  a  great  loss  in 
the  size  of  the  species,  and  especially  of  the  wings ;  the  mean  length  of  the 
anterior  wings  in  the  Paleozoic  species  of  Cockroaches  being  a  little  over  an 
inch  (26  mm.),  and  40  per  cent  less  in  later  kinds.  Among  Hemipteroid 
species,  the  Permian  Eugereon  Bockingi,  of  Germany,  had  the  wings  of  both 
pairs  similarly  diaphanous,  while  in  the  Plithanocoris  of  the  Permian  of 
Missouri,  described  by  Scudder,  the  anterior  pair  were  much  thickened;  the 
result,  probably,  as  in  the  Orthopteroids,  of  degeneration.  It  is  probable 
that  Carboniferous  Beetles  had  a  like  method  of  origin  from  Insects  having 
four  diaphanous  wings ;  but  the  line  of  descent  remains  unknown. 

The  Scorpions  of  the  Upper  Silurian  are  much  like  those  of  modern 
time.  The  type  is  the  lowest  among  the  tribes  of  Arachnids,  notwithstanding 
their  size.  As  in  a  Crustacean  or  Eurypterus,  the  body  (Fig.  799)  obviously 
consists  of  a  cephalothorax  and  a  long  abdomen. 

True  Spiders  have  not  yet  been  found  in  rocks  earlier  than  the  Carbon- 
iferous ;  and  this  is  probably  because  Spiders  are  so  little  likely  to  be  fossil- 
ized ;  for  they  are  not  only  smaller  animals  than  the  Scorpion,  but  also  they 
are  unlike  them  in  not  having  a  durable  exterior. 

9.  Derivation  of  Arachnids.  —  The  line  to  the  lower  and  earlier  Arachnids 
—  that  is,  to  the  Scorpions  —  leads  up,  according  to  Van  Beneden,  Packard, 
and  others,  from  the  early  Pterygotus-like  Limuloids.  The  early  Scorpions, 
as  well  as  the  modern  kinds,  have  the  same  number  of  body  segments  as  a 
Eurypterus  or  Pterygotus :  namely,  seven  thoracic  and  six  abdominal  (pre- 
cisely the  normal  number  in  Crustaceans) ;  the  same  cephalic  relations  of  the 
legs ;  the  same  absence  of  abdominal  appendages ;  a  like  absence  of  thoracic 
appendages  from  all  the  segments  excepting  the  first  two ;  and  similar  func- 
tions in  the  members  pertaining  to  these  two  segments.  Further,  accord- 
ing to  B.  Peach,  these  early  Limuloids  sometimes  have,  like  the  Scorpions, 
pairs  of  "combs"  or  pectinated  organs  on  the  underside  of  some  of  the 
thoracic  segments. 

But  in  this  change  from  an  aquatic  to  a  terrestrial  species  the  upward 
progress  in  structure  was  great.  The  four  posterior  pairs  of  feet  in  the 
terrestrial  Scorpion  have  no  longer  the  low-grade  feature  of  serving  for  jaws 
as  well  as  feet,  but  are  simply  feet ;  they  are  the  chief  organs  of  locomotion, 
and  only  those  of  the  anterior  pair  are  appendages  to  the  mouth.  The 
antennae  are  shortened  to  pincers  (falces)  that  also  serve  the  mouth.  The 
four  pairs  of  feet  are  thus  cephalic  organs,  if  comparison  be  made  with 
the  Limuloids  and  Crustaceans ;  though  in  Arachnology,  they  are  called 


PALEOZOIC   TIME  —  CARBONIC.  723 

thoracic.  Air-breathing  was  another  new  feature ;  and  for  this  purpose  parts 
of  the  body  had  air-vessels  or  tracheae  which  opened  by  breathing  holes,  or 
spiracles,  on  the  under  side  of  four  of  these  "  thoracic  "  segments.  In  the 
later  true  Spiders  the  body  "had  lost  its  Eurypteroid  abdomen,  but  had  still, 
in  Paleozoic  species,  its  distinctly  segmented  thorax ;  and  this  thorax  is  the 
abdomen  of  Arachnology.  (It  is  segmented  in  some  modern  species,  while 
in  others  the  subdivisions  have  become  obsolete  or  are  but  faintly  indicated.) 
The  abdomen  of  the  Eurypterid,  however,  exists  as  a  slender  jointed  thread  in 
Geralinura  of  Scudder,  of  the  Carboniferous,  which  has  its  Illinois  and  also 
Bohemian  species,  and  has  survived  till  now  in  the  modern  Thetyphonus. 

10.  Derivation  of  Myriapods  and  Insects.  —  Myriapods,  although  inferior 
to  Insects,  are  as  yet  known  only  from  the  early  Devonian.  The  Devonian 
species,  and  also  those  of  the  Carboniferous,  are  of  the  Milleped,  or  lower, 
doubly-multiplicate  section  of  Myriapods,  with  one  exception,  that  of  the 
remarkable  few-jointed,  caterpillar-like  Palceocampa  of  Meek  and  Worthen. 

The  fact  of  a  line  of  succession  from  Worms  to  Myriapods  and  from 
Myriapods  to  Insects  has  not  been  proved  by  geological  discovery.  The 
derivation  of  Myriapods  from  some  type  of  Annelids  is  zoologically  suggested, 
as  long  since  recognized,  by  the  apparently  transitional  form  of  Peripatus,  a 
low-grade  Myriapod  resembling  much  the  larve  of  some  Insects,  and  by  the 
like  multiplicate  structure  of  Annelids  and  Myriapods.  It  might  be  inferred 
also  from  the  resemblance  of  the  Palseocampa  of  the  Illinois  Carboniferous 
to  the  caterpillar  of  an  Insect  of  the  genus  Arctia,  as  remarked  by  Scudder. 

Myriapods  are  regarded  as  the  precursors  of  Insects,  on  account  of  their 
approximate  resemblance  to  the  latter  in  antennae  and  the  appendages  of  the 
mouth,  and  because  also  of  the  worm-like  form  of  most  Insect  larves,  these 
larves  appearing  to  be  survivals  of  the  Myriapod  stage.  In  the  change  from 
an  Annelid  and  Myriapod  to  an  Insect,  the  multiplicate  feature  disappeared, 
and  the  number  of  parts  became  essentially  the  fixed  normal  number  of  the 
type,  both  as  regards  the  body  segments  and  their  jointed  appendages. 

The  rise  of  grade  from  the  Myriapod  to  the  Insect  involved  the  appropria- 
tion of  the  three  body  segments  of  the  Myriapod  bearing  the  three  anterior 
pairs  of  feet  (which  correspond  normally  to  half  the  body  segments  of  the 
head  of  an  Isopod  Crustacean)  for  forming  the  isolated  middle  section  of 
the  body  called  the  thorax,  and  the  suppression  of  all  the  other  pairs  of  feet. 
In  both  Spiders  and  Insects,  the  change  involved  also  a  general  concentra- 
tion of  the  structure  toward  the  cephalic  nervous  center;  that  is,  a  shortening 
of  the  range  of  cephalic  control,  and  especially  the  distance  to  the  posterior 
limits  of  locomotive  action. 

While  in  the  Cockroach,  and  related  low-grade  species,  there  is  no  proper 
metamorphosis,  in  higher  Insects,  as  they  rise  in  grade,  the  larval  stage  is 
lower  and  lower  in  embryonic  level,  becoming,  in  the  highest,  destitute  of 
locomotive  organs ;  and  this  fact  suggests  that  the  larval  stage  results  from 
an  attendant  retrograde  embryonic  change  toward,  and  to,  a  line  parallel  with 


724 


HISTORICAL   GEOLOGY. 


the  Myriapod  type,  and  beyond  this,  to  the  memberless  condition  of  the 
Worm.  This  accords  with  a  common  fact  that  the  higher  the  species,  the 
longer  the  stage  of  youth. 

The  relations  in  body  segments  and  limbs  between  the  classes  of  Crusta- 
ceans, Limuloids,  Arachnids,  Myriapods,  and  Insects,  are  shown  in  the 
following  table.  The  segments  of  the  parts  of  the  body  are  numbered  along 
the  left  margin ;  the  zero  opposite  signifies  that  the  segment,  though  present, 
has  no  appendage. 


CRUSTA- 
CEANS 

LIMULOIDS 

ARACHNIDS 

MTRIA- 
PODS 

TKTQPPTS 

Tetradecapods 

Eurypterus 

Pterygotus 

Limulus 

Scorpion 

Phrynus 

Lithobins 

1.  1st  Ant.  1 

0     ] 

Ant. 

Ant. 

Falces  j  •§ 

Falces  1  •§ 

Ant. 

TS 

Ant. 

2.  2dAnt. 

M-P. 

M-P. 

M-P. 

M.     J  M 

M.     j  h§ 

M. 

oS 

M. 

1 

3.  M. 

| 

M-P. 

1 

M-P. 

"i 

M-P. 

rt 

P. 

P. 

M 

MX. 

KM 

Mx.&L. 

w 

4.  MX. 

W 

M-P. 

ffi 

M-P. 

w 

M-P. 

ffi 

P. 

P. 

1 

p     i 

P               }   H 

5.  MX. 

M-P. 

M-P. 

M-P. 

P. 

P. 

i)                    S 

6.  MX. 

M-P. 

M-P. 

M-P. 

P. 

P. 

H 

P. 
P. 

1:    li 

1.  P.           ] 

Fol.  P.  ] 

Fol.  P.  1 

Fol.  P.  1 

0       ' 

J5 

0       ] 

P. 

0 

2.  P. 

Fol.  P. 

Fol.  P. 

Fol.  P. 

Comb 

0 

P. 

0 

3.  P. 
4.  P. 

o 

0 
0 

1 

0 
0 

1 

o 

Fol.  P. 
Fol.  P. 

X 

0 
0 

0 
0 

§ 

P. 
p 

S3 
09 

0 

o 

s 

5.  P. 

& 

0 

H 

0 

Fol.  P. 

J 

H 

0 

0 

1 

P. 

| 

0 

6.  P. 

0 

0 

Fol.  P. 

0 

0 

s 

P. 

S 

0 

2 

7.  P. 

0  J 

0  J 

0  J 

0       - 

0 

P. 

0 

* 

1.  App.       ] 

o  1 

0  ] 

o  ] 

0       ' 

0 

o     J 

P. 

0 

2.  App. 

s 

0 

« 

0 

s 

c 

c 

0 

a 

3.  App. 

Fi 

0 

a 

0 

s 

5 

0 

a 

4.  App. 

c 

0 

,2 

0 

-s 

i 

0 

^j 

P. 

5.  App. 

<- 

0 

<J 

0 

•< 

0 

^ 

6.  App.       J 

o  J 

0  j 

0       > 

^SS-3 

«.l  2-g 
tltf 

In  this  table,  the  following  abbreviations  are  used:  Ant.,  antenna;  App.,  pairs  of 
jointed  appendages,  either  pediform  or  branchial ;  M.,  mandible  ;  MX.,  maxilla ;  P.,  feet ; 
M-P.,  feet  that  serve  also  as  jaws  ;  MX.  &  L.  (under  Insects),  maxillae  and  labium  ;  Fol. 
P.,  foliaceous  or  lamellar  feet  or  appendages. 


Under  the  Limuloids,  the  genus  Eurypterus  fails  of  antennae ;  but  they 
are  present  in  Pterygotus,  and  are  chelate ;  and  this  chelate  (or  thumb-and- 
finger)  form  characterizes  also  the  modern  Limulus,  the  Scorpions,  and  the 
common  Spiders.  In  the  table,  the  two  pairs  of  maxillae  of  Insects  are 
assumed  to  belong  to  a  single  body  segment,  as  held  by  many  zoologists, 
including  (as  he  himself  informs  the  author)  S.  I.  Smith;  the  table  shows 


PALEOZOIC   TIME  —  CARBONIC.  725 

that,  with  this  admission,  the  thorax  and  head  of  an  Insect  are  essentially 
homologous  with  the  head  of  a  Tetradecapod  Crustacean. 

VERTEBRATES. 

1.  Fishes.  —  The  Pteraspid  section  of  the  Placoderms,  having  long  verte- 
brated  tails  fitting  them  to  be  fleet  scullers,  commenced  (according  to  the 
present  state  of  the  facts)  in  the  Lower  Silurian  (page  509).     Cotempo- 
raneously  (the   same   locality  attesting)   there  were  normal  Ganoids,  the 
Crossopterygian,  which  till  recently  were  supposed  to  have  made  their  first 
appearance  in  the  Devonian.     Along  with  these  there  probably  existed  also 
the  Chimseroids,  precursors  of  the  Selachians,  —  a  type  of  primitive  features 
now  almost  extinct. 

The  Devonian  adds  to  these  paleozoic  tribes  the  Brachiate  Placoderms, 
admirably  armor-clad  fishes.  But  they  were  short  in  body,  and  hence  poor 
at  sculling,  but  were  furnished  with  pectoral  limbs  in  the  shape  of  arms  that 
were  seemingly  fitted  for  crawling  and  grubbing  over  muddy  or  sandy 
bottoms  rather  than  for  swimming.  Although  the  appendages  are  called 
"arms,"  and  the  Fishes  were  in  appearance  "brachiate"  (Fig.  982,  page 
624),  the  pectoral  fins  (to  which  they  correspond)  are  homologous  with  the 
hands  in  Vertebrates  and  not  with  the  arms.  They  were  a  poor  equip- 
ment for  either  aquatic  or  terrestrial  service,  and  the  species  end  with  the 
Devonian. 

At  the  same  time  the  Devonian  waters  were  full,  as  has  been  shown,  of 
Selachians,  Dipnoans,  and  typical  Ganoids,  of  great  diversity  in  characters, 
and  many  of  them  unsurpassed  at  any  later  time  in  magnitude. 

Fishes  appear  to  have  reached  their  highest  grade  of  vertebrate  structure, 
and  thus  to  have  culminated  in  the  Dipnoans,  —  species  that  have  not  only 
lungs  for  breathing,  as  well  as  gills,  but  also,  in  the  Ceratodus,  a  genus  dating 
from  the  Carboniferous,  a  finger-like  jointed  midrib  to  the  pectoral  fin 
(Archypterygian),  with  jointed  branches  diverging  from  either  side  of  it. 

No  records  of  the  precursors  of  Placoderms,  Ganoids  and  Sharks  have  yet 
been  found  in  the  rocks.  The  little  Amphioxus,  of  existing  seas  (page  418), 
is  supposed  to  represent  one  of  the  early  forms,  because,  while  having  the 
general  characteristics  of  the  class,  it  is  strikingly  like  an  Invertebrate  in 
part  of  its  embryological  development.  The  Ascidians  are  probably  degen- 
erate forms,  as  held  by  Lankester,  derived  from  some  species  of  still 
lower  grade. 

All  Fishes  are  in  several  ways  eminently  multiplicate  species.  This  is 
seen  in  the  number  of  vertebrae ;  of  articulations  in  the  limbs  when  articula- 
tions exist;  of  teeth,  and  of  tooth-bearing  parts  in  the  mouth. 

2.  Amphibians  and  Reptiles.  —  The  line  from  the  Fishes  to  the  Amphibians 
is  supposed  to  have  been  from  the  Dipnoan  section.     The  resemblance  in 
Amphibians  to  the  Ganoids  generally  is  in  many  respects  close,  it  extending 
even  to  the  form  and  structure  of  their  labyrinthine  teeth ;  and  the  Dipnoans 


726  HISTORICAL   GEOLOGY. 

already  had  the  lung  for  respiration,  which  is  the  characteristic  feature  of 
all  terrestrial  Vertebrates. 

In  rising  from  the  multiplicate  structure  of  the  Fish  to  the  grade  of 
Amphibian,  the  Vertebrate  type  reached  a  fixed  or  normal  limit  in  the 
number  of  limbs,  in  the  number  of  the  bones  of  the  fore  and  hind  limbs, 
including  even  the  number  of  digits,  but  not  in  the  number  of  articulations 
of  the  digits.  In  the  typical  species  of  the  old  Carboniferous  Amphibians 
the  fore  limbs  have  the  scapula,  humerus,  radius  and  ulna,  wrist  bones,  and 
the  five  fingers  characteristic  of  the  higher  Vertebrates. 

Further,  in  rising  to  Amphibians,  the  method  of  progression,  which  is 
urosthenic  in  Fishes,  became  podosthenic  in  the  adult  Amphibian.  The 
young  Amphibian,  or  Tadpole,  retains  the  urosthenic  feature  and  the  gills  of  the 
Fish ;  but  in  passing  to  the  adult  stage,  when  feet  are  developed,  the  higher 
Amphibians  lose  both  the  tail  and  gills  and  have  only  feet  for  locomotion. 
The  tailed  Amphibians  are  intermediate  forms  representing  the  stages  of 
progress.  The  absence  of  limbs  in  the  Amphibian  Snakes  of  the  Carbon- 
iferous is  probably  a  case  of  degeneration. 

True  Reptiles  occur  in  the  Permian.  In  this  higher  grade  of  Vertebrates 
the  fish-like  features  of  gills,  and  of  tails  for  locomotion,  are  absent  in  the 
young  state,  and  feet  are  throughout  the  locomotive  organs.  Besides,  the 
number  of  joints  in  the  digits  of  the  fore  and  hind  feet  of  these  terrestrial 
Vertebrates  has  essentially  the  normal  limit.  But  the  teeth  in  the  earlier 
species  are  still  multiplicate  in  number  and  in  series. 

One  prominent  difference  between  the  Keptilian  and  Amphibian  skeletons 
is  the  existence  in  Amphibians  of  two  occipital  condyles  for  the  articulation 
of  the  skull  with  the  first  cervical  vertebra,  while  in  Reptiles  there  is  but 
one.  In  this  feature  Mammals,  as  early  stated  by  Huxley,  are  more  nearly 
related  to  Amphibians  than  to  Reptiles  or  Birds. 

REALITY  OF  THE  PALEOZOIC  WORLD. 

The  term  Paleozoic  is  not  simply  a  name  for  a  division  of  geological  time. 
It  expresses  a  profound  historical  truth.  It  signifies  the  reality  of  a  Paleo- 
zoic character  in  the  world's  early  life  which  was  exhibited  not  only  in  the 
very  earliest  of  plants  and  animals,  but  also  throughout  the  succession  of 
species,  and  so  decidedly  that  the  Paleozoic  world  stands  out  in  bold  contrast 
with  the  Mesozoic.  This  truth  has  the  greater  importance  inasmuch  as 
Paleozoic  species  were  the  earth's  population  for  more  than  half  of  all  post- 
Archaean  time. 

The  truth  of  this  statement  is  obvious  after  the  review  of  Paleozoic  life 
on  the  preceding  pages.  Corals,  Crinoids,  Trilobites,  Brachiopods  and  Mol- 
lusks,  even  of  their  highest  group,  that  of  Cephalopods,  commence  in  the 
Cambrian  and  are  prominent  through  the  Paleozoic.  Trilobites  end  near  the 
close  of  Paleozoic  time.  The  prolific  Brachiopods  at  its  close  lose  nearly  all 
their  Paleozoic  genera;  Crinoids  drop  their  Paleozoic  characteristics,  and 


PALEOZOIC    TIME  —  CARBONIC.  727 

Corals  also  with  few  exceptions  ;  Nautiloids  lose  nearly  all  their  Orthoceras- 
like  forms ;  while  the  coiled  Nautilus-like  species  culminate  in  the  Carbonif- 
erous, and  have  few  species  and  genera  afterward.  So  the  Insects  had 
Paleozoic  features  which  were  dropped  at  the  same  time,  and  one  division 
passed  its  time  of  culmination.  The  Placoderm,  Dipnoan,  and  Ganoid  Fishes, 
which  were  eminently  Paleozoic  types,  culminated  in  the  Devonian  and  Car- 
bonic eras,  and  only  inferior  Dipnoans  and  Ganoids  existed  later.  Cryptog- 
amous  Plants  culminated  in  the  Carboniferous  era,  and  only  the  Calamites 
and  some  related  genera,  and  a  few  genera  of  Ferns  survived  into  the 
Mesozoic. 

Should  discovery  open  to  view  earlier  species  than  those  now  known  in 
the  Cambrian,  they  would  be  only  earlier  representatives  of  Paleozoic  types, 
or  their  precursor  embryonic  kinds.  And  if  some  of  these  latter  existed  in 
preceding  Archaean  time,  this  fact  would  be  parallel  with  the  appearance  of 
many  Mesozoic  types  in  the  course  of  Paleozoic  time. 

The  disappearance  of  species  at  the  close  of  Paleozoic  time  was  not  due 
chiefly  to  physical  catastrophe,  for  the  Trilobites  had  dwindled  greatly  by 
the  close  of  the  Devonian ;  and  similar  expansions  to  culmination  in  many 
other  tribes,  with  subsequently  a  commencing  decline,  have  been  mentioned 
in  the  preceding  pages,  both  among  plants  and  animals. 

How  far  such  culminations  were  a  consequence  primarily  of  laws  of 
growth  it  is  not  possible  to  say.  There  is  no  doubt  as  to  their  connection 
with  physical  changes  in  progress.  One  of  these  physical  changes  was  the 
slow  removal  of  carbonic  acid  from  the  atmosphere.  The  making  of  shells, 
corals,  and  Crinoid  skeletons,  and  thereby  the  making  of  limestones,  was, 
through  Paleozoic  time,  dependent  mainly  on  carbon  abstracted  from  the 
carbonic  acid  of  the  air  and  waters ;  and  vegetation,  so  far  as  its  products 
became  stored  in  the  rocks,  in  the  form  of  coal,  oil,  gas,  and  other  carbo- 
naceous products,  involved  a  further  abstraction,  as  explained  on  page  485. 
The  purification  of  the  air  which  was  thus  carried  on  was  the  means  of  fitting 
it  for  Spiders,  Insects,  and  other  terrestrial  life,  and  afterwards  for  Am- 
phibians, and  finally  for  Reptiles.  Change  in  animal  as  well  as  vegetable 
types  must  have  been  involved  in  this  using  up  of  the  deleterious  carbonic 
acid.  But  the  extent  of  its  influence  can  only  be  conjectured.  An  examina- 
tion into  the  amount  of  carbonic  acid  which  air  can  contain  without  being 
injurious  to  different  kinds  of  Insects,  and  to  Amphibians,  Reptiles,  and 
other  species,  would  have  much  geological  interest.  Decline  in  the  tempera- 
ture of  the  sea  and  air  through  Paleozoic  time  also  had  its  influence.  But  it 
is  not  safe  at  present  to  attribute  special  facts  to  this  cause. 


SECTION  OP  THE  PALEOZOIC  ROCKS  OF  PENNSYLVANIA. 

The  following  section  of  the  Paleozoic  rocks  of  Pennsylvania,  published  by  H.  D. 
Rogers,  after  the  first  survey  of  the  state,  is  here  added  because  of  its  geological  and 
historical  value. 


728  HISTORICAL   GEOLOGY. 

Lower  Silurian. 

I.   Potsdam.  — "Primal  Series"  of  Rogers:  sandstones  and  slates,  3000'-4000'. 
II.    Calciferous.  —  "  Auroral "  calcareous  sandstone,  250'. 

Chazy.  —  "  Auroral  "  magnesian  limestone,  with  some  cherty  beds,  5400'. 
Trenton.  —  "  Matinal "  limestone,  with  blue  shale,  550'. 

III.  Utica.  —  "  Matinal "  bituminous  shale,  400'. 

Hudson.  — "Matinal"  blue  shale  and  slate,  with  some  thin  gray  calcareous  sand- 
stones, 1200'. 

Upper  Silurian. 

IV.  Oneida.  —  "  Levant  Gray  "  sandstone  and  conglomerate,  700'. 

Medina.  —  "Levant  Red"  sandstone  and  shale,   1050';   and  "Levant  White" 

sandstone,  with  olive  and  green  shales,  760' :  total,  1810'. 

V.    Clinton.  — "  S urgent  Series,"  shales  of  various  colors,  both  argillaceous  and  cal- 
careous, with  some  limestones,  ferruginous  sandstones,  and  iron-ore  beds,  2600'. 
Niagara.  —  Not  well  denned  ;  possibly  corresponds  with  part  of  the  "  Surgent 

Series." 
Salina.  —  "Scalent"  variegated  marls  and  shales,  some  layers   of   argillaceous 

limestone,  1650'. 
VI.   Lower  Helderberg. — "Scalent"  limestone,  thin-bedded,  with  much  chert,  350'; 

"  Pre-meridian  "  encrinal  and  coralline  limestone,  250' :  total,  600'. 
VII.    Oriskany.  —  " Meridian"  calcareous  shales,  and  calcareous  and  argillaceous  sand- 
stone, 520'. 

Devonian. 

VIII.    Upper  Helderberg,  Cauda-galli.  —  "Post-meridian"  silico-calcareous  shales,  200'  to 
300'. 

Corniferous.  —  "  Post- meridian  "  massive  blue  limestone,  80'. 

Marcellus.  —  "  Cadent "  Lower  black  and  ash-colored  slate,  with  some  argilla- 
ceous limestone,  800'. 

Hamilton.  —  "  Cadent"  argillaceous  and  calcareous  shales  and  sandstone,  1100'. 

Genesee.  —  "  Cadent "  Upper  black  calcareous  slate,  700'. 

Portage.  —  "  Vergent"  dark-gray,  flaggy  sandstones,  with  some  blue  shale,  1700'. 

Chemung.  —  "Vergent"   gray,   red,  and  olive  shales,  with  gray  and  red  sand- 
stones, 3200'. 
IX.    Catskill.  —  "  Ponent "  red  sandstone  and  shale,  with  some  conglomerate,  6000'. 

Carboniferous. 
X.  Pocono.  —  "Vespertine"  coarse,  gray  sandstones  and  siliceous  conglomerate  at 

the  eastward,  becoming  fine  sandstones  and  shales  at  the  westward,  2660'. 
XI.   Mauch  Chunk.  —  "Umbral"  fine  red  sandstones  and  shales,  with  some  limestone, 

3000'. 
XII.   Millstone- grit,  or  Pottsville  conglomerate.  — ' '  Serai "  siliceous  conglomerate,  coarse 

sandstone  and  shale,  including  coal-beds,  1100'. 
Coal-measures.  —  2000'-3000'. 


POST-PALEOZOIC  OR  APPALACHIAN  REVOLUTION. 

Paleozoic  time  closed  with  the  making  of  one  of  the  great  mountain 
systems  of  North  America  —  the  Appalachian,  besides  ranges  in  other  lands, 
and  in  producing  one  of  the  most  universal  and  abrupt  disappearances  of 
life  in  geological  history.  So  great  an  event  is  properly  styled  a  revolution. 


PALEOZOIC   TIME  —  CARBONIC.  729 


MOUNTAIN-MAKING  IN   NORTH  AMERICA. 

The  various  steps  in  the  making  of  the  Appalachian  Mountain  Kange, 
or  Synclinorium,  and  the  events  of  the  prolonged  catastrophe,  have  been 
reviewed  at  length  on  pages  353-357.  It  is  there  stated  that  general  quiet 
prevailed  over  the  continent  throughout  the  Paleozoic  eras,  with  the  exception 
of  the  interval  of  Taconic  upturning,  and  those  gentle  oscillations  of  level 
in  the  earth's  crust  that  seem  to  have  been  always  in  progress.  The  extent 
and  steps  of  progress  in  the  geanticline  of  deposition,  which  began  in  the 
early  Cambrian,  has  also  been  explained,  and  particulars  mentioned  as  to  its 
variations  in  eastern  and  western  limits,  as  shown  by  the  limits  of  the  several 
formations ;  and  its  inequalities  in  rate  of  subsidence  over  its  different  parts 
and  in  successive  periods,  as  indicated  (1)  by  the  varying  thickness  of  the 
formations  from  nothing  to  thousands  of  feet,  and  also  (2)  in  the  varying 
kinds  of  rocks  from  shales  to  conglomerates  and  limestones. 

The  review  of  the  facts  relating  to  the  history  of  the  successive  formations 
from  the  Cambrian  onward  has  given  greater  definiteness  and  reality  to  the 
events.  Moreover,  it  has  derived  new  illustrations  of  the  changes  from  the 
remains  which  the  rocks  contain  of  the  life  of  the  world.  The  varying  con- 
ditions of  the  preparatory  geosyncline  during  its  progress  have  thus  become 
strongly  apparent ;  and  they  will  be  much  more  so  when  the  limits  of  the 
successive  formations,  now  so  well  understood  over  New  York,  shall  have 
been  as  thoroughly  investigated  by  the  paleontologist  and  geologist  over 
Pennsylvania,  the  Virginias,  and  beyond. 

The  general  facts  connected  with  the  upturning  of  strata,  30,000  to  40,000 
feet  thick,  which  the  geosyncline  at  the  end  contained,  have  also  been 
reviewed ;  and  an  account  given  of  the  flexures  of  the  beds  in  many  long  lines, 
and  the  general  parallelism  of  the  flexures,  but  with  interruptions  and  over- 
lappings,  and  of  upthrust  faults  of  10,000  feet  and  more.  Mention  has  also 
been  made  of  curves  in  the  course  of  the  finished  mountain  range ;  one  bending 
from  north-by-east  in  the  northern  or  Catskill  portion  to  east-northeast  in 
Pennsylvania,  the  whole  nearly  parallel  with  the  eastern  and  southern  outline 
of  the  nucleal  Archaean  mass ;  the  other,  from  Pennsylvania  to  Alabama  and 
Mississippi,  and  becoming  at  the  south  nearly  parallel  with  the  Mexican  Gulf. 

The  courses  and  character  of  the  flexures  in  the  nearly  east-and-west 
portion  of  the  range  in  Pennsylvania  are  well  shown  on  Lesley's  topographic 
map  of  the  state,  although  greatly  disguised  in  consequence  of  the  denudation 
that  has  taken  place  since  the  time  of  mountain-making.  A  copy  of  the 
map  (Fig.  1153)  is  here  introduced,  exhibiting  the  courses  of  the  multitudes 
of  ridges,  and  their  bends  and  terminations  either  side  of  the  channel  of  the 
Susquehanna  River.  The  map  is  here  reduced  to  too  small  a  scale  to  show 
all  the  minor  flexures,  and  a  diagram  is  added  (Fig.  1154)  giving  in  simple 
lines  the  courses,  positions,  and  bends  of  the  various  ridges  over  the  center  of 
the  state. 


730 


HISTORICAL   GEOLOGY. 


1153. 


PALEOZOIC   TIME  —  CARBONIC. 


731 


On  the  map  on  page  730  the  lines  TS,  1C  are  the  outline  of  the  Triassic  area  of 
Pennsylvania.  The  transversely  lined  areas  on  its  western  part  are  the  oil-producing 
and  gas-producing  areas  of  the  state  ;  the  former  light-lined,  the  latter  dark-lined. 

The  character  of  the  ridges  in  this  east-northeast  portion  of  the  ranges,  as 
they  approach  the  Susquehanna  on  either  side,  their  many  small  zigzag 
flexures  (well  exhibited  in  the  diagram),  and  at  the  same  time  the  wider 
spacing  of  the  ridges  there  than  to  the  westward,  where  the  Appalachian 
Range  takes  its  more  normal  northeasterly  course,  are  points  to  be  noted. 
These  differences  appear  to  have  resulted  in  some  way  from  the  inequality 
of  the  action  of  the  orogenic  lateral  pressure  in  the  two  directions  ;  that  is,  at 
right  angles  to  the  normal  northwesterly  course,  and  to  the  less  normal  north- 
northwesterly.  The  course  of  the  Susquehanna  River  appears  to  have  been 
determined  by  the  warpings  then  occasioned. 


1154. 


-WTc 


Diagram,  showing  the  courses  and  flexures  of  the  ridges  in  central  Pennsylvania.  From  map  by  Lesley. 
Abbreviations:  C,  Chambersburg ;  Ce,  Carlisle;  D,  Danville;  G,  Gettysburg;  H,  Harrisburg ;  Hn, 
Huntington ;  L,  Lewisburg ;  NB,  New  Bloomfield ;  P,  Pottsville  ;  K,  Eeading ;  W,  Williamsport ;  Wk, 
Wilkesbarre ;  Y,  York. 

The  map  also  shows  the  parallelism  between  the  positions  of  the  oil-well 
and  gas-well  areas  in  western  Pennsylvania  and  the  trend  of  the  mountains, 
and  indicates  a  relation  in  their  positions  to  the  mountain  structure,  as  already 
pointed  out.  The  region  of  the  anthracite  is  to  the  eastward,  as  will  be 
seen  on  comparison  with  the  map  on  page  730  ;  while  to  the  west  and  south- 
west there  are  the  great  areas  of  bituminous  coal. 

The  Appalachian  Range  is  a  single  mountain  individual,  or  synclinorium, 
nearly  1000  miles  long.  But  it  is  only  one  of  the  ranges  made  at  this  time 


732  HISTORICAL   GEOLOGY. 

in  eastern  North  America.  There  was  another  to  the  eastward,  the  Aca- 
dian Range,  extending  from  Newfoundland  probably  to  Narraganset  Bay  in 
Rhode  Island,  —  a  distance  exceeding  800  miles,  and  still  another,  that  of  the 
Ouachita  Range  in  Arkansas  (pages  380,  389). 

In  the  Acadian  trough  the  beds  of  Cape  Breton  and  Nova  Scotia  are 
variously  flexed,  and  at  the  southern  end  of  the  trough,  in  Rhode  Island  and 
part  of  Massachusetts  adjoining,  there  are  like  evidences/of  disturbance ;  and, 
moreover,  the  coal  is  changed  to  anthracite,  and  in  some  places  to  graphite. 

Since  the  close  of  the  Lower  Silurian  was  an  epoch  of  upturning  for  the  beds  then  in  the 
northern  part  of  the  Acadian  trough,  it  is  probable  that  it  was  so  for  the  whole  trough, 
including  the  coast  of  Maine  and  the  Cambrian  beds  of  the  Boston  basin.  But  there  is  no 
direct  evidence  as  to  this  or  to  later  times  of  disturbance  along  the  belt  except  in  the  Nova 
Scotia,  New  Brunswick,  and  Maine  regions.  Slates,  grits,  conglomerates,  and  eruptive  rocks 
occur  in  the  Boston  basin  above  the  Cambrian,  without  fossils  or  any  other  evidence  of 
age  ;  and,  as  described  by  Crosby  and  Bouv6,  they  may  be  of  any  period  from  Cambrian 
to  Carboniferous. 

The  three  ranges,  the  Appalachian,  Acadian,  and  Ouachita,  constitute 
together  the  Appalachian  Mountain  System.  The  length  of  the  whole  region 
of  orogenic  disturbance  is  over  2000  miles. 

The  Gaspe- Worcester  trough,  which  contains  some  carbonaceous  beds, 
with  graphite,  at  Worcester,  underwent  post-Carboniferous  upturnings.  But 
details  are  wanting. 

It  is  probable  that  various  dislocations  and  anticlines  over  the  states  north  along  the 
Mississippi  valley  date  from  this  epoch  ;  and  in  Illinois,  several  lines  of  dislocation,  between 
'northwest  and  west-northwest  in  trend,  have  been  described  by  Worthen  (G-eol.  Rep.,  i., 
1866).  (1)  One  crosses  the  Mississippi  in  Alexander  County  at  the  "  Grand  Chain,"  where 
the  Trenton  forms  a  ledge  across  the  river ;  (2)  another  at  Salt  Creek  Point  in  Monroe 
County  ;  (3)  another  below  St.  Louis,  near  the  south  line  of  St.  Clair  County  ;  (4)  another 
at  "  Cap  au  Gres,"  in  Calhoun  County,  "  where  there  is  a  downthrow  of  the  beds  on  the 
south  side  of  at  least  a  thousand  feet,"  and  the  St.  Peters  sandstone  constitutes  the  "Cap 
au  Gres  "  ;  (5)  another,  north-northwest  in  trend,  farther  north,  intersecting  Rock  River, 
Grand  Detour,  and  the  Illinois  River  in  La  Salle  County,  between  La  Salle  and  Utica, 
bringing  the  Lower  Magnesian  limestone  to  the  surface ;  (6)  another,  traceable  from 
Bailey's  Landing  on  the  west  side  of  the  Mississippi  to  Shawneetown  on  the  Ohio.  Of  the 
fifth,  he  states  that  "  it  elevates  the  Coal-measures  300'  to  400',  showing  that  the  disturb- 
ance took  place  at  a  period  subsequent  to  the  deposition  of  the  Coal  formation"  ;  and 
afterward  adds,  with  reference  to  the  whole  series  of  upturnings,  "  It  is  impossible,  with 
the  evidence  before  us  at  this  time,  to  fix  with  certainty  the  relative  dates  of  these  dis- 
turbances ;  but  it  seems  quite  probable  that  none  of  them  date  back  to  a  period  anterior 
to  the  Carboniferous  epoch ;  for  we  find,  in  general,  no  want  of  conformity  between  the 
uplifted  strata  and  any  of  the  superincumbent  Paleozoic  beds." 

There  are  other  lines  of  uplift  or  undulations  farther  north  across  Iowa,  as  described 
by  McGee  (llth  U.  S.  Geol  Surv.,  Annual  Beport,  338,  1891),  which  have  a  trend  of 
N.  30°-40°  W.  The  time  of  origin  is  stated  to  be  doubtful,  except  for  one  anticline,  that 
of  the  Cedar  Valley,  near  Davenport,  Iowa,  which  ' '  does  not  appear  to  affect  the  Coal- 
measures  at  Davenport  and  Rock  Island." 

So  far  as  yet  ascertained  no  great  mountain-making  events  occurred  at 
this  time  over  the  Summit  Region  of  the  Rocky  Mountains.  The  Carbonif- 


PALEOZOIC    TIME  —  CARBONIC.  733 

erous  rocks  appear  to  have  been  followed  by  the  Mesozoic  without  extensive 
intervening  upturnings  in  the  region  of  the  Wasatch  and  through  the  whole 
length  of  the  mountains,  from  western  Texas  and  Mexico  to  the  Arctic  Seas. 

But  west  of  the  Wasatch  belt,  in  the  mountain  ridges  of  the  Great  Basin  to 
the  meridian  of  117^°  W.,  according  to  King,  Carboniferous  limestone  is  to  a 
considerable  extent  the  surface  rock,  there  being  no  overlying  Mesozoic  strata ; 
and  this  limestone  and  the  older  Paleozoic  formations  are  flexed  and  faulted 
in  mountain-making  style.  The  time  of  the  upturning  is  uncertain  because 
of  the  absence  of  later  beds  except  over  the  region  beyond  the  meridian 
of  117^°.  But,  as  King  implies,  it  took  place  probably  at  the  close  of 
the  Paleozoic. 

The  Eureka  Mountains  in  the  Great  Basin  (near  116°  W.  and  39£°  N.),  described  by 
Arnold  Hague  (Geol.  of  the  Eureka  District,  U.  S.  G.  S.  Memoirs,  4to,  vol.  xx.,  1892), 
are  one  of  the  mountain  groups  of  eastern  Nevada,  which  probably  was  upturned  at  this 
time.  The  prominent  ridges,  which  were  produced  largely  by  faults  and  uplifts  (their 
maximum  displacement  13,000') ,  are :  the  Prospect  Ridges,  consisting  of  Cambrian  and 
Silurian  rocks ;  the  Fish  Creek  Mountains,  Silurian  ;  the  Silverado  and  Country  Peak,  Silu- 
rian and  Devonian  ;  Diamond  Mountain,  Devonian  and  Carboniferous  ;  Carbon  Ridge  and 
Spring  Hill,  Carboniferous.  The  thickness  of  the  formations,  as  deduced  from  several  sec- 
tions, according  to  Hague  and  Walcott,  is  as  follows :  Cambrian,  7700' ;  Silurian,  5000' ; 
Devonian,  8000';  Carboniferous,  9300',  —  in  all  30,000'.  This  great  thickness  indicates, 
as  .Hague  suggests,  that  a  profound  geosyncline  north  and  south  in  trend  was  here  made. 
The  Eureka,  Carboniferous,  Devonian,  and  Silurian  beds  have  been  traced  from  the  Eureka 
district  westward  to  that  of  the  Pifion  Range,  which  is  an  indication  that  the  latter  range 
participated  in  the  geosyncline.  How  far  north  the  belt  extends  remains  to  be  ascertained. 
The  Archaean  ridge  of  the  East  Humboldt  Mountains  stands  to  the  east  and  north  of  the 
Eureka  Range. 

The  Eureka  geosyncline  was  wholly  independent  of  that  of  the  Wasatch,  as  shown  by 
the  thicknesses  of  the  several  Paleozoic  formations  occurring  in  the  two ;  for  the  thick- 
ness of  the  Silurian  of  the  Wasatch  is  only  1000',  of  the  Devonian,  2400',  while  that  of  the 
Carboniferous  is  14,000'.  Whether  the  Silurian  unconformability  in  the  Eureka  region 
between  the  Lone  Mountain  limestone  and  the  underlying  quartzyte  is  a  result  of  an 
upturning  at  the  close  of  the  Lower  Silurian,  or  of  later  faulting,  does  not  appear  to  be 
determined  by  the  observed  facts. 


UPTURNINGS  IN  FOREIGN  COUNTRIES. 

Regions  of  upturned  rocks  are  the  only  kind  in  which  there  is  good  reason 
to  look  for  unconformabilities.  Through  the  course  of  Paleozoic  time  in 
Europe,  disturbances  appear  to  have  been  more  frequent  than  in  America. 
But  they  were  inferior  in  extent  to  those  at  its  close.  Murchison  remarks 
that  the  close  of  the  Carboniferous  period  was  specially  marked  by  disturb- 
ances and  upliftings.  He  states  that  it  was  then  "  that  the  coal  strata  and 
their  antecedent  formations  were  very  generally  broken  up,  and  thrown,  by 
grand  upheavals,  into  separate  basins,  which  were  fractured  by  number- 
less powerful  dislocations."  In  the  north  of  England,  as  first  shown  by 
Sedgwick,  and  also  near  Bristol,  and  in  the  southeastern  part  of  the  Coal- 
measures  of  South  Wales,  there  is  distinct  unconformability  between  the 


734  HISTORICAL   GEOLOGY. 

Carboniferous  and  lowest  Permian,  and  this  is  true  also  in  Lancashire  and 
Yorkshire.  The  "Hercynian  system"  of  Bertrand  includes  a  long  range  of 
dislocated  Devonian  and  Carboniferous  rocks  extending  from  Brittany  to 
the  Vosges  and  Ardennes,  and  beyond  along  the  Black  Forest,  the  Harz 
to  Bohemia.  The  line  corresponds  •  nearly  with  the  "  System  of  the 
Rhine"  of  de  Beaumont,  which  was  upturned,  as  he  showed,  before  the 
Triassic  period. 

The  "  great  fault "  in  the  Alps  raising  the  crystalline  schists  in  the  zone 
of  Mont  Blanc,  between  the  Bernese  Alps  on  the  east  and  the  maritime  Alps 
on  the  southwest,  was  made  between  the  Carboniferous  and  Triassic  (or  the 
Lias,  where  the  Trias  is  absent).  The  coal-formation,  which  is  extensively 
distributed  in  the  Swiss  Alps,  is  in  part  semi-crystalline. 

In  Russia,  strata  are  generally  horizontal  or  nearly  so,  and  lie  above  the 
Carboniferous  without  unconformability.  In  the  closing  part  of  Paleozoic 
time,  either  after  the  Carboniferous  or  after  the  Permian,  a  belt  of  rocks 
along  the  Urals  was  folded  and  crystallized ;  for  Carboniferous  rocks  are 
flexed  and  altered  in  the  same  manner  as  in  the  Alleghany  region.  But  the 
backbone  of  the  Urals  is  Archaean. 


NORTH  AMERICAN  GEOGRAPHY  AFTER  THE  REVOLUTION. 

The  various  movements  over  North  America  closing  Paleozoic  time  ended, 
as  announced  on  page  714,  in  making  dry  land  of  the  eastern  half  of  the 
continent.  The  western  coast  within  the  United  States  extended  along  a 
north-and-south  line  near  the  meridian  of  95°  W..  and  farther  north  trended 
northwestward  through  British  America,  as  delineated  on  the  accompanying 
map  (Fig.  1155).  The  dry  land  had  its  Appalachian  Mountain  chain,  and 
was  for  the  most  part  finished  in  its  rock  foundation,  its  mountains,  and  its 
store  of  coal-beds. 

The  positions  of  the  rivers  and  lakes  are  doubtful.  There  were,  beyond  ques- 
tion, a  St.  Lawrence  River  and  other  streams  flowing  off  from  Archaean  lands. 
The  Hudson  River  had  been  a  small  stream  from  the  Adirondack  s,  merely  the 
head  of  the  present  Hudson  River,  emptying  into  the  waters  of  the  eastern 
Continental  Interior  below  Albany.  But  what  course  it  took  after  the  mak- 
ing of  the  Appalachians,  remains  to  be  learned  from  later  records.  The  east- 
ern coast-line  of  the  continent,  south  of  New  York,  which  was  still  outside  of 
the  existing  position  of  the  sea  border,  is  placed  on  the  map  near  that  of  the 
100-fathom  line  —  the  true  margin  of  the  Atlantic  basin.  For  not  only  are 
all  Paleozoic  formations  later  than  the  Lower  Silurian  unknown  on  this  part 
of  the  border,  but  also  all  marine  formations  of  the  Early  and  Middle  Mesozoic. 
This  was  probably  true,  likewise,  of  the  Gulf  border.  Whatever  marine  beds 
were  formed  are  now  deeply  submerged.  The  burial  of  the  shore  region  by 
Cretaceous  and  Tertiary  strata  prevents  direct  observation  except  through 
borings,  and  these  have  not  yet  been  carried  to  a  sufficient  depth  to  decide 
the  question. 


PALEOZOIC    TIME  —  CARBONIC. 


735 


Nearly  all  the  western  half  of  the  continent  was  still  a  sea  of  varying 
depth,  with  perhaps  its  widespread  sand  flats.  Only  one  large  dry-land  addi- 
tion to  the  western  part  of  the  continental  area  is  known  to  have  taken  place ; 
it  occupied,  as  shown  by  King,  a  portion  of  the  Great  Basin,  over  what  is 
now  eastern  and  central  Nevada,  having  the  meridian  of  117|°  W.  near  its 
western  limit.  The  western  semi-continent  was  yet  to  be  supplied  with  thick 
rock-formations  and  with  its  grander  mountains ;  and  veins  of  gold,  silver, 
and  other  metals  were  to  be  formed,  and  coal-beds  to  be  accumulated,  before 
finally  the  emergence  of  "the  Great  West"  from  the  waters  was  completed. 

1155. 


Map  of  North  America  after  the  Appalachian  Revolution. 

Disappearance  of  life.  —  The  disappearance  of  life  at  the  close  of  Pale- 
ozoic time  was  so  general  and  extensive  that  no  Carboniferous  species  is 
known  to  occur  among  the  fossils  of  succeeding  beds,  not  only  in  America 
and  Europe,  but  also  over  the  rest  of  the  world.  The  fact  is  learned  better 
from  Europe  than  from  America;  for  in  Europe  remains  of  marine  life  occur 
in  beds  representing  the  early  part  of  the  following  period,  while  in  America, 
the  first  marine  fossil  known  from  the  Atlantic  border  is  of  the  Cretaceous 
period.  A  large  part  of  the  old  tribes  of  the  sea  and  land  continues  on,  spe- 
cies having  survived  through  the  time  of  catastrophe  ;  and  yet  their  species 
did  not  find  burial  among  later  fossils.  Many  underwent  modifications  and 
appear  later  under  new  forms,  and  thereby  as  new  species.  The  Cycads  and 
Yews  were  among  the  tribes  of  plants  which  were  continued  and  increased 
to  a  later  culmination.  Some  of  the  Corals  of  the  Paleozoic  belong  to  the 


736  HISTORICAL   GEOLOGY. 

group  that  is  represented  among,  and  make,  modern  coral  reefs.  Even  the 
old  straight  Nautiloid,  the  Orthoceras,  had  its  later  species. 

The  Insects  lost,  as  has  been  said,  a  Paleozoic  feature  at  this  time ;  but 
the  tribes  are  still  the  same  as  before  in  their  more  fundamental  characters. 
Pishes,  although  their  period  of  culmination  had  passed,  still  continued  under 
the  tribes  of  Ganoids  and  Dipnoans.  Amphibians  and  Reptiles  held  on,  and 
the  latter  became  the  ruling  life  of  Mesozoic  tin/e.  So  it  was  with  the 
greater  part  of  the  tribes  of  the  Paleozoic.  There  was  no  break  in  the  stream 
of  life,  but  for  the  most  part  only  seeming  interruptions ;  and  many  of  these 
owe  their  prominence  in  geological  history  to  the  culminations  and  declines 
of  types  that  were  in  progress. 

But  it  was  an  epoch  of  relatively  abrupt  change ;  and  if  chiefly  due  to  the 
progressive  evolution  of  new  species,  as  has  been  urged  by  some  geologists, 
there  must  have  been  for  the  result  a  great  acceleration  in  such  changes  in 
consequence  of  the  physical  conditions  produced  by  the  orogenic  disturbance. 
But  the  orogenic  movements  were  local,  and  the  biologically  transforming 
effects  from  such  a  cause  should  have  been  confined  to  the  countries  where 
these  movements  were  in  progress.  The  universality  and  abruptness  of  the 
disappearances  cannot  therefore  be  so  explained.  Very  much  is  left  for  the 
destructive  effects,  direct  and  indirect,  that  is,  the  exterminations  attending 
the  mountain-making. 

The  causes  of  the  exterminations  suggested  by  the  changes  are  two. 
(1)  A  colder  climate  over  the  land,  and  colder  waters  in  the  extra-tropical 
oceans  ;  for  the  emergence  of  the  eastern  semi-continent  of  North  America  and 
of  large  lands  in  the  other  continents  could  not  fail  to  lower  somewhat  the 
temperature  of  the  whole  globe.  With  a  lower  temperature,  the  currents  from 
the  north  sweeping  along  the  coasts  would  have  been  destructive  to  the  marine 
species  living  in  the  waters.  (2)  Earthquake  waves  produced  by  orogenic 
movements.  If  North  America  from  the  west  of  the  Carolinas  to  the  Mis- 
sissippi valley  can  be  shaken  in  consequence  of  a  little  slip  along  a  fracture  in 
times  of  perfect  quiet,  and  ruin  mark  its  movements,  incalculable  violence 
and  great  surgings  of  the  ocean  should  have  occurred  and  been  often  repeated 
during  the  progress  of  flexures,  miles  in  height  and  space,  and  slips  along 
newly  opened  fractures  that  kept  up  their  interrupted  progress  through  thou- 
sands of  feet  of  displacement.  The  Acadian  upturning  took  place  on  the 
ocean's  border ;  and  the  Appalachian  was  not  far  distant  from  it.  Arkansas, 
moreover,  added  to  the  extent  of  the  belt  of  disturbance.  Under  such  circum- 
stances the  devastation  of  the  sea  border  and  the  low-lying  land  of  the  period, 
the  destruction  of  their  animals  and  plants,  would  have  been  a  sure  result. 
The  survivors  within  a  long  distance  of  the  coast-line  would  have  been  few. 
The  same  waves  would  have  swept  over  European  land  and  seas,  and  there 
found  coadjutors  for  new  strife  in  earthquake  waves  of  European  origin. 
These  times  of  catastrophe  may  have  continued  in  America  through  half  of 
the  following  Triassic  period ;  for  fully  two  thirds  of  the  Triassic  period  are 
unrepresented  by  rocks  and  fossils  on  the  Atlantic  border. 


PALEOZOIC    TIME  —  CARBONIC.  737 


TOPOGRAPHIC  CHANGES  IN  THE  INDIAN  OCEAN;  GONDWANA  LAND. 

The  close  relations  in  species  of  India  and  South  Africa  during  the 
Permian  and  Triassic  periods  has  led  to  the  belief  that  the  two  were  then 
connected  by  a  belt  of  land,  and  Suess  has  named  the  emerged  area 
"  Gondwana  Land,"  from  the  name  of  the  series,  including  the  Permian  and 
Triassic  beds,  in  India.  R.  D.  Oldham  remarks  (1894)  that  "the  plants  of 
the  India  and  Africa  Coal-measures  are  absolutely  identical ;  and  among  the 
few  animals  which  have  been  found  in  the  India  deposits,  one  is  indistinguish- 
able from  South  African  species,  and  another  is  closely  allied;  and  both 
faunas  are  characterized  by  the  remarkable  group  of  Reptiles  comprising  the 
Dicynodon  and  other  allied  forms."  In  a  map  by  Neumayr  (1885),  and  its 
reproduction  with  some  modifications  by  Oldham,  the  connecting  belt  of  land 
extends  from  India  south-southwestward  over  the  Indian  Ocean  along  the 
range  of  islands  to  Madagascar  and  southern  Africa.  Among  the  groups  of 
islands  there  is  the  line  of  the  Maldives  and  the  Chagos  group ;  then,  farther 
west,  the  Seychelles  group  heading  a  line  reaching  to  Newfoundland,  and 
also,  to  the  eastward,  a  line  extending  to  the  Mascarene  Islands  east  of 
Madagascar.  The  emerged  land  makes  an  off-shore  belt  for  eastern  Africa, 
somewhat  like  the  island  range  off  the  shores  of  eastern  Asia,  but  more 
continuous.  But  great  depths  now  exist  between  the  groups. 

The  identity  in  Permian  coal-plant  vegetation  is  as  great  with  Australia 
as  with  South  Africa.  The  emerged  land,  on  this  evidence,  has  been  supposed 
by  some  writers  to  have  covered  much  of  the  Indian  Ocean.  But  it  is  most 
probable  that  whatever  connection  existed  for  the  migration  of  the  plants,  it 
was  produced  by  the  spreading  of  the  Antarctic  continent  northward  to  a  line 
between  the  parallels  of  35°  and  45°  S.  The  absence  of  the  Karoo  Reptiles 
from  Australia  appears  to  indicate  that  the  connection  with  South  Africa  was 
not  complete ;  but  it  may  be  that  the  climate  of  the  northern  part  of  Ant- 
arctica was  not  warm  enough  to  favor  their  migration,  while  sufficient  for 
that  of  the  plants.  Australia  also  was  enlarged ;  for  Triassic  fossil  plants 
from  New  Zealand  and  New  Caledonia  show  that  these  islands,  as  well  as 
New  Guinea,  were  then  included  within  its  limits. 

The  idea  that  Antarctic  land  of  so  great  extent  became  emerged  in  the 
Permian  era,  or  about  that  time,  suggests  a  reason  for  the  existence  of  evi- 
dences of  glacial  phenomena  in  the  Permian  of  South  Africa,  India,  and 
Australia.  For  such  a  geographical  change  would  certainly  have  caused  a 
general  refrigeration  of  southern  climates ;  and  if  sufficient  to  produce  icy 
winters  and  glaciers  about  high  summits,  all  the  observed  facts  would  have 
their  explanation. 

DANA'S  MANUAL— 47 


III.   MESOZOTC   TIME. 

Mesozoic  or  mediaeval  time  in  the  earth's  history  comprises  a  single  era 
only.  It  is  the  era  of  the  Secondary  formations  of  early  geological  science, 
and  that  of  the  Reign  of  Reptiles  of  Agassiz. 

It  is  remarkable  as  the  era  of  the  culmination  and  incipient  decline  of 
three  great  types  in  the  Animal  Kingdom,  the  Amphibian,  Reptilian,  and 
Molluscan,  and  of  one  in  the  Vegetable  Kingdom,  the  Cycadean.  It  is  also 
remarkable  as  the  era  of  the  first  Mammals,  of  the  first  Birds,  of  the  first  of 
the  Common  or  Osseous  Fishes,  and  of  the  first  Palms  &nd.  first  Angiosperms. 

SUBDIVISIONS. 

3.  CRETACEOUS  PERIOD,  W.  H.  Fitton,  Ann.  Phil,  2d.  Ser.,  viii.,  382,  1824. 
The  Chalk  Period,  or  the  period  of  the  Chalk  formation. 

2.  JURASSIC  PERIOD,  A.  Brongniart,  Tabl  des  Terrains,  221,  1829,  the  name 

referring  to  the  Jura  limestone  and  other  related  beds  of  the  Jura 
Mountains  between  France  and  Switzerland. 

1.  TRIASSIC    PERIOD,   F.    v.    Alberti,   Beitrag    Mon.  d.  bunten  Sandsteins, 

Muschelkalks  u.  Keupers,  Stuttgart,  1834,  —  the  name,  from  the  Latin, 
referring  to  a  threefold  division  of  the  formation  in  Swabia,  Franconia, 
and  Lorraine.  Variegated  sandstone.  Buntersandstein,  this  German 
name  used  for  part  of  the  strata  by  Werner.  Poikilitic  group  (Pcecilitic) , 
Conybeare  and  Buckland  (from  the  Greek,  TTOLKL\O<S,  variegated),  Buck- 
lands  Bridgewater  Treatise,  ii.,  38, 1836.  New  Eed  Sandstone  group  or 
formation,  Lyell,  El  of  Geol,  1833, 1842  —  Mercian  of  T.  McK.  Hughes 
=  Triassic  +  Jurassic. 

The  Triassic  and  Jurassic  rocks  in  some  regions  make  together  a  continu- 
ous series,  not  easily  separated,  and  the  formation  is  then  often  called  the 
Jura-Trias. 

The  generally  accepted  subdivisions  of  the  three  periods  are  the 
following:  — 

3.  CRETACEOUS  :  (1)  Lower ;  (2)  Upper. 

2.  JURASSIC  :  (1)  Lower,  or  Liassic  (from  the  Lias,  of  England)  ;  (2)  Middle, 

or  Oolytic  (from  the  oolitic  character  of  some  of  the  limestones 
in  England)  ;  (3)  Upper,  or  Portlandian  (from  the  Portland  beds  in 
England). 

1.  TRIASSIC:  (1)  Lower  Trias,  or  Vosgian  (from  the  Vosges  Mountains); 
(2)  Middle  Trias,  or  Franconian  (from  Franconia  in  Germany)  ;  (3) 
Upper  Trias,  or  Keuperian  (from  the  name  Keuper  in  Germany)  j 
(4)  Rhcetic  (from  the  Rhsetian  or  Tyrolese  Alps) . 

738 


MESOZOIC  TIME  —  TRIASSIC  AND  JURASSIC.  739 

1.   TRIASSIC  AND  JURASSIC  PERIODS. 

AMERICAN. 

The  orographic  events  in  North  America  closing  Paleozoic  time  changed 
greatly  the  areas  of  future  rock-making.  The  map  on  page  735  shows  that  no 
marine  deposits  were  possible  on  the  Atlantic  border  except  far  outside  of 
the  present  coasc-line.  Moreover,  as  announced  on  page  734,  all  of  the  east- 
ern half  of  the  continent  had  become  dry  land,  leaving  only  the  western 
half  covered  with  the  Interior  Continental  Sea,  and  therefore  as  the  great 
arena  of  progress.  The  mostly  emerged  condition  of  the  Atlantic  border, 
indicated  on  the  map,  continued  through  the  Triassic  and  Jurassic  periods 
and  after  the  Cretaceous  period  had  opened ;  for  the  beds  of  the  Upper  Cre- 
taceous are  the  earliest  Mesozoic  marine  deposits  on  the  border.  Before 
this,  however,  in  the  Triassic  period,  there  were  large  estuary  and  fresh- water 
deposits  in  progress,  and  these  constitute  the  Triassic  formation  of  the 
Atlantic  border. 

In  this  condition  of  the  continent,  the  regions  of  Mesozoic  rock-making 
were  the  following:  (1)  the  Atlantic  border  area;  (2)  the  Gulf  border  area; 
(3)  the  area  of  the  Western  Continental  Interior;  (4)  the  Pacific  border; 
(5)  the  Arctic  area,  Arctic  rock-making  continuing  to  be  independent  of  that 
over  the  North  American  continent  in  changes  of  level  and  in  the 
formations  produced. 

The  Pacific  border  comprises  four  belts,  ranging  from  northwest  to  south- 
east, which  were  more  or  less  independent  in  their  geological  history:  — 

I.  The  Rocky  Mountain   belt,  which  includes   in  British  America   the 
Archaean  protaxis  and  the  adjoining  upturned  or  mountain  region  situated 
mainly  to  the  east  of  the  protaxis,  comprises  over  the  United   States  the 
wide  summit  region  between  the  Great  Basin  and  the  eastern  foothills  of 
the  Front  or  Colorado  Kange. 

II.  The,  Plateau  belt,  or  that  of  the  Great  Basin,  with  its  continuation 
northward  in  British  Columbia  over  the  interior  plateau  west  of  the  Gold 
Eange  or  Protaxis;    and  southward   into  Mexico,  along  the  corresponding 
plateau  region. 

III.  The  Sierra  belt,  or  that  of  the  Sierra  chain,  including  the  Sierra 
Nevada,  the  Cascade  Eange,  and  the  high  ridges  in  the  same  line  through 
British  Columbia. 

IV.  The  Coast  belt,  or  that  of  the  Coast  Kange  of  California  and  Oregon, 
and  the  Island  Eange  of  British  Columbia. 

The  interval  between  the  Sierra  and  Coast  ranges,  also,  is  in  some  respects 
entitled  to  be  considered  a  separate  belt;  but  it  is  narrow,  and  its  history 
is  mostly  involved  in  that  of  these  ranges. 

Only  in  western  North  America  have  the  Triassic  and  Jurassic  formations 
been  separately  distinguished,  and  there  at  but  few  outcrops.  Deposits  of  the 


740  HISTORICAL   GEOLOGY. 

Lower  and  Middle  Triassic  have  rarely  been  positively  identified ;  only  those 
of  the  later  part  have  been  found  on  the  Atlantic  border;  and  none  of 
either  of  the  periods  are  yet  known  to  exist  on  the  Gulf  border  beneath  its- 
Cretaceous  and  Tertiary  formations. 

\ 

ROCKS— EQUIVALENCE,  DISTRIBUTION,  AND  KINDS. 
1.  Triassic  of  the  Atlantic  Border,  or  the  Newark  Group. 

1.  Equivalence.  —  The  Triassic  beds  of  the  Atlantic  border,  according  to 
the  most  recent  authorities,  correspond  with  the  upper  part  of  the  Trias,  or 
the  Keuper  and  Khsetic  of  Europe.     The  evidence  is  based  on  the  characters 
of  the  fossil  Plants  and  Vertebrates,  marine  Invertebrates  being  absent. 

In  1819,  A.  Brongniart,  on  the  basis  of  specimens  of  fossil  fishes  of  the  Connecticut 
valley  (received  from  E.  Hitchcock),  which  he  referred  to  Palceoniscus  (Palceothris- 
sum)  Freieslebeni  of  De  Blainville  {Am.  Jour.  Sc.,  iii.,  1821,  and  vi.,  1823,  with  figures 
on  a  plate),  made  the  age  of  the  beds  Middle  Permian.  In  1835,  E.  Hitchcock  added  to 
the  evidence  from  the  fossil  fishes  additional  facts  from  the  bones  of  a  Saurian  discovered 
at  East  Windsor,  Conn.,  in  1820,  and  pronounced  the  age  that  of  the  New  Red  Sandstone, 
—  a  term  that  then  covered  both  the  Permian  and  Trias.  In  1842,  William  B.  Rogers,  after  a 
study  of  the  coal-plants  from  Virginia  beds,  referred  the  fossils  to  the  bottom  of  the  Oolyte, 
and  in  1854  to  the  base  of  the  Jurassic.  In  1855,  E.  Hitchcock,  Jr.,  concluded,  from  the 
presence,  in  the  beds  in  Massachusetts,  of  a  Fern  of  the  genus  Clathropteris,  that  the  age 
of  the  Connecticut  River  New  Red  Sandstone  was  that  of  the  Upper  Trias  and  Lower 
Lias.  In  1856,  William  C.  Redfield  advocated  the  equivalency  of  the  beds  with  the  Lias 
and  Oolyte  on  the  basis  of  the  fossil  fishes ;  and  at  the  same  time  he  proposed  the  name 
Newark  Group  (from  Newark,  N.J.)  for  all  the  Triassic  deposits  of  the  Atlantic  border. 
More  recently  the  evidence  from  the  fossil  plants  has  been  discussed,  and  the  reference  of 
the  beds  to  the  Upper  Triassic  sustained  by  Newberry,  Fontaine,  and  Ward  in  this  country,, 
and  by  Stur  and  others  abroad.  The  Vertebrate  fossils  lead  to  the  same  conclusion. 

2.  Distribution.  —  The  Triassic  beds  of  the  Atlantic  border  occur  in  long, 
narrow  independent  areas,  which  are  east  of  and  closely  parallel  to  the  Appa- 
lachian protaxis,  as  shown  on  the  map,  page  412.     They  lie  in  troughs  or 
basins  over  this  border  region  of  upturned  Archaean,  Cambrian,  and  some 
later  Paleozoic  rocks.      Over  the  region  southeast  of  New  England  these 
later  rocks  comprise  only  the  Lower  Silurian.     But  in  Nova  Scotia,  the  beds 
rest  on  the  upturned  Carboniferous,  Subcarboniferous,  and  Devonian;  and 
in  New  England,  probably  on  Devonian  or  Upper  Silurian.     The  areas  are 
nearly  parallel  in  direction  to  the  mountain  ranges  to  the  west  of  them. 

The  most  important  of  these  areas  are :  the  Acadian,  of  Nova  Scotia,  120 
miles  long ;  that  of  the  Connecticut  valley,  extending  north  and  south  along 
the  Connecticut  valley  through  Massachusetts  and  Connecticut,  110  miles 
long  and  mostly  about  20  wide ;  the  Palisade  belt,  extending  from  the  Pali- 
sades on  the  west  side  of  the  Hudson  through  New  Jersey,  Maryland,  and 
Pennsylvania  to  Orange  County,  Va.,  parallel  with  the  Appalachians,  350  miles 
long  and  mostly  10  to  30  miles  wide  j  the  Richmond  belt,  west  of  Eichmond> 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  741 

Ta.,  35  miles  long;  the  Pittsylvania  area,  farther  west  in  Virginia,  100 
miles  long,  and  40  of  the  100  in  North  Carolina,  where  it  is  called  the  Dan 
Eiver  area ;  the  Deep  River,  in  North  Carolina,  east  of  the  Dan  Kiver,  145 
miles  long,  the  last  30  of  them  separated  by  five  or  six  miles  from  the  rest, 
and  distinguished  as  the  Wadesboro  area. 

Leaving  out  of  consideration  the  Nova  Scotia  belt,  the  areas  may  be 
viewed  as  lying  in  two  ranges,  an  eastern  and  a  western,  —  the  Eastern 
including  the  Connecticut  valley,  Richmond,  and  Deep  River  areas;  the 
Western,  the  Palisade,  and  the  Pittsylvania  (and  Dan  River)  areas,  with  the 
small  intervening  Buckingham  area. 

The  following  is  a  list  of  the  areas  :  — 

(1)  The  Acadian  area,  along  the  west  margin  of  Nova  Scotia  (or  the  northeast  border 
of  the  Bay  of  Fundy),  having  a  course  nearly  northeast  to  the  south,  but  with  much  east- 
ing to  the  north  ;  and  bending  to  east  and  west  along  the  Minas  Basin  (its  north  side). 

(2)  The  Connecticut  valley  belt,  from  northern  Massachusetts  to  New  Haven  Bay, 
this  bay  being  the  southern  termination  of  the  valley. 

(3)  The  Southbury  belt,  15  miles  west  of  the  Connecticut  valley  in  Connecticut,  only 
8  miles  long  and  2J  wide. 

(4)  The  Palisade  area,  commencing  near  Haverstraw  on  the  Hudson,  30  miles  wide 
in  New  Jersey,  12  on  the  Susquehanna,  and  6  to  8  on  the  Potomac  ;  and  including  a  small 
area  in  Orange,  Va.,  which  was  probably  separated  by  erosion. 

(5)  The  Buckingham  area,  farther  south,  on  James  River,  18  miles  long  and  2  wide. 

(6)  The  Richmond  area. 

(7)  A  small  Hanover  area,  a  few  miles  north  of  the  Richmond,  but  probably  a  former 
part  of  the  Richmond. 

(8)  The  Cumberland  area,  30  miles  west  of  the  Richmond  and  mainly  in  Cumberland 
County,  22  miles  long. 

(9)  The  Pittsylvania  area,  including  the  Dan  River  of  North  Carolina. 

(10)  The  Deep  Eiver  area  of  North  Carolina,  commencing  at  Oxford  in  Granville 
County,  passing  west  of  Raleigh,  and  having  a  width  of  18  miles. 

A  Triassic  area  has  been  supposed  to  exist  on  Prince  Edward  Island,  in  the  Bay  of 
St.  Lawrence,  and  is  so  described  by  Dawson  in  his  Acadian  Geology.  According  to 
R.  W.  Ells,  the  beds  are  part  of  the  Permian  of  the  island,  with  which  they  are  conforma- 
ble (1883-84).  Bain  has  since  claimed  as  Triassic  the  upper  50  feet,  horizontal  in  position, 
occurring  on  the  north  shores  of  the  island,  near  New  London  (1885)  ;  and  Dawson 
states  in  an  appendix  to  his  work  (dated  1891),  that  the  strongest  evidence  of  Triassic 
age  for  this  part  of  the  sandstone  is  the  presence  in  it  of  Bathygnathus  borealis  of  Leidy. 
Marsh,  in  a  private  note  to  the  author,  confirms  this  view  of  Dawson,  stating  that 
Bathygnathus,  a  carnivorous  Dinosaur,  is  very  much  like  the  Triassic  forms  of  England, 
Germany,  Asia,  and  Africa. 

3.  Hocks.  —  The  rocks  are  mostly :  granitic  sandstones  (a  much  better  name 
for  them  than  the  meaningless  term  arkose)  ;  conglomerates,  varying  from 
fine  pebble  beds  to  those  consisting  chiefly  of  cobble  stones  and  larger  rounded 
masses;  sandy  shales ;  less  commonly  fine  black  carbonaceous  shales;  occa- 
sionally thin  beds  of  impure  limestone ;  and,  in  some  localities,  bituminous 
coal  in  thick  beds  along  with  carbonaceous  shales. 

In  general,  the  formation  is  well  stratified ;  but  the  strata,  when  followed 
laterally,  vary  much  in  thickness  and  coarseness.  In  some  places  borings 


742  HISTORICAL   GEOLOGY. 

have  gone  down  3000  feet  through  sandstone  alone  ;  and  seldom  are  the  inter- 
calated beds  of  limestone  and  shale  of  sufficient  extent  to  mark  a  horizon 
and  serve  as  the  means  of  measuring  the  thickness.  At  New  Haven,  Conn., 
an  artesian  boring  was  carried  down  4000  feet  through  porous  sandstone 
without  finding  variation  enough  in  texture  to  get  a  supply  of  water. 

The  layers  often  have  a  cross-bedded  structure  and  other  evidences  of 
strong  currents.  In  many  regions  they  are  here  and  there  covered  with 
ripple-marks,  mud-cracks,  raindrop  impressions,  footprints  of  Reptiles  and 
Amphibians ;  the  fine  shales  with  tracks  of  Insects  and  Crustaceans  —  facts 
which  indicate  temporary  exposures  above  the  water  level  of  great  sand-flats 
and  mud-flats.  A  slab  from  Greenfield,  Mass.,  a  dozen  feet  long,  now  in  the 
Yale  Museum,  is  covered  throughout  with  deep  impressions  of  raindrops  — 
the  work  of  a  short  large-drop  shower.  The  impressions  are  a  little  elliptical 
so  as  to  register  the  direction  of  the  accompanying  wind.  Besides  this,  two 
lines  of  large  three-toed  tracks  cross  the  slab,  and  those  of  the  longer  line 
are  dotted  by  the  raindrops,  showing  that  a  biped  reptile  had  passed  that 
way  before  the  shower  began. 

The  material  of  the  sandstones  and  conglomerates,  exclusive  of  the 
calcareous,  is  almost  solely  such  as  would  be  afforded  by  the  wear  of  granite, 
gneiss,  mica  schist,  syenyte,  and  other  crystalline  rocks  of  the  neighboring 
hills  or  mountains  ;  and  the  amount  of  mica  and  other  ingredients  and  kinds 
of  rock  material  vary  with  the  kind  of  rock  in  the  adjacent  hills.  Several 
examples  of  this  are  mentioned  by  Emerson,  Fontaine,  and  others.  The 
feldspar  is  usually  fresh  and  undecomposed,  and  well  mixed  with  the  quartz, 
showing  no  evidence  of  any  assortment  of  the  ingredients  by  beach  action. 
The  ingredients  are  often  in  proportions  fitted  to  make  granite  again  by 
subjection  to  metamorphic  action.  Mica  is  sparingly  present  except  where 
mica  schists  exist  on  the  border  of  the  areas.  There  are  also  limestone  con- 
glomerates in  regions  where  Cambrian  or  Lower  Silurian  rocks  exist  along 
the  border ;  and  occasionally  stones  of  a  quartzose  conglomerate  derived  from 
a  Cambrian  sandstone  or  quartzyte. 

The  coarsest  conglomerates  consist  of  stones  of  all  sizes  up  to  five  feet 
across,  and  usually  occur  along  the  eastern  or  western  border  of  an  area. 
In  Montague,  Mass.,  east  of  the  Connecticut,  on  the  eastern  border  of  the 
area,  and  in  Branford,  Conn.,  some  of  the  bowlders  are  three  feet  across. 
Similar  cases  exist  on  the  west  border  of  the  western  area  in  New  Jersey, 
Virginia,  and  North  Carolina.  In  the  Pittsylvania  belt,  the  larger  stones  are 
four  to  five  feet  in  diameter.  Near  Point  of  Rocks,  Md.,  the  stones  are  of 
Paleozoic  limestone,  and  some  are  two  feet  through ;  the  finer  variety  of  this 
limestone  conglomerate  is  the  "  Potomac  pudding-stone  marble." 

The  Coal-measures  in  the  Richmond  basin  and  Virginia,  and  in  North 
Carolina,  consist  of  beds  of  shale  and  sandstone  with  thick  beds  of  good  coal. 
In  the  Richmond  area  there  are  two  to  eight  coal-beds,  and  the  main  bed  is  10 
to  40  feet  thick ;  but  they  include  some  thin  dividing  layers  of  sandstone  and 
shale.  The  Coal-measures  are  situated  within  250  to  500  feet  of  the  bottom 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  743 

of  the  formation ;  and  the  same  is  true  of  those  of  the  Deep  Eiver  and  Dan 
River  areas  in  North  Carolina.  The  Connecticut  valley  area  has  some 
carbonaceous  shale,  but  no  coal. 

On  the  Virginia  belts  and  the  Richmond  coal  areas,  see  Fontaine  in  Am.  Jour.  Sc., 
1879,  and  U.  S.  G.  8.,  Memoir,  4to,  1883;  on  those  of  North  Carolina,  Emmons's 
Geol.  Eep.  of  North  Carolina,  1856,  and  Kerr's  Hep.,  1875.  Also,  for  a  general  review  of 
the  Triassic,  the  Correlation  report  of  I.  C.  Russell,  Bull.  U.  S.  G.  S.,  No.  85, 1892,  which 
contains  colored  maps  of  the  areas. 

Besides  the  sandstones  and  other  rocks  of  aqueous  origin,  there  are  in  the 
several  areas  rocks  of  igneous  origin.  These  are  described  beyond  (page 
800). 

The  thickness  of  the  Triassic  formation  in  the  several  areas  is  deter- 
mined with  difficulty,  not  only  on  account  of  the  want  of  continuous 
easily  recognized  strata  to  mark  horizons,  but  also  because  of  the  many  con- 
cealed faults  and  the  upturned  condition  of  the  beds,  as  explained  beyond. 
The  maximum  may  be,  in  some  of  the  areas,  8000  to  10,000  feet.  In  the 
Richmond  area,  Virginia,  the  thickness  has  been  made  2000  to  2500  feet. 
In  North  Carolina,  in  the  Deep  River  area,  according  to  Emmons,  it  is  3000 
feet.  Much  larger  estimates  have  been  made. 

On  the  southern  border  of  New  York,  in  Rockland  County,  at  Ramapo,  near  the 
northwestern  limit  of  the  Triassic  beds,  the  thickness,  down  to  the  underlying  gneiss, 
was  found  in  a  boring  to  be  120'  (J.  C.  Smock). 

The  large  estimates  are  obtained  by  calculation  from  the  dip,  and  the  width  at  right 
angles  to  the  dip.  By  this  very  unsatisfactory  method  a  thickness  of  12,000'  to  25,000' 
has  been  obtained.  Kerr  thus  arrived  at  a  thickness  of  10,000'.  for  the  beds  of  the  Dan 
River  area,  North  Carolina,  and  25,000'  for  those  of  the  Deep  River  area.  In  New  Jersey 
and  Pennsylvania,  according  to  B.  S.  Lyman,  there  is  a  long  longitudinal  fault  of  14,000'. 

4.  Sources  of  the  material  and  conditions  of  accumulation.  —  So  large  a  num- 
ber of  independent  belts  of  sandstone  ranging  along  for  1000  miles  is  an  un- 
usual feature  for  a  Continental  border.  It  is  not  possible  that  the  sandstone 
formation  was  made  during  a  general  submergence,  and  in  a  great  common 
body  of  water ;  for  there  is  nothing  marine  about  it  in  fossils  or  in  structure ; 
and  fresh  waters  for  the  work  could  not  have  spread  over  the  region  of  hills, 
ridges,  and  valleys,  under  any  probable  circumstances.  Moreover,  the  Nova 
Scotia  belt  occupies  the  same  Acadian  trough  which  received  deposits 
through  Paleozoic  time,  even  to  the  Carboniferous  and  Permian ;  and  the  Con- 
necticut valley  belt  is  in  the  same  trough  which  had  Silurian  and  Devonian 
beds  laid  down  in  its  northern  half,  and  possibly  also  in  its  southern  half, 
for  in  this  part  the  Triassic  formation  conceals  what  is  below.  Further, 
the  parallelism  of  the  belts  to  the  mountain  ranges  of  the  Continental  border 
is  close,  the  Palisade  trough  taking  faithfully  their  bends,  from  south  by 
west  on  the  Hudson  River,  to  west-southwest  in  Pennsylvania  (see  map, 
page  731),  and  southwest  in  Virginia,  as  if  occupying  orographic  valleys  of 
the  Appalachian  Mountain  chain.  The  facts  show  that  the  courses  of  the 


744  HISTORICAL   GEOLOGY. 

areas  were  determined  not  mainly  by  fluvial  action,  nor  by  a  great  sub- 
mergence, but  by  the  topography  of  the  Continental  border  as  it  existed 
immediately  after  the  Appalachian  upturning.  \ 

It  is  plain  that  some  of  the  areas  were  marsh  regions  along  the  courses  of 
streams  and  lakes ;  and  two  or  more  may  have  been  estuaries,  like  the 
Chesapeake  or  Delaware  Bay,  receiving  the  tides  during  part  or  all  of 
their  history.  But  it  is  also  proved  by  the  deposits  that  the  broad  streams 
sometimes  were  great  streams,  making  conglomerates  where  the  water  had 
great  velocity,  sandstones  in  gentler  currents,  shales  in  the  sluggish  waters, 
and  beds  of  vegetable  debris,  for  a  coal-bed,  where  the  conditions  were  those 
of  a  great  marsh.  As  in  other  fluvial  regions,  conglomerate-beds,  sand-beds, 
and  mud-beds  may  have  been  forming  simultaneously  at  the  same  horizon  in 
different  portions  of  an  area.  Moreover,  under  fluvial  action,  different  kinds 
of  deposits  in  flowing  waters  would  be  lengthened  out  in  the  direction  of 
the  flow,  making  unlike  formations,  longitudinal  with  the  stream,  of  parallel 
position  and  history,  looking,  to  one  traversing  the  surface,  or  studying  the 
exposed  beds,  like  consecutive  formations.  If  a  region  were  slowly  sub- 
siding so  that  the  beds  could  thicken,  there  would  probably  be,  in  a  portion 
having  like  velocity  throughout,  four  or  five  rather  prominent  kinds  of  de- 
posits, —  one  made  along  the  bed  of  the  stream ;  two  others  along  the  banks  ; 
two  others  beyond  the  banks  on  either  side ;  and  each  of  these  would  have 
their  local  belts.  These  and  other  sources  of  diversity  existed  in  the  Trias- 
sic  areas. 

Where  were  the  sources,  and  what  the  directions,  of  the  rivers  over  the 
higher  lands  from  New  York  to  North  Carolina,  which  supplied  so  generally 
granitic  sediments  instead  of  quartzose  sands  and  fine  clays,  are  questions  not 
easily  answered. 

The  recently  made  Appalachian  Mountains  stood  along  the  western  side 
of  the  Archsean  protaxis,  and  these  Triassic  formations  on  the  east  side.  It 
would  seem  to  be  a  necessary  consequence  that  the  Appalachians  should  have 
sent  off  streams  eastward  to  the  Atlantic  and  loaded  the  waters  with  Appa- 
lachian sands  and  other  detritus.  But  it  is  proved,  by  the  prevailing  granitic 
character  of  the  material  of  the  sandstones,  that  little  if  any  of  these  sedi- 
ments reached  the  Triassic  troughs,  either  from  the  Appalachian  Mountains  of 
Virginia  and  Pennsylvania,  or  from  the  plateau  region  of  Pennsylvania  and 
the  Catskills  —  the  present  sources  of  the  mud,  sand,  and  water  of  the  Dela- 
ware, Chesapeake,  and  other  streams  ;  that  the  Archaean  protaxis  was  so  high 
and  continuous  as  to  wholly  prevent  drainage  from  the  west  and  northwest ; 
that  this  range  of  crystalline  rocks  and  the  ridges  of  more  or  less  crystalline 
Cambro-Silurian,  of  the  region  in  the  vicinity,  supplied  the  streams  with 
sediments  for  transportation  to  the  Triassic  areas.  The  drainage  from  the 
Appalachian  Mountains  must  have  flowed  westward  or  southwestward. 

The  river  or  waters  of  the  time  flowing  southward  just  west  of  the  site  of 
New  York  City — where  now  flows  the  Hudson — were  25  miles  wide,  as  the 
breadth  of  the  Triassic  of  the  region  shows ;  and  they  had  sources  evidently 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC.  745 

in  the  nearer  mountains  to  the  north,  west,  and  south.  These  sources  were 
probably  in  the  Highlands  and  other  ridges  of  crystalline  rocks ;  the  waters 
and  sediment  certainly  did  not  come  from  the  Catskill  Mountains  to  the 
north,  nor  from  the  Alleghanies  to  the  west.  The  outlet  of  the  Hudson 
Eiver  of  the  period  to  the  Atlantic  is  indicated,  apparently,  by  the  submerged 
Hudson  River  channel  on  the  map  on  page  18. 

The  barrier  along  the  sea  margin  that  kept  out  salt  water  and  its  living 
species  was  evidently  the  remains  of  the  old  geanticline  referred  to  on  page 
387. 

The  coarse  conglomerate  at  or  near  the  top  of  the  sandstone  series, 
•observed  at  many  points  on  the  east  margin  of  the  Connecticut  valley  area, 
and  on  the  west  or  inner  margin  of  that  of  Maryland,  Virginia,  and  North 
Carolina,  in  which  many  of  the  rounded  stones  are  one  to  three  feet  in 
diameter,  and  also  the  similar  large  stones,  or  groups  of  stones,  occurring 
isolated  in  some  of  the  finer  sandstones,  are  remarkable  features  of  the  forma- 
tion. Rivers  cannot  transport  so  large  bowlders,  unless  down  rapid  slopes. 
The  tide  in  an  estuary  opening  seaward  only  moves  quietly,  and  usually 
makes  muddy  or  sandy  shores.  Igneous  eruptions  are  never  attended  by 
ejections  of  rounded  stones  or  bowlders.  The  stones,  excepting  those  of 
Triassic  sandstone  and  trap,  show  by  their  kinds  that  they  were  from  the 
adjoining  ridges  or  hills.  Moving  ice  would  carry  them;  but  the  Blue  Ridge 
and  other  adjoining  ridges  at  the  present  time  are  far  from  high  enough  to 
have  glaciers  about  their  summits.  The  question  arises :  Were  they  high 
enough  then  ?  Was  there,  at  or  near  the  close  of  the  period,  an  epoch 
of  unusual  cold  having  icy  winters  and  covering  the  adjoining  ridges  with 
glaciers  that  carried  bowlders,  and  made  streams  that  bore  floating  ice  laden 
with  stones  out  over  the  river  or  estuary  waters  ? 

5.  Subsidence  in  progress  during  the  deposition.  —  Since  a  thickness  of 
some  thousands  of  feet  was  acquired  in  the  several  areas  by  the  strata,  and 
the  beds  often  bear  evidence  in  their  ripple-marks,  mud-cracks,  and  foot- 
prints of  shallow-water  origin,  each  of  the  troughs  of  valleys  must  have  been 
undergoing,  during  the  slow  accumulation,  a  concurrent  subsidence  of  as 
many  thousands  of  feet.  On  the  upturning  of  the  beds  and  other  orographic 
phenomena  see  page  798. 

Economical  products.  —  The  coal-beds,  already  described,  are  a  prominent  part  of 
these  products.  Veins  containing  copper  ores  occur  in  Connecticut,  New  Jersey,  Pennsyl- 
vania, which  have  been  worked ;  but  none  are  now  producing  ore.  The  copper  ores  are 
•chiefly  chalcocite  and  bornite,  with  occasionally  native  copper.  One  mass  of  native  copper 
found  in  the  drift  north  of  New  Haven,  Conn.,  weighs  nearly  200  pounds.  A  copper  mine 
at  Bristol,  Conn.,  which  was  for  awhile  productive,  is  situated  on  the  western  border  of  the 
Triassic,  in  the  crystalline  rocks  outside  of  the  sandstone  area,  but  belongs  to  a  fissure  of 
the  Triassic  series.  Barite  often  accompanies  the  ore,  and  sometimes  is  the  chief  mineral 
of  the  vein,  and  occasionally  occurs  in  crystals  weighing  over  100  pounds.  A  vein  in 
Cheshire,  Conn.,  now  exhausted,  yielded  a  large  amount  of  the  mineral  for  the  adulteration 
of  white  lead,  and  for  calsomining  and  other  purposes. 

The  beds  of  sandstone  afford  much  rock  for  building  purposes.     The  rock  so  used  is 


746  HISTORICAL   GEOLOGY. 

often  called  brownstone.  The  material  of  many  of  the  "brownstone  fronts"  of  New 
York  and  other  eastern  cities  is  mostly  from  this  formation.  The  Potomac  conglomerate 
marble  is  used  as  an  ornamental  stone,  and  columns  of  it  stand  in  the  Capitol  at 
Washington. 

2.  The  Triassic  and  Jurassic  of  the  Western  Interior  and  Pacific  Border  Regions.. 

The  Triassic  and  Jurassic  formations  of  the  Western  Interior  and  of  the 
Pacific  border  have  a  wide  distribution,  and,  to  some  extent,  distinguishable 
limits.  The  former  consist  almost  everywhere,  in  the  Interior,  of  reddish 
sandstones  and  marly tes,  and  are  often  called  "  Red  Beds."  They  frequently 
contain  gypsum  and  sometimes  salt.  Upon  the  Pacific  Ibrder  the  rocks  of 
this  period  are  chiefly  slates,  with  occasional  sandstones,  and  much  limestone. 

The  Jurassic  beds  are  usually  of  lighter  shades  of  color,  and  are  in  most 
regions  partly  or  chiefly  calcareous,  and  the  limestone  is  often  cherty.  A 
large  part  of  the  Triassic  formation  is  without  fossils,  excepting  occasional 
traces  of  plants;  but  the  Jurassic  is  often  fossiliferous,  though  seldom 
prolific  in  species. 

Triassic. 

Over  the  Continental  Interior,  the  Triassic  formation  is  exposed  to  view 
in  northern  Texas,  adjoining  Indian  Territory  and  western  Kansas.  The 
beds  probably  underlie  the  Cretaceous  beds  farther  northward,  but  no  out- 
crops occur  in  that  direction  except  in  mountainous  regions  to  the  west  and 
northwest.  They  exist  about  the  Black  Hills  of  Dakota,  and  cover  large 
areas  along  the  Summit  Region  of  the  Rocky  Mountains  in  New  Mexico, 
Colorado,  and  Utah,  east  of  the  western  limit  of  the  Wasatch  Range,  and 
also  in  Wyoming,  Montana,  and  Idaho.  In  British  America,  east  of  the 
Archaean  protaxis,  they  have  been  observed  on  Peace  and  Pine  rivers, 
beyond  55°  N.  and  between  122°  and  125£°  W. ;  and  also  on  Liard  River, 
near  59°  N.  Beds  in  southeastern  Idaho,  near  Soda  Springs,  have  been 
referred  to  the  Lower  Trias  (Mojsisovics,  Hyatt)  ;  but  the  absence  or  non- 
discovery  of  fossils  leaves  the  age  of  the  beds  of  the  Rocky  Mountains  and 
Interior  Continental  regions  generally  undetermined. 

West  of  the  meridian  of  the  Wasatch  Mountains,  and  of  the  Rocky  Moun- 
tain protaxis  in  British  America,  over  the  Great  Basin  plateau,  and  its  con- 
tinuation in  the  plateau  region  of  British  Columbia,  the  Trias  appears  to  have 
a  wide  range.  In  the  United  States  it  is  confined  to  the  west  side  of  the 
plateau  or  Great  Basin  beyond  1171°  W.,  on  the  40th  parallel.  In  the  west 
Humboldt  region,  according  to  King,  15,000  feet  of  beds,  partly  Middle  Trias, 
underlie  4,000  feet  or  more  of  Jurassic  beds.  In  the  plateau  region  of 
British  Columbia,  Triassic  areas  occur  on  Nicola  Lake  (50°  N.,  1201°  W.) 
and  Stikine  River  (57°  K,  1371°  W.). 

Farther  west,  in  the  Sierra  belt,  beds  of  the  Upper  Triassic  occur  near 
the  summit  of  the  Sierra  Nevada  in  Plumas  County,  Cal.,  as  first  identified 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  74T 

by  Gabb  from  fossils  discovered  during  the  Whitney  Geological  Survey 
(1864),  and  later  studied  over  the  Taylorville  region  by  Diller  and  Hyatt 
(1892).  The  thickness  of  the  Triassic  in  this  region  is  about  4800  feet,  and 
of  the  overlying  Jurassic  sandstones,  limestones,  and  tufa  about  2000  feet. 
The  formation  is  continued  northwestward  into  the  Klamath  Mountains. 
Whether  it  exists  in  the  Cascade  Range  still  farther  north  is  unknown,  as 
these  mountains  are  mostly  under  recent  volcanic  rocks. 

The  Island  belt  in  British  Columbia  contains  areas  of  Upper  Triassic  on 
Vancouver  Island,  Queen  Charlotte  Islands,  in  the  Straits  of  Georgia;  and 
beyond  they  occur  at  Wrangel  Bay,  Alaska. 

Upper  Triassic -beds  occur  also  in  Mexico,  in  the  states  of  Sonora  (New- 
berry,  1876),  Puebla  and  Oasaca  (Aguilera  and  Ordonez,  1893).  They  are 
found  also  in  Honduras  (Newberry,  1888). 

In  the  Black  Hills,  the  Triassic  beds,  or  the  "Red  Beds"  supposed  to  be  Triassic, 
come  to  the  surface,  along  with  the  Jurassic,  from  beneath  the  Cretaceous  beds  of  the 
Continental  Interior,  as  first  shown  by  Meek  (1858,  1860).  They  are  mainly  arenaceous 
clays,  unfossiliferous,  300'  to  400'  thick,  with  15'  to  30'  of  impure  limestone  below  the 
middle,  and  with  gypsum  in  the  upper  half.  In  the  foot  hills  east  of  the  Front  Range  in 
Colorado,  the  Triassic  and  Jurassic  often  appear  overlying  the  Archaean,  or  the  Paleozoic* 
600'  to  1000'  of  the  former,  to  200'  or  300'  of  the  latter.  In  these  foot  hills,  to  the  west- 
ward, within  30  miles  of  the  line  of  New  Mexico,  and  for  50  miles  beyond,  as  stated  by 
Stevenson,  the  Cretaceous  rests  on  the  Carboniferous  over  Archaean,  the  Triassic  not 
extending  so  far  west. 

Bordering  the  Laramie  Plains,  in  Wyoming,  these  formations  may  be  seen  over 
Archaean  ;  the  gypsum  beds  of  the  Triassic  are  sometimes  over  20'  thick. 

In  Idaho,  north  of  the  Wasatch,  between  the  Wyoming  and  Portneuf  ranges  (HOJ0- 
112°  W.),  upturned  Triassic  and  Jurassic  beds,  according  to  A.  C.  Peale  (1879),  enter 
largely  into  the  structure  of  the  ridges ;  and  these  formations  in  the  Blackfoot  Basin, 
where  the  Triassic  is  about  4000'  thick  and  the  Jurassic  1500'  (more  than  half  limestones), 
afforded  the  fossils  described  by  C.  A.  White  in  1879  (page  758).  In  the  Wasatch 
there  are  1000'  to  1200'  of  Trias  overlaid  by  1600'  to  1800'  of  Jurassic  beds  (King).  In 
the  High  Plateaus  to  the  south,  north  of  the  Colorado  Canon,  the  "Vermilion  Cliffs"  of 
Powell,  1000'  to  1500'  high,  which  extend  for  100  miles  from  Hurricane  fault  to  Paria,  and 
the  "  Shinarump  Cliffs"  below,  are  Triassic,  while  the  overlying  "  White  Cliff  group," 
2000'  or  more  thick,  consisting  of  white  sandstone  and  calcareous  beds,  and  the  "  Flaming 
Gorge  group  "  in  Utah,  are  referred  with  some  doubt  to  the  Jurassic.  The  beds  are  con- 
tinued southward  in  plateaus  of  Arizona  and  New  Mexico. 

The  Trias  of  western  Nevada  consists,  according  to  King,  of  a  lower  Koipato  group  of 
siliceous  and  argillaceous  beds,  5000',  and  above  this,  great  limestone  strata  and  alternating 
quartzyte  of  the  Star  Peak  groups,  10,000'.  The  Trias  of  this  region  may  have  once  been 
connected  with  that  of  the  Sierra  Nevada  just  west. 

Upon  the  northern  end  of  the  Sierra  Nevada,  near  Taylorville,  Diller  measured  nearly 
5000'  of  Upper  Trias.  It  lies  apparently  unconformably  upon  both  sides  between  the  Jurassic 
and  Carboniferous.  It  consists  below  of  200'  of  slates  overlaid  by  140'  of  limestone,  and 
above  of  over  4000'  of  sandstones  and  slates.  In  the  two  lower  members  fossils  are  often 
abundant,  but  in  the  upper  slates  they  are  rare  and  chiefly  land  plants.  The  limestone  is 
most  persistent,  and  has  been  recognized  by  its  fossils  near  Pit  River  and  elsewhere  in  the 
Klamath  Mountains,  and  even  as  far  north  as  Siskiyou  County,  near  the  Oregon  line. 
The  presence  in  that  region  of  large  masses  of  eruptive  material,  often  fossiliferous,  shows 


748  HISTORICAL  GEOLOGY. 

that  volcanic  forces  were  vigorously  active,  not  only\during  a  portion  of  the  later  Trias, 
but  also  in  the  earlier  Carboniferous  and  later  Jurassic. 

The  Trias  was  first  recognized  as  existing  probably  in  Sonora,  Mexico,  by  A.  R6mond 
(J.  D.  Whitney,  Am.  Jour.  Sc.t  1866).  He  speaks  of  it  as  consisting  of  sandstones  and 
conglomerates  with  coal-bearing  clay  shales.  He  adds  that  the  metamorphic  slates  of  the 
Altar  and  Magdalena  districts,  which  include  the  richest  gold  placers  of  Sonora,  may 
possibly  be  of  Triassic  age,  but  that  it  is  also  possible  that  they  are  Jurassic,  as  they 
«•  resemble  rather  the  Jurassic  gold-bearing  slates  of  the  Sierra  Nevada." 

Jurassic. 

Jurassic  beds  are  found  at  the  west  base  of  the  Black  Hills  in  Dakota, 
where  the  rock  is  limestone  with  intercalated  marls.  The  thickness,  200 
feet,  increases  to  600  feet  40  miles  from  the  Hills  (Newton),  indicating,  as 
W.  0.  Crosby  implies,  less  subsidence  in  the  sea-bottom  about  the  Archaean 
center  than  at  a  distance  from  it.  They  also  come  out  to  view  at  points 
along  the  base  of  the  Laramie  Mountains,  the  Big  Horn  Mountains,  the  Wind 
Biver,  and  other  mountains  in  the  Bocky  chain.  They  overlie  Triassic 
through  much,  of  the  Summit  Begion  within  the  United  States,  both  east  of 
the  Great  Basin  or  Plateau  belt,  and,  as  has  been  mentioned,  along  its 
western  border  beyond  117|°.  Farther  north  in  the  same  belt,  they  have 
been  observed  by  Diller  on  the  Blue  Mountains  of  Oregon. 

The  Upper  Jurassic  in  Colorado,  Wyoming,  and  Montana  includes  the 
freshwater  Atlantosaurus  beds  of  Marsh,  from  100  to  300  feet  thick,  which, 
have  afforded,  near  Morrison  and  Canon  City  in  Colorado  and  elsewhere,  the 
remains  of  many  large  Beptiles,  teeth  and  jaws  of  Marsupial  and  Oviparous 
Mammals.  The  Baptanodon  beds  of  Marsh,  when  present,  are  next  below. 
They  contain  remains  of  large  aquatic  Beptiles,  besides  some  marine  inverte- 
brate fossils. 

The  Jurassic  beds  are  found  along  a  large  part  of  the  western  slope  of 
the  Sierra  Nevada.  The  first  discoveries  were  made  in  Plumas  County,  on 
the  north  slope  of  Genesee  valley,  by  Clarence  King,  of  the  Whitney  Survey, 
in  1863.  They  were  afterward  discovered  in  the  auriferous  slates  of  the 
Mariposa  region  and  identified  by  fossils  (Gabb,  1864;  Meek,  1865). 

In  the  Taylorville  region  in  Pluinas  County,  the  Jurassic  beds,  according  to  Diller  and 
Hyatt,  are  found  to  consist  of  nearly  1500'  of  sandstones,  10'  to  30'  of  limestones,  and  500' 
of  tufa.  The  series  represents,  as  Hyatt  has  found  from  the  fossils,  the  Lias  and  the 
Lower  and  Upper  Oolyte.  The  Upper  Oolyte  has  also  been  identified  by  fossils  over  a 
wide  range  of  the  western  slopes  of  the  Sierra,  where  the  rocks  are  upturned  metamorphic 
slates,  hydromica,  mica,  and  siliceous  schist,  with  sandstone,  and  in  some  parts,  serpentine, 
and  thin  beds  of  crystalline  limestone,  besides  more  coarsely  crystalline  rocks.  The  belt 
of  slates  —  which  is  in  general  20  to  25  miles  wide  —  contains  the  chief  part  of  the  gold- 
bearing  veins  of  quartz,  some  of  which  are  of  great  width.  Turner  describes  the  Mariposa 
slates  as  including  much  diabase  tufa,  besides  some  conglomerates  made  of  siliceous 
pebbles  from  the  associated  rocks  (1894). 

The  most  abundant  fossil  in  the  Mariposa  beds  is  a  species  of  Aucella  (see  beyond, 
page  760),  and  hence  related  beds  have  been  called  Aucella  beds.  The  Mariposa  rocks 
were  pronounced  Jurassic  by  Gabb  (1864)  and  Meek  (1865),  and  recently  also  by  Hyatt. 


MESOZOIC   TIME  —  TBIASSIC   AND  JURASSIC. 


749 


The  Lias  and  earlier  Oolyte  appear  to  be  unrepresented  along  the  Coast  region  and 
Plateau  belt  of  British  America  (G.  M.  Dawson). 

Jurassic  beds,  related  in  fossils  to  those  of  Taylorville,  occur  also  in  the  Pit  Kiver 
region  on  the  western  and  northern  borders  of  the  Sacramento  valley,  with  Triassic  and 
Carboniferous  below,  and  are  covered  unconf ormably  by  the  Cretaceous ;  also  on  the 
upper  waters  of  Crooked  Kiver,  in  the  Blue  Mountains  of  Oregon ;  and,  according  to  Hyatt,, 
these  areas  were  connected,  during  the  Lias,  with  that  of  western  Nevada. 

Small  Jurassic  areas  are  laid  down  on  Castillo's  geological  map  of  Mexico,  in  the  states 
of  Sonora,  Coahuila,  San  Luis  Potosi,  Queretaro,  Hidalgo,  Puebla,  and  others  near  the  east- 
ern border  of  the  great  central  plateau,  and  also  in  Colima  near  the  coast.  The  beds, 
according  to  Aguilera  and  Ordonez  (1893),  contain  Aucellse,  and  Ammonites  of  the  genus. 
Perisphinctes,  and  pass  conformably  into  the  overlying  Cretaceous. 

In  the  Arctic  Regions,  the  Jurassic  (Lias  ?)  has  been  identified  far  north  on  Prince 
Patrick  Island  and  near  the  northwest  extremity  of  Bathurst  Island,  and  on  Exmouth 
Island  and  other  places  in  the  vicinity.  At  the  locality  on  Bathurst  Island,  a  vertebra  of 
a  Saurian,  Arctosaurus  Osborni,  has  been  found  ;  and  on  Exmouth  Island,  remains  of  an 
Ichthyosaurus. 

The  Jura-Trias  regions  of  part  of  Utah  and  Nevada  are  mapped  (in  colors)  in  King's 
40th  Parallel  Report  (1878);  and  of  Idaho  and  part  of  Utah,  by  Peale,  Endlich,  and  St. 
John,  in  the  Hayden  Expedition  Report  for  1878 ;  and  of  part  of  California  by  Diller 
(1893)  in  the  Atlas  of  the  U.  S.  Geological  Survey,  on  the  sheets  of  the  Lassen  Peak 
district. 


1156-1160. 


1157 


Fig.  1156,  Podozainites  Emmonsi;  1157,  Pterophyllum  Riegeri;  1158,  Clathropteris  rectiuscula;  1159,  Oligo- 
carpia  (Pecopteris)  robustior,  part  of  a  frond  in  fructification ;  1160,  Tseniopteris  linnseifolia.  Figs.  1156- 
1169,  E.  Emmons ;  1160,  E.  Hitchcock,  Jr. 


750  HISTORICAL  GEOLOGY. 

LIFE. 

1.   Triassic  of  the  Atlantic  Border. 

PLANTS.  —  The  vegetation  of  the  Triassic  was  characterized  not  by 
Sigillarids  and  Lepidodendrids,  like  that  of  the  Carbonic  era,  but  by  Cycads, 
Conifers,  Ferns,  and  Equiseta. 

As  the  Cycads  were  a  prominent  feature  of  the  forests  in  both  the  Triassic 
and  Jurassic  periods,  a  figure  of  a  common  East  India  species,  Cycas  circincdis 
(  X  Y^)  is  given  on  page  434.  Its  relation  to  Conifers,  both  groups  being 
G-ymno sperms,  notwithstanding  its  palm-like  foliage,  has  already  been 
explained.  Portions  of  leaves  of  two  species  related  somewhat  to  the 
modern  Zamia  are  represented  in  Figs.  1156  and  1157. 

Conifers  existed  of  the  genera  Voltzia  (differing  little  from  Walchia  of 
the  Permian,  page  705),  Baiera,  and  Araucarites.  Stems,  leaves,  cones,  and 
trunks  of  such  trees  are  not  uncommon.  Ferns  were  numerous,  of  the  genera 
Pecopteris  (Fig.  1159),  Tceniopteris :  (Fig.  1160),  Clathropteris  (Fig.  1158), 
and  others  related.  Some  of  the  Equiseta  (Calamites)  had  a  breadth  of 
stem  of  four  inches  or  more. 

ANIMALS.  —  The  Triassic  beds  of  the  Atlantic  border  have  afforded  no 

marine  species  of  any  kind;  all  are 


1  "I  f\Q 

either  of  fresh  or  brackish  waters,  or 
else  terrestrial, 
lies  1.  Crustaceans  and  Insects.  —  The 

Crustaceans    observed    are     mostly 
Ostracoids.     The  little  shells  (Figs. 
Figs.  H61-1163,  Estherta  ovata.    Fig.  1161,  Lyeii;    H61-1163)    are    abundant   in   some 

1162,  E.  Emmons  ;  1163,  L.  Sanford. 

beds  oi  shale. 

The  presence  of  Insects  is  known  from  their  tracks  and  from  the  discovery 
of  the  larves  of  one  species.  These  larves  (Fig.  1164)  were  found  by  E. 
Hitchcock  rather  abundantly  in  shales  at  Turner's  Falls,  and  have  since 

1164-1169. 

1164 


1165       f\     1166  Lb7     I       1168^        ^  \          1169 


A   r  (> u     v  v 

*     '     ^'  w    \  ^     \ 

s\          P\     \l    \J  \ 


fir 

l»     *N 


y'V  U    U 


U     M 

\l    W        N  . 

/\       ,.    I/  \ 

'          V|    \J        v      ^        \ 


INSECTS.  — Fig.  1164,  Insect  larve,  Mormolucoides  articulatus ;  1165-1167,  tracks  of  Insects;  1168, 1169,  tracks 
of  Crustaceans  (?).    Fig.  1164,  from  Scudder ;  1165-1169,  E.  Hitchcock. 

been  obtained  at  Montague,  and  at  Horse  Race  in  Gill,  Mass.     The  Insect 
was  a  Neuropter.     Figs.  1165  to  1167  are  of  tracks  from  the  Connecticut 


MESOZOIC   TIME  —  TRIASSIC    AND   JURASSIC. 


751 


valley  beds,  referred  by  E.  Hitchcock  to  Insects,  and  the  others  (1168,  1169) 
are  regarded  by  him  as  made  by  Crustaceans.  Nearly  30  species  of  these 
delicate  tracks  are  described  by  Hitchcock. 

2.  Fishes. — The  Fishes  of  the  era  were  Ganoids  and  Sharks,  but  only 
remains  of  Ganoids  have  been  found  in  the  American  rocks ;  one  of  them, 
from  black  shales  at  Durham,  Conn.,  is  represented,  reduced,  in  figure 
1170.  The  largest  species  found  is  Diplurus  longicaudatus  Newb.,  about 
three  feet  long.  Unlike  Paleozoic  Ganoids,  the  Triassic  species  are  not  all 
heterocercal ;  many  have  the  tails  partly,  or  not  at  all,  vertebrated;  and 
this  is  the  last  period  in  which  the  old  Paleozoic  characteristic  appeared. 
Thus,  as  Agassiz  first  observed,  the  progress  of  the  ages  was  marked  in  the 

tails  of  the  fishes. 

1170. 


1171-1172. 


1171 


1172 


GANOID.  —  Catopterus  gracilis  (x  $).    J.  H.  Kedfield. 

3.  Amphibians.  — Portions  of  large  crania  have  been  found  in  black  shale 
in  Chatham  County,  N.C.,  and  in  a  literal  "  bone-bed "  at  Phoenixville,  Pa. 
With  the  latter  were  teeth  two  inches  long,  of  a  spe- 
cies named  Eupelor  durus  by  Cope.     The  figures  of 

footprints  annexed,  1171,  1171  a,  and  1172,  1172  a 
(half  to  two  thirds  the  natural  size),  are  the  fore  and 
hind  feet  of  probably  two  Amphibians  (Hitchcock). 
The  tracks  were  from  the  Connecticut  valley  beds. 

4.  Reptiles.  —  The    Reptiles    pertain   to   the   two 
grand  divisions  of  Dinosaurs  and  Crocodilians. 

Dinosaurs. — The  Dinosaurs  are  mostly  of  large 
size,  and  were  so  named  by  Owen,  from  Setvds,  terrible, 
and  o-avpos,  lizard.  They  are  more  or  less  bird-like  in 
some  characteristics ;  these  all  having  (1)  the  posterior 
limbs  the  stouter,  as  in  Fig.  1179,  page  753,  and  some- 
times these  are  the  only  locomotive  limbs,  the  Reptiles 
in  that  case  being  bipeds  in  walking,  like  birds; 
(2)  the  bones  of  the  limbs,  especially  the  anterior, 
often  hollow ;  and  in  some,  the  vertebrae  of  the  neck 
very  cellular  and  light ;  (3)  of  the  pelvic  bones  the 
ischium  (is,  Fig.  1179)  is  a  long  and  often  slender  bone 

projecting  backward,  and  the  pubes  also  are  long.     Many  herbivorous  Dino- 
saurs that  were  not  biped  in  locomotion  used  their  strong  hind  limbs  for 


1172  a 


AMPHIBIANS.— Fig.  1171, 1171  a 
(x  £),  Amsopus  Deweyanua ; 
1172, 1172  a,  A.  gracffls  (x  |). 
E.  Hitchcock. 


752 


HISTORICAL   GEOLOGY. 


holding  their  bodies  raised  against  trees  or  other  objects;  and  hence  there- 
was  great  convenience  in  having  the  bones  of  the  anterior  part  of  the  body 
cellular  and  thereby  light. 

1173-1177. 


1178. 


DINOSAUBIANS. — Fig.  1173,  Macropterna  divaricans  (x  $);  1174,  Apatichnus  bellus  (x  $);  1175,  Anomoepu& 
scambus,  fore  foot  (x  J);  1175  a,  hind  foot  of  same ;  1176,  Otozoum  Moodii,  fore  foot ;  1176  a,  hind  foot  of 
same  (both  x^)  ;  1177,  Brontozoum  giganteum  (x£).  All  from  Hitchcock. 

The  track  represented  in  Fig.  1177  occurs  from  14  to  18  inches  in  length, 
and  was  made  by  one  of  the  biped  Dinosaurs ;  it  is  the  Brontozoum  giganteum 

of  Hitchcock.  The  tracks  1175,  1175  a, 
also  much  reduced,  are  of  another  bird-like 
Dinosaur,  but  one  that  had  three-toed  feet 
behind  (1175  a),  and  a  small  four-fingered 
hand  in  front  that  was  only  occasionally 
brought  to  the  ground.  The  track  1176  ar 
20  inches  long  natural  size,  is  of  the  hind 
foot  of  an  Otozoum,  a  gigantic  Dinosaur  that 
usually  walked  erect,  biped-like ;  its  much 
smaller  fore  feet  (1176)  served  as  hands, 
for  they  were  seldom  brought  to  the  ground. 
The  stride  of  the  Otozoum  was  a  yard  in 
length.  The  other  lines  of  tracks,  1173  and 
1174,  are  of  species  that  walked  on  all  fours. 
These  tracks  indicate  three  kinds  of 
Dinosaurs :  (1)  bipeds  with  the  hind  feet 

3-toed ;  (2)  bipeds  with  the  hind  feet  four- 
Blab  of  sandstone,  with  footprints.   Hitchcock. 

toed;   (3)  quadrupeds  walking  on  all  fours. 
A  slab  of  sandstone,  with  its  footprints  in  several  series,  is  represented  in 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC. 


Fig.  1178;  it  is  reduced  to  ^  the  natural  size,  excepting  the  two  tracks 
lettered  a,  which  are  enlarged  views  of  the  tracks  of  the  line  b.  No  tracks 
of  fore  feet  have  been  found  with  them,  and  hence  it  is  thought  possible  that 
some  are  tracks  of  Birds.  But  no  positive  evidence  of  Birds  has  been  found. 
The  collection  of  Amherst  College,  and  that  of  Yale  at  New  Haven, 
contain  each  several  thousands  of  tracks  from  the  Connecticut  valley  ;  a  fact 
that  gives  some  idea  of  the  abundance  of  life  on  the  continent  in  Triassic  time. 
Other  estuaries  and  valleys  besides  those  now  occupied  by  Triassic  beds  were 
probably  equally  populous.  Twenty-one  consecutive  tracks  of  the  Otozoum 
were  exposed  to  view  in  1874,  at  one  of  the  quarries  at  Portland,  Conn. 

Bones  of  the  Dinosaurian  Reptiles  were  first  found  in  1818,  in  the  sand- 
stone of  East  Windsor,  Conn.,  and  near  Springfield,  Mass. ;  and  the  foot  of  one 
1179.  from  the  latter  locality  was  figured  in  1865  by  Hitchcock, 

who  (in  allusion  to  the  length  of   the  bones)  named  the 
species  Megadactylus  polyzelus;  and  in  1870  the   Reptile 
was  described  and  pronounced  a  Dinosaur  by  Cope.   Remains 
have  since  been  discovered  in  North  Carolina,  Pennsylvania, 
and   Prince   Edward   Island,    and    again   in   Connecticut. 
Near  Manchester,  Conn.,  large  portions  of  four  skeletons  of 
the  same  genus,  and  of  another,  Ammosaurus,  have  been 
obtained  by  Marsh.     Fig.  1179  represents  a  restoration 
published  by  him  in  1893.     The  name  Megadacty- 
-  lus  being  preoccupied,  it  is  changed  by  him 
to  Ancliisaurus.     It  was  one  of  the  car- 
nivorous Dinosaurs  that  left  tracks 
on  the  sandflats  and  mudflats  of 
the  Connecticut  valley  estuary. 


Fig.  1179,  restoration  of  Anchisaurus  colurus  Marsh  (x^).    p,  pubis ;  w,  ischium ;  /,  femur. 

Other  Dinosaurs  are :  Clepsysaurus  Pennsylvanicus  of  Lea,  from  Phoenixville, 
Pa.,  Fig.  1181 ;  Bathygnathus  borealis  of  Leidy,  from  Prince  Edward  Island, 
DANA'S  MANUAL  —  48 


754 


HISTORICAL   GEOLOGY. 


a  tooth  of  which,  from  a  skull  described  and  figured  by  him,  is  represented 

half  the  natural  size  in  Fig.  1180;  the 

1180-1183.  1182       teeth    were    four     inches    long;     also, 

ii8i  L82a  j&  Palceoctonus  Appalachians  Cope,  from 
Phcenixville ;  an  anterior  tooth  having 
a  length  of  3J  inches  ;  also  Thecodon- 
tosaurus  gibbidens  Cope,  Palceosaurus 
Fraserianus  Cope,  Suchoprion  aulacodus 
Cope,  from  Phoenixville. 

Crocodilians.  —  The  Crocodilians  are 
Thecodont  species  (that  is,  have  the 
teeth  in  sockets).  They  pertain  to  the 
genus  Belodon,  and  are  characterized  by 
the  Palaeic  features  of  biconcave  verte- 
brae ;  the  jaws  were  long  and  slender,  like 
those  of  the  Gavials.  Teeth  of  two 
species  are  represented  in  Figs.  1182, 
1182  a,  Belodon  prisons  of  Leidy,  and 
Fig.  1183,  B.  Carolinensis  of  Cope,  from 
Pennsylvania  and  North  Carolina. 

Bones  of  one  species  have  been  found  by  Marsh  in  the  Connecticut  sandstone. 

Coprolites  are  common  in  the  shales  at  Phoenixville,  Pa. 

5.  Mammals.  —  The  only  Mammalian  remains  of  the  Atlantic  border  are  two 

jaw-bones,  found  in  Chatham  County,  K  C.,  by  E.  Emmons.     They  belong  to 

1184-1185. 


1184  a 


DINOSAURS.  —  Fig.  1180,  Bathygnathus  borealis; 

1181,  Clepsysaurus  Pennsylvanicus. 
CEOCODILIANS.  —  Fig.   1182,    tooth    of  Belodon 

priscus ;   1182  a,  section  of  same ;   1183,  B. 

Carolinensis.     Fig.  1180,  Leidy;    1181-1183, 

E.  Emmons. 


1185  a 


MARSUPIAL   MAMMALS. 


Fig.    1184,  Drornatherium   sylvestre  (x3);   1184  a,  id.  (x  1) ;    1185,  Mtcroconodon 
tenuirostris  (  x  4)  ;  1185  a,  id.  (x  1).    Osborn. 


Insectivorous  Marsupials,  Dromatherium  sylvestre  of  Emmons,  and  Microco- 
nodon  tenuirostris  of  Osborn.*  Mammals  of  similar  character  probably 
spread  over  the  continent,  and  may  have  been  of  many  species. 

*Owen  says  of  the  Dromatherium  that  "  this  Triassic  or  Liassic  Mammal  would  appear  to 


MESOZOIC   TIME— TRIASSIC    AND   JURASSIC.  755 

Characteristic  Species. 

PLANTS  OF  THE  EASTERN  BORDER  TRIASSIC.  —  For  figures  and  descriptions  of 
Virginia  and  North  Carolina  plants,  see  Fontaine's  Report,  containing  53  plates,  which 
contains  also  the  figures  in  Emmons's  N.  Car.  Eep.  of  1853,  and  in  his  American  Geology  ; 
also,  for  those  of  other  localities,  Newberry,  U.  S.  G.  8.,  4to,  1888.  The  plants  are 
referred  to  the  Upper  Triassic  by  Fontaine,  Newberry,  and  L.  F.  Ward.  D.  Stur,  of 
Vienna,  after  a  study  of  the  figures  and  specimens,  concludes  (  Verh.  G.  Reichsanst.,  1888, 
and  Am.  Jour.  Sc.,  xxxvii.,  1889)  that  over  a  dozen  of  the  Virginia  species  are  identical 
with  Austrian  plants  from  the  Lettenkohle  or  Lower  Keuper  of  Lunz  and  other  European 
localities.  Fontaine  states  that  the  plants  collected  in  Virginia  are  mostly  from  the 
Richmond  Coal-measures,  and  therefore  from  the  lower  part  of  the  Triassic  formation, 
while  those  of  North  Carolina  are  from  a  higher  horizon ;  and  that  a  number  of  species 
from  the  latter  region  are  related  to  the  Rhsetic  of  Europe,  and  2  are  probably  identical 
with  species  of  the  Lias.  According  to  Newberry  only  6  to  8  of  the  few  species  of  New 
Jersey  and  the  Connecticut  River  valley  are  identical  with  those  of  Virginia.  The  black 
shale  of  Durham,  Conn.,  has  afforded  5  of  these  species.  He  also  states  that  several 
North  Carolina  species  are  found  at  Abiquiu  in  New  Mexico,  and  Los  Bronces  in  Sonora, 
Mexico,  rendering  it  probable  that  the  beds  are  alike  Upper  Triassic. 

Dawson  has  described  Dadoxylon  Edwardianum  and  Cycadeoidea  Abequidensis,  from 
Prince  Edward  Island. 

ANIMALS.  —  Footprints  appear  to  have  been  first  critically  observed  in  the  Connecticut 
valley  by  J.  Deane  of  Greenfield,  Mass.,  in  1835,  and  made  known  by  him  to  E.  Hitchcock. 
The  latter  in  1836  began  his  extended  collection  and  study  of  the  footprints,  and 
his  publications  thereon;  .first  in  1836,  of  7  species  (Am.  Jour.  /Sc.),  and  later  in  his 
Hep.  Geol.  Mass.,  1841,  and  his  Reports  on  Ichnology  in  4to,  of  1848  and  1858  and 
1865.  He  first  made  all  3-toed  tracks  ornithic ;  but  later  proved  this  erroneous  by 
finding  impressions  of  the  fore  feet.  In  1837,  discoveries  were  made  in  Connecticut  by 
William  A.  Redfield,  and  later  others  in  New  Jersey  and  Pennsylvania.  Deane  pub- 
lished papers  in  1844, 1845,  and  later ;  and  a  posthumous  volume  on  Ichnographs,  from  his 
notes,  by  T.  T.  Bouve,  appeared,  in  4to,  in  1861.  See  also  publications  of  Boston  Soc.  N. 
Hist,  for  many  papers  by  different  authors. 

For  descriptions  of  the  Reptiles  see  Hitchcock,  loc.  cit. ;  Emmons,  loc.  cit. ;  Wyman, 
Am.  Jour.  Sc.,  1855;  Leidy's  papers  in  the  publications  of  Acad.  Nat.  Sc.  Philad.,  1854 

1186. 


Fig.  1186,  Myrmecobius  fasciatus  (x  |). 

find  its  nearest  living  analogue  in  Myrmecobius,  for  each  ramus  of  the  lower  jaw  contained  ten 
molars  (premolars  included)  in  a  continuous  series,  one  canine  and  three  conical  incisors,  — the 
latter  being  divided  by  short  intervals." 


756  HISTORICAL   GEOLOGY. 

and  later;  Marsh,  in  Am.  Jour.  8c.,  since  1875 ;  Cope  in  publications  of  Acad.  Nat.  Sc. 
Philad.,  Amer.  Phil.  Soc.  and  Amer.  Naturalist,  since  1864. 

On  Fossil  Fishes,  John  H.  Redfield,  Ann.  N.  Y.  Lye.  N.  Hist.,  1836  ;  William  C.  Redfield,. 
Am.  Jour.  Sc.,  1838  to  1843  ;  Newberry,  U.  S.  G.  S.,  4to,  1888,  with  figures  of  the  species. 

On  the  Mammals,  E.  Emmons,  loc.  cit. ;  H.  F.  Osborn,  Acad.  Nat.  Sc.  Philad.,  4to,. 
1888,  and  also  in  later  papers  ;  R.  Owen,  Pal.  Soc.  London,  1871. 


2.   Triassic  and  Jurassic  of  the  Western  Interior  and  Pacific  Border  Regions, 

Triassic  Formation. 

The  Trias  of  the  Western  Interior  and  Pacific  border  regions,  although 
of  great  thickness,  has  afforded  few  organic  relics  of  any  kind. 

PLANTS.  —  The  following  are  figures  of  three  species  of  Cycads  from  the 
Upper  Triassic  (B/hsetic)  of  Honduras,  described  by  Newberry  (1888).  At 
the  Abiquiu  Copper  Mines,  New  Mexico,  Newberry  obtained  (San  Juan  Eep.) 
the  new  species  Otozamites  Macombii  (also  from  Sonora),  and  Zamites 

1187 

1189 


CYCADS. —  Fig.  Ils7,  Anoinozamiteselegans  ;  1188,  Otozamites  linguiformis  ;  1189,  Encephalartos  (?)  denticulatus. 

Newberry. 

occidentalis.  Sonora,  Mexico,  has  afforded  Newberry  species  of  Pecopteris 
(Oligocarpia) ,  Alethopteris,  Camptopteris,  Tceniopteris,  including  the  Virginia 
species  Tmniopteris  magnifolia  (T.  latior  Star),  and  also  a  Jeanpaullia, 
J.  radiata,  Nby.,  near  J.  Munsteriana  of  the  Richmond  basin. 

ANIMALS.  —  The  marine  species  of  Invertebrates  include  Brachiopods 
of  the  genera  Rhynchonella,  Spiriferina,  and  Terebratula ;  Lamellibranch 
Mollusks  of  the  genera  Pecten,  Lima,  Avicula,  Monotis,  Jlalobia,  Daonella, 
Posidonomya,  Corbula,  Myophoria,  and  others ;  and  Cephalopods  of  the  old 
genus  Orthoceras,  and  under  the  Ammonite  group,  of  the  genera  Sageceras 
(Figs.  1190,  a),  Trachyceras  (Figs.  1191,  a),  Arcestes,  Tropites,  which  are 
characteristic,  and  also  many  others. 

A  few  Insects  have  been  described  by  Scudder  from  Fairplay,  Col., 
which  are  supposed  to  be  Triassic.  All  but  one,  a  Hemipter,  are  of  the 


MESOZOIC   TIME TKIASSIC   AND   JURASSIC. 


757 


Cockroach  group  (Blattariae)  ;  and  out  of  the  17  species,  11  have  the  wings 
like  those  of  the  Paleozoic  species  as  to  transparency  and  nervures,  and 
belong  partly  to  described  genera,  while  six  are  Mesozoic  in  the  character  of 


1190. 


1191  a. 


AMMONITE  FAMILY.— Fig.  1190,  Sageceras  Haidingeri;  1190  a,  same  in  profile;  1191,  Trachyceras  Whitney! ; 
1191  a,  same,  showing  form  of  pockets.     Gabb. 

the  nervures,  and  in  having  the  fore  wings  more  or  less  opaque,  approach- 
ing thus  the  modern  kinds.  This  commingling  of  Paleozoic  and  Mesozoic 
types  leads  Scudder  to  the  conclusion  that  the  beds  are  Triassic,  although 
referred  by  Lesquereux,  on  the  ground  of  some  imperfectly  preserved  fossil 
leaves,  to  the  Permian. 

The  Trias  of  Idaho,  which  Hyatt  considers  the  lowest  yet  found  in  this  country, 
contains,  according  to  White  (1879),  Terebratula  augusta,  T.  semisimplex,  Aviculopecten 
Idahoensis  Meek,  A.  Pealsi,  A.  altus,  Eumicrotis  curta  Mk.  &  H.,  Arcestes  cirratus  (?), 
Meekoceras  aplanatum,  and  others. 

In  western  Nevada,  West  Humboldt  region  (King),  Orthoceras  Blakei,  Sageceras 
Haidingeri,  Trachyceras  Whitneyi,  Arcestes  Nevadensis  Mk.,  A.  Gabbi,  Myophoria  alta, 
Monotis  subcircularis,  Halobia  dubia,  Aoicula  Homfrayi,  Halobia  (Daonella}  Lommeli, 
Pecten  deformis,  Pentacrinus  asteriscus  (?),  etc.  Hyatt  reports  from  Desatoya  Moun- 
tains, New  Pass,  and  Walker's  Lake  of  Nevada,  besides  some  of  the  above  forms,  Gym- 
notoceras  rotelliforine,  Trachyceras  Whitneyi. 

In  the  Taylorville  region,  Plumas  County,  Cal.,  occur,  as  identified  by  Hyatt  (1829) 
from  the  successive  beds :  (a,  or  lowest)  slates,  the  Monotis  bed,  Monotis  subcircularis 
Gabb  (which  he  says  may  be  M.  salinaria  Schloth.),  Pecten  deformis  Gabb,  and  at  the 
top,  Daonella  tenuistriata  Hyatt ;  (&)  a  limestone,  the  Rhabdoceras  bed,  with,  besides  the 
preceding,  species  of  Nucula,  Lima,  Modiola,  Myacites,  Bhynchonella,  and  Ammonites  of 
the  genera  Ammonites  and  Arcestes,  Ehabdoceras  Eusselli  (a  strait  Ceratite),  with  Belem- 
nites  of  the  genus  Atractites ;  (c)  the  Halobia  bed,  with  species  of  Halobia,  Arcestes, 
Tropites  ;  (c?)  the  Hosselkus  limestone,  with  the  same  Ammonites,  and  others  of  the  genera 
Ceratites,  Badiotites,  and  Juvavites.  The  upper  subdivision  is  referred  by  Hyatt  to  the 
Lower  Carnic  of  the  Alpine  (Upper)  Trias,  and  the  others  to  the  Upper  Noric. 

From  British  Columbia  have  been  reported  by  Whiteaves,  who  has  described  several 
of  the  species  as  new  from  Queen  Charlotte  Islands,  the  Ammonites  Arcestes  Gabbi, 


758 


HISTORICAL   GEOLOGY. 


Badiotites  Carlottensis,  Aulacoceras  Carlottensis ;  from  northern  Vancouver,  Arcestes 
Gabbi  and  Arniotites  (Balatonites}  Vancouverensis  ;  from  Liard  Kiver,  about  59°  16'  N. 
and  125°  35'  W.,  Spirifer  borealis,  Terebratula  Liardensis,  Halobia  (Daonella)  Lommeli, 
H.  occidentalis,  Monotis  subcircularis  Gabb  (probably  =  Pseudomonotis  Ochotica  of  Keyser- 
ling),  Nautilus  Liardensis  (near  N.  Sibyllce  of  Spitzbergen),  and  Trachyceras  Canadense 
(1889).  All  are  of  the  Upper  Trias. 

Of  Fishes,  few  species  are  known. 

Several  Saurian  vertebrae  are  mentioned  by  King  as  having  been  observed  in  the 
Trias  of  western  Nevada,  and  Hyatt  speaks  of  fragments  of  Vertebrates  in  the  Sierra 
Nevada  Triassic.  A  large  Crocodilian  of  the  genus  JSelodon  has  been  described  by  Cope, 
from  the  Gallinas  valley  in  the  Sierra  Madre  Mountains,  New  Mexico,  under  the  name 
Typothorax  coccinarum.  Dystrophasus  vicemalce  Cope  (1877),  found  by  Newberry  in 
Painted  Cafion,  southeastern  Utah,  is  supposed  to  be  a  Dinosaur. 

Although  Amphibians  are  many  and  of  great  size  in  Europe  at  this  era,  no  remains 
are  yet  known  from  the  western  half  of  North  America. 

Jurassic  Formation. 

The  Jurassic  beds  are  much  less  barren  in  fossils  than  the  Triassic,  and 
yet  are  seldom  prolific  in  species.  Gastropods  are  rare,  and  Cephalopods 
not  numerous.  Invertebrate  species  were  first  discovered  in  them  by  Meek, 
at  the  Black  Hills,  where  the  species  here  figured  occur  along  with  many 
others.  The  Crinoid  disk,  Fig.  1192,  is  of  the  genus  Pentacrinus.  A  species 


1193. 


1192-1197. 


1194. 


1196  a. 


1196. 


Fig.  1192,  a  segment  of  the  column  of  Pentacrinus  asteriscus ;  1193,  Monotis  curta ;  1194,  Trigenia  Conradi ; 
1195,  Tancredia  Warreniana ;  1196,  Quenstedioceras  cordiforme ;  1196  a,  side  view  of  same,  a  little  reduced  ; 
1197,  Belemnites  densus.  Meek. 

of  the  Ammonite  group  is  represented  in  Figs.  1196, 1196  a.  The  Belemnite, 
Belemnites  densus  Meek,  Fig.  1197,  is  from  these  beds,  which  have  been 
named  by  Marsh  the  Baptanodon  beds.  (These  Baptanodon  beds,  near 
Como,  Colorado,  are  marine,  and  overlie  Red  beds  which  are  referred  to  the 
Triassic;  above  them  are  the  freshwater  Atlantosaurus  beds  of  Marsh,  and 
overlying  these  comes  the  Dakota  group.)  The  fossil  here  represented  is 
the  lower  end  of  the  internal  bone  answering  to  the  bone  of  the  Squid,  but 
differing  from  those  of  modern  species  in  the  texture  and  weight  of  the 


MESOZOIC    TIME  —  TRIASSIC   AND   JURASSIC. 


759 


posterior  portion  or  "  guard."     (A  perfect  bone  of  similar  nature  is  shown  in 
Fig.  1300,  page  782.) 

The  Jurassic  of  Taylorville,  Plumas  County,  Cal.,  has  afforded  Hyatt 
many  species,  and  among  them,  from  the  Upper  Lias,  Pinna  expansa.  Fig. 
1201 ;  from  the  Oolyte,  Lima  Taylorensis,  1199,  and  Entolium  gibbosum,  1200 ; 
and  from  thfe  Coral  bed,  Stylina  tubulifera,  1202.  The  Ammonite,  Arnioceras 
Nevaduum  (Fig.  1198)  is  from  the  Jurassic  at  Volcano,  Nev.  (Am.  Jour. 
Conch.,  vol.  v.,  pi.  3). 


1198-1202. 


1198. 


Fig.  1198,  Arnioceras  Xevaduum ;  1199,  Lima  Taylorensis;  1200,  Entolium  gibbosum ;  1201,  Pinna  expansa; 

1202,  Stylina  tubulifera.     Original. 

Shells  of  the  species  of  Aucella  from  the  Auriferous  slates  are  repre- 
sented in  Figs.  1203-1205.  Aucella  Erringtoni  (so  named  in  commemoration 
of  the  first  discoverer  of  fossils  on  the  Mariposa  estate,  Miss  Errington) 
occurs  in  the  partially  metamorphic  upturned  slates ;  Fig.  1203  represents 
the  common  form ;  and  1204,  a  narrower  variety  occurring  in  the  sandstone. 
The  Trias  sic  genus  Monotis  is  continued,  one  species  of  which  is  shown  in 


1203 


1208-1205. 
1204 


1205 


MOLLTTSK.  —  Aucella  Erringtoni.    Meek. 


Fig.  1193.  Trigonia,  related  to  Myophoria,  has  its  first  American  species. 
Other  characteristic  genera  of  Lamellibranchs  are  Tancredia,  Lima,  Gervillia, 
Gryphceaj  Inoceramus,  and  Pholadomya. 


760  HISTORICAL  GEOLOGY. 

The  Jurassic  of  Dakota,  Wyoming,  and  Utah  have  afforded  Ostrea  stringilecula, 
Tancredia  extensa,  Camptonectes  bellistriatus,  and  the  Ammonite  Quenstedioceras  cordi- 
forme.  That  of  Idaho  afforded  White :  Pentacrinus  asteriscus,  Ostrea  stringilecula, 
species  of  Tancredia,  Trigonia,  Myacites,  etc.  In  the  Uintah  Mountains,  where  the 
rocks  are  shales  and  sandstones  with  limestone,  occur  Pentacrinus  asteriscus,  Belem- 
nites  densus,  Trigonia,  Gryphcea  calceola,  Myophoria  lineata,  Camptonectes  bellistriatus, 
Eumicrotis  curta,  etc. ;  and  in  the  Wasatch  have  been  found  Cucullcea  Haguei,  Myophoria 
lineata,  Myacites  subcompressa,  Volsella  scalpra  (King's  Report  on  the  40th  Parallel). 

In  the  West  Humboldt  region,  west  Nevada,  occur  Belemnites  Nevadensis,  species  of 
Montlivaltia,  etc.;  and  probably  from  this  region  came  the  Ammonite,  Arnioceras 
JIumboldti;  in  Esmeralda  County,  Nev.,  Vermiceras  Crossmani,  Arnioceras  Nevadense; 
in  Inyo  County,  Cal.,  Arnioceras  Woodhulli. 

Jurassic  beds  at  Taylorville,  Cal.,  on  the  Sierra  Nevada,  afforded  Hyatt,  in  the  lower 
toeds  referred  to  the  Lias,  besides  the  most  of  the  above  genera,  species  of  Pinna, 
Entolium,  Goniomya,  Pleuromya;  also  an  Echinoderm  of  the  genus  Cidaris  and  a 
Crustacean  of  the  genus  Glyphcea.  The  Middle  Oolytic  beds  contain,  among  the  species, 
Ammonites  of  the  genera  Grammoceras  and  Sphceroceras  ;  and  the  Upper  Oolyte,  species 
of  the  genus  Rhacophyllites,  with  3  species  of  Trigonia  in  the  lower  bed  referred  to  the 
Callovian  division  of  the  Oolyte,  and  several  species  of  Coral  of  the  genus  Stylina  referred 
to  the  Corallian,  besides  the  Camptonectes  bellistriatus  Mk.,and  the  Rhacophyllites  of  the 
Upper  Oolyte.  Hyatt  speaks  of  the  contrast  of  the  species  with  those  of  the  summit  region 
of  the  Black  Hills,  southeastern  Wyoming,  whose  Ammonites  are  of  the  Cardioceras 
family  and  whose  beds  are  Callovian  or  Oxfordian. 

The  Mariposa  beds  extending  to  near  Coif  ax,  Placer  County,  Cal.,  contain,  according 
to  Hyatt,  Cardioceras  dubium  of  Oxfordian  age,  and  striated  Aucellce  (Figs.  1203-1205)  in 
great  numbers,  Perisphinctes  of  the  same  types  as  those  found  in  the  Upper  Jura,  Upper 
Oxfordian,  and  Volgian  of  Russia,  namely,  Perisphinctes  virgulatiformis,  P.  Colfaxi, 
P.  Muhlbachi,  and  Belemnites  Pacificus.  None  of  these  species  pass  into  the  Knoxville 
beds. 

The  Queen  Charlotte  beds  have  afforded  Whiteaves  (Mesozoic  Foss.,  Can.  Survey, 
1884)  species  of  the  Ammonite  group  of  the  genera  Lytoceras,  Haploceras,  Ancyloceras 
{A.  Eemondi  of  Gabb),  Hamites,  and  also  species  of  Trigonia,  Inoceramus,  Aucella, 
Amusium,  Yoldia,  etc.;  also  Belemnites  densus. 

Among  the  Arctic  fossils  of  this  period,  there  are,  at  Prince  Patrick  Island,  Ammo- 
nites M'Clintocki,  a  species  near  A.  concavus  Sow.,  of  the  Lower  Oolyte;  and  at  Cook's 
Inlet,  Ammonites  Wosnessenski,  A.  biplex  Sow.  (?),  Belemnites  paxillosus  (B.  niger  List  ?), 
and  Pleuromya  unioides  Br.  (TJnio  liassinus  Schubler).  A.  biplex  also  is  reported  to 
occur  in  the  Chilean  Andes,  in  latitude  34°  S.,  as  well  as  in  Britain  and  Europe. 

1.  Fishes.  —  Fishes  are  rare  fossils.     The  teeth  of  Ceratodus  Gilntheri  of 
Marsh  have  been  described  from  the  Upper  Jurassic  (Atlantosaurus  beds) 
of  Colorado. 

2.  Reptiles.  —  The  Upper  Jurassic  formation  of  Colorado  and  Wyoming  has 
afforded  remains  of  a  few  Amphibians,  many  great  and  small  Beptiles,  and 
of  some  Mammals.     The  specimens  are  thus  far  from  the  "  Baptanodon  and 
Atlantosaurus  beds  "  of  Colorado  and  Wyoming.     They  include  Sea-Saurians 
related  to  the  Ichthyosaurs  (page  784),  and  also  Dinosaurs,  Crocodilians, 
Turtles,  and  Pterosaurs  or  Flying  Keptiles. 

Enaliosaurians  (Ichthyopterygians).  —  These  Sea-Saurians  are  the  most 
fish-like  of  Eeptiles.  This  appears  (1)  in  their  biconcave  vertebrae  (Fig. 


MESOZOIC   TIME — TRIASSIC   AND   JURASSIC. 


761 


000%° 

00 

O0o°° 


o0 


Fig.  1206,  Baptanodon  discus,  left  hind  paddle  (x  £);  /,  femur  ;  t  and  m, 
bones  answering  to  tibia  and  fibula;  I,  first  digit;  V,  fifth  digit. 
Marsh. 


1315  a,  page  784);  (2)  in  their  locomotive  organs  or  paddles  (Fig.  1206)  which 
are  fin-like  in  having  no  defined  limb-bones  beyond  the  upper,  the  rest  of  the 
limb  being  represented  12Q6 

by  several  series  of 
bones,  and  the  number 
of  series  exceeding  the 
normal  number  of  fin- 
gers, five ;  and  (3)  in 
the  absence  of  a  breast 
bone,  and  the  presence 
of  dorsal  fins.  The 
specimens  from  Wyo- 
ming of  Baptanodon 
discus  of  Marsh  indi- 
cate a  species  eight  or 

nine  feet  in  length,  with  a  toothless  head  and  the  orbit  of  great  size  (as  in 
Ichthyosaurs,  page  784),  with  a  sclerotic  ring  of  8  plates,  which  is  conical  as 
in  some  birds. 

Dinosaurs.  —  Localities  in  Colorado  and  Wyoming  are  the  most  important 
source  of  what  is  known  about  Jurassic  Dinosaurs.  They  were  the  most 
gigantic  of  terrestrial  animals,  in  some  cases  reaching  a  length  of  70  or  80  feet, 
while  at  the  same  time  they  had  a  height  of  body  and  massiveness  of  limb  that, 
without  evidence  from  the  bones,  would  have  been  thought  too  great  for 
muscle  to  move.  Besides  this,  some  of  the  huge  beasts  had  the  most 
diminutive  of  brains;  but,  as  a  compensation,  a  nervous  mass  in  the 
sacrum  20  to  30  times  as  large  as  the  brain  for  use  in  connection  with  the 
hinder  limbs  and  tail.  There  were  both  Carnivorous  and  Herbivorous  kinds, 
the  latter  the  inferior. 

The  American  Herbivorous  species  are  of  three  groups :  (a)  The 
Sauropods  or  Saurian-footed ;  kinds  having  the  fore  and  hind  limbs  nearly 
equal,  crocodile-like,  with  all  the  feet  five-toed  (that  is,  with  five  usable 
toes);  the  limb  bones  solid,  but  the  vertebrae,  especially  the  anterior, 
cavernous,  and  thereby  light,  (b)  The  Stegosaurians,  having  very  short 
fore  limbs ;  the  fore  feet  five-toed  and  hinder  three-toed ;  the  limb  bones  and 
vertebrae  solid;  and  the  body  covered  with  bony  pieces  or  plates;  the 
vertebrae  all  biconcave,  (c)  The  Ornithopoda  or  bird-footed,  having  very 
short  fore  limbs  with  the  long  hind  limbs  three-toed,  bird-like,  rarely  four- 
toed  ;  the  bones  of  the  hind  limbs  hollow,  but  the  vertebrae  solid.  (Marsh.) 

The  Carnivorous  species  have  in  all  cases  the  fore  limbs  short  compared 
with  the  hind  limbs,  and  the  latter  usually  three-toed,  bird-like.  The  limb 
bones  are  hollow,  and  the  vertebrae  are  more  or  less  cavernous,  in  order,  as 
in  birds,  to  have  less  to  lift,  especially  in  the  anterior  part  of  the  body. 

The  following  are  some  examples  of  Jurassic  species  under  the  several 
subdivisions.  The  specimens  are  all  from  the  Atlantosaurus  beds  of  Colorado 
and  Wyoming. 


762 


HISTORICAL   GEOLOGY. 


(1)  Herbivorous  Dinosaurs.  —  (a)  Sauropods.  An  idea  of  the  skull  in  this 
group  is  afforded  by  the  following  figures  of  Diplodocus  longus  Marsh,  found 
near  Canon  City.  The  length  of  skull  in  this  species  was  about  21  inches;  of 


1207. 


1208. 


I    e 


Fig.  1207,  Diplodocus  longus,  skull,  side  view  (x £);  1208,  id.  upper  view  (x  J);  o,  aperture  in  maxillary  ;  &,  antorbi- 
tal  opening;  c,  nasal  opening;  c',  cerebral  hemispheres;  d,  orbit;  e,  lower  temporal  fossa;  /,  frontal 
bone  ; /*,  fontanelle ;  TO,  maxillary  bone;  m',  medulla;  n,  nasal  bone;  oc,  occipital  condyle ;  oZ,  olfactory 
lobes  ;  op,  optic  lobe  ;  p,  parietal  bone  ;  pf,  pre-frontal  bone  ;  pm,  pre-maxillary  bone  ;  q,  quadrate  bone ; 
qj,  quadrato-jugal  bone.  Marsh. 

brain,  about  three  inches ;  of  body,  50  feet.  The  position  and  relative  size  of 
the  brain  is  shown  in  Fig.  1208  at  c'.  The  teeth  were  peculiar,  being  very 
slender  and  long,  and  confined  to  the  terminal  part  of  the  jaws.  The 
animal  is  supposed  to  have  been  a  hippopotamus-like  wader,  and  to  have 
lived  on  vegetation  in  the  waters. 


MESOZOIC   TIME — TBIASSIC   AND  JUKASSIC. 


763 


1209-1211. 


1210. 


1209. 


The  general  character  of  the  limbs,  their  height  and  massiveness,  and  the 
form  of  the  pelvic  bones,  are  exhibited  in  Figs.  1209-1211  of  Morosaurus 
grandis  Marsh,  a  species 
about  40  feet  long.  The 
femur  (/)  is  about  four 
feet  in  length.  The 

teeth  (Fig.  1211,  half  the  ^      J  ^  1211. 

natural  size)  are  shorter 
than  in  the  preceding 
species,  and  more  numer- 
ous. Nearly  complete 
skeletons  of  this  Moro- 
saurus have  been  ob- 
tained by  Marsh  in 
Wyoming. 

Fig.  1212  represents 
a  restoration  of  an 
allied  species,  the 
Brontosaurus  excelsus 
Marsh,  of  which  also  a 
skeleton  nearly  complete 

has  been  obtained.      The     DINOSATTK.  —  Morosaurus  grandis  (x^).    Fig.  1209,  fore  leg  ;  s,  scapula ; 


total  length  is  about  60 

feet,  and  the  height  of 

the     skeleton     at     the 

middle  of  the  body  about 

15  feet,  showing  great  magnitude ;   and  yet  it  had,  relatively  to  size  of  body, 

one  of  the  smallest  of  heads  known  among  vertebrates.     Like  Morosaurus, 


c,  coracoid ;  h,  humerus  ;  r,  radius  ;  u,  ulna  ;  uc,  ulnar  carpal ;  I, 
first  metacarpal;  Vmc,  fifth  metacarpal.  Fig.  1210,  hind  leg;  il, 
illiac ;  is,  ischium  ;  p,  pubis ;  /,  femur ;  t,  tibia ;  /',  fibula ;  a, 
astragalus;  c,  calcaneum ;  Vmtf,  fifth  metatarsal.  Fig.  1211,  tooth 
(xj).  From  Marsh. 


1212. 


Fig.  1212,  Brontosaurus  excelsus,  restoration  (x  x&y).     Marsh. 


its  vertebrae  were  very  light  and  cavernous,  with  thin  walls,  even  in  the  axis( 
of  the  sacrum.     The  feet  were  large  enough  to  make  tracks  a  square  yard 
in  area.     The  sixth  cervical  vertebra  was  over  25  inches  high  and  21  broad. 
The  size  of  neck  was  still  greater  in  another  species,  Apatosaurus  laticollis 


764 


HISTORICAL   GEOLOGY. 


1213. 


Marsh,  the  corresponding  dimensions  of  a  cervical  vertebra  (Fig.  1213)  being 
4  feet  and  2^  feet.  In  Atlantosaurus  immanis  Marsh,  a  species  probably  70 
or  80  feet  long,  the  femur  was  over  six  feet  in  length. 

(b)  Stegosaurians.    The  Stegosaurs  of  Marsh  were  other  huge  species,  but 

with  the  fore  limbs  much  the  shorter,  and 
all  the  bones  solid.  They  were  remarkable 
for  the  crest  of  great  bony  plates  along  the 
back,  the  diminutive  size  of  the  brain,  and 
the  enormous  supplementary  nervous  mass 
in  the  sacrum.  The  figure  is  the  restora- 
tion of  Stegosaurus  ungulatus  Marsh,  by  the 
describer,  -fa  the  natural  size.  The  head 
had  a  horny  beak.  The  throat  was  covered 
with  small  ossicles.  The  larger  of  the 
plates  along  the  back  were  1^  feet  broad ; 
and  the  spines  along  the  caudal  portion, 
nearly  2  feet  long.  All  the  plates  and 
spines  had  originally  a  thick  horny  cover- 
ing. The  relative  size  of  the  brain  and  the  nervous  mass  in  the  sacrum  is 
shown  in  the  figures,  of  J  natural  size :  Fig.  1215,  the  brain ;  1216,  the  mass 
in  the  sacrum. 

1214. 


1214  a. 


Fig.  1218,  Apatosaurus  .  laticollis,  cervical 
vertebra  (x  &)  •  c,  concave  posterior 
articular  surface  ;  d,  diapophysis  ;  p,  para- 
popysis ;  h,  hatchet  bone,  or  anchylosed 
rib  ;  z',  postzygapophysis.  Marsh. 


Fig.  1214,  restoration  of  Stegosaurus  ungulatus  (x  ^5)  ;  1214  a,  tooth  of  same  (x  2).    Marsh. 

(c)  Ornithopoda.  —  The  animals  of  this  group  of  Herbivorous  Dinosaurs 
were  bird-like  in  feet,  and  strikingly  so  in  the  pelvic  bones.  Both  of  these 
characters  are  shown  in  the  restoration  of  Camptosaurus  dispar  of  Marsh 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC. 


765 


(Fig.  1217),  in  which  the  skeleton  is  reduced  to 
pare  with  Fig.  1423,  page  850.) 
Fig.  1219  represents  the  hind  leg 
of  an  allied  species,  Laosaurus  con- 
sors  of  Marsh,  and  1219  a,  a  tooth. 
Nanosaurus  agilis  Marsh  (Fig.  1220), 
from  Colorado,  is  the  smallest  of 
known  Dinosaurs,  being  about  as 
large  as  a  partridge.  Another  spe- 
cies, Nanosaurus  Hex  Marsh,  also 
from  Colorado,  was  not  larger  than 
a  Fox. 

(2)  Carnivorous  Dinosaurs.  —  Fig. 
1221  represents  a  restoration  of  Cera- 
tosaurus  nasicornis  Marsh,  a  mod- 
erately large  species  related  in 
general  characters  to  the  Megalosau- 
rus  of  Europe.  The  name  nasicornis 
alludes  to  their  having  a  horncore 
(h  in  Fig.  1222)  on  the  nose.  Owing 
to  the  form  of  the  pelvis,  the  body 
was  keeled  beneath ;  and  the  exist- 
ence of  such  a  keel  in  some  Triassic 
species  is  supposed  to  account  for 
an  impression  sometimes  found  in 
the  sandstone  between  pairs  of  footprints. 


the  natural  size.     (Com- 


1215-1216. 

1216. 


CTt- 


Fig.  1215,  cast  of  brain  of  Stegosaurus  (x  |);  ol,  olfac- 
tory nerves ;  op,  optic  lobes ;  on,  optic  nerve ; 
c6,  cerebellum  ;  ra,  medulla  oblongata.  Fig.  1216, 
cast  of  cavity  of  nervous  mass  in  the  sacrum, 
seen  from  above  (x  \)  •  f,f',f",  each  foramen 
between  two  sacral  vertebrae.  Marsh. 


1217 


1217-1220. 


1219 


HERBIVOROUS  DINOSAURS.  —  Fig.  1217,  restoration  of  Camptosaurus  dispar  (x  ^,)  ;  1218,  tooth  of  C.  medius; 
1219,  Laosaurus  censors,  hind  leg  (x  Ty) ;  1219  a,  tooth  of  same;  1220,  Nanosaurus  agilis,  dentary  bone,  as 
seen  from  the  left,  natural  size.  All  from  Marsh. 


766 


HISTORICAL   GEOLOGY. 


1221. 


1222. 


DINOSAUR.  —  Fig.  1221,  Restoration  of  Ceratosaurus  nasicornis  (x  ,fo) ;  1222,  skull  of  same  (x  ft)  ;  h,  horncore. 

Marsh. 

Allosaurus  Marsh  is  another  genus  of  Carnivorous  Dinosaurs  from  the 
Atlantosaurus  beds,  near  Megalosaurus  in  its  characters.  Labrosaurus  of 
Marsh  is  another. 


1223. 


1224. 


TURTLES.  —  Fig.  1223,  Glyptops,  a  Turtle  skull,  natural  size;  1224,  carapace  of  probably  the  same  species  (x  |). 

Marsh. 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC. 


767 


Testudinates.  —  Glyptops  ornatus  Marsh  (1890)  was  a  Turtle  with  an 
-elaborately  sculptured  skull,  from  the  freshwater  Atlantosaurus  beds  of 
Wyoming.  The  form  of  the  skull  is  shown  in  Fig.  1223.  The  carapace 
represented  in  Fig.  1224  was  found  in  the  same  beds,  and  is  probably  of 
the  same,  or  an  allied,  species. 

A  tortoise  over  a  foot  in  diameter  has  been  described  by  Cope  (1878), 
under  the  name  Compsemys  plicatulus,  from  the  Upper  Jurassic  beds  of  Coino, 
Wyoming.  The  bony  case  or  carapace  is  as  complete,  according  to  Cope,  as 
in  a  modern  tortoise,  being  without  any  embryonic  or  transitional  characters. 

Pterosaurs,  or  flying  Reptiles  (Figs.  1321  to  1325,  pages  786, 787),  are  known 
from  a  few  bones  from  Wyoming.  The  character  of  the  wing  in  the  Ptero- 
saurs is  shown  in  Fig.  1321.  The  type  specimen  of  Pterodactylus  montanus 
Marsh  is  the  distal  portion  of  the  metacarpal  bone.  The  size  indicates  a 
spread  of  wing  of  four  or  five  feet. 

3.  Birds.  —  A  portion  of  a  skull  of  a  bird  rather  larger  than  a  Blue 
Heron  (Ardea  herodias),  from  the  Atlantosaurus  beds  of  Wyoming,  is  the 


12-25 


1226 


1225-1249. 


1230 


MAMMALS.— Fig.  1225,  Allodon  laticeps,  upper  jaw,  view  from  below;  1226,  A.  fortis,  right  premaxillary,  outer 
view  ;  1227,  id.,  inner  view ;  1228,  id.,  lower  incisor ;  1229,  id.,  left  upper  jaw ;  1230,  Otenacodon  serratus, 
right  lower  jaw ;  1231,  id.,  left  lower  jaw ;  1232,  C.  potens,  left  lower  jaw ;  1233,  front  view,  showing  the  two 
long  incisors  together ;  1234,  id.,  right  upper  jaw ;  1235,  Stylacodon  gracilis,  left  lower  jaw ;  1236,  Dryolestea 
priscus,  left  lower  jaw ;  1237,  D.  vorax,  left  lower  jaw ;  1238,  Laodon  venustus,  left,  inner  view ;  1239,  Asthe- 
nodon  segnis,  right,  outer  view ;  1240,  id.,  anterior  part  left  lower  jaw ;  1241,  Tinodon  bellus,  right,  inner 
view  ;  1242,  Diplocynodon  victor,  outer  view ;  1243,  Docodon  striatus,  inner ;  1244,  Menacodon  rarus,  outer 
view ;  1245,  id.,  inner  ;  1246,  Enneodon  crassus,  outer  view ;  1247,  Priacodon  ferox,  inner  view ;  1248,  1249, 
Paurodon  valens,  left  lower  jaw.  All  natural  size  except  1225,  1230,  1238,  which  are  | ;  and  1242,  1243,  f. 
From  Marsh. 


768  HISTORICAL   GEOLOGY. 

basis  of  the  species  Laopteryx  prisons  of  Marsh.     It  probably  had  teeth  and 
biconcave  vertebrae. 

4.  Mammals.  —  Remains  of  Jurassic  Mammals  have  been  described  by 
Marsh  from  the  Atlantosaurus  series,  and  mostly  from  Wyoming,  where 
portions  of  lower  jaws  of  some  hundreds  of  individuals  have  been  found 
in  thin  dirt-beds.  (The  same  beds  have  afforded,  besides  Dinosauriau  bones, 
remains  of  Crocodiles,  Turtles,  small  Lizards,  and  Fishes,  besides  the  Laop- 
teryx.) The  Mammals  were  like  mice  and  rats  in  size,  the  length  of  the 
lower  jaw  varying  from  half  an  inch  to  one  and  one  half  inches.  Specimens, 
more  or  less  perfect,  of  the  jaws  of  species  are  shown  in  Figs.  1225-1249, 
from  Marsh.  Ctenacodon  has  a  large  cutting  incisor,  as  Figs.  1230-1233 
show,  and  is  referred,  along  with  the  genus  Allodon,  to  the  same  family  with 
the  genus  Plagiaulax  of  Owen.  The  characters  of  the  others  are  mostly 
those  of  Marsupial  Insectivores.  The  number  of  teeth  in  some  modern 
Marsupials  is  2  to  4  above  the  normal  number  44 ;  but  in  the  Triassic  and 
Jurassic  species,  where  determinable,  as  tabulated  by  Osborn,  it  is  beyond  the 
normal  number  by  4  to  24  teeth ;  the  earliest  Dromatherium  is  stated  to  have 
had  56  teeth ;  the  Jurassic  Stylacodon,  68. 

FOREIGN   TRIASSIC   AND   JURASSIC. 

1.  TRIASSIC. 

At  the  commencement  of  the  Triassic  period,  Scotland  and  western 
England  were  mostly  dry  land.  Triassic  beds  show  that  the  only  under- 
water or  rock-making  region  of  western  England  (Wales  included)  was 
that  of  a  broad  channel,  passing  westward  over  Cheshire  to  the  coast  of 
the  Irish  Sea  by  Liverpool,  and  northward  of  that  city.  Eastward,  the  chan- 
nel opened  into  the  North  Sea  of  the  era,  or  into  its  great  sea-border  flats ;. 
and  the  shore  line  stretched  northward  nearly  to  Newcastle,  thence 
along  by  eastern  Scotland,  and  southwestward  to  Torquay  on  the  British 
Channel.  But  the  seashore  flats  appear  to  have  been  emerged  land  over 
southeastern  England,  the  Triassic  being  absent  according  to  evidence  from 
borings.  In  Europe,  southeast  of  England,  beyond  a  broad  border  region  of 
the  continent  (now  under  Tertiary  or  Cretaceous  rocks),  Triassic  beds  again 
appear  over  both  eastern  France  and  the  Netherlands ;  and  the  two  areas, 
united  (beneath  a  strip  of  Tertiary)  behind  the  Carboniferous  area  of  the 
Belgian  border,  continue  from  the  Vosges  Mountains  to  Saxony,  Bohemia, 
and  the  Juras  on  the  borders  of  Switzerland,  and  also  along  the  western  and 
eastern  Alps  into  Italy  and  Austria.  Further,  they  appear  again  over  a 
large  surface  in  Russia,  west  of  the  Urals,  reaching  from  the  Caspian  to  the 
coast  east  of  the  White  Sea,  and  again  farther  north,  in  Spitzbergen,  as 
already  stated.  And  since  the  interval  between  the  Triassic  outcrops  of 
Austria  and  Eussia,  and  that  between  the  Alpine  and  the  Franco-Prussian 
areas  are  largely  under  later  rocks,  it  is  probable  that  at  this  period  nearly 
all  outside  of  Scandinavia  and  the  Baltic  provinces  in  Russia  was  a  shallow 


MESOZOIC   TIME  —  TEIASSIC   AND   JURASSIC.  769 

continental  sea.  In  the  earlier  and  later  part  of  the  Triassic,  it  was  very 
shallow,  the  conditions  those  of  sea  margins  and  seashore  basins,  and  brack- 
ish-water flats  ;  in  its  middle  portion  of  somewhat  deeper  waters ;  but  about 
the  region  of  the  eastern  Alps,  and  along  the  side  of  the  Alps  toward  the 
Mediterranean,  as  well  as  in  southern  France  and  Austria,  the  waters,  judg- 
ing from  the  prevalence  of  limestones,  their  thickness  and  the  fossils,  were 
those  of  a  clear,  open  sea.  This  region  has  been  designated  the  Mediterra- 
nean region. 

ROCKS  — SUBDIVISIONS,  KINDS  AND  DISTRIBUTION. 

1.  LOWER    TRIAS    or    VOSGIAN. —  Represented    generally    by    red    or 
variegated  sandstones  passing  to  whitish  marlytes  and  pebbly   beds;    salt 
beds  are  sometimes  present,  and  also  gypsum.     In  England  it  includes  the 
Lower  Red  Sandstone  of  the  Trias,  1000  feet  to  2000  feet  thick ;  in  Germany, 
the  Bimtersandstein ;  in  France,  the  Gres  des  Vosges  and  Gres  bigarre  (bunter 
and  bigarre  meaning  variegated)-,  but  in  the  eastern  Alps,  in  Lombardy,  and 
the  Tyrol,  a  limestone,  the  Gutenstein,  underlying  the  Werfen   sandstone 
with  rock  salt  and  gypsum. 

2.  MIDDLE  TRIAS  or  FRANCONIAN. —  The  rock  is  limestone  in  Germany, 
France,  and  the  Alps ;  it  is  not  recognized  in  England.     It  is  represented  by 
the  Muschelkalk  of  Germany,  with  the  Wellenkalk  below,  and  affords  rock 
salt  in  Wurtemberg ;  and  by  the  Calcaire  Conchy  lien  in  France. 

3.  UPPER  TRIAS.  —  (1)  Keuperian.     In  England  mostly  like  the  Lower 
Trias  in  its  rocks ;   it  affords  rock  salt  at  Cheshire.      In  Germany   there 
are,  below,  red   shales  and  marlytes   with  thin  coal  seams  —  the  Kohlen- 
keuper  or  Lettenkohle ;  and  above,  the  Keupermergel,  marlytes  containing 
gypsum.     Gypsiferous   beds  and  rock  salt  occur  in  Lorraine,  and  at   Salz- 
kammergut,  near  Salzburg,  Austria.     In  the  eastern  Alps,  there  are  the  St. 
Cassian  beds ;  in  Sweden,  gray  and  red  marlytes,  with  some  good  coal. 

(2)  The  Rhcetic,  so-named  from  the  Rhaetic  Alps.  The  beds  are  limestone 
or  shales.  They  include  the  Kossen  beds  of  Germany,  the  Avicula  contorta 
beds ;  the  larger  part  of  the  Dachstein  limestone  of  the  eastern  Alps ;  and 
in  England  the  Penarth  beds  of  shales  overlying  the  Trias  from  Yorkshire 
to  Lyme-Regis,  50  to  150  feet  thick.  One  to  three  bone-beds  occur  in  the 
lower  part  in  England,  and  also  in  Bourgogne,  Hanover,  Brunswick,  and 
Franconia.  The  Rhaetic  is  sometimes  placed  at  the  base  of  the  Lias. 

The  Trias  has  great  thickness  in  the  Alps,  especially  the  Italian,  it  being 
nearly  13,000  feet  along  a  belt  from  Bardonneche  (Savoy),  by  the  Mont 
Cenis  tunnel,  to  Modena.  This  great  thickness  is  owing  to  the  fact  that 
preparations  were  in  progress,  through  a  geosyndine  of  accumulation,  for  the 
Tertiary  mountain  making,  which  took  place  along  the  range  at  the  close  of 
the  Miocene. 

In  peninsular  India,  the  upper  part  of  the  Gondwana  series,  the  Panchet  group,  is 
Triassic;  it  is  without  marine  fossils.    Outside  of  the  peninsula,  Triassic  beds  occur  in 
DANA'S  MANUAL  —  49 


770  HISTORICAL   GEOLOGY. 

the  Salt  Range  of  the  Punjab ;  in  northern  Kashmir,  and  along  the  mountain  region  as 
far  as  Spiti  in  western  Tibet,  resting  on  Carboniferous  rocks,  where  the  succession  of 
beds  from  the  Lower  to  the  Upper  is  closely  like  that  of  the  Alps.  They  are  concealed  by 
Cretaceous  if  they  exist  in  Sind.  In  South  Africa,  the  Karoo  beds  include,  above  the  Ecca 
beds  (which  are  referred  to  the  Permian,  and  are  equivalents  of  the  Lower  Gondwana  of 
India)  :  (1)  the  Kimberley  shale ;  (2)  the  Beaufort  beds  ;  and  (3)  the  Stormberg  beds  or 
Upper  Karoo ;  and  the  last  have  afforded  Palceoniscus  Bainei,  P.  sculptus,  Ceratodus 
Capensis,  etc.  None  of  the  fossils  are  marine. 

In  Australia,  in  New  South  Wales,  the  widespread  Hawkesbury  sandstone,  mostly 
unfossiliferous,  is  probably  Jurassic  or  Jura-Trias.  In  New  Zealand,  Dr.  Hector  has 
described  as  Triassic  an  Qreti  series,  including  great  bowlder  deposits,  in  northern  and 
southern  New  Zealand,  containing  stones  up  to  5'  in  diameter ;  and  the  overlying  Wairoa 
series,  in  which  are  some  Upper  Triassic  fossils. 

For  further  details  as  to  subdivisions,  see  page  773. 


LIFE  OF  THE  FOREIGN  TRIASSIC. 

PLANTS. — The  range  of  Triassic  plants  corresponds  with,  that  of  North 
America.  Among  Conifers  occur  the  Cypress,  Figs.  1250,  1251,  Voltzia  hetero- 
phylla,  from  the  Lower  Trias,  and  Spruces  of  the  genus  Albertia.  Of  Cycads, 

1250-1252. 

1252 


Fig.  1250,  Voltzia  heterophylla ;  1251,  one  of  its  fruit-bearing  branches ;  1252,  Pterophyllum  Jsegeri.    Figs.  1250, 

1251,  from  Vogt ;  1252,  Bronn. 

Pterophyllum  Jcegeri,  Fig.  1252,  is  a  species  from  the  Upper  Trias.     Ferns 
and  Equiseta  were  common. 

ANIMALS.  —  1.  Radiates,  though  not  abundant,  are  represented  by  Cri- 
noids,  Starfishes,  and  a  few  Corals.  Among  Crinoids,  the  Middle  Trias 
(Muschelkalk)  affords  abundantly  the  Lily  Encrinite,  Encrinus  liliiformis, 
Fig.  1253.  The  Lamellibranch,  Gervillia  socialis,  Fig.  1254,  is  from  the  same 
limestone ;  the  Myophoria,  Fig.  1255,  of  the  Trigonia  family,  is  from  the 
Upper  Trias.  The  Avicula  contorta  Portl.,  characteristic  of  the  Ehaetic  beds, 
is  represented  in  Fig.  1256.  The  Cephalopods  were  represented  by  Ceratites, 
one  of  which,  from  the  Muschelkalk,  C.  nodosus  Schloth.,  is  shown  in  Figs. 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC. 


771 


1253. 


1253-1257. 


1258,  1259 ;  an  Ammonite,  from  the  Keuper,  is  the  Cladiscites  tornatus  Braun. 

The  genus  Choristoceras,  of  the  Ammonite  family,  contains  Triassic  species 

that  are  like  Ceratites 
1254.  in  the  partitions,  but 

the  whorls  of  the 
shell  are  not  con- 
tiguous,—  a  feature 
here  first  presented 
under  the  type  ;  and 
Cochloceras  of  the 
Trias  has  a  turreted 
shell  like  Turrilites 
of  the  Cretaceous. 

2.  Crustaceans, 
Insects.  —  Ostra- 
coids  are  common. 
Estheria  minuta 
Goldf.  (Fig.  1257) 
abounds  in  a  stra- 
tum of  the  Lower 
Trias,  and  has  given 
rise  to  the  name  Es- 
theria shales.  Macrurans,  allied  to  the  Crawfish  or  Lobsters,  occur,  one  of 
which  is  Pemphix  Sueurii  Desm.,  of  the  Muschelkalk  (Fig.  1262). 


CBINOID.  — Fig.  1253,  Encrinus  liliiformis.  LAMELLIBRANCHS.  —  Fig.  1254, 
Gervillia  socialis  ;  1255,  Myophoria  lineata ;  1256,  Avicula  contorta.  OSTRA- 
COID.  —  Fig.  1257,  Estheria  minuta.  Figs.  1253,  1257,  D'Orbigny  ;  1254, 
Vogt ;  1255,  Lyell ;  1256,  Portlock. 


1258-1261. 


1260. 


1262. 


CEPHALOPODS.  —Fig.  1258,  Ceratites  nodosus  ;  1259,  dorsal  view  of  portion  of 
same,  showing  the  dorsal  lobes  o/  the  septa ;  1260,  Cladiscites,  tornatus  ; 
1261,  side  view  of  same  (x£).  Figs.  1258,  1259,  D'Orbigny ;  1260,  1261, 
from  Vogt. 

Pemphix  Sueurii, 
from  Naumann. 

Insects  of  the  Trias  are  Cockroaches  (Orthopters)  of 

both  palseic  and  modern  type ;  several  true  Neuropters ;  and  Beetles  or 
Coleopters  of  the  Curculio  (Weevil)  family,  as  Curculionites  prodromus  Heer, 
and  of  Chrysomelids  and  Buprestids,  from  the  Lower  Keuper. 


772 


HISTORICAL   GEOLOGY. 


3.  Fishes.  —  Hybodont  and  Cestraciont  sharks  of  the  genera  Hybodus, 
Acrodus,  and  Strophodus  here  first  appear  :  Fig.  361,  a  tooth  of  Hybodus 
minor  Ag.,  from  the  Keuper,  and  Fig.  362,  of  H.  plicatilis  Ag.     There  were 
also  Ganoids  of  the  genera  Saurichtliys,  Gyrolepis,  Amblypterus,  Palceoniscus, 
Pycnodus,  etc. ;  and  Ceratodus  of  the  Dipnoans. 

4.  Amphibians. —  The  Labyrinth odont,  Mastodons aur us  giganteus,  was  a 
scale-covered  species ;  Fig.  1263  represents  its  cranium,  which  was  two  feet 
long,  and  Fig.  1263  a,  a  tooth  three  inches  long.     Several  other  species  of 
Labyrinthodonts  are  known  from  British  and  European  beds.     The  tracks, 
Fig.  1264,  named  Chirotherium  (from  x^p>  hand,  and  Orjpiov),  are  supposed  to 
be  those  of  a  Labyrinthodont. 


1263  a. 


1263. 


1263-1265. 


1265. 


1264. 


AMPHIBIANS.  —Fig.  1263,  Mastodonsaurus  giganteus  (x  &) ;  1263  a,  tooth  of  same ;  1264,  Chirotherium  (,x  T\,) ; 
1265,  track  of  a  Turtle  ?    Figs.  1263,  1263  a,  Braun  ;  1264,  1265,  D'Orbigny. 

5.  Reptiles.  —  The  British  and  other  foreign  Triassic  Keptiles  comprise 
species  of   Ehynchocephs,  Anomodonts,  Belodont  Crocodilians,  Dinosaurs, 

1266. 


RHYNCHOCEPH.  —  Fig.  1266,  Telerpeton  Elgiiiense.     From  .Maiiteli. 

Chelonians,  and   Sea-Saurians.     Under  the    Khynchocephs,  there   are   the 
genera:  Hyperodapedon  of  Huxley,  species  of  which  occur  in  the  Triassic 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC.  773 

beds  of  India,  as  well  as  Great  Britain ;  and  Rhynchosaurus,  from  the  Upper 
Trias  of  England,  both  having  the  jaws  beaked  at  the  extremity,  but  supplied 
with  short  palatal  teeth.  Telerpeton  Elginense  (Fig.  1266),  from  the  Elgin 
sandstones  of  Scotland  (at  first  supposed  to  be  Devonian  in  age),  is  referred 
to  the  Khynchocephs.  The  Anomodonts  include  Dicynodon  of  Owen,  and 
other  genera  from  the  Karoo  beds  of  South  Africa,  and  from  India;  also 
horned  Reptiles  from  Elgin,  one  of  which,  the  Elginia  mirabilis,  had,  besides 
a  pair  of  long  horns  in  the  position  of  those  in  cattle,  other  smaller  horn-like 
projections  over  the  front  and  sides  of  the  cranium.  The  Elgin  fauna  was 
closely  like  that  of  the  African  Karoo  beds,  and  the  Indian  Panchet  and 
Maleri  beds. 

Crocodilians  of  the  genus  Stagonolepis  occur  in  the  Upper  Trias  of  Eng- 
land and  Scotland,  and  a  Belodont  in  the  Rhsetic  beds  of  Germany.  The 
carnivorous  Dinosaurians  included  Thecodontosaurus  and  Palceosaurus  of  the 
Keuper. 

The  earliest  Sea-Saurians  are  from  the  Middle  Trias,  and  are  of  Plesio- 
saurian  type.     The  paddles  have  the  limb  bone   distinct  and  the  normal 
number  of  fingers  ;  the  teeth  are  in  sockets  ;  the  vertebrae  feebly  biconcave ; 
the  neck  very  long ;   the  orbits  very  large,  without  a  sclerotic 
ring.     The  Triassic  genera  Simosaurus,  Nothosaurus,  and  others,          1267. 
are   characterized   by  very  large  orbital  openings.     Both  of  the 
genera  Plesiosaurus  and  Ichthyosaurus  have  Rhsetic  species. 

Turtles  are  represented  in  the  Keuper  by  the  Proganochetys 
Quenstedtii  of  Baur.     The  tracks,  Fig.  1265,  are  supposed  to  be 
those  of  a  Turtle,  as  the  rights  and  lefts,  in  the  series  observed,        1267  a. 
are  far  apart. 

6.  Mammals.  —  The  earliest  remains  of  Mammals  are  found  in 
the  Rhsetic  beds ;  one  species  at  Wurtemberg  (Figs.  1267, 1267  a), 
Microlestes  antiquus  Plieninger,  and  another,  M.  Moorei  Owen, 
from  Somerset,  England.  The  teeth  resemble  those  of  Dromatherium.  The 
species  were  Marsupial.  Tritylodon  is  a  related  genus  from  the  Triassic  of 
South  Africa. 


Characteristic  Species. 

1.  Vosgian,  or  Lower  Trias  (in  the  Alps,  the  Werfenian).  — In  Germany,  the  upper 
part  contains,  with  sandstone,  some  limestone  or  dolomyte  and  gypsum,  with  Myophoria 
costata,  M.  vulgaris,  Naticella  costata,  Estheria  minuta,  Voltzia  heterophylla,  Equisetum 
arenaceum,    Chirotherium   (tracks),    Placodus,    Nothosaurus,     Trematosaurus.      Other 
Lower  Triassic  species  are  Ceratites  Middendorfi,  Triolites  Cassianus,  Kenodiscus  Schmidti, 
and  Dinarites  Liccanus. 

In  the  Alps  and  Mediterranean  province :    the  Werfen  shales ;  stage  of  Tirolanus 
Cassianus  and  Naticella  costata. 

2.  Franconian,  or  Middle  Trias.  —  In  Germany:  (a)  The  Wellen  Kalk  in  Franconia 
(Wurzburg,  etc.)  and  elsewhere,  with  Beneckia  Buchii  (Nautilus  bidorsatus),  Spirifer 

fragilis,  Gervillia  costata,  Gr.  socialis,  Myophoria  orbicularis ;   (&)    limestones,   partly 


774  HISTORICAL   GEOLOGY. 

oolytic,  with  Ceratites  nodosus,  Encrinus  liliiformis,  Myophoria  vulgaris,  Monotis  Alberti, 
Lima  striata,  Pecten  discites,  Spirifer  fragilis. 

In  the  Alps,  the  Virgloria  or  Gutenstein  limestone  (the  Virgloriari)  :  (a)  stage  of 
Trachyceras  balatonicum  and  T.  binodosum;  (6)  stage  of  Trachyceras  trinodosum.  In 
Lombardy  the  same  stages :  Varenna  marble,  Salvator  dolomyte,  Besano  dolomyte.  Other 
Middle  Triassic  species  are  Ptychites  gibbosus,  Gymnites  incultus,  Foosdiceras  bidorsatum, 
Atractites  secundus. 

3.  Upper  Trias.  —  (1)  Keuperian.  In  Germany:  (a)  Lettenkohle  group  with  the 
Grenzdolomit ;  Anoplophora  lettica,  Myophoria  Goldfussi,  Estheria  minuta,  Ceratodus, 
JEquiseta,  Calamites,  Voltzia ;  (6)  Keupermergel,  with  Anoplophora  Munsteri,  Estheria, 
Mastodonsaurus  Jcegeri,  Equiseta,  Pterophyllum  Jcegeri,  Calamites  arenaceus,  Danceopsis. 

In  the  Alps :  (a)  Wengen  shales  overlaid  by  (6)  the  St.  Cassian  beds  and  (c)  the 
Hallstadt  limestone  of  the  Salzburg  region  ;  (d)  Wetterstein  limestone  and  (e)  Schlern 
dolomyte ;  with  the  stages  (a)  Arcestes  giganto-galeatus  and  Pinacoceras  Metternichi 
(overlying  beds  of  the  Middle  Trias  containing  Choristoceras  Haueri) ;  (6)  Pinacoceras 
parma,  and  Didymites  globus ;  (c)  Arcestes  ruber ;  (dT)  Didymites  tectus  ;  (e)  Tropites 
subbullatus.  In  Lombardy :  the  zones  of  (a)  Trachyceras  Eeitzi  and  T.  Curionii;  (&)  T. 
Archelaus  and  Daonella  Lommeli. 

(2)  Mhcetic  beds.  — In  England  :  Avicula  contorta,  Pecten  Valoniensis  (these  two  species 
characteristic  and  abundant),  Pleurophorus  elongatus,  Pullastra  arenicola,  Monotis 
decussata,  Modiola  minima,  Ostrea  liassica;  Spirifer  Munsteri,  Estheria  minuta; 
Acrodus  minimus,  Hybodus  plicatilis,  Saurichthys  apicalis,  Gyrolepis  tenuistriata, 
vertebrse  of  Ichthyosaurs  and  Plesiosaurs,  tracks  of  Chirotherium ;  Microlestes  in 
Bone-bed.  Many  of  the  species  occur  also  in  the  Lias. 

In  the  Alps  :  (a)  Haibl  shales  ;  (6)  Hauptdolomit  (Dachstein  limestone);  (c)  Kossen 
beds :  stages  (a)  Trachyceras  aonoides,  Cardites  crenatus,  Germllia  bipartita ;  (6)  Turbo 
solitarius,  Avicula  exilis,  Megalodon  triqueter;  (c)  Avicula  contorta. 

The  "  White  Lias  "  of  England,  at  the  top  of  the  Khaetic,  also  called  the  Infra-Lias,  is 
the  Hettangian  of  Renevier. 

The  Triassic  rocks  of  Spitzbergen,  partly  bituminous  shales,  have  afforded  species  of 
Nautilus,  Ammonites,  Ceratites,  Halobia,  etc.,  closely  like,  if  not  identical  with,  species 
of  the  St.  Cassian  beds  (Laube). 

2.  JURASSIC. 

The  belt  of  Trias  in  England  (see  map,  page  694)  is  succeeded  on  the 
eastward  by  approximately  parallel  and  interlocking  belts  of  Lias  and 
Oolyte,  and  then  follows  the  Cretaceous.  This  position  of  the  Jurassic  areas 
between  the  Triassic  and  Cretaceous  is  common  over  Europe.  In  France  and 
Germany,  south  of  the  broad  coast  region  of  Tertiary  and  Cretaceous,  comes 
first  the  Jurassic  next  to  the  Cretaceous,  and  then  the  Triassic.  The  British 
Jurassic  belt,  which  reaches  the  Channel  at  Lyme-Regis,  reappears  in  France, 
and  is  continued  along  by  the  inner  side  of  the  Cretaceous,  about  the  so-called 
Paris  Basin,  and  also  in  Hanover,  in  northwestern  Germany.  Further, 
Jurassic  areas  border  the  inner  side  of  the  Triassic.  From  west-central 
France  they  extend  southeast  to  the  Mediterranean,  and  from  east-central 
southeast  to  the  Juras ;  and  a  long  Jura-mountain  belt,  of  northeastward 
course,  reaches  far  into  northern  Bavaria  and  Germany.  Jurassic  rocks  occur 
also  along  both  sides  of  the  Alps,  and  extend  on  through  the  Austrian  Alps ; 
and  after  an  interruption  about  Vienna,  appear  again  in  the  Carpathians. 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC.  775 

They  outcrop  along  the  Apennines,  the  Pyrenees,  and  east-central  Spain. 
They  cover  large  areas  in  central  and  northern  Russia.  The  beds  have  a 
small  development  along  the  Alps  compared  with  the  Triassic;  but  the 
fossils  and  rocks  show,  by  their  kinds,  that  the  great  continental  sea  was 
here  of  unusual  depth  and  purity. 

In  England  the  subdivisions  of  the  Jurassic  series  are  as  follows :  — 

1.  Liassic  Group. 

(1)  The   LOWER   LIAS,  consisting   of  clays,  shales,  and  gray  limestone, 
and  about  900  feet  thick. 

(2)  The  MIDDLE  LIAS,  or  Marlstone,  a  coarse  shaly   argillaceous   and 
ferruginous  limestone  with  sand-beds  and  clays ;  200  to  350  feet  thick. 

(3)  The  UPPER  LIAS,  consisting  of  clays  and  shales,  and  containing  lime- 
stone concretions  ;  200  to  300  feet  thick ;  with  the  Midford  sands  in  southern 
England  about  200  feet.     The  jet  of  the  Yorkshire  coast  is  a  compact  variety 
of  coal  from  the  Upper  Lias. 

These  subdivisions  were  named  in  France  by  D'Orbigny :  (1)  the  Sinemurian,  from 
the  Latin  word  for  the  town  of  SSmur ;  (2)  the  Liassian ;  and  (3)  the  Toarcian,  from 
Thouars,  in  western  France. 

2.  Oolytic  Group. 

(1)  The  LOWER  OOLYTE. 

Divided  into  (1)  the  Inferior  Oolyte,  which  includes  the  sandstones  or  Dogger  of  York- 
shire and  the  Cheltenham  beds  —  the  Bajocian  ;  and  (2)  the  Great  or  Bath  Oolyte  —  the 
Bathonian,  including  (a)  the  Fuller's  earth,  or  clay-beds  of  varying  thickness  up  to  400' 
in  Dorsetshire;  (&)  the  Stonesfield  slate,  a  thin-bedded  limestone  in  Oxfordshire, 
and  above  it ;  (c)  the  Forest  Marble,  consisting  of  sandy  and  clayey  layers  with  Oolyte ; 
and  (d)  the  Cornbrash,  a  coarse  shelly  limestone.  At  Brora,  on  the  east  coast  of  northern 
Scotland,  there  is  a  coal-bed  2£'  thick,  overlaid  by  beds  containing  Middle  Oolyte  fossils. 
In  Yorkshire,  the  Inferior  Oolyte  contains  estuarine  beds  with  thin  seams  of  coal  and 
many  remains  of  plants. 

(2)  The  MIDDLE,  or  OXFORD  OOLYTE. 

Divided  into  (1)  the  Callovian,  consisting  of  the  Kellaways  rock ;  (2)  the  Oxfordian, 
calcareous  sandstone  and  the  Oxford  clay ;  and  (3)  the  Corallian,  made  up  of  the  Coral 
rag  or  Coralline  Oolyte,  10'  to  120',  with  more  or  less  of  calcareous  grit,  5'  to  80'. 

(3)  The  UPPER,  or  PORTLAND  OOLYTE. 

Divided  into  (1)  the  Kimmeridgian,  or  Kimmeridge  clay,  having  ferruginous  con- 
cretions in  the  lower  division,  called  "  doggers  "  ;  (2)  the  Portlandian,  or  the  Port- 
land stone,  including  marlytes  and  limestone,  in  part  oolytic,  with  fresh-water  beds  ;  and 
(3)  the  Purbeckian,  or  Purbeck  beds,  well  displayed  in  Dorsetshire,  mostly  shales 
with  some  limestone  at  middle  which  is  partly  of  marine  origin,  10Q'  to  400'  thick,  and 
affording  remains  of  numerous  Insects  and  Mammals.  The  "Portland  dirt-bed"  is  at 
its  base. 

In  Europe  other  subdivisions  have  been  introduced,  for  which  see 
page  790. 


776 


HISTORICAL  GEOLOGY. 


The  "Black  Jura"  of  Germany  corresponds  to  the  Lias;  the  "Brown  Jura"  or 
"Dogger"  to  the  Lower  Oolyte  and  Callovian;  and  the  Upper  or  White  Jura,  or  Malm, 
to  the  rest  of  the  Middle  and  the  Upper  Oolytes,  from  the  Callovian  to  the  Portland  beds 
inclusive.  To  the  Kimineridgian  group  belongs  the  fine-grained  lithographic  limestone  of 
Solenhofen  at  Papenheim,  in  Bavaria,  near  Munich,  about  80'  thick,  noted  for  its  wonder- 
fully perfect  preservation  of  fossil  Crustaceans,  Squids,  Insects,  impressions  of  birds' 
feathers  and  of  wings  of  Pterodactyls. 

In  Peninsular  India,  in  the  district  of  Cutch,  the  beds  referred  to  the  Jurassic  have  a 
thickness  of  6000',  the  lower  chiefly  marine,  and  the  upper  as  prominently  fresh- water. 
Outside  of  the  peninsula  the  Jurassic  occurs  in  the  Salt  Range  and  northwest  Himalaya, 
with  characteristic  fossils. 

In  Australia,  Jurassic  rocks  with  many  fossils  have  been  observed  in  Western  Australia, 
of  the  periods  of  the  Middle  and  Upper  Lias  and  Lower  Oolyte;  and  in  Queensland,  of  the 
Upper  Oolyte  (C.  Moore,  Q.  J.  G.  Soc.,  1870). 

Aucella-bearing  beds  have  been  observed,  as  C.  A.  White  states  in  Becker's  Report 
(see  page  835),  near  Moscow,  in  Petschora-land,  near  the  Caspian,  in  northern  Siberia,  in 
Nova  Zembla,  Spitzbergen,  in  the  Kuhn  Islands  near  the  east  coast  of  Greenland,  in 
southern  India,  in  New  Zealand,  and  in  Brazil ;  and  they  have  been  referred  by  most 
authors  to  the  Jurassic ;  but  Professor  Eichwald  makes  them  Neocomian,  and  Zittel 
refers  those  of  New  Zealand  to  the  Jura  or  Lower  Cretaceous. 


LIFE  OF  THE  FOREIGN  JURASSIC. 

The  Lias  and  Oolyte  of  Britain  and  Europe  afforded  the  first  full  display 
of  the  marine  fauna  of  the  world  since  the  era  of  the  Subcarboniferous. 
Very  partial  exhibits  were  made  by  the  few  marine  beds  among  the  Coal- 
measures;  still  less  by  the  beds  of  the  Permian,  and  far  less  by  the  Triassic. 
The  seas  had  not  been  depopulated.  The  occurrence  of  over  4000 
invertebrate  species  in  Britain  in  the  single  Jurassic  period  is  evidence, 
not  of  deficient  life  for  the  eras  preceding,  but  of  extremely  deficient  records. 
Further,  this  meagerness  in  American  records  continued  until  the  Cretaceous 
period.  Moreover,  in  order  to  put  together  rightly  the  American  and  Euro- 
pean records,  it  is  necessary  to  note  that  the  events  of  the  epochs  of  the  Lias 
and  Lower  Oolyte,  with  their  vertebrate  life,  have  their  place,  according  to 

present  knowledge,  be- 
fore those  of  the  Ameri- 
can Atlantosaurus  bed  s ; 
that  is,  between  those 
of  the  Middle  Oolyte 
and  of  the  Triassic. 

PLANTS. — The  land 
plants  of  the  Juras- 
sic period  were  mainly 
Cycads,  Conifers,  Ferns, 

Fig.  1268,  Section  from  near  Lullworth  Cove,  showing  stumps  of  trees  and  Equisetd,  as   in  the 
in  the  Portland  "dirt-bed"  ;  1269,  stump  of  the  Cycad,  Mantellia mega-  T   •         •  j  pnvp<,     aTlfl 

lophylla  (x  A)-     Buckland.  TiaSSlC.        JjCa 

stems    occur    in   many 
strata,  and  especially  in  the  Lower  Oolyte  in  the  Yorkshire  beds  and  in  the 


1268. 


MESOZOIC    TIME  —  TRIASSIC    AND   JURASSIC. 


777 


Stonesfield  slate,  chiefly  near  Woodstock,  where  have  been  found  over  80 
spe'cies  of  Ferns,  nearly  20  of  Conifers,  and  40  of  Cycads.  The  Middle  and 
Upper  Oolyte  have  afforded  about  16  other  species.  The  Conifers  are  of 
the  genera  Taxites,  Thuyites,  Cupressites,  Araucarites,  —  names  which  express 
their  modern  relations.  There  were  also  Endogens  of  the  Arum  and  Pan- 
danus  families  ;  but  no  Angiosperms  or  Palms.  The  "  dirt-bed  "  at  the  base 
of  the  Pur  beck  has  afforded  stumps  of  Cycads  (Fig.  1268),  including  three 
species  of  Mantellia,  one  of  which  is  shown  in  Fig.  1269.  There  is  also  a 
species  of  Pine  (Pinites),  besides  a  few  other  plants. 

INVERTEBRATES.  —  Siliceous  Sponges,  both  the  Hexactinellid  (Fig. 
1270)  and  Lithistid  kinds,  were  very  common  in  the  Middle  and  Upper 
Oolyte,  and  so-called  sponge-beds  occur  in  the  European  Oolyte  at  different 
levels. 

Polyp-corals  were  of  many  kinds,  of  the  modern  Hexacoralla  type  (hav- 
ing the  rays  a  multiple  of  6).  The  Corals  flourished  like  the  species  of 


1272. 


1270. 


1271. 


SPONGE,  of  the  Oolyte.  —  Fig.  1270,  Tremadictyon  reticulatum.    POLYP-CORALS,  of  the  Oolyte.  —  Fig.  1271,  Mont- 
livaltia  caryophyllata ;  1272,  Isastrsea  oblonga.     D'Orbigny. 

modern  coral  reefs  (1)  in  the  pure  ocean  waters,  and  (2)  many  too  in  the 
shallow  waters  of  the  ocean's  borders,  as  about  modern  coral  reefs.  For 
(1)  the  limestones  make  several  alternations  with  the  sediments,  clays, 
and  sand-beds  of  the  sea  margins ;  and  (2)  only  the  purer  limestones  contain 
the  corals.  They  abound  in  England  in  some  beds  of  the  Lias,  in  both 
sections  of  the  Lower  Oolyte,  the  Inferior  and  the  Great  Oolyte,  in  the  Corallian 
of  the  Middle  Oolyte,  but  are  absent  from  the  Kellaway  beds  or  Oxford  clay 
of  the  Middle,  and  from  all  of  the  Upper  Oolyte  beds  in  England,  excepting 
a  single  species,  Isastrcea  oblonga  (Fig.  1272),  in  the  Portland  limestone. 
The  reef  species  of  the  Oolyte  may  have  flourished  at  greater  depths  than 
those  of  existing  reefs,  but  appear  not  to  have  been,  in  general,  abyssal 
species. 


The  most  of  the  species  of  the  Lias  are  of  the  genera  Montlivaltia  (M.  caryopliyllata^ 
Fig.  1271,  from  the  Bath  Oolyte),  Thecosmilia,  Astrocoenia,  Isastrcea;  and  excepting 
Astroccenia  these,  with  Thamnastrcea,  are  the  most  prominent  genera  in  the  Lower  Oolyte. 


778 


HISTORICAL   GEOLOGY. 


The  Isastrcea,  Thecosmilia,  and  Thavnnastrcea  corals  are  massive  kinds.  Etheridge's 
tables  for  British  fossils  in  1885  give  the  number  of  Jurassic  species,  in  all,  236,  and.  of 
these  the  genera  mentioned  contain  :  — 


Total 

Astroccenia 14 

Isastraea 24 

Montlivaltia 44 

Thecosmilia 21 

Thamnastraea 27 


Lias  Lower  Ob'lyte  Middle  Oolyte  Upper  Oolyte 
14                   0                   0  0 

10  18  4  1 

25  18  1  0 

14  6  1  0 

21  23  3  0 


Echinoderms  were  in  profusion,  as  in  existing  coral  seas.  Crinoids  were 
numerous  of  the  genera  Pentacrinus,  Apiocrinus,  and  others.  fPentacrinus 
(Extracrinus)  Briareus  (Fig.  1278)  is  one  of  the  common  and  most  re- 
markable of  the  species  in  the  Lias ;  a  bed  in  the  Lower  Lias  is  largely 


1273-1278. 


1273 


1278 


1277 


ECHINODERMS.— Fig.  1273,  Apiocrinus  Roissyanus  (x  |),  Oolyte,  the  middle  part  of  the  stem  omitted;  1274, 
Saccosoma  pectinata,  Oxfordian  ;  1275,  Pseudodiadema  seriale ;  1276,  Cidaris  Blumenbachii ;  1277,  spine  of  the 
last ;  1278,  Pentacrinus  (Extracrinus)  Briareus. 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC. 


779 


made  of  it  and  shells  of  Gryphcea  arcuata  (Etheridge) .  Apiocrinus  Roissyanus 
D'Orb.  (Fig.  1273)  is  from  the  Middle  Oolyte  of  Europe.  Saccosoma pectmata 
Ag.  is  a  Comatulid,  or  free  Crinoid,  from  the  Oxfordian  group.  Of  Echinoids, 
the  genera  Cidaris  (Fig.  1276),  Hemicidaris,  Pseudodiadema,  and  Hemapedina 
include  the  larger  part  of  the  species.  Pseudodiadema  seriale  (Fig.  1275)  is 
from  the  Lower  Lias. 

Brachiopods  of  the  spire-bearing  genera  had  their  last  species  in  the 
Jurassic  period.     These  excepted,  the  Jurassic  Brachiopods  were  mostly  of 


1279-1285. 
1280 


1282 


BRACHIOPODS.  —  Figs.  1279, 1280,  Cadomella  Moorei  (x  f) ;  1281,  same,  nat.  size ;  1282,  Spiriferina  Walcotti,  Lias ; 
1283,  Terebratula  digona,  Great  Oolyte ;  1284,  T.  diphya,  Tithonian ;  1285,  Ehynchonella  inconstans,  Kim- 
meridge. 

the   Terebratula,  Rhynchonella,   TJiecidium,  Lingula,  and  Discina   families, 
which  have  also  living  species. 

Lamellibranchs  were  of  several  new  genera.     Gryphcea  (Figs.  1287, 1290) , 
of  the  Oyster  family,  having  an  incurved  beak,  commenced  in  the  Lias  and 


1286. 


1287. 


LAMELLIBRANCHS.  —  Fig.  1286,  Lima  gigantea  (x  £),  Lias  ;  1287,  Gryphaea  incurva  (x|),  Lias. 

continued  into  the  Cretaceous.  Fig.  1287,  G.  incurva,  is  from  the  Lias,  and 
1290,  G.  dilatata,  is  from  the  Oxfordian  beds.  Exogyra  (Fig.  1289),  also  of 
the  Oyster  family,  is  another  characteristic  genus,  but  more  so  of  the  Ore- 


780 


HISTORICAL   GEOLOGY. 


taceous ;  the  beak  is  twisted  to  one  side,  as  is  implied  in  the  name.  Trigonia 
(Fig.  1291),  the  name  alluding  to  the  somewhat  triangular  form,  has  over 
100  Jurassic  species.  Another  peculiar  type  common  in  the  Middle  Oolyte 

1288-1293. 


1294. 


LAMELLIBEANCHS. — Fig.  1288,  Ostrea  Marshii,  Lower  Oolyte;  1289,  Exogyra  virgula,  Kirameridgian  ;  1290, 
Gryphsea  dilatata,  Callovian  ;  1291,  Trigonia  clavellata,  Corallian ;  1292,  Astarte  minima,  Corallian  ;  1293, 
Diceras  arietinuin,  Diceratian. 

in  the  northern  Alps  is  that  of  Diceras  (Fig.  1293),  a  species  in  which  the 
beak  of  each  valve  is  curved  spirally ;  it  is  related  to  the  modern  Chama.     Of 

existing  genera  having  many  Jurassic  species  there 
are  Ostrea,  Pecten,  Lima  (Fig.  1286),  Astarte  (Fig. 
1292),  Lucina,  Corbula,  Nucula,  Pholadomya,  and 
many  others. 

Gastropods  were  very  numerous.  The  number 
of  species  found  in  British  Jurassic  rocks  alone 
is  nearly  1000;  and  of  these  over  10  per  cent 
were  of  the  old  genus  Pleurotomaria,  the  number 
being  larger  than  for  all  preceding  time.  It  was 
the  culminating  time  for  the  type ;  only  two  living 
species  are  known.  Other  genera  of  many  species 
dating  from  the  Paleozoic,  and  also  modern,  are 
Trochus,  Turbo,  Patella,  Natica,  which  comprise 
25  per  cent  of  the  British  Jurassic  Gastropods ; 
and  among  the  many  of  Mesozoic  origin,  Cerithium  has  10  per  cent  of  all  the 


GASTROPOD.  —  Fig.    1294,     Neri- 
nea  Goodhallii,  Corallian. 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC. 


781 


species,  and  Chemnitzia  20  per  cent  (Etheridge) .  The  genus  Nerinea,  having 
one  or  more  ridges  in  the  spiral  cavity  (Fig.  1294)  is  confined  to  the  Oolyte, 
and  the  Cretaceous  period. 

Cephalopods  of  the  Ammonite  type  have  an  enormous  expansion  in  the 
period ;  250,  or  three-fifths  of  the  British  species,  occur  in  the  Lias.  Figs. 
1296,  a  are  from  the  Lower  Lias ;  1295  and  1297  from  the  Middle  Lias ; 


1295-1297. 


129T 


CEPHALOPODS  (Ammonites)  of  the  Lias.  — Fig.  1295,  Pleuroceras  spinatum  ;  1296,  a,  Coroniceras  Bucklandi ;  1297, 

^Egoceras  capricornus. 

1298,  from  the  Inferior  Oolyte  ;  1299,  from  the  Middle  Oolyte.  The  last  two 
figures  have  the  aperture  unbroken ;  and  in  1299  it  is  much  prolonged  on 
either  side. 


1298-1299. 


1299 


1298 


CEPHALOPODS  of  the  Oolyte.  — Fig.  1298,  Stephanoceras  Humphriesianum  ;  1299,  Cosmoceras  Jason. 

Besides  the  Cephalopods  with  external  chambered  shells  (Tetrabranchs), 
the  Belemnites  (Dibranchs)  (page  424)  were  of  many  species.  Figs.  1302, 
1303,  represent  the  bones  or  osselets  of  two  species,  in  their  ordinary 
broken  state;  and  Figs.  1300,  1301,  an  unbroken  one,  in  two  different 
positions. 


782 


HISTORICAL   GEOLOGY. 


Fig.  1305  represents  the  animal  of  an  allied  genus,  called  Belemnoteuthis. 
The  ink-bags  of  Belemnites  are  sometimes  found  fossil  (Fig.  1304),  and 


1800 


1300-1304. 


1801 


1802 


1802  a 


1304 


CEPHALOPODS.  —  Fig.  1800,  Complete  osselet  of  a  Belemnite,  side  view,  reduced ;  1301,  dorsal  view ;  1302,  a, 
Belemnites  paxillosus,  Middle  Lias  ;  1303,  B.  clavatus  ;  1304,  ink-bag. 

Buckland  states  that  he  had  drawings  of  the  remains  of  extinct  species  made 
with  their  own  ink. 

1305. 


Fig.  1305,  Belemnoteuthis  antiqua  (x  J),  of  the  Oxford  clay.     From  Mantell. 

Crustaceans  included  forms  of  modern  aspect,  and  among  them  species  of 
the  highest  of  the  divisions  of  Crabs,  the  Triangular  Crabs  —  Palseinachus 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  783 

of  Woodward.  Fig.  1307  is  one  of  the  Macrurans  from  Solenhofen,  and 
1308,  an  Isopod  related  to  the  modern  Oniscus,  from  the  Purbeck  beds  of 
England.  A  species  of  Astacus,  or  Lobster,  is  reported  from  the  Lias. 
Fig.  1310,  though  Spider-like,  is  a  Stomapod  Crustacean. 

1306-1310. 


ARTICULATES.  — Fig.  1306,  Libellula ;   130T,  Eryon  arctiformis;  1308,  Archaeoniscus  Brodiei ;  1809,  elytron  or 
wing-case  of  Buprestis  ;  1310,  Palpipes  priscus. 

Insects  of  all  the  prominent  tribes,  even  those  of  Dipters  and  Hymenopters, 
occur  as  early  as  the  Lias  ;  and  the  Hymenopters  belong  to  one  of  the  higher 
divisions,  that  of  the  Ants.  A  Lias  species  of  Ant  is  the  Palceomyrmex 
prodromus  of  Heer,  from  Switzerland.  Two  other  related  species  were 
described  by  Woodward  from  the  Purbeck  of  England.  Fig.  1306  represents 
a  Dragon-fly,  and  1319  a  Beetle's  wing-case  (a  Buprestis),  both  from  Solen- 
hofen ;  and  another  Dragon-fly,  Libellula  Brodiei,  is  from  the  Upper  Lias  of 
England. 

VERTEBRATES.  —  The  Jurassic  Vertebrates  included  Birds,  as  well  as 
Fishes,  Reptiles,  and  Mammals. 

1.  Fishes.  —  The  Fishes  were  Ganoids  and  Selachians.  Two  genera  are 
illustrated  in  Figs.  1311, 1312.  Pycnodus  had  many  species,  and  also,  among 
Selachians,  Hybodus,  Acrodus,  Strophodus  ;  and  among  Ganoids,  Lepidotas, 
and  others.  The  Ganoids  most  nearly  related  to  the  Teleosts  are  those  of 
the  Amia  family,  of  Pike-like  form,  species  of  which  occur  at  Solenhofen. 
The  Amioids  have  been  referred  to  the  Teleosts,  but  are  now  regarded  as  true 
Ganoids. 


784 


HISTORICAL   GEOLOGY. 


2.  Reptiles.  —  Sea-Saurians.  —  The  skeleton,  in  restored  form,  of  Ichthyo- 
saurus communis  is  represented,  T^  the  natural  size,  in  Fig.  1313  ;  the  head, 


1311-1312. 


1311 


GANOIDS.  —  Fig.  1811,  Dapedius,  restored  (x  &),  Lias;  1311  a,  scales  of  same;  1312,  Aspidorhyncus  (x  £), 

Solenhofen. 

reduced  to  -£$,  in  1314  ;  one  of  the  teeth,  natural  size,  in  1316 ;  and  a  vertebra 
in  1315.     The  Fish-like  biconcave  vertebrae  suggested  the  name  of  the  group, 

from  tx$v's?  fish)  and  o-avpos,  lizard. 

1313-1318. 


1C 


REPTILES.  —  Fig.  1313,  Ichthyosaurus  communis  (x  rJ5) ;  1314,  head,  id.  (x  ^,) ;  1315  «,  b,  view  and  section  of 
vertebra,  id.  (x  §) ;  1316,  tooth,  id.  (x  }) ;  1317,  Plesiosaurus  dolichodeirus  (x  ^) ;  1318  a,  6,  view  and 
section  of  vertebra  of  same. 

Of  Ichthyosaurians,  25  species  have  been  described  from  the  British 
rocks ;  and  of  these,  15  were  found  in  the  Lias,  and  7  in  the  Upper  Jurassic 
(Etheridge). 


MESOZOIC  TIME  —  TRIASSIC   AND  JURASSIC. 


785 


A  restoration  of  a  Plesiosaur,  —  a  long-necked,  somewhat  Turtle-like,  Sea- 
Saurian,  —  reduced  to  -^  the  natural  size,  is  given  in  Fig.  1317  ;  and  figures 
of  the  vertebrae  —  here  also  biconcave  —  in  1318  a,  6.  Fig.  1319  represents 
another  species,  Plesiosaurus  macrocephalus  Owen,  as  it  lay  in  the  rocks.  The 
figures  illustrate  the  long  Snake-like  neck  of  the  species,  the  short  body,  and 

1319. 


REPTILE.  —  Fig.  1319,  Plesiosaurus  macrocephalus  (x  &).    Buckland. 

the  character  of  the  paddles.  Pliosaurus  is  another  genus.  Out  of  47  British 
species  of  Plesiosaurids,  22  occur  in  the  Lias,  all  but  one  pertaining  to  the 
genus  Plesiosaurus.  The  group  continues  into  the  Upper  Jurassic,  which 
has  afforded,  in  Great  Britain,  12  species  of  Plesiosaurus,  six  of  Pliosaurus, 
and  one  of  Dinotosaurus  (Etheridge). 

The  Coprolites  (fossil  excrements)  of  the  Saurians  are  not  uncommon ; 
one  is  represented  in  Fig.  1322.  They  are  sometimes  silicified,  and,  notwith- 
standing their  origin,  are  beautiful  objects  when  sliced  and  polished. 

Dinosaurs.  —  The  earliest  discovered  of  the  Carnivorous  Dinosaurs  was 
the  Megalosaurus  Bucklandi  (1824).  The  length  of  the  skull  was  perhaps 
two  feet,  and  that  of  the  body  probably  30  or  40  feet.  It  appeared  in  the 
Lower  Lias  and  continued  through  to  the  Upper  —  a  length  of  survival  for 
such  a  species  that  is  most  extraordinary,  and  indicates  high  supremacy 
among  its  cotemporaries  —  if  the  apparent  short  life  limit  of  other  species  is 
DANA'S  MANUAL  —  50 


786 


HISTORICAL   GEOLOGY. 


not  merely  poor  luck  as  to  becoming  fossilized.     The  fore  limbs  were  much 
the  shorter  pair,  as  in  other  species  of  the  group. 

In  contrast  with  the  Megalosaurs  there  was  the  strongly  Bird-like 
Compsognathus,  from  Solenhofen,  C.  longipes  of  Wagner,  one  of  the  smaller 
Dinosaurs,  the  length  not  over  two  feet.  The  feet  were  all  three-toed ;  the 
fore  limbs  very  short,  the  hinder  long,  with  the  femur  shorter  than  the 
tibia ;  the  neck  long  and  slender ;  the  head  small,  but  well  armed  with  teeth,  — 
characters  indicating,  as  Huxley  states,  a  strong  resemblance  to  the  Bird  not 
only  in  general  form,  but  probably  also  in  an  erect  or  nearly  erect  posture  in 
walking.  It  is  perhaps  related  to  Hallopus  Marsh,  of  the  North  American 
Jurassic. 

1320. 


Mystriosaurus  Tiedemanni. 

Among  Herbivorous  Dinosaurs,  of  the  Sauropod  division,  the  largest 
European  species  known  was  the  Cetiosaurus  of  Owen  (1841),  related  to  the 
American  Morosaurus.  C.  Oxoniensis  was  40  or  50  feet  long,  "not  less  than 
10  feet  in  height  when  standing,  and  of  a  bulk  in  proportion."  The  femur 
is  64  inches  long.  -Cetiosaurian  remains  occur  in  the  Lower  and  Upper 
Oolyte,  and.  five  species  have  been  described. 


1321. 


1322. 


PXBBOSAUB.  —  Fig.  1321,  Pterodactylus  crassirostris  (x  |)  ;  1322,  Coprolite. 

Buckland. 


Fig.  1321,  from  D'Orbigny ;  1322, 


Another  genus  of  gigantic  Herbivorous  Dinosaurs  is  the  Iguanodon  of 
Mantell,  which  first  appears  in  the  Middle  Oolyte ;  it  was  of  the  Ornithopod 
group. 


MESOZOIC    TIME  —  TRIASSIC    AND    JURASSIC. 


787 


The  Omosaurus  armatus  of  Owen  (1875)  was  Stegosaurian,  and  perhaps, 
as  Marsh  suggests,  a  species  of  the  genus  Stegosaurus;  and  he  observes  that 
the  Scelidosaurus  of  Owen  is  an  allied  form. 

Crocodilians,  Lacertians,  Chelonians.  —  The  Crocodilians  were  represented 
by  Teleosaurs,  species  having  the  size  and  slender  head  of  the  Gavial  of  the 
Ganges,  but  with  biconcave  vertebrae.  Two  species  occur  in  the  Upper 


1323-1325. 


1325 


PTEKOSATTB. — Fig.  1323,  Rhamphorhynchus  phyllurus  (x  £) ;  1324,  caudal  oar  (x  t) ;  1325,  restoration  (x  $).    All 

from  Marsh. 


Lias  of  England,  and  five  others  in  the  Lower  and  Upper  Oolyte.  Fossil 
eggs  from  Cirencester  are  suspected  to  be  Teleosaurian  (Buckman).  The 
Mystriosaur  (Fig.  1320)  is  a  related  species  from  the  Lias  of  Europe. 

A  species  of  Lizard,  referred  to  the  genus  Lacerta,  occurs  in  the  Lower 
Oolyte  of  England.  Tortoises  (Chelonians)  are  found  in  the  Oolyte ;  and  a 
terrestrial  species,  Testudo  Stricklandi  Phillips,  in  the  Stonesfield  slate. 


788 


HISTORICAL   GEOLOGY. 


1326. 


Pterosaurs.  —  The  Pterosaurs,  or  flying  Lizards,  have  hollow  bones  like 
Birds.  The  genera  Dimorphodon,  characterized  by  a  long  tail,  and  Ptero- 
dactylus,  by  a  very  short  one  (Fig.  1321),  occur  in  the  Lias,  and  JRham- 
phorhynchus  (Figs.  1323-1325)  in  the  Stonesfield  slate  and  at  Solenhofen. 

Fig.  1321  represents  the  skeleton  (^  natural  size)  of  Pterodactylus  crassi- 
rostris;  it  was  a  foot  long,  and  the  spread  of  the  wings  about  three  feet. 
Fig.  1323  is  the  fthamphorynchus  phyllurus  of  Marsh,  from  Solenhofen,  Eich- 

stadt,  Bavaria,  and  1325  a 
restoration;  its  long  slen- 
der tail  ends  in  a  broad 
oar  (Fig.  1324).  The  fine 
specimen  in  the  Yale  Mu- 
seum, New  Haven,  Conn., 
has  an  impression  of  the 
wing  membrane,  showing  it 
to  be  without  feathers. 

3.  Birds. — Specimens 
of  birds  have  been  found  in 
the  lithographic  limestone 
of  Solenhofen,  with  nearly 
complete  impressions  of  the 
feathers  and  also  well-pre- 
served bones  of  the  limbs, 
heads,  and  most  other  parts 
of  the  skeleton.  They  per- 
tain to  a  single  species, — 
the  Archceopteryx  macrura 
of  Owen.  A  single  feather 
was  first  found  in  1860. 
This  was  followed,  two 
years  later,  by  the  dis- 
covery of  a  nearly  entire 
skeleton,  but  wanting  the 
head;  it  was  described  by 
Owen.  The  specimen  is 
now  in  the  British  Museum. 
Later,  a  third  and  still  more 
complete  skeleton  was  ob- 
tained, and  this  is  in  the 


BIRD.  —  Archaeopteryx  macrura  (x  $).    W.  Dames. 


Museum  at  Berlin.  It  has 
(1)  in  the  jaws  on  either 
side,  in  sockets,  13  Keptile-like  teeth;  (2)  a  long  vertebrated  tail,  having 
20  vertebrae,  each  carrying  a  pair  of  long  feathers ;  (3)  wing  bones  like 
those  of  the  fore  leg  of  a  normal  three-toed  Eeptile,  having  claws  at  the 
extremity;  (4)  four-toed  hind  limbs,  Bird-like  in  adaptation  to  biped  loco- 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC. 


789 


motion;  (5)  the  vertebrae  biconcave,  as  in  Fishes  and  many  Mesozoic 
Reptiles;  (6)  a  small  pelvis  with  the  bones  separate,  and  no  elongation  of  the 
pubes.  As  at  the  present  time  the  breed  of  fowls  having  feathered  legs  is 
produced  by  breeding  from  fowls  having  the  legs  scale-covered,  thus  sub- 
stituting feathers  for  scales,  the  succession  of  Birds  to  Reptiles  as  regards  this 
particular  point  is  not  so  strange  as,  at  first  thought,  it  might  seem  to  be. 

4.  Mammals.  —  Jurassic  Mammals  have  been  found  in  the  Stonesfield 
slate,  Lower  Oolyte,  and  in  the  Middle  Purbeck  beds.  As  in  America,  the 
species  are  probably  Marsupials,  and  Monotremes.  Among  the  species  at  the 
former  locality  are  Amphilestes  Broderipi  (Fig.  1327)  and  Phascolotherium 

1327-1328. 


1328 


MAMMALS.  —  Fig.  132T,  Amphilestes  Broderipi  (x  2)  ;  1328,  Phascolotherium  Bucklandi  (x  2).     Pictet. 

Bucklandi  (Fig.  1328).     The  genera  Plagiaulax,  Microlestes,  and   Tritylodon 
are  supposed  to  be  Monotreme. 

The  following  figures  of  jaw  bones  of  the  British  speoies,  of  natural 
size,  showing  the  dentition,  derived  chiefly  from  Owen's  papers,  are  copied 
from  Osborn's  review  of  the  Mesozoic  Mammalia. 

1329-1345. 


Fig.  1829,  Amphilestes ;  1330,  Amphitylus ;  1331,  Phascolotherium  ;  1332,  Triconodon  mordax ;  1333,  Peramus ; 
1334,  Spalacotherium ;  1335,  Peralestes ;  1336,  Peraspalax;  1337,  Leptocladus;  1338,  Amblotherium ; 
1339,  Phascolestes  ;  1340,  Achyrodon  ;  1341,  Stylodon  ;  1342,  Athrodon  ;  1343,  Bolodon  ;  1344,  Plagiaulax 
minor ;  1345,  Stereognathus.  All  natural  size. 


790  HISTORICAL  GEOLOGY. 

Characteristic  Species. 
1.  Lias. 

1.  LOWER  SINEMURIAN.  —  Ammonites  (^Egoceras)  planorbis,  A.  (  Coroniceras)  Buck- 
landi,  Ostrea  Liassica,  Gryphcea  arcuata,  Lima  gigantea,  Hippopodium  ponderosum,  Spiri- 
ferina  Walcotti,  Isastrcea  Murchisoni,  Pentacrinus  (Extracrinus)  Briareus,  Ichthyosaurus, 
Plesiosaurus.    The  "  White  Lias  "  or  Hettangian,  beneath  the  Sinemurian,  or  at  the  top  of 
the  Rhaetic,  contains  Ammonites  planorbis,  A.  Burgundies,  Cardinia  Listen,  C.  concinna, 
Pecten  Valoniensis. 

2.  MIDDLE  LIASSIAN.  — Ammonites  (Amaltheus}  spinatus,  A.  (A.}  ibex,  A.  (^Egoceras} 
Jamesoni,  Belemnites  paxillosus,   B.  clavatus,  Gryphcea  obliqua,  Avicula  incequivalvis, 
Inoceramus  substriatus,  Plicatula  spinosa,  Pentacrinus  subangularis. 

3.  UPPER  TOARCIAN.  —  Ammonites  (Harpoceras)  serpentinus,  A.  (Harpoceras)  bifrons, 
A.  (Lytoceras)  Jurensis,  A.  (Harpoceras')  radians,  Nautilus  Jurensis,  Belemnites  vulgaris, 
Leda  ovum,  Posidonomya  Bronni,  Ehynchonella  pigmcea,  Cadomella,  Spiriferina,  Pseudo- 
diadema Moorei,  Extracrinus  Briareus,  Ichthyosaurs,  Plesiosaurs,  Teleosaurus   Chap- 
manni  (at  Whitby). 

2.  Oolyte. 

1.  LOWER  OOLYTE.  —  (1)  Bajocian.     The  subdivisions  recognized  in  England  are 
those  of  Ammonites  (Harpoceras}  Murchisonce,  Lower ;  of  Stephanoceras  Humphriesianum, 
and  Cosmoceras  Parkinsoni,  Upper.     In  Europe  :  (a)  Aalenian,  with  Amm.  (Harpoceras} 
Murchisonce,  Ehynchonella  subangulata,  Terebratula  perovalis,  T.  fimbria,  Pecten  lens, 
Pholadomya  fidicula.     (6)  Bajocian,  with  Amm.  (Stephanoceras)  Humphriesianus,  A. 
(Cosmoceras)  Parkinsoni,  Astarte  obliqua,  Trigonia  costata,  Gryphcea  sublobata  (Gryphcea 
teds),  Ostrea  Marshii,  Rhynchonella  spinosa,  Terebratula  perovalis. 

(2)  Bathonian.  (a)  Vesulian  or  Fuller's  Earth,  with  Amm.  discus  (and  up  to  Corn- 
brash),  A.  Herveyi  (and  up  to  Forest  Marble),  A.  ferrugineus,  Anabacia  hemisphcerica, 
Pecten  vagans,  Ostrea  acuminata,  Ehynchonella  varians.  (b)  Bradfordian,  or  Great  (or 
Bath)  Oolyte,  with  Amm.  macrocephalus,  A.  aspidioides,  Ostrea  Marshii,  Pecten  lens, 
Ehynchonella  decorata,  E.  concinna,  Megalosaurus,  Cetiosaurus,  Pterodactylus,  Wald- 
heimia  digona,  Steneosaurus  ;  and  in  the  Stonesfield  slate,  at  the  base,  with  many  plants, 
Ostrea  Soioerbyi,  Ehynchonella  obsoleta,  Gervillia  acuta,  Ichthyosaurus,  Plesiosaurus, 
Teliosaurus,  Ehamphorhynchus,  Testudo  Stricklandi,  Chelys  Blakei,  Mammals.  In  Russia 
the  Oxford  Oolyte  is  overlaid  by  beds  called  the  Volgian. 

2.  MIDDLE   OOLYTE.  —  (1)    Oxfordian.     (a)    Callovian    or    Kellaways  Rock,   with 
Amm.  Gowerianus,  A.  macrocephalus,  Belemnites  Oweni,  B.  hastatus,  Gryphcea  bilobata, 
G.  dilatata,  Trigonia  paucicosta,  Terebratula  digona.     (b)  Oxfordian  or  Oxford  Clay, 
with  A  mm.  Lamberti  (up  to  Kimmeridgian),   A.   Marice,    Trigonia  clavellata,   Pecten 
vagans,  Avicula  incequivalvis,  Ehynchonella  socialis. 

(2)  Corallian.  (a)  Argovian,  Sponge-bearing  beds,  Scyphian-Kalk,  and  those  of 
Amm.  canaliculatus.  (b)  Corallian,  divided  into  Eauracian  or  Glyptician,  with  Glypticus 
hieroglyphicus,  Amm.  bimammatus,  Thecosmilia  annulata.  (c)  Isastrcea  explanata  and 
Diceratian,  with  Diceras  arietinum,  Nerinea  Defrancii.  The  Coral  Rag  and  Corallian 
Oolyte  of  the  Corallian  contain  Amm.  plicatilis,  Thamnastrcea  gregaria,  T.  concinna, 
Cidaris  jlorigemma,  Hemicidaris  intermedia,  Pseudodiadema  hemisphaericum,  Avicula 
ovalis,  Lima  rudis,  Perna  myliloides;  and  the  underlying  Lower  limestones,  Amm. 
cordatus,  Avicula  ovalis,  A.  expansa,  Pecten  fibrosus. 

3.  UPPER  OOLYTE.  —  (1)  Kimmeridgian.     (a)  Sequanian  or  Astartian,  with  Astarte 
minima,  A.  supracorallina,  A.  gregaria,  Ostrea  deltoidea,  Ehynchonella  corallina,  Amm. 
mutabilis,    A.    decipiens,    A.    tcnuilobatus,    Pseudodiadema    hemisphcericum,    Cidaris 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC.  791 

Jlongemma,  C.  Blumenbachii,  Apiocrinus  Meriani.  (6)  Pteroceriarij  with  Amm.  acanthi- 
cus,  Pterocera  oceani,  P.  ponti,  Nerinea  depressa,  Waldheimia  humeralis.  (c)  Virgulian, 
with  Gryphcea  virgula,  Trigonia  gibbosa,  Terebratula  diphya,  Pholadomya  multicostata, 
Thracia  depressa.  (d)  Bolonian,  with  Amm.  gigas,  A.  suprajurensis,  A.  biplex,  Trigonia 
incurva,  Cyprina  Brongniarti. 

(2)  Portlandian  or  TUJwnian.  (a)  Portlandian  or  Nerinean,  Amm.  gigas,  Trigonia 
gibbosa,  Gryphwa  virgula,  Ostrea  solitaria,  Lucina  Portlandica,  Perinea  trinodosa, 
Pterocera  oceani.  (6)  Purbeckian,  with  Corbula  inflexa,  C.  Forbesiana,  Cardium 
Purbeckense,  Terebratula  diphyoides,  Hemicidaris  Purbeckensis,  Astrcea  distorta,  Insects, 
Mammals. 

The  Tithonian  group  in  the  eastern  Alps  includes  a  coral  limestone  near  Salzkammer- 
gut,  and  the  Diphya  limestone  abounding  in  Terebratula  diphya ;  also  Aptychus  beds ; 
and  some  of  the  limestones  contain  many  Ammonites,  Phylloceras  ptychoicum,  and  others. 

The  Jurassic  beds  of  Cutch,  in  India,  contain,  in  the  Lower  Oolyte,  Astarte  com- 
pressa,  Corbula  pectinata,  Ehynchonella  concinna  ;  in  the  Middle  Oolyte,  Amm.  (Stepha- 
noceras)  macrocephalus,  A.  (Peltoceras)  athleta,  Terebratula  biplicata,  T.  sella,  and 
many  other  Ammonites,  many  Belemnites,  etc. ;  in  the  Upper  Oolyte,  Amm.  (Phylloceras} 
ptychoicus,  and  many  other  species.  Also  many  species  of  plants,  as  Sphenopteris  arguta, 
Alethopteris  Whitbyensis,  Otozamites  contiguus.  The  Portlandian  beds  afford  Trigonia 
Smeei  and  T.  ventricosa,  the  latter  also  a  South  African  species ;  also  jaw  of  a  Plesiosaur. 

The  Upper  Jurassic  of  the  Zanskar  area  in  the  central  Himalayas  has  afforded 
Belemnites  clavatus,  Ammonites  macrocephalus,  A.  Parkinsoni,  A.  biplex,  Trigonia 
costata,  and  other  species.  The  Hundes  area  in  the  Tibetan  Himalayas  also  has  many 
Jurassic  species.  (Cf.  Medlicott  and  Blandford,  Geology  of  India,  vols.  i.  and  ii.,  1879, 
and  second  edition  by  Oldham,  1894.) 

In  western  Australia,  20  species  of  Liassic  and  Oolytic  fossils  are  identical  with 
British  species :  3  of  the  Ammonite  group,  Nautilus  semistriatus  and  Gresslya  donaci- 
formis  of  the  Upper  Lias ;  Myacites  Liassinus  of  the  Middle  Lias  ;  and  2  of  the  Ammonite 
group,  with  Belemnites  canaliculatus,  Cucullcea  oblonga,  Pholadomya  ovulum,  Avicula 
Munsteri,  A.  echinata,  Pecten  cinctus,  P.  calvus,  Lima  proboscidea,  L.  punctata,  Ostrea 
Marshii,  Ehynchonella  variabilis,  Cristellaria  cultrata,  of  the  Oolyte  (C.  Moore). 

CONTINENTAL   RESEMBLANCES    AND    CONTRASTS  IN  THE  TRIASSIC  AND  JURAS- 
SIC PERIODS;   CLIMATE. 

The  Triassic  formation  is  alike  over  a  large  part  of  Europe  and  America  in 
kinds  of  rocks,  in  paucity  of  fossils,  and  in  evidences  of  shallow-water  origin, 
and  of  largely  brackish  water,  if  not  fresh.  The  continental  surface  in  each 
case  was  very  near  or  above  the  water  level  over  large  areas ;  and  it 
oscillated  between  brackish  or  fresh-water  flats  and  barren  or  half-barren 
salt-water  flats  or  sea-border  salt-pans.  The  European  exception  is  in  the 
Mediterranean  region.  Not  only  is  this  general  fact  true  for  the  two  conti- 
nents mentioned,  but  also  for  India,  South  Africa,  and  Australia,  or  the 
continental  regions  in  the  opposite  hemisphere.  This  so  general  prevalence 
over  large  parts  of  the  continents  of  slight  submergence,  too  slight  for  abun- 
dant remains  of  marine  life,  —  although  this  life  must  undoubtedly  have 
been  as  profuse  in  kinds  as  in  any  earlier  or  later  era,  —  indicates  general 
and  synchronous  movements  in  the  earth's  surface,  and  correlate  progress 
in  continental  growth.  The  Jurassic  period  was,  in  contrast,  a  period  of 
somewhat  deeper  and  clearer  seas,  sustaining  at  many  levels  abundant  life, 


792  HISTORICAL   GEOLOGY. 

but  still  with  wide  differences  between  the  continents  as  to  the  extent  of 
such  seas. 

It  is  an  interesting  fact,  bearing  on  the  conditions  under  which  the 
Liassic  beds  were  made,  and  the  facility  with  which  the  clear  open  waters  of 
a  fossiliferous  limestone  horizon  may  change  to  the  confined  waters  of  a  sea 
border,  that  a  bed  of  limonite  or  ferruginous  limestone  occurs  in  the  Lower 
Lias  northwest  of  Lincolnshire,  England,  which  is  27  feet  thick,  and  in  the 
Upper  Lias,  near  Bath,  two  feet  thick ;  on  the  continent,  in  Lorraine,  in  the 
Upper  Lias,  10  to  50  feet  thick,  containing  Ammonites,  a  Gryphcea,  Trigonia 
navis,  etc. ;  in  Auxois,  France,  near  the  base  of  the  Lower  Lias  overlying  a 
bed  of  "lumachelle"  limestone;  and,  as  stated  by  C.  Moore,  in  western 
Australia,  in  the  Middle  Lias,  a  very  ferruginous  limestone,  which  on  analysis 
gave  49  to  56  per  cent  of  metallic  iron.  Moore  goes  so  far  as  to  regard  the 
ferruginous  bed  of  Australia  as  proof  of  Liassic  age ;  the  associated  fossils 
are  much  better  evidence. 

But  with  all  the  resemblance  in  physical  conditions  between  Europe  and 
America,  there  was  a  remarkable  contrast  in  the  abundance  of  marine  life  in 
the  continental  seas.  This  contrast  was  especially  great  in  the  Jurassic 
period.  The  number  of  species  of  Jurassic  Invertebrates  thus  far  described 
from  the  American  rocks  is  less  than  250 ;  very  few  of  these  are  Corals, 
17  are  Cephalopoda,  5  Echinoderms,  17  Gastropods,  113  Lamellibranchs 
(Whitfield).  In  the  Jurassic  of  Great  Britain  alone  the  number  of  known 
marine  species,  as  stated  by  Etheridge  (GfeoL,  1885),  is  over  3900  ;  those  of 
Corals  236,  Echinoderms  208,  Ammonites  417,  Belemnites  112,  Gastropods 
988,  and  Lamellibranchs  1319.  More  study  may  quadruple  the  number  of 
American  species ;  but  this  will  little  diminish  the  contrast. 

As  indications  of  the  climate  of  the  Triassic  and  Jurassic  periods,  there 
are  these  pertinent  facts  from  the  Arctic  regions :  that  the  species  Ceratites 
Malmgreni,  Ammonites  Gaytani,  Nautilus  Nordenskioldi,  Halobia  Lommeli, 
H.  Zitteli  were  living  in  the  Spitzbergen  seas  during  the  Triassic  period; 
and  Ammonites  (Harpoceras)  M'Clintocki,  Monotis  septentrionalis,  and  species 
of  Pleurotomaria  and  Nacula,  about  Bathurst  Island,  Exmouth  Island,  and 
Prince  Patrick  Island,  probably  during  the  Jurassic  period,  —  species  that  have 
closer  relations  to  European  than  to  American  species  (Haughton,  Waagen)  • 
that  Iclitliyosaurs  were  living  in  Triassic  or  Jurassic  time  about  Exmouth 
Island  (77°  16'  K,  96°  W.),  their  remains  having  been  found  on  this  island 
by  the  Belcher  Expedition ;  and  that  other  Ichthyosaurs  existed  in  the  Spitz- 
bergen seas,  probably  during  the  Triassic  period,  remains  of  two  having  been 
found  by  Nordenskiold,  which  have  been  named,  by  Hulke,  Ichthyosaurus 
Nordenskioldi  and  /.  Polaris  ;  that  another  Saurian  —  "  probably  a  Dinosaur, 
allied  to  the  Anchisauridae,"  inhabited  the  region  about  Bathurst  Island, 
Captain  Sherard  Osborn  having  brought  home  a  vertebra,  which  has  been 
made  a  basis  of  a  species  named  by  A.  L.  Adams  Arctosaurus  Osborni. 

The  continent  of  North  America,  as  already  explained  (page  47),  is 
peculiar  in  climatal  situation.  It  has  the  Gulf  Stream  warm  with  tropical 


MESOZOIC    TIME  —  TBIASSIC    AND   JURASSIC.  793 

heat,  flowing  northward  and  eastwardfciear  its  eastern  border,  but  not  much 
for  the  warming  of  North  American  waters  north  of  Cape  Hatteras ;  its 
heat  is  carried  on  for  distribution  over  northern  and  western  Europe  and  the 
Arctic  seas.  Heading  off  the  Gulf  Stream  from  the  American  coast  north  of 
Hatteras,  there  flows  from  the  north  a  current  of  Arctic  waters,  that  makes  its 
escape  from  the  polar  basin  by  the  only  large  passage  way  out  —  the  way 
leading  into  the  Atlantic ;  and  these  cold  waters  are  like  a  cold  wall  along 
the  eastern  side  of  the  continent.  The  American  coast  has  a  means  of  pro- 
tection against  the  polar  current,  through  an  elevation  of  the  border  sufficient 
to  make  Newfoundland  a  peninsula  by  closing  the  Strait  of  Belle  Isle. 
Moreover,  if  the  elevation  were  only  500  feet,  the  eastern  cape,  around  which 
the  cold  current  would  be  forced  to  flow,  would  be  set  250  miles  east  of  its 
present  position. 

On  the  Pacific  side  a  cold  northwestern  current  follows  the  coast  of  North 
America  from  Alaska  southward,  as  part  of  the  normal  oceanic  circulation. 

Thus  at  the  present  time  North  America  has  relatively  cold  waters  along 
both  its  eastern  and  western  shores.  Hence  there  is  reason  enough  for  the 
paucity  of  its  existing  marine  faunas.  In  Paleozoic  time  this  contrast  with 
Europe  did  not  exist,  or  only  to  a  small  degree ;  for  the  Paleozoic  species  even 
exceed  in  numbers  those  of  Europe.  The  Arctic  basin  was  probably  open 
widely  in  all  directions.  But  in  the  early  Mesozoic  it  must  have  become  the 
closed  basin  which  it  now  is,  with  its  only  free  outlet  into  the  Atlantic ;  and 
in  this  way  the  continent  of  North  America  was  thus  early  put  between 
northern  cold  Atlantic  and  cold  Pacific  currents. 

The  actual  difference  of  temperature  between  the  waters  of  the  North 
American  and  European  sides  of  the  Atlantic  in  the  Triassic  and  Jurassic 
periods  is  uncertain,  because  no  marine  fossils  of  these  periods  have  been 
found  on  the  American  side.  On  the  European  side  the  presence  of  warm 
seas  is  proved  by  the  profusion  of  marine  species  and  by  their  kinds.  The 
coral  reefs  of  the  Oolyte  in  England  consist  of  corals  of  the  same  group  with 
the  reef-making  species  of  the  existing  tropics.  This  favors  the  conclusion 
that  the  British  waters,  and  nearly  all  the  European,  were  within  the  coral- 
reef  temperature  limit ;  that  is,  the  line  along  which  68°  F.  is  the  mean  tem- 
perature of  the  year.  The  Oolytic  isocryme  of  68°  F.  (see  map,  page  47), 
accordingly,  would  have  had  nearly  the  position  of  the  line  of  44°  F.  in  exist- 
ing seas,  but  with  a  little  less  northing  and  more  leaning  to  the  eastward. 
The  Gulf  Stream  was  the  probable  cause  of  this  long  northward  extension 
of  warm  waters  in  Jurassic  time. 

Further,  in  Europe,  according  to  Neumayr,  differences  in  the  climate  of 
the  later  Jurassic  are  indicated  by  the  distribution  of  fossil  Invertebrates. 
The  Mediterranean  Province,  or  that  of  southern  Europe,  including  the 
regions  of  the  Alps  and  Carpathians,  Italy,  Spain,  and  the  Balkan  peninsula, 
is  characterized  by  Ammonites  of  the  genera  Phylloceras,  Lytoceras,  and 
Simoceras,  with  the  Brachiopod  Terebratula  diphya.  The  Middle  European 
Province,  comprising  the  region  of  the  Juras,  France,  Germany,  England, 


794  HISTORICAL   GEOLOGY. 

and  the  vicinity  of  the  Baltic,  has  f ey  species  of  Phylloceras  and  Lytoceras, 
and  very  many  of  Harpoceras,  Oppelia,  Peltoceras,  and  Aspidoceras,  and  coral 
reefs  have  great  extent.  The  north  Russian  or  Boreal  province  has  in  its 
Jurassic  rocks  no  species  of  Lytoceras,  Phylloceras,  and  Haploceras,  and  no 
coral  reefs,  while  those  of  Cardioceras  and  Aucella  are  widely  distributed. 
On  the  other  hand,  the  flora  of  the  earliest  part  of  the  following  Cretaceous 
period  in  Greenland  included  an  abundance  of  Cycads. 

Although  the  cold  of  the  Atlantic  and  Pacific  barriers  of  North  America 
was  manifestly  of  little  severity,  it  was  enough  for  wide  results  in  the 
geographical  distribution  of  species. 

The  Mexican  Gulf  was  a  source  of  warm  waters  for  southern  and  interior 
North  America,  while  at  the  same  time  the  Arctic  seas  may  have  sent  down 
polar  currents  over  its  northwestern  interior  during  the  Triassic  period. 
The  effects  of  the  cold  northwesterly  currents  of  the  Pacific  border  are 
plainly  seen  in  the  many  species  peculiar  to  that  coast,  and  prominently  in 
the  Aucellae,  which  are  related  to  the  Siberian  species. 

BIOLOGICAL  CHANGES  AND  PROGRESS. 

Some  of  the  Successional  Lines. 

It  is  noteworthy  that  the  new  types  of  the  Jura-Trias  did  not  appear  at 
equable  intervals  successively  along  the  era.  They  were  rather  evolvings 
in  its  commencing  part,  the  Triassic,  the  opening  period  of  Mesozoic  time. 
The  Triassic  period  is  thus,  after  the  Cambrian,  which  opened  the  Paleozoic, 
the  most  eventful  in  the  earth's  biological  history ;  that  is,  the  most  pro- 
ductive of  great  branchings  in  the  higher  departments  of  the  Animal 
Kingdom  —  the  type  of  Mammals,  that  probably  of  Birds,  and  those  of  each 
of  the  grand  divisions  of  Eeptiles  excepting  such  as  had  already  appeared  in 
the  Permian.  This  is  true  also  of  the  modern,  or  nearly  modern,  style  of 
Orthopters,  Neuropters,  and  Coleopters  among  Insects,  as  illustrated  by 
Scudder ;  and  the  Lias  completed  the  display  of  the  system  of  Insects  by  the 
introduction  of  the  Dipters  or  Flies,  and  of  Hymenopters  as  represented  by 
Ants  and  other  families.  It  is  to  be  admitted,  however,  that  part  of  the 
developments  indicated  by  the  relics  in  Triassic  beds  may  date  from  the 
Permian.  The  physical  change  of  a  purified  atmosphere  prepared  the  way 
for  terrestrial  life  ;  and  the  preparation  was  essentially  complete  before  the 
close  of  the  Permian. 

This  crowding  together  of  the  origins  of  so  many  types  in  connection 
with  the  barrenness  of  most  Triassic  regions  makes  it  doubtful  whether  facts 
illustrating  the  precursor  lines  will  ever  be  fully  made  out. 

As  regards  the  precursors  of  Mammals,  their  closer  relation  to  Amphib- 
ians than  to  Reptiles  is  proved,  as  Huxley  first  pointed  out,  by  the  fact  that 
Amphibians  and  Mammals  have  two  occipital  condyles,  and  Reptiles  and 
Birds  but  one ;  and  hence  their  derivation  was  almost  certainly  from  some 
Amphibian  type,  and  not  from  a  Reptilian.  The  Monotremes  (of  which  but 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC.  795 

three  species  exist,  one  of  Ornithorhynchus  and  two  of  Echidna)  are  the 
lowest  of  Mammals,  and  have  many  Amphibian  and  Eeptilian  characters  in 
their  skeleton,  besides  that  striking  one  of  bearing  eggs,  like  Reptiles  and 
Birds.  They  are  called  Prototheria  in  some  zoological  systems;  and  this 
they  undoubtedly  are  in  type,  though  the  Duck-like  bill  and  webbed  foot  of 
the  Ornithorhynchus  are  unquestionably  degenerate  characteristics ;  for  the 
earliest  species  had  almost  certainly  a  full  set  of  teeth.  That  they  were 
first  in  origin,  however,  is  far  from  proved. 

Among  Reptiles,  the  Permian  type  represented  by  the  genus  Palceohat- 
teria,  with  the  associated  Hhynchocephalia,  as  explained  on  page  707,  is  the 
most  generalized  or  comprehensive  of  the  class.  Besides  its  Amphibian  rela- 
tions on  one  side  and  its  Reptilian  on  the  other,  it  has,  as  Baur  explains, 
characteristics  also  of  Birds  and  Mammals.  This  author  regards  the  type 
as  the  precursor  type  of  the  class  of  Reptiles  and  also  of  the  class  of  Birds. 
It  is  like  Mammals,  he  states,  and  unlike  all  other  Reptiles,  except  the  Rhyn- 
chocephs,  in  having  the  foramen  of  the  distal  end  of  the  humerus  on  the 
inner  side  of  the  epicondyle ;  in  other  Reptiles  it  is  on  the  outer  side  or  is 
absent ;  and  it  is  absent  from  all  Amphibians  and  Birds.  It  is  probable, 
therefore,  that,  nearly  as  Baur  concludes,  the  line  from  the  Amphibians 
which  gave  off  a  Rhynchocephalian  branch,  later  gave  off  a  Mammalian. 

The  relation  of  Birds  to  the  Dinosaurs  in  pelvis  and  hind  limbs,  especially 
to  the  Carnivorous  kinds,  was  pointed  out  by  Huxley ;  and  it  is  supposed 
that  the  two  types  may  have  originated  from  a  common  type  in  either  the 
Triassic  or  Permian  period.  The  Jurassic  bird,  Archaeopteryx,  which  is  so 
remarkably  Reptilian,  has  the  long  limbs,  and  but  little  else,  of  a  Dinosaur ; 
and  this  feature  in  the  hind  limbs  of  both  is  partly  a  consequence  of  an 
elongation  of  the  metatarsals.  The  cranium  and  the  sternum  are  Bird-like, 
but  not  so  the  fore  limbs,  pelvis,  and  some  other  parts.  The  Berlin  specimen 
was  first  described  as  a  Reptile  by  Carl  Vogt.  The  relations  of  Birds  to 
Dinosaurs  in  the  structure  of  the  skeleton  are  largely  a  consequence  of  the 
demands  made  by  the  animal  on  its  hind  limbs ;  and  the  unlike  demands  on 
the  fore  limbs  are  the  source  of  divergences. 

General  Changes  Attending  Biological  Progress. 

1.  Reduction  in  multiplicate  numbers.  —  The  reduction  in  number  of  pos- 
terior vertebrae  when  the  Fish  type  passed  to  that  of  the  Amphibian  has  been 
noticed  on  page  726.  Their  absence  from  the  upper  lobe  of  the  tail  in  most 
Triassic  Ganoids,  rendering  the  Fish  homocercal  in  place  of  heterocercal,  is  a 
change  in  the  same  direction,  like  that  which  takes  place  when  the  Tadpole 
becomes  a  Frog,  or  the  young  of  a  Ganoid  or  other  Fish  loses  a  caudal  lobe, 
or  some  caudal  vertebrae,  when  becoming  adult.  The  long  vertebrated  tail  of 
the  Jurassic  Bird  was  a  related  multiplicate  feature,  which  disappeared  early 
in  Cretaceous  time,  if  not  before  it. 

The  reduction  of  the  number  of  parts  in  the  limbs  of  Fishes  before  the 
close  of  the  Paleozoic  to  the  typical  number  of  five  for  the  digits  in 


796  HISTORICAL   GEOLOGY. 

Amphibians,  and  to  typical  numbers  and  arrangement  in  the  bones  of  the  leg, 
has  been  stated  on  page  726.  Once  reached,  these  numbers  remain  the 
normal  or  typical  numbers  for  Reptiles,  Birds,  and  Mammals.  The  typical 
number  of  cervical  vertebrae,  seven,  sometimes  occurs  in  Reptiles ;  but  varia- 
tion from  this  number  is  not  in  them  a  character  of  generic  importance. 

Under  Mammals,  the  differentiation  of  the  teeth  in  all  typical  species,  into 
incisors,  canines,  and  molars,  exists,  commencing  with  Triassic  Marsupials ; 
but  the  number  of  teeth  continues  to  be  multiplicate  through  the  Jurassic, 
the  typical  Mammalian  number,  44,  being  usually  exceeded,  and  sometimes 
by  24.  The  number  seven  became  the  fixed  or  normal  number  of  cervical 
vertebrae,  first,  among  Vertebrates,  in  Mammals.  It  is  a  character  of  all 
existing  Marsupials,  and  probably  was  of  those  of  the  early  Mesozoic,  —  a 
doubt  remaining  because  no  skeleton  of  an  ancient  species  has  yet  been 
found. 

Exceptions  to  normal  numbers,  after  they  were  once  attained,  have  pro- 
ceeded from  Specializations  in  the  course  of  upward  as  well  as  downward 
progress  ;  but  the  larger  part  occur  among  degenerate  forms,  and  in  these,  as 
the  examples  mentioned  show,  the  divergence  is  often  very  great. 

2.  Location  of  the  function  of  locomotion.  —  As  remarked  on  page  726,  the 
typical  Amphibian,  on  becoming  adult,  passes  from  the  stage  of  caudal  or 
urosthenic  locomotion,  to  locomotion  by  limbs,  or  podostlienic.  The  latter  is 
the  typical  condition  in  Reptiles,  Birds,  and  Mammals.  But  groups  under 
each  differ  as  to  the  pair  of  limbs  which  bears  the  chief  part  of  the  work. 

The  Triassic  and  Jurassic  periods  were  distinguished  eminently  by 
hind-limb  location  of  force  and  locomotion.  It  was  the  era  of  very  small 
brains,  and  of  great  development  of  the  posterior  extremities  —  the  era  of 
Merosthenic  Vertebrates,  as  the  Devonian  and  Carboniferous  eras  were  of 
Urosthenic  Vertebrates.  The  prominent  feature  of  all  Dinosaurs  is  their 
enormous  hinder  parts.  Moreover,  as  has  been  mentioned,  many  of  the 
species,  the  gigantic  Stegosaurs  preeminently,  have  a  provision  for  this 
arrangement  of  the  forces  of  the  Reptile,  as  Marsh  first  brought  out,  in  the 
great  nervous  mass  of  the  sacrum. 

The  Amphibians  also  were  strongest  in  the  hind  limbs,  as  is  indicated  by 
the  remains  of  the  Labyrinthodonts.  The  wings  of  the  Jurassic  Bird  of  Solen- 
hofen  prove  that  they  were  poor  flyers,  and  consequently  that  their  legs  or 
hind  limbs  were  their  chief  locomotive  organs.  Moreover,  in  this  merosthenic 
era,  the  Mammals  probably  had  the  hind  limbs  much  the  stronger  of  the  two 
pairs,  as  is  true  of  modern  Marsupials. 

The  species  of  Reptiles  that  were  distinctively  strong  in  the  fore  limbs,  or 
prosthenic,  are  the  Pterosaurs ;  and  among  these,  the  Pterodactyls,  having 
the  head  large,  the  posterior  feet  small,  and  the  tail  short,  with  the  brain 
and  sternum  Bird-like,  appear  to  have  taken  the  lead.  Seeley  has  placed 
them  in  an  independent  group  separate  from  Reptiles.  The  absence  of  scales 
from  the  body,  and  the  light  bones,  with  air  cavities  and  pneumatic  foramina, 
still  further  ally  them  to  Birds,  and  separate  them  from  other  Reptiles.  It 


MESOZOIC    TIME  —  TRIASSIC    AND   JURASSIC.  797 

is  probable,  therefore,  that  this  highly  specialized  type  ranked  above  all  other 
Reptilian  types  of.  the  Jurassic. 

3.  Degeneration.  —  Progress  in  a  type  from  toothed  jaws  to  toothless  must 
be  viewed  as  a  decline,  although  there  may  be  true  progress  in  other  respects. 
Among  the  Rhynchocephalians  —  which,  in  the  Permian  genus  Palwohatteria, 
have  numerous  formidable  teeth — occur  later  species  having  a  horn-covered 
extremity  of  the  jaws  like  the  beak  of  a  turtle.     Again,  the  Dinosaurians 
vary  from  many-toothed,  tiger-mouthed  species,  to  those  with  few  teeth. 

The  Plesiosaurians  are  supposed  to  be  degenerate  land  Eeptiles,  whose 
limbs,  even  in  the  Triassic,  had  become  paddles,  with  fingers  multiplicate 
in  number  of  phalanges;  and  the  Ichthyosaurs,  species  of  some  other 
Reptilian  type,  carried  downward  to  a  still  lower  urosthenic  stage,  in  which 
the  pelvic  girdle  had  become  nearly  obsolete,  and  the  fingers  sometimes 
excessive  in  number,  as  well  as  multiplicate  in  segments.  Turtles  are  other 
degenerate  forms  of  the  Triassic  as  well  as  of  the  Jurassic  period. 

Such  facts  make  it  manifest  that  through  geological  time  progress  in  the 
Vertebrate  type,  as  in  the  Invertebrate,  was  downward  as  well  as  upward  j 
that  degeneration,  while  it  may  make  obsolete,  may  also  return  a  species  to 
a  low  multiplicate  condition,  in  which  the  multiplicate  characteristic  extends 
to  the  number  of  vertebrae,  to  the  teeth,  to  the  fingers,  to  the  number  of 
finger  bones,  and  to  other  parts  of  the  structure.  It  is  atavism  under  some 
physiological  law  deeper  than  atavism,  bringing  back  characters,  not  of  the 
earlier  Reptiles,  but  of  the  earliest  Vertebrates,  the  Fishes,  yet  not  without 
any  loss  of  the  fundamental  characteristics  of  Reptiles. 

Considering  the  very  long  time  that  Fishes  were  in  the  seas  before  the 
rise  in  grade  to  the  terrestrial  type  of  the  Amphibian,  and  the  relatively 
short  time  for  the  much  greater  rise  from  the  Amphibian  to  the  Reptile,  Bird, 
and  Mammal,  there  is  no  reason  to  believe  that  any  of  the  upward  successional 
lines  passed  through  the  water.  Through  the  water,  for  terrestrial  Verte- 
brates, as  many  examples  show,  was  a  quick  way  down  in  grade,  not  a 
possible  way  up. 

4.  A  fragment  of  the  Triassic  world.  —  Australia  is  often  spoken  of  as  a 
Triassic   continent.     As   the  world  in  Triassic  time  had   only   Marsupials 
and  Monotremes  for  its  Mammals,  so  Australia  has  now,  man's  encroach- 
ments excluded,  Marsupials  and  Monotremes  for  its  only  Mammals.     The 
existence  there  of  a  species  of  Bat,  and  of  some  Mice  and  Rats,  is  hardly  an 
exception  to   be  considered.     But  although  thus  restricted  in  its  modern 
fauna,  its  Mammals  are  not  of  few  kinds  ;  for,  as  Wallace  states,  "  some  are 
carnivorous,  some  herbivorous ;  some  arboreal,  others  terrestrial ;  there  are 
insect  eaters,  fruit  eaters,  honey  eaters,  leaf  or  grass  feeders ;  some  resemble 
wolves,   others   marmots,  weasels,   squirrels,   flying   squirrels,    dormice,   or 
jerboas."     Moreover,  one  of  the  last  four  species  of  Cestraciont  Sharks,  a 
tribe  of  Mesozoic  and  Paleozoic  affinities,  the   Cestracion  Philippi,  or  Port 
Jackson  Shark,  lives  in  Australian  seas ;  and  one  of  the  last  three  species  of 
the  Dipnoans,  the  Ceratodus,  Carboniferous  and  Triassic  in  type,  inhabits  its 


798  HISTORICAL   GEOLOGY. 

interior  waters.  Besides,  the  surface  rocks  of  the  continent  are  to  a  large 
extent  Permian,  Triassic,  or  Jurassic.  Marsupials  and  Monotremes  formerly 
had  a  wide  range  over  the  globe.  A  large  Echidna,  or  Monotreme  Porcupine, 
was  among  the  species  of  England  in  the  Middle  Quaternary ;  and  Marsupials, 
among  the  Mammals  of  Europe  and  America  in  the  Tertiary ;  but  at  the 
present  time  the  few  of  South  and  North  America  are  all  that  exist  out  of 
Australia.  It  cannot  be  affirmed  that  Triassic  Australia  was  the  source  of 
all  the  Marsupials  of  the  world ;  but  there  is  little  doubt  that  its  only  Triassic 
Mammals  were  Marsupials  and  Monotremes. 

It  has  already  been  explained  that  New  Guinea  and  New  Zealand  show 
by  their  faunas  that  they  were  once  parts  of  a  great  Australasian  continent, 
New  Guinea  having  its  Marsupials,  and  New  Zealand  the  only  surviving 
species  of  the  Permian  and  Triassic  tribe  of  Rhynchocephalians,  in  a  species 
of  the  genus  Hatteria.  The  possible  extension  of  the  continent  southward, 
and  its  union  for  a  time  with  an  Antarctic  continent,  are  considered  on  page 
737. 

DISTURBANCES  AND  UPTURNINGS  DURING,  OR  AT  THE  CLOSE  OF,  THE  TRIASSIC 

AND  JURASSIC  PERIODS. 

Triassic  of  the  Atlantic  border. 

The  Triassic  areas  of  the  Atlantic  border  bear  evidence  of  a  general 
upturning,  in  which  the  beds  were,  with  small  exceptions,  raised  not  into 
flexures,  but  into  monoclines.  The  effects  of  the  movements  have  been 
briefly  stated  on  page  357,  under  the  subject  of  mountain-making.  Additional 
facts  and  illustrations,  respecting  the  disturbed  areas,  and  the  orographic 
results  and  methods,  are  here  presented. 

The  close  parallelism  between  the  Triassic  areas  and  the  Appalachian 
chain  is  one  of  the  great  facts  to  be  here  noted.  It  is  well  seen  on  the  map, 
page  412,  and  for  Pennsylvania  on  that  of  page  730.  The  general  parallel- 
ism between  the  strike  of  the  upturned  beds  and  the  same  course  —  that  is, 
the  trend  of  the  areas  —  is  another  important  fact.  The  two  are  satisfactory 
evidence  that  the  agency  concerned  over  the  Atlantic  border  was  the  same 
for  Jurassic  time,  as  for  the  epoch  when  the  Appalachians  were  made ;  and, 
it  may  be  added,  for  all  epochs  of  Eastern  Border  mountain-making. 

In  the  Connecticut  valley  area  there  was  an  eastward  dip  also  in  the 
fracture  planes,  and  a  westward  upthrust  along  these  planes ;  and  this  also 
was  a  feature  of  the  Appalachian  upturning.  These  facts  imply  the  action 
of  lateral  pressure  from  the  eastward,  or  the  direction  of  the  ocean. 

In  the  Palisade  area  passing  from  New  York  through  New  Jersey  and 
Pennsylvania  into  Virginia,  and  in  the  western  areas  of  Virginia  and  North 
Carolina,  the  results  of  the  upturning  are  in  general  the  reverse  of  those  in 
the  Connecticut  valley  and  in  eastern  North  Carolina.  The  beds  of  sandstone 
and  the  great  fracture-planes,  for  the  most  part,  dip  westward  or  northwest- 
ward, and  the  upthrust  along  the  fracture-planes  was  southeastward. 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  799 

In  Connecticut,  the  sandstone  beds  almost  invariably  dip  eastward. 
In  Virginia,  in  the  Richmond  area,  which  is  one  of  the  easternmost,  the  beds 
have  a  synclinal  structure,  the  rocks  on  the  east  side  dipping  northwestward, 
and  those  on  the  west  side,  southeastward  (Fontaine).  In  the  eastern  Deep 
River  area  of  North  Carolina  the  dip  averages  20°  southeastward,  but  varies 
from  10°  to  35°  (Fontaine). 

Notwithstanding  the  diversity  between  the  orographic  features  of  the 
more  western  and  the  eastern  belts,  the  intimate  relation  to  the  Appalachian 
system  as  regards  method  of  upturning  of  the  former  as  well  as  of  the  latter 
cannot  be  questioned.  The  opposition  of  direction  in  dip  is  connected  with 
opposition  in  all  other  structural  features  in  the  two  ranges  of  belts,  and 
eminently  so  in  the  topography. 

The  opposition  in  dip  between  the  Connecticut  valley  and  the  Palisade 
area  has  been  explained  by  supposing  that  the  sandstone  was  made  in  waters 
that  spread  over  the  intervening  region,  and  that  an  actual  anticline  was 
produced  by  an  uplift.  But  only  marine  waters  could  have  covered  the  wide 
region  after  great  subsidences ;  and  to  this  idea,  all  the  facts  as  to  the  fresh- 
water origin  of  the  beds  by  fluvial,  lacustrine,  or  estuary  agency  are  opposed. 
Moreover,  the  Connecticut  valley  area  is  wholly  in  latitudes  more  northern 
than  the  Palisade. 

This  reversed  condition,  so  marked  in  the  results  over  the  two  areas, 
simply  implies  reverse  action  in  the  forces  concerned.  In  the  Palisade  region, 
accordingly,  the  lateral  pressure  was  from  the  westward;  thus  came  the 
reversed  dip  and  reversed  fault -planes  and  faulting.  On  this  view  of  the 
action  along  the  two  belts, —  that  is,  the  lateral  thrust  from  the  eastward  for 
the  eastern,  and  from  the  westward  for  the  western, — the  pressure  was  such  as 
would  tend  to  make,  or  actually  did  make,  a  geanticline  between  two  extended 
lines,  an  eastern  and  a  western.  But  upturnings  of  beds  took  place  only 
where  there  had  been  geosynclines  of  deposition,  that  is,  in  the  Triassic  areas. 

The  effective  upturning  force  acted  alike  from  opposite  directions,  the 
eastern,  or  oceanward,  and  the  western,  or  landward  ;  while  in  the  Appalach- 
ians its  action  was  from  the  eastward  chiefly ;  but,  still,  like  the  Appalachian 
Range  as  a  whole,  each  of  the  several  areas  is  inequilateral  in  orogenic  struc- 
ture. The  Connecticut  valley  area  tapers  out,  both  as  to  width  and  depth  of 
deposits,  at  New  Haven  Bay  on  the  Sound.  There  is  no  trace  of  the  trough 
over  Long  Island.  It  is  possible  that  in  the  direction  of  this  eastern  Triassic 
line  a  sandstone  area  existed  over  the  shallow-water  border  of  the  Atlantic, 
south  of  Long  Island  and  east  of  New  Jersey;  but  no  proof  of  this  has  been 
observed.  In  the  Richmond  area  of  eastern  Virginia,  however,  and  in  the 
Deep  River  area  of  North  Carolina,  as  the  dip  of  the  beds  of  each  proves,  the 
true  continuation  is  found,  for  these  areas  have  the  same  position  relatively 
to  the  western  areas  of  those  states,  as  the  Connecticut  valley  area  has  to 
the  Palisade  area.  The  map  on  page  412  illustrates  the  fact,  not  only 
that  these  areas  mark  out  the  position  of  the  eastern  side  of  the  series  of 
Triassic  belts,  but  also  that  it  is  parallel  to  its  axial  line. 


800  HISTORICAL   GEOLOGY. 

In  the  progress  of  the  upturning  the  sandstone  was  variously  fractured 
and  faulted ;  and  the  masses  into  which  it  was  thus  divided  were  in  part 
forced  over  one  another,  and  up  whatever  surfaces  lay  beyond,  and  thus  the 
monoclinal  structure  was  produced.  The  abraded  surfaces  of  the  beds, 
extensively  exhibited  in  some  regions,  indicate  that  there  was  a  vast  amount 
of  intestinal  movement  as  well  as  ordinary  faulting.  The  sandstone  should 
therefore  have  acquired  its  greatest  thickness,  from  piling  on  itself,  on  the 
side  of  the  area  in  the  direction  of  the  movement ;  that  is,  on  the  west  side 
in  the  Connecticut  valley,  and  on  the  east,  in  the  Palisade  belt.  Moreover, 
the  confining  slope  of  the  trough  on  this  side  would  have  been  an  obstruc- 
tion that  would  have  there  increased  the  fracturing  and  the  amount  of  piling. 

The  lateral  thrust  would  have  narrowed  the  belt  of  deposits  of  each 
geosyncline.  The  amount  of  narrowing,  taking  the  mean  dip  of  the  beds  at 
15°,  and  supposing  no  modifying  conditions,  would  have  been  about  100  feet 
for  every  3000  feet  of  width.  But  the  piling  of  the  beds  referred  to  above, 
and  the  shoving  of  the  beds  beyond  the  limit  of  the  original  area  or  trough, 
are  modifying  conditions  that  cannot  be  estimated. 

The  shallow  mass  of  deposits  in  each  geosyncline  had  a  temperature  at 
bottom  possibly  of  200°  F.  or  300°  F. ;  for,  if  10,000  feet  thick,  the  present 
rate  of  increase  in  temperature  downward  would  make  the  maximum  only 
200°  F.  This  temperature  was  sufficient  only  for  a  partial  consolidation  of 
the  beds  through  any  siliceous  waters  that  might  have  been  made,  and  for 
the  reddening  of  them  by  the  oxidation  of  any  iron  present.  The  movements 
from  lateral  pressure  against  the  trough  in  the  earth's  crust,  in  which  the 
beds  lay,  might  have  produced  their  results  by  molecular  transfer  in  the 
mass  of  the  crust.  But  the  facts  point  unquestionably  to  great  and  deep 
fractures.  The  directions  of  such  fracture-planes  would  have  been  deter, 
mined  partly  by  the  positions  of  the  weaker  planes  in  the  rocks  beneath. 
Such  weak  planes  may  be  due  to  kinds  of  rocks;  to  the  foliation  or  bedding 
of  the  rocks ;  to  earlier  fault-planes ;  or  to  preexisting  mountain  features  of 
the  Atlantic  border.  But  their  actual  positions  are  not  often  determinable 
except  so  far  as  they  may  be  inferred  from  the  lines  of  eruptive  rocks. 

Igneous  eruptions  over  the  Triassic  areas. — The  general  features  of  the 
outcrops  of  trap  over  the  areas  are  well  displayed  in  the  Connecticut  valley, 
an  excellent  map  of  which  for  the  state  of  Connecticut  is  contained  in 
J.  G.  Percival's  Geological  Report  (1842)  ;  and  for  the  Massachusetts  portion, 
by  B.  K.  Emerson,  in  the  Bulletin  of  the  Geological  Society  of  America  for 
1891.  The  accompanying  map,  Fig.  1346,  which  is  part  of  Percival's,  embraces 
the  southern  three  fifths  of  the  whole  area  in  Connecticut,  or  the  part  from 
the  Sound  to  the  latitude  of  Hartford.  Its  length  is  37  miles,  or  about 
one  third  of  that  of  the  whole  valley. 

On  the  map  the  dotted  lines  nn,  mm  mark  the  outlines  of  the  Triassic  area ;  outside, 
both  to  the  east  and  west,  the  rocks  are  crystalline  rocks.  The  heavy  black  lines  rep- 
resent the  outcrops  of  trap.  Commencing  at  the  south,  the  abbreviations  used  on  it  are 
as  follows :  N  H,  New  Haven  ;  pp,  6&,  dikes  of  trap  outside  of  the  area,  on  the  west ;  and 


MESOZOIC   TIME  —  TRIASSIC   AND  JURASSIC. 
1346. 


801 


Map  of  part  of  the  Triassic  area  of  central  Connecticut.    J.  G.  PercivaL 
DANA'S  MANUAL  —  51 


802  HISTORICAL  GEOLOGY. 

ee,  another  on  the  east ;  S,  Saltonstall  Ridge,  called  Pond  Ridge  by  Percival ;  T  T, 
Totoket  Ridge  ;  C,  Mount  Carmel ;  M,  Meriden  ;  Mt,  Middletown ;  Pd,  Portland  and 
Portland  sandstone  quarries ;  H,  Hartford.  The  scale  of  the  map  is  ^  of  an  inch  to  5 
miles.  The  many  interruptions  in  the  lines  of  trap  on  Percival' s  map  are  generally  due 
to  intervals  of  sandstone,  and  the  smaller  of  them  may  often  have  resulted  from  falls  of 
the  sandstone  walls  of  oblique  fissures,  as  explained  on  page  298.  But  in  some  cases  they 
are  breaks  in  the  outcrop  of  trap  in  which  no  sandstone  was  in  view,  and  where  further  in- 
vestigation may  prove  the  line  to  be  continuous.  One  such  case  exists  in  the  termination 
of  West  Rock,  and  another  in  the  south  side  of  the  summit  of  Mount  Carmel ;  and  changes 
have  been  made  correspondingly  in  Percival's  map.  One  other  change  made,  in  order  to 
represent  the  results  of  later  observation,  is  the  continuation  of  the  dike  bb  to  and  across 
West  Rock. 

Some  of  the  general  facts  of  importance  illustrated  on  the  map  are  the 
following :  — 

1.  The  outcrops  are  most  numerous  in  this  southern  portion  of  the  area. 
To  the  north  of  the  region  here  mapped,  there  are  only  continuations -of 
the  three  western  lines  to  Mount  Tom  and  Mount  Holyoke  in  Massachusetts, 
and  an  isolated  line  farther  north  which  passes  near  Greenfield. 

2.  The  outcrops  of  trap  are  not  wholly  confined  to  the   Triassic  area. 
Two  lines  of  dikes  exist  on  the  west  side  (pp,  bb,  on  the  map) ;  they  con- 
tinue southwestward  to  the  Sound.     In  one  of  them,  the  trap  is  sparsely 
porphyritic  with  crystals  of  anorthite.     There  are  also  two  long  dikes  on 
the  east :  one,  commencing  in  ee,  to  the  eastward  of  New  Haven,  not  a  mile 
distant  from  the  area,  has  a  course  nearly  parallel  to  its  eastern   outline 
for  10  miles,  but  afterward  diverges  from  it ;  the  other  commencing  nearly 
east  of  Hartford,  just  outside  of  the  area,  is  parallel  to  the  area  for   the 
same  distance.     Both  were  traced  by  Percival  to  the  Massachusetts  line. 

The  convergence  of  the  dike  ee,  southwestward  toward  New  Haven  Bay, 
and  that  of  the  other  lines  of  trap  in  the  Triassic  area,  are  part  of  the 
evidence  that  the  estuary  or  trough  terminated  at  this  place. 

3.  The  trap  (doleryte  or  diabase)  is  essentially  the  same  rock  in  all  the 
belts,  and  through  all   the    Triassic    areas.     It    is    sparingly   chrysolitic, 
according  to  Iddings,   in    Orange,   N.  J.,  and   rarely   so   in   other   places. 
The  chief  variation  is  a  result  of  alteration  by  means  of  water  imbibed  as 
vapor,  when,  it  is  believed,  the  rock  was  on  its  way  through  the  sandstone  to 
the  surface.     The  rocks  are  sometimes  unaltered  on  one  side  of  a  belt,  and 
much  altered  along  its  middle  or  on  the  other  side.     Dikes  intersecting  the 
outside  crystalline  rocks  are  wholly  free  from  the  alteration,  showing  that  the 
moisture  was  not  from  the  same  source  as  the  trap,  but  more  superficial.     The 
altered  hydrated  trap  has  little  luster ;  is  often  amygdaloidal  within  50  feet 
or  so  of  the  surface ;  and  decomposes  rapidly,  and  often  to  a  depth  of  several 
yards,  so  that  a  small  dike  between  layers  of  sandstone  is  sometimes  found 
wholly  changed  to  a  brownish  yellow  earth,  and  looks  like  a  bed  of  tufa. 
Fot  remarks  on  amygdaloids,  see  pages  78,  336.     Along  some  of  the  fissures 
there  were  carried  up  with  the  trap  ores  of  copper,  and  thus  copper  veins 
were  made  in  the  trap  and  in  the  sandstone  of  the  vicinity  (page  338). 


MESOZOIC    TIME  —  TRIASSIC    AND   JURASSIC.  803 

4.  The  lines  of  trap  on  the  map  are  usually  curved,  with  the  convexities 
to  the  west ;  or  they  consist  of  a  series  of  similar  curves.     Some  are  bow- 
shaped  with  hooked  ends.     Saltonstall  Ridge  at  S,  on  the  east  side  of  Salton- 
stall  Lake,  near  the  Sound,  is  a  marked  example  of  the  bow-shaped  outcrop. 
So  also  is  the  narrow  line  just  east  of  it,  and  another  broader  and  larger  line 
to  the  northeast,  the  Totoket  Eidge,  T  T.     The  Mount  Tom  Eidge  has  an 
eastward  bend,  hook-like,  at  its  southern  end,  in  the  Meriden  region,  and 
another  long  one  at  its  northern  •  end,  constituting  Mount  Holyoke.     The 
distance  between  the  two  hooked  ends  is  over  50  miles,  so  that  it  is  a  very 
long  bow.     West  Eock  Eidge  has  a  hook  at  its  southern  extremity,  and  a 
series  of  curves  in  its  course  to  the  north ;  but  it  terminates  northward  near 
where  the  Mount  Tom  Eidge  ends,  as  if  a  sequel  to  the  latter  in  formation. 

These  features  are  so  general  that  they  seem  to  indicate  some  compre- 
hensive method  of  origin. 

5.  The  belts  are  for  the  most  part  approximately  parallel  to  the  axial 
line   of  the  area,  or  nearly  north-by-east  in  course.     But  there  are  many, 
exceptions,  especially  in  the  southern  part  of  the  area. 

The  large  north-and-south  outcropping  belts  of  trap  usually  have  bold 
features  over  the  landscapes.  This  prominence  is  owing  to  denudation  since 
the  time  of  the  eruption  of  the  trap,  for  originally  the  trap  was  probably  all 
under  the  cover  of  the  sandstone.  The  hard  igneous  rock  generally  makes 
the  summits  of  ridges.  The  slope  of  the  ridge  in  the  direction  of  the. dip  of 
the  sandstone  (eastward  in  the  Connecticut  valley)  is  usually  gradual,  and 
along  it  the  trap  disappears  beneath  overlying  sandstone ;  but  in  the  opposite 
direction,  the  ridge  has  a  bold  front  of  columnar  trap  resting  on  the  sand- 
stone. At  the  contact  with  the  trap,  in  a  north-and-south  ridge,  the  sandstone 
appears  to  be  horizontal,  because  its  dip  is  not  northward  or  southward,  but 
eastward.  Only  in  a  transverse  section  of  such  a  ridge  should  the  underlying 
sandstone  show  its  true  inclined  position.  These  facts  are  illustrated  in  the 
figures  on  page  302.  The  general  features  of  the  bold  trap  front  are  better 
shown  in  the  following  view  of  West  Eock ;  but  the  part  exposed  to  view  is 
an  east-and-west  section,  so  that  here  the  dip  of  the  sandstone  is  exhibited. 
Below  the  bold  columnar  front  of  such  ridges  there  is  usually  a  talus  of 
broken  blocks  of  trap ;  the  removal  of  this  talus  (for  road  making)  has 
exposed  the  sandstone  to  view.  (The  nearly  horizontal  line  below  the  out- 
cropping sandstone  is  the  course  of  a  road.) 

The  Palisades  along  the  Hudson  are  another  good  example  of  a  trap  ridge.  The  bold 
front  of  the  Palisades  faces  eastward,  the  dip  of  the  sandstone  being  to  the  westward ; 
and  as  the  ridge  has  a  northward  course,  the  underlying  sandstone,  which  makes  about 
half  the  height  above  the  river's  level,  presents  a  nearly  horizontal  line  beneath  the  trap. 

The  east-and-west  outcrops  of  trap  are  generally  lines  of  simple  trap 
dikes;  that  is,  of  trap  within  the  fissure  up  which  it  flowed.  On  the  contrary, 
each  north-and-south  outcrop  in  almost  all  cases  is  that  of  an  outflow  of  trap 
from  a  supply  fissure,  which  is  situated  somewhere  to  the  eastward.  Examples 


804 


HISTORICAL  GEOLOGY. 


of  large  dikes,  180  to  300  feet  wide,  are  shown  in  Pine  Rock  and  Mill  Bock, 
on  the  map  on  page  299.  Smaller  dikes  are  very  common  in  many  localities. 
The  West  Rock  Ridge,  Mount  Tom  Ridge,  and  Saltonstall  Ridge  afford 
examples  of  outflow  masses  or  sheets.  With  regard  to  the  West  Rock  trap- 
mass  it  is  proved,  on  page  302,  that  it  is  a  laccolith ;  that  the  eruptive  rock, 
coming  up  from  below,  was  forced  into  a  space  opened  by  itself  between 
layers  of  the  sandstone,  and  there  it  accumulated  under  the  weight  of  the 
superincumbent  sandstone, — probably  one  or  more  thousands  of  feet  thick. 
It  is  also  shown  that  the  upturned  sandstone  underneath  the  outflow,  Fig. 
1347,  was  profoundly  abraded  by  the  forced  movement,  over  it,  of  the  melted 

1347. 


View  of  the  south  front  of  West  Eock,  near  New  Haven,  Conn.,  showing  the  columnar  trap  and  the 

sandstone  underneath  it. 

rock,  and  thereby  reduced  to  a  nearly  horizontal  surface.  No  earth  or  stones 
intervene  between  the  trap  and  sandstone  in  the  section  exhibited,  showing 
that  the  material  removed  by  abrasion  was  pushed  on  and  lodged  elsewhere ; 
and  also  proving  that  the  flow  was  not  surficial,  inasmuch  as  all  surface 
earth  or  debris  is  absent.  It  has  been  shown,  besides,  that  East  Rock,  near 
New  Haven,  is  laccolithic ;  and  so  also  the  trap  belt  next  west  of  the  Salton- 
stall Ridge,  and  the  second  trap  belt  east  of  the  same,  as  described  by  E.  0. 
Hovey.  In  addition,  the  trap  rests,  in  each  case,  on  upturned  sandstone, 
proving  that  the  upturning  was  a  previous  event  for  the  region.  It  follows, 
therefore,  that  the  trap  of  the  intervening  Saltonstall  Ridge  must  be  similar 
in  mode  of  origin  and  time  of  eruption. 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC. 


805 


1348. 


Ts 


efeet. 

Trap  bluff  at  Greenfield,  Mass.,  with 
breccia  of  sandstone  blocks  (the 
part  Tt  cemented  by  trap,  and  Ts 
by  sandstone)  lying  between  it  and 
the  sandstone  S.  B.  K.  Emerson, 
'92. 


While  the  West  Rock  section,  Fig.  1347,  indicates,  not  only  a  great 
amount  of  abrasion,  but  also  a  shoving  forward  of  the  abraded  material 
beyond  or  west  of  the  place  in  view,  that  of  the  second  trap  belt  east  of  the 
Saltonstall  Ridge  has  the  abraded  material 
resting  on  the  underlying  sandstone  in  the 
form  of  rounded  and  angular  stones  of  the  trap 
and  sandstone ;  the  accumulation  was  evidently 
made,  as  Hovey  states,  by  the  friction  between 
the  liquid  and  solid  rock. 

B.  K.  Emerson  reports  that  the  trap  sheet 
of  northern  Greenfield,  Mass.,  where  the  bluff 
or  trap  faces  westward  (the  dip  being  east- 
ward), as  shown  in  Fig.  1348,  rests  on  a  bed 
of  coarse  sandstone  breccia,  12  to  16  feet  thick, 
the  upper  part  of  which  (Tt)  is  cemented 
by  trap,  which  extends  from  above  between 
the  blocks,  and  the  lower  part,  6  or  8  feet 
thick  (Ts),  by  red  sand,  which  is  continu- 
ous with  the  underlying  sandstone.  More- 
over, the  bed  of  trap  breccia  rests  on  unbaked 
sandstone.  At  a  locality  in  the  Mount  Tom 
Eidge,  in  the  town  of  Holyoke,  the  base  of  the 
trap,  according  to  Emerson,  is  "  kneaded  full  of 
dove-colored  limestone,"  looking  uas  if  the  limestone  and  trap  had  been 
plastic  at  the  same  time  "  ;  and  at  one  place,  where  the  trap  is  about  300 
feet  thick,  its  "  upper  surface  is  filled  in  the  same  way  with  the  same  lime- 
stone to  a  depth  of  8  or  10  feet."  The  limestone  had  been  torn  off  from  a 
layer  not  visible  in  the  section ;  for,  as  he  says,  only  sandstone  is  there  in 
view,  or  was  found  in  a  boring  carried  down  3500  feet. 

The  large  north-and-south  belts  of  trap  often  have  an  attendant  belt  on 
the  east  or  west  side,  or  on  both,  which  is  generally  made  of  hydrous  and 
amygdaloidal  trap,  even  when  the  trap  of  the  large  belt  is  of  the  normal 
anhydrous  kind.  Percival  draws  special  attention  to  this  feature.  The 
Mount  Tom  Ridge  is  thus  attended,  as  the  map  on  page  801  shows,  from 
the  Meriden  region  northward ;  the  line,  which  is  low  from  denudation,  is 
on  the  western  side  through  the  southern  part  of  the  Mount  Tom  Ridge, 
and  on  the  eastern  side  for  the  more  northern  part.  Saltonstall  Ridge  has 
a  similar  parallel  belt  to  the  east,  and  another  to  the  west  of  it,  only  a  few 
hundred  yards  distant,  and  each  is  perhaps  of  like  relations  to  the  "attendant" 
dike  of  the  Mount  Tom  Ridge. 

The  time  of  the  eruptions  and  their  relation  to  the  upturning  of  the  sand- 
stone. —  The  evidence  is  complete  that  eruptions  of  trap  preceded,  as  held 
by  Emerson  and  Davis,  the  deposition  of  part  of  the  sandstone.  The  sand- 
stone of  East  Haven,  east  of  Saltonstall  Ridge,  contains  stones  of  trap  at 
many  places,  as  described  by  E.  O.  Hovey,  while  none  are  known  to  occur 


806  HISTORICAL   GEOLOGY. 

over  the  region  west  of  the  ridge.  It  follows  therefore  that  the  eruptive 
work  began  before  the  close  of  the  period  of  the  sandstone  formation. 

But  it  appears  to  be  also  true  that  it  characterized  the  closing  part  of  the 
period.  The  facts  from  West  Rock,  and  others  of  similar  import  from  East 
Haven,  where  the  trap  rests  on  upturned  sandstone,  are  evidence  that  so  far 
as  these  regions  are  concerned,  the  upturning  preceded  the  eruptions.  This 
conclusion  involves  the  Saltonstall  region ;  and  if  this,  so  also  the  Totoket 
Ridge  and  others  to  the  north,  since  all  are  closely  alike,  and  in  close  con- 
junction. Moreover,  a  laccolithic  origin  may  be  inferred  not  only  for  East 
and  West  Rock,  but  for  all  such  cases. 

With  regard  to  the  Mount  Tom  Ridge,  direct  evidence  of  age  of  eruption 
is  wanting ;  for  no  east-and-west  sections  have  been  reported.  But  a  lacco- 
lithic origin  and  the  abrasion  of  the  underlying  sandstone  are  indicated  by 
the  occurrence  of  breccia  beneath  the  trap,  and  especially  by  the  limestone 
chips  in  the  lower  part  of  the  mass  of  the  trap,  and  also  over  its  upper 
surface,  as  described  by  Emerson.  A  bed  of  limestone  was  evidently  divided 
by  the  advancing  tongue  of  melted  trap,  part  being  left  below,  and  the  rest 
above.  As  Emerson  observes,  the  facts  prove  that  the  heavy  trap  flowed 
over  the  sandstone,  abrading  and  tearing  it.  But  they  prove  also  that  the 
flow  was  not  surficial,  but  laccolithic ;  for  in  the  case  of  an  advancing  surficial 
stream  the  lava,  being  retarded  by  friction  at  bottom,  has  a  downward  flow 
at  the  front,  and  hence  could  not  bear  to  its  upper  surface  material  met  with 
along  its  track. 

A  laccolithic  origin  for  the  Mount  Tom  Ridge  explains  also  the  existence 
of  the  attendant  dike  parallel  with  its  southern,  western,  or  eastern  side,  and 
for  similar  cases  elsewhere.  For  whenever,  in  the  forced  flow  of  lava  from 
the  supply  fissure  to  make  the  laccolith,  the  force  could  not  so  easily  con- 
tribute to  the  laccolithic  mass  (owing  to  the  weight  it  had  acquired  by 
accumulation  and  that  of  the  overlying  sandstone,  and  to  resistance  from 
other  sources)  as  make  a  fracture  either  side  for  a  new  place  of  escape,  the 
latter  event  would  take  place.  A  dike  of  five  inches,  which  is  visible  under 
the  trap  mass  in  the  south  front  of  West  Rock,  and  which  is  both  amygda- 
loidal  and  chrysolitic,  is  probably  an  example  of  this  mode  of  origin. 

This  evidence  of  a  laccolithic  origin  brings  the  north-and-south  trap  belts 
into  the  same  category,  as  to  method  and  time  of  origin,  with  West  Rock 
and  East  Rock.  After  or  during  the  upturning  of  the  sandstone  appears, 
therefore,  to  be  the  time  of  origin  of  the  larger  part  of  the  eruptions. 

The  hypothesis  has  been  brought  forward  by  W.  M.  Davis  (U.  S.  G-.  8.  Sep.,  vol. 
vii.,  and  elsewhere),  that  the  larger  part  of  the  trap  was  erupted  in  the  early  part  of  the 
Triassic  period  long  before  the  upturning;  that  in  the  case  of  the  Connecticut  valley 
area,  the  trap  was  poured  out  surficially  from  fissures  along  the  eastern  margin  of  the 
area,  and  thence  flowed  westward  across  it  over  the  underlying  sandstone  ;  that  after  more 
sandstone  had  been  deposited  a  second  and  larger  surficial  flow  took  place ;  then  after 
more  deposition  of  sand-beds  a  third  smaller  flow  ;  and  that  this  interstratified  sandstone 
and  trap  were  covered  by  other  horizontal  deposits  of  sandstone  of  great  thickness  ;  that, 


MESOZ01C   TIME  —  TRIASSIC   AND  JURASSIC.  807 

finally,  at  the  time  of  upturning,  the  trap  and  sandstone,  thus  interstratified,  were  forced 
up  into  monoclines,  which  by  denudation  became  the  existing  trap  ridges. 

According  to  the  views  already  presented,  (1)  the  trap  mass  in  the  trap  ridges  may  be 
conformable,  or  not,  to  the  associated  sandstone  ;  and  (2)  the  supply  fissure  was  near  the 
eastern  base  of  the  ridges,  or  not  far  distant.  These  conditions  are  illustrated  in  Figs. 
275,  276,  on  page  302.  In  the  views  of  W.  M.  Davis,  on  the  contrary,  (1)  the  trap  mass 
of  the  ridges  is  conformable  with  the  sandstone  and  with  its  other  trap  sheets  ;  and  (2)  it 
extends  to  the  east  and  west  of  the  ridges  as  a  conformable  sheet  in  the  sandstone  forma- 
tion, and  should  be  found  there  by  boring  if  not  exposed  at  surface. 

It  is  favorable  to  this  hypothesis  that  the  sandstone  is  admitted  to  be  in  monoclines ; 
that  the  trap  ridges  look  like  monoclines,  the  trap  and  sandstone  so  far  as  exposed  to 
view  being  eastward  in  dip  ;  that  the  greater  trap  belt  and  the  smaller  attendant  belt  on 
the  east  and  west  have  the  positions  in  the  external  view  that  correspond  to  layers  in  a 
monocline ;  that  in  some  regions  the  beds  of  the  sandstone  formation  underneath  the 
columnar  trap  in  the  front  of  trap  ridges  have  a  like  order  of  succession. 

But  it  is  unfavorable  to  it  that  the  hooked  or  bow-like  shapes  among  the  ridges  are  not 
such  as  are  characteristic  of  monoclinal  regions ;  that  the  varying  dip  of  the  sandstone 
within  the  bow  —  it  being  nearly  at  right  angles  to  the  direction  of  its  sides  and  ends  — 
is  an  exceptional  feature  for  monoclines,  and  an  actual  feature  of  those  trap  ridges  which 
are  admitted  by  all  to  be  eruptive.  It  is  also  unfavorable  that  no  outcrops  of  either  of  the 
three  conformable  sheets  of  trap  have  been  observed  along  the  eastern  margin  of  the  area  ; 
that  no  sections  of  the  sandstone  formation  occur  anywhere  in  the  part  of  the  area  east 
of  the  Connecticut  River,  which  exhibit  the  conformability  of  the  trap  sheets  with  one 
another  or  with  the  sandstone,  or  that  show  any  trap  at  all ;  that  no  sections  exhibiting 
conformability  have  been  observed  in  any  of  the  trap  ridges  themselves,  and  none  over 
the  part  of  the  Triassic  area  west  of  these  ridges.  Thus  positive  evidence  in  favor  of  the 
hypothesis  fails  ;  and  there  is  the  evidence  against  it  that  the  Saltonstall  region,  instead  of 
exemplifying  it,  as  claimed  by  its  author,  is  a  region  of  eruptions  after  the  upturning 
of  the  sandstone,  and  that  the  Mount  Tom  Ridge  bears  the  strongest  evidence  of  a 
laccolithic  origin. 

The  existence  of  buried  volcanoes  at  Mount  Carmel  (740'  high),  9  miles  north  of  New 
Haven,  has  been  announced.  But  there  is  no  evidence  of  the  "buried  volcanoes"  in 
sight :  neither  in  lava  streams,  volcanic  ashes,  nor  anything  else.  The  rocks  in  view  are 
the  ordinary  compact  trap  of  the  trap  dikes  of  the  region  and  the  intersected  granitic 
sandstone. 

Origin  of  the  eruptions. — Although  the  geosynclines  or  troughs  in  the 
earth's  supercrust  occupied  by  the  deposits  were  comparatively  shallow, 
none  probably  exceeding  in  depth  10,000  feet,  the  lateral  thrust  from  the 
opposing  directions  produced,  at  intervals,  fractures  and  movements,  if  not 
also  crushings,  at  considerable  depths  for  the  whole  length  of  the  Eastern 
Continental  border,  from  Nova  Scotia  to  southern  North  Carolina.  For, 
according  to  existing  theory,  the  region  of  fusion  was  where  the  earth's 
interior  temperature  was  so  near  the  fusing  point  of  the  rock,  that  the  heat 
from  dynamical  sources,  added  to  the  statical  heat  of  the  region,  would  produce 
fusion.  The  near  uniformity  in  the  kind  of  ejected  rock,  through  all  the 
Triassic  areas,  has  been  already  mentioned  as  other  evidence  that  the  fissures 
descended  below  the  supercrust  to  regions  where  basic  Archsean-like  rocks 
prevail.  The  ejection  of  rocks  of  the  basaltic  type  alone  may,  however,  be  a 
consequence  of  the  temperature  not  being  high  enough  to  melt  the  less  fusible 
rocks  containing  oligoclase  or  orthoclase. 


808  HISTORICAL   GEOLOGY. 

It  is  a  fact  deserving  especial  note  that  although  the  subterranean  fusion 
occurred  at  intervals  for  1000  miles,  the  fissures  by  which  ejections  took 
place  were  almost  wholly  confined  to  the  narrow  areas  of  the  Triassic 
geosynclines.  The  isolated  Southbury  area  of  Connecticut,  a  dozen  miles 
west  of  that  of  the  Connecticut  valley,  and  only  seven  by  two  and  one  half 
miles  in  area,  has  its  many  trap  dikes ;  and  none  exist  over  the  intervening 
region  or  to  the  north,  west,  or  south  of  it.  The  isolation  of  the  eruptions 
corresponds  with  that  of  the  upturning.  The  areas  of  the  geosynclines — that 
is,  of  subsidence  and  deposition — in  some  way  localized  the  areas  of  fractures 
and  fusion.  There  seems  to  be  good  reason,  in  the  facts,  for  locating  the 
chief  of  the  fractures  underneath  the  center  or  central  line  of  each  area 
and  under  that  half  of  it  which  is  nearest  to  the  general  axial  line  of 
the  chain  of  areas,  rather  than  underneath  the  outer  margin  of  the  other 
half,  or  in  any  part  of  this  half ;  that  is,  in  the  Connecticut  valley  area,  as 
Percival's  map  illustrates,  for  locating  it  underneath  its  central  line  and  the 
half  to  the  westward,  rather  than  underneath  the  eastern  part. 

There  are,  however,  two  long  dikes  just  east  of  this  Triassic  area, 
besides  two  others  to  the  west  of  it.  One  of  the  southwestern  of  these  out- 
side dikes,  bb  on  the  map,  is  proved,  by  its  cutting  through  the  West  Rock 
trap,  to  have  been  of  subsequent  origin ;  and  this  is  probably  true  of  all  four. 
The  four  are  alike,  moreover,  in  having  a  mean  course  of  N.  25°-30°  E.,  thus 
differing  about  15°  in  easting  from  the  average  course  of  the  trap  belts  in 
the  Connecticut  valley.  Similar  facts  are  afforded  by  the  region  of  the  Pali- 
sade Range.  They  accord  with  the  idea  that  these  outside  dikes  were 
erupted  when  the  orogenic  catastrophe  was  near  its  close,  and  the  localizing 
geosynclinal  conditions  had  lost  part  of  their  influence.  Perhaps  tension 
from  a  decline  in  the  lateral  thrust,  or  from  a  dissipation  of  the  subterranean 
heat  generated  by  the  movement,  led  to  these  divergent  lines  of  fracture 
and  eruption. 

According  to  J.  J.  Stevenson,  great  displacements  have  been  produced 
in  the  faulted  Appalachian  region  of  northwest  Virginia  at  some  time 
subsequent  to  the  origin  of  the  range;  and  it  is  probable  that  the  epoch 
was  coincident  with  that  of  the  Triassic  upturning.  ( Am.  Jour.  Sc.,  xxxiii., 
262,  1887.) 

Movements  over  the  Eocky  Mountain  Region  and  the  Pacific  Border. 
Making  of  the  Sierra  Nevada. 

Along  from  Mexico  northward,  in  the  Rocky  Mountain  region,  thick 
Triassic  and  Jurassic  deposits  were  in  progress,  preparatory  for  future 
mountain-making ;  but,  in  general,  only  oscillations,  and  some  emergences  in 
the  general  course  of  geosynclinal  subsidence,  have  been  reported.  Over 
the  summit  region  of  the  Rocky  Mountains  deposition  was  continued  quietly, 
as  a  general  thing,  through  another  period,  the  Cretaceous,  before  any  great 
disturbance  took  place.  On  the  ground  of  the  absence  of  Liassic  beds  over 
the  region  south  of  Wyoming,  R.  C.  Hills  has  inferred  that  an  emergence 


MESOZOIC   TIME  —  TRIASSIC   AND   JURASSIC.  809 

there  took  place  after  the  Triassic.  In  the  Sierra  Nevada  an  unconformity 
occurs,  according  to  Diller,  between  the  Lias  and  Upper  Trias  of  the  Taylor- 
ville  region,  but  the  succession  of  deposits  shows  that  no  emergence  in  that 
portion  of  the  Sierra  Nevada  accompanied  the  disturbance.  In  the  Island 
belt  of  British  Columbia,  along  Vancouver  and  the  Queen  Charlotte  Islands,  an 
emergence  occurred  after  the  Triassic  period;  for  no  Jurassic  beds  exist 
between  the  Triassic  formation  of  the  region  and  the  Cretaceous ;  moreover, 
at  some  time  between  the  Triassic  period  and  the  Cretaceous,  according  to 
G.  M.  Dawson,  an  extensive  upturning  of  the  Triassic  beds  took  place;  but 
whether  at  the  close  of  the  Triassic  or  of  the  Jurassic  is  left  uncertain 
(1886,  1887). 

The  dose  of  the  Jurassic  period  was  the  time  of  the  making  of  the  Sierra 
Nevada  Eange,  as  announced  by  J.  D.  Whitney  in  1864  (Am.  Jour.  Sc., 
xxxviii.,  1864;  Rep.  Geol.,  1865),  after  the^  discovery  of  Triassic  and  Jurassic 
fossils  in  Plumas  County,  and  of  Jurassic  in  the  Auriferous  slates  of  Mariposa 
County  and  other  regions.  This  conclusion  has  been  questioned  and  the 
•event  referred  to  the  Middle  Cretaceous,  on  the  ground  chiefly  of  resemblance 
between  the  Aucellse  of  the  Jurassic  Sierra  slates  and  those  of  the  Lower 
Oetaceous ;  but  it  has  been  fully  confirmed  by  the  study  of  the  Mariposa 
and  other  fossils  by  Hyatt  and  others,  and  by  the  fact  of  the  unconform- 
ability  of  the  Lower  Cretaceous  with  the  rocks  of  the  Sierra  in  many  places 
west  of  the  Sacramento  River. 

It  is  also  sustained  by  the  fact  of  the  conformability  of  the  Lower  and 
Upper  Cretaceous,  or  the  Shasta  and  Chico  series,  as  observed  by  Diller; 
who  has,  moreover,  traced  the  imconformability,  not  only  along  the  west  side 
of  the  Sacramento,  from  Pit  River  southward  by  Bedding,  Horsetown,  and 
Ono,  into  Tehama  County,  but  also  northward  by  Yreka  and  Ashland,  far 
into  Oregon.  Moreover,  other  ranges  to  the  west  and  north  participated  in 
the  upturning;  for  the  Coast  Range  and  the  Klamath  Mountains  were 
parts  of  the  result,  according  to  Diller  and  Fairbanks ;  and  it  may  be  that 
still  others  in  the  Sierra  line,  to  the  north  or  south,  were  then  formed. 

The  black  slates  and  siliceous  rocks  of  the  auriferous  belt  of  the  Sierra 
are  associated  with  hydromica  schist,  hornblende  schist,  serpentine,  crystal- 
line limestone,  along  with  some  sandstone,  and  with  limestone  which  is 
semi-crystalline.  From  the  Mariposa  region  northward  they  commonly  have 
a  dip  eastward  of  60°  to  80°  or  90°.  The  relative  positions  of  the  rocks  of 
the  belt  are  finely  exhibited  on  the  colored  geological  maps  of  parts  of  the 
Sierra  region  published  by  the  United  States  Geological  Survey,  prepared 
chiefly  by  Lindgren  and  Turner.  They  show  by  colors  the  positions  of  the 
areas  of  outcrop  of  the  granite  or  dioryte,  which  makes  the  core  of  the  Sierra, 
and  also  of  the  various  eruptive  rocks  of  the  region  as  well  as  the  belts  which 
make  up  the  Auriferous  series. 

In  the  Taylorville  region,  Plumas  County,  the  beds,  ranging  from  Upper 
Jurassic  to  the  Silurian,  are  partly  in  overthrust  flexures,  the  thrust  being 
to  the  eastward  (landward)  as  described  and  figured  by  Diller  (G.  Soc.  Am., 


810  HISTORICAL   GEOLOGY. 

1892).  It  is  probable  that  there  were  ranges  of  flexures  and  monoclinal 
shoves  along  the  rest  of  the  Sierra  to  the  southward  and  great  upthrust  faults 
also  in  the  Taylorville  region.  . 

The  maximum  thickness  of  the  rock  in  the  Taylorville  region  is  24,500 
feet,  of  which  17,500  feet  are  Paleozoic  and  7000  feet  Mesozoic  (Diller). 
The  Sierra  Nevada  geosyncline  of  deposition,  which  began  during  or  before 
Upper  Silurian  time,  hence  reached  in  this  part  a  depth  nearly  of  25,000 
feet ;  this  was  the  thickness  of  the  pile  of  deposits  that  was  upturned  and 
flexed  in  the  crisis  of  mountain-making  at  the  close  of  the  Jurassic.  The 
heat  generated  by  the  movements  was  sufficient  for  the  rather  feeble  meta- 
morphism  which  characterizes  the  rocks.  Facts  also  appear  to  prove  that 
the  core  of  diorytic  granite,  which  is  the  chief  rock  of  the  ridge  to  the  south, 
was  an  Archaean  ridge  over  and  against  which  the  thrust  took  place  ;  for  the 
stratified  rocks,  where  in  contact  with  it,  show  in  some  places  in  their 
crystallization  or  metamorphism  the  effects  of  the  friction.  For  an  example 
of  such  effects,  see  page  534.  This  view  of  the  Archaean  age  of  the  Sierra 
core  of  granite  is  presented  by  King  in  his  40th  Parallel  Keport,  1878. 

The  Sierra  Nevada,  when  first  formed,  probably  had  not  half  its  present 
height.  It  has  a  later  history  of  great  geological  interest. 

The  formation  of  the  gold-bearing  veins  of  quartz  in  the  Sierra  rocks  was 
a  consequence  of  the  upturning.  The  wrenching  of  the  strata  opened  the 
leaves  of  the  slates,  and  also  made  great  intersecting  fissures.  The  opened 
spaces  and  fissures  became  filled  with  silica  (quartz)  which  the  heated  mois- 
ture took  into  solution,  and  also  with  such  ores  as  the  vapors  found  in  the 
beds.  Some  of  the  auriferous  quartz  veins  have  a  width  of  10  to  40  feet. 
As  the  modern  Sierra  gravels  contain  gold  from  the  rocks  which  make  the 
modern  Sierra,  so  the  more  ancient  rocks,  of  Jurassic  and  earlier  origin,  must 
have  held  gold  from  the  earlier  crystalline  rocks  of  the  Sierra;  and  this  gold, 
with  ores  of  lead,  copper,  and  other  metals,  the  hot  vapors  gathered  into  the- 
fissures.  It  was  not  the  work  of  superficial  waters  ;  for  the  veins  now  visible 
on  the  Mariposa  estate  and  elsewhere  are,  owing  to  denudation,  thousands  of 
feet  below  the  original  surface ;  but  there  is  no  doubt  that  superficial  waters 
took  part  in  the  work.  The  metamorphic  effects  include  many  rocks  in  the 
Coast  Range,  besides  prevailing  kinds  above  mentioned,  as  stated  on  page  318 ;, 
and  through  Becker's  studies  the  region  has  become  an  especially  instructive 
one  on  the  general  subject  of  metamorphism. 

The  "granite  core"  of  the  Sierra  constitutes  the  culminating  points  in  the  southern 
portion  of  the  range  —  among  them  Mount  Whitney,  which  has  a  height  of  14,898  feet 
above  sea  level;  and  it  is  the  rock  of  the  famous  Yosemite  Valley.  Whitney  states 
that  the  slates  near  the  granite  are  harder  than  at  a  distance  from  it,  and  contain  horn- 
blende ;  that  veins  of  granite  extend  into  the  altered  schists.  And  Diller  describes 
contact  phenomena  observed  by  him  in  the  Taylorville  region.  Moreover,  some  of  the 
auriferous  quartz  veins  extend  into  the  granite.  Evidence  of  this  kind  led  Whitney,  in 
his  California  Report,  to  present  the  view  of  the  post-Jurassic  age  of  the  granite  ;  and 
several  recent  investigators  of  the  region  hold  the  same  opinion.  But  intrusions  of 


MESOZOIC   TIME — TRIASSIC    AND   JURASSIC.  811 

dioryte  in  dikes  would  be  a  natural  result  of  friction  along  fault-planes  cutting  through 
such  an  underlying  crystalline  mass.  The  extrusion  of  igneous  rocks  accompanying 
mountain-making  has  been  a  common  fact  over  the  summit  region  of  the  Rocky 
Mountains  ;  an  example  occurs  in  the  Wasatch,  which  has,  like  the  Sierra,  a  "granite1* 
core. 

Had  the  granitoid  mass  been  a  result  of  deep-seated  eruption  at  the  time  of  the 
upturning,  or  at  any  later  date,  or  earlier,  it  would  have  come  to  the  surface  in  great 
fissures  ;  for  fissures,  as  the  result  of  fractures,  give  exit  to  the  confined  liquid  rock  of  the 
earth's  depths.  Moreover,  liquid  dioryte  is  identical  with  andesyte  lava,  and  liquid 
granite  with  rhyolyte ;  and  if  ejected  at  the  time  supposed,  it  should  show  evidence  of 
the  chilling  effect  of  the  relatively  cold  Sierra  rocks  along  their  contacts  with  them. 
Instead  of  this,  the  rock  of  the  core  is  well  crystallized  to  its  surface,  and  has  a  coarseness 
of  crystalline  texture  which  indicates  extremely  slow  cooling.  Neither  is  the  existence  of 
auriferous  quartz  veins  in  the  granite  positive  evidence  of  its  recent  origin  ;  for  the  granite 
of  Pike's  Peak,  according  to  W.  Cross,  contains  sandstone  dikes  (Feb.,  1894).  Further, 
if  the  ridges  of  crystalline  rock  in  California  and  to  the  north  are  all  eruptive  and  of  late 
Mesozoic  age,  as  is  urged,  and  the  emergence  at  the  close  of  the  Triassic  is  the  earliest  of 
much  importance,  there  is  no  sufficient  source  for  the  sediments  of  which  the  successive 
sedimentary  rocks  were  made.  They  could  not  have  come  from  the  eastward  ;  for  the 
oceanic  currents  of  the  Pacific  border  are  now,  and  must  have  been  in  early  time,  from  the 
northwest ;  and  besides,  the  ridges  of  the  Pacific  border  are  north  or  northwest  in  course. 
Moreover,  oceanic  currents  are  relatively  feeble  transporters,  and  find  their  material  for 
rock  making  near  at  hand. 

Such  a  mass  of  crystalline  rock  having  irregular  or  indefinite  outline  has  received  the 
name  of  bathylite.  (Bathylith  would  be  a  better  name,  as  it  is  here  used  for  a  mass,  not  a 
kind,  of  rock. )  It  has  one  mode  of  origin  that  is  consistent  with  indefiniteness  of  outline. 
When  a  pile  of  deposits,  30,000  feet  or  more  in  depth,  has  beds  in  its  lower  portion  that  admit 
of  fusion  under  the  action  of  the  heat  producing  metamorphism,  the  melted  material 
would  make  a  mass  of  indefinite  outline.  The  fusion,  under  the  same  circumstances,  of 
the  rocks  immediately  below  the  pile,  might  add  to  the  melted  mass  or  be  its  chief  source. 
Here  is  fusion  unbounded  by  the  walls  of  a  fissure.  This  was  common,  as  has  been  else- 
where remarked,  in  Archaean  time.  There  is  no  sufficient  evidence  that  it  occurred 
during  the  Sierra  upturning  at  the  close  of  the  Jurassic,  or  in  any  other  part  of  Mesozoic 
time. 

The  pre-Cretaceous  age  of  the  metamorphic  rocks  of  the  Coast  Eange 
has  been  urged  by  Fairbanks  (1892).  This  view  is  held  also  to  some  extent 
by  Turner  and  Diller ;  and  the  latter  states  that  the  Coast  Kange  was  up- 
heaved with  the  Sierra  Nevada  at  the  close  of  the  Jurassic.  This  conclusion 
is  drawn  from  the  fact  that  the  Cretaceous  thins  out,  both  to  the  eastward 
and  westward  of  the  Sacramento  valley,  and  that  the  later  beds  have  their 
greatest  extension  in  these  directions. 

The  Cascade  Eange  appears,  from  its  position,  to  be  part  of  the  Sierra 
system.  Becker  reports  that  the  same  class  of  metamorphic  rocks  characterizes 
the  portion  of  it  in  Oregon  where  not  buried  beneath  later  volcanic  ejections. 
The  Blue  Mountains  of  Oregon  also  have  their  Jurassic  rocks,  and  were 
probably  among  the  results  of  the  post- Jurassic  upturning. 

In  the  Plateau  Belt,  or  that  of  the  Great  Basin,  near  Carson  Lake,  the 
West-Humboldt  range,  according  to  King,  was  made  at  this  time.  It  includes 
several  ridges  between  1171°  W.  and  119°  W. ;  and  the  thickness  of  the 


812  HISTORICAL   GEOLOGY. 

Triassic  and  Jurassic  rocks  in  the  West-Humboldt  and  Pah-Ute  ridges  is 
stated  to  be  20,000  feet  or  more. 

The  Sierra  and  Wasatch  ranges  have  reverse  positions  with  reference  to 
the  Great  Basin.  Each  stands  with  its  steepest  side  and  its  high  shoulders 
toward  the  basin ;  and  in  each,  if  the  views  above  stated  with  reference  to  the 
Sierra  Nevada  are  correct,  this  bold  side  is  made  up  in  part  of  an  Archaean 
range,  which  was  really  the  protaxis  and  backbone  of  the  mountains. 

In  the  Vancouver  and  "Coast  Kanges"  of  British  Columbia  the  underlying  rocks 
-are  gray  granitoid  kinds,  containing  much  hornblende.  The  granite  of  the  latter  is 
associated  with  mica  schist  and  hornblende  schist.  In  the  former,  according  to  Dawson, 
the  granite  underneath  the  stratified  beds  of  the  Vancouver  Island  series  is  charged  with 
innumerable  darker  fragments  from  these  overlying  rocks  for  a  distance  inward  from  the 
surface  of  the  granite  in  some  places  of  a  few  hundred  feet  to  half  a  mile.  How  such  a 
penetration  of  fragments  from  the  non-metamorphic  beds  could  have  been  produced, 
Whether  the  granite  were  of  later  eruptive  origin,  or  of  earlier  production,  is  unexplained. 
If  the  granite  were  metamorphic  eruptive,  and  thereby  simultaneous  with  the  upturning 
in  its  eruption,  the  Vancouver  strata  would  have  been  distinctly  metamorphic. 

In  Europe,  through  the  Triassic  and  Jurassic  periods,  great  preparations 
in  rock  deposition  were  in  progress  over  deepening  troughs,  for  the  making 
of  the  Alps,  Pyrenees,  Carpathians,  Apennines ;  but  the  crisis  in  all  these 
cases  was  delayed  until  the  Tertiary. 

2.  CRETACEOUS  PERIOD. 

The  Cretaceous  period,  the  closing  part  of  the  "Age  of  Reptiles,"  is 
remarkable,  like  the  earlier  Mesozoic,  for  the  number  of  Ammonites  and 
Belemnites  among  its  marine  species;  for  the  diversity  and  size  of  the  Rep- 
tiles  populating  the  seas,  land,  and  air;  for  Birds  that  had  teeth  like  the 
Reptiles  ;  and  for  Marsupial  and  Oviparous  Mammals.  Unlike  the  earlier 
Mesozoic,  it  is  not  less  remarkable  for  the  existence  in  the  seas,  along  with 
Ganoids  and  Cestraciont  and  other  Sharks,  of  Teleost  Fishes,  related  to  the 
Perch,  Mackerel,  and  Salmon,  and  for  the  addition  to  the  forest  trees  of 
Angiosperms  of  kinds  related  to  the  Sassafras,  Magnolia,  Tulip  Tree,  Plan- 
tain, Fig,  Beech,  and  the  like,  together  with  Endogens  of  the  tribe  of  Palms. 

GENERAL  SUBDIVISIONS. 

Only  the  grander  subdivisions  of  the  Cretaceous  series,  the  LOWER  Cre- 
taceous and  the  UPPER,  or  the  EARLIER  and  LATER,  are  adopted  alike  in 
Europe  and  America.  But  it  is  not  yet  established  that  the  limits  between 
these  two  divisions  as  recognized  on  the  two  continents  are  the  same. 

NORTH    AMERICAN. 

1.    General  Geographical  Features  of  North  America. 

The  map  here  introduced  presents  a  general  idea  of  the  distribution  of 
land  and  salt  water  over  the  continent  of  North  America  during  the  period 


MESOZOIC   TIME CRETACEOUS.  813 

of  greatest  submergence  in  the  course  of  the  Cretaceous  period.  The  vertical 
lining  indicates  the  parts  that  were  submerged  during  the  Lower  Cretaceous  ;. 
the  horizontal  lining,  those  that  were  submerged  during  the  Upper  Creta- 
ceous ;  and  the  cross-lining,  the  areas  under  water  through  the  whole  period. 
The  map  is  too  small  for  an  indication  separately  of  the  fresh-water  Creta- 
ceous areas. 

1349. 


North  America  in  the  Cretaceous  period. 

The  positions  of  the  areas  of  Cretaceous  rock-making,  as  illustrated  for 
the  most  part  on  the  map,  are  the  following :  — 

1.  The  Atlantic  border. 

2.  The  Gulf  border  to  the  Mississippi  River. 

3.  The  Western  Gulf  border,  or  the  area  of  Texas  and  Mexico. 

4.  The  Western  Interior  Continental  Sea,  including  the  summit  region 
of  the  Rocky  Mountains,  and  extending  south  through  New  Mexico  and 
western  Texas  into  Mexico. 

5.  The  Pacific  border. 

Besides  these  there  are  the  independent  areas  of  Arctic  lands. 

The  submergence  reached  its  maximum  during  the  earlier  half  of  the 
Upper  Cretaceous.  During  the  progress  of  Lower  Cretaceous  time,  the  great 
Western  Interior  region  was,  for  the  most  part,  at  or  near  the  water  level ;  for 
the  outcropping  beds  are  fresh-water  or  marsh-made  formations.  Only  in 
its  southern  part  from  Kansas  over  Texas,  part  of  New  Mexico  and  Mexico, 
are  they  marine.  At  the  same  time  the  Atlantic  border  and  the  northern 
Gulf  border  had  their  fresh-water  formations.  But  after  the  Upper  Greta- 


814  HISTORICAL   GEOLOGY. 

ceous  period  had  made  some  progress,  the  waters  of  the  Mexican  Gulf 
began  to  spread  northward  over  the  subsiding  Continental  Interior ;  and 
before  its  earlier  half  had  passed,  the  submergence  had  reached  its  maximum. 
A  vast  Mediterranean  Sea  extended  from  the  inner  portion  of  the  Mexican 
Gulf,  probably  to  the  Arctic  Ocean.  The  Atlantic  border,  south  of  New  York, 
as  the  map  shows,  was  also  submerged,  and  a  wider  portion  of  the  Gulf 
border ;  and  along  the  valley  of  the  Mississippi  the  waters  stretched  north- 
ward beyond  the  present  mouth  of  the  Ohio,  making  a  great  Mississippi  Bay, 
which  was  100  miles  wide  in  the  latitude  of  Memphis.  But  in  Mexico,  at  this 
time,  the  large  Lower  Cretaceous  area  over  which  the  Atlantic  and  Pacific 
had  been  exchanging  waters,  was,  to  a  great  extent,  emerged.  Over  the 
Pacific  coast  region  there  was  a  narrow  strip  of  water  —  narrower  than  in 
Jurassic  time  because  of  the  making,  at  its  close,  of  the  Sierra  Nevada  and 
other  mountain  ranges  to  the  north. 

At  the  time  of  maximum  submergence  during  the  Upper  Cretaceous,  the 
American  Mediterranean  Sea  of  the  period  had  a  length,  if  extending  to  the 
Arctic  Ocean,  of  about  3000  miles.  The  decline  in  depth  and  size  began 
perhaps  by  the  middle  of  this  later  half  of  the  Cretaceous  period.  As 
explained  in  detail  beyond,  there  were  successively :  a  shallowing  of  the 
sea  and  an  emergence  of  dry  land  far  north  in  British  America,  cutting  off 
connection  with  the  Arctic  Ocean,  and  thus  converting  the  waters  on  the 
south  into  a  Mexican  Gulf,  2000  miles  or  more  in  length ;  a  contraction  of 
the  great  gulf  commencing  along  the  eastern  border ;  the  conversion  of  the 
gulf,  while  still  1500  miles  in  length,  into  a  region  of  alternating  brackish 
waters  and  fresh  waters  and  low  marsh-covered  lands,  situated  along  and  just 
east  of  what  is  now  the  Rocky  Mountain  section  of  the  Western  Continental 
Interior ;  the  disappearance  of  the  salt  waters,  leaving  only  fresh  waters ; 
and,  finally,  the  disappearance  of  these  waters  over  the  mountain  region, 
and  the  end  of  Cretaceous  deposition,  with  a  change  in  the  events  to  moun- 
tain-making. 

The  preceding  map,  illustrating  North  America  in  the  Cretaceous  period,  was  pre- 
pared for  this  work  chiefly  by  J.  S.  Diller  and  T.  W.  Stanton,  of  the  U.  S.  Geological  Survey, 
from  the  map  by  C.  A.  White  in  his  paper  On  the  Correlation  of  the  Cretaceous  (  U.  8. 
G.  S.  Bulletin,  No.  82,  1891),  and  from  those  for  British  America  by  G.  M.  Dawson  in  the 
Transactions  of  the  Royal  Society  of  Canada  for  1890,  and  largely  from  later  papers  since 
published,  and  more  recent  results  in  possession  of  the  U.  S.  Geological  Survey.  White's 
Bulletin,  which  contains  a  review  of  the  literature,  facts,  and  theories  pertaining  to  the 
North  American  Cretaceous  formation,  has  been  of  much  service  in  the  preparation  of  the 
following  pages. 

SUBDIVISIONS. 

No  general  subdivisions  of  either  the  Lower  or  Upper  Cretaceous  for  all 
the  regions  in  North  America  have  been  adopted,  on  account  of  the  wide 
diversity  of  the  regions  as  to  conditions.  Part  of  the  deposits  being  fresh 
water,  and  the  marine  fossils  of  the  Atlantic  and  Pacific  borders  and  of  the 


MESOZOIC   TIME  —  CRETACEOUS. 


815 


Atlantic  and  Continental  Interior  being  almost  completely  unlike,  it  has 
proved  very  difficult  to  determine  equivalency. 

The  Lower  Cretaceous  series  is  less  well  displayed  on  the  Atlantic  and 
Pacific  borders  than  in  Texas,  and  hence  the  division  into  epochs  has  been  based 
on  the  subdivisions  recognized  in  the  latter  region.  For  a  like  reason  the 
epochs  of  the  Upper  Cretaceous  are  based  on  the  subdivisions  over  the  Con- 
tinental Interior. 

The  principal  subdivisions  in  each  of  the  geographical  belts  are  given  in 
the  following  tables.  The  equivalency  indicated  is,  for  the  reasons  stated, 
largely  doubtful.  For  comparison,  the  corresponding  subdivisions  in  Euro- 
pean geology  are  presented  in  the  last  column. 

1.  LOWER  CRETACEOUS  DIVISION. 


Atlantic  and 
Northern  Gulf 
Borders 

Western  Gulf  Bor- 
der, Texas 

Rocky  Mountain 
Region 

Pacific  Border 

Europe 

3.  Gault  or  Albian 

1,    2,    3,  Potomac 
group,     Atlantic 
border  ;      Tusca- 

® 

1 

3.  WASHITA 
EPOCH 
2.  FREDERICKS- 

Horsetown 

2.  Aptian  or  Lower 
Greensand 
1 

loosa  group,  Ala.; 

a 

BURG  EPOCH 

| 

Eutaw  in  Miss. 

' 

1.  TRINITY 
EPOCH 

1.  Kootanie  Group 

Knoxville 

>1.  Neocomian 

2.  UPPER  CRETACEOUS  DIVISION. 


Atlantic 
Border 

Northern  Gulf 
Border 

Western  Gulf 
Border,  Tezas 

Continental  Interior 
and  Rocky  Mountain 
Region 

Pacific  Border 

Europe 

Unrepre- 
sented ? 

Laramie  in 

4.  LARAMIE  EPOCH 
2.  Upper  Laramie 

DANIAN 

Maestricht 

4-     Upper 

Unrepresented? 

western 

or 

beds 

Greensand 

Texas 

Denver  group 

in  part. 

1.  Lower  Laramie 

{Middle 

Eipley  group; 

f  2.  Glauconitic 

3.  MONTANA  EPOCH 

SENONIAN 

Greensand 

part  of  Rotten 

group 

2.  Fox  Hills  group 

_ 
Lower 

limestone 

j  1.  Ponderosa 

1.  Fort  Pierre  group 

Greensand 

[        marls 

Chico  group, 

Lower  part  of 

or  upper 

2.  Clay  marls? 

Rotten    lime- 

{2. Austin 

2.  COLORADO  EPOCH 

.     part  of  the 

TURONIAN 

stone.    Upper 

limestone 

2.  Niobrara  group 

Shasta- 

Eutaw    beds  ; 

1.  .Eagle  Ford 

1.  Benjton  group 

Chico  series 

Tombigbee 

shales 

1.  Raritan 

sands 

Lower  Cross- 

1.  DAKOTA  EPOCH 

CENOMANIAN 

group 

Timber  sands 

Dakota  group 

The  lower  limit  of  the  Cretaceous  series  in  North  America  has  been 
made  out  by  a  comparison  of  fossils  with  those  of  the  Neocomian  of  Europe. 
It  is  especially  marked,  in  most  localities  where  the  remains  of  plants  occur, 
by  the  presence  of  the  leaves  of  the  earliest  species  of  Angiosperms,  along 
with  those  of  the  still  abundant  Cycads.  As  at  present  understood,  the 


816  HISTORICAL   GEOLOGY. 

series  extends  as  far  upward  in  the  geological  formations  as  the  remains  of 
Mammals  are  of  the  oviparous  kinds,  with  none  of  the  ordinary  or  placental 
Mammals,  and  as  far  as  the  remains  of  Reptiles  include  the  Mesozoic  types 
of  Dinosaurs  and  Mosasaurs  ;  and,  moreover,  until  the  epoch  of  mountain- 
making,  which  closed  Mesozoic  time,  had  reached  its  climax.  No  marine 
fossils  of  the  Cretaceous  beds,  or  remains  of  Cretaceous  Vertebrates,  are 
positively  known  to  be  continued  from  the  Cretaceous  into  the  Tertiary 
formation. 

ROCKS— KINDS  AND  DISTRIBUTION. 
1.  LOWER  CRETACEOUS. 

Atlantic  border. —  The  Potomac  formation.  — The  Lower  Cretaceous  beds  of 
the  Atlantic  border  are  those  of  the  fresh-water  Potomac  formation,  so  named 
by  W.  J.  McGee  in  1888.  It  consists  mostly  of  granitic  sandstones  and  con- 
glomerates, loosely  aggregated  and  irregularly  bedded,  with  clay-beds  chiefly 
in  the  upper  portion.  It  occurs  on  the  Atlantic  border  near  the  inner  limit  of 
the  Cretaceous,  in  an  interrupted  belt,  passing  through  Delaware,  Maryland, 
the  District  of  Columbia,  Virginia,  and  beyond  to  Weldon  in  North  Carolina. 
The  thickness  is  600  feet  and  less.  The  width  of  the  belt  where  continuous 
is  seldom  over  10  miles ;  but  outliers  make  its  probable  original  width  in 
some  parts  perhaps  40  or  50  miles.  The  coarser  conglomerates  occur  in  the 
vicinity  of  the  larger  rivers,  the  Delaware,  Schuylkill,  Susquehanna,. 
Potomac,  and  James  River,  showing  that  the  rivers  had  then  their  place  over 
the  Atlantic  border,  and  also  that  their  floods  were  concerned  in  the  coarser 
deposition,  while  the  finer  materials  and  clays  mark  off  the  relatively  quiet 
areas  and  intervals.  The  presence  of  a  rare  marine  shell  shows  that  the  sea 
was  not  far  away.  The  granitic  material  is  that  of  the  rocks  over  much  of 
the  region  adjoining,  and  of  the  Triassic,  which  in  some  cases  they  overlie. 
But  the  other  sands  are  probable  evidence  that  the  drainage  over  the  Atlantic 
border  had  now  its  head  in  the  Appalachian  Mountains. 

According  to  Fontaine,  its  plants,  which  include  Cycad  stumps  and  leaves, 
Conifers,  and  Angiosperms,  range  in  types  through  the  whole  of  the  Lower 
Cretaceous  of  Europe,  and  include  some  species  that  are  related  to  those  of 
the  first  division  of  the  Upper  Cretaceous. 

According  to  L.  F.  Ward,  the  Cycad  stumps  occur  in  the  lower  part  of  the 
Potomac  group,  the  same  that  includes  the  Kappahannock  freestones.  He 
states,  also,  that  on  James  E/iver,  Virginia,  the  beds  contain  Cycads  and 
Sequoian  trunks  without  Angiosperms,  suggesting  the  idea  that  they  are 
perhaps  lower  in  the  series. 

Northern  Gulf  border.  —  The  Tuscaloosa  group  in  Alabama  —  so  named 
by  E.  A.  Smith  and  L.  C.  Johnson  —  consists  of  clay-beds  and  sand-beds, 
containing  impressions  of  leaves.  The  Eutaw  group,  in  Mississippi,  300  to 
400  feet  thick,  has  similar  characters,  and  contains  some  lignite  (Hilgard, 
1860). 


MESOZOIC   TIME  —  CRETACEOUS.  81V 

Western  Gulf  border.  —  In  Texas,  and  to  the  north  and  northeast  in 
Indian  Territory  and  Kansas,  west  and  northwest  in  New  Mexico,  and  west 
and  southwest  in  Mexico,  the  Lower  Cretaceous  beds  are  mainly  marine. 
They  are  the  Comanche  series  of  R.  T.  Hill.  They  have  fresh-water  beds  at 
bottom,  but  consist  above  largely  of  thick  limestones,  which  are  partly  chalk. 
They  abound  in  fossils,  and  indicate,  for  the  most  part,  the  presence  of  pure 
subtropical  oceanic  waters.  The  thickness  is  1000  to  2000  feet  in  central 
Texas,  and  5000  feet  on  the  Rio  Grande. 

The  subdivisions  adopted  by  Hill  (on  which  the  division  of  the  Lower 
Cretaceous  into  epochs  is  based)  are  as  follows :  — 

3.   WASHITA  EPOCH.  —  Washita  group. 
4.    Shoal  Creek  limestone. 
3.   Denison  beds,  sands,  clays,  limestones ;  Exogyra  arietina  clays. 

2.  Fort  Worthy  or  Washita,  limestone. 

1.  Preston  beds,  Duck  Creek  chalk,  Kiamitia  clays. 

2.    FREDERICKSBURG  EPOCH. — Fredericksburg  group. 

3.  Caprina  limestone,  Austin  marble. 

2.  Comanche  Peak  chalk. 

1.  Walnut  clays,  with   Exogyra  Texana  and  Gryphsea  Pitcher!  of 

Rcemer  (G.  mucronata  of  Gabb). 

1.    TRINITY  EPOCH.  —  Trinity  group. 

3.  Paluxy  sands. 

2.  Glen  Hose  beds,  sandy  below,  calcareous  above,  containing  marine 

fossils  and  some  vegetable  and  Reptilian  remains. 
1.    Trinity  sands,  with  fossil  leaves  and  lignite. 

As  above  indicated,  the  Cretaceous  limestones  of  Texas  are  partly  chalk, 
like  the  Cretaceous  of  southern  England ;  and  the  chalk  contains  flint.  Chalk, 
as  already  explained,  is  made  from  sea-bottom  accumulations  consisting 
largely  of  the  minute  shells  of  Rhizopods,  corresponding  to  the  Globigerina 
ooze  of  modern  seas ;  and  flint,  from  the  siliceous  spicules  of  sponges  and 
siliceous  shells  of  Diatoms  or  Radiolarians  that  may  exist  in  the  same  calca- 
reous deposits.  Chalk  is  supposed  to  show  therefore  that  the  seas  in  which 
it  was  formed  had  a  depth  of  at  least  some  hundreds  of  feet.  The  various 
fossils  in  the  beds  are  also  evidence  of  deep  water.  The  beds  continue  to  be 
thick  over  the  Indian  Territory,  but  thin  out  in  Kansas.  The  Ouachita 
Mountain  range  was  emerged  land,  and  the  Cretaceous  sea,  as  Hill  observes, 
had  a  shore  line  at  its  base. 

In  Mexico,  the  Lower  Cretaceous,  on  the  map  of  Castillo  (1891),  extends 
nearly  to  the  city  of  Mexico ;  and  it  is  continued  beyond  to  the  southward 
and  westward,  in  isolated  patches.  According  to  Hill  (1893),  all,  except  a 
small  portion  to  the  northeast,  is  a  continuation  of  the  Comanche  group  of 
Texas,  but  with  less  distinct  subdivisions ;  and  he  concludes  further  that 
DANA'S  MANUAL  —  52 


818  HISTORICAL   GEOLOGY. 

over  Mexico  during  this  time  the  Atlantic  and  Pacific  oceans  were  united. 
He  makes  the  thickness  20,000  feet. 

Rocky  Mountain  region  and  Central  Interior.  —  The  Lower  Cretaceous  of 
the  Rocky  Mountain  region  includes,  at  some  localities  at  base,  the  fresh-water 
Kootanie  beds  of  Dawson  (1885),  so  named  from  the  Kootanie  Pass,  in  the 
Rocky  Mountains,  about  30  miles  north  of  the  49th  parallel,  where  they  were 
first  found  and  characterized  by  their  fossil  plants.  The  beds  are  sandstones 
and  shales,  and  contain  some  coal.  Other  localities  occur  at  intervals  to  the 
northward  for  150  miles,  and  to  the  southward  in  western  Montana.  The 
beds  also  outcrop,  according  to  recent  determinations  by  L.  F.  Ward,  about 
the  Black  Hills,  in  western  Dakota,  where  they  have  a  thickness  of  200  to 
300  feet,  contain  trunks  of  Cycads  and  other  plants,  and  underlie  plant  beds 
of  the  Dakota  group  (Upper  Cretaceous)  to  which  they  had  been  referred. 
How  far  they  extend  eastward  and  southward  is  not  yet  ascertained.  In 
New  Mexico  they  are  mainly  marine  beds,  and  resemble  those  of  Texas,  with 
which  they  are  continuous. 

Pacific  border.  — The  Lower  Cretaceous  beds  of  the  Pacific  border  in  the 
United  States  are  marine,  but  in  British  Columbia  they  are  partly  of  fresh- 
water or  marsh  origin.  They  occur  (1)  in  the  Plateau  or  interior  region  of 
British  America,  and  (2)  along  the  Coast  belt. 

Over  the  Plateau  region  they  are  described  as  extending  over  Washington 
to  the  Yukon  district  and  northward  to  the  Arctic  Ocean  (G.  M.  Dawson). 
The  Plateau  region  within  the  United  States,  that  is,  the  Great  Basin,  was 
apparently  emerged;  but  south  in  Mexico,  as  already  described,  long  sub- 
mergence is  proved  by  the  existence  of  many  thousand  feet  in  thickness  of 
Lower  Cretaceous  beds. 

The  coast  region  has  a  border  of  Lower  Cretaceous  beds  along  the  greater 
part  of  California  and  Oregon,  and  also  on  Queen  Charlotte  Islands  and 
Vancouver  Island  ;  and  again  far  north  along  both  the  northern  and  southern 
shores  of  the  Alaskan  peninsula. 

The  beds  in  California  constitute  the  Shasta  group  of  J.  D.  Whitney 
(1869).  They  are  well  exposed  along  the  western  border  of  the  Sacramento 
valley,  where  they  are  divided  into  the  Knoxville  and  Horsetown  beds  — 
so  named  from  localities  in  the  region  by  C.  A.  White.  These  two  groups 
were  made  by  White  to  represent  only  part  of  the  Shasta  group  ;  but  later 
observations  by  Diller  and  Stanton  (1893)  show  that  they  correspond  to 
the  whole.  In  Tehama  County  the  total  thickness  is  about  26,000  feet ;  in 
Shasta  County,  where  the  Horsetown  beds  alone  occur,  5200  feet  (Diller, 
Stanley-Brown).  The  Knoxville  or  lower  group  has  among  its  fossils  various 
forms  of  Aucellce  (Figs.  1203-1205,  page  759),  and  the  Horsetown  includes 
in  its  abundant  fauna  many  Ammonites ;  the  species  of  the  two  have  close 
relations  to  the  Neocomian,  Gault,  and  intermediate  beds  of  Europe.  The 
two  groups  in  California  thus  cover  the  whole  of  the  Lower  Cretaceous ;  and 
these  are  continued  in  the  Chico  series  of. the  Upper  Cretaceous  (Diller). 

In  British  America,  the  lower  part  only  of  the  coast  Cretaceous  on  Van- 


MESOZOIC   TIME CRETACEOUS.  819 

couver  and  Queen  Charlotte  Islands  is  referred  to  the  Lower  Cretaceous. 
On  Queen  Charlotte  Islands,  fossil  plants  of  Lower  Cretaceous  species  occur 
in  the  beds,  as  first  discovered  in  1872,  and  reported  in  the  following  year 
by  Dawson.  G.  M.  Dawson  makes  five  subdivisions  of  the  beds  ;  and  the 
three  lower,  C,  D,  E,  9500  feet  thick,  are  now  regarded  as  identical  with  the 
Shasta  group,  on  the  basis  of  several  common  fossils  (Whiteaves,  C.  A. 
White,  T.  W.  Stanton). 

Arctic  Ocean.  —  On  western  Greenland,  in  the  vicinity  of  Disco  Island, 
there,  are  deposits  containing  Cretaceous  and  Tertiary  plants,  and  the  lower 
part  are  the  Koine  group,  of  Heer  (1882),  referred  by  him  to  the  Neocomian 
of  Europe,  and  by  Newberry  and  Fontaine  to  the  age  of  the  Kootanie 
and  Potomac. 

A  portion  of  the  Potomac  formation  in  Maryland  was  referred,  on  account  of  its 
stumps  of  Cycads,  in  1860,  by  P.  T.  Tyson  to  the  "  Wealden"  ;  and  in  1875  to  the  same 
by  W.  B.  Rogers.  A  careful  study  of  the  many  fossil  plants  led  Fontaine  (1889)  to  essen- 
tially the  same  conclusion.  The  remains  of  Reptiles  which  it  has  afforded  (see  beyond) 
are  pronounced  Jurassic  by  Marsh. 

The  Potomac  formation  in  the  region  of  the  Chesapeake  Bay,  in  Maryland,  is  described 
by  N.  H.  Darton  (1893)  as  overlaid  by  beds  of  white  sand,  gravels,  and  brownish  sand- 
stones, which  he  calls  the  Magothy  formation.  It  contains  lignite  and  plant  remains  ;  but 
no  fossils  are  mentioned  for  identifying  or  distinguishing  it ;  and  its  separation  from  the 
Potomac  by  a  plane  of  erosion  is  of  uncertain  importance.  The  Albirupean  group  of 
Uhler  (1888)  consists  chiefly  of  white  sand-beds  occurring  along  the  Chesapeake  Bay, 
and  is  largely  exposed  near  the  head  of  Magothy  River ;  and  it  is  supposed  to  belong  in 
part  with  the  Potomac  formation.  But  such  evidence  is  very  doubtful;  for  the  deposits 
of  sand,  mud,  and  gravel  now  forming  about  Chesapeake  and  Delaware  bays,  and  elsewhere 
along  the  Atlantic  border,  show  that  kinds  of  material,  color,  coarseness,  texture,  struct- 
ure, are  nearly  valueless  characters  for  determining  the  equivalency  of  Cretaceous  and 
later-time  beds  as  well  as  those  of  earlier  time.  All  sorts  are  formed  cotemporaneously, 
and  the  same  sorts  at  successive  epochs. 

On  the  Gulf  border,  the  Tuscaloosa  group  in  Alabama,  as  described  by  Smith  and 
Johnson,  consists  of  clayey  layers  with  intercalated  beds  of  sand ;  it  outcrops  beneath  and 
either  side  of  Tuscaloosa,  along  the  northern  limit  of  the  Cretaceous  belt.  The  thickness 
is  about  1000'.  The  Eutaw  beds  of  Mississippi,  first  described  by  E.  W.  Hilgard,  are 
referred  to  the  group,  as  far  as  non-marine,  by  C.  A.  White.  The  Tuscaloosa  group  is 
described  in  detail  by  E.  A.  Smith  and  L.  C.  Johnson,  in  Bulletin  43,  U.  S.  Greol.  Surv., 
1887,  and  some  observations  are  added  on  the  Eutaw  group  in  Mississippi. 

In  Texas,  the  Lower  Cretaceous  has  a  thickness  to  the  northeastward,  at  Red  River, 
of  1000' ;  to  the  southwestward,  on  the  Rio  Grande,  of  5000' ;  and  northwestward  it  extends 
into  New  Mexico.  At  Kent,  163  miles  east  of  El  Paso,  the  westernmost  station  in  Texas, 
the  thickness  is  made  about  600'  by  Durable  and  Cummins;  550'  of  it  belong  to  the 
Washita  division,  and  are  characterized  by  the  Gryphcea  dilatata  var.  Tucumcari  of  Mar- 
cou,  a  fossil  well  known  from  the  Cretaceous  of  New  Mexico.  In  Kansas,  the  whole 
thickness  is  but  150',  half  of  it  Trinity  sands,  and  the  rest,  the  Fredericksburg  beds 
(Cragin). 

The  more  important  older  investigations  in  Texan  geology  are  those  of  Ferdinand 
Roemer  (1852),  B.  F.  Shumard  (1856-1860),  Marcou  (1854-1859).  Shumard  made  the 
Washita  and  Comanche  Peak  groups  Upper  Cretaceous  ;  and  Marcou  placed  the  upper 
line  of  the  Lower  Cretaceous  between  these 'two  groups,  with  the  Comanche  Peak  lime- 
stone above. 


820  HISTORICAL   GEOLOGY. 

The  Lower  Cretaceous  of  northern  Mexico,  in  Chihuahua  and  Coahuila,  was  described 
by  C.  A.  White  in  1889,  who  speaks  of  the  strata  of  bluish  limestones  as  strongly  upturned 
and  flexed,  and  having  a  thickness  in  the  Sierra  San  Carlos  of  4000'.  Felix  and  Lenk,  in 
their  memoir  of  1890,  1891,  separate  from  the  Cretaceous  of  Texas  a  lower  part,  consisting 
of  gray  to  black  limestones  having  intercalated  clays  as  the  Lower  Cretaceous,  and  refer 
the  rest,  which  consists  chiefly  of  whitish,  somewhat  cherty  limestones,  to  the  Upper.  He 
reports  the  former  as  having  nearly  three  fourths  of  its  46  species  of  described  fossils 
identical  with  the  Neocomian  of  Europe  ;  and  the  latter  as  containing  Radiolite-like  forms, 
with  species  of  Caprina  and  Nerinea. 

The  Kootanie  beds  of  Montana,  which  in  some  places  contain  beds  of  coal  12'  thick, 
were  described  by  Newberry  in  1887,  and  by  H.  Weed  in  1872. 

The  Knoxville  and  Horsetown  beds,  i.e.  the  Shasta  portion  of  the  Shasta- Chico  series, 
have  a  wide  distribution  along  the  Pacific  coast,  extending  with  interruptions  from  south- 
ern California  probably  to  Alaska.  Their  greatest  development,  according  to  Diller,  is 
upon  the  western  border  of  the  Sacramento  valley  of  California,  where  they  are  composed 
chiefly  of  shales  with  only  occasional  sandstones  above  and  many  thin  beds  below.  The 
beds  are  rarely  calcareous,  and  where  the  successively  newer  overlapping  series  come  inr 
lying  unconformably  on  the  pre-Cretaceous  metamorphic  rocks,  local  conglomerates  are 
common.  The  greatest  thickness  of  the  Knoxville  beds  measured  is  nearly  20,000'.  The 
absence  of  faults  is  not  assured.  The  Horsetown  beds  have  a  thickness  of  over  6000',  and 
overlap  the  Knoxville  beds  in  all  directions  toward  the  Cretaceous  shore.  The  conforma- 
bility  of  the  Knoxville  and  Horsetown  beds  and  their  detrital  and  faunal  continuity  in 
both  California  and  Oregon  indicate  uninterrupted  sedimentation  ;  and  the  shoreward 
overlapping  of  the  newer  beds,  with  marked  unconformity  upon  the  pre-Cretaceous  rocks, 
shows  that  upon  the  Pacific  border  the  land  was  subsiding  and  the  sea  encroaching. 


2.  UPPEK  CRETACEOUS. 

Atlantic  Border. 

On  the  Atlantic  border  the  Upper  Cretaceous  formation  outcrops  from 
Martha's  Vineyard,  along  the  islands  south  of  New  England  to  New  Jersey ; 
thence  it  continues  southward,  in  a  narrow  belt  by  the  west  side  of  the 
Tertiary  to  southern  Virginia.  It  occurs  in  North  and  South  Carolina  only 
in  small  patches.  Near  Macon,  G-a.,  a  belt  commences  north  of  the  Tertiary 
area,  which  widens  westward,  and,  on  approaching  the  Mississippi  valley, 
spreads  northward  up  its  east  side  to  the  Ohio  near  Paducah;  where  it 
crosses  the  river  and  narrows  out  in  an  area  of  sandy  clays  and  "  micaceous 
sands  "  like  those  of  the  Kentucky  Cretaceous  beds.  The  rest  of  the  Missis- 
sippi Bay  of  the  Cretaceous  Period  became  covered  later  by  Tertiary  beds  and 
fluvial  deposits. 

The  formation  along  the  New  Jersey  coast  includes  at  bottom  a  fresh- 
water group,  called  the  Raritan,  and,  above  this,  beds  of  greensand  or  marl 
interstratified  with  beds  of  common  sand,  clay,  and  occasionally  of  marine 
shells.  Remains  of  Reptiles  are  sometimes  found  in  the  upper  beds,  and 
occasionally  a  complete  skeleton. 

The  subdivisions  as  laid  down  by  G.  H.  Cook  are  given  in  the  following 
table ;  and  the  epochs  to  which  they  probably  belong  are  also  stated. 


MESOZOIC   TIME  —  CRETACEOUS.  821 

4.   LARAMIE  EPOCH.  — 

Unrepresented  ?  Possibly  here  the  Upper  Ghreensand,  Manasquan 
group  of  W.  B.  Clark :  15  to  20  feet  thick  of  greensand,  with  above, 
sandy  clays  and  blue  marl ;  fossiliferous. 

3.   MONTANA  OB  KIPLEY  EPOCH. — 

2.  Middle  Grreensand,  Eancocas  group  of  Clark :  about  45  feet  of 
marl,  with  as  much  of  yellow  sand  above ;  fossiliferous. 

1.  Lower  Greensand,  Navesink  group  of  Clark:  30  to  45  feet  of 
greensand,  and  above  this  a  red-sand  stratum,  100  feet  thick;  with 
below  Clay  marls,  250  to  300  feet. 

2.   COLORADO  EPOCH. — 

Unrepresented  ?  or  perhaps  the  Clay  marls. 

1.   DAKOTA  EPOCH. — 

Raritan  group  or  Plastic  clays :  thick  beds  of  plastic  clay  with 
some  interstratified  sand-beds;  more  sandy  above;  350  feet;  fossil 
leaves  and  lignite,  especially  toward  the  base  (one  third  of  the  thick- 
ness from  its  base  in  New  Jersey)  ;  shells  rare,  and  these  freshwater 
of  the  genus  Uhio,  or  brackish-water  Gastropods. 

The  Raritan  group  is  proved  by  its  remains  of  plants  to  be  the  probable 
equivalent  of  the  Dakota  of  the  Continental  Interior ;  and  the  Lower  Green- 
sand  group,  by  its  fossils,  as  well  brought  out  by  Whitfield,  to  be  the  equiva- 
lent of  the  Ripley  group  of  the  Gulf  border.  Whitfield  refers  to  the  same  group, 
but  doubtingly,  the  nearly  unfossiliferous  Clay  marls  which  lie  below  it.  The 
Upper  Greensand  group  graduates,  without  a  break  in  the  stratification,  into 
the  overlying  Eocene  Tertiary,  as  if  its  formation  were,  like  the  Upper  Lara- 
mie,  the  closing  work  of  the  Cretaceous  period.  If  not  so,  the  Laramie  epoch 
is  not  represented  on  the  Atlantic  border. 

The  Lower  Greensand  is  the  most  fossiliferous  of  the  series.  Whitfield 
has  described  from  it  19  species  of  Cephalopods,  127  of  Gastropods,  155  of 
Lamellibranchs,  and  2  of  Brachiopods,  or  a  total  of  303  species,  against  47, 
under  the  same  tribes,  from  the  Middle  and  Upper  Greensand  groups.  Not- 
withstanding the  unbroken  passage  of  the  Upper  Greensand  group  into  the 
Eocene  Tertiary,  out  of  the  79  Eocene  species  of  Mollusks  described  by 
Whitfield,  none  occurs  in  the  underlying  Cretaceous. 

The  clay  of  the  Raritan  group  is  partly  pure  white  clay,  but  it  varies  to 
gray,  yellow,  and  red  in  color,  owing  to  traces  of  iron  oxide,  and  in  some 
places  to  black  in  consequence  of  disseminated  fragments  of  lignite  which 
had  been  gathered  from  some  lignitic  bed.  In  general,  it  is  not  laminated 
clay,  like  that  of  nearly  all  river  valleys,  but  a  massive  clay  free  from  lami- 
nation and  of  remarkable  purity.  The  best  of  it  has  great  value  for  the 
manufacture  of  fine  pottery  and  other  purposes. 

The  Raritan  formation,  with  its  massive  clays  of  various  colors,  occurs 


822  HISTORICAL   GEOLOGY. 

also  on  Staten  Island.  It -includes  the  clay-beds  of  northern  Long  Island, 
which  are  well  displayed  at  Glen  Cove,  and  at  various  points  between  this 
place  and  Huntington  and  farther  to  the  eastward ;  and  also  part  of  the 
clays  of  Fisher  Island,  Block  Island,  and  Martha's  Vineyard.  Gay  Head,, 
the  west  cape  of  Martha's  Vineyard,  owes  its  name  to  the  variously  colored 
clay-beds. 

The  several  beds  of  greensand,  or  marl,  consist  of  common  sand  and  black- 
ish to  olive-green  grains  of  glauconite  —  a  silicate  of  iron  and  potash  made 
chemically  within  the  cavities  of  the  shells  of  Rhizopods,  Corals,  and  other 
marine  organic  materials.  The  bluffs  after  a  rain  often  look  black  or  green- 
ish black.  They  are  called  marl-beds  because  the  material  is  useful  as  a 
fertilizer.  The  fertilizing  properties  of  the  marl,  according  to  G.  H.  Cook, 
are  not  due  to  the  potash  of  the  glauconite,  but  to  the  presence  of  some 
lime  phosphate. 

The  fresh-water  origin  of  the  New  Jersey  clay-beds  is  generally  recog- 
nized. The  absence  of  lamination  and  the  thickness  indicate,  not  river  action, 
but  the  existence  of  quiet  fresh-water  areas  parallel  with  the  New  Jersey 
seacoast  and  that  of  southern  New  England  from  New  Jersey  eastward  as 
far  as  Cape  Cod,  or  about  300  miles.  The  coast-line  may  have  been  some 
miles  distant  to  seaward.  Rivers  were  not  the  transporters,  for  they  do  only 
coarser  work.  No  river  in  New  England,  where  f eldspathic  rocks  abound,  is 
now  making  such  non-laminated  clay-beds.  Only  small  streamlets  and  rills, 
could  have  been  concerned ;  and  the  feldspathic  rocks  must  have  been  near 
by.  For  New  Jersey  the  Triassic  granitic  sandstones  may  have  been  the 
feldspathic  rocks  at  hand ;  and  for  Long  Island  and  the  islands  to  the  east- 
ward crystalline  rocks  were  not  far  away  to  the  northward.  The  bleaching 
of  the  deposits  in  the  case  of  the  white  clay-beds  required  the  action  of 
carbonic  acid  or  organic  acids  proceeding  from  the  decomposition  of  beds 
of  peat  or  leaves  underlying  the  Raritan  or  intercalated  with  its  layers; 
for  the  clays  from  granitic  rocks  always  derive  a  tinge  of  iron  oxide  from 
the  black  mica  and  other  iron-bearing  minerals  among  their  constituents. 
The  origin  of  the  clay-beds  in  all  these  particulars  was  very  much  like  that 
of  those  of  the  coal-formation  (page  665). 

After  the  making  of  the  Raritan  beds,  the  sea  regained  access,  as  the 
marine  shells  evince,  to  the  shore  region  of  the  Atlantic  border ;  and  this 
was  the  first  submergence  of  the  border  since  the  close  of  the  Lower 
Silurian.  The  geanticline,  which  was  probably  increasing  through  the 
Paleozoic,  at  last  had  disappeared. 

The  beds  of  greensand  are  supposed  to  have  been  formed  in  moderately 
deep  waters  off  the  coast.  The  least  depth  required  for  the  production  of 
greensand  is  not  known. 

Ehrenberg,  who  first  discovered  that  the  grains  of  glauconite  often  have  the  shape  of 
casts  of  Rhizopod  shells,  also  detected  them  in  the  bones  of  the  Zeuglodon  of  the  Ala- 
bama Tertiary,  which  were  probably  in  shallow  water  when  the  formation  took  place. 
J.  W.  Bailey  reported  in  1856  their  occurrence  in  the  cells  of  recent  Corals  and  Rhizopods, 


MESOZOIC   TIME  —  CRETACEOUS.  823 

over  the  sea  bottom  near  Cape  Hatteras,  at  depths  of  40  or  50  fathoms.  Similar  facts 
were  obtained  abundantly  by  the  ' '  Challenger  "  Expedition,  as  mentioned  by  Murray.  But 
glauconite  grains  have  been  observed  also  as  a  covering  of  stones  and  in  their  clefts,  and 
sometimes  as  the  coloring  material  of  concretions  of  silica  in  the  form  of  opal  (Cayeux). 
The  ingredients  for  maKing  glauconite  must  be  derived  from  the  sea  water  or  sea  bottom, 
or  partly  from  organic  matters  at  hand.  It  has  been  suggested  that  the  silica  may,  in 
some  cases,  have  come  from  minute  sponges  that  had  previously  grown  in  the  cells  which 
it  occupies. 

The  equivalency  of  the  Karitan  clay -beds  of  New  Jersey  and  those  of  Staten  Island 
and  Long  Island  was  announced  in  1843  by  W.  W.  Mather,  on  the  ground  of  their  resem- 
blances. It  was  proved  for  Staten  Island  and  Long  Island  from  the  fossil  leaves,  by  New- 
berry  in  1874,  and  for  Martha's  Vineyard  by  C.  D.  White  in  1890.  Since  the  latter  date 
the  number  of  known  Cretaceous  plants  has  been  increased  by  the  discoveries  of  A.  Hoi- 
lick.  Newberry  pointed  out  the  identity  of  some  of  the  Raritan  plants  with  those  of  the 
Dakota  group. 

Northern  Gulf  Border. 

The  Upper  Cretaceous  beds  of  Alabama  and  Mississippi,  in  the  northern 
Gulf  border  west  of  the  Florida  peninsula,  comprise  the  following  groups :  — 

4.   LARAMIE  EPOCH. — 
Not  represented. 

3.   MONTANA  OR  BJPLEY  EPOCH.  — 

Ripley  group:  hard  white  limestone  200  to  300  feet  thick,  often 
sandy,  with  but  little  green  sand  or  glauconite  in  the  beds. 
Also  the  upper  part  of  the  Rotten  limestone. 

2.   COLORADO  EPOCH  ?  — 

Lower  part  of  Rotten  limestone:  hard  or  soft  chalky  limestone; 
total  thickness  of  Eotten  limestone  500  to  1200  feet. 

1.   DAKOTA  EPOCH  ? ;  possibly  Lower  Colorado.  — 

Upper  Eutaw  beds  of  Alabama ;   Tombigbee  sands  of  Mississippi. 

The  limestones  on  the  Gulf  border  diminish  in  thickness  to  the  eastward 
and  fail  wholly  in  Georgia,  where,  according  to  J.  W.  Spencer,  the  Florida 
axis  probably  determined  the  eastern  limit  of  the  Cretaceous  belt.  The  beds 
in  that  state  consist  of  mixed  clays  and  sands,  and  are  about  1385  feet  thick, 
with  few  fossils.  They  look,  according  to  Spencer,  as  if -made  from  sedi- 
ments of  fluvial  origin. 

The  Kipley  group,  as  brought  out  in  Whitfield's  paleontological  report,  is; 
the  equivalent  of  the  Lower  Greensand  group  of  the  New  Jersey  Cretaceous,, 
and  of  its  continuation  through  Delaware,  Maryland,  and  North  Carolina. 
In  view  of  the  much  better  preservation  of  the  fossils  on  the  Gulf  border, 
Stanton  speaks  of  the  Ripley  fauna  as  having  this  wide  range.  The  number 
of  identical  species  along  the  Atlantic  and  Gulf  borders  is  large,  as  shown  in 
the  lists  of  species  given  beyond. 


824  HISTORICAL   GEOLOGY. 

In  Tennessee  and  Kentucky,  the  Ripley  group  is  represented  chiefly  by  micaceous  clays 
and  sand-beds ;  and,  while  the  thickness  is  400'  to  500'  in  Tennessee,  it  becomes  a  few 
scores  of  feet  in  Kentucky. 

Below  it,  in  southern  Tennessee,  lie  200'  to  300'  of  beds,  sparingly  calcareous,  repre- 
senting the  Rotten  limestone,  and  at  bottom,  the  "  Coffee  sands  of  Safford,  200'  thick"  ; 
which  are  Lower  Cretaceous.  The  age  of  the  beds  below  the  Ripley  group  on  the  Gulf 
border,  as  Stanton  remarks,  is  not  clearly  defined  by  the  fossils,  and  the  Colorado  epoch 
is  therefore  not  known  positively  to  be  represented.  The  Rotten  limestone  contains  many 
Ripley  fossils.  During  the  Laramie  epoch,  according  to  White  and  Stanton,  the  Atlantic 
and  Gulf  borders  were  probably  somewhat  emerged,  the  Ripley  beds  being  covered  directly 
by  beds  with  Eocene  fossils. 

Western  Gulf  Border. 

In  Texas,  the  Upper  Cretaceous  beds  are  2000  feet  thick  (E.  T.  Hill). 
There  are  sand-beds  and  clays  at  base  which  are  non-marine ;  and  above  these 
thick  beds  of  limestone  with  much  chalk,  followed  by  marls  and  greensand. 
They  extend  northeastward  into  Arkansas,  and  westward  through  the  Trans- 
Pecos  region  and  its  mountains,  to  northeastern  Mexico,  where  they  occur 
in  the  states  of  Chihuahua,  Coahuila,  and  Tamaulipas,  chiefly  along  the 
mountain  region  between  Presidio  del  Norte  and  Tainpico,  resting  on  the 
Lower  Cretaceous  conformably,  although  upturned. 

The  subdivisions,  as  determined  by  Hill,  are  as  follows :  — 

4.   LARAMIE  EPOCH. — 

Laramie  series  in  western  Texas. 
3.   MONTANA  EPOCH.  — 

Exogyra  ponderosa  marls,  with  glauconitic  (or  greensand)  beds 
(Navarro  beds,  Eagle  Pass  beds)  above :  chalk,  overlaid  by  marls 
and  greensand. 

2.   COLORADO  EPOCH. — 

2.  Austin  limestone,  or  Austin-Dallas  chalk ;  300  to  500  feet  thick. 
1.  Eagle  Ford  shales;  500  feet  thick. 

1.   DAKOTA  EPOCH.  — 

Lower  Cross  Timber  sands;  300  feet  thick. 

The  beds  are  marine,  excepting  the  sand  and  clays  of  the  Lower  Cross 
Timber  sands,  and  some  beds  of  the  Eagle  Ford  shales.  The  fossils  are  all 
different  from  those  of  the  Lower  Cretaceous  beds.  The  Glauconite  group 
contains  over  40  species  of  fossils,  identical,  according  to  Stanton,  with  those 
of  the  Eipley  fauna,  and  many  also  of  the  species  of  the  Montana  group  in 
the  Continental  Interior. 

Continental  Interior. 

The  Cretaceous  beds  of  the  Interior  Continental  Sea  were  early  studied 
by  Meek  and  Hayden,  and  their  subdivisions  in  the  main  are  those  still 
in  use. 


MESOZOIC   TIME  —  CRETACEOUS.  825 

4.   LARAMIE  EPOCH.  — 

2.  Upper  Laramie  or  Denver  group:  fresh-water  beds  of  sand- 
stone, conglomerates ;  and  partly  of  eruptive  material  (andesytic, 
etc.)  ;  with  or  without  coal-beds. 

1.  Lower  Laramie :  fresh-water  beds  of  coarse,  friable  sandstones, 
often  cross-bedded,  with  clay-beds ;  occasional  fossiliferous  brackish- 
water  beds ;  with  beds  of  bituminous  coal,  in  some  places  "  15  to  20 
coal-beds  in  1000  feet ; "  thickness  1000-5000  feet. 

3.   MONTANA  EPOCH.  — 

2.  Fox  Hills  group:   sandstones  and  shales  with  many  marine 
fossils ;  maximum  thickness,  1000  feet. 

1.  Fort  Pierre  group :  plastic  clays,  sand-beds  often  with  limestone 
concretions ;  marine  fossils ;  maximum  thickness  7700  feet. 

:2.   COLORADO  EPOCH. — 

2.  Niobrara  group:   calcareous   marls,   chalk,   shales,   sandstones, 
with  limestones  ;  marine  fossils  ;  maximum  thickness  2000  feet. 

1.  Fort  Benton  group  (near  Fort  Ben  ton) :  laminated  clays,  lime- 
stone, with  marine  fossils  ;  maximum  thickness,  1000  feet. 

Probably  includes  the  Coalville  coal-bed,  with  1500  feet  of  the 
lower  part  of  the  Coalville  group. 

1.   DAKOTA  EPOCH. — 

Dakota  group:  sandstones,  clays,  some  lignitic  layers,  with  con- 
glomerates sometimes  at  base;  fossil  leaves  abundant,  and  other 
evidences  of  fresh-water  origin,  and  little  of  brackish  or  marine 
waters.  Probably  includes  the  Bear  River  coal-beds. 

The  grouping  of  the  subdivisions  adopted  above  (which  accords  with  the 
results  of  Meek's  paleontological  work)  and  the  terms  used  are  those  of 
G.  H.  Eldridge.  The  name,  Lignitic,  used  by  Meek  and  Hayden  for  the 
Upper  division  (which  they  made  Lower  Tertiary),  was  changed  by  King 
in  1878  to  Laramie.  Subdivisions  of  the  Laramie  into  Lower  and  Upper  is 
based  chiefly  on  the  work  of  Cross  (1888  and  later). 

The  Cretaceous  was  the  coal  period  of  western  America.  As  Paleozoic 
time,  the  era  of  extended  continental  submergence,  closed  with  the  slow 
emergence  of  the  eastern  half  of  the  continent,  so  Mesozoic  time,  the  era  of 
extensive  submergence  of  the  western  half  of  the  continent,  closed  with  the 
slow  emergence  of  this  western  half.  And  the  later  coal-beds,  like  the  earlier, 
mark  long  periods  of  small  emergence  and  persistent  marshes  in  the  alter- 
nating conditions  of  level.  The  Upper  Cretaceous  affords  coal  at  different 
levels  :  at  Bear  River,  western  Wyoming,  and  at  Mill  Creek,  British  America, 
in  the  Dakota  group ;  at  Coalville,  Utah,  in  the  Colorado  group  (Stanton) ; 
and  at  Dunvegan,  Peace  River  region  (117-J0  W.,  56°  N.)  (Dawson)  ;  in  the 
Belly  River  region,  north  of  Montana,  on  Vancouver  Island,  at  Nanaimo  and 


826  HISTORICAL   GEOLOGY. 

Comox,  and  in  the  Bow  Eiver  region,  north  of  Montana,  probably  in  beds  of 
Montana  age  (Dawson). 

But  the  coal-beds  are  mostly  in  the  Laramie  formation.  They  are  worked 
for  coal  in  Colorado,  Utah,  Wyoming,  Montana,  and  New  Mexico.  In  Colo- 
rado alone  the  coal-fields  have  an  aggregate  area  of  about  18,000  square  miles 
(R.  C.  Hills,  1892).  The  beds  are  often  five  to  six  feet  in  thickness,  and 
one  at  Evanston,  in  western  Wyoming,  has  been  described  as  26  feet  thick. 
In  British  America,  at  Edmonton  (1131°  W.  53^°  K),  and  in  the  Souris  dis- 
trict, there  are  Laramie  coal-beds. 

In  Gunnison  County,  Col.,  at  Crested  Butte,  a  bed  of  anthracite  five  feet 
thick  is  worked ;  and  in  New  Mexico,  at  the  Old  Placer  Mountain,  eight  miles 
east  of  San  Antonio,  is  another  locality  of  anthracite.  The  anthracite  is  a. 
result  of  alteration  by  the  heat  of  eruptive  rocks. 

To  appreciate  the  position  and  width  of  the  Cretaceous  seas  over  the- 
western  Continental  Interior  during  the  Colorado  and  Montana  epochs,  and 
especially  the  Niobrara  portion  of  the  former,  the  reader  should  refer  again 
to  the  map  on  page  813 ;  and,  still  better,  to  some  colored  geological  map  of 
North  America. 

Their  eastern  border  extended,  from  what  is  now  western  Texas,  east- 
ward and  northward  over  central  Kansas,  and  thence  along  eastern 
Nebraska  and  Dakota  into  British  America.  In  the  western  portion  of 
these  interior  waters  there  were  the  large  Archaean  islands  of  the  protaxis, 
high  lands  and  low  lands  varying  in  limits  with  oscillations  in  level,  which 
were  mostly  forest-clad,  and  well  populated,  as  evidence  shows,  by  Mammals, 
Amphibians,  and  Reptiles,  the  Reptiles  taking  the  lead  in  size  and  power. 
Beyond  these  islands  the  seas  spread  still  westward  over  nearly  all  of 
Wyoming  arid  Utah  to  a  line  passing  southward  through  Great  Salt  Lake, 
where  the  western  shores  lay  along  the  lands  of  the  Great  Basin. 

In  the  progress  of  the  Upper  Cretaceous,  the  non-marine  Dakota  epoch 
was  followed  by  a  second,  the  COLORADO,  in  which  the  Interior  sea  gradually 
attained  ocean-like  conditions,  and  was  inhabited  by  great  Mosasaurids  or 
Pythonomorphs,  and  Sea-Saurians  related  to  the  Plesiosaurs,  as  well  as 
Sharks  and  Saurodont  Fishes.  Even  before  the  Niobrara  beds  had  all  been 
deposited,  a  shallowing  had  begun  in  Kansas.  S.  W.  Williston  states  that 
in  the  beds  of  Kansas  Invertebrates  abound;  that  Reptilian  remains  are 
unknown  in  the  lower  part  of  the  Niobrara  beds  within  100  feet  of  the  base, 
but  higher  up  are  common  fossils.  "  Species  of  two  or  three  genera  of 
Mosasaurs  occur  at  different  levels,  but  those  of  Clidastes  [Edestosaurus 
of  Marsh]  only  in  the  upper  part.  Turtles  are  rare  in  the  lower  portion, 
while  very  common  in  the  uppermost  beds." 

This  shallowing  was  general  over  the  Continental  Interior  as  the  Colorado 
epoch  closed.  Moreover,  the  Colorado  fauna,  in  some  unexplained  way, 
disappeared.  During  the  Montana  epoch  the  waters,  however,  were  still 
salt,  and  marine  life  was  abundant,  and  included  Plesiosaurids.  But  the 
shallowing  was  continued ;  and  in  the  following  Laramie  epoch  the  waters 


MESOZOIC   TIME  —  CRETACEOUS.  827 

were,  to  a  large  extent,  fresh,  and  only  occasionally,  or  else  locally,  brackish. 
Moreover,  at  many  intervals,  great  areas  emerged  which  were  speedily 
covered  with  marshes  and  forests  in  the  warm  and  moist  climate,  and  thus 
peat-beds  were  made,  which  later  became  coal-beds. 

The  length  of  the  Laramie  Interior  Sea  in  this  condition  was  nearly  2000 
miles,  it  reaching  to  the  parallel  of  57°  N. ;  and  another,  the  Mackenzie  valley 
area,  opening  on  the  Arctic  Ocean,  was  500  miles  long.  The  southern  of 
these  Laramie  areas  was  probably  tidal  as  well  as  the  northern.  For  the 
width  south  of  49°  K.  was  600  to  800  miles,  —  which  is  too  great  for  fluvial 
waters.  Besides,  the  strata  are  generally  cross-bedded  in  stratification,  and 
they  include  occasionally  conglomerates,  proving  seemingly  strong  move- 
ments in  opposite  directions,  and  at  times  in  some  parts  violent  currents. 
Moreover,  although  the  waters  were  generally  fresh,  still  Sea-Saurians,  Sharks, 
and  other  marine  species  occasionally  ascended  to  Dakota  and  beyond. 
The  bay  received  the  drainage  from  all  the  bordering  lands  for  the  2000 
miles  from  the  Mexican  Gulf  to  the  limit  of  the  Laramie  beds  in  British 
America ;  and  hence  a  great  amount  of  fresh  water  flowed  southward  toward 
the  outlet. 

Hence  the  tides  from  the  western  part  of  the  gulf  generally  carried 
in  salt  waters  for  a  short  distance  only,  and  thence  the  tidal  movement 
was  propagated  northward  by  the  fresh  waters.  But  occasionally  the 
Gulf  waters  were  able,  through  a  subsiding  in  the  land,  to  flow  far  north- 
ward, and  let  in  the  Sea-Saurians,  and  Sharks,  the  Oysters,  and  other  Sea- 
Mollusks,  so  as  to  make  the  brackish-water  fossiliferous  beds  of  the  Laramie 
formation.  The  spawn  of  Oysters  and  other  Mollusks  would  have  been 
rapidly  transported. 

If  the  above  explanation  of  the  conditions  in  the  Laramie  epoch  is 
correct,  the  distance  to  which  the  salt  waters  of  the  Gulf  were  carried  in 
westward  and  northward,  whether  one  mile  or  many,  is  a  subject  for  investi- 
gation. The  Laramie  beds  derived  their  material  from  the  land  on  the 
borders  of  the  Interior  Sea.  The  existence  of  Paleozoic  and  Mesozoic  rocks 
of  various  ages  about  the  base  of  the  Black  Hills,  where  there  is  also  the 
Cretaceous  formation,  indicate  how  the  other  adjoining  Archaean  lands  may 
have  been  skirted,  where  now  covered  by  Tertiary  beds  and  those  of  the 
later  Cretaceous. 

The  Upper  Laramie  or  Denver  group  was  first  defined  by  Cross  and 
Eldridge  in  1888.  It  derives  the  latter  name  from  its  distribution  about 
the  city  of  Denver,  east  of  the  Front  Range  (Archaean)  of  the  Rocky  Moun- 
tains, where  it  overlies  the  Lower  Laramie.  It  is  described  as  resting  on 
the  latter  unconformably,  —  the  unconformity  being,  however,  not  that  of 
bedding  in  a  marked  degree,  but  the  unconformity  consequent  on  the  previous 
erosion  of  the  beds  on  which  the  formation  was  deposited.  The  upper  por- 
tion in  that  region,  1400  feet  thick,  consists  largely  of  the  debris  of  eruptive 
rocks,  mostly  different  kinds  of  andesytes ;  while  the  lower  part,  800  feet 
thick,  distinguished  as  the  Arapahoe  beds,  is  mostly  made  up  of  conglom- 


828  HISTORICAL   GEOLOGY. 

erates  formed  out  of  various  older  stratified  rocks,  some  identified  as  Car- 
boniferous by  their  fossils.  The  occurrence  of  eruptive  debris  in  the  Laramie 
beds  of  other  regions  has  been  regarded  as  a  probable  sign  of  Denver  age. 
The  plants  include  species  not  found  for  the  most  part  in  the  Lower 
Laramie.  The  Denver  group  has  afforded  Horned  Dinosaurs  (Ceratopsids) 
and  other  kinds,  showing  their  Mesozoic  relations.  Ordinary  Mammals  are 
absent,  and  all  other  evidence  of  a  Tertiary  fauna. 

To  the  Upper  Laramie  are  referred,  by  Cross,  —  on  the  ground  of  the 
plants  (studied  by  Knowlton)  as  well  as  the  eruptive  conglomerates  and 
unconformity  at  base  chiefly  by  erosion,  —  beds  in  the  Middle  Park,  and  at 
other  localities,  from  Greeley,  Col.,  to  the  Katon  Mountains  in  New 
Mexico ;  and  beds  about  Livingston,  in  Central  Montana,  called  by  W.  H. 
Weed  the  Livingston  beds  ( U.  8.  G.  8.  Bulletin,  No.  105,  1893).  The  latter, 
as  described,  have  a  thickness  of  7000  feet,  and  rest  over  1000  feet  of  Laramie 
beds,  but  were  deposited,  like  the  Denver,  after  a  time  of  extensive  erosion, 
and  therefore  the  conformability  is  not  perfect.  The  group,  however, 
according  to  Weed,  has  a  brackish-water,  oyster-bearing  layer,  which  is  well 
packed  with  oyster  shells,  Laramie-like,  at  a  height  of  200  feet  above  its 
base,  that  is,  above  the  plane  of  extensive  erosion. 

In  southern  Wyoming,  along  Bitter  Creek,  in  the  vicinity  of  the  Union 
Pacific  Railway,  near  Hallville,  Black  Butte,  Point  of  Rocks,  Rock  Spring, 
and  elsewhere,  the  Laramie  contains  a  number  of  coal-beds.  South  of  Black 
Butte  there  are  nine  or  more  distinct  coal-beds ;  and  between  two  of  them 
were  obtained  remains  of  a  Horned  Dinosaur  (Agathaumas  of  Cope). 

Beds  in  eastern  Wyoming,  called  by  Marsh  the  "Ceratops  beds,"  are 
referred,  with  a  query,  by  Cross  to  the  Upper  Laramie,  because  of  the 
presence  of  Ceratopsids  in  both ;  but  to  the  Lower,  by  Marsh.  They  rest  on 
400  feet  of  sandstone  conformably,  and  the  sandstone  directly  on  Fox  Hills 
beds,  and  contain  no  eruptive  debris.  Besides  Horned  Dinosaurs  of  several 
species,  the  beds  have  afforded  remains  of  other  Dinosaurs  related  to  the 
Iguanodon  and  Megalosaurs,  and  of  Marsupial  and  Oviparous  Mammals. 
Above  the  stratum  containing  the  fossils  there  is  a  bed  of  coal,  the  Shawnee 
coal-bed,  10  inches  thick. 

" Judith  River"  beds  in  northern  Montana,  first  described  by  Hayden 
and  Meek,  afford  Dinosaurs  of  the  same  genera,  according  to  Marsh,  as  the 
Ceratops  beds,  besides  many  others,  including  Plesiosaurids  ;  and  also  re- 
mains of  Sharks,  Chimseroids,  Ganoids,  and,  as  other  evidence  of  brackish- 
water  conditions,  shells  of  Ostrea,  Anomia,  Corbicula,  Corbula,  and  Goniob- 
asis. 

The  Fort  Union  beds,  near  the  border  of  North  Dakota  and  Montana,  have 
been  referred  to  the  Upper  Laramie  and  also  to  the  Tertiary.  They  are  of 
doubtful  relations. 

The  most  eastern  "  Lignitic "  beds  referred  to  the  Laramie  are  those  of 
South  Dakota,  near  Moreau  River,  west  of  the  Missouri,  in  101°  W.,  where 
remains  of  two  Plesiosaurids  have  been  found,  Plesiosaurus  occiduus,  and 


MESOZOIC    TIME CRETACEOUS.  829' 

Ischyrosaurus  antiquus,  both  described  by  Leidy  in  1873.     Nothing  of  the 
Laramie  is  recognized  in  Kansas. 

The  Reptiles  and  other  fossils  in  the  beds  referred  to  as  Upper  Laramie 
indicate  not  only  their  Cretaceous  age,  but  also  their  close  relations  to  the 
Lower  Laramie.  At  present  the  line  between  the  two  divisions  cannot  be 
definitely  drawn. 

The  subdivisions  of  the  Rocky  Mountain  Cretaceous,  including  the  Laramie,  were  first 
described  by  Hayden  and  Meek.  Their  papers  commenced  in  1856,  and  appeared  at  inter- 
vals for  20  years.  Meek's  Report  on  the  fossils,  in  which  the  stratification  is  reviewed, 
constitutes  vol.  ix.  of  the  Reports  of  the  Hayden  Expedition  (1876).  Their  subdivisions 
were  the  Dakota,  Fort  Benton,  Niobrara,  Fort  Pierre,  and  Fox  Hills.  The  Tertiary  sec- 
tion in  the  "Upper  Missouri  region,"  described  by  Meek  and  Hayden,  contained: 
(1)  Dakota  group,  400' ;  (2)  Fort  Benton,  800' ;  (3)  Niobrara,  200' ;  (4)  Fort  Pierre,  700' ;. 
and  (5)  Fox  Hills,  500'.  G.  H.  Eldridge  in  1889  grouped  the  divisions  into  the  three : 

(1)  Dakota ;  (2)  Colorado,  and  (3)  Montana.     C.  A.  White  had  earlier  recognized  (1876) 
the  same  grouping  under  the  names  Dakota,  Colorado,  and  Fox  Hills. 

The  Colorado  formation  and  its  relations  to  the  other  divisions  of  the  Cretaceous  have 
been  reviewed  in  detail  by  T.  W.  Stanton  ;  and  from  his  report  of  1893  many  of  the  follow- 
ing facts  are  taken.  The  thickness  of  the  Upper  Cretaceous  series  at  the  Black  Hills  is 
less  than  1000' :  (1)  the  Dakota,  250'-400' ;  (2)  the  Colorado,  300'-500' ;  (3)  the  Montana, 
150'-350'  (H.  Newton).  In  Cinnabar  Mountain,  Montana,  the  total  thickness,  according 
to  Weed,  is  about  4300' :  (1)  the  Dakota,  526'  ;  (2,  3)  the  Colorado  and  Montana,  2850' ; 
(4)  the  Laramie,  935'.  East  of  the  Front  Range,  in  Colorado,  the  Dakota  outcrops  at  the 
base  of  the  range,  and,  outside  of  this,  the  other  later  groups  in  succession,  as  first  shown i 
by  Marvine.  In  the  Denver  region  there  are  :  (1)  Dakota,  300' ;  (2)  Colorado,  1100',  of 
which  400  is  Fort  Benton  and  700  Niobrara  ;  (3)  Montana,  8700',  of  which  the  Fort  Pierre, 
7700',  and  Fox  Hills,  800'-1000'~;  (4)  the  Laramie  with  the  Denver  group,  2000'.  The 
thickness  diminishes  southward,  and  between  Canon  City  and  Pueblo,  on  the  Arkansas 
River,  the  Montana  group  is  but  3000'  thick.  The  section  at  Coalville,  in  Utah,  according 
to  Stanton,  which  is  peculiar  in  containing  a  great  coal-bed  in  the  Colorado  portion,  con- 
sists as  follows:  (1)  Dakota,  5000'?;  (2)  Colorado,  1560'-1660',  mostly  sandstone  and 
fossiliferous,  but  with  a  heavy  bed  of  coal  at  the  top  of  the  lower  stratum  of  500'  to  600' ; 
(3)  Montana,  about  2900',  of  sandstone  and  shales,  with  probably  1500'  of  beds  above; 
and  in  the  part  referred  to  the  Montana  group  on  account  of  the  marine  fossils,  there  are 
some  thin  plant  beds,  the  fossil  plants  of  which  are  in  part  Laramie. 

The  Kansas  Cretaceous  consists,  according*  to  S.  W.  Williston,  of  350'  to  400'  of 
Dakota  beds,  300'  to  400'  of  overlying  shales  and  limestone  of  the  Benton  group,  and  400' 
to  450'  of  chalk  and  other  beds  of  the  Niobrara,  making  the  Colorado  series  700;  to  850' 
in  thickness;  and  above  these,  50'  to  100r  of  beds  of  the  Montana  group.  The  Laramie 
is  absent,  the  next  beds  above  being  those  of  the  Loup  Fork  Miocene  Tertiary. 

Newberry  divided  the  Cretaceous  of  New  Mexico  into:   (1)  Dakota,  250'  to  400'; 

(2)  Colorado,  1200'  to  1500' ;  and  (3)  Montana,  1500',  part  of  the  Laramie  being  here 
probably  included.     (Macomb's  Expl.Exp.,  with  a  review  by  Newberry  of  the  conclusions 
he  presented  in  Lieutenant  Ives's  Rep.  on  the  Colorado  River  of  the  West.) 

The  age  of  the  Laramie  beds  (or  the  Lignitic,  as  they  were  called),  whether  Tertiary 
or  Cretaceous,  was  left  undecided  by  Meek  in  his  report  of  1870.  To  the  Lignitic  horizon 
he  referred  the  Judith  fiiver  group,  occurring  at  the  mouth  of  Judith  River  in  Montana, 
having  there  a  thickness  of  about  415'  and  consisting,  beginning  below,  of  sands  and  clays 
with  Unio,  100' ;  impure  lignite,  25' ;  sand  and  clay-beds  with  shells  and  Dinosaurian 
remains,  100' ;  sand  and  clay,  100' ;  impure  lignite  with  Ostrea,  10' ;  sandy  marl  with  some 
lignite  and  species  of  Ostrea,  Corbicula  (3  species),  Goniobasis,  salt-water  species,  80'. 


830  HISTORICAL   GEOLOGY. 

The  Fort  Union  group  (first  examined  by  Hayden  in  1860)  also  was  placed  in  this 
connection  by  Meek,  on  the  ground  of  its  fresh-water  shells  and  lignite.  The  group  was 
estimated  by  Hayden  to  have  a  thickness  of  2000'.  He  reported  it  (1871)  as  extending 
southward  from  Fort  Union,  across  the  Yellowstone  between  the  Black  Hills  and  Big  Horn 
Mountains,  and  northward  into  British  America  ;  but  the  conclusions  were  not  based  on 
a  full  study  of  the  region.  The  150  feet  of  deposits  exposed  near  Fort  Union  include  three 
beds  of  impure  "lignite,"  1',  1-5',  and  4  inches  thick,  alternating  with  beds  of  indurated 
clay  and  clayey  sands,  20'  to  70'  thick  containing  occasionally  land  shells  and  some  leaves. 
The  age  of  the  Fort  Union  beds  has  remained  doubtful.  Newberry  (1890)  separated  it 
from  the  Laramie  on  the  ground  of  differences  in  the  plants ;  L.  F.  Ward  refers  it  on  the 
same  ground  to  the  Upper  Laramie. 

The  beds  in  Middle  Park,  Col.,  referred  to  the  Denver  horizon  by  Cross,  consist 
largely  of  andesytic  breccia,  sand-beds  and  conglomerates,  and  are  800'-900'  in  thickness 
(Marvine).  They  rest  on  upturned  Cretaceous  strata. 

Underneath  the  Fort  Pierre  group  in  the  Belly  River  district,  Canada,  fresh-water 
beds  occur  containing  fossil  leaves,  which  have  been  called  the  Belly  River  group.  The 
plants  are  in  part  identical  with  the  Laramie  (Dawson,  1886).  The  Dunvegan  beds,  on 
Peace  River,  are  supposed  to  be  of  the  same  age.  A  large  area  has  been  referred  to  the 
Laramie  in  British  America  extending  from  the  United  States  boundary  to  the  55th  paral- 
lel, and  eastward  to  111°  W.  ;  in  it  have  been  recognized  a  Lower  Laramie  or  St.  Mary 
River  series  ;  a  Middle,  the  Willow  Creek  beds  ;  an  Upper,  or  Porcupine  Hills  beds,  which 
correspond  in  fossils  to  the  Souris  River  beds,  just  north  of  the  United  States  boundary. 
A  more  eastern  area  extends  from  49°  N.  to  51°  N.,  between  102°  and  109°  W. 

In  Manitoba,  Central  North  America,  the  Cretaceous  formation  is  nearly  2000'  thick ; 
and  the  Montana  group  contains  in  its  lower  part  many  Rhizopod  shells  with  some  Radio- 
larians.  The  thickness  of  the  Dakota  beds  in  this  region  is  13'  to  200' ;  of  the  Colorado 
beds,  200'  to  700' ;  and  of  the  Montana,  over  1000'.  The  Cretaceous  rests  unconformably 
on  the  Devonian  (J.  B.  Tyrrell,  1892).  Fossil  plants  from  Laramie  beds  in  the  Mackenzie 
River  have  been  described  by  Dawson  (1882  to  1889)  and  identified  with  others  from 
Alaska. 

Pacific  Border. 

On  the  Pacific  Border,  the  Upper  Cretaceous,  or  the  Chico  beds,  occupies 
a  broad  belt  extending  originally  from  Lower  California  northward  beyond 
the  Queen  Charlotte  Islands.  It  formerly  covered  the  region  of  the  Coast 
and  Cascade  ranges,  reaching  the  western  base  of  the  Sierra  Nevada  in  Cali- 
fornia, and  of  the  Blue  Mountains  in  Oregon.  Its  eastern  limit  is  indicated 
upon  the  map  on  page  813. 

The  Upper  Cretaceous  of  California  includes  only  the  Chico  beds  of  the  Shasta-Chico 
series.  The  Tejon,  which  Gabb  considered  Cretaceous,  has  been  shown  by  Conrad, 
Heilprin,  and  White  to  be  Eocene.  The  Wallala  beds  of  White  and  Becker  (1885), 
according  to  Dall  and  Fairbanks  (1893),  are  only  a  phase  of  the  Chico.  The  Chico  beds 
are  exposed  upon  both  sides  of  the  Sacramento  valley.  Thence  they  extend  southward 
near  the  cOast  to  Lower  California,  according  to  Lindgren  and  Fairbanks,  and  northward, 
with  local  interruptions,  to  Jacksonville,  and  Riddles,  Oregon ;  and  beneath  the  covering 
of  later  lavas  they  are  supposed  to  connect  with  the  Chico  of  eastern  Oregon  (Diller).  The 
lower  portion  of  the  Chico  beds  consists  chiefly  of  sandstone  and  conglomerate,  and  ranges 
from  900'  to  1400'  in  thickness.  In  the  upper  portion  shale  predominates,  excepting  near 
the  shore  line  where  the  sediments  are  generally  coarse.  The  greatest  thickness  of  the  Chico, 
according  to  Diller,  is  nearly  4000'  in  Tehama  County,  Cal.;  it  thins  out  northward  and 


MESOZOIC   TIME  —  CRETACEOUS.  831 

-eastward,  overlapping  toward  the  Cretaceous  shore,  beyond  the  Knoxville  and  Horsetown 
beds,  which  form  the  lower  part  of  the  Shasta-Chico  series.  The  Chico  thus  comes  in  un- 
conformable  contact  with  the  Jura-Trias  and  Carboniferous  and  extends  inland  from  the 
Lower  Cretaceous,  as  indicated  upon  the  map,  to  the  dotted  line.  The  subsidence  and 
•consequent  transgression  of  the  sea  that  gave  rise  to  the  landward  overlapping  of  the 
later  beds  of  the  Shasta-Chico  series  began  soon  after  the  great  upheaval  at  the  close  of  the 
Jurassic,  and  continued  to  at  least  the  middle  of  the  Upper  Cretaceous  (Diller). 

In  the  Tertiary  the  Tejon  beds  of  California  are  conformable  with  the  Chico,  and  they 
were  regarded  by  Gabb,  and  also  by  White,  as  faunally  continuous.  The  Tejon  is  absent 
in  northern  California,  and  in  Oregon  it  rests  unconformably  upon  the  Shasta-Chico  series. 
(Diller,  1893.) 

In  Washington,  the  Puget  group  of  White,  underlying  the  Tejon,  is  a  non-marine 
formation  containing  beds  of  coal.  It  extends  from  near  the  Columbia  to  the  Puget  Sound 
region,  and  is  several  thousand  feet  hi  thickness.  From  its  Molluscan  and  Plant  remains 
it  has  been  supposed  by  Newberry  and  White  to  represent  a  part  of  the  Laramie  or  Tejon 
group.  Baculites  Chicoensis  shows  the  presence  of  Chico  beds  on  the  Snoqualmie  and 
other  rivers  at  the  western  foot  of  the  Cascade  Range.  The  same  beds  are  found  at  Lucia 
Island,  just  north  of  Puget  Sound,  and  connect  with  the  coal-bearing  Nanaimo  beds  of 
Dawson  upon  the  eastern  side  of  Vancouver  Island.  Their  correlation  with  the  Chico  of 
California  is  well  established  by  fossils.  (Diller.) 

In  Vancouver  and  Queen  Charlotte  Islands,  over  the  Lower  Cretaceous,  there  are 
(1)  the  Middle  Cretaceous,  consisting  of  sandstones,  shales,  and  conglomerates  (which  are 
9700'  thick  in  the  latter),  and  (2)  Upper,  consisting  of  shales  and  sandstones  (1500'  thick 
in  the  latter).  G.  M.  Dawson  (1886). 

In  Greenland,  the  plant  beds  of  the  vicinity  of  Disco  Island,  described  by  Heer,  above 
the  FromS  group,  or  Lower  Cretaceous,  consist  of  (1)  the  Atane  group  of  the  Middle 
Cretaceous,  corresponding  nearly  to  the  Colorado  group,  and  (2)  the  Patoot  group  of  the 
Upper,  corresponding  nearly  to  the  Montana  group. 

LIFE. 

1.  LOWER  CRETACEOUS. 

PLANTS.  —  The  beds  have  afforded  the  earliest  remains  of  the  modern 
groupT  of  Angiosperms.  They  are  associated  with  many  species  of  Cycads, 
and  the  flora  has  therefore  a  transitional  character  between  that  of  the  Jurassic 
and  the  Upper  Cretaceous.  Eemains  of  more  than  300  species  have  been 
described  by  Fontaine  from  the  Potomac  formation  (  U.  S.  G.  S.,  4to,  1889). 
Among  them  are  75  Angiosperms,  22  Cycads,  over  90  Conifers,  and  140 
Ferns.  In  1894,  30  Cycad  trunks  were  found  in  Maryland. 

Some  of  them  occur  in  the  Wealden  (or  Neocomian)  of  England,  as 
Pecopteris  Browniana,  Aspidium  Dunkeri,  Sphenopteris  Mantelli  (Fig.  1353), 
and  two  Conifers  of  the  genus  Splienolepidium.  Four  of  the  nine  species  of 
Sequoia  or  Redwood  (the  genus  to  which  the  giant  trees  of  California  belong) 
agree  with  species  described  by  Heer  from  the  older  Greenland  Cretaceous. 
The  Cycad  trunks  of  Maryland  are  of  the  species  Cycadeoidea  Marylandica 
(Tysonia  M.  of  Fontaine).  No  species  is  identical  with  any  of  those  from 
Triassic  beds.  The  Angiosperms  include  species  of  Ficus  (Fig.  1351)  or 
Ficophyllum,  Sassafras,  Aralia,  Myrica,  Platanus  (or  Plane  tree),  etc. ;  and 
several  of  the  genera,  as  those  of  Ficophyllum,  Protceiphyllum,  have  compre- 


832 


HISTORICAL    GEOLOGY. 


hensive  features,  indicative  of  early  forms.  The  Cycad  genus,  Dioonites 
(Fig.  1350),  occurs  in  the  Neocomian  of  Europe  (at  Wernsdorf),  and  is  very 
common  in  the  Potomac  beds.  Fontaine  says,  in  his  conclusion,  that  the 
flora  ranges  from  the  Wealden  through  the  Neocomian,  and  includes  some 
later  (Cenomanian)  forms.  All,  or  nearly  all,  the  species  are  absent  from 
the  later  Cretaceous  beds  of  New  Jersey. 


1350-1353. 


1353 


PLANTS  OP  THE  POTOMAC  GROUP. —CYCAD. —  Fig.  1350,  portion  of  a  frond  of  Dioonites  Buchianus.  ANGIO- 
6PERM8.  —  Fig.  1351,  Ficus  Virginiensis ;  1352,  Protseiphyllum  reniforme.  FERN.  —  Fig.  1853,  Sphenopteris 
Mantelli.  All  from  Fontaine. 

The  plants  of  the  Trinity  beds  of  Texas  are  to  a  large  extent  identical, 
according  to  Fontaine,  with  those  of  the  lower  Potomac  beds  (1893).  They 
include  Cycad  stumps  named  Oycadeoidea  munita  by  Cragin.  Cycadeoidea 
Jenneyana  of  L.  F.  Ward  occurs  in  the  form  of  stumps  at  the  Black  Hills,  on 


MESOZOIC   TIME  —  CRETACEOUS. 


833 


the  western  border  of  South  Dakota,  in  beds  that  are  shown  by  Ward  to  be 
Lower  Cretaceous,  though  formerly  referred  to  the  Dakota  group. 

The  flora  of  the  Kootanie  beds,  in  British  America,  described  by  Dawson, 
includes  no  Angiosperms  ;  but  the  identity  of  other  species  with  some  of 
those  of  the  Potomac  group  is  regarded  as  sufficient  evidence  of  equivalency. 
Some  of  the  kinds  are  here  represented.  Fig.  1354,  Sequoia  Smittiana  of 
Heer,  common  in  the  Greenland  beds;  1355,  Salisburia  Sibirica,  a  species 
described  by  Heer  from  the  Lower  Cretaceous  of  Greenland ;  and  1356,  the 
Cycad,  Podozamites  lanceolatus  Lindley,  a  species  that  is  found  also  in  Siberia, 
Sweden,  India,  and  China,  and  appeared  first  in  the  Jurassic.  The  same  species 
occur  in  the  Kootanie  beds  of  Montana,  as  first  observed  by  Newberry. 
Cretaceous  plants  from  Cape  Lisburne,  Alaska,  were  referred  by  Lesquereux, 
in  1888,  to  the  Neocomian.  The  number  of  species  thus  far  described  from 
the  region  is  60  (Knowlton).  The  Koine  beds  of  Greenland  afforded  Heer 
species  of  Ferns,  Cycads,  Conifers,  a  few  Endogens,  and  but  one  Angiosperm, 
Populus  primceva. 

The  plants  of  the  Kootanie  beds  include,  according  to  Dawson,  besides  those  of 
Figs.  1354-1356,  Dioonites  borealis  Dawson,  Zamites  Montana  Daws.,  Z.  acutipennis 


1354-1366. 


1354 


1355 


KOOTANIE  PLANTS.  —  CONIFERS —  Fig.  1354,  Sequoia  Smittiana ;  1355,  Salisburia  Sibirica.    CYCAD.  —  Fig.  1356, 
Podozamites  lanceolatus.     J.  W.  Dawson. 

Heer,    Salisburia  nana  Daws.,    Baiera    longifolia  Heer,    Glyptostrobus   Groenlandicus 
Heer,  Taxodium  cuneatum  Newberry.     (Heer's  species  are  all  Greenland  species.)     From 
DANA'S  MANUAL  —  53 


834 


HISTORICAL   GEOLOGY. 


Queen  Charlotte  Islands  he  has  announced  Dioonites  Columbianus  Dawson.  From  the 
Kootanie  beds  of  Montana  at  Great  Falls,  Newberry  has  described  (1891)  25  species  of 
plants,  and  among  them,  Zamites  Montana,  Z.  acutipennis,  Z.  borealis  Heer,  Z.  apertus 
Newberry,  Podozamites  nervosus  Newb.,  Sequoia  Smittiana  Heer,  S.  gracilis  Heer,  8. 
fieichenbachi  Heer,  and  Sphenolepidium  Virginicum  Fontaine.  The  last  two  are  also 
found  in  the  Potomac  group.  From  the  Trinity  group  of  Texas,  Fontaine  has  identified 
some  Neocomian  species :  as  Dioonites  Buchianus,  D.  Durikerianus,  Abietites  Linkii, 
and  a  species  very  near  Sphenopteris  Valdensis,  besides  several  other  species  that  occur 
in  the  Potomac  group. 


1357. 


KHIZOPOD.  —  Patellina 
Texana.     Koetner. 


1358. 


ANIMALS.  —  Marine  fossils  are  confined  almost  solely  to  the  beds  of  Texas 
and  Mexico,  and  the  Pacific  Coast  region;  and  these  two  regions  widely  differ  in 
fauna.  The  former  was  apparently  tropical,  while  the 
latter  bears  evidence  of  cooler  waters,  just  as  the  Mexican 
Gulf  and  California  seas  now  differ.  At  present  this  dif- 
ference (as  shown  on  the  isocrymal  chart,  page  47)  is 
about  16°  F.,  owing  to  the  cold  currents  that  descend  the 
Pacific  coast  from  the  north;  and  it  was  probably  10°  or 
12°  in  Cretaceous  times,  when  like  species  occurred  on  that 
coast  from  California  to  Alaska. 

Texas.  —  The  Comanche  beds  are  largely  made  of  the 
minute  shells  of  Rhizopods,  and  also  contain  the  larger 
Nummulite-like  fossil,  the  Patellina  (Orbitulites)  Texana  (Fig.  1357).  Echi- 
noderms  are  represented  by 
species  of  Enallaster  (Fig. 
1358) ,  Pseudodiadema,  Hemi- 
aster,  Cidaris,  etc. ;  Brachio- 
pods,  by  species  of  Terebra- 
tula. 

Lamellibranchs  occur  of 
the  genera  Gryphcea  (Fig. 
1359),  Exogyra  (Fig.  1360), 
Lima,  Inoceramus,  which  are 
very  common.  Some  speci- 
mens of  Exogyra  ponderosa 
in  Texas  are  nine  inches  long, 

and  the  shell  four  inches  thick  at  middle.  Two  species  of  genera  related 
to  the  modern  Chama,  peculiar  to  the  Cretaceous,  are  Radiolites  Texanus  (Fig. 
1361,  1361  a),  reduced  from  a  length  of  4J-  inches,  and  Requienia  (Caprina) 
Texana  (Fig.  1362).  The  genus  Nerinea  (Fig.  1363)  is  also  characteristic 
of  the  Cretaceous. 

Of  the  fossils  of  the  Shasta  group,  California,  the  Aucellce  are  especially 
characteristic.  The  forms  vary  much,  but  all  are  referred  to  one  species 
named  by  Gabb,  A.  Piochii.  Fig.  1364  represents  a  common  form  of  the 
shell,  and  Fig.  1365,  the  smaller  valve  of  a  specimen.  Another  specimen 
figured  has  a  height  of  more  than  two  inches,  while  but  little  wider  than 


Ecu  INODEKM. —Enallaster  Texanus,   upper  and  under    surface. 
Koemer. 


MESOZOIC   TIME  —  CRETACEOUS. 


835 


Fig.  1365.     The  shells  are  in  great  profusion  in  many  localities,  and  are  often 
associated  with  Belemnites  appressus.     Fig.  1366  is  from  a  small  shell  from 


1361  a 


1359-1363. 


1360 


LAMELLIBRANCHS.  —Fig.  1359,  Gryphaea  Pitcher!  of  Morton;  1360,  Exogyra  arietina  ;  1361,  Radiolites  Texanus, 
without  upper  valve  (x  $) ;  1361  a,  the  lid-like  upper  valve  ;  1362,  Kequienia  Texana.  GASTROPOD.  —  Fig. 
1363,  Nerinea  Texana.  All  from  Roemer. 


1364-1366. 


1364 


1365 


1366 


MOLLUSK.  —  Figs.  1364-1366,  Aucella  Piochii.    Gabb. 


Mt.  Diablo,  where  they  are  rare.  The  shells  fail  entirely,  or  very  nearly  so, 
of  the  radiating  striae  which  characterize  the  Jurassic  Aucella  of  Mariposa 
(page  759). 


836 


HISTORICAL   GEOLOGY. 


Vertebrates.  —  Some   scales   of   Ctenoid  fishes  have  been   found  in  the 
Potomac  beds.     But  the  Vertebrates  of  special  interest  are  the  large  Reptiles : 

a  species  related   to   the 
1367-1368. 
1367 


1368 


DINOSAURS.  —  Fig.  1367,  Vertebra  of  Pleurocoelus  nanus  ;  1368,  tooth  of 
Priconodon  crassus.     From  Marsh. 


Morosaurus,  the  Astrodon 
Johnstonii  of  Leidy  (1865); 
and  the  other  Dino- 
saurs Pleurocoelus  nanus, 
P.  altus,  Priconodon  cras- 
sus, Allosaurus  (?)  medius, 
and  Coelurus  gracilis,  de- 
scribed by  Marsh  (1888). 
Fig.  1367  represents  a 
side  view  of  one  of  the 
dorsal  vertebrae  of  Pleu- 
rocoelus nanus,  and  1368, 
an  inside  view  of  a  tooth 

of  Priconodon  crassus.     On  account  of  the  Jurassic  features  of  the  Reptiles, 
the  Potomac  group  has  been  referred  by  Marsh  to  the  Upper  Jurassic. 

From  the  Lower  Cretaceous  of  Texas  and  its  continuation  into  Oklahoma 
(formerly  Indian  Territory)  five  species  of  Pycnodont  Fishes  have  been 
described  by  Cope :  Mesodon  diastematicus,  M.  Dumblei,  and  two  species  of 
Uranoplosus  and  one  of  Cododus. 

Characteristic   Species. 

The  fauna  of  Texas  (and  the  country  beyond  to  Mexico)  has  special  interest,  because 
the  region  is  the  only  one  of  the  Lower  Cretaceous  in  North  America  abounding  in  marine 
fossils.  The  characteristic  species  are  as  follows,  according  to  Hill : 

1.  Trinity  group. — The  Glen  Hose  beds  have  afforded:   Ostrea  Franklini  Coquand, 
Modiola  Branneri  Hill,  Pecten  Stantoni  Hill,  Eequienia  Texana,  Barbatia parva  Missouri- 
ensis,   Isocardia    medialis    Conrad,    Natica   pedernalis    Roamer,    Nerinea    Austinensis 
Roemer;  also,  Crocodiles,  Dinosaurs,  Chelonians,  and  Fishes  not  yet  studied.     A  bed  of 
chalk  is  composed  of  the  Rhizopod  Patellina  (Orbitulites)   Texana  R.  (Fig.  1357). 

2.  Fredericksburg  group.  —  The  prominent  fossils  of  its  several  subdivisions  are  the 
following:      (1)   The    Gryphcea  rock  and    Walnut  sands:    Exogyra    Texana  R.    (  =  E. 
flabellata  Goldfuss) ;  and,  higher  up,  a  bed  made  up  of  Gryphcea  Pitcheri  (the  small  form 
figured  by  Conrad).     (2)  The   Comanche   Peak  chalk:    Pseudodiadema     Texanum  R., 
Enallaster  Texanus  R.,  Exogyra  Texana,  Gryphcea  Pitcheri  Conrad  (not  Marcou),  Janira 
occidentalis    Con.,    Protocardium    Hillanum    Sowerby,    Nerinea  acus  R.,   Ammonites 
(Buchiceras)  pedernalis   R.     (3)  The    Caprina   limestone,  also  called  the  "  Hippurite " 
limestone:    Nerinea     Austinensis    R.,    N.    cultrispira    R.,    N.    subula    R.,    Cerithium 
Austinense  R.,  Trochus  Texanus  R.,  Solatium planorbis  R.,  Monopleura  marcida  White, 
M. pinguiscula  White,  Eequienia  patagiata  White,  Ichthyosarcolithes  (Caprina}  anguis 
R.,  I.  (?)  crassifibra  R.,  /.  ( ?)  planatus  Con.,  Eadiolites  (Sphcerulites)  Texanus  R. 

3.  Washita  group.  —  (1)  The  Preston   beds,    Schlcenbachia  clays,   including  lime- 
stone flags,    Gryphcea  forniculata   White    (  =  G.  Pitcheri  Marcou),  and  the  Ammonite 
Schlcenbachia  Peruviana  v.  Buch.  ;   the  limestone  is  the  building  material  of  old  Fort 
Washita.     (2)    The   Duck    Creek  chalk,  many  Ammonoids,  among  them   Pachydiscus 
Brazoensis  Shum.,  Schlcenbachia  Belknapi  Marcou,  and  Hamites  Fremonti  Marcou  ;  with 


MESOZOIC   TIME  —  CKETACEOUS.  837 

Isocardia  Washita  Marcou,  Inoceramus,  Terebratula  Choctawensis  Shum.  (3)  The  Fort 
Worth  or  Washita  limestone :  with  Terebratula  Wacoensis  R.,  Cidaris  Texana  R., 
Leiocidaris  hemigranosa  Shum.,  Holectypus  planatus  R.,  Epiaster  elegans  Shum. ,  Holaster 
simplex  Shum.,  Ottrea  carinata  Lam.,  Exogyra  sinuata  Marcou,  Gryphcea  Pitcheri 
Morton,  Janira  Wrightii  Shum.,  Plicatula  placunea  d'Orb.,  Pleurotomaria  Austinensis 
Shum.,  Lima  Kimballi  Gabb,  Nautilus  elegans  Shum.,  Ammonites  (Mortoniceras) 
Leonensis  Con.,  Turrilites  Brazoensis  R.  (4)  The  Denison  Beds  of  clays  and  limestone: 
having  at  base  Exogyra  arietina  R.,  Ostrea  quadruplicata  Shum.,  Gryphcea  Pitcheri  R. 
(not  Morton,  which  is  G.  mucronata  Gabb),  the  Ammonites  Buchiceras  inceqiiiplicatnrn 
Shum.,  Hoplites  Deshayesi  Leym.,  and  many  other  species.  Turbinolia  Texana  is 
abundant  in  the  western  exposures  of  the  Denison  beds,  and  the  Rhizopod,  Nodosaria 
Texana  Con.,  occurs  throughout  them. 

Hill  concludes  from  the  fossils  that  the  Trinity  group  is  closely  related  in  age  to  the 
Wealden  of  Europe,  and  the  Washita  to  the  Lower  Greensand  or  Gault. 

The  Horsetown  beds  of  California  have  afforded  many  species,  described  chiefly  by  Gabb 
andTrask.  Among  them  are:  Pecten  operculiformis,  Pleuromya  Icevigata,  Nemodon  Van- 
couverensis,  Nerita  deformis,  Nerinea  dispar,  Neithea  grandicostata,  Lima  Shastaensis,  and 
the  Ammonites  Desmoceras  Breweri,  Lytoceras  Batcsii,  Pachydiscus  Whitneyi,  Olcoste- 
phanus  Traskii,  Ancyloceras  Remondi,  etc.  The  first  three  Ammonites  occur  in  the  Queen 
Charlotte  group,  according  to  Whiteaves. 

The  Knoxville  beds  are  characterized,  according  to  the  latest  researches  of  Hyatt, 
Stanton,  and  Diller,  by  its  Aucella,  Ammonites,  and  a  few  other  fossils,  which  show  close 
relations  to  the  Horsetown  beds  and  a  wide  divergence  from  the  Mariposa  beds. 

The  Potomac  beds  have  afforded  a  few  rare  marine  shells.  Whitfield  mentions  Astarte 
veta,  Ambonicardia  Cookii,  Corbicula  emacerata,  C.  annosa  (Astarte  annosa  Conrad),  and 
Gnathodon  tenuides,  besides  6  species  of  Unto  and  Anodonta. 

2.   UPPER  CRETACEOUS. 

PLANTS.  —  In  the  Upper  Cretaceous,  leaves  of  Cycads  are  comparatively 
rare,  while  those  of  Angiosperms  are  of  great  variety ;  and  to  these  are  added 
the  leaves  or  fronds  of  Palms. 

Some  of  the  prominent  kinds  in  the  new  flora  were  species  of  Sassafras, 
Laurus,  Liriodendron  (Tulip  Tree).  Magnolia,  Aralia,  Cinnamomum,  Sequoia, 
the  Poplar,  Willow,  Maple,  Birch,  Chestnut,  Alder,  Beech,  Elm,  etc.  A  leaf 
of  a  Palm  (Sabal)  from  Vancouver  Island  is  described  by  Newberry  as  8  to 
10  feet  in  diameter.  Dawson  gives  an  interesting  review  of  the  Sequoias  in 
his  Geological  History  of  Plants — a  genus  of  many  species  then,  but  now 
of  only  2,  and  these  exclusively  North  American. 

The  leaves  of  Angiosperms,  here  figured,  are  all  from  the  Dakota  beds,  or 
their  probable  equivalent,  on  the  Atlantic  border,  the  Karitan  clays  of  New 
Jersey,  Martha's  Vineyard,  and  Long  Island.  Fig.  1369  represents  a  leaf 
of  Sassafras  Cretaceum  Newb.,  of  the  Dakota  group ;  1370,  the  leaf  of  a  Tulip 
Tree,  Liriodendron  Meekii  Heer,  from  Greenland  (Atane  group)  and  the 
Dakota ;  1371,  L.  simplex  Newb.,  from  the  Amboy  clays  of  New  Jersey,  Long 
Island,  and  Gay  Head,  Martha's  Vineyard, — the  figure  from  a  leaf  of  the 
latter  locality ;  1372,  an  Andromeda,  from  Gay  Head,  a  kind  found  also  in 
Greenland  and  the  Dakota  group ;  1373,  a  Myrsine  of  Gay  Head,  and  likewise 
a  Greenland  species;  1374,  a  Willow,  Salix  Meekii  Newb.,  of  the  Dakota; 


HISTORICAL   GEOLOGY. 


and  1375,  Eucalyptus  Geinitzi  Heer,  from  Gay  Head,  also  occurring  in  Green- 
land, Bohemia,  and  Moravia,  —  a  genus  now  mostly  confined  to  Australia. 
Fig.  1376  represents  a  nut  of  the  Eucalyptus.  D.  White,  the  describer  of  the 
Gay  Head  plants  (1890),  states  that  these  nuts  contain  in  their  furrows  an 
amber-like  resin,  and  suggests  that  the  Eucalyptus  Tree  may  have  been  the 
source  of  the  "amber"  of  the  Gay  Head  and  New  Jersey  regions. 


1372 


1373 


1369-1376. 


1371 


ANGIOSPERMS.  —  Fig.  1869,  Sassafras  Cretaceum  ;  13TO,  Liriodendron  Meekii ;  1371,  L.  simplex  ;  1372,  Andromeda 
Parlatorii ;  1373,  Myrsine  borealis  ;  1874,  Salix  Meekii ;  1375,  Eucalyptus  Geinitzi ;  1876,  nut  of  Eucalyptus. 
Figs.  1369,  1370,  1374,  Newberry ;  others,  D.  White. 

Coccoliths,  calcareous  disks  less  than  a  hundredth  of  an  inch  in  diameter 
(page  437),  which  are  now  common  over  the  bottom  of  the  deep  oceans,  con- 
tributed to  the  Cretaceous  limestones,  and  are  abundant  in  the  Cretaceous  of 
the  east  slope  of  the  Rocky  Mountains. 

In  the  clays  of  Gay  Head,  on  Martha's  Vineyard,  the  most  eastern  Cretaceous  region 
of  the  continent,  D.  White  identified  Sphenopteris  Grevillioides  Heer,  of  the  Rome  beds, 
Greenland ;  Sequoia  ambigua  Heer,  Kom6  and  the  Lower  AtanS  (or  Middle  Cretaceous)  ; 
Andromeda  Parlatorii,  Lower  Atane ;  and  also  a  Sapindus,  near  S.  Morrisoni  of  Lesque- 
reux,  a  Dakota  and  Greenland  species. 


MESOZOIC   TIME  —  CRETACEOUS. 


839 


A  report  by  J.  S.  Newberry,  on  the  plants  of  the  Raritan  group  of  the  Atlantic  border, 
nearly  ready  for  publication  at  the  time  of  his  death  in  1892,  has  not  yet  appeared  (1894). 
A  few  Long  Island  species  have  been  described  and  figured  by  A.  Hollick  (1892-93). 
They  were  from  the  clays  on  the  north  side  of  the  island  between  Eaton's  Neck  and  Glen 
Cove. 

An  account  of  the  plants  of  the  Dakota  group  is  contained  in  Lesquereux's  quarto 
reports  —  one  volume  published  in  connection  with  the  reports  of  the  Hayden  Expedition, 
and  another  posthumous  volume,  edited  by  F.  H.  Knowlton,  published  as  vol.  xvii.  of 
the  Memoirs  of  the  U.  S.  Geological  Survey  (1893).  The  flora,  so  far  as  now  known,  in- 
cludes 429  Angiosperms,  8  Endogens,  15  Conifers,  12  Cycads,  and  6  Ferns ;  in  all  470 
species.  As  Knowlton  states,  the  proportion  of  Cycads  is  nearly  the  same  as  in  the  AtanS 
group  of  Greenland  described,  by  Heer,  while  the  Angiosperms  make  91  per  cent  of  the 
whole  and  in  the  AtanS  group  72  per  cent ;  and  a  fourteenth  of  the  whole  are  identical 
with  Greenland  species.  The  spirally  marked  fruit  of  a  Chara,  C.  Stantoni,  has  been 
found  by  Knowlton  in  the  Bear  River  beds. 

The  Laramie  plants  also  were  described  by  Lesquereux  in  one  of  the  quarto  volumes 
of  the  Hayden  Expedition  reports.  But  it  is  found  that  there  is  some  uncertainty  with 
regard  to  localities,  and  the  subject  is  undergoing  revision.  They  include  no  Cycads. 

The  following  lists  of  characteristic  species  of  the  Laramie  and  Denver  groups  are  from 
F.  H.  Knowlton  :  — 

Fossil  plants  characteristic  of  the  Lower  Laramie  :  Musophyllum  complicatum,  Flabel- 
laria  eocenica,  Ficus  lanceolata,  Ficus  latifolia,  Quercus  angustiloba,  Sterculia  modesta, 
Anona  robusta,  Dombeyopsis  squarrosa,  Nelumbium  tenuifolium,  Bhamnus  salicifolius, 
Cornus  suborbifera. 

Fossil  plants  characteristic  of  the  Denver  group :  Osmunda  affinis,  Asplenium  erosum 
(Pteris  erosa  Lx.),  Aspidium  Lakesii,  Woodwardia  latiloba,  Oreodoxites  plicatus,  Ficus 
occidentalis,  F.  spectabilis,  Populus  Nebrascensis  (varieties),  Fraxinus  eocenica,  Zizyphus 
fibrillosus,  Ehamnus  Goldianus^Platanus  Eaynoldsii,  Viburnum  Goldianum. 

Fossil  plants  common  to  both  the  Lower  Laramie  and  Denver  groups :  Ficus  plani- 
costata,  Dombeyopsis  obtusa,  Paliurus  zizyphoides,  Artocarpus  Lessigiana. 

The  plants  of  the  Livingston  beds,  referred  by  Weed  and  Knowlton  to  the  Denver 
horizon,  are  the  following  (U.  S.  G.  S.  Bulletin,  No.  105,  1893).  They  are  stated  to  be, 
by  Weed,  from  the  lower  300'  of  the  beds.  Those  species  that  occur  also  in  the  Lower 
Laramie  beds  are  designated  by  Lar. ;  those  in  the  Denver  group  of  the  Denver  region, 
by  the  letter  D ;  and  those  that  are  known  from  the  Miocene  Tertiary,  by  the 
letter  M :  — 


Abietites  dubius  Lesquereux Lar. 

Sequoia  Reichenbachi  Geinitz Lar. 

Taxodium  distichum  Miocenum  Heer. 
Ginkgo  adiantoides  Ung. 
Phragmites  Alaskanus  Heer. 

Caulinites  sparganioides  Lx Lar. 

Populus  mutabilis  ovalis  Heer Lar. 

"       Isevigata  Lx D. 

Salix  angusta  Al.  Br Lar.,  M. 

Quercus  castanopsis  Newb. 
Godeti  ?  Heer. 

"       Ellisiana  Lx Lar. 

Juglans  rugosa  Lx Lar.,  D.,  M. 

"       denticulata  Lx D.,  M. 

"       rhamnoides  Lx Lar.,  D. 


Platanus  Guillelmse  Goppert. .  .Lar.,  D.  M. 

?     "        aceroides  Goppert D.,  M. 

Ficus  auriculata  Lx D. 

?   "    tiluefolia  (Al.  Br.)  Heer. . .  Lar.,  D. 

"    planicostata  Lx Lar.,  D. 

Cinnamomum  Scheuchzeri  ?  Heer. 
"  ellipticum  Knowlton. 

Litsaea  Weediana  Knowlton. 

Laurus  socialis  Lx type  from  Lar. 

Fraxinus  denticulata  Heer Lar.? 

Andromeda  affinis  Lx. 

?  Nyssa  lanceolata  Lx D. 

Rhamnus  rectinervis Lar.,  D. 

"        salicifolius  ?  Lx Lar. 

Celastrinites  laevigatus  Lx. 


840 


HISTORICAL   GEOLOGY. 


1379 


1377-1379. 


1377 


The  fossil  plants  of  the  Dun  vegan  group  of  northern  Canada  (north  of  55°  N.)  con- 
tain, according  to  Dawson,  species  of  Magnolia,  Laurus,  Ficus,  Quercus,  Fagus,  Setula, 
Sequoia,  and  Cycads,  and  are  referred  to  the  age  of  the  Niobrara.  The  plant-bearing  Mill 
Creek  beds  overlying  the  Lower  Cretaceous  of  the  Queen  Charlotte  Islands  are  made 
Dakota  in  age ;  and  the  Coal-measures  of  Vancouver  Island  are,  on  the  same  authority, 
of  the  age  of  the  Montana  group.  Dawson  refers  to  this  time  Heer's  Patoot  flora  of 
Greenland.  He  compares  this  flora  with  that  of  Georgia,  and  from  the  general  resemblance 
in  genera  infers  that  the  temperature  of  the  region  may  have  been,  like  that  of  Georgia, 
about  65°  F.  The  Laramie  flora,  he  observes,  is  most  remarkable  for  its  Conifers,  Taxites, 
Sequoia,  Thuia,  etc.,  and  for  the  great  development  of  the  genus  Platanus  ;  also  for  con- 
taining some  modern  species  of  Ferns,  as  Onoclea  sensibilis,  Davallia  tenuifolia. 

References  to  all  papers  and  reports  on  fossil  plants  published  before  1884  will  be 
found  in  Ward's  Sketch  of  Palseobotany,  U.  S.  G.  /S.  Ann.  Hep.,  vol.  v. 

ANIMALS.  —  Invertebrates.  —  The  shells  of  Rhizopods,  or  Foraminifers, 
are  abundant  in  many  of  the  beds  in  New  Jersey,  and  still  more  so  in  those  of 
Texas.  Sponges  are  thus  far  rare  fossils  in  the  beds.  Corals  are  not  numerous. 

One  from  the  Ripley  beds  of  Texas, 
described  and  figured  by  C.  A.  White, 
is  represented  in  Fig.  1377.  No 
coral  reefs  have  been  reported  ;  but 
they  may  possibly  exist  underneath 
the  Tertiary  of  some  part  of  the 
Gulf  or  Atlantic  border.  Echinoids 
occur  of  the  genera  Cidaris,  Salenia, 
Cassidulus,  Holaster,  Hemiaster,  and 
others.  Less  than  35  Upper  Creta- 
ceous species  are  known  from  all 
North  America,  while  Great  Britain 
has  afforded  nearly  150. 

Brachiopods  are  few  in  species. 
The  two  here  figured,  Terebratella 
plicata  (Fig.  1378),  and  Terebratula 
Harlani  (Fig.  1379)  of  Morton,  are  quite  common  in  New  Jersey.  Meek 
described  only  one  Lingula,  L.  nltida,  from  the  Upper  Cretaceous  of  the 
Continental  Interior,  and  this  was  from  the  Fox  Hills  group.  The  contrast 
in  species  between  the  closing  period  of  the  Mesozoic  and  that  of  the  Paleo- 
zoic is  in  no  tribe  more  marked. 

Of  the  characteristic  Lamellibranchs  there  are,  in  the  0}7ster  family,  the 
genera  Ostrea  (Figs.  1380,  1381),  Gryphcea  (Figs.  1384,  1385),  and  Exogyra 
(Fig.  1383)  ;  and  in  the  Avicula  family,  Inoceramus,  L  labiatus  (Fig.  1386) 
being  very  common. 

The  Rudistes,  one  Neocomian  species  of  which  is  figured  on  page  835 
(Fig.  1361),  are  very  rare  fossils  in  America  in  the  Upper  Cretaceous.  Fig. 
1387  represents  one  species  described  by  C.  A.  White  from  the  Wallala 
section  of  the  Chico  beds  of  California.  Other  Gastropods  of  modern 
forms  are  represented  in  Figs.  1388-1392. 


1378 


COBAL.  —  Fig.  1377,  Hindeastraea  discoidea.  BRACIIIO- 
PODS.  —  Fig.  1378,  Terebratella  plicata ;  1379,  Tere- 
bratula Harlani.  Fig.  1377,  C.  A.  White;  1378, 
1379,  Morton. 


MESOZOIC   TIME  —  CRETACEOUS. 


841 


Cephalopods  of  the  tribes  of  Belemnites  and  Ammonoids  are  of  many 
species.     One  of  the  most  common  of  the  Belemnites,  common  to  New  Jersey, 


1380 


1382 


1380-1386. 


1384 


LAMELLIBRANCHS.  —  Fig.  1380,  Ostrea  congesta;  1381,  Ostrea  larva  ;  1382,  Inoceramus  dimidius  ;  1383,  Exogyra 
costata ;  1384,  Gryphaea  vesicularis ;  1385,  G.  Pitcher! ;  1386,  Inocerainus  labiatus  (formerly  problematicus). 
Fig.  1380,  1382,  Stanton  ;  1381,  D'Orbigny ;  1383-1385,  Meek  ;  1386,  Kcemer. 


138 


1387-1392. 

1392a 


13926 


LAMELLIBRANCH.  —  Fig.  1387,  Coralliochama  Orcutti  (x  |).  GASTROPODS.  —  Fig.  13S8,  Pyrifusus  Newberryi ; 
13S9,  Fasciolaria  buccinoides  ;  1390,  Anchura  (Drepanocheilus)  Americana;  1391,  Margarita  Nebrascensis  ; 
1392  a,6,  Eulla  speciosa.  Fig.  1387,  C.  A.  White  ;  1388-1392,  Meek. 

Texas,  and  the  Upper  Missouri,  is  represented  in  Fig.  1393.  Fig.  1394 
represents  the  Ammonite,  Placenticeras  placenta  of  Dekay ;  1394  a,  the  same 
in  side  view ;  and  1394  6  shows  the  flexures  in  the  partition  at  the  sutures ; 


842 


HISTORICAL   GEOLOGY. 


specimens  of  this  species  have  been  found  measuring  more  than  two  feet  in 
diameter. 

Among  the  more  or  less  uncoiled  Arnmonoids  there  are :  Fig.  1395,  the 
Scaphites,  S.  Conradi,  from  the  Fox  Hills  group,  which  is  sometimes  six  feet 


CEPHALOPODS.  —  Fig.  1393,  Belemnitella  Americana;  1394,  o,  6,  Placenticeras  (Ammonites)  placenta;  1395, 
Scaphites  Conradi ;  1896,  S.  larvaeformis ;  1397,  1397  a,  Baculites  ovatus  ;  1398,  young  stage  of  B.  com- 
pressus ;  1898  a,  same,  with  outer  layer  of  shell  removed,  showing  sutures  ;  1399,  section  of  B.  compressus, 
reduced ;  1400,  Nautilus  Dekayi.  Figs.  1393-1397,  1399,  1400,  Meek  ;  1398,  1898  a,  A.  P.  Brown. 


MESOZOIC   TIME  —  CKETACEOTJS. 


843 


long ;  and  1396,  S.  larvceformis,  another,  showing  more  decidedly  the  imper- 
fectly coiled  condition,  from  the  Fort  Benton  group.  Fig.  1397  is  an  Amino- 
noid  in  which  the  form  is  straight,  and  hence  the  name  Baculites,  from 
the  Latin  baculum,  a  walking-stick.  The  length  of  this  Baculite  is  over  a 
foot,  and  the  diameter  2^  inches ;  other  associated  species  are  more  than  a 
yard  long.  Another  species,  common  in  New  Jersey,  is  the  B.  compressus 
Say,  and  Fig.  1399  is  a  section  of  it.  A  young  stage  of  it  is  represented, 
enlarged,  in  Figs.  1398,  a,  by  A.  P.  Brown  (1891)  ;  the  specimens  were  from 
the  Black  Hills,  S.  D. ;  they  show  that  the  animal  in  the  young  stage  has  a 
perfectly  coiled  shell.  Others  of  these  partly  uncoiled  kinds  are  represented 
on  page  862.  Fig.  1400  is  a  Nautilus  from  the  Lower  Greensand,  New 
Jersey. 

Vertebrates.  —  1.  Fishes.  —  In  addition  to  Selachians  and  Ganoids  there 
were  Teleosts,  or  Osseous  Fishes,  the  tribe  which  includes  the  larger  part 
of  modern  fishes,  and  nearly  all  edible  species.  The  Cestraciont  Sharks 
still  continue ;  and  the  bony  pavement  .pieces  of  the  mouth  are  not  rare 
fossils.  Two  views  of  one  from  New  Jersey  are  given  in  Figs.  1406,  1406  a. 


1401-1406. 


1406 


1403 


1401 


SQUALODONT  SELACHIANS.  —  Fig.  1401,  Otodus  appendiculatus ;  1402  a,  6,  Lamna  Texana;  1403,  Corax  hetero- 
don  ;  1404,  Otodus  appendiculatus ;  1405,  Oxyrhina  Mantelli.  CESTEACIONT  SELACHIAN.  —  Figs.  1406,  1406  o, 
Ptychodus  Mortoni.  Fig.  1401,  Gibbes ;  1402-1405,  Rcemer ;  1406,  Morton. 

Many  of  the  Sharks  were  of  the  modern  tribe  of  Squalodonts  —  distinguished 
by  the  sharp  cutting  edges  of  the  teeth,  and  other  peculiarities.  One  kind 
is  represented  in  Figs.  1401  and  1404  of  the  genus  Otodus,  the  latter  from 
Texas;  1403,  tooth  of  a  Corax;  1405,  of  an  Oxyrhina;  1402  a,  6,  of  Lamna 
Texana. 

The  Teleosts  of  the  Middle  and  Upper  Cretaceous  of  North  America  in- 
clude species  of  the  Mullet  family,  represented  by  Beryx  insculptus  Cope, 
from  New  Jersey  ;  the  Sphyrenids  of  several  large  species  described  by  Cope, 
of  the  genera  Pachyrhizodus,  Empo,  and  others,  from  Kansas  ;  the  Siluroids, 
powerful  carnivorous  fishes,  called  Saurodonts  by  Cope,  one  of  which,  Por- 
theus  molossus  Cope,  from  Kansas,  had  the  vertical  diameter  of  the  head 


844 


HISTORICAL  GEOLOGY. 


nearly  two  feet.  They  appear  to  have  been  among  the  most  formidable 
of  all  Teleosts.  Saurocephalus  lanciformis  Harlan  (Saurodon  lanciformis 
Hays,  1830),  from  the  "  Upper  Missouri  region,"  is  one  of  the  group. 


1407 


Restoration,  showing  the  probable  form  of  Portheus,  Cope. 

2.  Reptiles.  —  The  Reptiles  included  species  of  enormous  size,  yielding  to 
few  if  any  of  the  Jurassic  period.    Besides  long-necked  Sea-Saurians,  related  to 

1408. 


Restoration  of  Claosaurus  annectens  (x^).     Marsh. 


the  Plesiosaurs,  and  huge  carnivorous  and  herbivorous  Dinosaurs,  related  to 
the  older  kinds,  there  were  other  Dinosaurs  equally  huge,  having  horns  with 
horn-cores,  like  cattle,  but  with  a  third  horn  on  the  nose  ;  Pterosaurs,  20  feet 


MESOZOIC   TIME  —  CRETACEOUS. 


845 


and  upward  in  span  of  wings ;  and,  as  a  new  feature,  great  Sea-serpents,  the 
Mosasaurids,  having  a  length  of  10  to  80  feet. 

Plesiosaurids  of  the  genus  Cimoliosaurus  of  Leidy  (1865)  have  been  found 
in  New  Jersey,  Alabama,  and  Mississippi,  and  others,  of  the  genus  Elasmo- 
saurus  of  Cope,  in  the  Continental  Interior.  The  E.  platyurus,  a  carnivorous 
species,  45  to  50  feet  in  length,  had  a  neck  22  feet  long,  containing  over  60 
vertebrae. 

The  Herbivorous  Dinosaurs  include  species  of  widely  diverse  forms  and 
great  magnitude.  The  first  discovered  is  the  Hadrosaurus  Fonlkii  of  Leidy 
(1858),  a  species  about  28  feet  long,  having  many  of  the  characters  of  the 
Iguanodon  of  Great  Britain. 

A  related  species,  equally  large,  is  the  Claosaurus  annectens  of  Marsh 
(1890),  from  the  Ceratops  beds  of  eastern  Wyoming,  of  which  a  restoration 
by  the  describer  is  here  given  (Fig.  1408). 

It  is  an  excellent  example  of  these  three-toed  Ornithopod  Reptiles,  with 
their  short  fore  feet,  and  very  massive  tail, — the  latter,  one  of  the  three 
supports  of  the  heavy  body  when  erecting  itself  for  brousing.  A  side  view 
of  the  skull  is  shown  in  Fig.  1409.  The  teeth  are  confined  to  the  maxillary 


1409-1411. 


1409 


1411 


CLAOSAUBUS  ANNECTENB.  —  Fig.  1409,  the  skull,  side  view  (x  TV)  ;  141°.  toP  view  (x 
a,  front  view  ;  6,  side  view(x  £).     From  Marsh. 


;  1411  a,  6,  series  of  teeth  : 


and  dentary  bones,  and  are  in  great  numbers  ;  they  are  arranged  in  vertical 
series,  and  Fig.  1411  is  an  outer  view  of  one  of  the  series,  in  which  the 
number  of  teeth  is  five.  The  number  of  teeth  in  the  series  is  largest  over 
the  middle  of  the  jaw,  and  is  sometimes  six  or  more.  Fig.  1410  is  an 
upper  view  of  the  skull.  At  b  is  the  brain  cavity,  which,  as  Marsh  states,  is 
very  small  in  proportion  to  the  head. 


846 


HISTORICAL  GEOLOGY. 


Another  species,  more  closely  like  Hadrosaurus,  is  the  Diclonius  mirabilis 
of  Cope  (1883;  Trachodon  mirabilis  of  Leidy,  1868),  from  the  Laramie  beds 
of  Dakota.  The  length  stated  is  38  feet,  and  that  of  the  head,  3£  feet. 


1412. 


DINOSAUR.  —  Triceratops  prorsus  (x  ^j).     Marsh. 


Widely  different  were  the  Herbivorous  Dinosaurs  of  the  family  Ceratop- 
sidae  of  Marsh,  —  species  of  great  magnitude,  having  the  horns  of  cattle  with 


1414 


1413-1415. 


1415 


DINOSAUBS.  —  Fig.  1413,  Tooth  of  Triceratops  prorsus,  showing  the  two  prongs  (natural  size)  ;  1414,  skull  of  T. 
serratus  (x  jfo  ?)  ;  1415,  skull  of  Torosaurus  gladius  (3V)-     Marsh. 


MESOZOIC    TIME  —  CRETACEOUS. 


847 


1416. 


the  beaked  mouth  of  a  Turtle,  or  rather  of  the  Khynchocephs  of  the  Trias. 
They  are  from  the  same  Laramie  beds  in  Wyoming  that  afforded  the  Clao- 
saurus,  and  occur  also  in  the  Denver  beds,  near  Denver,  Col.  (where  the  first 
specimen  was  found),  at  Black  Butte,  Wyoming,  and  in  the  Judith  River 
beds,  Montana.  The  restoration  by  Marsh  (Fig.  1412),  one  sixtieth  the 
natural  size,  shows  the  general  character  of  the  skeleton  of  these  strange 
but  stupid  inhabitants  of  the  waning  Mesozoic.  The  broad  cranium  (over 
eight  feet  long  in  one  species)  projects  far  over  the  neck,  like  the  posterior 
flap  of  some  forms  of  helmet,  and  sometimes  has  a  degree  of  decoration  in 
its  pointed  posterior  margin. 

The  teeth  had  two  prongs  (Fig.  1413),  a  Mammalian  feature  not  known 
in  other  Reptiles.  The  skull  of  another  species  of  the  genus  is  shown  in 
Fig.  1414 ;  and  of  a  third,  but  of  a  distinct  genus,  Torosaurus,  in  Fig.  1415. 
J.  B.  Hatcher,  who  procured  many  of  the  bones  described  by  Marsh,  gives 
evidence  (1893)  that  the  great  Dinosaurs  lived  in  the  region  where  they 
died ;  and  he  speaks  of  one  skeleton  of  Claosaurus  annectens  Marsh  (Fig. 
1408),  as  found  in  a  partially  erect  condition,  the  limbs  extended,  the 
ribs  in  natural  position  about  the  abdominal  and  thoracic  cavities,  and  every 
bone  in  its  natural  place,  showing  that  the  animal  had  been  mired  in  the 
quicksands.  Some  of  the  Ceratopsid  skulls, 
although  seven  to  eight  feet  long,  make  the 
centers  of  sandstone  concretions,  weighing  many 
tons. 

Other  genera  of  Ceratopsids  described  by 
Cope  are  Agathaumas,  Monoclonius,  and  Polyo- 
nax,  severally  from  Wyoming,  Montana,  and 
Colorado.  Agathaumas  sylvestris  is  from  the 
Laramie  of  Black  Butte  station  in  southern 
Wyoming. 

Carnivorous  Dinosaurs  were  represented  by  a 
number  of  species.  Loelaps  aquilunguis  of  Cope 
(1869),  from  the  Upper  Greensand,  New  Jersey, 
is  about  24  feet  long;  it  probably  could  stand 
nearly  erect.  L.  incrassatus  is  reported  by  him 
from  Montana,  and  also  from  the  Laramie  beds 
of  Red  Deer  River  in  British  America.  The 
Ornithomimus  of  Marsh  is  a  small  species  from 
the  Laramie  Ceratops  beds  of  Wyoming,  remark- 
ably bird-like  in  its  skeleton,  as  illustrated  in 
the  figure  (Fig.  1416).  It  probably  could  stand 
erect  like  a  bird. 

The  Mosasaurids,  or  Sea-serpents,  of  the  era, 
Pythonomorpks  of  Cope  (after  the  genus  Pytho), 

were  eminently  characteristic  of  the  Upper  Cretaceous.  Previous  to  the 
American  discoveries  of  their  remains,  knowledge  of  them  was  confined 


DINOSAUR.  —  Fig.  1416,  Ornithomi- 
mus velox,  2d,  3d,  and  4th  meta- 
tarsals,  natural  size ;  1416  a, 
phalanges  of  2d  digit.  Marsh. 


848  HISTORICAL   GEOLOGY. 

almost  solely  to  a  skull  found  in  the  uppermost  Cretaceous  beds  of  Belgium, 
on  the  river  Meuse,  1785,  whence  was  derived  the  name  Mosasaurus.  The 
first  American  species  was  a  tooth  in  a  fragment  of  a  jaw,  found  at  Mon- 
mouth,  N.  J.,  and  figured  in  S.  L.  Mitchill's  Geology  of  North  America, 
1818,  described  by  Dekay  in  1830,  and  named  Mosasaurus  major  by  him  in 
1841.  Previously  it  had  been  named  M.  Dekay i  by  Bronn  (1838).  The 
tooth,  according  to  Dekay,  was  1-06  inches  long  and  1-02  and  1-33  broad 
at  base.  Through  the  discoveries  since  made,  the  number  of  American 
species  described  is  near  50 ;  and  their  remains  have  come  from  the  borders 
of  the  Atlantic  and  the  Mexican  Gulf,  and  from  the  Interior  Continental 
seas  in  Kansas,  Dakota,  Colorado,  and  beyond.  Kansas  is  credited  with  25 
or  more  Mosasaurids  from  the  Niobrara  beds. 

The  species  are  related,  like  true  Snakes,  to  the  Lacertians ;  but  they  had 
paddles,  and  a  skulling  tail  which  was  nearly  half  the  length  of  the  body,  as 
shown  in  the  restoration  of  Edestosaurus  (Clidastes)  velox  of  Marsh,  by  S.  W. 
Williston,  in  the  following  figure.  The  Clidastes  iguanavus  of  Cope  is  from 

1417. 


Bestoration  of  Edestosaurus  (Clidastes)  velox  (x  ^).    Williston 


the  Lower  Greensand,  New  Jersey,  and  C.  propython  of  Cope,  from  the 
Rotten  Limestone  in  Alabama.  Baptosaurus  platyspondylus  and  B.  fraternus, 
both  of  Marsh,  are  from  the  Upper  Greensand  of  New  Jersey. 

One  of  the  fore  paddles  of  Lestosaurus  of  Marsh  is  represented,  much 
reduced,  in  Fig.  1420.  Fig.  1418  represents  the  tooth  of  Mosasaurus  princeps 
of  Marsh,  from  New  Jersey,  and  1419,  the  head  extremity  of  one  of  the 
Mosasaurids,  showing  the  bases  of  four  teeth.  An  anomaly  in  Mosasaurus  is 
the  existence  of  an  articulation  for  lateral  motion  in  either  ramus  of  the 
lower  jaw  (at  a  in  Fig.  1421),  where  there  is  in  all  other  Eeptiles  a  suture 
only  ;  a  fact  first  recognized  by  Cope.  Besides,  the  extremities  of  the  two 
rami  were  free,  so  that  they  could  serve  like  a  pair  of  arms  in  the  process  of 
swallowing  whole  a  large  animal. 

True  Snakes  are  rare  species  in  the  Mesozoic.  The  Coniophis  precedens 
of  Marsh,  the  only  one  known  in  this  country,  occurs  in  the  same  beds  with 
the  remains  of  the  Ceratopsidae  in  eastern  Wyoming. 

Crocodilians  were  represented  by  the  Thoracosaurus  of  Leidy  (the  New 
Jersey  Gauial,  or  Gavialis  Neocesariensis  of  De  Kay,  1833),  Holops  pneu- 
maticus  and  Gavialis  fraterculus,  of  Cope,  from  New  Jersey,  and  other  species 
having  the  vertebrae  concavo-convex,  as  in  true  Crocodiles.  The  older  type, 
with  biconcave  vertebrae,  also  was  represented;  and  Hyposaurus  Rogersi 
Owen  (1849)  from  New  Jersey,  and  H.  Webbii  Cope  from  Kansas  are  exam- 


MESOZOIC   TIME  —  CRETACEOUS. 


849 


pies.     Two  Lizards,  Chamops  segnis  Marsh,  and  Iguanavus  teres  Marsh  (1892), 
occur  in  Wyoming  in  the  beds  affording  the  Ceratops  remains. 


1418 


1418-1421. 
1419 


1420 


MOSASAITRIDS. —  Fig.  1418,  tooth  of  Mosasaurus  princeps  (x|);  1419,  snout  of  Tylosaurus  micromus,  showing 
bases  of  four  teeth  (x£);  1420,  right  paddle  of  Lestosaurus  simus  (x^j);  1421,  restored  jaw  of  Edestosaurus 
dispar  (xj).  All  from  Marsh. 

The  Turtles  (or  Chelonians  of  the  American  Cretaceous)  were  of  50  or 
more  species ;  and  one,  Protostega  gigas  of  Cope  (tAtlantochelys  Mortoni  Agas- 

1422. 


Fig.  1422,  Pteranodon  longiceps,  head  (x£) :  a,  upper  view  ;  6,  side  view.     Marsh. 

siz),  from  the  Niobrara  beds  of  western  Kansas,  had  a  head  two  feet  long, 
and  a  total  length  of  nearly  13  feet.     Desmatochelys  Lowii  of  Williston  is 
DANA'S  MANUAL  —  54 


850 


HISTORICAL  GEOLOGY. 


from  the  Benton  group  in  Kansas.  Species  of  Compsemys  occur  in  the 
Laramie  beds  at  Judith  River  and  elsewhere,  and  also  of  Trionyx  and  Plasto- 
menus.  Adocus  beatus  Leidy,  A.  punctatus  Marsh,  A.  agilis  Cope,  are  New 
Jersey  species. 


1423-1429. 


1424 


1423 


14-25 


BIRD.  —  Fig.  1423,  Hesperornis  recalls,  skeleton  (xj)  ;  1424,  left  lower  jaw,  top  view  (x$)  ;  1425,  same,  side  view ; 
1426,  tooth  (xf);  1427,  20th  dorsal  vertebra,  side  view  (xf);  1428,  same,  front  view;  1429,  pelvis  (x£>;  a, 
acetabulum  ;  il,  ilium  ;  is,  ischium  ;  p,  pubis  ;  p',  post-pubis.  Marsh. 


MESOZOIC    TIME  —  CRETACEOUS. 


851 


Pterosaurs  of  several  species  have  been  discovered  in  western  Kansas,  in 
the  "Middle  "  Cretaceous,  the  first  by  Marsh  in  1870;  two  had  an  expanse  of 
wings  of  20  to  25  feet,  and  another  of  18  feet.  They  are  toothless,  unlike  the- 
foreign  species,  and  are  named  by  Marsh  Pteranodonts ;  anodont  from  the 


1430,  1431. 


1430 


1431  a 


14316 


Bnu>.—  Fig.  1480,  Ichthyornis  victor,  skeleton,  restored  (xj);  1431  a,  6,  c,  d,  I.  dispar:  a,  left  lower  jaw,  side 
view  (xf)  ;  6,  same,  top  view  ;  c,  cervical  vertebra,  side  view  (xf)  ;  d,  same,  front  view.    Marsh. 


852  HISTORICAL   GEOLOGY. 

Greek,  signifying  tuithout  teeth.  The  skull  and  slender  bird-like  jaws  of 
Pteranodon  longiceps  Marsh  are  shown  in  Fig.  1422  b,  and  an  upper  view  in 
Fig.  1422  a.  The  fore  limbs  (wings)  are  enormous,  the  hind  limbs  very 
small.  These  animals,  as  Marsh  observes,  have  several  vertebrae  anchylosed 
to  act  as  a  sacrum  to  the  pectoral  arch  (like  the  sacrum  in  the  pelvic  arch), 
for  the  support  of  the  powerful  wings.  The  skull  alone  of  P.  ingens  of 
Marsh  is  about  four  feet  long,  and  that  of  P.  longiceps  over  three  feet.  The 
abundance  of  their  remains  in  the  Kansas  beds  appears  to  show  that  these 
great  bird-billed  Pterosaurs  frequented  the  borders  of  the  Cretaceous  sea  as 
its  Kingfishers. 

3.  Birds.  —  The  Cretaceous  Birds,  in  part,  had  teeth  (like  the  Jurassic  of 
Solenhofen),  as  first  reported  by  Marsh  from  Kansas  specimens.     One  of  the 
species,  the  Hesperornis  regalis  of  Marsh,  five  to  six  feet  in  height,  is  repre- 
sented in  Fig.  1423  (reduced  to  i)  from  an  essentially  complete  skeleton. 
The  figures  also  illustrate,  besides  the  skeleton,  one  of  the  teeth,  the  jaw  in 
two  positions,  a  dorsal  vertebra,  and  the  pelvis.     The  teeth  are  fixed  in  a 
groove,  as  in  many  Reptiles.     This  large  bird  had  short  wings,  ostrich-like, 
with  many  of  the  characteristics,  of  a  Loon,  one  of  the  Divers.     Another 
Kansas   bird  of  different  type  is  the  Ichthyornis  victor  of  Marsh,  a  small 
bird,  with  good  wings.     The  fish-like  feature  to  which  the  name  alludes  is 
the  biconcave  form  of  the  vertebrae.     But,  with  this  low-grade  feature,  it 
has  the  teeth  in  sockets.     In  the  restored  skeleton  (half  the  natural  size), 
Fig.  1430,  the  bones  actually  found  are  those  of  the  shaded  part.     Apatornis 
of  Marsh  is  a  related  bird.     Marsh  has  described,  also,  species  of  two  other 
genera  related  to  Hesperornis;  namely,  Baptornis  and  Coniornis,  the  latter 
from  the  Fox  Hills  group,  Montana.     All  the  Cretaceous  birds  have  the  fore 
limb  greatly  modified  for  wing  purposes,  bird-like ;  but  in  the  Hesperornis 
it  has  passed  beyond  this  and  become  rudimentary,  as  in  the  Ostrich.     This 
is  in  striking  contrast  with  the  earlier  Jurassic  birds,  in  which  the  fore  limb 
is  more  completely  and  normally  a  leg  than  a  wing.      The  toothless  birds 
(or  those  not  yet  proved  to  be  toothed)  of  the  Cretaceous  beds  of  New  Jersey 
were  related  to  the  Cormorants  and  Waders. 

4.  Mammals.  —  The  Mammals  of  the  Cretaceous  thus  far  discovered  are 
probably  all  Marsupial  or  Monotreme,  like  those  of  the   Jurassic  period. 
The  remains  are  mainly  teeth,  with  a  few  broken  jaws  and  limbs.     The 
earliest  described  is  the  Meniscoessus  conquistus  of  Cope,  discovered  by  J.  L. 
Wortman  in  the  Laramie  of  Dakota  (1882,  1884).     Many  kinds  have  been 
described  by  Marsh  (1889-1892).     The  following  figures  are  from  his  plates 
of  1892. 

The  figures  1432-1438  are  supposed  by  Marsh  to  represent  teeth  and  por- 
tions of  jaws  of  Marsupials,  and  the  remainder  probably  of  Monotremes. 
The  teeth  of  the  genus  Tripriodon  have  some  resemblance  to  the  tooth  of  the 
Meniscoessus  figured  by  Cope,  and  have  been  referred  by  Osborn  to  that 
species. 


MESOZOIC   TIME  —  CRETACEOUS. 


853 


1432-1443. 

b  c 


1432  a 


1438  a 


1434  a 


14346 


MONOTREME  AND  MAK8TJPIAL  MAMMALS.  —  Fig.  1432  a,  Cimolestes  incisus,  left  lower  jaw  (x  2) ;  1432  6,  c, 
lower  molar  (x  3)  ;  1432  d,  e,  id.,  canine,  natural  size  ;  1433  a,  6,  c,  Didelphops  comptus,  upper  molar  (x  3) ; 
1434  a,  D.  vorax,  two  upper  molars  (x  2)  ;  1434  6,  Didelphops,  milk  tooth  (x  3) ;  1435  a,  6,  D.  ferox,  views 
of  right  lower  jaw ;  1436  a,  Batodon  tenuis,  lower  jaw  (x  3)  ;  1436  6,  id.,  with  last  two  molars  (x  2)  ;  1436 
c,  d,  e,  id.,  upper  molar  (x  3)  ;  1437  a,  b.  c,  Stagodon  validus,  premolar  (x  2) ;  1437  d,  id.,  left  lower  canine ; 
1437  e,  id.,  part  of  lower  jaw,  sho%ving  canine  and  two  molars,  natural  size ;  1438  a,  6,  Stagodon  tumidus, 
upper  premolar  (x  2)  ;  1439  o,  6,  Oracodon  conulus,  upper  premolar  (x  3)  ;  1440,  Dipriodon  lunatus,  natural 
size ;  1441  a,  6,  Halodon  sculptus,  right  lower,  fourth  premolar  (x  2)  ;  1441  c,  id.,  left  lower  incisor ;  1442, 
Tripriodon  ccelatus,  right  upper  molar  (x  2)  ;  1443,  T.  caperatus,  right  upper  molar  Cx  2).  Marsh,  1892. 


854  HISTORICAL   GEOLOGY. 


Characteristic  Species. 

NEW  JERSEY.  — The  following  lists  of  New  Jersey  species  are  from  the  reports  of  R.  P. 
Whitfield,  from  whom  have  been  taken  also  the  chief  part  of  the  references  to  occurrence 
in  the  Ripley  group  of  Alabama  (indicated  by  R.),  and  in  the  Upper  Cretaceous  beds  ol 
Texas  (indicated  by  T.) ;  the  other  references  being  from  T.  W.  Stanton :  — 

Lower  Greensand.  —  Catopygus  pusillus,  Cassidulus  florealis,  Terebratula  Harlani, 
Terebratella  plicata,  Ostrea  larva  (R.,  T.),  Exogyra  costata  (R.,T.),  Gryphcea  vesicularis 
(R.,  T.),  Pecten  venustus,  Amusium  simplicum  (R.)?  Neithea  quinquecostata  (R.)i  Radula 
acutilineata  (R.)»  Spondylus  gregalis,  Germlliopsis  ensiformis  (R.,  T.),  Inoceramus  Crispii 
var.  Barabini  (R.,T.),  Idonearca  vulgaris  (R.,  T.),  Trigonia  Mortoni,  T.  Eufaulensis  (R.), 
Cardium  (Criocardium)  dumosum  (R.,  T.),  C.  Eufaulense  (R.,  T.),  Crassatella  vadosa 
(R.),  Veniella  Conradi  (R.,  T.),  F.  trapezoidea  (R.),  Anchura  abrupta  (R.,  T.),  Cypri- 
meria  depressa  (R.,  T.),  Gyrodes  crenatus  (R.,  T.),  G.  petrosus  (R.,  T.),  Veleda  lintea 
(R.,  T.),  Leptosolen  biplicata  (R.,  T.),  Scalaria  Sillimani,  8.  Hercules,  Turritella  com- 
pacta,  T.  vertebroides  (R.,  T.),  Ligumen planulatum  (R.,  T.),  Nautilus  Dekayi  (R.,  T.), 
Placenticeras  placenta  (R.,  T.),  Scaphites  hippocrepis,  S.  Conradi  (R.)»  Baculites 
ovatus  (R.,  T.),  B.  compressus,  Turrilites  pauper,  Solenoceras  annulifer,  Belemnitella 
Americana  ;  and  in  the  Clay  Marls,  below  the  Lower  Greensand,  Ammonites  (Mortoniceras} 
Delawarensis. 

Middle  Greensand.  —  Montlivaltia  Atlantica,  Cidaris  splendens,  Pseudodiadema 
diatretum,  Ananchytes  ovalis,  Hemiaster  parastatus,  Terebratula  Harlani,  Gryphcea 
vesicularis,  Gryphceostrea  vomer,  Natica  abyssina,  Isocardia  Conradi,  Nautilus  Dekayi, 
Baculites  ovatus,  Sphenodiscus  lenticularis. 

Base  of  Upper  Marl  bed.  —  Terebratulina  Atlantica,  Ostrea  glandiformis,  Gryphcea 
Bryani,  Crassatella  curta,  C.  littoralis,  Turritella pumila,  Rostellaria  noMlis,  Pleuroto- 
maria  Brittoni. 

The  latest  and  fullest  work  on  New  Jersey  Brachiopods,  Lamellibranchs,  Gastropods, 
and  Cephalopods,  with  illustrations  of  all  the  species,  is  Whitfield's  Report,  in  4to,  U.  8. 
G.  S.r  vol.  ix.,  1885,  and  vol.  xviii.,  1892.  It  contains  full  references  to  the  works  of 
Morton,  Lea,  Conrad,  and  all  other  authors  on  New  Jersey  Cretaceous  paleontology. 

MISSISSIPPI  AND  ALABAMA.  —  Eutaw  group, — chiefly  Oysters  in  the  marine  part. 
Rotten  Limestone :  Placuna  scabra,  Neithea  quinquecostata,  Gryphcea  convexa,  G.  vesicularis, 
G.  Pitcheri,  Ostrea  falcata,  Eudistes,  Mosasaurus ;  and  in  the  Tombigbee  sand,  many 
Selachian  remains,  and  the  gigantic  Ammonites  Mississippiensis  Spillm. 

Hipley  group. — Besides  the  species  indicated,  in  the  list  for  the  Lower  Greensand 
group,  by  the  letter  R.,  the  following  are  common  kinds;  the  references  to  Texas  are 
from  Whitfield  and  Stanton:  Ostrea  subspatulata  (T.),  Gryphcea  mutabilis,  Anomia 
argentina,  Inoceramus  proximus,  Germlliopsis  ensiformis,  Cucullcea  capax,  Pecten  quin- 
quecostatus,  Nucula percrassa  (T.),  Aphrodina  Tippana  (T.),  Veleda  lintea  (T.),  Lunatia 
obiquata  (T.),  Pugnellus  densatus  (T.),  Pyrifusus  subduratus  (T.),  Volutomorpha 
Eufaulensis  (T.),  Morea  naticella  (T.),  M.  cancellaria  (T.),  Cinulia  pulchella  (T.), 
Baculites  anceps  (T.). 

TEXAS.  —  (The  species  of  the  Upper  Cretaceous  are  wholly  different  from  those  of  the 
Lower.) 

(1)  Lower  Cross  Timbers:    Leaves  of  Salix,  Ilex,  Laurus,  etc.  (Shumard);  Otodus 
appendiculatus,  and  other  Fish  remains  ;  Anguillaria  Cumminsi  White,  species  of  Ostrea, 
Cerithium,  Turritella,  Neritina,  Scaphites,  with  Ammonites  Swallovi  Shumard. 

(2)  Eagle  Ford  shales :  Isastrcea  discoidea  White,  Ostrea  congesta  Con.,  0.  belliplicata, 
Exogyra  columbella  Meek,  Lima  crenulicosta  Roemer,  Inoceramus  labiatus,  I.  latus  Sow., 
/.  confertim-annulatus  Roemer ;  the  Ammonoids,  Buchiceras  Swallovi,  Hoplites  Deshayesi, 


MESOZOIC   TIME  —  CRETACEOUS.  855 

Acanthoceras  mammillare,  Scaphites  Texanus  R. ;  Ptychodus  mammillaris,  Lamna  com- 
pressa,  L.  Texana,  Gfaleocerdo,  Carcharodon. 

(3)  The  Austin  limestone  (chalk):  Rhizopods  of  the  genera  Textularia  and  Globigerina  ; 
also  Hemiaster  Texanus  R.,  Cassidulus  cequoreus  Morton,  Terebratulina  Guadalupce  R., 
Ostrea  congesta,  Gryphcea  vesicularis  Lamk.,  Exogyra  ponderosa  (young  form),  E.  costata 
Say,  E.  columbella,  Ostrea  larva,  Pecten  Nillsoni,  Inoceramus  biformis,  I.  umbonatus,  L 
subquadratus,  I.  exogyroides,  L  labiatus,  Eadiolites  (?)  Austinensis  R.,  Eulima  Texana  R., 
Chemnitzia    gloriosa  R.,    Nautilus    DeTcayi,   Baculites    anceps,   B.   asper,    Ammonites 
(Placenticeras)  Guadalupce  R.,  A.  (Mortoniceras)  Texanus  R.,  Mortoniceras  Shoshonense, 
Schlcenbachia  dentato-carinata  R. 

(4)  The    Taylor  or  Exogyra  ponderosa    marls:    E.  ponderosa   (very   abundant), 
Gryphcea  vesicularis,  Ostrea  larva,  Amusium  simplicum  Con.,  Pyrifusus  granosus  Con. 
The  species  have  greater  resemblance  to  those  of  the  Atlantic  and  Gulf  borders  than  to 
those  of  the  Continental  Interior ;  and  this  is  true  also  of  the  following. 

(6)  Glauconitic  beds  of  northeast  Texas :  the  species  of  (4),  and  also  Pecten  Burling- 
tonensis,  Inoceramus  Crispii,  Crassatella  lineata  Shum.,  Pachycardium  Spillmani, 
Pholadomya  Lincenumi,  Chemnitzia  gloriosa,  Purpura  cancellata,  Pleurotoma  Texana, 
P.  Tippana,  Anisomyon  Haydeni,  Nautilus  Dekayi,  Ptychoceras  Texanum,  Turrilites 
helicinus,  Helicoceras  Navarroense,  Baculites  annulatus,  B.  Spillmani,  B.  Tippoensis, 
Placenticeras  placenta,  Belemnitella  mucronata.  Further,  the  Eagle  Pass  beds  on  the  Rio 
Grande,  referred  to  the  age  of  the  Fox  Hills  and  Laramie,  contain  Ostrea  glabra  Meek, 
Anomia  micronema,  and  species  of  Area,  Cyrena,  Amm.  (Sphenodiscus)  pleurasepta  Con., 
and  other  species.  The  above  names  are  from  lists  by  Hill.  See  further,  for  species  of  the 
Glauconitic  group  and  Ponderosa  marls  that  are  identical  with  those  of  the  Ripley  and 
Lower  Greensand  groups,  tables  on  page  854. 

On  the  Invertebrate  Paleontology  of  Texas,  see  especially  F.  Rcemer,  Kreid.  Texas, 
1862;  also,  Pal.  Abhandl,  Berlin,  1888;  Shumard,  Acad.  Sc.,  St.  Louis,  i.,  1860,  and 
Boston  Soc.  N.  H.,  viii.,  1861-62;  R.  T.  Hill,  Am.  Jour.  Sc.,  1887;  Sep.  Geol.,  Texas, 
vol.  i.,  annotated  check-list,  Bull.  No.  4,  Geol.  Texas,  1889  ;  Proceedings  of  the  Biological 
Society  of  Washington,  D.C.,  vol.  viii.,  1893;  Bull.  Geol.  Soc.  of  Am.,  vol.  v.,  1894  ;  C.  A. 
White,  on  fossils  from  Texas,  Proc.  U.  S.  Nat.  Mus.,  ii.,  and  his  Correlation  of  the 
Cretaceous,  Bull.  U.  S.  G.  S.,  No.  82 ;  F.  W.  Cragin,  Texas  Geol.  Survey,  1893. 

CONTINENTAL  INTERIOR  (Upper  Missouri  region),  according  to  Meek :  — 

1.  DAKOTA  SERIES.  —  Besides  species  of  fossil  plants,  Pharella  (?)  Dakotensis,  Tri- 
gonarca  Siouxensis,  Cyrena  arenarea,  Margaritana  Nebrascensis,  etc. 

2.  COLORADO  SERIES.  —  (a)  Fort  Benton :  Inoceramus  labiatus,  I.  fragilis,  I.  tenui- 
costatus,   Ostrea  congesta,  Pholadomya  (Anatimya)  papyracea,   Scaphites  larvceformis, 
S.   vermiformis,   S.  ventricosus,   Nautilus    elegans ;    the   Ammonites,  A.  Mullananus, 
Mortoniceras  Shoshonense,  Prionocyclus  Woolgari,  etc.    (6)  Niobrara :  Inoceramus  (avicu- 
loides)  labiatus,  L  deformis,  Ostrea  congesta,  etc. 

3.  MONTANA  SERIES. — (a)  Fort  Pierre :  Inoceramus  sublcevis,  I.  Crispii,  I.tenuilineatus, 
Busycon  Bairdii,  Neithea  quinquecostata,  Anisomyon  borealis,  Lucina  occidentalis,  Avicula 
linguiformis ;  the  Aminonoids,  Ammonites  complexus  and  Placenticeras  placenta,  with 
Baculites  ovatus,  B.  compressus,  Helicoceras  Mortoni,  Scaphites  Conradi,  S.  nodosus; 
Nautilus  Dekayi.     (b)  Fox  Hills :  Anchura  Americana,  Pyrifusus  Newberryi,  Cardium 
speciosum,  Mactra  alta,  Tancredia  Americana,   Belemnitella  bulbosa,  Nautilus  Dekayi, 
Placenticeras  placenta,  Scaphites  Conradi,  Baculites  ovatus,  B.  grandis. 

No  species  of  the  genera  of  keeled  Ammonites,  Prionocyclus,  Prionotropis,  Morto- 
niceras, states  Stanton,  have  been  found  in  America  above  the  limits  of  the  Colorado 
formation ;  and  further,  no  species  of  Heteroceras,  Ptychoceras,  and  Anisomyon  occurs 
below  the  Montana,  no  large  Baculites,  such  as  B.  ovatus,  B.  grandis,  and  B.  compressus, 
nor  the  species  Scaphites  Conradi,  S.  nodosus. 


856  HISTORICAL   GEOLOGY. 

4.  LARAMIE  BEDS  at  Judith  Kiver  (Rep.  Hayden  Survey,  vol.  ix.,  4to),  according  to 
Meek,  in  the  lower  part :  Unio  Dance  and  U.  Deweyi,  Viviparus,  Goniobasis,  Sphcerium, 
Planorbis,  Ostrea  subtrigonalis  •  in  the  upper  part:  Ostrea  subtrigonalis  (?),  Corbicula 
occidentalis,  C.  cytheriformis,  Goniobasis  convexa,  etc. 

Among  Vertebrates  of  the  Laramie  beds  are  the  following :  At  Moreau  River,  South 
Dakota  (west  of  the  Missouri),  the  Plesiosaurids,  Plesiosaurus  occiduus  and  Ischyro- 
saurus  antiquus,  both  described  by  Leidy.  At  the  Judith  River  Basin,  remains  of  species 
related  to  the  Iguanodon  of  the  genera  Palceoscincus,  Troodon  and  Aublysodon  of  Leidy  ; 
according  to  Marsh,  of  Claosaurus,  of  Ceratopsids  and  Ornithomimus ;  of  Plesiosaurus 
and  lachyrosaurus ;  also  of  the  Rhynchoceph,  Champsosaurus  profundns  Cope ;  and 
Turtles  of  the  genus  Compsemys.  At  Black  Butte,  the  Ceratopsid,  Agathaumas  sylvestris 
Cope.  At  Castle  Gate  in  southwestern  Utah,  an  important  coal-mining  village,  a  species 
of  Claosaurus ;  in  the  Denver  group,  or  Upper  Laramie,  near  Denver,  species  of  Ceratops 
and  Ornithomimus.  Some  of  the  Mammals  of  the  Laramie  are  mentioned  on  pages  852, 
853. 

Aublysodon  mirandus  of  Leidy  (1859,  1868),  referred  by  him  to  the  tribe  of  Dinosaurs, 
was  based  on  a  number  of  teeth.  Marsh  has  suggested  (1892)  that  some  of  the  incisors 
figured  may  be  Mammalian,  stating  that  only  the  discovery  of  a  tooth  of  the  kind  in  a  jaw 
will  remove  doubt. 

Fossils  from  the  Cretaceous  formation  of  New  Jersey  were  first  described  by  the 
excellent  naturalist  of  Philadelphia,  Thomas  Say,  in  1820  (Am.  Jour.  Sc.,  ii.,  34),  who  then 
named  species  of  Baculites,  Exogyra  (instituting  this  genus),  and  Terebratula.  The  beds 
were  called  by  him  "the  New  Jersey  Alluvium."  The  first  reference  of  the  beds  to  the 
Cretaceous  formation,  and  first  account  of  their  geographical  distribution  along  the  Atlantic 
and  Gulf  borders,  was  made  by  Lardner  Vanuxem  in  January,  1828  (Acad.  N.  S.  Philad., 
vi.)  ;  and  the  first  systematic  description  of  the  fossils,  with  figures,  by  S.  G.  Morton, 
in  a  paper  of  the  same  date,  which  follows  Vanuxem's.  Vanuxem,  in  a  note  to  his  paper 
(page  63),  alludes  to  Morton's  extensive  collections  of  fossils  of  New  Jersey  and  Dela- 
ware, which  he  had  examined  in  addition  to  his  own.  Morton's  paper  was  soon  followed 
by  others  in  continuation. 

The  Radiolarians  found  by  Tyrrell  in  the  Montana  group,  Manitoba,  have  been 
described  and  figured  by  D.  Rust  (Canada  Survey,  1892). 

On  the  Invertebrate  paleontology  of  the  Continental  Interior,  see  especially  the  publi- 
cations of  Meek  in  connection  with  the  Hayden  Survey  and  also  elsewhere ;  also  papers 
by  C.  A.  White,  and  his  Correlation  of  the  Cretaceous  ;  also  T.  W.  Stanton's  Colorado 
Formation  (1893). 

FOREIGN. 
ROCKS  —  GENERAL  DISTRIBUTION. 

The  Cretaceous  formation  covers  a  large  part  of  southeastern  England, 
east  of  the  Jurassic  boundary,  from  Dorset  on  the  British  Channel  to 
Norfolk  on  the  German  Ocear  ;  and  also  a  narrow  coast  region,  about  and 
south  of  Flamborough  Head,  as  shown  on  the  map,  page  694,  and  small  areas 
in  northern  Ireland  and  on  the  islands  of  Mull  and  Morven,  off  Scotland, 
where  it  is  covered  by  Tertiary  basaltic  lavas. 

Like  the  Jurassic,  it  reappears  across  the  British  Channel  in  France  and 
Denmark,  and  to  the  east  and  south  over  much  of  Europe.  It  usually  out- 
crops along  the  borders  of  the  great  Tertiary  areas  or  within  them,  indicating 
that  the  seas  of  the  early  Tertiary,  which  cover  so  large  a  part  of  the  conti- 


MESOZOIC   TIME  —  CRETACEOUS.  857 

nent,  were  also,  for  the  most  part,  Cretaceous  seas  with  still  wider  limits 
and  larger  intercommunications.  The  London-Paris  basin,  spreading  east- 
ward to  Denmark,  was  one  of  these  partly  isolated  areas ;  it  was  800  miles 
wide  from  north  to  south  in  the  Cretaceous  period,  400  in  the  Jurassic,  and 
about  250  in  the  Tertiary.  Southwestern  France  and  the  northeastern  half 
of  Spain,  making  the  Pyrenean  basin,  was  another,  450  miles  broad ;  Switzer- 
land and  a  broad  area  across  Bavaria  was  another.  Italy  and  the  eastern 
coast  region  of  the  Adriatic,  with  a  very  broad  region  in  northern  Africa,  in 
Egypt  and  Syria  to  the  eastward,  made  another,  the  Mediterranean  basin. 
A  great  Austro- Russian  basin  spread  beyond  the  Azof  and  Black  seas  to  the 
Caspian,  the  Caucasus,  and  farther  east  over  large  areas  in  Persia;  and  in 
the  Neocomian,  it  is  supposed  to  have  extended  by  the  west  side  of  the 
Urals  to  the  borders  of  the  Arctic  Sea.  Only  parts  of  the  borders  of  these 
great  areas  are  at  surface  Cretaceous,  the  Tertiary  being  the  overlying 
formation. 

It  is  necessary  thus  to  view  the  Tertiary  with  the  Cretaceous  in  order  to 
appreciate  the  fact  that  Cretaceous  Europe,  across  from  the  Bay  of  Biscay 
and  Spain  to  its  eastern  border,  was  mostly  a  submerged  region.  The 
Mediterranean  basin,  like  that  of  the  West  India  and  Gulf  basin  in  America, 
was  the  deeper  part  of  the  submerged  area.  The  dry  land  included  the 
regions  of  Scandinavia  with  the  Baltic  provinces  in  Russia,  a  western  and 
northern  part  of  Great  Britain,  and  some  isolated  areas  along  the  western 
border  and  over  the  central  portions  of  the  continent.  The  resemblance  to 
North  American  distribution  consists  in  the  fact  that  the  dry  land  was 
most  extensive  to  the  north,  and  that  the  deepest  waters  were  about  the 
Mediterranean  Sea  on  the  south.  The  contrast  consists  in  the  widespread 
submergence  of  the  continental  surface  across  from  east  to  west,  and  the 
absence  of  any  distinctively  Atlantic  border  region. 

In  India,  there  is  no  evidence  of  marine  Cretaceous  beds  in  the  great 
valley  of  the  Ganges,  and  only  small  areas  near  Pondicherry  in  the  south- 
eastern part  of  the  Peninsula.  They  cover  a  large  area  in  Queensland,  north- 
eastern Australia,  and  occur  in  some  other  parts  of  that  continent.  They  are 
found  also  in  New  Zealand,  where  they  contain  valuable  coal-beds. 

In  South  America,  narrow  belts  of  Cretaceous  rocks  extend,  in  Venezuela, 
from  Cumana  to  Pamplona,  and  from  there  northward  and  southward  along 
the  Andes,  being  at  an  elevation  of  9000  to  14,000  feet  at  the  passes  of  the 
Portillo  and  Eio  Volcan,  and  having  a  height  of  20,000  feet.  The  Upper 
Cretaceous  forms  most  of  the  peaks  of  the  eastern  Andes,  some  of  the  ridges 
having  a  height  of  nearly  19,700  feet.  In  Peru,  latitude  111°  S.,  near  the 
pass  of  Antaranga,  its  height  is  about  15,750  feet,  and  in  the  Province  of 
Huamachuco,  the  Gault  reaches  a  height  of  16,405  feet.  In  Chile,  in  the 
Cordillera  of  Chilian  (36°  18'),  the  Cenomanian  has  a  height  of  nearly 
15,000  feet.  The  Cretaceous  are  the  oldest  of  the  beds  exposed  over  the 
most  of  northern  South  America,  the  crystalline  rocks  (Archaean)  excepted 
(H.  Karsten).  There  is  a  large  area  also  in  the  eastern  part  of  Brazil. 


858  HISTORICAL   GEOLOGY. 

C.  A.  White  has  described  Cretaceous  fossils,  from  the  provinces  of  Sergipe, 
Pernambuco,  Para,  Bahia,  and  elsewhere,  in  vol.  vii.  of  the  Archives  of  the 
National  Museum  of  Rio  de  Janeiro  (1888).  Darwin  found  Cretaceous  fossils 
in  Fuegia,  on  the  summit  of  Mount  Tarn  and  near  Port  Famine,  in  the 
Straits  of  Magellan;  and  the  author,  in  1838,  obtained  Belemnites,  probably 
Cretaceous,  on  the  shores  of  Orange  Bay,  near  Cape  Horn.1 

SUBDIVISIONS. 

In  view  of  the  very  wide  and  various  distribution  of  these  continental 
Cretaceous  beds,  and  the  diversity  of  conditions  as  to  water,  depth,  and  tem- 
perature under  which  they  have  originated,  it  is  not  to  be  expected  that 
there  should  be  uniformity  in  the  succession  of  rocks,  either  as  to  kinds  or 
as  to  fossils,  since  life  varies  in  distribution  with  variations  in  the  above 
conditions.  As  a  consequence,  the  Cretaceous  formation  is,  even  in  Europe, 
a  formation  with  or  without  chalk,  with  or  without  limestone,  with  or  with- 
out sandstones,  or  chiefly  made  up  of  sandstones,  and  with  wide  variations  in 
the  fauna. 

The  principal  British  subdivisions  are  the  following :  — 

I.  LOWER  CRETACEOUS.  — The  Neocomian  of  Thurman  (1832),  so  named 
from  the  Latin  name  of  Neufchatel,  Neocomium;  including  (1)  the  Wealden, 
and  (2)  the  Lower  Greensand,  but  restricted  by  some  to  the  Wealden. 

II.  UPPER  CRETACEOUS.  —  (1)  The  Gault  or  Albian,  consisting  of  clay 
with  some   greensand  (it   is   made   Lower  Cretaceous   by  most  European 
geologists) ;   (2)  the   Cenomanian,  consisting  of  (a)  the  Upper  Greensand, 
marl  beds,  and  the  Gray  Chalk  of  Folkestone ;  (3)  the  Turonian,  the  Lower 
White  Chalk  without  flints  ;   (4)   the  Senonian,  or  the  Upper  Chalk  with 
flints.     Above  comes,  in  Denmark,  (5)  the  Danian,  or  the  Maestricht  beds. 

The  Wealden,  including  the  Hastings  sands  below  and  the  Weald  clay 
above,  is  about  1500  feet  thick  in  southern  England,  where  it  was  deposited 
in  the  fresh  waters  of  a  delta  over  20,000  miles  in  area.  The  Gault  is  100 
feet  to  200  feet  thick.  The  chalk  without  flints  is  a  prominent  formation 
across  from  Flamborough  Head,  on  the  east  coast  of  England,  to  the  southern 
coast,  in  Dorset. 

The  "greensand"  is  like  that  of  America  (page  68).  The  chalk  con- 
sists chiefly  of  Foraminifers,  or  the  shells  of  Khizopods,  but  contains  also 
remains  of  Sponges  and  other  forms  of  life,  which  together  appear  to  indicate 
that  the  beds  were  formed  at  depths  of  a  few  hundred  feet  —  by  some  made 
300  fathoms  or  more;  they  are  similar  in  general  character  to  those  now 
accumulating  over  the  sea-bottom.  The  flint  nodules  occur  in  layers  in  the 
chalk.  The  facts  seem  to  show  that  the  sea-bottom,  on  account  of  depth  or 
for  some  other  reason,  was  in  a  more  favorable  condition  for  growing  siliceous 
Sponges  in  some  places  than  at  others.  The  material  of  a  flint  nodule,  while 

1  For  a  note  on  the  discovery,  see  Am.  Jour.  Sc.,  xxxv.,  83,  1888. 


MESOZOIC   TIME  —  CRETACEOUS.  859 

ordinarily  black  or  grayish-black  flint,  is  sometimes  chalcedony  or  agate,  and 
on  the  other  hand,  it  is  often  white  exteriorly  from  admixture  with  chalk. 
The  fantastic  shapes  of  some  flints  are  often  dne  in  part  to  the  fossils 
they  include. 

The  rocks  in  northern  France  or  Belgium  much  resemble  those  of  England. 
In  Germany,  above  the  Lower  Cretaceous,  there  is  a  large  predominance  of 
sandstones  and  marls.  In  Switzerland,  the  Lower  Cretaceous  of  the  Jura, 
about  Neufchatel,  is  mostly  limestone ;  and  of  the  same  nature  is  the  chief 
part  of  the  Upper  in  other  parts  of  Switzerland  and  the  Austrian  Alps.  The 
same  is  true  for  most  of  the  Cretaceous  of  Italy,  northern  Africa,  Syria,  the 
Mediterranean  region  being  marked  in  places  by  coral  reefs,  Hippurite  lime- 
stone, and  other  evidences  of  pure  ocean  waters. 

The  following  are  the  subdivisions  adopted  in  France  and  Belgium  and  Switzerland. 
(See  further  on  their  distinctions,  page  864.) 

2.  UPPER  CRETACEOUS. 

4.  DANIAN.  —  1.  Maestrichtian  or  Dordonian  ;  2.  Garumnian  (Pisolitic  limestone). 

3.  SENONIAN.  —  1.  Santonian  ;  2.  Campanian. 

2.  TURONIAN.  —  1.  Ligerian  ;  2.  Angouraian. 

1.  CENOMANIAN.  —  1.  Rhotomagian  ;  2.  Carentonian. 

1.   LOWER  CRETACEOUS. 

4.  ALBIAN  (=  Gault).  —  Vraconnian  =  Upper  Albian,  at  Cheville  in  the  Valais. 

3.  APTIAN  (=  rest  of  Lower  Greensand). 

2.  URGONIAN  (=  lower  part  of  Lower  Greensand).  —  1.  Urgonian  ;  2.  Rhodanian. 

1.  NEOCOMIAN  (=  Wealden).  —  1.  Valenginian  (=  Hastings  sand);  2.  Hauterivian 
(Weald  clay). 

LIFE. 

PLANTS.  —  The  plants  of  the  Wealden,  and  the  rest  of  the  Neocomian  in 
England  and  Europe,  are  Cycads,  Ferns,  and  Conifers,  as  in  the  Jurassic,  with 
a  show  of  progress  in  the  first  appearance  of  species  of  the  genera  Pinus  and 
AbieSj  the  true  Pines  and  Spruces,  but  with  no  Angiosperms.  But  in  the  Gault 
and  the  Upper  Cretaceous  occur  leaves  of  Angiosperms  of  many  common 
kinds,  though  all  of  extinct  species ;  as  the  Magnolia,  Myrtle,  Willow,  Wal- 
nut, Maple,  Fig,  Holly,  besides  a  Eedwood  (Sequoia) ;  and  there  were  also 
Palms,  of  the  genus  Palmacites.  No  remains  of  Lower  Cretaceous  Angio- 
sperms and  Palms  have  been  reported  from  England.  Vegetable  remains 
are  rare  fossils  because  the  beds  are  mostly  marine. 

The  microscopic  Protophytes,  called  Diatoms  and  Desmids,  are  found  in 
some  of  the  beds,  especially  in  the  flint.  The  Desmids  are  far  the  more 
common  because  not  siliceous,  and  therefore  not  dissolved ;  the  kinds  called 
Xanthidia  are  especially  abundant,  and  are  similar  to  those  from  Devonian 
hornstone  (page  583).  Coccoliths  are  common  in  the  Chalk. 


860 


HISTORICAL  GEOLOGY. 


1444 


ANIMALS.  —  1.  Rhizopods.  —  Foraminifers  are   commonly  the   principal 

material  of  the  Chalk.  Ac- 
cording to  Ehrenberg,  a  cubic 
inch  of  chalk  often  contains 
more  than  a  million  of  micro- 
scopic organisms,  which  are 
chiefly  the  shells  of  Rhizopods. 
Some  of  the  species  are  repre- 

RHIZoroDs.-Fig.  1444,  Lituola  nautiloidea  ;  1445, a,  Flabellina      S6nted    mUCli   enlarged   in  FigS. 
rugosa;    1446,   Chrysalidina   gradata;    1447,  a,   Cuneolina      1444-1447. 
pavonia. 

2.  Sponges.  —  Sponges  were 

of  like  importance  in  the  history  of  the  Cretaceous  rocks  on  account  of 
their  siliceous  spicules  and  framework,  which  were  the  chief  source  of  the 
flint.  The  recent  discovery  over  the  ocean's  bottom  of  Sponges  whose 
fibers  are  wholly  siliceous  was  a  revelation  as  to  their  importance  in 
flint-making.  The  species  are  mostly  of  the  Hexactinellid  and  Lithistid 


1448 


1448,  1449. 


1449  a 


14496 


SPONGE.  —  Fig.  1448,  Siphonia  lobata.    ECHINODERM.  —  Figs.  1449  a,  6,  Ananchytes  ovatus. 

kinds.  One  of  the  Lithistid  kind  is  represented  in  Fig.  1448,  and  spicules 
from  various  sponges  in  Figs.  446-460,  on  page  432,  obtained  by  G.  J. 
Hinde,  from  a  cavity  in  a  mass  of  flint,  which  afforded  also  a  multitude  of 
other  forms.  The  Cretaceous  Hexactinellids  comprised  the  goblet-shaped 
Ventriculites,  and  many  other  kinds. 

3.  Corals,  Echinoids.  —  Corals  and  Echinoids  were  common  in  some  of  the 
limestones,  especially  those  of  southern  Europe.     The  Corals  were  of  modern 
type  in  being  Hexacoralla ;  and  one  Cretaceous  genus,  CaryopkyUia,  has  still 
its  many  species. 

Echinoderms  were  of  many  genera  and  species,  especially  in  the  Upper 
Greensand  (Cenomanian)  and  chalk.  The  Ananchytes  ovatus,  Fig.  1449,  is  of 
the  Upper  Chalk  (Senonian)  of  England.  With  it,  and  also  in  the  Ceno- 
manian, occur  species  of  Holaster,  Micraster,  Salenia,  Galerites,  and  others. 

4.  Mollusks.  —  Lamellibranchs  included  many  species  of  the  genera  Gry- 
phcea,  Exogyra,  Inoceramus,  Trigonia,  which  are  rare  after  the  Cretaceous, 
or  end  with  it,  and  also  of  Pecten,  Lima,  etc.     They  comprise  also  the  pecul- 


MESOZOIC   TIME  —  CRETACEOUS. 


861 


iar  Rudistes,  of  which  there  are  over  a  hundred  species  in  the  Cretaceous, 
and  none  later;  they  are  especially  common  in  the  Mediterranean  region. 


1450-1455. 


1451 


1454 


LAMEI.LIBBANCHS,  Rudistes  Family.  —  Fig.  1450,  Hippurites  Toucasianus  ;  1451,  H.  dilatatus  ;  1452,  Kadiolitos 
Bournoni;  1453,  Sphaerulites  Hoeninghausi.    GASTROPODS.  —1454,  Nerinea  bisulcata  ;  1455,  Cinulia  avellana. 


Fig.   1450   represents   Hippurites    Toucasianus   d'Orb.   (with   a  small  one 
attached),  and  1451,  the  interior  of  the  shell  of  H.  dilatatus.     Figs.  1452, 

1453  show  the  forms  of  the  upper 

1456,  1457. 

1457 


1456 


valves,  in  profile,  of  species  of 
Eadiolites  and  Sphcerulites,  of  the 
same  family.  The  prominences 
b,  c  are  for  the  attachments  of 
muscles.  A  single  species,  Radio- 
lites  Mortoni  Woodw.,  has  been 
found  in  England.  Figs.  1454, 

1455,  are  Gastropods  of  the  pecul- 
iar  genera   Nerinea  and  Cinulia, 
both  now  extinct. 

Two  of  the  fresh-water  shells  from  the  Wealden  are  represented  in  Figs. 

1456,  1457,  one  a  Unio,  and  the  other  the  common  Viviparus. 
Ammonites  were  in  great  numbers ;  and,  as  in  America,  the  open-coiled 

forms  are  far  more  abundant  than  in  the  Jurassic.  Several  of  the  latter  are 
shown  in  Figs.  1458-1461,  and  a  spiral  form,  Turrilites,  in  1462.  Another 
related  form  is  that  of  the  open-coiled  Turrilite,  Helicoceras,  which  has 
several  species  in  Europe,  as  well  as  in  America.  Nautilus  also  has  many 


Fig.  1456,  Unio  Valdensis ;  145T,  Viviparus  (Paludina)  flu- 
viorum. 


862 


HISTORICAL  GEOLOGY. 


species.     The  Ammonites  Lewesiensis  Mant.,   from  the   Lower   Chalk   of 
England,  has  a  diameter  of  a  yard. 


1458 


1458-1462. 


1462 


CIPHALOPODS,    Ammonite   Family.  —  Fig.    1458,    Crioceras    Duvalii  ;    1459,    Ancyloceras    Matheronianum , 
1460,  Hamites  attenuatus;  1461,  Toxoceras  bituberculatum ;  1462,  Turrilites  catenatus. 

Vertebrates. — 1.  Fishes. — The  earliest  of  the  Teleost  Fishes  are  first 
known  from  remains  in  the  Middle  Cretaceous,  and  with  them  were  Sharks 
of  modern  as  well  as  ancient  type,  with  numerous  Ganoids.  Among  Teleosts, 
the  Salmon  family  was  represented  by  species  of  Osmeroides  (Fig.  1463), 

1463. 


TELEOST.  —  Osmeroides  Lewesiensis  (x 


8  to  14  inches  long  ;  the  Perch  family,  by  species  of  Beryx;  the  Herrings,  by 
species  of  Clupea;  Mackerels,  by  several  species;  the  rapacious  Saurodonts, 
by  species  of  the  American  genera  Saurorephalus,  Ichthyodectes,  Portheus, 


MESOZOIC   TIME  —  CRETACEOUS. 


863 


Daptinus,  etc.  Ganoids  were  numerous,  both  of  Cestraciont  Sharks  and  of 
Squalodonts,  the  latter  being  represented  by  species  of  the  genera  Carcharias, 
Lamna,  Oxyrhina,  Odontaspis,  Otodus,  etc. 

2.  Reptiles.  —  The  Wealden  of  England,  a  region  of  great  marshes  and 
lakes,  and  the  beginning  of  the  Cretaceous,  has  afforded  remains  of  30  or 
more  species  of  Dinosaurians,  Crocodilians,  and  Plesiosaurians.  The  number 
is  very  ]arge  even  for  an  area  of  20,000  square  miles  (100  miles  by  200).  But 
these  Reptiles  may  not  all  have  been  cotemporaries ;  yet  the  period  was 
not  so  long  but  that  one  of  the  Iguanodons  that  existed  in  the  Lower  Weal- 
den  continued  on  into  the  Lower  Greensand.  Moreover,  the  species  known 
may  not  be  a  fourth  of  those  that  existed  in  the  region  during  the  Wealden 
epoch.  They  included  Dinosaurs  of  nearly  all  the  subdivisions :  the  Her- 
bivorous Morosaurids,  as  Morosaurus  (Pelorosaurus)  BecJclesii,  Cetiosaurus 
brevis;  Stegosaurids,  as  Hylceosaurus  Oweni  and  Polacanthus  Foxi;  Ornitho- 
poda,  as  Iguanodon  Bernissartensis,  33  feet  long,  /.  Mantetti  20  feet  long, 

1465. 


1464. 


DINOSAUR.  —Fig.  1464,  Iguanodon  Bernissartensis  (x  £).    Dollo.     1466, 1.  Mantelli,  tooth,  natural  size.    Man  tell. 

Hypsilophodon  Foxi ;  Carnivorous  Dinosaurs,  as  Megalosaurus  Dunkeri. 
And  with  these  and  other  Dinosaurs,  there  were  some  Crocodilians,  a 
Plesiosaurus,  Chelonians,  and  several  species  of  Pterosaurs. 

The  skull  of  an  Iguanodon,  from  the  Wealden  of  Belgium,  is  represented 
in  Fig.  1464,  and  a  tooth,  full  size,  of  I.  Mantelli,  from  the  Wealden,  in  Fig. 
1465.  The  foot,  which  is  over  4|-  feet  long,  has  the  three-toed  characteristic 
of  the  Ornithopods.  The  genus  was  named  from  a  resemblance  in  the  teeth 
to  those  of  the  Iguana.  Among  the  Pterosaurs,  the  genus  Ornithostoma  of 
Seeley  includes  a  toothless  species  from  the  Cambridge  Greensand,  related  to 
Pteranodon  of  America. 

After  the  Wealden,  Reptiles  were  less  numerous.  But  both  Herbivorous 
and  Carnivorous  Dinosaurs  continued.  The  carnivorous  Acanthopkolis 


864  HISTORICAL   GEOLOGY. 

horridus  of  Huxley  occurs  in  the  Upper  Cretaceous,  and  Megalosaurus  Bredai 
of  Seeley  at  the  top  of  the  Cretaceous  in  the  Maestricht  beds.  Mosasaurids 
make  their  first  appearance  after  the  Neocomian,  as  in  America ;  a  Liodon 
occurring  in  the  Upper  Chalk,  and  Mosasaurus  Camperi  Meyer  (Fig.  1466), 
in  the  Maestricht  beds,  and  also  at  Lewes,  England. 

1466. 


Mosasaurus  Camperi  (x  ^). 

At  Gosau  in  the  northeastern  Alps,  Austria,  remains  of  the  horn-cores 
of  Ceratopsids  have  been  found  in  beds  of  the  Upper  G-reensand,  and  described 
under  the  name  Struthiosaurus. 

3.  Birds.  —  Imperfect  remains  of  two  species  of  Enaliornis  Seeley  have 
been  obtained  from  the  Cambridge  Greensand ;  and  Professor  Seeley  observes 
that  they  may  be  related  to  the  Hesperornis  of  Kansas.    A  species  of  Palceornis 
occurs  in  the  Wealden. 

4.  Mammals.  —  Only  one  species  had  been  reported  up  to  1894.     It  is 
referred  to  the  Jurassic  Marsupial  genus  Plagiaulax.     The  only  specimen 
is  a  molar  tooth  from  the  Wealden  of  Hastings  (S.  Woodward,  1891). 


Local  Subdivisions  and  their  Characteristic  Fossils. 
1.  LOWER  CRETACEOUS. 

A.  Great  Britain.  —  1.  The  WEALDEN.  (a)  The  Hastings  sand  and  clays,  or  Lower 
Neocomian,  which  have  afforded,  besides  plant  remains  and  fresh-water  shells,  the  bones 
of  many  Saurians. 

(&)  The  Weald  clay  or  Middle  Neocomian  (400'-1000'),  containing,  at  a  level  about 
100'  from  its  top,  the  Paludina  limestone,  sometimes  called  Sussex  marble,  consisting 
chiefly  of  fresh-water  shells  of  Paludina  flumorum  —  a  marble  "renowned  in  the  annals 
of  church  architecture."  In  addition  to  fresh- water  shells,  and  fish  remains,  there  are 
remains  also  of  Reptiles  ;  and  on  the  Isle  of  Wight  occur  Exogyra  sinuata  and  an  Ostrea. 

The  Lower  Greensand,  250'-450',  overlies  the  Wealden  in  southern  England,  but  over- 
laps northward  the  Upper  Oolytic  beds.  Contains  Ammonites  (Hoplites}  Deshayesi, 


MESOZOIC  TIME  —  CRETACEOUS.  865 

A.  (Hoplites)  Noricus,  Ancyloceras  gigas,  Diceras  Lonsdalei,  Exogyra  sinuata,  Gervillia 
anceps,  Pinna  Mulleti. 

The  clays  of  Speeton  cliffs  of  the  Neocomian  have  afforded  marine  fossils  ;  the  Lower, 
the  3  zones  of  Ammonites  (Olcostephanus)  Astierianus  (lowest),  with  Toxaster  complana- 
tus,  Olcostephanus  Speetonensis,  Hoplites  Noricus;  and  the  Middle,  Pecten  cinctus,  Exo- 
gyra sinuata,  Belemnites  jaculum,  etc. 

B.  France. — The  term  Neocomian,  as  first  used  (by  D'Orbigny)  was  restricted  to 
beds  of  the  age  of  the  Wealden  ;  his  Urgonian  (named  from  Orgon,  Bouches-du-Rhone), 
as  used  by  Lapparent  corresponds  to  the  lower  part  of  the  Lower  Greensand  (Atherton 
clay)  ;  Aptian,  to  the  rest  of  the  Lower  Greensand,  except  the  upper  part  (Folkestone 
beds)  ;  and  Albian,to  the  latter  with  the  Gault.  Lapparent  includes  all  to  the  top  of  the 
Gault  in  his  "  Infra-Cretace." 

The  Neocomian  is  divided  into  (1)  the  Valenginian  (so  named  from  the  Chateau  de 
Valengin,  near  Neufchatel),  and  (2)  the  Hauterivian  (so  named  from  Hauterive).  The 
Valenginian  contains  Toxaster  Campicheii,  Strombus  Sautieri,  Pygurus  rostratus,  Nerinea 
Favrei,  N.  Meriani ;  and  the  Hauterivian,  Dysaster  ovulum,  Toxaster  complanatus,  Ostrea 
Couloni,  0.  macroptera,  Pinna  Mulleti,  Trigonia  carinata,  Ammonites  (Hoplites)  radi- 
atus,  A.  (Engonoceras)  Gervillianus,  A.  (Olcostephanus')  Astierianus. 

The  Urgonian  contains  Heteraster  oblongus,  Requienia  ammonia,  E.  Lonsdalei, 
Radiolites  Neocomiensis.  The  upper  part  of  the  Urgonian,  containing  Heteraster  oblongus 
and  Requienia  oblonga,  is  the  Rhodanian  of  Renevier.  In  southern  France,  toward  the 
Pyrenees,  the  Urgonian  contains  Requienia  Lonsdalei  with  Orbitulina  conoidea,  0.  dis- 
coidea,  Nerinea  gigantea,  Heteraster  oblongus. 

The  Aptian  (from  Apt,  in  Vaucluse)  contains,  at  the  Perte-du-Rhone,  Epiaster  poly- 
gonus,  Plicatula  placunea,  Ostrea  aquila,  Trigonia  caudata. 

In  Germany,  the  Lower  Cretaceous  to  the  base  of  the  Gault  is  the  Hils  formation  or 
Neocomian.  In  northwestern  Germany,  in  Hanover,  on  the  borders  of  Holland,  the  Hastings 
sand  is  represented  by  the  Deistefsandstein,  containing  some  coal,  remains  of  Reptiles 
including  the  Iguanodon,  and  many  plants ;  and  above  this  is  the  Weald  clay  (Walder- 
thon)  70'-100'.  The  marine  beds  in  north  Germany  contain  Toxaster  complanatus, 
Ammonites  (Olcostephanus')  Astierianus,  Hoplites  radiatus,  Hoplites  Noricus,  Exogyra 
Couloni.  Next  is  the  Gault,  the  lower  part  of  which  is  made  the  equivalent  of  the  Lower 
Greensand  of  England,  or  the  Aptian,  with  Ammonites  Martini,  A.  Deshayesi,  Exogyra 
Couloni,  and  the  rest  the  English  Gault,  with  Ammonites  (Schlonbachia)  inftatus,  A. 
(Hoplites)  auritus,  A.  (Hoplites)  lautus,  A.  (Hoplites)  interruptus. 

2.   UPPER  CRETACEOUS. 

1.  Albian  or  Gault.  —  In  England  contains  Ammonites  (Hoplites)  auritus,  A.  (Schlon- 
bachia) varicosus,  A.  (Schlonbachia)  cristatus,  A.  (Acanthoceras)  mammillaris,  Inocera- 
mus  sulcatus,  Pterocera  bicarinata,  Hamites  attenuatus  (Fig.  1460),  Toxoceras  bitubercu- 
latum  (Fig.  1461),  Turrilites  catenatus.     Includes  3  zones  according  to  Barrois,  those  of 
(1)  Schlonbachia  inflata;   (2)  Hoplites  interruptus ;    (3)  Acanthoceras  mammillare.     In 
France,  near  Montierender,  there  are  the  Ammonites :  (I)  Schlonbachia  inflata  ;  (2)  Hop- 
lites splendens,  Hoplites  auritus,  Acanthoceras  mammillare,  Hoplites  Deluci,  Acanthoceras 
Lyelli;  (3)  Turrilites  catenatus.     The  Gault  is  the  Flammenmergel  of  Germany  with 
Schlonbachia  inflata,  Hoplites  lautus,  Hoplites  auritus,  Aucella  gryphceoides. 

2.  Cenomanian.  —  In  England  consists  of  (1)  the  Upper  Greensand,  (2)  Chloritic  or 
Glauconitic  Marl,  (3)  Chalk  Marl,  (4)  Gray  Chalk.     The  Upper  Greensand  contains  below, 
Exogyra  conica,  Pecten  quadricostatus,  Inoceramus  concentricus,    Cardium  Hillanum, 
Trigonia  scabricula,  Hamites  alternatus,  and  above,  Holaster  nodulosus,  Pecten  asper, 
Terebratula  biplicata,  Rhynchonella  compressa.     The  Chloritic  Marl  contains  Terebratula 

DANA'S  MANUAL  — 55 


866  HISTORICAL   GEOLOGY. 

biplicata,  Solarium  ornatum,  Plicatula  inflata,  Schlonbachia  varians.  The  Chalk  Marl 
•contains  Holaster  Icevis,  Rhynchonella  Martini,  Turrilites  costatus,  Inoceramus  striatus, 
Schlonbachia  varians.  The  Gray  Chalk,  which  is  the  upper  part  of  the  Cenomanian, 
•called  also  the  Lower  Chalk,  includes  in  England  the  zones :  (1)  of  Scaphites  cequalis  and 
Plocoscyphia  mceandrina ;  (2)  of  Ehynchonella  Martini;  (3)  of  Holaster  subglobosus ; 
(4)  of  Belemnitella  plena. 

In  France,  the  beds  in  the  valley  of  the  Seine,  called  the  "  Craie  glauconieuse  "  or 
Rhotomagian  of  M.  Coquand,  contain  Holaster  suborbicularis,  Cidaris  vesiculosa,  Am- 
monites (Acanthoceras*)  Rhotomagensis,  Acanthoceras  Mantelli,  Turrilites  costatus,  Pecten 
asper,  Inoceramus  striatus.  The  overlying  Carentonian  of  Renevier  is  the  zone  of  Ostrea 
biauriculata,  Belemnitella  plena,  Caprina  adversa. 

In  Germany,  the  Cenomanian  is  the  Lower  Planer,  affording  Pecten  asper,  Ostrea 
diluviana,  Catopygus  carinatus,  Schlonbachia  varians,  Acanthoceras  Rhotomagense, 
Acanthoceras  Mantelli,  Turrilites  costatus,  T.  tuberculatus.  Three  zones  are  recognized  : 

(1)  zone  of  Pecten  asper  and  Catopygus  carinatus ;  (2)  of  Schlonbachia  varians;  and 
(3)  of  Acanthoceras  Rhotomagense  and  Holaster  subglobosus. 

3.  Turonian,  or  the  Lower  White  Chalk  without  flints,  with  the  nodular  chalk  of  Dover 
at  the  top,  contains  Holaster  planus,  Ananchytes  ovatus,  Rhynchonella  Cuvieri,  R.  pli- 
catilis,    Ostrea    vesicularis,   Spondylus  spinosus,   Ammonites   (Pachydiscus)  peramplus, 
Hemiaster  Verneuili.  Scaphites  Geinitzi. 

In  England  the  zones  recognized  are:  (1)  of  Rhynchonella  Cuvieri;  (2)  of  Tere- 
bratulina  gracilis  ;  (3)  of  Holaster  planus. 

In  France,  (1)  the  Ligerian  (named  from  the  basin  of  the  Loire)  (the  Middle  Planer 
of  Germany)  is  the  zone  of  Exogyra  columba,  Inoceramus  labiatus,  Pinna  decussata ;  and 

(2)  the  Angoumian,  the  zone  of  Terebratula  gracilis,  Holaster  planus,  and  of  Radiolite 
and  Hippurite  limestone  in  the  eastern  Alps. 

4.  Senonian,  or  the  Chalk  with  flints  (named  from  a  locality  of  chalk  at  Sens). 
Contains  Ananchytes  ovatus,  Micraster  cor-bovis,  M.  cor-anguinum,  M.  glyphus,  Inoce- 
ramus labiatus,  Spondylus  spinosus,  Ostrea  vesicularis,  Belemnitella  quadrata,  B.  mucro- 
nata,  Scaphites  pulcherrimus.     (1)  The  Santonian  is  the  zone  of  Micraster  brevis,  M.  cor- 
anguinum,  and  Inoceramus  digitatus;  (2)  the  overlying  Campanian  is  the  zone  of  Ostrea 
vesicularis,  Belemnitella  mucronata,  B.  quadrata,  and  includes  the  Upper  Quadersandstein, 
the  Lemberg  chalk,  and  chalk  of  Meudon  and  of  Reims. 

5.  Danian.  —  The  Lower  Danian  or  Maestrichtian  or  Dordonian  is  the  zone  of 
Nautilus  Danicus,   Ostrea  decussata,   Belemnitella  mucronata,  Baculites  Faujasi;  the 
Upper  or  Garumnian  (named  from  Garonne),  that  of  Micraster  tercensis,  and  includes 
the  chalk  of  Faxe,  fresh-water  beds  in  Provence,  and  marine  and  brackish-water  beds  in 
the  Pyrenees,  100'  to  1000'  thick.     From  the  Danian  comes  the  Mosasaurus  Camperi 
(page  864). 

In  Provence,  southeast  France,  the  SENONIAN,  overlying  the  Angoumian,  or  limestones 
containing  Hippurites  Petrocorriensis,  etc.,  includes,  according  to  M.  Toucas  (1891)  :  — 

1.  The  SANTONIAN  (a)  with  Hippurites  giganteus,  Rhynchonella  Petrocorriensis,  Tri- 
gonia  limbata ;  (6)  with  Amm.  tricarinatus,  Hippurites  brevis,  Micraster  brevis;  (c)  Am- 
monites   Texanus,   Inoceramus  digitatus,   Cidaris  clavigera;   (d)  Ammonites   Texanus, 
Actinoceras  verum,  Hippurites  Corbaricus,  Cidaris  clavigera. 

2.  CAMPANIAN,  (a)  Hippurites  dilatatus,  H.  Toucasi,  H.  socialis,  Ostrea  vesicularis; 
(ft)  Hippurites  dilatatus,  H.  Jloridus,  Ostrea  Merceyi,  Schizaster  atavus ;  Upper,  (c)  Ci- 
daris cretosa,  Ostrea  Matheroni,  Lima  decussata;  (d)  Ammonites  Gallici,  Nerinea  bisul- 
cata,  Hippurites,  Hemiaster  Regulusanus. 

The  following  species  are  reported  from  different  continents  :  — 

Ostrea  larva,  North  America  ;  Europe  ;  India.     Gryphcea  vesicularis,  North  America  ; 


MESOZOIC    TIME  —  CRETACEOUS.  867 

Europe ;  southwest  Asia.  Exogyra  Icevigata  Sow. ,  Europe ;  Colombia,  South  America. 
Exogyra  Boussingaultii  D'Orb.,  Europe  ;  Colombia,  South  America.  Inoceramus  Crispii 
Mant.,  North  America;  Europe.  Inoceramus  latus  Mant.,  North  America;  Europe. 
Inoceramus  mytiloides  Mant. ,  North  America  ;  Europe.  Neithea  Mortoni,  North  Amer- 
ica ;  Europe  ;  India ;  Peru,  South  America.  Pecten  circularis  Goldf . ,  North  America ; 
Europe;  India;  Peru;  South  America.  Trigonia  limbata  D'Orb.,  North  America; 
Europe  ;  India.  Trigonia  aliformis  Sow.,  North  America  ;  Europe  ;  southwest  Asia ; 
Colombia,  South  America.  Trigonia  longa  Ag.,  Europe ;  Colombia,  South  America. 
Hippurites  organisans,  Europe ;  southwest  Asia ;  Peru  and  Chile,  South  America. 
Nerinea  bisulcata  D'Arch.,  North  America  (Texas) ;  Europe.  Baculites  anceps,  North 
America ;  Europe  ;  Chile,  South  America.  Ammonites  vespertinus  Mort.,  North  Amer- 
ica ;  Europe. 

In  South  America,  in  the  Argentine  Cordillera,  Behrendien  found  the  following 
European  Cretaceous  species:  Hoplites  dispar  D'Orb.,  H.  Desori  Pictet,  Lithodomus 
prcelongus  D'Orb.,  Corbula  Neocomiensis  D'Orb.,  Mytilus  simplex  and  M.  Carteroni 
D'Orb.,  Exogyra  subplicata  Roam.,  Astarte  obovata,  and  others  (1892).  Two  Cretaceous 
fossils  from  St.  Paul's  and  St.  Peter's,  islands  in  the  straits  of  Magellan,  have  been  described 
by  C.  A.  White  (Proc.U.  S.  Nat.  Mus.,  xiii.,  13,  1890),  namely  a  large  Ham ites,  probably 
H.  elatior  of  Forbes,  a  species  collected  by  Darwin,  and  a  large  Lucina. 

In  La  Plata,  in  South  America,  the  Cretaceous  (probably  Lower  Cretaceous)  has 
afforded,  according  to  Lydekker  (1893),  Dinosaurs,  of  new  genera,  two  of  the  Sauropod 
type,  Titanosaurus  and  Argyrosaurus,  and  one  Microccelus,  of  undetermined  relations. 

The  Cretaceous  of  Brazil  along  the  coast  region  between  3°  and  13°  S.  probably 
constitutes  the  Abrolhos  Islands,  and  is  found  also  in  the  interior  along  the  Puriis.  The 
Bahian  group  of  Hartt,  supposed  to  be  Neocomian,  has  afforded  Saurians  ;  the  Sergipian, 
Upper  or  Middle  Cretaceous,  contains  Ceratites  and  Ammonites,  some  identical  with 
species  of  the  Texas  Cretaceous.  The  Continguiban  group,  probably  Senonian,  as  in  the 
Province  of  Sergipe,  contains  Ammonites  and  Inocerami.  The  Amazonian  group  of 
Puriis  —  Upper  Chalk  or  Maestrichtian  —  has  afforded  remains  of  Mosasaurs  and  Turtles. 


GENERAL   OBSERVATIONS   ON  THE    CRETACEOUS   PERIOD. 

GEOLOGICAL  AND   GEOGRAPHICAL  PROGRESS. 

1.  General  progress.  —  Continental  progress  in  North  America  previous 
to  the  Cretaceous  period  was  chiefly  interior  work ;  the  work  of  the  great 
Interior  Continental  seas,  —  endogenous,  as  it  has  been  styled.  During  the 
Cretaceous  period,  this  endogenous  work  was  continued  over  the  Western 
Continental  Interior ;  but,  in  addition,  progress  went  forward  largely  through 
sea-border  work,  on  both  the  Atlantic  and  the  Pacific  sides.  On  the  Atlantic, 
after  marine  formations  began,  no  outside  ridges  or  elevated  land  are  sup- 
posed to  have  existed ;  and  this  appears  to  have  been  the  fact  also  on  parts 
of  the  Pacific  border. 

In  Europe,  the  rock-making  continued  to  be  essentially  Interior  Conti- 
nental throughout  the  period.  The  beds  of  Mull,  Morven,  and  Antrim  were 
deposited  within  one  of  the  continental  troughs ;  for  the  Archaean  Hebrides 
existed  outside,  and  probably  were  a  longer  range  than  now.  It  was  the 
same  sinking  trough,  moreover,  in  which  beds  had  been  deposited  during 
earlier  Mesozoic  times. 


868  HISTORICAL   GEOLOGY. 

2.  Changes  at  the  close  of  the  Lower  Cretaceous.  —  After  the  earlier 
Cretaceous,  the  emergence  of  the  Mexican  plateau  took  place,  shutting  off 
the  Atlantic  waters  from  the  Pacific;  and  at  the  same  time,  movement 
change  occurred  in  Texas.  According  to  Hill,  faults  and  flexures  were 
produced,  especially  in  the  vicinity  of  Austin.  The  general  direction  of 
the  faults  in  the  region  is  N.  20°  E.  The  amount  of  displacement  is  gen- 
erally less  than  100  feet ;  but  in  the  chief  fault  it  is  500  to  750  feet,  and 
the  course  is  marked  by  an  escarpment  100  to  250  feet  high.  Along  the 
faults  the  beds  are  in  some  places  flexed,  and  the  limestone  is  rendered 
crystalline.  Moreover,  there  is  an  abrupt  transition  in  species  in  passing 
from  the  Lower  to  the  Upper  Cretaceous.  The  Potomac  beds,  of  the 
Atlantic  border,  underwent  some  change  in  level  and  some  surface  erosion ; 
but  no  upturning. 

On  the  California  coast  the  continuity  of  the  Shasta-Chico  series  indicates 
that  the  general  subsidence  mentioned  by  Diller  as  in  progress  during  the 
Cretaceous  period  was  not  interrupted  at  the  close  of  the  Lower  Cretaceous. 
But  in  Western  British  America,  the  increased  subsidence  which  introduced 
the  Upper  Cretaceous,  and  spread  the  sea  over  the  Continental  Interior,  is 
supposed  by  G-.  M.  Dawson  (1890)  to  be  marked  in  a  deposit  of  marine 
conglomerates,  occurring  in  many  places  in  the  southern  part  of  British 
Columbia,  in  the  Queen  Charlotte  Islands,  northward  about  the  Upper 
Yukon,  and  eastward  along  the  line  of  the  Eocky  Mountains.  Dawson 
reports  also  that  at  this  stage  of  the  Cretaceous,  or  near  it,  there  was 
renewed  volcanic  activity  in  the  Queen  Charlotte  Islands  and  in  the  Kocky 
Mountain  Range. 

BIOLOGICAL  CHANGES  AND  PROGRESS. 

Part  of  the  biological  history  of  Mesozoic  time  has  already  been  reviewed. 
Still  greater  changes  took  place  in  this  later  portion,  and  these  now  come 
under  consideration. 

Plants:  Cycads,  Angiosperms,  Palms.  —  The  Cycads,  the  most  charac- 
teristic feature  of  the  Trias  sic  and  Jurassic,  had  their  maximum  develop- 
ment during  the  latter  period.  They  were  still  prominent,  however,  in  the 
forests  of  the  Early  Cretaceous,  and  flourished  even  in  the  Arctic  regions 
on  Greenland,  Spitzbergen,  and  Alaska;  but  they  were  subordinate  to  the 
Conifers,  and,  in  the  Upper  Cretaceous,  to  the  Angiosperms.  At  present 
there  are  only  about  50  species  of  Cycads. 

The  line  leading  up  to  Angiosperms  is  uncertain.  It  is  a  notable  fact 
that  remains  of  plants  of  this  class  are  wholly  absent  from  the  Wealden  of 
England  and  from  the  Kootanie  of  America,  and  that  only  one  species  of 
doubted  locality  has  been  reported  from  the  Neocomian  of  Europe.  The 
75  species  identified  by  Fontaine  from  the  fossil  leaves  of  the  Potomac 
formation  of  eastern  America  show  that  the  trees  were  then  well  established 
in  the  American  forests,  although  Conifers  were  by  far  the  more  numerous. 
But  still,  as  Fontaine  shows,  they  leave  their  origin  unexplained. 


MESOZOIC    TIME  —  CRETACEOUS.  869 

The  Palms  came  in  during  the  Middle  Cretaceous  as  the  decline  of  the 
Cycads  made  progress.  It  is  supposed  probable  that  they  were  in  the 
successional  line  of  some  type  of  Cycads,  since  they  approach  them  in  their 
foliage,  in  their  usually  simple  stems,  and  in  having  the  pithy  interior 
traversed  by  bundles  of  woody  fibers. 

Progress  in  Mollusks :  Culminations  under  the  type.  —  The  Tetrabranch 
Mollusks,  which  include  the  Nautilus  and  Ammonite  tribes,  pass  their  climax 
and  decline  in  the  Cretaceous  period.  The  Nautiloid,  which  commenced 
with  a  straight  body  and  a  shell  no  longer  than  the  little  finger,  and  was 
continued  in  curved  and  coiled  forms,  and  reached  its  maximum  in  the 
Carboniferous,  is  continued  to  the  present  time,  but  only  in  two  or  three 
species  of  Nautilus ;  and  these  are  the  last  of  the  Tetrabranchiates.  The 
Ammonite  section,  which  commenced  with  the  closely  coiled  Goniatite  in 
the  Early  Devonian,  became  increasingly  complex  in  the  flexures  of  the 
septa,  and  finally  two  to  three  feet  in  diameter  in  the  Jurassic  and  Cretaceous 
seas,  where  it  numbered  thousands  of  species.  It  disappeared  entirely,  or 
nearly  so,  at  the  close  of  the  Cretaceous. 

The  Dibranchiate  Mollusks,  or  the  Cuttle-fishes,  whose  shells  are  internal 
when  any  exist,  are  known  first  from  the  later  Triassic  beds.  Under  the 
Belemnite  family  they  become  very  numerous  in  the  Cretaceous,  and 
apparently  end  at  its  close.  But  other  Cuttle-fishes  were  continued;  and 
probably  the  giant  species  of  modern  Newfoundland  and  other  seas,  having 
bodies  12  to  15  feet  long,  arms  of  25  feet,  and  eyes  of  8  inches  diameter,  the 
largest  in  the  animal  kingdom,  are  evidence  that  the  type,  and  the  type  of 
MolluskSj  has  now  its  time  of  culmination  as  to  grade  of  species,  though 
not  as  to  numbers  and  predominance  in  the  marine  fauna  of  the  world. 

Fishes:  their  culmination  in  Mesozoic  time.  —  The  type  of  Fishes  is 
supposed  to  have  culminated  as  early  as  the  Triassic  in  the  Ceratodus  and 
related  Dipnoans,  which  have  rudimentary  arms  in  the  fins,  essentially 
lungs  as  well  as  gills,  and  other  Amphibian-like  characteristics.  The  line  to 
the  Teleosts,  through  the  Amioids,  was  a  declining  line.  In  some  respects 
the  Teleosts  are  more  highly  specialized,  but  not  in  a  way  toward  superiority ; 
they  are  purer  representatives  of  the  Fish-type,  and  better  illustrate  the  fact 
that  the  Fish-type  is  a  low  style  of  Vertebrate.  The  Selachians  hold  to 
their  early  characteristics  of  a  cartilaginous  or  semiosseous  skeleton,  of  gills 
without  gill-covers,  and  of  a  heterocercal  or  vertebrated  tail.  The  Cestraciont 
Sharks,  which  were  common  in  the  Cretaceous,  became  fewer  afterward,  and 
now  only  four  species  exist  —  and  these  live  in  Australian  and  Japan  seas. 
The  Squalodonts,  or  Sharks  of  modern  type,  reached  later  their  time  of 
maximum  display. 

Decline  in  Amphibians.  —  Amphibians,  so  far  as  registry  gives  evidence, 
were  few  in  species  after  the  Triassic  period.  In  the  scale-covered  and  large- 
toothed  Labyrinthodonts  of  the  Permian  or  Triassic  periods  they  passed  their 
maximum  as  to  size,  grade,  and  numbers.  No  American,  British,  or  Euro- 


870  HISTORICAL   GEOLOGY. 

pean  species  of  Cretaceous  Labyrinthodonts  are  yet  reported.  The  species 
were  too  few  and  too  largely  terrestrial  to  have  secured  frequent  fossiliza- 
tion. 

Reptiles.  —  The  Reptiles  of  the  Cretaceous  are  for  the  most  part  a  con- 
tinuation of  Jurassic  types,  without  marked  evidence  of  upward  progress. 
The  Horned  Dinosaurs,  or  Ceratopsids  of  Marsh,  probably  the  latest  of  the 
larger  species,  while  showing  striking  advances  toward  Mammalian  forms 
in  the  bovine  or  rhinoceros-like  horns  and  the  two-pronged  teeth,  are  a 
degenerate  group,  specialized  downward,  not  upward.  As  Marsh  states, 
they  have  the  largest  heads  and  smallest  brains  of  any  of  the  Reptile 
race. 

The  Mosasaurids  also,  exclusively  Cretaceous  species,  illustrate  profound 
degeneration.  For,  in  these  Snake-like  species,  the  Lacertian  type  becomes 
enormously  multiplicate  posteriorly  in  the  vertebral  column;  the  legs  are 
reduced  to  fins,  as  in  Plesiosauriaus,  the  posterior  part  of  the  body  is  turned 
into  a  fish-like  skulling  organ,  and  made  the  chief  means  of  locomotion ;  and 
the  pelvic  girdle  has  lost  connection  with  the  vertebrae,  there  being  no  sacrum. 
Here  degeneration  has  developed,  not  imperfect  limbs  and  a  defective  skele- 
ton, not  something  between  a  Fish  or  Amphibian  and  a  Reptile,  but  a  pro- 
foundly decephalized  Reptile,  adapted  to  aquatic  life  as  if  its  outcome.  The 
last  of  the  Mosasaurs  in  America  occur  in  the  Montana  Cretaceous ;  in  Europe, 
in  the  beds  of  Maestricht. 

Snakes  are  known  from  the  American  Laramie,  and  also  from  the 
Cretaceous  of  France.  They  were  no  doubt  successors  to  an  aquatic  type, 
and  related,  it  is  supposed,  either  to  the  Mosasaurs,  or  to  the  Dolichosaurs  of 
the  English  Chalk. 

The  true  Crocodilians  have  a  heart  of  four  cavities,  and  traces  of  a 
diaphragm ;  and  the  teeth  are  implanted  in  sockets.  But  these  high  charac- 
teristics lose  part  of  their  apparent  significance  in  view  of  the  fact  (1)  that 
the  four-cavity  heart,  after  all,  does  not  prevent  the  commingling  of  the 
venous  and  arterial  blood  before  it  enters  the  system ;  (2)  that  the  character 
of  teeth  in  sockets  began  in  the  Permian ;  and  (3)  that  the  animal  has  limbs 
so  short  that  it  "drags  its  body  somewhat  along  the  ground/'  in  true 
Reptilian  style. 

The  Dinosaurs,  on  the  contrary,  stood  on  long  limbs  like  a  Mammal,  and 
had  nearly  the  same  freedom  of  locomotion.  They  were,  however,  as  has 
been  explained,  merosthenic  Reptiles,  that  is  Reptiles  having  great  and 
powerful  hind  limbs  as  the  chief  organs  of  locomotion,  with  usually  small 
fore  limbs  and  small  brains.  If  they  were  the  highest  of  Reptiles,  then  the 
Reptilian  type  reached  its  perfection  under  a  merosthenic  structure. 

But  the  distinction  of  highest,  as  remarked  on  page  797,  probably  belongs 
to  the  Pterosaurs,  which  are  eminently  prosthenic.  The  largest  species  of 
the  group  existed  in  the  Cretaceous  period.  It  is  not  improbable  that 
they  had  a  double  heart,  like  the  Crocodiles,  and  one  as  good  as  that  of  the 
Birds. 


MESOZOIC   TIME  —  CRETACEOUS.  871 

There  are  grounds  enough,  therefore,  for  the  conclusion  that  the  class  of 
Reptiles  culminated  in  the  latter  half  of  the  Reptilian  age.  The  reality  of 
the  Reptilian  feature  of  the  era  comes  out  strongly  on  comparing  the  great 
Reptiles  in  the  Wealden  as  to  size  and  numbers  with  those  of  the  present 
time. 

Now,  in  India,  or  the  continent  of  Asia,  there  are  but  two  species  of 
Reptiles  over  15  feet  long ;  in  Africa,  but  one ;  in  all  America,  but  three ; 
and  not  more  than  six  in  the  whole  world ;  and  the  length  of  the  largest 
does  not  exceed  25  feet.  During  the  Wealden  there  lived  in  England  alone 
16  large  Dinosaurs  and  12  Crocodiles,  besides  a  Plesiosaur  and  three  Ptero- 
saurs. The  Reign  of  Reptiles  becomes  more  strongly  pronounced  when 
the  little  Marsupial  Mammals  of  the  era  are  brought  into  view  by  way  of 
contrast. 

Birds.  —  Since  Birds  are  so  poorly  represented  among  fossils,  little  can 
be  said  as  to  progress  in  the  Cretaceous  period  beyond  the  fact  that  part  of 
the  Cretaceous  Birds,  as  known  first  from  Marsh's  discoveries,  retained  the 
teeth  of  the  Jurassic  Birds ;  and  some,  even  the  low  character  of  biconcave 
vertebrae.  They  had  lost  the  Reptile-like  bones  and  fingers  of  the  fore  limb, 
and  the  long  tail  existing  in  the  Jurassic  species,  and  had,  in  general,  the 
style  of  vertebrae  characterizing  modern  Birds,  besides  modern  features  in 
most  other  respects. 

It  is  also  a  fact  of  interest  that  already  degenerate  forms  were  in  exist- 
ence under  the  Bird-type ;  for  such  is  the  Hesperornis,  as  shown  in  its 
obsolescent  wing-bones  and  wings,  a  feature  that  reduced  it  to  the  meros- 
thenic  condition  of  an  Ostrich  and  a  Dinosaur.  Thus,  between  the  Middle 
Jurassic  and  Middle  Cretaceous  the  Bird-type  reached  essential  perfection, 
though  not  advanced  to  its  highest  stage ;  and  also  it  passed  along  at  least 
one  line  downward  to  Ostrich-like  imperfection.  The  presence  of  teeth  is 
not  a  structural  imperfection.  Their  absence  looks  much  more  so ;  but  it 
is  not  inconsistent  with  a  high  and  advancing  grade  of  structure  in  all  other 
respects. 

Progress  in  Mammals.  —  The  Monotremes  and  Marsupials  from  the  Creta- 
ceous formation  show  little  progress  in  Mammals  beyond  the  condition  in  the 
Jurassic  period  —  nothing,  up  to  the  present  time,  that  bears  the  decided 
character  of  a  placental  Mammal.  As  the  known  fossils  are  mainly  teeth 
and  jaws,  full  comparisons  are  not  yet  possible,  and  certainty  of  conclusion 
as  to  the  question,  Marsupial  or  not,  is  not  yet,  in  all  cases,  possible. 

Contrast  of  the  European  and  North  American  marine  faunas.  —  The 
contrast  between  the  marine  species  of  Europe  and  North  America,  which 
characterizes  the  Early  and  Middle  Mesozoic  (page  792),  continues,  but  in 
diminished  degree,  into  the  Cretaceous  period.  The  following  table  gives: 
the  number  of  species  that  have  been  described  from  the  Cretaceous  beds  of 
Great  Britain  and  North  America,  under  the  tribes  mentioned  in  the  first 
column;  the  former  from  Etheridge,  as  enumerated  by  him  in  1885;  the 
latter,  by  Whitfield,  in  1894. 


872  HISTORICAL  GEOLOGY. 

Great  Britain,  1885,     American,  1894, 
Etheridge  K.  P.Whitfleld 

Corals 76  27 

Echinoderms 201  65 

Brachiopods 106  28 

Lamellibranchs 476  1329 

Gastropods 298  839 

Ammonoids 206  224 

Nautiloids 20  12 

Belemnites 14  19 

Crustaceans 110  17 

The  contrast  is  equally  great  with  the  marine  fauna  of  the  Parisian  and 
Mediterranean  basins  in  Europe.  It  will  be  noted  that  the  American 
species  are  from  all  North  America.  The  species  are,  it  is  true,  but  imper- 
fectly studied ;  yet  the  contrast,  if  all  were  known,  would  be  strong.  Great 
Britain  leads  in  species  of  clear  seas,  and  those  of  moderately  deep  water  — 
Corals,  Echinoderms,  and  Brachiopods ;  and  if  the  comparison  were  confined 
to  the  Atlantic  border  of  North  America,  immensely  so  in  Ammonoids  and 
Nautiloids.  The  number  of  both  groups  from  this  border  is  only  24,  and 
that  of  Echinoderms  less  than  15. 

But  in  number  of  species  of  Reptiles  America  is  far  ahead  of  Britain  and 
Europe  ;  and  probably  because  its  broad  Western  Interior  had  a  vast  extent 
of  shallow  sea-borders  and  emerging  lands,  and  thus  afforded  them  especially 
favorable  conditions  for  existence. 


CLIMATE. 

During  the  Cretaceous  period,  a  warm  climate  still  prevailed  over  the 
earth  even  to  the  poles,  but  with  some  cooling  during  the  closing  part  of 
the  period ;  and  in  North  America  with  a  great  Central  Interior  Sea,  to  the 
end  of  the  period,  the  climate  was  moist.  The  Cycads  and  associated  species 
of  plants  in  the  lower  Cretaceous  beds  of  Greenland  indicate,  according  to 
Heer,  a  mean  temperate  of  21°  C.  to  22°  C.,  or  about  70°  F.  to  72°  F.  This 
temperature  is  that  of  Cuba.  The  facts  prove  that  a  somewhat  similar  tem- 
perature prevailed  at  the  same  time  over  Spitzbergen  and  in  Alaska,  where 
the  same  flora  existed ;  even  along  the  Atlantic  border  at  least  as  far  north  as 
Long  Island ;  in  the  region  of  the  Kootanie  beds  in  Montana  and  the  neigh- 
boring part  of  British  America ;  and  over  more  western  North  America 
to  Alaska.  The  Gulf  Stream  of  the  Atlantic  may  account  in  part  for  the 
extension  of  so  high  a  temperature  to  Greenland;  and  a  like  stream  over 
the  Pacific,  for  that  to  Alaska. 

The  plants  of  the  Vancouver  coal-beds,  and  those  of  the  Patoot  beds  in 
Greenland,  which  Dawson  refers  to  the  age  of  the  Montana  series,  he  com- 
pares with  those  of  Georgia  at  the  present  time,  where  the  mean  tempera- 
ture, he  states,  is  about  65°  E.  The  Dakota  plants  of  Kansas  and  elsewhere, 
with  those  of  the  Mill  Creek  group,  Canada,  and  the  Atane  of  Greenland, 


MESOZOIC   TIME  —  CRETACEOUS.  873 

are  intermediate  in  kinds,  some  Cycads  being  present  in  Greenland  as  well  as 
Kansas,  and  evidently  indicate  an  intermediate  temperature.  The  flora  of 
the  Laramie,  without  Cycads,  is,  according  to  the  same  authority,  "not  a 
tropical,  but  a  temperate  flora." 

The  testimony  as  to  temperature  from  the  animal  life  of  the  Cretaceous 
seas  bears  in  the  same  direction  with  that  from  plants.  There  appear  to 
have  been  no  true  coral  reefs  in  the  British  seas;  but  they  were  present 
beyond  doubt  in  the  Mediterranean  basin.  The  facts  lead  to  the  inference 
that  the  temperature  of  the  waters  about  the  British  Islands  was  below  a 
mean  of  68°  during  the  coldest  winter  month,  but  not  much  below,  while 
a  large  part  of  southern  Europe  was  within  the  Coral-sea  limit.  Texas 
was  in  all  probability  included  by  the  same  temperature  boundary, 
although  no  true  coral  reefs  and  not  many  species  of  Corals  have  yet  been 
reported  from  the  region. 

The  distribution  of  a  like  fauna,  for  the  most  part,  in  the  Lower  Green- 
sand  group  of  New  Jersey,  the  Eipley  group  of  the  Gulf  border,  and  the 
Montana  division  of  the  Cretaceous  of  Texas  and  the  Western  Continental 
Interior  testifies  to  a  nearly  common  temperature  in  the  waters  through  this 
long  geographical  range.  But  it  cannot  be  inferred  that  in  the  earlier 
Colorado  epoch,  or  the  later  Laramie,  the  temperature  was  alike  in  the 
waters  on  the  Atlantic  border  and  in  those  of  Texas  or  of  the  Interior  Con- 
tinental sea ;  for  the  influencing  conditions  were  widely  different ;  and  hence, 
even  if  there  were  a  full  series  of  fossils,  there  would  be  marked  differences 
in  the  cotemporaneous  beds  of  the  Interior  and  the  Atlantic  border.  The 
Texas  waters  were  within  the  subtorrid  influences  of  the  Mexican  Gulf,  with 
no  probable  source  of  cold  in  Arctic  currents.  But  on  the  Atlantic  border 
the  Labrador  current  may  have  much  modified  the  temperature  of  the 
waters,  even  if  partly  shut  off  by  the  closing  of  the  Straits  of  Belle  Isle. 
The  coast  had,  apparently,  no  Cape  Hatteras,  and  the  waters  of  the  Gulf, 
therefore,  had  free  sweep  from  the  tropics  to  Cape  Cod;  and  this  would 
have  reduced  the  effect  of  any  Arctic  flow  to  a  minimum. 

GONDWANA  LAND. 

The  belt  of  emerged  land  between  India  and  South  Africa,  mentioned  on 
page  737,  is  supposed  to  have  continued  to  exist  through  the  Jurassic  and 
Cretaceous  periods.  K.  D.  Oldham  remarks,  in  his  paper  of  1894,  speaking 
of  the  contrasts  of  the  fauna  of  eastern  and  western  India,  that  in  western 
India  the  Jurassic  fossils  belong  to  a  fauna  that  is  represented  in  the  north 
of  Madagascar,  in  northern  and  eastern  Africa,  and  also  in  Europe,  differ- 
ing so  completely  from  the  fauna  of  eastern  India,  that  "only  a  few 
species  of  world-wide  range  are  found  in  both."  Further,  the  remains 
of  plants  in  the  Jurassic  Rajmahal  series  of  the  east  coast  of  India  are 
mostly  identical  with,  or  closely  allied  to,  the  species  of  the  Uitenhage 
series  occurring  near  the  coast  of  South  Africa,  and  now  regarded  as 


874  HISTORICAL  GEOLOGY. 

Neocomian  or  Lower  Cretaceous ;  besides,  at  least  one  species  of  shell! 
occurs  in  both  regions.  It  is  thus  shown  that  the  belt  still  existed  during 
the  early  Cretaceous,  and  that,  at  the  same  time,  as  he  observes,  some 
barrier  along  the  region  separated  in  India  an  eastern  zoological  province 
from  a  western.  With  reference  to  the  connection  of  South  Africa  with 
Australia,  all  known  facts  would  be  explained  if  it  were  confined  to  the- 
Permian  and  early  Triassic  periods. 


POST-MESOZOIC   REVOLUTION:    MOUNTAIN-MAKING  AND  ITS, 

RESULTS. 

The  upturning.  —  The  close  of  Mesozoic  time  was  marked  by  the  making 
of  the  greatest  of  North  American  mountain  systems.  The  upturnings  took 
place  along  the  summit  region  of  the  Rocky  Mountains,  where  over  a  broadi 
belt,  as  long  probably  as  the  western  side  of  the  continent,  a  series  of 
geosynclines  had  been  accumulating  deposits  ever  since  Archaean  time. 
This  mountain  system  of  North  America,  which  stands  as  the  Mesozoic 
time  boundary,  is  the  Laramide  system  already  described,  explained,  and 
illustrated  on  pages  359-364.  The  system  includes  the  Wasatch  range,, 
and  others  to  the  north  and  south.  Another  figure  (Fig.  1467),  representing. 
a  section  of  the  Lower  Cretaceous  in  the  eastern  mountain  range  of  Mexico,, 
northwest  of  Monterey,  is  here  added  from  a  paper  by  R.  T.  Hill.  The' 
beds  stand  in  a  series  of  nearly  vertical  anticlines  and  synclines,  froiii 

1467. 


Section  showing  the  folding  of  the  Comanche  limestone  in  the  eastern  mountain  range  northwest  of  Monterey^ 

E.  T.  Hill. 

participation  in  the  system  of  Laramide  upturnings.  A  section  showing 
vertical  beds  of  limestone  and  a  flexure  in  the  Chinate  Mountains,  25  miles 
north  of  Presidio,  not  far  from  the  boundary  of  Texas,  is  published  by 
C.  A.  White  in  his  Correlation  Report  on  the  Cretaceous  of  North  America, 
Further,  Streeruwitz  has  given  sections  illustrating  the  upturned  condition 
of  the  Cretaceous  formation  of  the  Sierra  Blanca  and  other  mountains  in 
Trans-Pecos,  or  western,  Texas. 

The  great  belt  of  orogenic  work  extending  from  the  Arctic  regions; 
through  North  America,  was  probably  paralleled  by  like  work,  of  equal 
extent,  in  South  America,  but  on  a  more  eastern  line.  A  long  lesson  with 
regard  to  the  comprehensiveness  of  mountain-making  forces  and  work  is 
afforded  by  the  single  case  of  North  America ;  and  it  comes  with  tenfold 
emphasis  if  the  western  borders  of  the  two  Americas,  through  120°  of 


MESOZOIC    TIME  —  CRETACEOUS.  875 

latitude,  or  a  third  of  the  circumference  of  the  globe,  were  undergoing 
simultaneous  orogenic  movements,  with  like  grand  results. 

The  deposit-making,  preparatory  to  the  Lararnide  system  of  ranges, 
began,  as  has  been  stated,  in  the  Cambrian,  and  went  forward,  with  some 
large  interruptions,  until  the  subsidence  in  the  geosynclines  of  deposition 
amounted  to  25,000  feet.  While  the  Laramie  epoch  was  passing,  there  was 
a  deepening  of  10,000  feet  in  some  places  during  the  Cretaceous  period  alone, 
and  in  Montana  over  7000  feet  if  the  estimates  of  thickness  are  right. 

As  once  before  stated,  it  is  not  supposable  that  the  Archaean  ridges 
bounding  such  troughs  participated  in  the  great  subsidence.  Assuming  the 
load  of  sediments  to  have  caused  the  sinking,  in  accordance  with  the  isostatic 
theory,  the  trough  would  have  been  made  in  the  waters  off  the  shores,  and 
would  have  been  greatest  a  little  distance  out  from  the  shores ;  and  the  same 
might  be  a  consequence  if  lateral  pressure  were  the  cause  of  the  subsidence. 
The  denudation  of  the  ridges  would  have  caused  them  to  rise  rather  than 
sink. 

The  earlier  movements  connected  with  the  upturning  appear  to  have 
begun  before  the  Laramie  depositions  were  completed,  producing,  according 
to  Cross,  a  small  unconformity  in  bedding  between  the  Lower  Laramie  and 
the  Denver  beds,  besides  unconformity  by  erosion.  The  latter  is  described  by 
Weed  as  marking  the  junction  of  the  Lower  Laramie  and  the  Livingston 
beds.  But  the  erosion-plane  occurs  at  a  level  200  feet  below  that  of  a 
brackish-water  bed,  abounding  in  Oyster  shells,  like  those  of  the  Lower 
Laramie,  showing  that  true  Laramie  conditions  still  prevailed,  and  that  the 
erosion  was  an  event  of  minor  importance.  If  the  orogenic  work  had  actually 
begun,  violent  currents  in  the  water  may  have  been  produced  where  quiet 
deposition  had  before  been  in  progress ;  and  then  great  excavations  of  the 
earlier-made  beds  may  have  been  occasioned,  followed  by  depositions  of  con- 
glomerates and  other  coarse  beds.  Moreover,  earthquakes  and  earthquake 
waves  from  the  adjoining  sea  may  have  been  an  agent  in  producing  erosions 
of  the  unconsolidated  strata. 

The  erosion  at  the  base  of  the  Upper  Laramie  has  been  supposed  to  amount 
to  several  thousands  of  feet  and  to  have  taken  place  as  a  result  of  an  eleva- 
tion of  the  region  to  this  height ;  and  this  elevation  has  been  thought 
necessary  for  the  supply  of  the  Paleozoic  material  of  the  conglomerates. 
But  such  a  lift  of  the  region  would  have  changed  the  climate,  and  through 
consequent  river-erosion  would  have  cut  down  the  Laramie  formation  into 
mountain  valleys  and  ridges ;  and  it  would  also  have  exterminated  the  fauna 
and  flora ;  when,  in  fact,  horned  Dinosaurs  existed  after  it,  while  the  Denver 
beds  were  in  course  of  deposition,  and  their  bones  are  associated  with  those 
of  various  other  Dinosaurs  in  regions  not  far  distant. 

Igneous  eruptions  were  also  a  feature  of  the  early  stages  of  the  orogenic 
movements,  and  also  of  its  latest.  The  Wasatch^  as  described  by  King 
(see  map,  page  360),  had  its  outflows  of  trachyte  chiefly  from  the  region 
of  greatest  wrenching  between  the  main  range  and  the  Uinta  plateau. 


376  HISTORICAL   GEOLOGY. 

The  laccoliths  of  the  Henry  Mountains  in  southern  Utah  (page  301), 
according  to  Gilbert's  descriptions,  are  other  products  of  this  time  of  dis- 
turbance; and  so  also,  as  remarked  by  Hills,  those  of  the  Spanish  Peaks  in 
southern  Colorado. 

Other  eruptions  of  the  epoch  contributed  to  the  making  of  some  of  the 
remarkable  silver  and  lead  mines  of  the  Rocky  Mountain  region.  S.  F. 
Emmons,  in  his  excellent  Keport  on  the  famous  Leadville  region  (page  340), 
briefly  considers  the  question  of  the  age  of  the  veins.  He  points  out  the 
fact  that  some  of  the  largest  eruptions  preceded  the  Laramie  upturning, 
while  others  attended  the  upturning ;  but  he  leaves  the  question  as  to  the 
precise  time  of  vein-making  undecided.  Emmons  also  considers  it  probable 
that  a  large  part  of  the  eruptive  rocks  of  Colorado  are  of  the  same  Laramide 
epoch. 

According  to  Iddings,  the  igneous  eruptions  in  Wyoming  and  Montana  and  the 
adjoining  Yellowstone  Park  went  on  near,  and  at,  the  close  of  the  Cretaceous.  The  rocks 
are  largely  andesytes  of  various  kinds,  much  like  those  of  Colorado.  They  occur  as 
dikes,  intrusive  sheets,  and  laccoliths  ;  and  later  in  the  epoch  of  eruption,  probably  in  the 
early  Tertiary,  volcanic  cones  were  thrown  up.  In  Montana  similar  eruptive  conditions, 
of  the  same  epoch,  have  been  observed  by  J.  E.  Wolff  (1892)  in  the  Crazy  Mountains, 
producing  intrusive  sheets ;  and  among  the  rocks  occur  elseolite  syenyte,  and  varieties 
containing  neph elite  and  sodalite.  Similar  rocks  occur,  according  to  Lindgren  (1890, 
1893),  in  the  Highwood  Mountains,  farther  north. 

The  occurrence  of  dikes  of  sandstone,  as  described  by  Cross  (1894),  in  the  granite  of 
the  region  of  Pike's  Peak,  evidently  filling  fissures  in  the  granite,  may  be  mentioned  here, 
although  their  time  of  origin  is  uncertain.  They  occur  on  the  west  side  of  the  Manitou 
Park.  They  are  narrower  below,  and  sometimes  branch  downward.  The  width  varies 
from  300  yards  to  a  few  inches  and  even  a  thin  film.  The  rock  is  an  even-grained 
quartzose  sandstone,  usually  as  hard  as  quartzyte,  with  some  limonite  among  the  grains 
as  cement. 

In  India  the  eruption  of  the  "Deccan  traps,"  the  most  enormous  on 
record,  took  place  probably,  according  to  Blanford,  at  or  near  the  close  of 
the  Cretaceous.  The  facts  are  mentioned  on  page  299,  under  the  subject  of 
non-volcanic  igneous  eruptions.  The  eruptions  at  the  close  of  Mesozoic  time 
mark  the  commencement  of  an  eruptive  period  in  the  earth's  history,  which 
had  its  maximum  effects  during  the  following  Tertiary  period. 

Disappearance  of  species.  —  The  disappearance  of  species  at  the  close  of 
Mesozoic  time  was  one  of  the  two  most  noted  in  all  geological  history. 
Probably  not  a  tenth  part  of  the  animal  species  of  the  world  disappeared  at 
the  time,  and  far  less  of  the  vegetable  life  and  terrestrial  Invertebrates ; 
yet  the  change  was  so  comprehensive  that  no  Cretaceous  species  of  Vertebrate 
is  yet  known  to  occur  in  the  rocks  of  the  American  Tertiary,  and  not  even 
a  marine  Invertebrate.  The  only  species  in  North  America  known  to  have 
continued  on  into  the  Tertiary  are  plants,  some  of  which  existed  still  in  the 
Miocene,  and  a  few  differ  little  from  existing  species.  Here  ended  not  only 
the  living  species  of  Dinosaurs,  of  Mosasaurs,  and  Pterosaurs,  but  these 
tribes  of  Reptiles.  This  was  true  also  of  the  Belemnites,  so  far  as 


MESOZOIC   TIME CRETACEOUS.  877 

fossils  give  information,  and,  with  a  single  doubtful  exception,  of  the  Am- 
monites ;  and,  among  other  Mollusks,  of  the  genera  Exogyra,  Diceras,. 
Requienia,  Hippurites,  Radiolites,  Pterinea,  Inoceramus,  and  others.  Part 
of  the  change  had  been  accomplished  before  the  time  of  the  catastrophe, 
for  decline  had  made  much  progress  in  the  Cycads,  Ammonites,  Belemnites,. 
and  in  the  Reptilian  tribes.  But  still  the  destruction  was  great,  world-wide,, 
one  of  the  most  marvelous  events  in  geological  history.  Among  the  larger 
land  animals  the  species  most  likely  to  have  escaped  extermination  are  the 
Mammals  ;  for  many  of  them  had  no  doubt  already  accustomed  themselves  to 
the  higher  lands  or  ridges  of  the  continents,  and  their  covering  of  fur  would 
have  made  adaptation  to  a  colder  climate  easy.  The  Birds  also  would  have 
been  to  a  large  extent  tenants  of  the  interior  and  denser  forests  of  the  con- 
tinent of  the  time.  The  Pterosaurs  might  have  had,  perhaps,  an  equal 
chance  with  the  Birds,  but  for  the  absence  of  a  coat  of  feathers. 

As  to  the  cause  of  the  epochal  disappearance  of  species,  the  remarks  on 
the  like  event  after  the  Appalachian  revolution,  on  page  735,  apply  also  here. 

The  Laramide  orogenic  disturbance  in  America  passed  with  no  marked 
contemporary  movements  in  Europe,  none  sufficient  to  account  for  the 
thoroughness  of  the  disappearance  of  species.  Change  by  modification  had 
its  marked  effects,  for  it  has  always  been  in  progress ;  but  extermination 
must  have  been  the  more  prominent  method  of  bringing  about  the  great 
result. 

Causes  of  extermination. —  Since  the  destructions  were  to  a  very  large 
extent  marine,  the  oceanic  circulation  was  probably  one  means  of  destruc- 
tion. The  world,  by  the  end  of  the  Cretaceous  period,  had  become  more 
diversified  than  ever  before  in  its  zones  of  temperature.  The  emergence 
from  the  ocean  of  a  third  of  North  America  had  taken  place,  and  probably 
of  as  much  of  South  America,  and  of  large  portions  also  of  the  other  con- 
tinents, and  this  would  have  determined  some  lowering  of  the  earth's  mean 
temperature,  cooling  both  the  air  and  oceanic  waters.  The  cooling,  during 
the  Cretaceous  period,  it  is  certain,  was  great  enough  to  drive  Cycads  from 
the  Arctic  regions  to  latitudes  that  are  now  at  the  middle  of  the  Temperate- 
Zone.  If  the  change  had  made  the  Arctic  waters  only  15°  F.  colder  than, 
they  were  during  the  Cretaceous  period,  the  polar  waters,  as  they  flowed 
southward,  would  probably  have  been  exterminating  to  the  greater  part  of  the^ 
life  of  coast  regions  along  the  shallower  waters,  and  down  to  such  depths  as. 
the  cold  current  reached.  Such  a  cause  might  make  a  complete  break  in  the 
succession  of  species  in  a  region,  without  any  break  in  the  succession  of  beds, 
as  happened  in  New  Jersey  (page  821).  Its  action  would  have  been  least  on 
the  western  coast  of  North  America,  because  of  the  shallowness  of  Bering 
Strait.  Moreover,  under  these  circumstances  temperature  would  have 
worked  similarly  over  the  land,  forcing  Cycads  southward,  and  putting 
unfavorable  conditions  into  the  old  haunts  of  Reptile  life. 

The  other  most  probable  cause  of  destruction  to  life  is  that  from  earth- 
quake waves.  The  making  of  a  mountain  system  along  the  whole  length  of 


$78  HISTORICAL   GEOLOGY. 

a  continent,  causing  displacements  of  the  rock  formations  along  lines 
measuring  hundreds  of  miles  in  extent,  must  have  been  attended  by  a 
succession  of  earthquakes  of  unwonted  violence,  which  would  have  caused 
•destruction  by  the  vibrations  in  the  rocks  beneath,  and  also  indirectly  through 
the  deluging  waves  sent  careering  over  the  land  from  any  seas  in  the  range 
of  the  vibrations.  Whenever  the  shakings  of  the  continent  extended 
beneath  the  ocean,  these  deluges  from  earthquakes  of  Laramide  origin  would 
have  been  destructive  over  all  the  coasts  of  a  hemisphere.  As  land  was 
mostly  low  at  the  time,  the  earthquake  waves  may  have  made  their  marches 
inland  for  hundreds  of  miles,  and  have  left  alive  only  the  smaller  animal 
species  and  the  vegetation. 

This  sweeping  from  the  world  of  so  large  a  part  of  its  life,  and  especially 
that  of  Mesozoic  characteristics,  was  a  much-needed  preparation  for  the  era 
of  the  "Reign  of  Mammals."  It  was  an  opportunity  for  the  "survival  of 
the  fittest "  on  a  grand  scale ;  that  is,  the  survival  of  those  species  that  could 
withstand  the  special  causes  of  destruction,  and  of  the  many  that  were  out 
of  harm's  way.  The  exterminations  were  the  removals  of  hindrances  to 
progress.  The  survival  of  the  fittest  and  of  the  lucky  ones,  while  not  directly 
species-making,  was  the  origin  of  new  associations  in  continental  and  oceanic 
life ;  that  is,  of  new  faunas  and  new  floras  over  the  world,  in  which,  under 
the  modified  geographical  and  physical  conditions,  the  elements  existed  for 
further  change  and  progress. 


IV.    CENOZOIC   TIME. 

It  has  been  observed  that,  before  the  close  of  Mesozoic  time,  the  medieval 
features  of  the  era  were  already  passing  away.  The  Cycads  had  mostly 
given  place  to  the  Sassafras,  Tulip  tree,  Willow,  Maple,  Oak,  and  Palm ;  the 
ancient  type  of  Ganoids,  to  Salmon,  Perch,  and  Herring ;  and  the  Corals, 
Echini,  and  Mollusks  had  close  relations  to  those  of  existing  seas,  though  of 
•extinct  species.  But,  notwithstanding  these  changes,  the  Mesozoic  aspect 
continued  to  the  end.  Even  the  little  Mammals,  which  appeared  among  the 
Reptiles,  bore  the  mark  of  the  age,  for  they  approximated  to  the  oviparous 
Reptiles  and  Birds,  in  being  themselves  either  semioviparous  or  oviparous ; 
that  is,  either  Marsupials  or  Monotremes. 

But  with  the  opening  of  the  new  era,  the  Mammals  in  their  turn  became 
the  dominant  race.  Types  much  like  those  of  the  age  of  Man  were  multi- 
plied among  them,  in  all  departments  of  nature.  As  the  era  advanced, 
•the  first  of  the  species  now  living  appeared,  —  a  few  among  multitudes  that 
became  extinct ;  and  afterward  a  larger  proportion ;  and,  before  it  closed, 
nearly  all  kinds  of  life,  excepting  Mammals,  were  identical  with  those  of  the 
present  era.  As  the  Paleozoic  or  ancient  life  was  followed  by  the  Mesozoic 
or  Medieval,  so  now  there  was  as  marked  a  change  to  the  Cenozoic  or  recent 
life  and  world. 

Cenozoic  time  embraces  two  eras :  — 

I.    The  TERTIARY,  or  era  of  Mammals. 
II.   The  QUATERNARY,  or  era  of  Man. 

These  eras,  like  consecutive  eras  in  preceding  time,  were  continuous  in 
life  through  both  the  vegetable  and  animal  kingdoms,  and  it  is  not  proved 
that  Man,  the  most  characteristic  feature  of  the  Quaternary,  was  not  in 
existence  before  the  close  of  the  Tertiary.  But  one  of  the  grandest  and 
most  sweeping  catastrophic  epochs  intervened  between  the  two,  the  Glacial, 
.and  so  separated  them,  although  the  destructive  influence  of  this  epoch  did 
not  extend  over  tropical  regions,  except  in  the  vicinity  of  lofty  mountains. 

TERTIARY   ERA. 

The  Mammals  of  the  Tertiary  era  are  all  extinct ;  and  the  proportion  of 
living  Invertebrates,  the  Protozoans  excluded,  varies  from  none  in  the 
earlier  part  of  the  era  to  95  per  cent  in  the  later  part.  The  Early  and 
Middle  Quaternary  Mammals  are  largely  extinct,  but  the  Invertebrates 
and  Plants  are  existing  species.  The  Later  Quaternary  or  Recent  animals 
and  plants  are  of  existing  species,  except  those  that  have  become  extinct 
through  the  agency  of  man. 


880  HISTORICAL  GEOLOGY. 

GENERAL  SUBDIVISIONS. 

The  subdivisions  of  the  Tertiary  in  general  use  were  introduced  by  Lyell 
in  the  first  edition  of  his  Geology.  They  were  based  by  him  primarily  on 
his  own  geological  investigations  in  England  and  Europe,  and  on  those  of 
the  French  conchologist,  Deshayes,  who  was  already  familiar  with  the  fossil 
species  of  the  Paris  Basin.  The  proportion  of  living  to  extinct  species  was 
accepted  as  the  distinctive  character  of  the  subdivisions.  These  subdivisions, 
and  the  proportions  now  adopted  for  the  approximate  limits,  are  as  follows  :  — 

1.  EOCENE  period  (from  ^d>s,  dawn,  and  KCUVO?,  recent)  :  no  species,  or  less 
than  5  per  cent  living. 

2.  MIOCENE  period  (from  //.eiW,  less,  and  KCUVOS)  :  20  to  40  per  cent  living. 

3.  PLIOCENE  period  (from  TrActW,  more,  and  KCUI/OS)  :  more  than  half  the 
species  living. 

The  Miocene  and  Pliocene  are  sometimes  united  under  the  name  NEOCENE 
(from  j/eos,  new,  and  /«ui/os),  especially  when  the  divisions  are  not  well  differ- 
entiated. The  term  Oligocene  (from  oAtyos,  few,  and  KCUI/OS)  is  sometimes 
used  for  a  fourth  division,  consisting  of  the  upper  part  of  the  Eocene  and  the 
lower  part  of  what  had  been  referred  to  the  Miocene. 

The  term  Oligocene  was  proposed  by  Beyrich,  of  Berlin,  in  1855.  In  1864,  Homes,, 
of  Vienna,  proposed  the  term  Palaeogene  for  the  combined  Eocene  and  Oligocene,  and 
Neogene  for  the  Miocene  and  Pliocene  ;  Eogene  has  also  been  used  in  place  of  Palaeogene. 
Further,  the  Lower  Eocene  has  also  received  the  separate  name  of  Paleocene.  J.  W. 
Dawson  adopted,  in  1889,  the  term  Orthrocene  for  the  Lower  Eocene,  Nummulitic  for  the 
Middle,  and  Proicene  for  the  Upper  or  (as  he  says)  that  of  the  Vicksburg  Epoch. 

On  the  geological  map  published  in  1884  by  the  U.  S.  Geological  Survey,  Eocene 
includes  the  Eocene  and  Oligocene,  and  Neocene  the  Miocene  and  Pliocene.  In  1887, 
Heilprin  proposed  the  substitution  of  Eogene,  Metagene,  and  Neogene,  severally,  for 
Eocene  +  Oligocene,  Miocene,  and  Pliocene  +  Quaternary. 

The  name  Tertiary  is  a  relic  of  early  geological  science.  When  introduced,  it  was 
preceded  in  the  system  by  Primary  and  Secondary.  The  first  of  these  terms  was  thrown 
out  when  the  crystalline  rocks  so  called  were  proved  to  belong  to  no  particular  age,  — 
though  not  without  an  ineffectual  attempt  to  substitute  for  it  Paleozoic;  and  the  second, 
after  use  for  a  while  under  a  restricted  signification,  has  given  way  to  Mesozoic.  Tertiary 
holds  its  place,  simply  because  of  the  convenience  of  continuing  an  accepted  name.  Neo- 
zoic is  sometimes  used  in  place  of  Tertiary,  while  it  is  also  occasionally  made  a  substitute 
for  the  whole  Cenozoic.  It  was  originally  proposed  by  Edward  Forbes  to  comprise  both 
the  Mesozoic  and  Cenozoic. 

NORTH   AMERICA. 
GENERAL   GEOGRAPHICAL   FEATURES  OF   THE  TERTIARY  ERA. 

It  has  been  shown  that  the  deposition  of  the  Laramie  beds  and  the  up- 
turning which  followed  left  the  great  interior  of  North  America  emerged. 
The  Cretaceous  sea,  which  had  covered  the  Western  Continental  Interior  and 
the  Rocky  Summit  region  from  Mexico  to  the  Arctic  coast,  was  gone,  excepting; 


CENOZOIC    TIME — TERTIARY. 


881 


a  large  bay  on  the  Arctic  shores,  and  an  extended  "  Gulf  of  Mexico  "  at  its 
southern  limit.  Isolated  salt  lakes  probably  remained  for  a  while  over  the 
Interior,  of  which  Great  Salt  Lake  of  Utah  is  the  last  survivor;  but  no 
marine  Tertiary  strata  found  in  and  about  them  are  known  to  exist. 

The  submerged  portions  of  the  continent,  or  the  areas  of  marine  rock 
making,  were  therefore  confined  to  the  borders  of  the  continent,  —  the 
Atlantic  border,  the  Gulf  border,  and  the  Pacific  border.  This  general 
condition  of  the  continent  during  the  early  Tertiary  is  represented  on  the 
accompanying  map,  Fig.  1468. 

1468. 


Map  of  North  America  showing  the  parts  under  water  in  the  Tertiary  Era ;  the  vertically -lined  is  the  Eocene  ; 
the  horizontally  -lined,  the  Miocene  or  Miocene  and  Pliocene ;  the  cross-lined,  the  Eocene  and  later  Tertiary. 

It  is  observed  on  the  map  that  the  condition  of  the  Atlantic  border  was 
much  like  that  of  the  Cretaceous  period ;  that  Florida  was  under  water,  as 
then,  and  that  the  Mississippi  bay  was  scarcely  diminished  in  extent  during 
the  time  of  greatest  submergence. 

The  portions  of  the  Tertiary  area  which  are  lined  vertically  are  those 
of  the  Eocene  beds,  and  those  lined  horizontally,  of  the  Miocene  or  Mio- 
cene and  Pliocene.  The  map  thus  indicates  the  fact  that  along  the  Atlantic 
coast  region  the  sea  had  nearly  the  same  limit  through  both  the  Eocene  and 
Miocene  periods ;  but  that  on  the  Gulf  border  a  great  retreat  of  the  waters 
took  place  before  the  beginning  of  the  Miocene. 

On  the  Atlantic  border  northeast  of  New  Jersey,  Tertiary  beds  have  been 
identified  by  fossils  only  on  Martha's  Vineyard;  and,. doubtfully,  through 
shells  brought  up  by  the  dredge,  on  St.  George's  Shoal,  east  of  Cape  Cod, 
DANA'S  MANUAL  —  56 


882  HISTORICAL   GEOLOGY. 

and  at  one  place  on  the  Banks  of  Newfoundland.  Their  absence  from  the 
coast  region  in  the  higher  latitude  may  be  owing,  as  generally  believed,  to 
the  present  submergence  of  the  border  on  which  such  beds  were  deposited. 
But  the  existence,  for  the  most  part,  of  rapidly  deepening  waters  north  of 
Newfoundland,  and  the  denuding  power  of  the  waves  of  the  open  ocean  may 
have  been  the  effective  cause  along  much  of  the  coast. 

Although  the  ocean  had  been  excluded  from  the  Continental  Interior  at 
the  close  of  the  Cretaceous  period,  rock-making  was  still  carried  forward  over 
much  of  its  area  by  means  of  vast  freshwater  lakes.  These  lakes  had  their 
Fishes  and  other  aquatic  life,  and  their  borders  were  frequented  by  various 
^animals  of  the  land,  including  Mammals  of  many  species,  with  various  small 
Reptiles,  and  the  remains  of  these  species  abound  in  the  lacustrine  deposits. 
The  freshwater  Tertiary  formations  have  consequently  an  importance  not 
inferior  to  that  of  the  marine  beds. 

The  great  lakes  of  the  earlier  Tertiary  —  the  Eocene  —  were  situated  in 
the  Rocky  Summit  region,  within  the  United  States,  mostly  over  the  area  of 
the  Laramide  mountain  system.  One  Eocene  lake,  the  Wasatch  (W  on  the 
map),  covered  a  large  region  north  of  the  Uinta  Mountains,  between  the 
parallels  of  40°  and  44°,  including  parts  of  Utah,  Wyoming,  and  a  portion  of 
northwestern  Colorado;  and  as  the  earlier  Wasatch  Lake  narrowed  its  limits 
in  the  later  Eocene,  it  became  the  Bridger  Lake.  The  "  Green  River  basin  " 
was  part  of  the  Wasatch.  Another,  the  Uinta  Lake  (U),  lay  south  of  the 
Uinta  Mountains,  chiefly  within  the  boundaries  of  Utah.  Another  smaller 
lake,  the  Puerco  (P),  was  situated  in  the  northern  part  of  New  Mexico,  and 
extended  across  the  border  into  Colorado.  Two  others,  of  small  size,  were 
situated  in  the  region  of  the  Great  Basin  west  of  Great  Salt  Lake. 

The  lacustrine  beds  of  Wasatch  Lake  occupy  a  plateau  region  about  6500 
feet  (6000  to  7000)  above  the 'sea  level.  The  height  of  the  village  of  Green 
River,  within  the  former,  above  tide  level,  is  6140  feet ;  of  Bridger,  6780  feet ; 
of  Wasatch,  6789  feet. 

Nearly  all  the  later  Tertiary  lake  basins  lie  either  to  the  east  or  west  of 
the  Summit  region,  over  Nebraska  and  the  adjoining  states  on  the  eastern 
slope  of  the  Rocky  Mountains,  or  between  nearly  the  same  parallels  but 
farther  west ;  part  of  them  in  the  Oregon  and  Nevada  portions  of  the  Great 
Basin  region.  The  extent  of  the  Eocene  lakes  over  the  Summit  region  is 
regarded  as  evidence  that  the  general  mass  of  the  mountains  at  the  time 
stood  but  little  above  the  sea  level.  The  great  thickness  which  the  beds 
attained  in  the  course  of  the  Eocene  is  proof  that  the  areas  were  undergoing 
a  slow  subsidence,  keeping  pace  with  the  deposition,  while  their  borders  were 
essentially  stable ;  and  that  the  position  of  the  area  of  maximum  subsidence 
changed  in  the  course  of  the  Eocene  period.  Further,  the  position  and  great 
extent  of  the  Miocene  lakes,  covering  a  large  part  of  the  eastern  slope  of  the 
mountains,  are  evidence  that  the  elevation  which  took  place  at  the  close  of 
the  Eocene,  draining  the  lake  basin,  was  small. 

All  the  land  of  the  Tertiary  continent  had  its  working  streams  and 


CENOZOIC    TIME  —  TERTIARY.  883 

streamlets,  denuding,  transporting,  making  alluvial  deposits,  and  carrying 
sediments  to  the  seashores;  and  the  whole  surface  was  well  populated, 
beyond  doubt,  by  Mammals,  Birds,  and  inferior  terrestrial  life.  The  moun- 
tains of  the  Appalachian  System  and  its  bordering  regions  on  the  east, 
west,  and  south  contributed  material  for  the  marine  Tertiary  beds  of  the 
Atlantic  and  Gulf  borders;  the  weakly  consolidated  beds  of  the  recently 
made  Laramide  mountain  ranges  afforded  the  same  more  abundantly  for  the 
thick  deposits  of  the  vast  freshwater  lakes  about  the  summit  of  the  Rocky 
Mountains  and  over  its  eastern  slopes;  and  the  Sierra  Nevada  and  other 
ranges  of  the  western  slopes  were  a  source  of  supply  for  other  lakes  and  for 
the  marine  Tertiary  of  the  Pacific  border.  But  notwithstanding  the  work 
of  rivers  and  other  agencies,  there  have  not  been  found,  up  to  1894,  over 
the  eastern  half  of  the  continent  away  from  the  sea  border,  any  recognizable 
fossil-bearing,  lacustrine  Tertiary  deposits,  excepting  over  small  spots  near 
the  center  of  the  state  of  Vermont.  In  the  western  half  of  the  continent, 
the  only  fluvial  beds  recognized  as  Tertiary,  by  means  of  fossils,  are  those 
of  the  auriferous  gravels  of  the  Sierra  Nevada.  Nothing  of  Tertiary  origin 
has  yet  been  identified  in  or  about  the  basin  of  Hudson  Bay,  or  those  of  the 
Great  Lakes,  or  in  limestone  caverns  of  the  Mississippi  valley  and  elsewhere, 
to  prove  that  these  basins  and  caverns  were  in  existence  during  Tertiary 
time.  They  may  have  existed,  but  the  proof  is  wanting. 

This  work  is  indebted  for  the  preceding  Tertiary  map  of  North  America  to  G.  D. 
Harris,  who  has  prepared  it  from  earlier  maps  and  publications,  from  unpublished  records 
of  the  U.  S.  Geological  Survey,  and  to  a  considerable  extent  also  from  his  own  personal 
study  of  the  marine  Tertiary  along  the  Atlantic  and  Gulf  borders.  Further,  the  subdi- 
visions of  the  eastern  Tertiary  adopted  beyond,  and  the  remarks  on  the  distribution  of 
the  beds,  are  partly  from  his  manuscript  notes.  In  addition,  he  has  revised  the  pages  on 
the  Invertebrate  paleontology,  of  the  same  region  ;  and  part  of  its  illustrations  are  from 
his  work  on  the  Tertiary  Paleontology  of  Texas.  A  list  of  earlier  publications  and  a 
review  of  the  facts  and  of  the  question  of  equivalency  may  be  found  in  the  U.  S.  Gr.  S. 
Bulletin,  No.  83,  by  W.  B.  Clarke,  on  the- Correlation  of  the  Eocene  Tertiary,  1891,  and 
in  the  U.  S.  G.  8.  Bulletin,  No.  84,  on  the  Correlation  of  the  Neocene,  by  William  H.  Ball 
and  G.  D.  Harris,  1892. 

SUBDIVISIONS. 

The  periods  of  the  Tertiary  era  proposed  by  Lyell  are  the  basis  of  the 
American  subdivisions,  namely :  (1)  EOCENE,  (2)  MIOCENE,  (3)  PLIOCENE. 
To  these  are  added  by  some,  OLIGOCENE,  corresponding  in  age  to  the  Euro- 
pean Oligocene.  NEOCENE  is  also  sometimes  used  for  the  Miocene  and 
Pliocene. 

The  marine  and  lacustrine  formations  are  independent  in  fossils,  and 
besides  are  nowhere  interstratified,  and  hence  it  is  not  possible  to  make  out 
their  precise  equivalents.  As  regards  the  lacustrine  beds,  even  the  division 
into  periods  is  based  largely  on  facts  from  Europe.  Moreover,  the  species 
of  the  marine  Tertiary  of  the  Atlantic  and  Pacific  borders  are  almost  wholly 


884 


HISTORICAL   GEOLOGY. 


different ;  and  besides,  those  of  the  latter  thus  far  make  but  one  group  for 
the  Eocene,  and  one  for  the  Miocene.  For  these  reasons,  the  three  regions, 
the  Atlantic  and  Gulf  borders,  the  Pacific  border,  and  the  Lacustrine  areas, 
are  independent  in  their  subdivisions  and  cannot  be  satisfactorily  correlated. 
They  are  brought  together,  however,  in  the  following  table,  to  exhibit  the 
general  relations  of  the  subdivisions,  and  nothing  more.  It  is  not  yet  known 
in  all  cases  what  subdivisions  of  the  Eocene  formations  recognized  on  the 
coast  are  equivalents  of  the  Lower,  Middle,  and  Upper  Tertiary  in  the 
Continental  Interior. 

TABLE  OF  APPROXIMATE  EQUIVALENCY  OF  THE  SUBDIVISIONS. 


Atlantic  and  Gulf  borders 

Lacustrine  areas 

Pacific  border 

Foreign 

Pliocene 

Floridian 

Blanco 
Palo  Duro 

Pliocene 

Pliocene 

Miocene 

Yorktown 
Chipola 
Chattahoochee 

Loup  Fork 
John  Day 
White  River 

Miocene 

Tortonian 
Aquitanian 

Eocene 

Upper,      Vicksburg 

Uinta 

Tongrian 
Ligurian 

r  Jackson 
Middle   \  Claiborne 
t  Lower  Claiborne 

Bridger 
Wind  Eiver 

Tejon 

Parisian,  or  Calcaire 
Grossier 

(  Lignitic 
L°wer    1  Midway 

Wasatch 
Puerco 

Suessonian 
Cernaysian 

a.    MARINE  TERTIARY  OF  THE  ATLANTIC  AND  GULP  BORDERS. 

3.   Pliocene  period. 

FLORIDIAN  EPOCH.  Floridian  of  Heilprin,  as  modified  by  Dall.  — 
Merced  group  of  the  peninsula  of  San  Francisco,  of  A.  C.  Lawson. 

2.   Miocene  period. 

3.  YORKTOWN  EPOCH.  So  named  from  Yorktown,  Va.,  Dana's 
Geol,  1863.  Chesapeake  of  Darton  and  Dall,  1891. 

2.  CHIPOLA  EPOCH.  Kepresented  by  the  Chipola  group  of  Burns, 
occurring  along  the  Chipola  River,  Florida. 

1.  CHATTAHOOCHEE  EPOCH.  Chattahoochee  of  Langdon,  named 
from  typical  exposures  on  the  Chattahoochee  Eiver  in  southwest 
Georgia  and  northwest  Florida. 

1.   Eocene  period. 

6.  VICKSBURG  EPOCH.  Vicksburg  of  Conrad  ;  named  from  beds  at 
Vicksburg,  Miss. 

5.    JACKSON  EPOCH.      Jackson  of  Conrad,  exposed  near  Jackson,, 

Miss. 


CENOZOIC   TIME  —  TERTIARY.  885 

4.  CLAIBORNE  EPOCH.  Upper  part  of  Claiborne  of  Conrad,  oc- 
curring along  the  Alabama  and  Tombigbee  rivers  (Langdon),  and  in 
Arkansas. 

3.  LOWER  CLAIBORNE  EPOCH.  Part  of  the  Claiborne  of  Conrad, 
separated  here  by  Harris;  occurs  in  Alabama,  Georgia,  and  South 
Carolina,  and  includes  the  Buhrstone  of  Tuomey  and  Lyell,  and  the 
Siliceous  and  Calcareous  Claiborne  of  Mississippi. 

2.  LIGNITIC  EPOCH.  Represented  by  the  Lignitic  beds,  in  part,  of 
Conrad  and  Hilgard,  including  the  beds  between  the  Buhrstone  and 
the  Matthews  Landing  clays,  as  restricted  by  Harris ;  La  Grange 
group,  in  part,  of  Safford ;  Eolignitic,  in  part,  of  Heilprin. 

1.  MIDWAY  EPOCH.     Part  of  the  Lignitic  of  Conrad,  and  of  Smith 
and  Johnson ;  represented  by  the  Calcareous  beds  near  Midway,  and 
the  Matthews  Landing  clays,  on  the  Alabama  River. 

6.    MARINE  TERTIARY  OF  THE  PACIFIC  BORDER. 

3.   Pliocene  period. 

Represented  by  local  deposits  in  California,  Oregon,  and 
Washington. 

2.  Miocene  period. 

Represented  by  deposits  in  the  coast  region  of  California,  which 
partly  constitute  the  Coast  Range  at  Astoria,  Oregon,  on  the  Columbia 
River,  and  also  in  Washington,  to  the  north. 

1.  Eocene  period. 

Represented  by  the  Tejon  group  of  J.  D.  Whitney  (1869),  named 
from  the  locality  near  Fort  Tejon,  Kern  County,  Cal. ;  beds  occur  es- 
pecially along  the  east  side  of  the  Coast  Range,  near  Astoria,  Oregon. 

c.    LACUSTRINE  TERTIARY. 

3.  Pliocene  period. 

2.  Blanco  group  of  Cummins  and  Cope  (1892),  occurring  at  Blanco 
Canon,  Crosby  County,  Tex.,  and  extending  northward  along  the  Staked 
Plains  beyond  Red  River. 

1.  Palo  Duro  beds  of  Scott ;  Good-night  beds  of  Cummins  ;  observed 
near  the  Canon  of  Palo  Duro  in  Texas,  and  also  in  northern  Kansas. 

2.  Miocene  period. 

3.    UPPER  MIOCENE.     Loup  Fork  group  of  Meek  and  Hayden. 

2.  Loup  Fork  beds:  On  Loup  Fork  of  Platte  River  in  central 
Nebraska,  but  extending  southward  interruptedly  to  Mexico,  and 
occurring  in  New  Mexico  on  the  Rio  Grande,  Gila,  and  San  Fran- 
cisco rivers.  Pliocene  and  Pliohippus  beds  of  Marsh. 


886  HISTORICAL   GEOLOGY. 

1.  Deep  River  beds,  the  Cyclopidius  beds  of  Scott,  in  the  Deep 
River  (or  Deep  Creek)   region,  which  are  overlaid  by  beds  with 
Loup  Fork  fossils.      Ticlioleptus  beds  of  Cope,  but  not  those  so 
named  of  Wyoming  and  Oregon. 

2.  MIDDLE  MIOCENE.     Miohippus  beds  and  John  Day  beds  of  Marsh 
(1877),  occurring  on  John  Day  River,  Oregon. 

1.  LOWER  MIOCENE.      White  River  beds  of  Hayden  (1857) ;  Oligocene 
of  Scott. 

3.  Protoceras  beds  of  Wortman,  of  the  White  Eiver  region. 

2.  Oreodon  beds  of  Marsh  (1877),  in  the  White  River  basin. 

1.  Titanotherium   beds  of   Hayden   (1857,  1869),  in   the  White 
Eiver  region  on  the  Mobrara,  and  in  Dakota  and  Colorado.     Bronto- 
therium  beds  of  Marsh. 

1.   Eocene  period. 

3.  UPPER  EOCENE. 

4.  Uinta  group  of  Marsh  (1871),  and  of  King  (1878),  lying  to 
the  south  of  the  Uinta  Mountains  in  Utah  (U  on  the  map,  page  881). 
Diplacodon  beds  of  Marsh  (1877)  ;  includes  the  Brown's  Park  group 
of   Powell    (1876).      The  Florissant  .group  of   South   Park,   Col. 
The   Amyzon   beds  of  Elko  and  Osino,  Nev.,  are  referred  to  the 
top  of  the  Uinta  or  base  of  the  Miocene. 

2.  MIDDLE  EOCENE. 

3.  Bridger  group  of  Hayden  (1869),  named  from  Fort  Bridger, 
Wyoming,  represented  to  the  north  of  the  Uinta  Mountains  over- 
lying the  Wasatch  beds.     Dinoceras  beds  of  Marsh.     Green  River 
group  of  Hayden   (1869)  is  included ;  probably  also  the  Washakie 
group  of  King  (1878).     The  Wind  River  group  of  Hayden  (1861) 
has  been  referred  to  the  bottom  of  the  Bridger  by  Scott  and  Osborn, 
and  made  the  equivalent  of  the  Green  River  group ;  but  to  the  top 
of  the  Wasatch  by  Cope. 

1.    LOWER  EOCENE. 

2.  Wasatch  group  of  Hayden   (1870),  covering  parts  of  Utah, 
Wyoming,  and  Colorado.     Coryphodon  beds  of  Marsh.     Vermilion 
group  of  King.     Bitter  Creek  group  of  Powell. 

1.  Puerco  group  of  Cope  (1875),  named  from  Puerco  River,  New 
Mexico,  occupying  a  basin  extending  from  northern  New  Mexico 
into  southern  Colorado  (P,  map).  Lower  Wasatch  of  Marsh. 

ROCKS  — KINDS   AND  DISTRIBUTION. 

The  beds,  especially  the  marine,  commonly  vary  much  in  character 
from  mile  to  mile.  Instead  of  great  strata  of  almost  continental  extent  and 
uniformity,  as  in  the  Silurian,  there  is  the  diversity  which  exists  among 
the  modern  formations  of  the  seacoast.  But  yet  such  diversity  is  not 


CENOZOIC    TIME  —  TERTIARY.  887 

universal,  for  in  some  regions  the  sands  from  shells  and  corals  were  made 
into  hard  limestones,  as  they  are  now,  and  over  areas  of  great  extent. 
Moreover,  firm  shales  and  sandstones  occur  that  are  like  those  of  early  time. 
Besides,  there  are  thick  beds  of  greensand,  like  those  of  the  Cretaceous 
formation  in  constitution,  and  equally  valuable  as  a  fertilizer.  There  are 
also  beds  of  coal  or  lignite  associated  with  some  of  the  deposits. 

Beds  of  siliceous  organisms,  Diatoms,  Radiolarians,  and  Sponge  spiculesr 
have  sometimes  much  thickness,  and  are  occasionally  partly  consolidated 
into  opal. 

The  rocks  of  the  lacustrine  and  terrestrial  deposits  are  generally  fine- 
grained, and  either  feebly  indurated  sandstones,  soft  straticulate  clays 
passing  into  shales,  or  soft  fragile  limestones  of  fine  grain;  but  these 
soft  kinds  graduate  into  harder  and  sometimes  into  coarser  varieties. 
They  have  derived  their  great  thickness  in  the  usual  way;  that  is,  through 
a  gradual  subsidence  attending  the  deposition  from  waters  of  the  region. 
On  the  coast  of  Florida,  some  beds  have  been  converted  partially  into 
phosphates  (or  phosphatized) ,  by  water  filtrating  through  overlying  guano 
deposits.  In  the  Rocky  Mountain  region  and  over  the  Pacific  slope  occur 
deposits,  sometimes  hundreds  or  thousands  of  feet  thick,  made  of  volcanic 
ashes.  There  are  also  coarse  volcanic  conglomerates  or  breccia.  The 
volcanic  beds  sometimes  cover  the  stumps  of  many  successive  growths 
of  forests  (page  135) ;  and  the  finer  kinds  occasionally  contain  remains  of 
the  Beetles,  Butterflies,  and  other  Insects  of  the  period. 

Lignite  beds  also  occur  locally  over  the  country.  One  of  the  most  noted 
of  them  is  that  of  Brandon,  Vt.,  which  is  probably  of  Eocene  origin.  It 
is  associated  with  a  bed  of  limonite. 

Denudation  was  universal  over  the  exposed  continental  surface,  as  in 
all  past  time,  dissecting  and  degrading  mountains,  and  making  fluvial 
deposits  as  well  as  lacustrine.  The  Auriferous  gravels  of  the  western 
slope  of  the  Sierra  Nevada  are  largely  fluvial  deposits  of  Tertiary  origin, 
as  shown  by  J.  D.  Whitney  in  his  Geological  Report  on  California  (1865), 
and  much  more  fully  in  his  Auriferous  Gravels  of  the  Sierra  Nevada 
(1880).  The  plants  found  in  the  gravel  beds  indicate,  according  to  Les- 
quereux,  a  Miocene  and  Pliocene  age;  but  Whitney  regards  the  formation 
as  representing  the  whole  of  the  Tertiary.  It  probably  began  in  the  Cre- 
taceous period.  As  Le  Conte  states,  the  detritus  of  the  old  gravels  is  in 
general  exceptionally  coarse,  showing  strong  currents. 

1.    Sea-border  Areas. 

I.  EOCENE.  —  Along  the  Atlantic  and  Gulf  borders  (see  map,  page  881), 
the  Tertiary  belt  is  very  narrow  and  interrupted  through  New  Jersey ;  it  is 
broader  in  Maryland  and  Virginia,  and  still  broader  in  South  Carolina.  But 
the  formation  is  best  displayed  on  the  Gulf  border.  The  inner  limit,  or  that 
against  the  Cretaceous  in  the  Carolinas  and  the  Gulf  region,  is  over  100  miles 


888  HISTORICAL   GEOLOGY. 

from  the  seacoast ;  and  in  the  Mississippi  valley  —  then  a  great  bay,  as  in 
the  Cretaceous  period  —  it  extends  northward  over  500  miles,  covering  on 
the  east  a  broad  portion  of  the  state  of  Tennessee,  and  reaching  into  Illinois, 
and  on  the  west,  an  eastern  portion  of  Missouri  and  Arkansas.  From  Texas 
it  extends  southward  into  Mexico. 

The  formation  exposed  to  view  from  New  Jersey  through  Virginia  con- 
sists of  sand-beds  of  different  colors,  including  greensand  or  glauconitic  beds, 
often  shell-bearing,  and  is  referred  to  the  Lignitic  Eocene.  In  South  Caro- 
lina the  exposure  reaches  nearly  to  the  coast,  and  is  more  varied  in  its  con- 
stitution. Along  the  inner  margin  occurs  a  stratum  of  Buhrstone,  about  200 
feet  thick,  a  cellular  siliceous  rock,  from  which  the  shells  have  been  dissolved 
away  by  siliceous  waters ;  and  over  this,  to  the  eastward,  occur  calcareous 
beds  with  some  greensand,  the  Santee  beds  of  Tuomey,  and  the  related  Ashley 
and  Cooper  beds,  or  beds  along  the  basins  of  the  Ashley  and  Cooper  rivers. 
On  the  Gulf  border  the  belt  averages  65  miles  in  width. 

1.  The  Midway,  the  lowest  member  of  the  Eocene,  was  named  thus  after  a  landing  on 
Alabama  River,  Wilcox  County,  Ala.,  by  Smith  and  Johnson  in  1887.     It  was  regarded 
by  them  as  a  subdivision  of  the  Lignitic  ;  it  is  made  by  Harris  to  include  the  Black  Bluff 
and  Matthews'1  Landing  beds,  and  given  coordinate  rank  with  the  Lignitic ;  the  Clayton 
or  Monterey  beds  of  Langdon. 

It  is  distinguished  from  the  Lignitic  by  (1)  its  fossil  contents  and  (2)  the  off-shore 
character  of  its  deposits.  In  the  region  of  Red  River  and  the  Mississippi  Embayment, 
marine  fossils  are  often  wanting,  and  the  beds  are  more  or  less  lignitic  ;  open  sea  deposits 
are  found  in  southeast  central  Texas,  central  Arkansas,  eastern  Alabama  and  Georgia. 
No  outcrops  of  this  group  have  been  recorded  to  the  northeast  of  the  last  mentioned  state. 
Total  thickness,  about  250'. 

2.  The  term  Lignitic  was  used  by  E.  W.  Hilgard  (1860)  for  the  Lower  Eocene  of  Mis- 
sissippi, consisting  partly  of  freshwater  lignitic  beds  and  partly  of  estuarine  fossiliferous 
deposits.     The  name  Lignitic  formation  had  been  still  earlier  used  by  Conrad  ;  and  Eo- 
lignitic  was  proposed  by  Heilprin  in  1884  ;  Lignitic  is  used  by  Smith  and  Johnson  (1887), 
to  designate  all  Eocene  deposits  lying  beneath  the  Buhrstone.     The  name  has  recently 
been  restricted  by  Harris  to  the  beds  lying  between  the  Buhrstone  and  the  Matthews  Land- 
ing clays,  and  is  so  employed  here.     The  formation  includes  shallow-water  depositions. 
Lignitic  clay  beds  alternate  with  sands  ;  the  latter  are  often  cross-bedded  ;  huge  bowlders 
or  septaria-like  concretions  are  locally  very  abundant.     Animal  remains  are  scarce  or 
wanting  in  the  deposits  west  of  the  Mississippi ;  but  in  Alabama  and  to  the  northeast,  in 
Maryland  and  Virginia,  they  are  abundant  in  certain  layers.     Where  most  typically  devel- 
oped (in  Alabama)  the  various  subdivisions  have  received  the  following  names  and  estimates 
of  thickness  from  Smith  and  Johnson :    (1)  Nanafalia,  200';  (2)  Bell's  Landing,  140'; 
(3)  Wood's  Bluff,  80'-85';  (4)  Hatchetigbee,  175';  total,  600'. 

The  Pamunkey  formation  (Darton),  i.e.  the  Eocene  deposits  of  Maryland  and  Vir- 
ginia, are  referable  to  the  Bell's  Landing  horizon. 

3.  The  Lower  Claiborne  was  so  designated  by  Harris  to  distinguish  it  from  the  Claiborne 
proper.     It  is  represented  in  South  Carolina,  Georgia,  and  Alabama  by  the  Buhrstone  of 
Tuomey  and  Lyell ;  in  Mississippi  by  the  Siliceous  and  Calcareous  Claiborne  of  Hilgard  ; 
in  Louisiana  by  the  Lower  Claiborne  of  Harris ;  in  Texas  by  the  Timber  Belt  beds  and 
the  Lafayette  beds  in  part,  of  Penrose  ;  in  California  by  part  of  the  Tejon  group  of  Gabb 
and  Whitney.    Near  the  axis  of  the  Mississippi  Embayment  this  group  is  without  marine 
fossils  ;  elsewhere,  especially  in  its  upper  portion,  it  is  often  highly  fossiliferous.     In  Ala- 


CENOZOIC   TIME  —  TERTIARY.  889 

bama  Smith  and  Johnson  have  assigned  the  following  thicknesses  to  its  various  sub- 
divisions: Buhrstone,  300';  Lisbon  beds,  50';  Ostrea  sellceformis  beds,  about  65';  in  all 
about  415'. 

4.  The  Claiborne  was  named  by  Conrad  from  Claiborne,  Ala.     The  typical  develop- 
ment of  this  group  is  of  very  limited  geographical  extent,  being  confined  to  the  drainage  of 
the  Alabama  and  Tombigbee  rivers  (Langdon) ;  but  in  Arkansas  at  White  Bluff  on  the 
Arkansas  River  and  elsewhere,  there  are  marly  sands  with  a  fauna  showing  Jackson  affin- 
ities, though  they  are  at  present  classed  as  uppermost  Claiborne.     The  typical  Claiborne 
bed  is  16'  thick ;  the  White  Bluff  bed  over  it,  20'. 

5.  The  Jackson  beds  were  so  named  by  Conrad  from  typical  exposures  at  Jackson, 
Miss.    They  are  sometimes  improperly  classed  with  the  Vicksburg,  under  the  name  of 
White  Limestone.     They  occur  on  the  Gulf  slope  east  of  the  Sabine  River.    In  Arkansas 
and  probably  in  Mississippi  they  extend  some  distance  up  the  Mississippi  Embayment, 
overlapping  Claiborne  and  Lignitic  beds.     They  are  clayey  and  lignitif  erous  in  this  region ; 
but  to  the  east,  in  Alabama,  become  calcareous  and  constitute  beds  of  impure  limestone. 
Thickness  over  50'. 

6.  The  Vicksburg,  named  by  Conrad  from  typical  exposures  at  Vicksburg,  Miss.     This 
group  is  mainly  composed  of  limestones,  pure  and  impure,  and  like  the  Jackson  is  confined 
to  the  Gulf  slope  east  of  Sabine  River  ;  and  unlike  the  preceding  groups,  it  is  little  influ- 
enced by  the  Mississippi  Embayment.     According  to  Langdon's  figures  its  thickness  varies 
from  150'  to  210'.     The  Eed  Bluff  group  of  Hilgard  is  scarcely  separable  faunally  from  this. 

General  Eemarks.  —  Although  it  has  been  said  that  the  Cretaceous  ( Chico)  and  the 
Eocene  (Tejori)  deposits  west  of  the  Rocky  intergrade  without  a  perceptible  break, 
their  respective  faunas  indicate  that  there  is  a  break  somewhere.  On  the  Atlantic  and 
Gulf  slopes  there  is  abundant  proof  of  a  marked  discordance,  both  faunal  and  stratigraphic, 
between  the  Cretaceous  and  Eocene  Tertiary  series.  In  the  Mississippi  Embayment,  at 
least  in  eastern  Arkansas,  the  earliest  known  Eocene  beds  pass  up  and  over  the  Cretaceous, 
while  in  southwest  Arkansas,  Texas,  Alabama,  and  Georgia,  broad  areas  of  Cretaceous  are 
exposed ;  in  Maryland  and  Virginia,  where  lowest  Eocene  is  wanting,  Lignitic  beds  rest 
upon  the  Cretaceous. 

II.  MIOCENE  AND  PLIOCENE,  OR  NEOCENE  OF  THE  ATLANTIC  AND  GULF 
BORDERS.  — While  dredgings  from  the  Grand  Bank  of  Newfoundland,  as  well 
as  from  St.  George's  Shoal,  off  the  coast  of  Massachusetts,  render  it  probable 
that  later  Tertiary  deposits  exist  beneatn  these  shallow  seas,  the  first  distinct 
exposures  found  on  the  Atlantic  coast  are  those  of  Martha's  Vineyard  at  Gay 
Head  and  Chilmark,  as  recently  proved  through  a  study  of  the  fossils  by 
Dall  (1894).  The  next  is  near  the  village  of  Bridgeport  in  New  Jersey. 
These  exhibit  Miocene  marls  of  black,  yellow,  and  gray  hues,  with  a  thick- 
ness of  from  12  to  15  feet.  The  sands,  clays,  and  marls  from  the  Artesian 
well  at  Atlantic  City  indicate  that  the  thickness  of  the  Miocene  strata  there 
is  not  less  than  700  feet.  These  deposits  are  mainly,  if  not  exclusively,  of 
Upper  or  YorJctown  Miocene  age. 

In  Maryland  the  escarpments  along  the  western  shore  of  Chesapeake  Bay, 
and  along  the  Patuxent  and  Potomac  rivers,  show  Miocene  beds  of  sand  and 
•clay,  rarely  indurated,  and,  at  base,  thick  deposits  of  diatomaceous  earth, 
amounting  in.  all  to  a  thickness  of  400  feet.  In  Virginia  a  similar  series  is 
exhibited  along  the  river  courses';  and  in  the  region  of  Dismal  Swamp 
younger  beds  of  Pliocene  age  are  reported. 


890  HISTORICAL   GEOLOGY. 

In  North  Carolina  these  deposits  are  much  thinner  than  in  Maryland  and 
Virginia,  and  in  South  Carolina  they  usually  occur  in  isolated  basins  or  sinks 
in  the  subjacent  Eocene  or  Cretaceous  strata ;  they  often  show  a  reworking 
or  rearrangement  of  material,  so  that  Miocene,  Pliocene,  and  even  Cretaceous- 
fossils  occur  in  one  and  the  same  bed.  The  component  materials  are  sand,, 
clay,  and  comminuted  shells. 

There  are  deposits  in  Georgia  of  limestone,  buhrstone,  and  conglomerates 
that  belong  to  the  older  Miocene  series,  but  their  geographical  extent  is  not. 
well  determined. 

Florida  presents  the  most  complete  section  of  American  marine  Miocene 
and  Pliocene  formations.  Immediately  above  the  Eocene  along  the  Chatta- 
hoochee  River  occur  beds  of  limestone,  clay,  and  marl,  —  the  Chattahoochee 
group  of  Langdon,  —  having  a  thickness  of  about  200  feet.  Higher  still  are 
the  fossiliferous  Chipola  sands,  succeeded  in  turn  by  the  Alum  Bluff  sands, 
40  feet  thick,  containing  few  organic  remains  save  lignite  and  plants.  Above 
these  occurs  a  gray  marl  having  a  Yorktown  fauna  35  feet  thick.  These 
Miocene  deposits  occupy  much  of  the  northern  portion  of  the  state.  To  the 
south  the  Peace  Creek  lacustrine  deposits  and  Caloosahatchie  beds  of  Plio- 
cene or  Pleistocene  age  are  probably  well  developed,  though  their  exact  limits 
are  not  definitely  determined. 

The  Neocene  beds  of  Mississippi  as  well  as  Alabama  and  Louisiana  — 
Grand  Gulf  group  of  Hilgard  —  contain  but  few  animal  remains,  and  their 
horizon  has  been,  and  still  is  to  some  extent  a  matter  of  dispute ;  but  the 
labors  of  L.  C.  Johnson  and  Langdon  in  southeastern  Mississippi,  southern 
Alabama,  and  northwestern  Florida  tend  to  show  that  they  should  be  corre- 
lated with  the  lower  Miocene  of  the  Floridian  section.  They  are  well  devel- 
oped in  Mississippi,  and  although  concealed  to  the  south,  doubtless  underlie 
the  greater  part  of  the  state  south  of  a  line  roughly  drawn  through  Vicks- 
burg,  Raymond,  Byram,  Brandon,  Raleigh,  and  Waynesboro,  or,  in  other 
words,  south  of  the  Vicksburg  formation.  Below  and  to  the  east  these  beds 
are  clayey,  lignitic,  and  gypsiferous ;  above  and  to  the  west  the  aranaceous 
material  predominates,  and  when  indurated  gives  a  rugged  topography  to- 
the  region  in  which  it  occurs.  No  traces  of  similar  deposits  have  been  found 
in  Tennessee  or  Arkansas  ;  but  in  Louisiana  they  occur  resting  upon  the 
Vicksburg  limestone  and  extending  in  a  southwestern  direction  toward  the 
Sabine  River. 

Certain  deposits  of  clay,  lignite,  and  sandstone  in  Texas  —  the  Lafayette- 
beds  of  Penrose  —  have  been  correlated  with  the  Grand  Gulf  rocks  of  Missis- 
sippi ;  but  the  presence  of  Lower  Claiborne  species  —  although  rare  — 
throughout  much  of  their  vertical  range,  renders  it  quite  probable  that  all 
should  be  referred  to  the  Eocene  period.  To  the  seaward  marine  Neocene 
beds  are  unknown  at  the  surface ;  yet  borings  from  the  Deep  Well  at  Galves- 
ton  show  that  at  no  great  depth  such  deposits  do  occur  with  a  thickness  of 
1500  feet  or  more.  Many  lacustrine  deposits  are  found  at  the  surface  bearing; 
Vertebrate  remains  of  a  late  Tertiary  age. 


CENOZOIC   TIME  —  TERTIAEY.  891 

The  epochs  of  the  marine  Miocene,  as  defined  from  the  formations  of  the  Atlantic  and 
Gulf  borders,  are  as  follows  :  — 

1.  CHATTAHOOCHEE  :  so  named  by  Langdon,  from  typical  exposures  on  Chattahoochee 
River,  southwest  Georgia,  and  northwest  Florida.     Dall  correlates  with  the  Chattahoochee 
deposits  the  Hawthorn  beds  of  central  Florida,  consisting  of  phospbatic  oolyte,  ferruginous 
gravel,  and  green  clays,  the  Orthaulax  bed  and  Tampa  limestone  at  Tampa,  the  Altamaha 
grits  of  Georgia,  and  also  the  "typical  Gfrand  Gulf"  of  southern  Alabama.     The  last- 
named  deposits  are  placed  at  this  horizon  because  they  are  ' '  analogous  to  and  probably 
synchronous"  with  the  Altamaha  grits  of  Georgia,  and  are  overlaid  at  Roberts,  Escambia 
County,  Fla.  (according  to  Smith),  by  a  bed  containing  Chipola  fossils,  as  identified  by 
Dall.    The  Chattahoochee  fauna  is  closely  related  to  the  Miocene  of  West  Indies,  Jamaica, 
Trinidad,  Haiti,  Curac,oa,  Panama,  and  Costa  Rica  (Dall). 

2.  CHIPOLA.  :  distinguished  by  Burns,  and  first  named  by  him  in  manuscript  as  the 
Chipola  formation  from  typical  exposures  on  a  river  by  that  name  in  northwestern 
Florida.    The  lower  member  of  the  group,  the   Chipola  sands,  is  famous  for  its  vast 
number  of  fossil  shells,  nearly  400  species  having  been  found  at  the  type  locality.     This- 
remarkable  faunal  development  is  to  the  Miocene  what  the  Claiborne  fauna  is  to  the 
Eocene  ;  both  occur  in  slightly  ferruginous  sands  about  16'  thick,  both  appear  to  be  very 
limited  in  areal  extent,  and  both  occur  medially  in  their  respective  periods. 

The  fauna  of  the  Alum  Bluff  sands  (Dall)  immediately  overlying  the  fossiliferous 
Chipola  bed  has  not  been  carefully  studied. 

All  these  older  Miocene  deposits  are  characterized  by  a  warm-water  or  subtropical 
fauna  (Dall). 

3.  YORKTOWN  :  named  from  Yorktown,  Va.,  by  Dana  (1863).     It  is  the  time-equiva- 
lent of  the  Chesapeake  group  of  Darton  and  Dall  (1891).     It  includes  the  Miocene  of  the 
Atlantic  slope  as  known  to  geologists  prior  to  1887.     The  section  at  Alum  Bluff  shows 
that  this  group  lies  above  the  Chipola.     It  is  well  developed  in  Duplin  County,  N.  C.,  at 
Yorktown,  and  elsewhere  in  Virginia,  and  along  the  river  courses  in  Maryland.     Calvert 
Cliffs  on  the  west  shore  of  Chesapeake  Bay  exhibit  three  well-defined  fossiliferous  zones, 
named,  in  descending  order,  the  St.  Mary's,  Jones  Wharf,  and  Plum  Point.     Beds  lower 
still  in  the  series  are  found  on  the  eastern  shore  of  Maryland,  and  with  these  in  New  Jersey 
Dall  finds  traces  of  older  Miocene  fossils.     It  has  been  identified  by  its  fossils  on  Martha's 
Vineyard  by  Dall. 

A  modification  of  this  fauna  is  found  in  the  Galveston  Deep  Well,  Tex.,  between 
depths  of  2000'  and  3000'. 

Since  the  publication  of  Gabb's  work  on  the  California  Geological  Survey  the 
Miocene  as  well  as  Pliocene  fossil  remains  of  the  Pacific  slope  have  received  little  attention. 
As  a  rule  the  Miocene  fossils  are  poorly  preserved,  and  are  often  embedded  in  firm 
rock.  Their  general  aspect  indicates  a  horizon  more  nearly  that  of  the  Yorktown  group 
than  that  of  the  older  Miocene. 

In  Georgia  and  Florida,  where  newest  Eocene  and  oldest  Miocene  occur,  there  is 
a  marked  faunal  break  between  the  two,  yet  there  are  several  species  in  common.  In 
Maryland  and  Virginia,  where  Yorktown  Miocene  rests  upon  Lignitic  Eocene,  the  break 
is  complete,  not  one  species  being  found  common  to  the  two.  The  upper,  or  Yorktown, 
Miocene  was  characterized  by  a  fauna  indicative  of  a  temperature  similar  to  that  of  to-day. 

The  Ashley  marl  bed  of  South  Carolina,  containing  phosphatic  nodules  with  fossils- 
in  them,  which  was  referred  by  Tuomey  doubtingly  to  the  Eocene,  affords  Miocene- 
fossils  (1894).  Of  marine  Pliocene,  there  are  the  Floridian  deposits  of  Heilprin  as  modi- 
fied by  Dall  (1892);  the  Pliocene  of  Tuomey  (1848),  excluding  some  Miocene  beds  as; 
determined  by  the  investigations  of  C.  W.  Johnson  and  Dall.  To  this  period  have  been 
referred  the  Orange  sand  group  of  Safford  (1856),  occurring  in  Tennessee,  the  Orange 
sand  of  Hilgard  (1860),  in  Mississippi  and  Tennessee,  the  Orange  sand,  or  Lagrange 


892  HISTORICAL   GEOLOGY. 

•.group,  of  Safford  (1864),  the  Appomattox  of  McGee  (1888), — all  of  one  formation,  and 
now  named  by  agreement  the  Lafayette  j  made  by  Hilgard,  and  in  this  work,  a  formation 
of  the  Glacial  period.  Marine  deposits  of  this  period  are  well  developed  along  the  Caloosa- 
hatchie  River,  south  Florida.  To  the  north,  considerable  areas  are  supposed  to  have  been 
•occupied  by  lakes  having  but  slight  elevations,  and  subject  to  occasional  intrusions  of 
the  sea  with  its  salt-water  fauna ;  hence  the  Peace  Creek  bone  beds  in  Manatee  County, 
and  Alachua  clays,  in  Alachua  County,  are  found  apparently  interstratified  with  marine 
Pliocene  deposits  (Dall,  U.  8.  G.  8.  Bulletin,  No.  84).  The  Mammals  include  a  considerable 
number  of  Eocene,  Quaternary,  and  Pliocene  species,  and  the  beds  are  supposed  to  be 
•Quaternary  in  accumulation. 

Dall  reports  that  the  Miocene  group  of  Gay  Head,  Martha's  Vineyard,  is  overlaid  by 
l^eds  affording  Pliocene  fossils  (1894). 

MIOCENE  AND  PLIOCENE  OF  THE  PACIFIC  COAST. — Along  Carrizo  Creek,  east  of  the 
coastal  range  of  mountains  in  southern  California,  there  is  a  bank  or  terrace,  sometimes 
composed  of  fossil  shells  in  its  upper  part,  that  has  been  referred  to  the  Miocene  Tertiary 
by  Conrad  and  to  the  Pliocene  by  Gabb.  The  sandstones  and  shales  of  the  Santa  Suzanna, 
•Santa  Monica,  and  Santa  Inez  ranges  are  mainly  referable  to  the  Miocene  ;  the  conglomer- 
ates and  sandstones  about  the  base  of  the  San  Gabriel  range  can  only  be  classed  as  Neocene. 
Resting  on  the  granitic  axis  of  Santa  Lucia  Mountains  are  highly  metamorphosed  Neocene 
•(Miocene  ?)  sandstones ;  stratigraphically  above  are  thick  deposits  of  bituminous  shales, 
"which  toward  the  southeast  are  overlaid  by  soft,  sometimes  calcareous,  sandstone,  having 
;a  thickness  of  over  1000',  and  referable  to  the  Miocene  series  on  paleontological  evidence. 
Sandstones  and  bituminous  slates  of  this  age  have  been  described  from  the  Sierra  de 
Salina,  Gavilian,  Santa  Cruz,  and  Mount  Diablo  ranges.  In  the  region  of  Mount  Diablo 
Turner  finds  the  Miocene  series  made  up  of  coarse  gray  sandstone  containing  the 
large  Ostrea  titan,  and  conglomerates  with  pebbles  of  rhyolyte,  quartz,  and  metamorphic 
rock.  The  Pliocene  beds  contain  marine  fossils,  silicified  wood,  hornblende-andesyte  tufa, 
and  pebbles.  North  of  the  Golden  Gate  several  fossiliferous  Miocene  deposits  have  been 
recorded,  but  their  characters  and  limits  are  unknown.  Along  the  foothills  of  the  Sierra 
Nevada,  especially  in  the  vicinity  of  Ocoya  Creek,  there  are  Miocene  beds  of  fine  sand, 
coarse  sand,  conglomerates,  fragments  of  pumicestone,  ferruginous  fossiliferous  gravel, 
and  clay  nodules,  in  all  160'  thick.  Farther  to  the  north,  the  lone  formation  of  Lindgren, 
best  developed  in  Amador  and  Calaveras  counties,  is  composed  of  (1)  100'  of  clay  rock, 
(2)  100'  of  sandstone,  (3)  860'  or  more  of  white  clay  and  sand  beds  containing  coal  seams. 

In  Oregon,  Miocene  sandstones  and  shales  occur  at  Astoria,  and  others,  presumably 
of  the  same  age,  at  Port  Orford,  Cape  Blanco,  and  near  Yaquina  Bay.  They  are  perhaps 
a  continuation  of  the  bituminous  shales  and  sandstones  of  California.  From  1  to  3  miles 
-east  of  Eugene  City,  Dall  has  noted  a  Miocene  sandstone  37'  thick.  Condon  states  that 
the  backbone  of  the  Coast  Range  consists  of  argillaceous  Miocene  shale  similar  to  that  at 
Astoria ;  stratigraphically  above  are  the  fossiliferous  Solen  beds  of  Condon,  also  of 
Miocene  age  ;  on  the  flanks  of  the  highlands  there  are  lacustrine  deposits  containing  some 
Equus  bed  (Quaternary)  fossils. 

In  Washington,  the  Astoria  clay-shales  are  reported  from  near  Bruceport,  and  at  vari- 
ous points  on  Shoal  water  Bay.  Other  outcrops  of  the  same  formation  are  known  from 
Vancouver  Islands  and  Alaska. 

The  Pliocene  Merced  group  of  Lawson  (Bull.  Geol.  Univ.  Cal.,  i.,  142,  1893),  on  the 
coast  of  the  San  Francisco  peninsula,  south  of  the  Golden  Gate,  is  described  as  having  a 
thickness  of  5834'.  A  cliff  consisting  of  the  beds,  720'  high,  extends  from  Lake  Merced, 
near  San  Francisco,  to  Mussel  Rock,  about  8  miles  south  of  Point  Lobos.  The  basal  bed 
contains  some  carbonized  wood  and  leaves.  Some  of  the  fossils  were  described  by  J.  G. 
Cooper  in  1888,  and  a  list  of  others,  determined  by  Dall,  is  given  in  Lawson's  paper. 
Delta  material  in  the  great  valley  of  California  at  San  Benito  also  is  referred  by  him 
to  the  Pliocene. 


CENOZOIC    TIME  —  TERTIARY.  893 

Miocene  and  Pliocene  beds  have  been  identified  in  Alaska,  and  descriptions  and  a  map- 
showing  their  distribution,  by  W.  H.  Pall,  are  contained  in  his  Bulletin  84  of  the  U*  S. 
G.  S.,  1892. 

2.  Lacustrine  Deposits  of  the  Continental  Interior  and  Pacific  Slope. 

I.  EOCENE.  —  The  lacustrine  Eocene  areas  are  confined  mostly  to  the  summit  region 
of  the  Rocky  Mountains  and  its  broad  slopes,  and  are  noted  for  the  abundance  of  fossil 
vertebrates.     The  oldest,  according  to  present  knowledge,  that  of  the  Puerco  basin,  covers 
a  large  area  in  northwestern  New  Mexico,  and  extends  northward  into  Colorado.     The 
beds  rest  on  the  upturned  Laramie,  and  are  overlaid  conformably  by  the  Wasatch  beds. 

The  Wasatch  basin  (W  on  the  map,  Fig.  1468),  also  Lower  Eocene,  lies  to  the  north  of 
the  Uinta  Mountains,  and  east  of  the  Wasatch  range.  Its  original  breadth  was  probably 
nearly  300  miles,  and  the  extreme  length  from  north  to  south  perhaps  500  miles.  The 
thickness  of  the  beds  near  the  Wasatch  range  is  about  4000'.  The  Wasatch  also  occupies 
a  basin  extending  from  New  Mexico  northward,  to  the  Uinta  Mountains  and  the  Big  Horn 
basin  in  Wyoming.  The  beds  also  of  the  Cuchara  basin  of  R.  C.  Hills  are  referred  to  the 
Wasatch  Eocene. 

Two  other  basins,  the  Green  River  and  Wind  River,  are  situated  to  the  north  of  the 
Uinta  Mountains,  and  are  intermediate  in  age  between  the  Wasatch  and  Bridger.  The 
Green  River  basin  is  situated  mostly  within  Wyoming,  and  has  an  area  of  more  than  5000 
square  miles.  The  beds  consist  of  impure  limestone  below,  and  thin  fissile  calcareous  shales 
above,  in  all  3000'  to  4000',  and  are  especially  noted  for  their  fossil  Fishes  and  Insects. 
Fine  views  of  the  bluffs  and  of  the  "  Bad  Lands  "  of  the  Wasatch  are  given  in  King's  40th 
Parallel  Report,  on  plates  13,  14,  15 ;  and  general  views  of  the  Green  River  basin,  in 
•Hayden's  Report  for  1872.  The  Manti  beds  of  Cope  (1880),  occurring  in  Sevier  and  San 
Pete  counties,  Utah,  are  similar  in  character  and  fossils  to  those  of  the  Green  River  basin. 

The  Bridger  basin  of  the  Middle  Eocene  is  situated  between  the  meridians  of  109  p 
W.  and  1101°  W.,  and  for  the  most  part  north  of  the  parallel  of  41°.  Washakie 
basin  of  King  (1878),  which  lies  60  miles  farther  east,  and  the  Huerfano  group  of  R.  C. 
Hills  (1888-1891),  are  of  the  same  age.  The  latter  lies  to  the  east  of  the  Front  Range  in 
Huerfano  and  Las  Animas  counties,  southern  Colorado. 

The  Uinta  lake  basin  (U,  Fig.  1468),  of  the  Upper  Eocene,  lies  wholly  to  the  south  of 
the  Uinta  Mountains,  and  has  now  a  level  of  about  10,000'  above  the  sea.  Its  width  from 
east  to  west  is  over  140  miles. 

The  Amyzon  beds,  referred  to  the  later  part  of  the  Eocene,  occur  in  northeastern 
Nevada,  in  South  Park,  Col.,  and  in  central  Oregon.  They  are  probably  intermediate 
between  the  Uinta  and  White  River  beds. 

The  small  Florissant  basin  is  situated  8000'  up  in  the  mountains  of  southern  Colorado. 
Its  beds  are  largely  made  of  volcanic  earth,  or  tufa,  and  have  become  famous  for  their 
great  numbers  of  fossil  Insects  and  Spiders,  and  also  for  their  Fishes,  and  for  feathers 
and  other  remains  of  Birds,  besides  plant  remains. 

II.  MIOCENE.  — In  the  Miocene  period  the  Eocene  lakes  of  the  Rocky  Mountain  region 
had  mostly  been  drained  through  an  increase  in  the  elevation  of  the  land  or  changes  in  its 
surface  level ;  but  the  mountain  area  still  remained  so  low  that  even  greater  lakes  then 
existed  over  what  are  now  the  eastern  slopes  of  the  mountains.     They  were  situated  in 
the  region  of  the  upper  Missouri,  and  covered  most  of  the  state  of  Nebraska  and  a  portion 
of  Wyoming  and  Colorado,  and  extended  from  Nebraska  southward.     The  area  is  over 
350  miles  in  its  maximum  breadth,  and  has  a  height  at  the  present  time,  through  subse- 
quent elevation,  of  about  6000'  to  the  west  and  3000'  to  the  east. 

The  Earlier  Miocene  is  that  of  the  White  River  group.  Its  oldest  deposits,  the 
Titanotherium  beds  of  Hay  den,  consist  mainly  of  variegated  clays,  together  with  sand- 
stones and  conglomerates,  and  have  a  thickness  of  180'  (J.  B.  Hatcher)  ;  above  are  the 


894 


HISTORICAL   GEOLOGY. 


Oreodon  beds  of  sandstones  and  clays,  often  nodulous,  about  150',  with  100'  of  overlying 
clays  (Wortman)  ;  and  above  these  the  Protoceras  beds,  sandy  below,  but  clayey  above, 
150',  in  all  480'  thick  (Wortman). 

In  the  region  of  these  basins  the  strata,  owing  to  erosion  by  rills  and  streams  from 
occasional  rains,  stand  in  isolated  earthworks  or  embankments,  pyramids  and  spires,  over 
the  great  plain,  looking  like  a  field  of  desolate  ruins,  parched  and  barren  in  the  dry 
-climate.  To  this  region  was  first  applied  the  term  "  Mauvaises  Terres,"  or  Bad  Lands. 

In  Oregon,  on  John  Day  and  Des  Chutes  rivers,  near  120°  W.,  is  another  lake-basin, 
the  John  Day  basin  (D,  Fig.  1468),  hardly  500  square  miles  in  area.  The  Miohippus  beds 
of  Marsh,  the  upper  portion,  have  afforded  remains  of  Miocene  Mammals,  apparently  of 
a  little  later  date  than  the  White  River  beds.  Marsh  correlates  with  the  Oregon  Miohippus 
beds  the  Protoceras  beds  of  Wortman,  stating  that  the  latter  contain  the  Oregon  species 
Miohippus  annectens  Marsh  ;  and  he  further  makes  his  Ammodon  beds  of  the  Miocene  on 
the  Atlantic  border  essentially  of  the  same  horizon. 

The  Loup  Fork  Group,  of  the  Upper  Miocene,  was  so  named  from  a  river  in  Central 
Nebraska.  The  beds  cover  for  the  most  part  the  Nebraska  lake  region  (marked  N  on  the 
map),  and  its  extension  southward  to  Texas,  New  Mexico,  and  Mexico.  King  gives  the 
thickness  in  Wyoming  as  2000'.  To  the  eastward,  on  the  White  River,  it  is  150'.  The 
Deep  Creek  beds  of  Montana,  first  made  known  by  S.  B.  Grinnell  and  E.  S.  Dana  (1876), 
or  the  Ticholeptus  beds  of  Cope,  are  referred  by  W.  B.  Scott  to  the  earlier  part  of  the 
Loup  Fork  epoch.  The  basin  is  situated  near  Camp  Baker,  50  miles  east  of  Helena,  along 


RICHMOND  INFUSORIAL  EARTH. —  a,  Pinnularia  peregrina;  6,  c,  Odontidium  pinnulatum ;  d,  Grammatophora 
marina ;  e,  Spongiolithis  appendiculata ;  /",  Melosira  sulcata  ;  g,  transverse  view,  id.  ;  h,  Actinocyclus  Ehren- 
bergii;  *,  Coscinodiscus  apiculatus ;  j,  Triceratinm  obtusum  ;  Jfc,  Actinoptychus  undulatus  ;  I,  Dictyocha 
crux ;  m,  Dictyocha ;  n,  fragment  of  a  segment  of  Actinoptychus  senarius ;  o,  Navicula ;  p,  fragment  of 
Coscinodiscus  gigas. 


CENOZOIC    TIME  —  TERTIARY. 


895 


Deep  River  Valley  (or  Deep  Creek)  and  other  valleys  of  the  vicinity.  The  beds  are  hard 
•cream-colored  clays,  overlaid  by  loose  beds  of  coarse  and  fine  material  of  the  Loup  Fork 
horizon.  Cope's  Ticholeptus  beds  of  Cotton  wood  Creek,  in  Oregon,  according  to  Scott, 
are  probably  of  the  Loup  Fork  horizon ;  but  those  of  western  Nebraska  he  refers  to  the 
White  River  group. 

The  Pah-  Ute  Lake  of  King,  named  from  a  mountain  ridge  in  Nevada,  was  described 
by  him  as  extending  from  the  Columbia  River,  through  Oregon  and  Nevada,  into  Cali- 
fornia— an  improbable  range  for  one  lake.  He  named  its  beds  the  Truckee  Miocene. 
They  include,  in  Nevada,  sands,  grits,  volcanic  tufa,  and  infusorial  deposits,  the  last 
250'  to  300'  thick. 

Diller  reports  the  Upper  Sacramento  Valley  as  the  area  of  a  great  Miocene  lake, 
'covering  part  of  the  northern  end  of  the  Sierra  Nevada. 

III.  PLIOCENE. — The  Blanco  beds  of  Cummins  and  Cope,  on  the  Staked  Plains  of 
western  Texas,  consist  at  Blanco  Canon  of  beds  of  clays  and  sands,  in  all  150'  to  200' 
•thick.  The  underlying  beds  are  referred  to  the  Triassic.  The  beds  extend  northward 
•beyond  Red  River. 

LIFE. 

PLANTS.  —  1.  Protophytes.  —  About  100  species  of  Diatoms  have  been 
described  by  Ehrenberg  and  Bailey,  from  the  Infusorial  stratum  of  Eich- 
mond,  besides  a  few  Polycystines  and  many  sponge-spicules.  Fig.  1469  repre- 
sents a  portion  of  the  Eichmond  earth,  as  it  appeared  in  the  field  view  of 
Ehrenberg's  microscope.  This  is  an  example  of  one  of  the  many  Infusorial 
•earths  of  the  era. 

2.   Angiosperms,  Conifers,  Palms.  —  The  lignitic  beds  in  the  lower  part 


1470,  Quercus  myrtifolia  (?);  1471,  Cinnamomum  Mississippiense ;  1472,  Calamopsia  Danse;  1478,  Fagus 
ferruginea  (?);  1474,  Carpolithes  irregularia. 


896 


HISTORICAL   GEOLOGY. 


1475. 


of  the  Eocene  of  Mississippi,  Arkansas,  and  elsewhere,  have  afforded  large- 
numbers  of  leaves  of  plants;  others  have  been  obtained,  together  with  a 
variety  of  nuts,  from  the  bed  of  lignite  at  Brandon,  Vt. 

The  plants  of  these  beds,  some  of  which  are  here  represented,  are  closely 
related  to  those  of  the  present  era. 

Fig.  1470  represents  an  oak  leaf  (Quercus  myrtifolia)  from  Somerville, 
Tenn.,  the  Lagrange  group  of  Safford;  Fig.  1471,  leaf 
of  a  cinnamon  (Cinnamomum  Mississippiense) ,  from 
Mississippi,  at  Winston;  Fig.  1472,  a  palm  (Cala- 
mopsis  Dance  Lsqx.),  from  Mississippi,  in  Tippah, 
Lafayette,  Calhoun ;  Fig.  1473,  nut  of  a  beach  (Fagus 
ferruginea  (?)),  from  the  Lagrange  group  of  Tennes- 
see; Fig.  1474,  fruit  (Carpolithes  irregularis  Lsqx.), 
from  the  Brandon  Lignite  bed;  Fig.  1475  (Carpo- 
lithes Brandonensis  Lsqx.),  the  most  abundant  of  the 
Brandon  nuts,  natural  size.  The  kind  of  plant  pro- 
ducing these  two  fruits  is  undetermined.  Among 
the  other  Brandon  fruits,  Lesquereux  recognized  the 
Carpolithes  Brandonesis.  genera  Qarya,  Fagus,  AristolocMa,  Sapindus,  Cinna- 
momum, Illicium,  Carpinus,  and  Nyssa.  (Am.  Jour.  Sc.,  xxxii.,  355,  1861.) 

ANIMALS.  —  Invertebrates.  —  In  the  Eocene,  among  Protozoans,  Rhizo- 
pods  are  very  numerous  in  some  of  the  beds.  The  coin-shaped  fossils, 
Orbitoides,  resembling  Nummulites  in  form,  abound  in  the  Vicksburg  beds, 
and  the  rock  is  often  called  the  Orbitoides  limestone;  the  common  species, 
0.  Mantelli,  is  represented  in  Fig.  1494. 

Midway.  —  Characteristic  species  of  the  Midway  group  are  represented 
in  Figs.  1476-1478 ;  of  the  Lignitic  group,  in  Figs.  1479-1481 ;  and  Eocene 
of  the  Lower  Claiborne,  in  Figs.  1482-1484,  1487, 1488 ;  of  the  Upper  Clai- 
borne,  in  Figs.  1485, 1486, 1489 ;  of  the  Vicksburg,  in  Figs.  1490-1496 ;  of  the 
Miocene,  in  Figs.  1497-1507 ;  of  the  Pliocene,  in  Figs.  1508-1510. 


1476 


1476-1478. 

1477 


1478- 


EOCENE,  MIDWAY  GBOTTP.  —  Fig.  1476,  Enclimatocenas  Ulrichi ;  1477,  Volatilities  rugatus ;  1478,  V.  limopsis. 
Fig.  1476,  C.  A.  White ;  1477, 1478,  Harris. 


CENOZOIC   TIME  —  TERTIARY. 


897 


1479. 


1480. 


LIGNITIC  GROUP. —Fig.  1479,  Ostrea  compressirostra  (x?) ;    1480,  Dosiniopsis  lenticularis,  var.  Meekii.     Fig. 

1479,  Say ;  1480,  Conrad. 


1481-1486. 


1483 


1484 


1482 


LIGNITIC.  —  Fig.  1481,  Venericardia  planicosta  (x  $).  LOWER  CLAIBORNE.  —  Fig.  1482,  Ostrea  selteformis  ;  1483, 
Pteropsis  Conradi;  1484,  Turritella  nasuta.  UPPER  CLAIBORNE.  —  Fig.  1485,  Crassatella  alta ;  1486, 
Turritella  carinata.  Figs.  1481-1483,  1485,  1486,  Meek ;  1484,  Harris. 


1487 


1489 


LOWER  CLAIBORNE.  —  Fig.  1487,  Belosepia  ungula;   1488,  Mesalia  Claibornensia.     UPPER  CLAIBORNE.  —  Fig. 
1489,  Caricella  Claibornensis.     Harris. 

DANA'S  MANUAL  —  57 


898 


HISTORICAL  GEOLOGY. 
1490-1496. 


1498 


EOCENE.  —  Vicksburg  group.  —  Fig.  1490,  Pecten  Poulsoni ;  o,  section  of  same ;  1491,  Mortonia  Rogers! ;  1492, 
Ostrea  Georgiana  (x$),  Vicksburg  (?)  ;  1493,  Area  Mississippiensis ;  1494,  Orbitoides  Mantelli;  1495,  Lyria 
costata ;  1496,  Dentalium  Mississippiense.  Figs.  1490-1492,  1494,  Meek ;  1493,  1495,  1496,  Conrad. 


1497 


1497-1499. 


1-198 


1499 


MIOCENE.  —  CJiattahoochee  group.  —  Fig.  1497,  Turritella    Tampae  (x  f) ;    1498,    Pyrazisinus  campanulatus ; 
1499,  Cerithium  Hillsboroense.     From  Ball. 


CENOZOIC   TIME  —  TERTIARY. 


899 


1600 


1602 


MIOCENE.  —  Chipola  group.— Fig.  1500,  Orthaulax  Gabbi ;  1501,  Turritella  subgrundifera(x  §) ;  1502,  S  trombus 

Aldrichl.    From  Ball. 


1503-1505. 


1503 


1504 


MIOCENE.  ~  Yorktown  group.  —  Fig.  1503,  Pecten  Jeffersonius  (x  |);  1504,  Ecphora  quadricostata  (x  |);  1505, 

Striarca  centenaria.    T.  Say,  1824. 


900 


HISTORICAL  GEOLOGY. 


1506 


1506,  1507. 

150T 


1506  a 


MIOCENE.  —  Figs.  1506,  a,  Crepidula  costata ;  150T,  Cyprsea  Carolinensis.    Meek. 


1508 


PLIOCENE.  —  Floridian  group.  —Fig.  1508,  Area  crassicosta ;  1509,  Venus  rugatina (x  £);  1510,  Arcoptera avicu- 

Iseformis  (x  £).     Original. 

Insects.  —  The  Insects  of  the  Florissant  basin,  described  by  Scudder, 
include  species  of  all  the  grand  divisions ;  and  hundreds  of  some  of  them. 
The  number,  thus  far  made  out,  according  to  this  author,  is  of  Orthopters, 
24 ;  Neuropters,  57 ;  Hemipters,  220 ;  Coleopters,  over  400,  of  which  116  are 


1511. 


1512. 


INSECTS.  —  Fig.  1511,  Prodryas  Persephone ;  1512,  Tipula  Carolinse.    Scudder. 

Rhynchophora ;  Dipters,  250 ;  Lepidopters,  9 ;  Hymenopters,  about  235 
species.  Of  the  Dipters,  51  are  Tipulidse,  and  one  of  these,  two  thirds  of  an 
inch  in  length,  is  represented  in  Fig.  1512,  and  one  of  the  Butterflies,  in  Fig. 


CEXOZOIC    TIME TERTIARY. 


901 


1511.  Besides  these,  Scudder  has  made  out  31  species  of  Arachnids  or 
Spiders.  He  states  that  about  a  fourth  of  all  the  species  at  Florissant  are ' 
Ants  (Formicidae),  and  that  by  1885  more  than  4000  specimens  of  Ants  had 
been  brought  from  the  beds.  Of  Aphides,  or  Plant-lice,  an  eighth  of  an  inch 
long,  or  less,  he  has  collected  over  100  specimens,  representing  32  species, 
and  all  but  one  showing  well  the  wings.  Two  other  localities,  affording 
similar  species,  one  on  the  crest  of  the  Roan  Mountains  in  western  Colorado, 
and  the  second  on  the  lower  part  of  White  River,  at  the  Utah  line,  are 
supposed  to  be  at  least  as  rich  as  Florissant. 

Eocene  Vertebrates.  1.  Fishes.  —  The  remains  of  Ganoid  fishes  (genera 
Lepidosteus,  Amia),  and  Teleosts,  of  the  Perch,  Herring,  and  other  families, 
are  abundant  in  the  Green  River  shales,  along  with  remains  of  Plants  and 
Insects.  The  marine  Tertiary  beds  of  the  Gulf  and  Atlantic  borders,  and 
especially  of  the  Eocene,  contain,  in  many  places,  the  teeth  of  Sharks  in  great 
numbers  ;  three  kinds  are  represented  in  the  accompanying  figures.  Some 
of  the  triangular  teeth  of  Carcharodon  megalodon  Ag.  (resembling  Fig.  1513), 
are  six  inches  broad  at  base  and  six  and  a  half  long. 


1513-1516. 


1514 


1516 


TEETH  OF  SHARKS.— Fig.  1513,  Carcharodon  angustidens  ;  1514,  Lamna  elegans ;  1515,  Notidanus  primigenius. 
TESTUDINATE.  —  Fig.  1516,  Testudo  brontops  (x  Tz)-     Figs.  1513-1515,  Agassiz ;  1516,  Marsh. 

2.  Reptiles.  — The  Tertiary  Reptiles  include  species  of  Crocodiles,  among 
them,  Crocodilus  Elliotti  Leidy,  from  South  Carolina,  and  C.  Squankensis  of 
Marsh,  from  New  Jersey ;  of  Snakes,  of  the  genus  Dinophis  Marsh,  from 
New  Jersey,  and  of  Boavus  and  Lithophis,  from  Fort  Bridger,  about  20  feet 
long;  of  Turtles,  of  the  genera  Testudo,  Emys,  etc.,  from  the  Atlantic  border 
and  the  Rocky  Mountain  region.  Fig.  1516  represents  one  of  the  largest  of 


902  HISTORICAL   GEOLOGY. 

American  Turtles,  from  the  Lower  Miocene,  or  White  River  beds,  of  Dakota, 
Testudo  brontops  of  Marsh,  which  had  a  length  of  about  two  and  two  thirds 
feet.  The  Puerco  beds  have  afforded  a  species  of  Champsosaurus  (C.  Sapo- 
nensis  of  Cope),  a  Laramie  genus.  A  very  small  species  of  Crocodile  has 
been  reported  from  the  White  Eiver  beds. 

3.  Birds.  —  The  Eocene  and  Miocene  have  afforded  remains  of  species 
related   to   Waders,  an   Owl,  Bubo   leptosteus  of  Marsh,   a   bird  near   the 
Woodpeckers,  some  web-footed  species  allied  to  the  Gannet ;  and  the  Mio- 
cene, remains  of  a  large  Eagle,  a  Cormorant,  and  other  birds.     The  Diatryma 
yigantea  of  Cope,  from  the  early  Eocene  of  New  Mexico,  was  larger  than  the 
Ostrich.      The  Barornis  regens  of  Marsh,  from   the  Upper  marl  beds  of 
Squankum,  N.  J.,  of  the  Eocene,  had  about  the  size  and  many  of  the  charac- 
ters of  the  Ostrich.     From  the  Florissant  beds  have  been  obtained  a  Plover 
and  other  species. 

4.  Mammals.  —  The   sea-border   Tertiary  of  the  continent   has  afforded 
remains  of  but  few  Mammals ;  for  seashores  are  not  their  ordinary  resort 
except  for  aquatic  kinds.     The  regions  of  the  great  lakes  over  the  Rocky 
Mountain  area,  on  the  contrary,  have  been  found  to  be  literally  Tertiary 
burial-grounds.     They  bear  evidence  that  Mammals  in  great  numbers,  and 
of  several  successions  of  faunas,  lived  and  died  about  these  lakes,  and  by 
lacustrine  agencies  were  buried. 

These  ancient  bone-beds  remained  almost  unknown  to  science  until  the 
year  1847 ;  and  now,  through  the  labors  of  explorers,  and  the  works  of 
Leidy,  followed  by  the  memoirs  of  Marsh,  Cope,  Scott,  Osborn,  and  others, 
the  number  of  known  species  far  exceeds  that  of  existing  North  American 
Mammals.  These  Mammals  are,  with  rare  exceptions,  of  the  ordinary  or 
placental  type.  The  Marsupials,  as  in  earlier  time,  were  small  species,  re- 
lated to  the  Opossums ;  and  their  remains  are  known  from  the  Early  Eocene 
onward. 

Eocene.  —  The  Eocene  species  comprise  Herbivorous,  or  Ungulate,  Car- 
nivorous, Insectivorous,  and  Rodent  species,  and  also  Quadrumana;  and 
before  the  close  of  the  period,  Cetaceans,  or  Whales.  The  remains  of  Ungu- 
lates are  most  abundant,  because  such  species  frequent  lake  borders.  They 
are  related  to  the  modern  Tapir,  Wild  Boar,  and  Rhinoceros,  yet  only  in 
a  very  general  way,  as  these  special  types  belong  to  a  later  period.  The 
earliest  of  the  Eocene  species  are  remarkable  for  their  prototype  or  primi- 
tive characteristics :  (a)  the  legs  being  approximately  equal ;  (6)  the  feet 
five-toed  and  of  typical  form,  the  five  toes  similar,  with  the  third  or  middle 
toe  a  little  the  longest ;  (c)  the  carpal  bones  and  the  tarsal  in  vertical  series 
with  the  following  bones  of  the  foot;  (d)  the  teeth  of  the  typical  number, 
44,  —  that  is,  11  in  either  ramus  of  each  jaw,  —  the  11  including  3  incisors, 
1  canine,  4  premolars,  and  3  molars ;  (e)  the  molars  of  simple  form,  being 
usually  tritubercular  at  summit,  or  trigonodont;  (/)  the  head  without 
armature  of  horns  or  tusks. 


CENOZOIC    TIME  —  TERTIARY. 


903 


Moreover,  the  types  are  generally  comprehensive  or  intermediate  kinds. 
The  flesh-eaters  are  intermediate  in  their  teeth  and  other  characters  between 
Carnivores  and  Insectivores,  and  have  been  referred  by  Cope  to  a  separate 
group  named  Creodonts,  from  the  Greek  foi flesh  and  tooth.  Another  group 
has  some  of  the  features  of  the  Tillodonts,  Kodents,  and  Ungulates;  and 
the  Ungulates  also  have  some  of  the  characteristics  of  Carnivores  or 
Quadrumana. 

The  prototypic  features  are  presented  by  species  of  the  genera  Phena- 
codus, Coryphodon,  and  many  others.  They  are  well  illustrated,  as  pointed 
out  by  Cope,  in  the  Phenacodus  primcevus,  described  by  him  from  a  speci- 
men found  in  the  Wasatch  beds  (Fig.  1517).  Besides  the  primitive  features 
of  44  teeth,  of  five  similar  toes  to  both  fore  and  hind  feet,  of  the  carpal 
in  series  with  the  digits  (Figs.  1517  a,  6),  the  feet  were  probably  planti- 
grade, the  foot  striking  the  ground  with  the  whole  sole,  instead  of  being 

1517. 


MAMMAL.  —  Phenacodus  primajvu 


Cope. 


raised  on  the  toes  (digitigrade).  The  animal  is  supposed  to  have  been 
omnivorous,  from  its  teeth.  The  length  of  the  body  was  about  four  feet. 
The  Creodonts  (prototypic  Carnivores)  of  the  Puerco  beds  also  are  described 
by  Cope  as  plantigrade  species. 

These  characters  are  also  well  exhibited,  as  shown  by  Marsh,  in  species 
of  Coryphodon  from  the  Wasatch  group.  A  restoration  of  Coryphodon 
hamatus  of  Marsh  is  represented  in  Fig.  1518,  and  the  fore  feet  and  hind 
feet  in  Figs.  1518  a,  6.  The  length  of  the  body  was  six  feet.  The  special 
prototypic  features  of  the  feet  and  limbs  are  manifest,  after  the  above  state- 
ments, without  special  remarks.  The  animal  was  digitigrade,  and  had 
short,  nearly  equal  toes,  a  type  of  foot  which  is  represented  also  in  the 
modern  Elephant. 

An  early  genus  in  the  line  of  the  Tapir  is  Systemodon  of  Cope,  represented 
by  S.  tapirinus  from  the  Wasatch.  Besides  other  primitive  features,  it  has 
the  teeth  in  a  continuous  series,  there  being  no  interval  (diastema)  between 
the  canines  and  the  premolars. 


904 


HISTORICAL  GEOLOGY. 


The  Tillodonts  of  Marsh,  which   range  from  the  Puerco  through  the 
Bridger  Eocene,  fail  of  prototypic  characters  in  having  less  than  the  normal 


1518. 


Fig.  1518,  Restoration  of  Coryphodon  hamatus  (x  5^)  ;  a,  fore  foot;  6,  hind  foot  (x  £).    Marsh. 


number  of  incisors,  with  one  of  the  pairs  much  elongated  like  those  of  a 
Beaver  and  other  Rodents,  as  shown  in  the  figures  of  Tillotherium  fodiens  of 
Marsh.  The  name,  from  TiAAo>,  bite,  alludes  to  the  long  incisors.  Psitta- 


1519-1523. 


1520 


1519 


Figs.  1519,  Tillotherium  fodiens,  top  view,  with  form  of  brain  cavity  (x  £) ;  1520,  same,  skull  and  lower  jaw ;  1521 
a,  6,  same,  ungual  phalanx  or  claw,  front  and  side  view ;  1522,  T.  latidens,  last  upper  molar  (x  f) ;  1523, 
Anchippodus  minor,  lower  molar  (x  |).  All  from  Marsh. 

cotherium  of  Cope  is  a  genus  of  the  group  from  the  Puerco  beds ;  Anchippodus 
of  Leidy,  from  the  Bridger  group  and  the  New  Jersey  Eocene ;  and  Tillo- 


CENOZOIC    TIME  —  TERTIARY. 


905 


1527 


therium  and  Stylinodon  of  Marsh,  from  the  Bridger  beds.  Figs.  1519-1521 
are  of  Tillotherium  fodiens;  1522,  of  T.  latidens;  and  1523,  of  Anchippodus 
from  Marsh. 

Examples  of  later  specializations  are  here  illustrated  (Figs.  1524-1527),  in 
Tapir-like  species  ]  of  the  genera  Eohippus  and  Orohippus  of  Marsh,  the  former 
from  the  Wasatch  beds,  and  the  latter  from  the  Bridger.  In  Eohippus  the 
fore  feet  (Fig.  1524)  have  all 
the  five  toes  represented,  but  the 
first  toe  is  already  reduced  to  a 
"  splint-bone  "  in  its  metacarpal,  1525 

while  the  hind  feet  (Fig.  1525) 
have  lost  wholly  the  first  toe 
with  the  metatarsal  above,  and 
the  fifth  toe  is  reduced  to  a  splint- 
bone.  In  the  later  Orohippus 
the  first  toe  of  the  fore  foot  with 
its  metacarpal  (Fig.  1526) 


1524-1527. 


1526 


8 


Fig.  1524,  Eohippus  pernix,  left  fore  foot ;  1525,  id.  left  hind 
foot ;  1526,  Orohippus  agilis,  fore  foot ;  1527,  id.  hind 
foot  (all  x  |).  Marsh. 


s 

wholly  wanting,  and  the  first 
and  fifth  of  the  hind  foot  (Fig. 
1527)  are  wanting.  Fig.  1526 
affords  an  illustration  also  of  the 
change  in  the  relative  positions 
of  the  carpals  of  most  Mammals 
(and  also  usually  of  the  tarsals)  from  that  of  vertical  series  (the  prototypic 
position)  to  that  in  which  the  bones  alternate  with  one  another  (Fig.  1526), 
so  as  to  give  the  joint  greater  strength  and  safety.  This  change,  with  others 
of  like  import,  began  even  in  the  Eocene.  In  addition,  the  metacarpals  are 
much  elongated. 

1528. 


Tapirus  Indicus,  the  modern  Malayan  Tapir. 

1  On  account  of  the  frequent  references  in  the  remarks  on  Tertiary  Mammals  to  the 
Tapir,  a  figure  of  a  modern  species  is  here  introduced.  It  shows  its  general  form,  short 
legs,  and  elongate  nose. 


906 


HISTORICAL   GEOLOGY. 


From  the  Puerco  and  Wasatch  beds  come  the  earliest  of  the  Quadrumana. 
Fig.  1529  represents  the  skull  of  one  of  the  species,  Anaptomorphus  homun- 
culus  Cope,  from  the  Wasatch  beds  of  the  Big  Horn  Basin,  of  Wyoming. 


1629. 


Anaptomorphus  homunculus ;  a,  cranium,  from  above  ;  6,  same,  from  below,  enlarged.    Cope. 

Other  Wasatch  species  include  Creodonts  of  several  genera,  Insectivores. 
and  the  earliest  of  true  Kodents.  There  were  also  in  the  Wasatch  beds,  and 
others  equivalent,  the  first  of  Artiodactyl  Ungulates,  the  4-toed  Pantolestes 
brachystomus  of  Cope,  and  Homacodon  prisons  of  Marsh ;  named  Artiodactyls 
(and  also  Paridigitates)  because  the  four  toes  are  in  pairs,  the  third  and  fourth 
being  equal,  and  also  the  second  and  fifth  if  present.  Examples  are  shown 
in  Fig.  1538.  The  two  pairs  are  present  in  the  Hog,  Hippopotamus,  etc. ;  the 

1530. 


Eestoration  of  Tinoceras  ingens  of  Marsh  (x  5^). 


CENOZOIC   TIME  —  TERTIARY. 


907 


1531. 


single  pair  (often  with  rudiments  of  the  other),  in  the  Cainel,  Stag,  Ox,  etc. 
Another  Artiodactyl  of  the  same  horizon  is  the  Eoliyus  distans  of  Marsh, 
having  Suilline  or  hog-like  characteristics. 

The  Bridger  Eocene  is  remarkable  for  the  remains  of  Dinocerata,  animals 
of  Elephantine  dimensions,  having  elongate  canines,  and  two  or  three  pairs  of 
bony  prominences  or  horns  on  the  head.  Fig.  1530  represents  the  Tinoceras 
ingens  of  Marsh,  an  animal  12  feet  in  length.  They  were  successors  to  the 
Coryphodons  of  the  Wasatch.  The  prominences  referred  to  are  situated 
severally  on  the  snout,  the  cheeks,  and  the  forehead.  Marsh  observes 
that  part,  if  not  all  of  them,  were  horn-cores  or  bases  of  horns ;  and  that 
those  that  were  not  so  must  have  been  covered  with  the  hide,  as  in  the  Giraffe. 
While  thus  armed  to  excess,  and  probably  of  great  strength,  the  very  small 
brain  shows  that  they  were  extremely  low  in  intelligence.  The  earliest 
species  are :  Tinoceras  anceps  of  Marsh,  described  in  October,  1872  (his 
Titanotherium  anceps  of  1871,  found  in  1870)  ;  Uintatherium  robustum 
of  Leidy,  August,  1872;  and  Tinoceras  grandis  and  Dinoceras  mirabilis 
of  Marsh,  October,  1872. 
Uintatherium  Leidyanum 
of  Osborn  (1878, 1881)  has 
very  prominent  horn- cores 
and  is  from  Dry  Creek, 
Wyoming.  Uintatherium 
has  36  teeth,  Dinoceras 
and  Tinoceras  34. 

The  Bridger  beds  have 
afforded,  among  species 
related  to  the  Tapir,  the 
genus  Helaletes  of  Marsh, 
having  the  teeth  44  in 
number  and  in  contact, 
which  are  prototypic  char- 
acters: also  species  of  Hyrachyus  and  Palceosyops  of  Leidy,  which  are  es- 
pecially common  in  the  beds.  Fig.  1531  is  a  restoration,  by  C.  Earle,  of 
Palceosyops  paludosus  of  Leidy,  an  animal  about  six  feet  in  length. 

There  are  also  in  the  Bridger  beds  remains  of  Quadrumana,  Creodonts, 
and  Bats,  as  well  as  Eodents  and  Insectivores. 

The  Uinta  group,  the  last  division  of  the  Eocene,  has  afforded  new  Tapir- 
like  species  of  the  genus  Diplacodon  of  Marsh,  related  to  Palceosyops  of  the 
Bridger  group  and  to  the  Titanotheres  of  the  Miocene ;  species  of  Amynodon 
of  Marsh,  related  to  the  Rhinoceros ;  the  Epiliippus  gracilis  of  Marsh,  an 
early  form  of  the  Horse ;  also  the  earliest  of  the  Camel  group,  Leptotragulus 
of  Scott  and  Osborn;  and  of  the  Oreodonts,  Protoreodon;  a  single  genus  of 
Creodonts,  besides  many  other  kinds. 

The  sea-border  Jackson  beds  of  Mississippi,  Alabama,  Georgia,  and  South 
Carolina  have  afforded  bones  of  two  whale-like  Mammals  of  the  genus 


Restoration  of  Palaeosyops  paludosus  (x  5^)  by  C.  Earle,  1892. 


908 


HISTORICAL   GEOLOGY. 


1532. 


Zeuglodon,  one  of  which,  Z.  cetoides,  was  nearly  70  feet  long.      One  nearly 

perfect  skeleton  was  found  in  place  by  S.  B.  Buckley  in  Clark  County,  Ala., 

about  100  miles  north  of  Mobile,  having  the 
length  here  stated.  Vertebrae  were  so  abun- 
dant, on  the  first  discovery,  in  some  places  that 
many  of  these  Eocene  whales  must  have  been 
stranded  together,  in  a  common  catastrophe, 
on  the  northern  borders  of  the  Mexican  Gulf, 
—  possibly  through  a  series  of  earthquake  waves 
of  great  violence ;  or,  by  an  elevation  along  the 
sea  limit  that  made  a  confined  basin  of  the 
border  region,  which  the  hot  sun  rendered  de- 
structive alike  to  Zeuglodons  and  their  game ; 
or,  by  an  unusual  retreat  of  the  tide,  which  left 
them  dry  and  floundering  for  many  hours  under 
a  tropical  sun.  The  Zeuglodon  is  the  Basilosau- 
rus  of  Harlan  (1834),  the  Zeuglodon  of  Owen. 
Some  of  the  dorsal  vertebrae  have  a  length  of  a 
foot  and  a  half,  and  a  diameter  of  a  foot ;  and 
a  rib,  a  length  of  nearly  six  feet.  Fig.  1532 
represents  one  of  the  molar  teeth,  the  yoke-like 
form  of  which  suggested  the  name  Zeuglodon, 

from  £evy\-q,  yoke,  and  oSovs,  tooth.     Some  of  these  teeth  had  a  longer  diameter 

of  four  and  a  half  inches. 

MIOCENE.  —  The  Miocene  Ungulates  were  of  different  species  from  those 

of  the  Eocene,  and  mostly  of  different  genera. 


Tooth  of  Zeuglodon  cetoides  (x  §).  D. 


1533. 


Titanotherium  giganteum  of  Leidy  (x 


Restoration  by  Scott  and  Osborn. 


In  the  earliest  of  the  White  River  group,  the  Titanotherium  '  beds,  the 
species  include  the  gigantic  Titanotheres  ;  new  Horses  of  the  genus  Mesohip- 


CENOZOIC   TIME  —  TERTIARY.  909 

pus;  several  new  genera  of  the  Hog  family,  among  them  species  of  Elothe- 
rium  as  large  as  a  Rhinoceros. 

The  Titanotherium  giganteum  of  Leidy  (1852)  is  one  of  the  earliest  species 
discovered  in  the  White  River  region.  The  restoration,  Fig.  1533,  -j^  the 
natural  size,  is  by  Scott  and  Osborn.  The  length  was  over  13  feet. 

1534. 


Restoration  of  Brontops  robustus  (x^V).    Marsh. 

Fig.  1534  represents  a  restoration,  -^  natural  size,  of  another  of  these 
Titanotheres,  the  Brontops  robustus  of  Marsh.  The  length  of  body  was 
nearly  12  feet. 

1535. 


Elotherium  crassum  of  Marsh  (x  3^). 


A  restoration  of  one  of  the  Artiodactyl  Ungulates  is  shown  in  Fig.  1535, 
representing  a  large  species  of  Elotherium,  E.  crassum  of  Marsh.  Its 
length  was  about  seven  feet.  Its  remains  occur  in  Colorado  and  South 
Dakota. 


910 


HISTORICAL   GEOLOGY. 


Above  the  Titanotherium  beds  lie  the  Oreodon  beds,  so  named  from  a 
characteristic  Artiodactyl,  between  the  Hog  and  Deer  in  structure.  Fig. 
1536  represents,  natural  size,  the  skull  of  the  species,  Oreodon  gracilis  of 
Leidy. 

The  Oreodon  beds  have  afforded,  besides  species  of  several  genera  occurring 
in  the  Titanotherium  beds,  remains  of  Tapir-like  Ungulates  of  the  genus 

1536. 


Oreodon  gracilis.    From  Leidy. 

Protapirus ;  also  others  related  to  the  Khinoceros,  teeth  from  one  of 
which,  of  the  genus  Hyracodon  (H.  Nebrascensis  of  Leidy),  are  shown  in 
Fig.  1537. 

There  were  also  species  related  to  the  Camel;  the  earliest  of  true 
Carnivores ;  the  earliest  known  of  Bats ;  of  Squirrels  of  the  modern  genus 
Sciurus,  with  many  other  Kodents ;  and  Marsupials  of  the  modern  genus 
Didelphys,  or  that  to  which  the  Opossum  belongs. 

1537. 


Teeth  of  Hyracodon  Nebrascensis.     Leidy. 

The  following  is  a  restoration,  y1^  the  natural  size,  of  Poebrotherium 
labiatum  of  Cope,  by  W.  B.  Scott,  a  species  of  the  Camel  family,  near  the 
Llama  in  its  proportions.  It  is  a  fine  example  of  a  two-hoofed  Artiodactyl. 
Its  characteristics  will  be  understood  after  a  comparison  of  the  feet  with 
those  of  Phenacodus,  Fig.  1517.  The  foot  in  Fig.  1538  includes  the  part 


CENOZOIC   TIME  —  TERTIARY. 


911 


of  the  leg  from  /  to  t.  Moreover,  the  upper  ends  of  the  tibia  and  fibula  are 
soldered  into  one  bone.  In  many  species  of  Artiodactyls  the  soldering  is  so 
complete  that  no  suture  is  left  to  indicate  it.  This  addition  to  the  length 
of  the  legs,  by  putting  the  foot  vertical  on  its  toes  and  elongating  the  foot 


1538. 


a      f  a 


ABTIODACTYL  UNGTTLATB.— Fig. 


Poebrotherium  labiatum,  restoration  (x  ^) ;  a,  b,   same,  feet,  less 
reduced.     Scott. 


(especially  the  metatarsal  and  metacarpal  bones),  was  of  great  advantage  to 
the  running  animal ;  for  it  served,  as  also  in  the  Horse,  to  give  a  propor- 
tional increase  of  speed,  other  things  equal. 

The  Fauna  comprised  also  several  Insectivores ;  also  Beavers,  among 
Rodents,  as  the  Palceocastor  Nebrascensis  Leidy,  besides  other  species. 

The  Protoceras  beds  of  Wortman,  making  the  upper  part  of  the  White 
River  group,  are  characterized  by  various  Artiodactyls  related  to  the  Camel, 
Deer,  and  Hog,  and  the  remarkable  Protoceras  of  Marsh,  which  has  long 
canines  and  horn-cores,  the  fore  feet  4-toed,  while  the  hind  feet  are  2-toed ; 
also  others  related  to  the  Tapir  and  Rhinoceros,  and  various  Carnivores  and 
other  species. 

The  John  Day  beds  of  Oregon  are  characterized  by  the  genera  Mioliippus, 
Diceratherium,  Thinohyus,  Poebrotherium,  Eporeodon,  Elotherium,  various 
Eodents  and  Carnivores  of  the  genera  Cynodon,  Temnocyon,  Dinictis,  and 
others. 

In  the  Deep  River  beds  of  the  Upper  Miocene  occur  the  first  known  of 
Mastodons  (M.  proavus  of  Cope),  Rhinoceroses  of  the  genus  Aplielops,  several 
genera  of  the  Horse  type,  Mioliippus,  Desmatippus,  Anchitherium,  Proto- 
hippus. 

The  Loup  Fork  beds  are  characterized  by  species  of  Procamelus,  and  the 
related  Protolabis,  Protohippus,  Aphelops,  Mastodon  (M.  mirificus  of  Leidy), 
and  by  Deer  of  the  genera  Blastomeryx  and  Cosoryx,  together  with  Carni- 
vores of  the  genera  Canis  and  Machoerodus. 


912  HISTORICAL   GEOLOGY. 

The  Miocene  of  the  Atlantic  border  has  afforded  remains  of  many 
Cetaceans.  Among  them  are  various  Dolphins,  several  species  of  Whales 
of  the  genus  Squalodon,  related  <in  teeth  to  the  Zeuglodon,  the  largest 
about  30  feet  long.  Others  having  the  teeth  excessive  in  number,  or  multi- 
plicate,  and  provided  with  only  one  root ;  others  having  similar  teeth,  but 
only  in  the  upper  jaw,  as  in  the  genus  Physeter,  or  that  including  the  Sperm 
Whale ;  others  with  teeth  in  neither  jaw,  as  the  Baleen  or  Whale-bone 
Whales,  but  having  several  hundred  plates  of  the  so-called  whale-bone, 
growing  vertically  downward  from  above,  with  edges  of  fine  fibers,  to 
serve,  net-like,  for  gathering  food  of  small  Crustaceans  and  other  species 
from  the  ocean's  waters.  Fig.  1539  represents  a  restoration  of  a  species  of 

1539. 


CETACEAN.  —  Cetotherium  cephalus  (x  ^).    Kestoration  by  Cope. 

this  kind,  30  feet  long,  from  the  Maryland  Miocene,  the  Cetotherium  cephalus 
of  Cope  (1890).  The  head  of  the  Baleen  Whales  makes  about  a  third  of 
the  length  of  the  body. 

PLIOCENE.  —  The  Blanco  beds  of  the  Llano  Estacado,  western  Texas,  in 
the  Pliocene,  have  afforded  Cope  remains  of  a  Megalonyx,  Mastodon  mirificus, 
Equus  simplicidens  Cope,  a  Camel  of  the  genus  Pliauchenia,  and  some  other 
species. 

The  succession  of  forms  in  the  feet  and  teeth  under  the  Horse  type 
is  illustrated  by  Marsh  with  the  following  diagram.  The  plate  contains,  in 
a  series  of  seven  columns,  figures  of  the  fore  foot,  hind  foot,  lower  joint  of 
the  forearm  (made  up  of  the  radius  and  ulna),  the  same  of  the  leg  (tibia 
and  fibula)  ;  and  (5,  6,  7),  others  showing  the  length  of  the  teeth  and  the 
convolutions  within  them.  Columns  1  and  2  illustrate  the  fact  of  the 
diminishing  number  of  toes  with  the  progress  of  the  Tertiary,  until  at  last, 
in  the  modern  kind,  only  the  middle  or  third  toe  remains,  with,  either  side, 
rudiments  of  the  second  and  fourth  in  the  form  of  the  splint  bones,  while 
the  third  toe  has  become  increasingly  larger  and  longer.  In  the  regular  series, 
besides  the  genera  there  mentioned,  Epihippus  of  Marsh  is  an  intermediate 
genus  between  Orohippus  and  Mesohippus;  and  Desmatippus  of  Scott,  one 
between  Miohippus  and  Protohippus.  In  the  derivation  from  the  Tapir-like 
precursors,  the  type  of  the  Horse  became  distinct  when  the  middle  toe 
was  decidedly  stouter  than  that  either  side  of  it;  and  it  reached  its  maximum 
when  this  toe  was  the  only  one,  and  the  other  two  were  merely  "splint" 
bones. 


CENOZOIC  TIME  —  TERTIAHY. 


913 


1540. 
Fore  foot.   Hind  foot.  Forearm.  "Leg.  Tipper  molar.      Lower  molar. 


TV.   Recent. 
EQUUS. 

Ill    Pliocene. 


(2)  PLIOHIPPUS. 


(1)  PBOTOHIPPUS. 

II.  Miocene. 

(2)  MIOHIPPUS. 


(1)  MESOHIPPUS. 


Eocene. 

OROHIPPUS 
(  Hy  racotherium) . 


Illustrations  of  the  characters  of  successive  genera  under  the  Horse  type.    From  Marsh."" 

Another  important  fact  in  the  history  of  life  as  suggested  by  Lartet 
from  some  early  European  Mammals,  and  demonstrated  by  Marsh  from  the 
DANA'S  MANUAL  —  58 


914 


HISTORICAL   GEOLOGY. 


American,  is  the  increasing  size  of  the  brain  with  the  progress  of  the  Tertiary. 
In  most  of  the  earliest  Eocene  species  the  brain  was  extremely  small,  and 
especially  the  cerebral  or  anterior  part ;  that  of  the  Dinoceras  might  have 
been  drawn  entire  through  the  cavity  of  the  spinal  cord.  This  point  is 
illustrated  in  figures  1541-1543  (from  Marsh),  representing  the  skulls, 
reduced  to  a  common  length,  with  the  brain  cavity :  of  the  Eocene  Dinoceras 


1541 


1548 


Illustrations  of  the  sizes  of  brains  in  successive  genera  of  Ungulates.     Fig.  1541,  Dinoceras  (Eocene) ;  1542, 
Brontotherium  (Miocene) ;  1543,  Modern  Horse.    From  Marsh. 

(Tig.  1541),  the  Miocene  Brontotherium  (Fig.  1542),  and  the  modern  Horse 
(Fig.  1543).  The  Horse  has  a  brain  more  than  eight  times  the  bulk  of  that 
of  the  Dinoceras.  It  is  seen  in  these  figures  that  the  posterior  part  of  the 
brain,  as  Marsh  observes,  has  undergone  little  change  of  size,  the  enlargement 
having  been  eminently  in  the  cerebral  portion.  The  principle  has  necessarily 
its  exceptions,  since  size  is  not  the  element  of  most  importance  in  a  brain. 
Marsh  has  further  shown  that  the  principle  is  exemplified  in  fossil  Birds,  and 
also  in  the  Dinosaurian  group  of  Keptiles. 

In  addition  to  relics  of  Rodents  in  the  form  of  bones  and  teeth,  there  are, 
in  the  Niobrara  region,  what  have  been  supposed  to  be  burrows  of  some 
species  of  Eodent.  They  were  described  as  probably  fossil  Sponges  by 
E.  H.  Barbour  (Univ.  Studies,  Nebraska,  1892,  where  many  excellent  figures 
are  given,  some  showing  specimens  in  place).  They  stand  vertically,  in 
large  numbers,  in  the  Miocene  of  the  region,  some  of  them  8  or  9  feet  in 
height.  Each-  usually  ends  below  in  a  long  horizontal  or  oblique  chamber. 
Dcemonelix  is  a  Greek  form  (abbreviated)  of  the  popular  name  "Devil's 
corkscrew."  The  figure  includes  two  views  of  one  of  the  specimens,  the 
vertical  spiral  of  which  is  53  inches  high,  and  the  oblique  basal  portion 
76  inches. 


CENOZOIC   TIME  —  TERTIARY. 


915 


1544. 


r 

Two  views  of  a  specimen  of  Dsemonelix. 
E.  H.  Barbour. 


Since  Rodents  have  been  described  from  the  same  beds,  and  a  skeleton 
of  one  has  been  found  at  the  base  of  one  of  the  spirals,  there  has  seemed 
to  be  strong  reason  for  regarding  them  as  the  core  of  a  fossil  burrow ;  and 
this  has  appeared  to  be  confirmed  by  the  fact  that  the  skeleton  belonged  to 
a  Rodent  that  was  of  the  right 
size  to  have  made  the  spiral 
cavity.  But  according  to  the 
latest  investigations  of  E.  H. 
Barbour  (published  in  Novem- 
ber, 1894),  the  spiral  stems  or 
fillings  have  a  cellular  struct- 
ure, as  if  of  vegetable  origin. 
The  oblong  cells  average  one 
thirty-second  of  an  inch  in 
diameter,  but  vary  from  one 
sixty -fourth  to  one  eighth,  and 
even  to  one  fourth.  The  ex- 
terior is  made  of  these  tubules 
variously  intertwined.  The 
whole  of  a  spiral  and  its  long 
transverse  continuation  at  base 

have  the  cellular  structure.  "  Each  and  every  well-cut  section  shows  paren- 
chymatous  tissue,  no  matter  from  what  specimen,  or  from  what  portion  of 
an  individual  specimen,  the  section  is  made ;  there  has  not  been  an  excep- 
tion to  this."  The  final  conclusion  therefore  is  that  the  fossil  having  the 
spiral  form,  together  with  its  basal  portion,  was  probably  some  kind  of 
plant,  and  that  it  grew  around  the  inclosed  skeleton. 

Characteristic  Invertebrate  Species. 

EOCENE. 

1.  MIDWAY.  —  Enclimatoceras    Ulrichi  White,    Ostrea  Pulaskensis  Harris,    Ostrea 
prce-compressirostra  Har.,  Pecten  Alabamiensis  Aldrich,  Yoldia  eborea  Conrad,  Cucullcea 
macrodonta  Whitfield,  Cadulus  turgidus  Meyer,  Caricella  .LeanaDall,  Valuta  Showalteri 
Aldrich,  Volutilithes  rugatus  Conrad,  Volutilithes  limopsis  Con.,  Leucozonia  biplicata  Ald- 
rich,  Neptunea  constricta  Aldrich,  N.  Matthewsensis  Aldrich,  Pseudoliva   unicarinata 
Aldrich,  Murex  Alabamiensis  Aldrich,  Turritella  Alabamiensis  Whitfield. 

2.  LIGNITIC.  —  Maryland  and  Virginia :    Ostrea  compressirostra  Say,   Cucullcea  gi- 
gantea  Conrad,  Crassatella  alceformis  Conrad,  Dosiniopsis  lenticularis,   Cytherea  ovata 
Rogers,  Panopceaelongata  Conrad,  I'holadomya  Marylandica  Conrad,  Turritella  prcecincta 
Conrad.     Alabama :  Ostrea  comprpssirostra,  O.  thirsce  Gabb,  Cucullcea  gigantea  Con.,  var., 
Crassatella  tumidula  Whitfield,  Dosiniopsis  lenticularis,  Pholas  alatoidea  Aldrich,  Voluta 
Newcombiana  Whitfield,  Pseudoliva  tuberculifera  Conrad.     Upper  beds,  Alabama :  Fusus 
interstriatus  Heilprin,  Pleurotoma  moniliata  Heilprin,  Lcevibuccinum  lineatum  Heilp., 
Pseudoliva  scalina  Heilp.,  Corbula  Aldrichi  Meyer,  Cardium  ffatchetigbeense  Aldrich. 

3.  LOWER  CLAIBORNE. —  Ostrea  Johnsoni  Aldrich,  Anomia  ephippoides  Gabb,  Yoldia 
Claibornensis    Conrad,    Trigonarca  pulchra    Gabb,    Crassatella    antestriata    Gabb,    C. 


916  HISTORICAL   GEOLOGY. 

texalta  Harris,  C.  Texana  Heilp.,  C.  Trapaquara  Harris,  Astarte  protracta  Meyer,  Astarte 
Smithvillensis  Harris,  Lucina  Claibornensis  Conrad,  Pteropsis  lapidosa  Conrad,  Corbula 
oniscus  \&T.  fossata  Aid.,  Tellina  Mooreana  Gabb,  Solen  Lisbonensis  Aldrich,  Pholadomya 
Claibornensis  Aldrich,  Terebra  Houstonia  Harris,  Pleurotoma  beadata  Harris,  Pleurotoma 
Huppertzi  Harris,  Nassa  Dalli  Aldrich,  Nassa  scalata  Heilprin,  Phos  Texanus  Gabb, 
Distortrix  septemdentata  Gabb,  Odontopolys  compsorhytis  Gabb,  Volutilithes  Haleanus 
Whitfield,  Mazzalina  pyrula  Conrad  (typical),  Strepsidura  ficus  Gabb,  Clamlithes  Pen- 
rosei  Heilprin,  Neptunea  enterogramma  Gabb,  Turricula  polita  Gabb,  Borsonia  biconica 
Whitfield,  Mesalia  Claibornensis  Con.,  Turritella  nasuta  Gabb,  Eimella  Texana  Harris, 
Ancilla  ancillops  Heilp.,  Cassidaria  dubia,  Natica  recurva,  Belosepia  ungula  Gabb. 

4.  CLAIBORNE.  —  Crassatella  alta  Con.,  Panopcea porrectoides  Aid.,  Lutraria  papyria 
Con.,  Area  inornata  Meyer,  Cytherea  Mortoni  Con.,  Cytherea  cequorea  Con.,  Corbis  dis- 
tans  Con.,  Eingicula  biplicata  Lea,  Eimella  laqueata  Con.,  Caricella  doliata  Con.,  C.  Clai- 
bornensis Har.,    Clamlithes  pachyleurus  Con.,    Cerithium   Claibornense  Con.,   Mesalia 
obruta  Con.,  M.  vetusta  Con.,  Turritella  carinata  Lea. 

5.  JACKSON.  —  Ostrea  trigonalis  Con.,  Pecten  nuperus  Con.,  Leda  multiline ata  Con., 
Leda  mater  Meyer,   Crassatella  flexura  Con.,    Tellina  linifera  Con.,  Bullinella  Jack- 
sonensis  Meyer,  Haminea  grandis  Aldrich,  Pleurotoma  Heilprini  Aldrich,  P.  Americana 
Aldrich,  P.  perexilis  Aldrich,   Turricula  Millingtoni  Con.  (typical),  Conomitra  Hamma- 
keri  Har.,  Clamlithes  humerosus  Con.,  Fusus  pearlensis  Aldrich,    Conorbis  alatoideus 
Aldrich,   Cassidaria  Petersoni  Con.,   Turritella  alveata  Con.,  Turritella  arenicola  Con. 
(typical),  Turritella perdita  Con.,  Natica permunda  Con. 

6.  VICKSBURG.  —  Ostrea  Vicksburgensis  Con.,  Pecten  anatipes  Morton,  Pecten  Poulsoni 
Morton,  Byssoarca  protracta  Con.,  Area  Mississippiensis  Con.,  Pectunculus  arctatus  Con., 
Crassatella  Mississippiensis  Con.,  Cardium  diversum  Con.,  Cytherea  sobrina  Con.,  C.  imi- 
tabilis  Con.,  Dentalium  Mississippiense  Con.,  Pleurotoma  congesta  Con.,  P.  tenella  Con., 
P.  cristata  Con.,  P.  rotcedens  Con.,  P.  declivis  Con.,  P.  abundans  Con.,  Mitra  cellulifera 
Con.,  M.  conquisita  Con.,  Turbinella  Wilsoni  Con.,   Caricella  demissa  Con.,  Murex  sim- 
plex Aldrich,   Typhis  curvirostratus  Con.,   Oliva  Mississippiensis  Con.,  Fulgur  spiniger 
Con.,    Chenopus  liratus   Con.,    Oniscia  harpula  Con.,   Lyria  costata   Sow.,  Melongena 
crassicornuta  Con.,  Clamlithes  Mississippiensis  Con.,  Turritella  ccelatura  Con.,  T.  Missis- 
sippiensis Con.,  Solarium  triliratum  Con.,  Natica  Mississippiensis  Con. 

Ostrea  Georgiana,  Fig.  896,  was  originally  described  from  Shell  Bluff,  Ga.,  of  Lower 
Claiborne  horizon.  It  is  doubted  whether  it  is  rightly  made  a  Vicksburg  species. 

A  specimen  containing  Eocene  fossils  has  been  reported  by  Upham  and  Crosby  from 
the  drift  of  Cape  Cod. 

In  California,  in  the  Tejon  group,  occur,  according  to  Gabb,  Ammonites  (A.  jugalis 
Gabb),  Fusus,  Surcula,  Typhis,  Tritonium,  Nassa,  Pseudoliva,  Olivella,  Fasciolaria, 
Mitra,  Ficus,  Natica,  Lunatia,  Neverita,  Naticina,  Scalaria,  Terebra,  Niso,  Cerithiopsis, 
Architectonica,  Conus,  Eimella,  Cyprcea,  Loxotrema,  Turritella,  Galerus,  Nerita,  Mar- 
garitella,  Gadus,  Bulla,  Solen,  Corbula,  Necera,  Tellina,  Donax,  Venus,  Meretrix,  Dosinia, 
Tapes,  Cardium,  Cardita,  Lucina,  Crassatella  (C.  alta  Con.),  Mytilus,  Modiola,  Avicula, 
Area,  Axincea,  Pecten,  Ostrea,  with  the  coral  Trochosmilia  striata  Gabb. 


MIOCENE. 

1.  CHATTAHOOCHEE.  —  Orthctulox  pugnax  Heilprin,  Pyrazisinus  campanulatus  Heilp., 
P.  acutus  Heilp.,  Cerithium  Hillsboroense  Heilp.,  Potamides  transsectusDa.il,  Vasum  sub- 
capitellum  Heilp.,  Coralliophila  magna  Dall,  Ampullina  solidula  Dall,  Turritella  Tampce 
Heilp.  The  fauna  of  the  Chattahoochee  deposits  where  typically  exposed  has  not  been 
carefully  studied  ;  the  above-mentioned  species  are  mainly  from  near  Tampa. 


CENOZOIC    TIME  —  TERTIARY.  917 

2.  CHIPOLA.  —  Orthaiitax  Gabbi  Dall,  Strombus  Aldrichi  Dall,  Turritella  subgrun- 
difera  Dall,  T.  Chipolana  Dall,  Pollinices   Burnsii  Dall,  Ampullina  Fischeri  Dall,  Clava 
Chipolana  Dall,  Bittium  Chipolanum  Dall,  Modulus  compactus  Dall,   Turritella  indenta 
var  wi'osta  Dall,  Tuba  acutissima  Dall. 

3.  YORKTOWN.  —  Ostrea  percrassa  Con.,  0.  disparilis  Con.,  Pecten  Jeffersonius  Say, 
P.  Madisonius  Say,  P.  Clintonius  Say,  Mytiloconcha  incurva  Con.,  ^4rca  idonea  Con., 
w4.  subrostrata  Con.,  A  incilis  Say,  Striarca  centenaria  Say,  Pectunculus  subovatus  Say, 
P.  quinquerugatus  Con.,  Astarte  undulata  Say,  Crassatella  undulata  Say,  O.  melina  Con., 
<7.  Marylandica  Con.,  Lucina  anodonta  Say,  .L.  cribraria  Say,  Diplodonta  acclinis  Con. , 
Carditamera  arata  Con.,  Cardium  laqueatum  Con.,  Terms  cortinarea  Rogers,  Cytherea 
Marylandica  Con.,  (7.  staminea  Con.,  Isocardia  fraterna  Say,  Dosinia  acetabula  Con., 
Mactra  delumbis  Con.,  Petricola  centenaria  Con.,  Panopcea  re/f  eza .  Say,  P.  ^Imm'ccwa 
Con.,  Pholadomya  abrupta  Con.,  Corbula  idonea  Con.,  Tellina  biplicata  Con.,  Terebra  sim- 
plex Con.,  Ecphora  quadricostata  Say,  Fasciolaria  rhomboidea  Rogers,  Typhis  acuticosta 
Con.,  Urosalpinx  trossulus  Con.,  Fusus parilis  Con.,  F.  exilis  Con.,  P.  strumosus  Con. 

The  Miocene  species  of  the  Ashley  Marl  bed,  South  Carolina,  determined  by  Dall  (1894,) 
include  Astarte  vicina  Say,  Ecphora  quadricostata,  an  Amusium  not  distinguishable  from 
-4.  Mortoni,  Lucina  contracta,  Dentalium  attenuatum,  Pecten  decennarius,  with  others  of 
Corbula,  Leda,  Yoldia,  Tellina,  Marginella,  Solen,  Modiola.  The  species  show  closer 
relations  to  the  Yorktown  epoch  than  to  the  Chipola.  Dall  adds  that  the  change  in  the 
rock  to  the  phosphate  condition  probably  took  place  in  Pliocene  time  like  that  of  the 
similar  phosphatic  pebbles  of  Peace  River,  Fla. 

The  Miocene  of  Gay  Head,  Martha's  Vineyard,  afforded  Dall :  Carcharodon  angus- 
tidens,  Hemipristis  serra,  Oxyrhina  hastalis  ;  the  Crustacean  Archceoplax  signifera 
Stimson  ;  the  Mollusks,  Yoldia  limatula,  Y.  sapotilla,  Cardium  Virginianum,  Nucula 
Shaleri  Dall,  Gemma  purpurea  var.  Totteni,  My  a  arenaria,  My  a  truncata,  Glycimeris 
reflexa,  Chrysodomus  Stonei  Pilsbury.  The  overlying  Pliocene  contained,  according  to 
J.  B.  Woolworth,  Corbicula  denSata,  and  Venericardia  borealis  of  Pliocene  type. 

PLIOCENE. 

FLORIDIAN.  — Area  scalarina  Heilp.,  Arcoptera  aviculceformis  Heilp.,  Area  crassicosta 
Heilp.,  Chama  crassa  Heilp.,  .Cardium  Dalli  Heilp.,  Venus  rugatina  Heilp.,  Cythara  ter- 
minula  Dall,  Strombus  Leideyi  Heilp.,  Siphocyprcea  problematica  Heilp.,  Vasum  horridum 
Heilp.,  Fasciolaria  scalarina  Heilp.,  Liochlamys  bulbosa  Heilp.,  Turbinella  regina  Heiip. 

The  above  lists  of  Atlantic  border  and  Gulf  border  species  are  from  G.  D.  Harris. 
The  species  are  "characteristic"  in  being  found  "  either  exclusively,  typically,  or  most 
abundantly,  in  the  group  where  mentioned." 

Characteristic  Genera  of  Vertebrates. 

In  this  list  of  genera  the  names  of  those  which  occur  in  corresponding  beds 
abroad  are  put  in  small  capitals ;  those  which  are  represented  by  existing 
species  are  followed  by  an  interjection  mark. 

EOCENE. 

PUERCO  GROUP.  —  Monotremes  or  Marsupials  (Multituberculates):  Ptilodus,  Neopla- 
giaulax,  Chirox,  Polymastodon.  Tillodonts :  Psittacotherium.  Ungulates  :  Haploconus, 
Periptychus,  Protogonia,  Protogonodon ;  Pantolambda.  Creodonts :  Oxyclcenus,  Penta- 
codon,  Triisodon,  Microclcenodon,  Dissacus,  Deltatherium,  Didymictis.  Quadrumana 
(Lemuroids) :  Mixodectes,  Indrodon. 

WASATCH  GROUP.  —  Rodents:  Paramys.  Tillodonts:  Dryptodon,  ESTHONVX,  CALA- 
MODON.  Ungulates:  Phenacodus,  Trispondylus,  Meniscotherium,  Hyracops ;  Coryphodon, 


918  HISTORICAL   GEOLOGY. 

Manteodon,  Ectacodon,  Metalophodon ;  HTRACOTHERIUM,  Eohippus,  Systemodon,  HEP- 
TODON,  Lambdotherium ;  Artiodactyl  Ungulates,  Pantolestes,  Homacodon,  Eohyus, 
PAchcenodon.  Insectivores :  Diacodon.  Creodonts :  Anacodon,  f  Dissacus,  Pachycena, 
SINOPA,  Didelphodus,  PAL^ONICTIS,  Oxycena,  Miacis,  Didymictis.  Quadrumana  :  Anap- 
tomorphus,  HYOPSODUS,  Pelycodus,  Cynodontomys,  Microsyops. 

WIND  RIVER,  GREEN  RIVER  GROUPS.  —  Rodents:  Paramys.  Tillodonts  :  Esthonyx, 
Calamodon.  Ungulates :  Phenacodus,  Trispondylus ;  Coryphodon,  Bathyopsis ;  Hyraco- 
therium,  Pachynolophus,  Lambdotherium,  Palceosyops ;  Artiodactyl  Ungulates,  Panto- 
lestes. Insectivores  :  Ictops.  Chiropters  :  Vesperugo.  Creodonts :  Sinopa,  Patriofelis,, 
Miacis,  Didymictis.  Quadrumana  :  Microsyops,  Pelycodus. 

BRIDGER  GROUP.  —  Rodents:  Paramys,  My  sops.  Tillodonts:  Anchippodus,  Tillothe- 
rium.  Ungulates  :.  Uintather turn,  Dinoceras,  Tinoceras ;  Orohippus,  Lambdotherium, 
Palceosyops,  Limnosyops,  Telmatherium,  Hyrachyus,  Helohyus,  Colonoceras,  Triplopus, 
Helaletes,  ISECTOLOPHUS,  Amynodon ;  Artiodactyl  Ungulates,  Achcenodon,  HOMACODON, 
Nanomeryx,  Helohyus,  Ithygrammodon.  Insectivores  :  Ictops,  Palceacodon,  ?  Passalaco- 
don.  Rodent :  f  Apatemys.  Chiropters  :  Nyctilestes,  f  Vesperugo.  Creodonts  :  Miacis, 
Didymictis,  Mesonyx,  SINOPA,  PROVIVERRA,  ?  Viverravus,  Patriofelis.  Quadrumana : 
HYOPSODUS,  Notharctus,  Microsyops,  Tomitherium,  ?  Lemur avus. 

UINTA  GROUP.  —  Rodents  :  Paramys.  Ungulates  :  Epihippus,  Triplopus,  Amynodon, 
Isectolophus,  Diplacodon  ;  Artiodactyl  Ungulates,  Protoreodon,  Hyomeryx,  Leptotragulus> 
Oromeryx.  Creodonts  :  Mesonyx,  ?  Miacis.  Quadrumana  :  Hyopsodus. 

MIOCENE. 
1.   LOWER  MIOCENE. 

A.  WHITE  RIVER  GROUP.  —  (In  part,  Oligocene  of  W.  B.  Scott.) 

(1)  Titanotherium  beds.  —  Ungulates:    Titanotherium,  Brontotherium,   Brontops ,* 
Teleodus,  C^NOPUS,  Mesohippus,  Colodon  ;  SCHIZOTHERIUM  (Canada)  ;  Artiodactyl  Ungu- 
lates, f  Oreodon,  ELOTHERIUM,  ANCODUS  (HYOPOTAMUS),  ANTHRACOTHERIUM,  Poebrothe- 
rium,  9 Leptomeryx,  ? Hypertragulus.    Creodonts  :  Hemipsalodon  (near  Pterodon,  Canada). 

(2)  Oreodon   beds.  —  Marsupials:  DIDELPHYS  !     Rodents:    Ischyromys,   Gymnopty- 
chus,  Heliscomys,   STENEOFIBER,   SCIURUS,   EUMYS,  Palceolagus.     Ungulates:    MESOHIP- 
PUS, C^ENOPUS,  Hyracodon,  Metamynodon,  Colodon,  PROTAPIRUS  ;  Artiodactyl  Ungulates, 
Oreodon,  Agriochcerus,  ANCODUS  ;  ELOTHERIUM,  ANTHRACOTHERIUM,  PERCH<ERUS,  Lepto- 
choerus,  Poebrotherium  ;  Leptomeryx,  Hypertragulus,  Hypisodus,  Stibarus.  —  Insectivores  : 
Ictops,   Leptictis,   Mesodectes,   Geolabis.       Chiropters :    ?  Domnina.      Creodonts :   HY^- 
N'ODON.       Carnivores :     Daphcenus,     CYNODON,     DINICTIS,     Hoplophoneus,    Bunadurus. 
Quadrumana :  ?  Laopithecus. 

(3)  Protoceras  beds.  —  (Rodents  not  studied.)     Ungulates :  C^ENOPUS,  DICERATHE- 
RIUM,  Hyracodon;  fMiohippus;  PROTAPIRUS;  Artiodactyl  Ungulates,   Oreodon,   ? Epo- 
reodon,  Agriochcerus,  Coloreodon;  Leptauchenia,  ANCODUS;  ANTHRACOTHERIUM,  Perchce- 
rus  ;  Leptomeryx  ;  Protoceras.     Creodonts  :  Hycenodon.    Carnivores  :  CYNODON,  DINICTIS, 
Hoplophoneus,  ? Pogonodon. 

B.  JOHN  DAY  GROUP.  —  Rodents :  Allomys,  SCIURUS,  STENEOFIBER,  Sitomys,  Paci- 
culus,    Pleurolichus,   Eutoptychus,    Palceolagus,    Lepus !     Ungulates :   MACROTHERIUM  ; 
CJENOPUS,  DICERATHERIUM  ;  Miohippus ;  ?  PROTAPIRUS  ;  Artiodactyl  Ungulates,  Eporeo- 
don,  Mesoreodon*,  Merycochcer us,  Agriochcerus,  Coloreodon  (Agriomeryx") ,  Hypertragu- 
lus; Poebrotherium,  Gomphotherium ;  Elotherium,  Chcenohyus,  Bothriolabis,  Thinohyus. 
Carnivores  :  Daphcenus,  CYNODON,  Temnocyon,  Cynodesmus  *,  Enhydrocyon,  Hycenocyon, 
Oligobunis,  Archcelurus,  Dinictis,  Hoplophoneus,  Nimravus,  Pogonodon,  Parictis. 

(The  genera  in  small  caps  are  found  in  the  Lower  Miocene  of  Europe.  The  genera,  the 
names  of  which  have  an  asterisk  added,  are  known  only  from  the  John  Day  of  Montana.} 


CENOZOIC   TIME — TERTIARY.  919 

2.  UPPER  MIOCENE. 

LOUP  FORK  GROUP.  —  (1)  Deep  River  beds.  (Ticholeptus  beds. )—  Ungulates  t 
Miohippus,  Desmatippus*,  Anchitherium,  Protohippus,  Aphelops,  MASTODON. 

(2)  Nebraska  beds  or  Loup  Fork  proper.  —  Rodents :  STENEOFIBER,  Sitomys  (Hes- 
peromys),  Hystricops,  Palceolagus,  Panolax.  Edentates:  Caryoderma.  Ungulates: 
Chalicotherium,  Pliohippus,  Protohippus,  HIPPARION,  ?  Tapir  avus,  Aphelops ,  Teleoceras  ; 
Artiodactyl  Ungulates,  Merychyus,  Merycochwrus,  Protolabis,  Procamelus,  Platygonus, 
Pliauchenia,  BLASTOMERYX,  Cosoryx.  Proboscideans  :  MASTODON.  Carnivores  :  ?  CANIS  L 
^Elurodon,  PSEUD^ELURUS,  MACHYERODUS,  STENOGALE,  Brachypsalis. 

PLIOCENE. 

1.  Palo  Duro  beds. — Rodents:    ?  Arctomys,    ?  Gfeomys.      Ungulates:   Protohippus, 
Equus!,  Hippidium,  Aphelops,'  Artiodactyl  Ungulates,  large  Camel,  probably  Pliauche- 
nia.    Proboscidean:  Mastodon. 

2.  Blanco  beds. — Edentates:  Megalonyx.     Ungulates:  EQUUS!;  Artiodactyl  Ungu- 
lates, Platygonus,  Pliauchenia.      Proboscidean:  MASTODON.      Carnivores:    Canimartes, 
Borophagus,  ?  FELIS  ! 

The  preceding  list  of  genera  has  been  prepared  for  this  place,  for  the  most  part,  by 
W.  B.  Scott. 

The  more  important  publications  on  North  American  Tertiary  Mammals  and  their 
historical  relations,  are  those  of  Leidy  on  the  Mammalian  Fauna  of  Dakota  and  Nebraska 
(1869),  and  other  memoirs  ;  Marsh,  on  the  Introduction  and  Succession  of  Vertebrate  life 
in  America  (1877),  and  his  many  earlier  and  later  papers  ;  Cope,  on  horizons  of  Extinct 
Vertebrates  (1878),  on  the  Origin  of  the  Fittest  (1887),  and  his  other  various  publications  ; 
H.  F.  Osborn,  on  The  Rise  of  the  Mammalia  of  North  America  (1893),  and  other  memoirs  ; 
and  papers  by  W.  B.  Scott. 


FOREIGN. 

Notwithstanding  the  catastrophe  that  produced  over  the  continental  seas 
the  wide  exterminations  of  species  which  closed  Mesozoic  time,  Europe  in 
the  earlier  part  of  the  Tertiary  era  was  much  like  Europe  of  the  Cretaceous 
period.  In  the  interval  there  had  been  emergencies  and  a  widening  of  the 
areas  of  dry  land ;  yet  nearly  half  the  continent  south  of  the  parallel  of  55° 
remained  under  salt  water,  or  was  barely  emerged.  There  were  frequent 
oscillations  during  the  progress  of  the  Eocene ;  but  in  its  later  part  the  sea 
had  great  extent  over  southern  Europe,  covering,  in  part,  the  sites  of  the 
chief  mountain  ranges  and  spreading  largely  over  Asia.  Great  Britain  was 
still  continuous  with  Europe,  and  the  London-Paris  basin  was  one  of  the 
large  local  seas ;  but  that  basin  had  narrowed  limits  in  southeastern  England 
and  also  in  France.  After  the  Eocene  the  conditions  were  changed  by  the 
making  and  partial  elevation  of  the  Pyrenees  and  large  emergencies  else- 
where, but  part  of  the  region  of  the  Alps  and  Juras  was  still  producing  rocks 
for  the  finishing  of  the  mountains. 

The  contrast  with  Tertiary  North  America  was  great.  There  was  no 
localized  sea-border  belt  of  accumulating  deposits ;  and  what  it  had  of  inte- 
rior lakes  were  estuarine  or  lacustrine  in  alternation  with  marine  conditions. 


920  HISTORICAL   GEOLOGY. 

Consequently,  Mammalian  life  is  much  less  perfectly  represented  in  the 
European  Tertiary  than  in  the  North  American. 

ROCKS  — KINDS  AND  DISTRIBUTION. 

In  England,  beds  of  the  Eocene  occur  in  the  London  and  Hampshire 
basins,  resting  on  the  Chalk.  The  Lower  Eocene  consists  of  beds  of  sand, 
with  marine  fossils  called  the  Thanet  sands,  with  some  clay-beds  above,  and 
the  London  Clay,  an  estuarine  deposit,  500  feet  in  maximum  thickness,  which 
has  afforded  many  species  of  fossil  leaves  and  Eocene  Mammals,  besides 
marine  shells.  The  Middle  and  Upper  Eocene  consist  of  marine  fossil- 
iferous  sands  called  the  Bagshot  beds,  with  some  leaf-bearing  clay-beds. 
Among  the  fossils  occur  some  Nummulites,  species  that  were  abundant 
farther  south  over  Europe. 

In  northern  France  and  Belgium  there  is  a  general  resemblance  in  the 
Eocene  strata  to  those  of  the  British  part  of  the  London-Paris  basin.  The 
Lower  are  clay-beds,  marlytes,  and  sand-beds,  partly  marine,  but  containing 
in  some  parts  Plants  and  Mammals.  The  Middle  Eocene  in  France  consists 
largely  of  a  coarse  limestone,  the  Calcaire  grassier,  partly  glauconitic  and 
Nummulitic ;  and  the  Upper  is  a  series  of  sand-beds,  sandstones,  and  marls, 
with  some  limestones,  having  at  top  a  bed  containing  gypsum  100  to  160  feet 
thick,  containing  in  some  layers  nodules  of  opal-silica  (menilite). 

In  southern  Europe  the  Eocene  beds  are  largely  Nummulitic  limestones 
of  great  thickness;  and  they  range  widely  from  southern  France,  the 
Pyrenees,  and  Spain,  over  much  of  the  region,  eastward  to  Asia  Minor  and 
beyond,  indicating  a  pure  sea  of  great  extent.  The  Nummulitic  beds  are 
3000  feet  thick  in  southern  France.  In  the  Alps  they  constitute  the  summits 
of  the  Dent  du  Midi,  10,531  feet,  of  Diablerets,  10,670  feet  in  elevation, 
and  of  other  heights.  They  occur  in  the  Apennines  and  the  Carpathians. 
They  extend  into  Egypt  (where  the  Pyramids  were  in  part  made  of  Num- 
mulitic limestone) ;  also  through  Algeria  and  Morocco,  parts  of  Asia  Minor, 
Persia,  Caucasus,  India,  the  mountains  of  Afghanistan,  the  southern  slopes 
of  the  Himalayas,  and  to  a  height  of  20,000  feet  in  middle  Tibet.  They 
occur  also  in  Japan,  on  Luzon  in  the  Philippine  Islands,  and  in  Java. 

Oligocene  beds  of  alternate  salt  and  fresh  water  origin  are  found  in  the 
Isle  of  Wight  and  the  Hampshire  basin.  In  the  Paris  basin,  in  France, 
they  are  largely  of  freshwater  origin.  They  include  the  Gres  de  Fonfcaine- 
bleau  in  the  Paris  basin,  and  below,  marlytes,  with  gypsum,  affording  remains 
of  Mammals  at  the  quarries  of  Montmartre.  They  have  wide  distribution  in 
north  Germany,  and  hold  in  the  lower  part  beds  of  brown  coal  with  remains 
of  plants.  In  Switzerland  they  constitute  the  lower  lacustrine  part  of  the 
sandstone  formation  called  Molasse,  having  a  thickness  of  7000  feet.  The 
beds  called  Flysch  are  at  the  base  of  the  Oligocene. 

Miocene  Tertiary  beds  are  not  recognized  in  England  or  in  the  Paris 
basin,  and  are  mostly  confined  to  scattered  areas  which  are  only  in  part 


CENOZOIC   TIME  —  TERTIARY.  921 

marine.  The  upper  part  of  the  Molasse,  mostly  marine,  is  Miocene.  The 
beds  of  CEningen,  on  Lake  Constance,  affording  Insects  in  fine  preservation, 
along  with  leaves  and  some  Mammals,  Birds,  and  other  species,  are  of  the 
Upper  Miocene.  Among  the  noted  (Eniugen  fossils  is  the  Homo  diluvii  testis 
of  Scheuchzer  (1700),  shown  by  Cuvier  to  be  an  aquatic  Salamander. 

The  Miocene  has  a  thickness  of  10,000  feet  in  northern  Italy  and  the 
Ligurian  Alps,  and  extends  southward.  It  occurs  also  in  Sicily  and  Malta. 

The  Marine  Pliocene  of  Europe  is  mostly  found  along  the  sea  border. 
This  is  its  position  in  eastern  England,  where  it  is  called  the  Crag,  in  Bel- 
gium, and  on  the  French  Mediterranean  coasts ;  but  in  Italy  the  beds  spread 
more  widely  along  both  sides  of  the  Apennines,  and  in  Sicily  they  have  an 
elevation  in  some  places  of  3000  feet. 


LIFE. 

PLANTS.  —  The  higher  plants  were  mainly  Angiosperms,  Conifers,  and 
Palms. 

The  Isle  of  Sheppey  is  famous  for  its  fossil  fruits ;  and  among  them  are 
those  of  several  species  of  Palm,  related  to  the  Nipce  of  the  Moluccus  and 
Philippine  Islands,  England  in  the  Eocene  having  been  a  land  of  Palms. 
In  the  Middle  Eocene,  in  England,  there  were  species  of  Fig,  Cinnamon, 
various  Proleacece,  etc.,  indicating  a  climate  and  flora  much  like  that  of  India 
and  Australia.  In  the  Tyrol,  Eocene  beds  contain  Palms ;  nearly  a  third 
of  the  plants  were  Australian  in  character,  and  a  fifth  were  allied  to  plants 
of  tropical  America.  The  Oligocene  contains,  in  its  lignitic  beds,  species  of 
Taxites,  Cupressinoxylon,  Sequoia,  and  affords  elsewhere  leaves  of  Laurus, 
Cinnamomum,  Magnolia,  Sassafras,  Quercus,  with  Palms  of  the  genera  Sabal, 
Flabellaria,  Phcenicites.  In  the  Miocene,  Palms  were  absent  from  England, 
and  the  forests  of  Europe  had  lost  their  tropical  character.  It  is  remarkable 
that  a  much  larger  proportion  of  species  than  now  were  of  North  American 
type,  showing  that,  while  the  Eocene  vegetation  of  Europe  was  largely  Aus- 
tralian, the  second  or  Miocene  phase  (including  in  part  at  least  the  Upper 
Eocene  of  Lyell)  was  more  like  that  of  North  America  than  now.  In  the 
Pliocene,  the  Flora  embraced  the  modern  genera  of  Rose,  Plum,  Almond, 
Myrtle,  Acacia,  Whortleberry.  There  were  also  species  of  the  genera  (now 
unknown  in  Europe)  of  Taxodium,  Comptonia,  Liquidambar,  Nyssa,  Robinia, 
Gleditschia,  Cassia,  Rhus,  Juglans,  Ceanothus,  Celastrus,  Liriodendron,  indicat- 
ing that  there  was  still  a  strong  American  character.  Moreover,  certain 
genera,  as  that  of  the  Oak  (Quercus),  which  have  numerous  species  in 
America,  had  many  in  Pliocene  Europe,  but  have  few  now. 

In  Greenland,  according  to  Heer,  Eocene  beds,  named  by  him  the  Unartok 
series,  occur  on  the  shores  of  Disco  Island,  containing  species  of  Magnolia, 
Laurus,  Juglans,  Quercus,  Sequoia  (S.  Langsdorffi) ;  and  Miocene  beds  of 
the  Atanekerdluk  series,  that  have  afforded  187  species  of  plants,  including 
the  same  Sequoia,  Glyptostrobus  Europwus,  Taxodium  distichum,  Taxites 


922  HISTORICAL   GEOLOGY. 

Olriki,  Onoclea  sensibilis  and  species  of  Fagus,  Platanus,  Salix.  Dawson 
refers  the  former  to  the  Laramie,  and  the  latter  to  the  Eocene  (1888).  Spitz- 
bergen,  in  lat.  78°  56',  has  yielded  many  species,  including  two  species  of 
Taxodium,  and  species  of  Hazel,  Poplar,  Alder,  Beech,  Plane  Tree  and  Lime. 
But  it  is  now  questioned  whether  part  of  the  Miocene  of  Greenland  is 
not  Eocene. 

Out  of  180  species  from  the  Eocene  beds  of  Haring,  55,  according  to  Ettingshausen, 
are  Australian  in  type,  28  East  Indian,  23  tropical  American,  14  South  African,  8  Pacific, 
7  North  American  and  Mexican,  6  West  Indian,  5  South  European.  The  resemblance  to 
Australia  consists  not  merely  in  the  number  of  related  species,  but  in  their  character,  — 
the  small,  oblong,  leathery-leaved  Proteacece  and  Myrtacece,  the  delicately- branching 
Casuarince,  the  Cypress-like  species  of  Frenela  and  Callitris,  etc.  Only  11  species  have 
their  representatives  in  warm  temperate  climates. 

In  the  Miocene  of  Vienna,  nearly  a  third  are  North  American  in  type  ;  but  with  these 
there  are  some  South  American,  East  Indian,  Australian,  central  Asiatic,  and  not  a  sixth 
European.  The  species  particularly  related  to  those  of  North  America  (its  warmer  por- 
tion) belong  to  the  genera  Fagus,  Quercus,  Liquidambar,  Laurus,  Bumelia,  Diospyros, 
and  Andromedites. 

ANIMALS. — No  fossil  Invertebrate  or  Vertebrate  of  the  Cretaceous  of 
Great  Britain  is  known  from  the  Tertiary ;  and  this  is  true  also  for  Europe. 
Invertebrates.  —  The  shells  of  Rhizopods,  Foraminifers,  were  as  important 
in  rock-making  during  the  Eocene  Tertiary  as  during  the  Cre- 
taceous.    The  species  of  greatest  interest  are  the  coin-shaped 
Nummulites  which  contributed  largely  to  the  constitution  of 
Eocene  strata,  as  already  stated.     A  common  species  is  here 
represented,  with  the  exterior  of  half  of  it  removed,  so  as 
to  show  the  spiral  ranges  of  cells  that  were  formed  by  the 
-  successive  budding  of  Rhizopods.     There  are  but  few  Brachio- 
pods  known,  and  these  are  mostly  of  the  groups  of  Lingulids, 
Discinids,  Terebratulids  and  Rhynchonellids. 

The  Mollusks  were  nearly  all  of  modern  genera.  Some  of  the  common 
Eocene  Gastropods  are  species  of  Oliva,  Fusus,  Voluta,  Fasciolaria,  Conus, 
Mitra,  Cerithium,  Turritella,  Rostellaria,  Pleurotoma,  Cyprcea,  Natica,  Scalaria. 
England  had  six  species  of  Eocene  Nautilus. 

Insects,  and  also  Arachnids  and  Myriapods,  have  been  obtained  in  great 
numbers  from  the  amber  in  the  Lignitic  portions  of  the  Lower  Oligocene 
of  northern  Germany,  near  Konigsberg.  Over  2000  species  have  been 
collected  from  it.  They  were  caught  in  the  resin  while  it  was  in  its  original 
liquid  state,  and  the  most  delicate  parts  are  preserved  in  perfection.  The 
lignite  was  made  chiefly  from  Conifers,  and  the  common  species  is  a  Pinus, 
P.  succinifer.  They  show  that  forests  of  Conifers  were  a  common  featuro 
of  northern  Europe.  Insects  occur  also  abundantly  in  the  Middle  Tertiary 
of  (Eningen,  Radoboj,  Parschlug,  Auvergne,  and  in  the  Rhenish  Brown  coal. 

Vertebrates.  — Among  Fishes,  Teleosts,  or  common  Fishes,  which  began  in 
the  Cretaceous,  were  profusely  represented.  Ganoids  were  relatively  few;, 


CENOZOIC    TIME  —  TERTIARY.  923 

and  among  them  in  the  Eocene  occurred  species  of  Acipenser  or  Sturgeon. 
Teeth  of  Sharks  are  also  common,  and  are  like  those  of  America  in  genera 
and  partly  in  species. 

Among  Reptiles,  there  were  many  true  Crocodiles,  — 18  or  20  species 
having  been  described.  Over  60  species  of  Tertiary  Turtles  are  known ;  and 
the  shell  of  one  Indian  species  from  the  Pliocene  of  the  Siwalik  Hills, 
Testudo  (Colossochelys)  Atlas,  had  a  length  of  six  feet. 

A  species  of  Snake,  20  feet  long,  Palceophis  typhceus  Owen,  was  discovered 
in  the  Bracklesham  beds  of  the  Middle  Eocene,  and  another  species,  30  feet 
long,  in  the  Lower  Eocene  of  Sheppey.  Several  species  related  to  the  com- 
mon Black  Snake  (Colubridce)  occur  in  the  Miocene. 

Remains  of  a  large  number  of  Tertiary  Birds  have  been  found  and 
described.  According  to  A.  Milne  Edwards,  the  Miocene  beds  of  the  Depart- 
ment of  Allier,  in  central  France  (between  46°  and  47°  in  latitude),  has 
alone  afforded  70  species ;  and  many  of  these  Miocene  birds  are  of  tropical 
character.  He  thus  speaks  of  them:  Parrots  and  Trogons  inhabited  the 
woods.  Swallows  built,  in  the  fissures  of  the  rock,  nests  in  all  probability 
like  those  now  found  in  certain  parts  of  Asia  and  the  Indian  Archipelago. 
A  Secretary  Bird,  nearly  allied  to  that  of  the  Cape  of  Good  Hope,  sought  in 
the  plains  the  serpents  and  reptiles  which  at  that  time,  as  now,  must  have 
furnished  its  nourishment.  Large  Adjutants,  Cranes,  and  Flamingoes,  the 
Palcelodi  (birds  of  curious  forms,  partaking  of  the  characters  both  of  the 
Flamingoes  and  of  ordinary  Grallae)  with  Ibises  frequented  the  banks  of 
the  watercourses,  where  the  larvae  of  Insects  and  Mollusks  abounded ;  Peli- 
cans floated  in  the  midst  of  the  lakes  ;  and,  lastly,  Sand-grouse  and  numerous 
gallinaceous  birds  assisted  in  giving  to  this  ornithological  population  a  strange 
physiognomy,  which  recalls  to  mind  the  descriptions  that  Livingstone  has 
given  us  of  certain  lakes  of  southern  Africa. 

The  London  Clay  (Eocene)  afforded  Owen  a  bird,  named  by  him  Odon- 
topteryx,  having  tooth-like  dentations  of  the  bony  edge  of  the  bill. 

The  Mammals  of  Europe  were  much  like  those  of  America  in  the  charac- 
teristics of  the  earliest  known  species  and  in  the  lines  of  succession.  The 
beds  of  the  Lower  Eocene  of  Europe,  the  Cernaysian,  near  Reims,  and  else- 
where, in  France,  have  afforded  kinds  of  Ungulates,  Creodonts,  and  Quad- 
rumana,  related  to  those  of  the  Puerco  group.  Remains  of  species  of 
Zeuglodon  have  been  reported  from  England,  France,  Germany,  Russia,, 
and  even  from  New  Zealand.  The  London  Clay  of  the  London  basin,  repre- 
senting the  Middle  Eocene,  has,  like  the  Wasatch,  its  species  of  Coryphodon 
and  Hyracotherium,  genera  first  established  by  Owen  from  British  species, 
and  also  new  Creodonts ;  and  the  Upper  Eocene,  including  the  Calcaire 
grassier  of  Paris,  is  like  the  Bridger  group  in  its  Ungulates,  Creodonts, 
and  Quadrumana,  the  genera  Lophiodon,  Hyrachyus,  being  characteristic. 
Further,  the  Uinta  beds,  or  those  of  the  closing  Eocene,  have  equivalents  in. 
the  Gypsum  beds  of  Montmartre  of  the  Paris  basin,  the  beds  that  afforded 
Cuvier  the  earliest  known  of  Tertiary  Mammals.  These  Parisian  strata,  the 


924 


HISTORICAL   GEOLOGY. 


•Calcaire  grossier,  and  the  beds  of  the  Montmartre  Quarries  are  referred  to 
the  upper  section  of  the  Eocene  in  French  geology ;  the  latter  is  the  Lower 
Oligocene  of  other  parts  of  Europe. 

The  same  general  facts  are  true  with  regard  to  the  Mammals  of  the 
Lower  Miocene  corresponding  to  the  White  River  beds  of  America,  desig- 
nated Upper  Oligocene  in  Germany,  and  to  those  of  the  later  Miocene  and 
Pliocene. 

Among  the  species  of  the  Upper  Eocene,  brought  to  new  existence  by 
Cuvier  from  the  beds  in  the  vicinity  of  Paris,  one  of  the  most  characteristic 
is  the  Paleothere  (named  from  TraAcuo's,  ancient,  and  Ojp,  wild  beast),  related 

to  the  Tapir  in  its  elongated  nose  and 

1546.  other    respects.     The   restoration    by 

Cuvier  has  a  close  resemblance  to  the 
figure  of  the  Tapir  on  page  905. 
The  largest  species  of  the  genus, 
Palceotherium  magnum  Cuv.,  was  of 
the  size  of  a  horse,  and  a  smaller, 
P.  curtum  Cuv.,  not  larger  than  a 
sheep.  The  restoration  by  Cuvier 
has  the  stout  form  of  the  Tapir; 
but  a  skeleton,  discovered  in  1874, 
referred  to  this  species,  has  the 
long  neck  and  nearly  the  figure  of  a 
Llama.  With  the  Paleothere  were 
Tapir-like  beasts  of  the  genus  Lophio- 

don,  and  others.  Higher  in  the  series  were  found  the  remains  of  Anoplo- 
theres  and  Xiphodons,  Artiodactyls  related  to  the  Ruminants  in  their  feet, 
but  at  the  same  time  having  some  characters  of  the  Hogs.  The  Xiphodons 
were  of  slender  form  (Fig.  1546).  The  species  were  remarkable  for  having 
the  full  number  of  teeth,  44,  and  the  set  of  teeth  as  even  in  outline  as  in 
Man,  the  eye-tooth  having  nothing  of  the  elongation  which  is  common  in 
brutes  and  is  so  striking  a  part  of  the  armature  of  Hogs  and  Carnivores ; 
and  hence  the  name  Anoplothere,  from  avoTrAos,  unarmed,  and  Orjp.  With  the 
Anoplotheres,  there  were  also  Hog-like  Artiodactyls,  species  of  Chceropotamus 
and  of  other  genera.  The  fauna  included  also  various  Carnivores,  Rodents, 
Bats,  and  an  Opossum.  The  Carnivores  included  a  Wolf,  Canis  Parisiensis, 
the  Weasel-like  Cynodon  Parisiensis ;  and  the  Creodonts,  the  Dog-like  Hyce- 
nodon  dasyuroides,  etc. 

In  the  Miocene  occur  the  earliest  of  Mastodons,  Elephants,  and  the  still 
stranger  Elephant-like  animal,  the  Dinothere,  besides  Paleotheres  and  other 
Tapir-like  beasts,  new  Carnivores,  Monkeys,  Deer,  Antelopes,  and  the 
first  Edentates. 

Fig.  1547  represents,  much  reduced,  the  skull  of  the  Dinothere  (Dino- 
therium  giganteum  Kaup).  The  head  carried  a  trunk,  and  two  tusks,  like 
an  Elephant;  but  the  tusks  were  turned  downward.  There  is  a  mixture 


Xiphodon  gracilis,  as  restored  by  Cuvier. 


CENOZOIC   TIME  —  TERTIARY.  92& 

of  the  characteristics  of  the  Elephant,  Hippopotamus,  Tapir,  and  the  marine 
Manatus  (Dugong),  in  its  skull;  but  its  nearest  relations  are  with  the  Ele- 
phant or  Mastodon.     One  fine  skull  was  dug  up 
at  Eppelsheim  in  Germany ;    and  the  remains  1547> 

have  been  found  also  in  France,  Switzerland,  and 
other  parts  of  Europe,  and  also  in  Sind,  India. 

In  the  Miocene,  Europe  had  its  species  of 
Ant-eater,  the  Macrothei'ium,  which  was  an  Un- 
gulate, related  to  the  later  Chalicotherium. 

The  Pliocene  of  Europe  has  afforded  also 
species  of  the  Baleen  Cetaceans  (Whale-bone 
Whales).  Species  of  the  genus  Cetotherium 
occur  in  the  Pliocene  of  England  and  Belgium, 
and  also,  according  to  Lydekker,  in  the  Miocene 
of  Patagonia,  along  with  Cetaceans  of  other  Dinotherium  giganteum  (x  A). 
genera. 

All  the  Fishes,  Reptiles,  Birds,  and  Mammals  of  the  Tertiary  are  extinct 
species. 

Subdivisions  and  Characteristic  Species. 

Lower  Eocene.  —  (1)  CERNAYSIAN  (=  PUERCO).  — Beds  at  Reims  and  La  Fere  in  the 
adjoining  departments  of  Marne  and  Aisne  in  northern  France.  At  Cernay,  near  Reims, 
occur  the  following  Mammals :  —  MARSUPIAL  :  Neoplagiaulax.  CREODONT  :  Arctocyon, 
Hyodectes,  Heteroborus.  INSECTIVORE  :  Adapisorex.  QUADRUMANA  :  Plesiadapis,  Proto- 
adapis.  There  are  also  the  BIRDS,  Gastornis  Edwardsi,  Eupterornis. 

In  overlying  beds  occur  Hycenodictis,  Proviverra,  Plesiadapis,  with  Teredina 
personata  ;  and  some  sand-beds  afford  Cyrena  cuneiformis,  Melania  inguinata,  Cerithium 
variabile. 

(2)  SUESSONIAN  of  d'Orbigny  (=  Wasatch,  the  Landenian  of  Belgium).  Includes 
the  Thanet  sands  of  the  London  basin  (Thanetian,  of  Lapparent).  Also,  (a)  the  marls 
of  Meudon,  with  (6)  Lignitic  clays,  and  (c)  Plastic  clay,  but  more  marine  in  Belgium,  to 
which  correspond  the  stages  (a)  Maudunian,  (6)  Sparnacian,  and  (c)  Tpresian.  The 
Paniselian  beds  of  Dumont  are  part  of  the  Ypresian. 

IN  ENGLAND. — Thanet  sands. — Pholadomya  cuneata  Sow.,  Cyprina  Morrisii  Sow., 
Corbula  longirostris  Desh.,  Scalaria  Bowerbankii  Morr. 

Woolwich  and  Reading  beds.  —  Cyrena  cuneiformis  Fer.,  C.  tellinella  Fer.,  Melania 
inguinata  Dfr.,  Ostrea  bellovacina  Lam. 

London  Clay  (Island  of  Sheppey,  etc).—  Nautilus  centralis  Sow.,  N.  imperialis  Sow., 
Aturia  ziczac  Bronn,  Belosepia  sepioidea  Blv.,  Valuta  Wetherellii  Sow.,  V.  nodosa 
Sow.,  Aporrhais  Sowerbyi  Mant.,  Cyrena  cuneiformis,  Cryptodon  (Axinus}  angulatus 
Sow.,  Leda  amygdaloides  Sow.,  Pinna  affinis  Sow. 

VERTEBRATES  of  the  London  clay.  — FISHES  AND  REPTILES  :  Tetrapterus  priscus  Ag., 
Pristis  bisulcatus  Ag.,  Lamna  elegans  Ag.,  Palceophis  toliapicus  Owen.  MAMMALS. — 
MARSUPIAL  :  Didelphis.  UNGULATES  :  LopModon,  Miolophus,  Hyracotherium,  Coryphodon. 

In  France,  at  Meudon,  Coryphodon,  Palceonictis,  Phenacodus,  with  Gastornis. 

Middle  and  Upper  Eocene.  —  PARISIAN  (=  the  Bridger  beds).  (1)  The  Calcaire 
grossier  of  Paris  (Lutetian  of  Lapparent)  ;  with  above,  (2)  the  sands  of  Beauchamp, 
France,  etc. ;  Bagshot  sands  of  the  London  Basin,  and  the  Barton  clay  of  the  Hampshire 
Basin,  England  (Bartonian). 


926  HISTORICAL   GEOLOGY. 

IN  THE  BAGSHOT  SANDS,  ENGLAND.  —  Nummulites  levigatus  Lam.,  Cardita  planicosta 
Lam.,'  Pleurotoma  attenuata  Sow.,  Turritella  multisulcata  Lam.,  Conus  deperditus  Brngt., 
Lucina  serrata  Sow. ;  Myliobatis  Edwardsi  Dixon,  Carcharodon  angustidens  Ag.,  Otodus 
obliquus  Ag.,  Galeocerdo  latidens  Ag.,  Lamna  elegans  Ag.  Reptiles,  Palceophis  typhceus 
Owen,  Gavialis  Dixoni  Owen,  Crocodilus  Hastingsice  Owen ;  Mammals,  Dichodon  cuspi- 
datus  Owen,  Lophiodon  minimus  Cuv.,  Microchcerus  erinaceus  Wood,  Paloplotherium 
annectens  Owen. 

Barton  Series.  —  Mitra  scabra  Sow.,  Valuta  ambigua  Lam.,  Typhis  pungens  Morr., 
Valuta  athleta  Sow.,  Terebellum  fusiforme  Lam.,  T.  sopita  Morr.,  Cardita  sulcata  Morr., 
Crassatella  sulcata  Sow.,  Nummulites  variolarius  Morr.  (variety  of  N.  radiatus  Sow.), 
Chama  squamosa  Brand. 

The  CALCAIRE  GROSSIER  contains  many  species  of  Fishes,  and  also  of  other  tribes 
identical  with  those  of  the  Upper  Eocene  of  England. 

Oligocene.  —  LUDIAN  (=  Uinta  beds).  The  Montmartre  gypsiferous  marls  of  Paris, 
Bembridge  and  Headon  beds  of  the  Isle  of  Wight.  TONGRIAN  (  =  White  River  beds; 
Upper  Oligocene,  of  Europe).  Includes  the  Hempstead  beds  of  the  Isle  of  Wight,  the 
Fontainebleau  sandstone,  in  France,  clays  with  Gyrena  convexa,  near  Tongern  in  Belgium, 
the  Lower  marine  Molasse  of  Switzerland.  The  name  Rupelian  is  given  in  Belgium  to 
an  upper  portion  of  the  beds  ;  and  Bolderian  to  still  higher  beds. 

Headon  Series. —  Planorbis  euomphalus  Sow.,  Helix  labyrinthica  Say,  Neritina  con- 
cava  Sow.,  Limncea  caudata  Edw.,  Cerithium  concavum  Desh. ;  Lepidosteus ;  Reptiles, 
Emys,  Trionyx ;  Mammals,  Palceotherium  minus  Cuv.,  Anoplotherium,  Anthracotherium, 
Dichodon,  Dichobune,  Spalacodon,  Hycenodon. 

Bembridge  Series  (120  feet  thick).  —  Cyrena  semistriata  Desh.,  Paludina  lenta  Desh., 
P.  orbicularis  Voltz.,  Melania  turritissima  Forbes,  Cerithium  mutabile  Lam.,  Cyrena 
pulchra  Morr.,  Bulimus  ellipticus  Sow.,  Helix  occlusa  Edw.,  Planorbis  discus  Edw.  ; 
MAMMALS:  Palceotherium  magnum  Cuv.,  P.  medium  Cuv.,  P.  minus  Cuv.,  P.  minimum 
Cuv.,  P.  curium  Cuv.,  P.  crassum  Cuv.,  Anoplotherium  commune  Cuv.,  A.  secundarium 
Cuv.,  Dichobune  cervinum  Owen,  Chceropotamus  Cuvieri  Owen. 

From  the  Montmartre  gypsum  beds  of  France,  and  equivalent  beds,  have  been  obtained 
species  of  the  genera  Palceotherium,  Anoplotherium,  Xiphodon  (X.  gracilis}  ;  the  Carni- 
vores, Hycenodon  (H.  leptorhynchus  Blv.),  Cynodon  Parisiensis  Pomel,  Bats,  and 
Opossum. 

The  Phosphorite  beds  of  Quercy,  referred  to  the  Oligocene,  have  afforded  Palceothe- 
rium, Anoplotherium,  Xiphodon,  Hycenodon,  Cynodictis,  Cebochcerus,  along  with  Amphi- 
tragulus,  Aceratherium,  Necrolemur,  and  others. 

Lapparent  divides  the  Oligocene  into  the  Tongrian  and  Aquitanian  stages ;  and  the 
Tongrian  into  Sannoisian  and  Stampian  substages. 

The  Hempstead  beds  of  England  have  afforde'd  Corbula  pisum,  Cyrena  semistriata 
Desh.,  Cerithium  plicatum,  C.  elegans,  Eissoa  Chastelii,  Paludina  lenta,  Melania  fasciata, 
M.  costata  Sow. ;  the  Mammal,  Hyopotamus  bovinus  Owen. 

Lower  Miocene  (=  John  Day  Beds,  Lower  Miocene,  in  Germany,  etc.).  —  Lacus- 
trine limestone  of  Beauce  and  Meulieres  de  Montmorency,  in  France,  and  limestone  of 
Agenais  in  Aquitania,  southwest  France  ;  Red  Molasse,  Lignitic  Molasse  in  Switzerland. 

1.  MAYENCIAN  (Langhian,  Burdigalian).  —  Freshwater  Molasse  of  Switzerland  ;  beds 
at  Mayence,  Belgium. 

2.  HELVETIAN.  —  Marine  Molasse  of  Switzerland,  Faluns  of  Anjou  with  Ostrea  cras- 
sissima,  etc.,  of  Touraine,  in  western  France,  Molasse  of  the  Superga,  Italy. 

Upper  Miocene. — TORTONIAN. — Marls  with  Helix  Turonensis  in  western  France; 
(Eningen  beds,  Leitha  limestone  near  Vienna,  Blue  marls  of  Tortone  in  Italy.  Above 


CENOZOIC   TIME TERTIARY.  927 

the  Tortonian,  the  stages  Sarmatian  and  Pontiem  are  recognized  in  Dauphine,  Austria, 
and  Italy. 

Some  of  the  Miocene  genera  are  Pliopithecus,  Dryopithecus,  of  Quadrumanes ; 
Machcerodus,  Felis,  Hyceuarctos,  Hycena,  Canis,  Viverra,  Mustela,  of  Carnivores ;  Mas- 
todon (M.  longirostris,  M.  tapiroides  Cuv.,  etc.),  Elephas,  Dinotherium;  Rhinoceros, 
Listriodon,  Sus,  Anchitherium,  Hipparion,  Equus,  Hippopotamus;  Camelopardalis,  Ante- 
lope, Cervus,  of  Ruminants ;  Erinaceus,  Talpa,  of  Insectivores  ;  Halitherium,  Squalodon, 
Physeter,  Delphinus. 

The  Tertiary  Mammals  of  the  Siwalik  Hills,  India,  from  beds  now  referred  to  the 
Pliocene,  include,  besides  Quadrumana,  species  of  Hycenarctos,  Hycena,  Machcerodus, 
Felis,  Canis,  Mustela,  Viverra;  Elephas,  Mastodon,  Rhinoceros,  Hexaprotodon,  Hippo- 
therium,  Equus,  Hippopotamus,  Sus,  Anoplotherium,  Chalicotherium,  Merycopotamus, 
Camelus,  Camelopardalis;  Sivatherium,  Antilope,  Moschus,  Cervus,  Ovis,  Bos;  Dinothe- 
rium; Hystrix;  Enhydriodon.  The  Sivatherium  was  an  elephantine  Stag,  having  four 
horns,  allied  to  the  Deer,  but  larger,  being  in  some  points  between  the  Stags  and  Pachy- 
derms. It  is  supposed  to  have  had  the  bulk  of  an  Elephant,  and  greater  height.  Bos  and 
the  related  genera  probably  occur  nowhere  earlier  than  the  Pliocene.  There  were  also 
Crocodiles  of  large  size,  and  the  great  turtle  Colossochelys  Atlas. 

In  southern  South  America,  the  Santa  Cruz  beds,  which  are  referred  to  the  Miocene, 
afford  species  of  Edentates,  Rodents,  Marsupials,  Nesodon,  Toxodon,  Prototherium, 
Prosqualodon,  Argyrocetus,  Odontoceti,  or  Toothed  Whales,  and  other  species. 

The  following  new  Miocene  species  from  East  Siberia  have  been  described  and  figured 
by  W.  H.  Ball :  Semele  Stimpsoni,  Siphonaria  Penjince,  Conus  Okhotensis,  Cerithium 
cymatophorum,  Diloma  ruderata ;  and  he  has  identified  also  Ostrea  gigas  Thunberg. 
They  occur  in  a  bed  in  the  northeastern  angle  of  the  Okhotsk  Sea,  on  a  small  bay  in  the 
Gulf  of  Penjinsk  containing  a  layer  of  coal.  They  were  brought  from  the  region  in  1855 
by  Wm.  Stimpson,  a  member  of  the  Ringgold  and  Rogers  Exploring  Expedition.  The 
fauna  is  related  to  that  of  the  China  and  South  Japan  seas,  and  indicates,  states  Ball,  a 
change  downward  of  water  temperature  since  the  Miocene  of  30°  to  40°  F. 

Lower  Pliocene.  —  MESSINIAN,  the  Zanclean  beds  in  Italy  of  Seguenza,  and  over  the 
Zancleau  beds,  along  the  Apennines,  Plaisancian  of  Seguenza. 

Upper  Pliocene.  —  ASTIAN. —  Crag  of  Norwich,  etc.,  Eastern  England;  Subapennine 
marls  and  sands  of  beds  of  Val  d'Arno.  In  the  Red  Crag,  Felis  pardoides  Owen, 
Mastodon  Arvernensis  Croizet  &  Jobert  (angustidens  Owen),  Rhinoceros  Schleiermacheri 
Kaup  (incisivus  Cuv.),  Tapirus  priscus  Kaup  (Arvernensis  Croizet  &  Jobert),  Cervus 
anoceros  Kaup.  In  the  Norwich  Crag,  Mastodon  Arvernensis,  M.  longirostris,  M. 
Borsoni,  Elephas  meridionalis,  Cervus  Falconeri,  C.  verticornis. 

Forest  bed  of  Cromer  on  the  east  coast  of  England,  referred  by  many  to  the  Lowest 
Quaternary,  includes,  besides  the  Cave  Bear,  the  Irish  Deer  ;  and  several  modern  species, 
as  the  Beaver,  Wolf,  Fox,  Stag,  Aurochs,  Mole,  Wild  Boar,  Horse ;  also  the  European 
Pliocene  species,  Ursus  Arvernensis,  Cervus  Polignacus  Robert,  Hippopotamus  major  Cuv., 
Rhinoceros  Etruscus,  R.  megarhinus,  Elephas  meridionalis,  E.  antiquus,  Equus  Stenonis, 
and  without  any  remains  of  man.  The  Forest  bed  is  made  Pliocene  in  the  Manuals  of 
Etheridge  and  H.  B.  Woodward,  but  lower  Glacial  by  Geikie  and  others. 

The  Pikermi  Middle  Pliocene  beds  in  Greece  contain  out  of  29  genera  of  Mammals, 
18  that  are  found  also  in  the  Middle  Pliocene  of  the  Siwaliks'of  India;  there  is  the  same 
remarkable  abundance  of  true  Ruminants,  and  among  them,  as  in  the  Siwaliks,  several 
species  of  Giraffidce  and  Antelope;  there  are  at  Pikermi  15  Ruminants  to  1  Pig  and 
1  Chalicotherium,  and  in  the  Siwaliks  37  Ruminants  to  12  other  Artiodactyl  Ungulates 
(Oldham,  Geol  of  India). 


928  HISTORICAL   GEOLOGY. 

GENERAL  OBSERVATIONS  ON  THE  TERTIARY. 
BIOLOGICAL  CHANGES  AND  PROGRESS. 

The  precursors  of  the  Tertiary  Mammals.  —  No  immediate  precursors  of 
the  Tertiary  non-marsupial  or  placental  Mammals,  linking  them  to  the 
Marsupial,  have  yet  been  found  in  any  part  of  the  world,  notwithstanding 
the  occurrence  in  many  regions  over  America  as  well  as  the  other  conti- 
nents of  a  gradual  passage  from  the  Cretaceous  formation  into  the  Tertiary. 
They  are  naturally  supposed  to  have  existed  in  the  later  Cretaceous  over 
the  dry  land  of  eastern  and  western  America ;  but  still  it  is  strange  that 
they  did  not  find  resorts  somewhere  on  the  border  of  the  Cretaceous  seas 
along  with  the  Marsupials.  The  nearest  approach  in  the  Reptilian  type  to 
the  Mammalian  yet  known  was  made  by  the  stupidest  of  the  Dinosaurs^ 
which  had  a  pair  of  Bovine  horns  and  two-pronged  teeth. 

Early  prototypic  character. — Another  strange  fact  is  that  although  the 
Marsupials  of  earlier  time  had  become  variously  specialized,  their  placental 
successors  should  have  had  unspecialized  or  prototype  characteristics,  such  as, 
have  been  described ;  that  there  should  have  been  at  this  time  so  striking  a 
starting  from  what  appears  to  be  a  new  beginning.  The  removal  of  the 
former  mystery  may  also  remove  this.  Moreover,  it  is  to  be  considered  that 
among  the  fossils  of  the  Mesozoic  Marsupials,  remains  of  the  limbs,  or  of  any 
parts  of  the  skeleton  excepting  the  jaws  and  teeth,  are  of  very  rare  occurrence. 

DIVERSITY  OF  EOCENE  MAMMALS.  —  Another  remarkable  fact  is  that  so 
great  a  diversity  of  Mammals,  diversity  in  structure  as  well  as  size,  should 
have  appeared  before  the  Eocene  period  had  passed.  The  prototypic  plant- 
eaters  and  flesh-eaters  of  the  earliest  part,  supposed  to  be  plantigrade  in  feet, 
were  followed,  even  in  the  Wasatch  division  of  the  Lower  Eocene,  by  species. 
of  large,  short-footed  Ungulates,  the  Coryphodonts,  and  in  the  later  Eocene 
huge  Dinocerata,  the  latter  supplied  with  horns  for  attack  and  defense. 
In  the  Eocene,  also,  the  Tapir-like  species  advanced  far  toward,  the  modern 
genera,  Tapirus  and  Rhinoceros.  There  also  appeared  various  species  with 
paired  toes,  in  the  line  of  the  Hogs,  Hippopotamus,  Camel,  so  that  the  type 
of  Artiodactyls,  and  the  types  of  several  of  its  principal  subdivisions,  were 
established.  There  were  also  some  prominent  Eocene  types  of  Rodents  and 
Insectivores.  Further,  the  Quadrumana  of  the  Early  Eocene,  having  the 
typical  number  of  teeth,  44,  were  followed  in  the  Later  Eocene,  by  others, 
in  which  the  number  of  teeth  was  reduced  to  32,  the  final  limit  in  the 
Quadrumana,  and  that  characterizing  Man. 

Moreover,  there  were  several  successions  of  Mammalian  faunas  in  this 
first  period  of  the  North  American  Tertiary,  and  the  species  in  each  of  them 
probably  outnumbered  those  of  Recent  North  America.  The  kinds  found 
fossil  may  have  been  a  fourth  of  all  then  existing  in  the  region,  and 
probably  not  more. 

Loss  of  prototype  characters.  — Very  early  in  the  Eocene,  prototype  charac- 


CENOZOIC   TIME  —  TERTIARY.  929 

ters  began  to  disappear.  The  teeth  had  the  typical  number,  44,  reduced ;  their 
structure  made  more  complex ;  and  their  characters  varied  otherwise  through 
use  and  adaptations  to  different  purposes. 

The  feet  had  the  number  of  digits  reduced  in  most  Ungulates,  but  not  in 
the  Coryphodon  line,  or  in  the  Carnivores,  or  the  Quadrumana,  or  rarely  in  the 
Insectivores  or  Rodents.  Moreover,  the  feet  lost  the  plantigrade  tread  in 
the  Herbivores,  and  Carnivores,  but  not  in  the  Quadrumana,  Insectivores, 
or  Rodents. 

In  most  of  the  larger  species  the  regularity  in  the  carpal  and  tarsal  series 
of  the  feet  gave  way  to  the  oblique  or  alternating  position  of  the  bones 
required  for  firmness  in  running. 

Some  of  the  causes  favoring  change.  —  The  development  of  so  great  a 
diversity  of  Eocene  Vertebrate  structures  is  the  more  remarkable  in  view  of 
the  absence  of  all  evidence  as  to  any  great  physical  or  meteorological  dis- 
turbance to  require  new  adaptations.  No  change  of  climate  is  indicated 
beyond  what  might  have  occasioned  a  feeble  amount  of  migration.  No  evi- 
dence of  disquiet  in  the  earth's  crust  has  been  noted,  excepting  that  relating 
to  the  imperceptible  geosynclinal  movements  over  the  areas  of  the  Eocene 
lakes  attending  the  slow  deposition  of  sediments. 

The  only  sources  of  disquiet  that  can  be  appealed  to  as  causes  of  bio- 
logical change,  are  biological  sources  proceeding  from  the  appetites  or  needs 
or  impulses  of  the  animals.  Of  these  appetites  the  dominant  one,  the  most 
imperative,  the  only  daily  recurring  one,  was  the  demand  for  food.  As 
nearly  half  of  the  Mammals  lived  on  animal  food,  there  was  perpetual  strife 
between  the  stronger  flesh-eaters  and  the  weaker,  and  between  all  flesh-eaters 
and  other  species.  It  would  naturally  have  driven  the  weak  kinds  to  holes, 
or  somewhere  out  of  reach  of  their  enemies,  where  poor  food,  darkness,  and 
other  privations,  would  have  been  unfavorable  to  high  progress.  The  strife, 
moreover,  as  writers  on  the  derivation  of  species  have  illustrated,  would 
have  promoted  fleetness,  cunning,  devices  for  protection,  and  have  favored 
those  changes  in  the  Mammalian  structures  that  would  better  fit  or  accom- 
modate the  species  to  the  new  demands. 

The  evolution  of  the  Horse  through  the  necessity  of  running  to  escape 
from  enemies  has  often  been  set  forth  as  an  example  of  the  effects,  under 
certain  conditions,  of  such  a  cause.  An  animal  of  primitive  Ungulate  type, 
having  the  third  or  middle  toe  the  longest  of  the  five,  raising  itself  on  its 
toes  for  greater  speed  in  running,  and  forcing  itself  forward  naturally  by  its 
longer  toe,  had  this  toe,  as  Eocene  and  Miocene  time  passed,  with  the  bone 
of  the  foot  above  it  (the  metatarsal  and  the  metacarpal)  enlarged  and 
elongated,  while  the  less-used  toes  either  side  dwindled  till  too  short  to  reach 
the  ground ;  and  finally,  through  these  and  other  concurrent  changes,  there 
was  evolved,  a  long-legged  one-toed  animal  —  the  Horse.  It  became  tall  and 
long-legged,  not  only  by  elongating  growth  in  certain  bones,  but  also  through 
the  functional  appropriation  by  the  leg  of  all  of  the  foot  excepting  the 
terminal  hoofed  joint. 

DANA'S  MANUAL  —  59 


$30  HISTORICAL   GEOLOGY. 

For  the  Artiodactyl,  the  theoretical  history  is  the  same,  excepting  that 
-i-  two  toes,  the  third  and  fourth,  were  concerned  instead  of  one  —  the  two 
acting  together  in  dynamical  unison.  An  early  Ungulate  rising  on  these  two 
toes  in  running  in  order  to  make  thus  its  greatest  speed,  the  toes  and  also 
their  metatarsals  and  metacarpals  became  equallv  enlarged  and  alike  elon- 
gated, while  the  less-used  toes  either  side,  the  second  and  fifth,  became  a 
shorter,  weaker  pair  —  as  illustrated  in  the  Hog ;  or,  after  further  change, 
the  dominant  pair  became  still  longer,  while  the  shorter  was  reduced  to  a 
rudimentary  pair  or  to  hoofs,  or  became  wholly  obsolete  excepting  meta- 
carpal  and  metatarsal  splint  bones,  as  in  the  fleeter  Artiodactyls. 

Further:  the  stroke  of  the  foot  demanded,  for  high  speed  and  safety, 
that  there  should  be  little  or  no  rotation  of  the  foot  by  a  movement  of  the 
bones  of  the  lower  leg,  —  that  is,  of  the  radius  and  ulna  of  the  front  pair  and 
the  tibia  and  fibula  of  the  hind  pair,  —  and  consequently  the  ulna  and  fibula 
became  reduced  sometimes  to  splint  bones,  or  united  by  coossification  sever- 
ally to  the  radius  and  tibia ;  and  likewise,  in  the  two-toed  Artiodactyl,  the 
corresponding  two  metatarsals  and  metacarpals,  having  no  movement  between 
them,  became  coossified  into  a  "  cannon  bone." 

There  is  little  that  is  hypothetical  in  the  above  statements,  for  the  suc- 
cessional  lines  and  the  sutures  of  half -finished  coossification  are  fully  illus- 
trated among  the  species.  Modern  surgery  finds  that  bones  at  joints  become 
coossified  by  too  long  confinement  in  splints  without  a  chance  for  movement. 
The  variety  of  four-toed  Artiodactyls  during  the  Tertiary  was  very  large ; 
but  at  present  they  are  confined  to  the  few  of  the  Suillines,  or  the  Hog 
family,  and  the  Hippopotamus  group.  The  two-toed  species,  on  the  contrary, 
or  the  Stags,  Deer,  Cattle,  and  the  like,  are  most  abundant  in  recent  time. 

The  following  considerations  bear  on  the  character  of  the  changes  that 
went  forward  among  the  Mammals.  Of  the  three  divisions  (1)  the  Plant- 
eaters,  (2)  the  Animal-eaters,  (3)  the  Omnivores,  the  last-mentioned, — that 
is,  the  Quadrumana  or  Monkeys,  —  must  have  early  taken  to  the  trees,  as 
their  habits  indicate.  This  was  an  easy  method  of  escaping  enemies.  Being 
strong  in  their  fore  limbs,  they  had  the  trees  and  the  ground,  fruit  and  flesh, 
within  their  range.  For  defense  or  attack  they  needed  no  abnormal  growths, 
such  as  horns ;  and  they  have  been  from  the  first  without  them. 

The  Animal-eaters,  in  their  development,  would  have  divided  according 
to  food  and  habits.  Those  forced  to  take  the  poorest  and  most  abundant 
and  easily  got  of  animal  food,  the  Insectivores,  fos serial  and  skulking  species, 
degenerated,  becoming  small  species,  mostly  remaining  plantigrades,  the 
teeth  in  some  losing  their  differentiation,  in  others  disappearing  altogether. 
The  insects  which  they  ate  needed  no  chewing.  Some  of  them  found  pro- 
tection in  the  substitution  of  spines  for  fur  (the  Hedgehogs),  and  in  the  safe 
but  cowardly  method  of  rolling  into  a  ball  with  spines  out  in  all  directions. 

The  higher  section  of  the  Animal-eaters,  or  the  Carnivores,  living  on  the 
best  of  animal  food,  and  generally  having  to  fight  for  it,  and  always  on  the 
alert,  having  the  fore  limbs  the  stronger  pair,  and  efncient  as  arms  in  secur- 


CENOZOIC    TIME  —  TERTIARY.  931 

Ing  or  holding  food,  and  jaws  armed  with  long  canines,  they,  too,  needed 
no  abnormal  growths  for  defense  or  attack. 

The  larger  Plant-eaters,  who  dared  to  face  the  Carnivores,  at  least  when 
escape  was  not  easy,  whose  legs,  while  good  for  locomotion,  were  of  no  ser- 
vice for  prehension  or  attack,  *ised  themselves  as  battering-rams,  with  the 
head  as  the  striking  et>d  and  the  means  also  of  tossing  away  or  rending  the 
daring  enemy.  Under  the  necessities  of  their  condition,  the  forehead  and 
nose  grew  horns,  and  a  pair  of  teeth  became  elongated  into  tusks.  As  the 
legs,  besides,  were  of  no  service  for  gathering  food,  the  nose,  as  well  as  the 
elongated  canines,  was  sometimes  made  to  serve  for  grubbing ;  and  the  nose 
thus  used  became  elongated,  until  the  Tapir's  nose  could  pull  over  a  tree, 
and  the  Elephant's  serve  as  a  long  agile  arm  of  great  strength  and  wide 
diversity  of  work.  Such  abnormal  growths  are  characteristics  of  Herbivores 
alone.  The  graceful  Horse  is  one  of  the  exceptions  among  Herbivorous 
locomotors,  for  it  finds  its  chief  means  of  attack  in  its  hind  legs,  and  of 
•escape  in  its  fleetness. 

Great  degeneration  also  took  place  among  the  Mammals ;  for  before  the 
•close  of  the  Eocene  there  were  Whales  in  the  seas  —  the  Zeuglodons.  The 
species  is  supposed,  from  its  teeth  and  food,  to  be  a  degenerate  flesh-eating 
species,  which,  for  escape,  took  to  the  water,  where  support  from  limbs 
is  not  needed.  In  this  supporting  element  the  body  became  enormously 
enlarged  and  multiplicate  in  its  vertebral  column,  like  the  Sea-Saurians, 
the  length  being  increased  from  four  or  five  feet  to  70  feet,  and  the  size  of  the 
dorsal  vertebrae  to  a  diameter- of  a  foot  and  a  length  of  a  foot  and  a  half. 
Its  teeth  remained  few,  36 ;  and  the  molars  retained  their  two  roots,  but  the 
distinction  between  molars  and  premolars  was  lost. 

Further:  in  the  Miocene,  as  stated  on  page  912,  Whales  appeared  of 
greater  degeneration  along  two  or  more  lines :  species  appearing  that  were 
multiplicate  in  teeth,  and  in  the  phalanges  of  some  of  the  digits  of  the  fore 
limbs,  as  well  as  in  vertebrse ;  others  that  had  teeth  only  in  one  jaw  and  all 
single-rooted ;  and  still  others  that  had  no  teeth,  but  only  plates  of  whale- 
bone with  unravelled  edges  in  a  huge  mouth  to  strain  out  small  animals  from 
the  sea-water  for  food. 

It  may  be  supposed  that  these  aquatic  animals  became  urosthenic,  like 
Fishes,  because  sculling  with  the  whole  posterior  part  of  the  body  was  their 
best  mode  of  progression ;  that  the  body  became  long  and  almost  indefinite 
in  number  of  vertebrse,  to  secure  greater  force  in  the  sculling  organ ;  that 
the  hind  limbs  disappeared  because  useless ;  and  that,  in  one  branch  of  the 
tribe,  the  teeth  began  to  disappear  altogether  when  the  smaller  swarming  life 
of  some  parts  of  the  ocean  received  into  the  mouth  almost  without  effort, 
began  to  satisfy  appetite.  It  may  also  be  presumed  that  the  whale-bone 
plates,  over  350  in  number,  either  side  of  the  middle  line,  grew  downward 
from  the  palate  just  as  soon  as  they  were  needed ;  but  the  question,  what 
made  them  grow,  remains,  as  in  many  like  cases,  unanswered.  In  the  young 
state  these  Whales  have  rudimentary  teeth.  The  results  were  much  like 


932  HISTORICAL   GEOLOGY. 

those  that  had  before  occurred  in  Reptiles.  It  was  progress  downward 
almost  indefinitely,  but  without  loss  of  the  essential  characteristics  of  a 
Mammal. 

The  above  examples  and  explanations  may  serve  to  illustrate  some  of  the 
methods  by  which  the  modifications  of  species  are  supposed  to  have  taken 
place  without  the  aid  of  physical  catastrophe. 

The  great  diversity  in  the  characters  of  Eocene  Mammals,  wrought  out, 
it  is  believed,  in  such  quiet  times,  teach  this  plainly  —  that  the  first  period 
of  the  Tertiary  was  exceedingly  long,  whatever  may  be  gathered  to  the 
contrary  from  some  persistent  Cretaceous  plants. 

OROGENIC  AND  EPEIROGENIC   MOVEMENTS. 

In  the  opening  of  the  Tertiary  era  geological  history  reaches  the  time 
when,  as  mentioned  under  Dynamical  Geology,  besides  the  making  of  great 
mountain  ranges,  nearly  all  the  mountain  chains  of  the  world  received 
additions  of  many  thousands  of  feet  to  their  heights  and  hundreds  of  thou- 
sands of  square  miles  to  their  areas ;  and  also  when  igneous  eruptions  took 
place  of  extraordinary  extent. 

1.  Orogenic  movements  at  the  dose  of  the  Nummulitic  epoch  of  the  Eocene.  — 
In   Europe,  the  elevation  of  the   Pyrenees,  and  of  some  other  heights  in 
eastern  Europe,  occurred  after  the  marine  Nummulitic  beds  of  the  Eocene 
had  been  deposited.     The  mean  direction  of  the  Pyrenees  is  about  N.  80°  W. 
There  are  large  flexures  and  steep  slopes  on  the  side  toward   France,  but 
less  upturning  and  gentler  slopes  toward  Spain. 

2.  Orogenic  movements  at  the  close  of  the  Miocene.  —  In  North  America 
an  upturning  took  place  at  this  epoch  along  the  coast  region  of  California, 
and  Oregon,  tilting  and,  in   some  cases,  flexing  the  Miocene,  Eocene,  and 
Cretaceous  formations,  5000  feet  or  more  in  thickness,  as  is  proved  by  Mio- 
cene fossils  in  the  upturned  beds  (J.  D.  Whitney).     The  earlier  Jurassic 
strata  are  believed  to  have  been  earlier  upturned  and  metamorphosed,  being, 
of  cotemporaneous  origin  with  the  Sierra  Nevada. 

At  this  epoch  also  the  great  upturning  of  the  Alps  and  Juras  occurred 
briefly  described  on  page  367.  It  gave  to  the  mountains  the  bold  flexures 
of  the  Mesozoic  formations  with  the  overlying  Eocene  and  Miocene,  which 
are  a  remarkable  feature  of  many  of  the  lofty  summits.  The  Apennines,, 
according  to  Stefani,  passed  through  a  crisis  of  upturning  and  flexures  at 
the  close  of  the  Nummulitic  Eocene,  like  the  Pyrenees,  and  also  at  the  close- 
of  the  Miocene,  with  the  Alps. 

The  Himalayas  were,  to  a  large  extent,  beneath  the  sea  during  the 
Nummulitic  epoch,  and  at  least  20,000  feet  lower  than  now  (page  368). 
Either  directly  after  this  epoch,  or  before  the  close  of  the  Miocene,  there 
was  an  upturning  and  flexing  of  the  Nummulitic  and  underlying  Cretaceous 
beds  (down  to  the  top  of  the  Carboniferous)  and  the  commencement  of  the 
final  elevation  of  the  mountain  chain.  According  to  the  Geological  Survey 


CBNOZOIC   TIME  —  TERTIARY.  933 

of  India,  the  beds  above  the  Nummulitic  formation  at  the  top  of  the 
upturned  series  are  probably  Miocene,  as  indicated  by  the  plant  beds,  one 
species,  the  Sabal  major,  ranging  from  Lower  to  Middle  Miocene  in  Europe. 
The  Siwalik  Tertiary  beds  (of  the  Sub-Himalayas),  many  thousand  feet 
thick,  along  the  length  of  the  Himalayas,  which  are  Pliocene  with  probably 
Upper  Miocene  at  top,  rest  on  the  inferior  Mesozoic  and  Paleozoic  rocks 
along  what  appears  to  be  an  enormous  fault-plane.  This  steep  "fault- 
plane,"  as  shown  by  Medlicott,  is  really  an  original  limit  of  deposition,  in 
part  almost  cliff-like,  to  the  north  of  which  the  Siwalik  beds  never  extended. 
These  beds  are,  therefore,  not  included  in  the  disturbed  region.  There 
appears  to  be  doubt  remaining  whether  the  epoch  of  upturning  followed  the 
close  of  the  Nuinmulitic  Eocene  or  that  of  the  Miocene. 

The  mountain  chains  to  the  north  of  the  Himalayas  for  22°  of  latitude 
are  nearly  parallel  to  it,  and  this  has  led  to  the  suggestion  that  all  this  great 
region  in  Asia  was  involved  in  one  system  of  orogenic  movements. 

Epeirogenic  movements  during  the  Tertiary  era.  —  Through  the  Tertiary, 
changes  of  level  went  slowly  forward  by  geanticlinal  bendings  of  the  earth's 
crust  and  slippings  along  old  or  new  fracture  planes,  giving  great  altitude  to 
vast  continental  areas,  and  especially  those  within  800  miles  of  the  sea- 
border,  and  affecting  all  the  continents  alike  with  the  same  stupendous  results. 
The  continuing  of  the  movements  through  all  Tertiary  time,  and  also  beyond 
it,  during  part  of  the  Quaternary,  teaches  that  they  were  extremely  slow  in 
general  progress ;  yet  sudden  slips  of  scores  and  hundreds  of  feet  were 
probably  among  the  events. 

In  the  Kocky  Mountain  region  the  change  was  slight  during  the  Eocene, 
arid  yet  it  was  sufficient  to  modify  the  outlines  and  positions  of  the  Eocene 
lakes.  With  the  close  of  this  period,  the  land  was  so  far  raised  that  the 
Eocene  lakes  were  drained;  but  the  elevation  attained  was  so  small,  as 
Hayden  first  remarked,  that  vast  Miocene  lakes  covered  a  large  part  of  what 
now  constitutes  the  eastern  slopes  of  the  mountains,  and  continued  into  the 
Pliocene.  The  long  continuance  of  the  lakes  indicates  not  only  slowness  of 
emergence,  but  also  that  the  movements  were  interrupted  through  long 
intervals.  The  western  margin  of  the  Nebraska  lacustrine  beds  is  3500  feet 
above  the  level  of  the  eastern,  the  former  having  a  height  of  about  6000  feet 
and  the  latter  of  2000  feet.  This  is  proof  that  the  elevation  of  the  moun- 
tains went  on  through  the  Pliocene,  for  the  rise  to  the  westward  could  not 
have  made  much  progress  in  the  Miocene  without  drying  up  the  lake. 

The  height  which  the  Eocky  Mountains  had  reached  by  this  change  of 
level  is  not  ascertained.  This  much  is  known:  (1)  that  the  Cretaceous  areas 
were  originally  at  or  near  the  sea  level ;  and  (2)  that  within  the  area  of  the 
United  States  the  present  height  of  the  upper  beds  is  now,  in  part,  13,000 
feet.  Moreover,  the  corresponding  height  in  central  Mexico  is  10,000  feet, 
and  in  British  America,  toward  the  Arctic  seas,  4000  feet. 

During  the  progress  of  these  changes  over  western  North  America  there 
were  also,  according  to  Gilbert,  Powell,  L^Conte,  and  others,  faults  along 


934  HISTORICAL   GEOLOGY. 

fracture-planes  thousands  of  feet  in  displacement  in  the  mountain  ranges  of 
the  Great  Basin,  the  High  Plateaus  of  Utah,  the  Wasatch  Mountains,  and 
the  Sierra  Nevada. 

Through  a  study  of  the  river  systems  of  the  Sierra  Nevada,  it  has  been 
proved  by  LeConte  (1886)  that  a  great  elevation  of  the  Sierra  took  place  at 
or  near  the  close  of  the  Pliocene.  The  drainage  of  the  Sierra  is  chiefly  to 
the  westward,  the  eastern  front  being  very  steep.  Whitney  describes  in  his 
Keport  (1865)  the  facts  respecting  an  early  system  of  valleys  having  been 
covered  up  and  obliterated  by  basaltic  eruptions,  and  the  new  and  much 
deeper  system  of  subsequent  time  (page  300).  He  illustrates  also,  by  a 
plate  in  his  work  on  the  Auriferous  Gravels  (1880),  the  difference  in  the 
depth  of  erosion  of  the  two  systems,  the  earlier  that  occupied  all  Cretaceous 
and  Tertiary  time,  and  the  later,  of  subsequent  time  after  the  eruptions. 
In  view  of  these  and  related  facts,  LeConte  urges  that  the  deeper  erosion 
by  the  existing  streams,  although  their  time  of  work  was  short  compared 
with  that  of  the  earlier  system  which  existed  through  the  Cretaceous  and 
Tertiary,  proves  that  a  great  elevation  of  the  Sierra  Nevada,  increasing  the 
fluvial  denuding  power,  took  place  soon  after  the  Pliocene ;  and  that  this 
was  accomplished  by  a  rise  along  a  fault-plane  having  the  course  of  the 
steep  eastern  front  of  the  range.  It  is  to  be  remarked  that  the  Glacial  period 
followed  the  Pliocene;  and  its  glaciers  and  abundant  precipitation  would 
account  for  part  of  the  profound  denudation  of  the  later  rivers.  But  this 
fact  does  not  invalidate  seriously  the  conclusions.  It  is  sustained  through 
additional  facts  by  other  geologists,  including  Lindgren  and  Diller. 

The  eastern  border  of  the  continent  underwent  only  small  changes.  At 
the  close  of  the  Eocene  some  modification  of  the  surface  occurred  within  the 
Mexican  Gulf  which  put  an  end  to  the  deposition  of  true  marine  beds  along 
its  northern  beds  west  of  Florida.  The  only  Miocene  beds  recognized  are  of 
fresh-water  or  brackish-water  origin.  With  the  close  of  the  Tertiary,  and 
probably  before  the  Pliocene  had  fully  passed,  elevatory  movements  occurred 
which  raised  the  Tertiary  of  the  Atlantic  border  about  100  feet,  and  that  of 
the  Gulf  border  not  much  more,  except  along  a  region  in  Georgia,  and  the 
border  of  Alabama  in  a  line  with  the  Peninsula  of  Florida,  where  the  height 
is  300  to  400  feet  above  sea  level.  A  Florida  axis  of  elevation  is  indicated 
by  it.  On  Long  Island,  Martha's  Vineyard,  and  other  islands  south  of  New 
England,  occur  upturned  beds  of  the  Cretaceous  or  Cretaceous  and  Tertiary, 
indicating  orogenic  movements  before  the  Quaternary.  See  further,  page  1021. 

The  elevation  of  the  Atlantic  border  may  have  been  part  of  a  greater 
change  which  affected  also  the  whole  of  the  Appalachian  region;  but  no  posi- 
tive evidence  of  this  is  yet  obtained. 

What  was  the  total  gain  in  mass  through  the  great  Tertiary  elevation  of 
the  North  American  continent  ?  On  this  point  little  is  known  with  regarcl 
to  its  eastern  half,  but  the  western  affords  available  facts. 

With  the  opening  of  the  Tertiary  the  larger  part  of  the  western  half  of  the 
United  States  was  at  the  water's  level  from  the  eastern  foot  of  the  Sierra  Nevada 


CENOZOIC   TIME  —  TERTIARY.  935 

near  the  meridian  of  120°  to  the  meridian  of  97°,  or  through  a  breadth  of  23°, 
or  nearly  1500  miles.  The  higher  emerged  peaks  of  the  Bocky  Mountain 
region  were  perhaps  4000  or  5000  feet  out  of  water ;  the  Sierra  Nevada,  3000 
to  4000  feet.  Many  peaks  have  Cretaceous  rocks  at  a  high  level ;  one,  Slaty 
Peak,  in  Colorado,  at  13,000  feet,  and  this  is  supposed  to  have  lost  3000  feet  of 
Upper  Cretaceous  by  denudation.  The  floor  of  the  Great  Basin  was  probably 
at  a  height  of  1000  feet  and  less,  and  its  ridges  2000  to  4000  above  sea  level. 
Almost  all  the  rest  of  the  surface  was  near  the  sea  level  or  below  it.  The 
geanticline  added  at  least  13,000  to  the  height  of  the  summit  region ;  of  cen- 
tral Nebraska,  3000  feet  (taking  only  present  altitudes),  and  of  western,  5000 
to  6000  feet;  of  Colorado,  east  of  the  Front  Eange,  6000  to  7000  feet;  of 
central  Mexico,  at  least  10,000  feet ;  of  the  Sierra  Nevada,  10,000,  a  third  of 
it  probably  through  the  general  geosynclinal  movement,  and  the  rest  through 
one  or  more  faults ;  and  so  on.  The  average  elevation  of  western  North 
America  was  certainly  tripled.  This  would  make  the  increase  of  mass  at 
least  10  times.  But,  as  a  large  part  was  a  total  gain,  since  it  rose  from  the 
sea  level,  the  amount  probably  much  exceeded  this ;  12  or  15  times  may  be 
nearer  the  fact.  Supposing  no  addition  in  the  eastern  half  except  that  of 
the  Cretaceous  and  Tertiary  sea  border,  the  gain  in  mass  for  the  whole  con- 
tinent would  be  over  six  times. 

It  is  to  be  admitted  that  the  present  elevation  cannot  in  any  region  be  a 
correct  measure  of  the  actual  height  at  the  close  of  the  Tertiary.  It  is  safe 
to  say  only  that  it  is  the  final  elevation  after  denudation  and  such  Quater- 
nary oscillations  as  may  have  since  occurred.  The  mean  height  may  be 
much  less  now  than  it  was  at  the  close  of  the  Tertiary. 

In  South  America,  the  region  of  the  Andes  through  the  length  of  the  con- 
tinent underwent  at  the  same  time  an  elevation  of  many  thousands  of  feet. 
In  Ecuador,  the  Upper  Cretaceous  forms  most  of  the  peaks  of  the  eastern 
Andes,  and  has  a  height  in  some  of  the  ridges  of  6000  meters  (19,686  feet)  ; 
in  Peru,  northeast  of  Lima  in  111°  S.,  near  the  Pass  of  Antaranga,  a  height 
of  4803  meters  (15,754  feet)  ;  in  the  Province  of  Huarnachuco,  2000  to 
5000  meters ;  in  12°  S.,  between  Pachachaca  and  Jauja,  the  Gault,  at  5000 
meters  (16,405  feet). 

In  Haiti,  according  to  Gabb,  the  Miocene  has  an  elevation  of  200  to  2000  feet ;  and 
a  sea-border  of  limestone,  a  height  of  170  feet  and  less.  In  Jamaica  there  are  2000  feet  or 
more  of  white  limestone,  and  the  rock  covers  six  sevenths  of  the  area  of  the  island.  A 
yellow  limestone  below  on  Jamaica  is  Miocene  ;  and  the  thick  white  limestones  of  Jamaica 
and  Santo  Domingo  as  well  as  of  Cuba  are  probably  of  Tertiary  origin,  if  not  partly  of 
Quaternary. 

On  the  Barbados,  there  is  an  oceanic  deposit  consisting  of  a  score  or  two  of  feet  of 
calcareous  earthy  material,  largely  made  of  Globigerinse,  overlaid  in  some  places  by  100  to 
130  feet  of  siliceous  Radiolarian  earth,  and  above  this  other  calcareous  and  pumiceous 
beds,  with  red  clays  100  feet  or  'more ;  and  these  beds  underlie  the  elevated  coral-reef 
rock  of  the  island  from  the  seashore  to  a  height  of  800  to  900  feet.  They  are  regarded 
by  Jukes-Browne  and  Harrison  (1891,  1892)  as  probably  Pliocene,  and  as  evidence  of  a 
Pliocene  subsidence  of  2000  to  3000  fathoms,  or  to  such  depths  as  now  afford  similar 


936  HISTORICAL   GEOLOGY. 

Kadiolarian  earths.  The  Barbados  are  outside  of  the  outermost  range  of  islands ;  and 
whatever  changes  of  level  they  have  experienced  may  not  have  affected  the  Caribbean  Sea. 
At  present  the  bottom  of  this  sea  is  made  of  Globigerina  and  not  of  Eadiolarian  earth. 
Kadiolarian  deposits  occur  also  on  Haiti,  Jamaica,  and  Cuba ;  but  they  have  less  extent 
and  are  less  decisive  as  to  change  of  level. 

Whether  the  following  changes  of  level  were  epeirogenic  or  not  is  undecided. 

Over  Europe  and  Asia  the  same  elevation  of  the  land  over  extensive  areas 
was  in  progress,  especially  during  the  Pliocene.  Europe  was  much  changed 
in  elevation  cotemporaneously  with  the  disturbance  in  the  Alps ;  and  "  by 
the  close  of  the  Pliocene  all  its  main  features  had  come  into  existence."  The 
Alps  were  carried  up  probably  12,000  feet  or  more,  and  the  Pyrenees  over 
10,000  feet. 

The  Himalayan  chain,  a  region  of  upturning  at  the  close  of  the  Miocene 
(if  not  before,  at  the  close  of  the  marine,  Nummulitie  epoch),  when  20,000 
feet  lower  than  now,  began  afterward,  or  simultaneously,  its  slow  emergence 
and  attained  its  present  level  according  to  Blanf  ord  by  the  end  of  the  Pliocene 
or  in  the  early  Quaternary.  The  Tertiary  beds  of  the  Sub-Himalayas,  or  the 
Siwalik  Hills,  which  are  chiefly  freshwater  Pliocene  and  contain  the  remains 
of  the  Fauna  Antiqua  Sivalensis,  were  laid  down  during  the  progress  of  the 
uplift.  During  all  this  Himalayan  elevation,  peninsular  India  underwent 
little  change. 

Blanford  derives  additional  evidence  as  to  the  remoteness  of  the  time 
of  the  uplift,  from  the  existing  Mammalian  fauna  of  Tibet.  Out  of  43  species 
of  Mammals  in  Tibet,  pertaining  to  26  genera,  27  species  and  4  genera  are 
not  known  out  of  Tibet.  Out  of  16  species  of  Rodents,  only  one  is  not 
purely  Tibetan.  The  various  facts  accord  with  the  view  that  the  elevation 
of  the  Himalaya  E-ange  commenced  early  in  the  Tertiary. 

During  the  early  Eocene,  as  well  as  the  Cretaceous  period,  the  British  Channel  was 
crossed  by  an  Interior  basin,  perhaps  having,  as  Jukes-Browne  suggests  (1892),  a  range 
of  land  over  the  western  part,  uniting  Brittany  to  Cornwall.  But  in  the  Miocene,  on  the 
same  authority,  even  the  area  of  the  Eocene  Anglo-Parisian  basin  had  become  dry  land  ; 
and  in  the  Pliocene,  ridges  were  formed  crossing  the  Channel  from  northwest  to  southeast, 
as  the  Weald  Axis,  the  Portsdown,  the  Purbeck  corresponding  to  the  axis  of  Artois, 
Bresle,  and  Bray  to  the  south.  Only  in  the  Middle  Quaternary,  after  a  phase  in  which  a 
passage  extended  across  from  below  Dover  and  Brighton  on  the  north  to  the  Province  of 
Calais  in  France,  did  the  Channel  secure  its  place  through  a  general  subsidence. 

"  Thus,  throughout  the  Tertiary  era,  the  continents  of  Europe  and  Asia, 
as  well  as  America,  were  making  progress  in  their  bolder  surface  features, 
as  well  as  in  the  extent  of  dry  land.  The  evidence  is  sufficient  to  show  that, 
wnen  the  period  ended,  the  continents  had  in  general  their  mountains  raised 
to  their  full  height."  The  evidence  is  stronger  now  than  it  was,  more  than 
30  years  since,  wher  those  words  were  written. 

Geosynclinal  movements  over  the  oceanic  basin  —  the  "  Coral  Island  sub- 
sidence"—  That  there  were  profound  geosynclhies  over  the  oceanic  basins 
during  the  later  Tertiary  and  early  Quaternary  is  put  beyond  question  by 


CENOZOIC    TIME  —  TERTIARY.  937 

the  fact  of  the  great  continental  elevations  of  the  same  time.  The  Coral 
Island  subsidence,  announced  by  Darwin  in  1839,  recognized  such  geosynclines ; 
and  they  were  long  since  set  forth  by  Dana  as  the  counterpart  of  the  conti- 
nental movements.  The  subsidence  is  thus  a  real  event  in  geological  history ; 
and  if  marvelous,  equally  so  is  that  of  the  world's  so  recent  elevations. 

"  Gondwana-Land,"  connecting  India  with  southern  Africa  (page  737), 
continued  to  exist,  according  to  Oldham  (1894),  from  the  Carboniferous 
period  throughout  Mesozoic  time,  and  "  sank  beneath  the  sea  in  the  Tertiary 
•era,"  leaving  some  volcanic  and  coral  islands  in  its  course,  including  to  the 
northward  the  sunken  atoll  of  the  Chagos  bank.  The  extension  of  "  Gond- 
wana-Land" over  the  Indian  Ocean  is  not  here  in  view,  because  it  is  not 
loelieved  to  have  ever  been  a  fact. 

A  paper  by  Haddon,  Sollas,  and  Cole  (E.  Irish  Acad.,  1894),  after  men- 
tioning the  observation  of  Jukes  that  the  eastern  mountain  range  of  Aus- 
tralia, extending  for  35°  of  latitude  from  Tasmania  to  the  northern  cape, 
•Cape  York,  is  continued  in  islands  across  Torres  Strait  to  New  Guinea,  and 
describing  the  straits  and  the  lands  beyond,  concludes  that  this  southern 
continent  lost  its  border  lands  of  New  Zealand,  New  Caledonia,  and  New 
Guinea  and  the  intermediate  islands  "possibly  during  the  great  Alpine  and 
Himalayan  revolutions  "  of  the  Tertiary  period. 

Igneous  eruptions  during  the  Tertiary.  —  An  eruptive  period  in  the 
earth's  history  commenced  in  the  Later  Cretaceous  (page  875)  and  passed 
its  maximum  in  the  course  of  the  Miocene.  Eruptions  through  fissures  cov- 
ered vast  areas  of  the  Pacific  slope  with  igneous  rocks,  and  volcanic  erup- 
tions made  great  volcanic  cones,  which  added  largely  to  the  outflows  and 
ejections.  The  eruptions  continued  through  the  Pliocene,  and  some  of  the 
cones  are  not  yet  extinct.  The  loftiest  of  the  volcanoes  are  situated  along 
the  Coast  region,  from  Washington  to  northern  California,  the  heights  vary- 
ing from  10,400  to  14,500;  and  those  farther  south  along  a  belt  through 
Mexico  — the  highest  three,  Orizaba  18,200  fee$,  Popocatapetl  17,500  feet, 
and  Ixtaccituatl  16,770  —  are  probably  of  like  Miocene  origin. 

Some  of  the  regions  of  fissure  eruptions  have  been  already  described. 
South  of  Lassen's  Peak,  in  northern  California,  the  southernmost  of  the 
cones  of  the  Pacific  border,  the  region  of  the  Sierra  Nevada  had  its  outflows 
of  broad  streams  of  basalt  from  fissures  which  were  later  but  up  into  Table 
Mountains ;  and  similar  floods  occurred  over  Nevada,  New  Mexico,  and 
Arizona. 

The  higher  western  slopes  and  summit  region  of  the  Rocky  Mountains 
also  had  their  cones.  The  Yellowstone  National  Park  and  its  vicinity  was 
one  of  the  volcanic  centers.  Electric  Peak  and  Sepulchre  Mountain  are  two 
denuded  cones  in  the  Park,  as  described  by  Iddings ;  Emigrant  Peak,  on  the 
Yellowstone,  16  miles  north  of  the  boundary,  is  another,  where  dacyte  and 
quartzose  porphyry  are  the  igneous  rocks ;  Haystack  Mountain,  12  miles 
north  of  the  east  corner  of  the  Park,  is  another,  its  cone  consisting  of  gabbro 
and  dioryte ;  and  another  stands  just  east  of  the  east  corner  of  the  Park, 


938  HISTORICAL  GEOLOGY. 

which  is  like  the  last  in  its  rocks.  Iddings  refers  these  cones  to  the  early 
Tertiary.  He  states  that  after  a  long  period  of  eruption  of  acidic  andesytes^ 
basic  andesytes  and  basalts  were  ejected ;  and  after  these  had  been  much 
denuded,  the  great  outflow  of  rhyolyte  took  place,  forming  the  Park  plateau ; 
and  that  finally  the  basalt  was  poured  forth  that  extends  widely  over  the 
Snake  River  plains  in  Idaho. 

Igneous  eruptions  occurred  through  all  the  successive  geological  ages. 
But  at  no  time  in  American  history  since  the  Archaean,  have  they  approached 
in  extent  those  of  the  Later  Cretaceous  and  Tertiary  periods.  It  was  a  time 
of  pouring  from  fissures  and  of  the  birth  of  volcanoes,  as  never  before. 

It  is  not  yet  certain  that  a  volcano  ever  existed  on  the  continent  of  North  America^ 
before  the  Cretaceous  period ;  for  the  published  facts  relating  to  supposed  or  alleged 
volcanic  eruptions  in  the  course  of  the  Paleozoic  ages  are  as  well  explained  on  the  suppo- 
sition of  outflows  from  fissures  and  tufa  ejections  under  submarine  conditions  ;  and  none 
of  the  accounts  present  evidence  of  the  former  existence  of  a  volcanic  cone,  that  is,  of 
an  elevation  pericentric  in  structure  made  by  igneous  ejections.  Such  cones  in  the 
tropical  Pacific  are  now  encircled  by  coral  reefs  as  well  as  beds  of  detritus,  and  are  thus 
in  process  of  burial ;  and  so  they  might  have  been  buried  by  limestone  and  other  strata,  if 
an  actual  fact  in  Paleozoic  North  America. 

During  the  Archaean,  to  its  end,  igneous  ejections  were  on  a  vast  scale.  Even  after 
the  cooling  had  so  far  advanced  that  the  sedimentary  series  in  progress  of  deposition 
attained  a  thickness  of  many  thousands  of  feet  before  a  crisis  of  upturning  and  meta- 
morphism  occurred,  the  heat  from  below,  which  was  added  to  the  heat  of  a  dynamical 
source  to  produce  the  metarnorphism,  was  so  far  the  greater  of  the  two  that  fusion  of  the 
lower  beds  would  have  generally  taken  place ;  and,  as  a  consequence,  great  effusions  of 
the  melted  rock  through  the  overlying  and  much  broken  metamorphic  beds,  should  have 
occurred  in  true  bathylithic  style,  as  the  facts  attest.  But  there  is  no  evidence  that  they 
ever  made  Archaean  volcanic  cones.  Archaean  conditions  gradually  declined  as  Paleozoic 
time  was  passing,  and  so  also  did  the  power  of  making  bathyliths.  Later  came  the 
power,  not  merely  of  eruption  through  fissures,  which  has  always  existed,  but  also  that 
of  producing  lofty  volcanic  cones. 

-  The  volcanoes  also  of  the  Andes  are  supposed  to  be  chiefly  of  Tertiary 
origin.  In  Europe  "  the  grandest  volcanic  phenomena  were  those  of  Oligo- 
cene  (Lower  Miocene)  times,  to  this  date  belonging  the  basalts  of  Antrim, 
Mull,  Skye,  the  Faroe  Islands,  and  the  older  series  of  volcanic  rocks  in 
Ireland"  (Geikie).  The  volcanic  eruptions  of  Auvergne,  the  Eifel,  and  of 
Italy,  Bohemia,  and  Hungary  are  referred  mostly  to  the  Tertiary.  Asia,  if 
the  ranges  of  islands  off  its  eastern  and  southern  coasts  are  excluded,  is 
peculiarly  free  from  volcanoes.  But  the  outflow  of  the  Deccan  trap  in 
peninsular  India,  200,000  square  miles  in  area,  was  an  event  of  the  early 
Tertiary,  and  has  been  supposed  to  have  occurred  when  the  rising  of  the 
Himalayas  began. 

The  concurrence  during  the  era  from  the  Later  Cretaceous  to  the  close  of 
the  Tertiary  of  the  most  extensive  erogenic  work  in  the  world's  history,  of 
the  chief  part  of  its  continental  elevation,  and  unprecedented  igneous  erup- 
tions, came  when  the  earth's  crust  had  reached  a  cooled  condition  that  took 
all  past  time  up;  to  the  present  era  for  its  production.  The  inquiry  thence 


CENOZOIC   TIME  —  TERTIARY. 

arises  whether  these  events  are  not  in  some  way  a  consequence  of  the  con- 
dition of  the  crust  tljen  for  the  first  time  reached.  The  conclusion  has  been 
before  stated;  it  is  here  announced  in  its  place  in  geological  history. 

CLIMATE. 

The  climate  of  the  United  States,  even  the  northern,  during  the  early 
Tertiary,  was  at  least  warm-temperate,  as  indicated  by  the  fossil  plants. 

There  is  evidence,  as  Asa  Gray  has  remarked  (1859,  1872),  from  the  dis- 
tribution of  Tertiary  plants  in  the  Arctic,  made  known  by  Heer  and  others,, 
and  their  relation  to  similar  kinds  in  the  eastern  United  States  and  in  Asia, 
that  the  northern  parts  of  the  continents  of  America,  Asia,  and  Europe  were,. 
during  that  age,  under  a  nearly  common  forest  vegetation,  with  a  compara- 
tively moderate  climate.  The  genus  Sequoia,  of  California,  has  its  species, 
(as  Heer  has  shown)  in  the  Eocene  of  Greenland,  Arctic  America,  Iceland, 
Spitzbergen,  northern  Europe ;  and  one  Greenland  species  is  very  near  the 
great  Calif  ornian  S.  gigantea;  and  these  were  successors  to  Arctic  Cretaceous 
species.  There  were  two  species  of  Libocedrus  in  the  Spitzbergen  Miocene 
(Heer)  ;  and  one  (L.  decurrens  Heer)  now  lives  with  the  Redwoods  of  Cali- 
fornia, while  the  other  occurs  in  the  Andes  of  Chile.  Gray  adds  that  the 
common  Taxodium,  or  Cypress,  of  the  Southern  States,  occurs  fossil  in  the 
Miocene  of  Spitzbergen,  Greenland,  and  Alaska  as  well  as  Europe,  and  also,, 
according  to  Lesquereux,  in  the  Rocky  Mountain  Miocene.  The  Arctic 
Miocene  is  now  made  by  Dawson  and  others  probably  Eocene  in  age. 

Europe  evidently  passed  through  a  series  of  changes  in  its  climate,  from 
tropical  to  temperate.  According  to  Von  Ettingshausen,  the  Eocene  flora  of 
the  Tyrol  indicates  a  mean  temperature  between  74°  and  81°  F. ;  and  the-, 
species  are  largely  Australian  in  character.  The  numerous  Palms  in  England, 
at  the  same  period,  indicate  a  climate  but  little  cooler. 

The  Miocene  flora  of  the  vicinity  of  Vienna  the  same  author  pronounces 
to  be  subtropical,  or  to  correspond  to  a  temperature  between  68°  and  79°  F. ; 
it  most  resembles  that  of  subtropical  America.  Farther  north  in  Europe, 
the  flora  indicates  the  warm-temperate  climate  characterizing  the  North 
American  Tertiary ;  and  it  is  also  prominently  North  American  in  its  types. 
In  the  Pliocene,  the  climate  was  cooler  still,  and  approximated  to  that  of 
the  existing  world. 

The  North  American  feature  of  the  Miocene  forests  of  Europe  was  proba- 
bly owing  to  migration  from  America  through  the  Arctic  regions,  and  not 
from  Europe ;  for  a  number  of  the  European  species,  as  shown  by  Lesque- 
reux  existed  already  in  the  American  Laramie  and  Eocene.  The  Australian 
feature  also  may  have  been  a  result  of  migration,  but  from  the  opposite 
direction.  The  Indian  Ocean  currents  favor  migration  northward,  along  the 
borders  of  Asia,  and  not  that  in  the  opposite  direction. 

What  was  the  temperature  of  North  America  and  the  other  continents 
at  the  close  of  the  Tertiary,  as  a  consequence  of  the  addition  of  thousands  of 
feet,  and  in  some  regions,  of  tens  of  thousands,  to  the  height  of  the  land,  is, 
to  be  learned  from  the  events  of  the  following  era,  the  Quaternary. 


940  HISTORICAL   GEOLOGY. 


QUATERNARY  ERA,   OR  ERA   OF  MAN. 

Hitherto,  along  the  ages,  to  the  close  of  the  Tertiary  period,  the  conti- 
nent of  North  America  had  been  extending  its  foundations  and  dry  land 
southward  to  the  Gulf,  southeastward  to  the  Atlantic,  and  southwestward  to 
the  Pacific,  chiefly  through  marine  depositions.  The  scene  of  prominent 
action  now  changes.  The  Quaternary  phenomena  are  mainly  those  that 
pertain  to  the  continental  surface  ;  and  this  general  fact  is  true  for  all  the  y 
continents,  north  and  south.  Through  the  making  of  the  great  mountain- 
ranges  in  the  era  just  passed,  and  the  raising  of  them  to  icy  altitudes,  and 
by  the  growth  of  the  continents  to  their  full  limits,  the  water-power  of  the 
world  had  been  vastly  increased,  and  this  was  the  chief  working  agency. 

Rivers  had  become  of  continental  extent,  and  glaciers  had  gathered  about 
the  loftier  mountains.  These  agencies,  so  eminently  characteristic  of  the 
new  era,  were  the  means  of  finishing  off  the  earth's  physical  arrangements. 

The  Quaternary  era  opens  with  a  glacial  period.  "The  existence  at  this 
time  of  an  epoch  of  unusual  cold  was  a  natural  sequence  to  the  vast  amount 
of  elevation  and  mountain-making  that  had  been  going  on  in  the  Tertiary 
over  all  the  continents ;  for  this  upward  movement  would  necessarily  have 
resulted  in  increasingly  cold  climates  over  the  earth."  (D.,  1881.) 

The  following  are  the  periods  of  the  Quaternary :  — 

3.  RECENT  PERIOD. — A  moderate  elevation  of  the  land  where  depressed  in 
the  preceding  period.  Mammals  of  existing  species. 

2.  CHAMPLAIN  PERIOD.  —  Depression  of  lands  that  were  glaciated  in  the 
Glacial  period;  amelioration  of  climates;  final  disappearance  of  the 
ice ;  great  river  floods  and  lakes,  and  fluvial  and  lacustrine  deposits. 
Mammals  of  the  warm  temperate  zone  over  parts  of  the  previously 
glaciated  regions,  their  species  largely  extinct. 

1.  GLACIAL  PERIOD. — Increased  elevation  of  the  land  over  wide  regions  in 
higher  latitudes ;  climate  in  these  latitudes  of  low  temperature  and 
abundant  precipitation,  and  consequently,  the  production  of  glaciers, 
and  a  wide-spread  glaciation  of  the  frigid  lands,  with  the  exclusion  of 
all  life  except  that  of  icy  regions. 

The  Glacial  and  Champlain  periods  were  united  by  Lyell,  in  his  later 
works,  Tinder  the  general  name  of  the  PLEISTOCENE  ;  and  thus  the  Quaternary 
era  —  or  the  Post-Tertiary,  as  he  named  it  —  was  divided  into  the  PLEISTO- 
CENE and  RECENT  periods.  The  term  Pleistocene  is  used  beyond  in  this 
sense. 

Lyell  used  the  term  Post-  Tertiary  for  the  formations  subsequent  to  the  Tertiary,  and 
through  many  editions  of  his  works  divided  it  into  Post-Pliocene  and  Recent.  In  the  first 
edition  of  his  Principles  of  Geology,  published  in  1830-33,  the  Tertiary  was  followed 
.simply  by  the  division  Recent;  and  the  subjects  of  the  Drift  and  Cave  animals  were 


CENOZOIC   TIME  —  QUATERNARY.  941 

included  under  his  second  division  of  the  Pliocene,  called  Newer  Pliocene.  In  1839,  he 
proposed  to  substitute  Pleistocene  for  Newer  Pliocene,  as  a  fourth  division  of  the  Tertiary, 
characterized  by  having  about  95  per  cent  of  the  shells  those  of  living  species  —  a  larger 
proportion,  as  the  name  implies,  than  in  the  earlier  part  of  the  Pliocene.  But  the  new 
name,  as  he  states,  was  used  by  E.  Forbes  in  1846  and  others  for  the  Post-Pliocene  instead 
of  the  Newer  Pliocene,  and  he  withdrew  it.  The  perverted  use  of  the  term  was  partly 
owing  to  his  retaining  Glacial  and  related  topics  under  the  Newer  Pliocene  —  an  arrange- 
ment which  was  continued  into  the  5th  edition  of  his  Manual  of  Elementary  Geology, 
published  in  1855.  This  was  later  changed.  But  in  the  4th  edition  of  the  Antiquity  of 
Man  (1873)  Pleistocene  was  finally  adopted  as  a  substitute  for  Post-Pliocene. 

The  term  Quaternary  was  used  by  Reboul,  of  France,  in  his  work  La  Geologic  de  la 
Periode  Quaternaire,  8vo.,  1833. 

The  division  of  the  Post-Tertiary  or  Quaternary  into  the  three  periods  mentioned 
above  was  presented  by  the  Author  in  his  address  on  "American  Geological  History" 
before  the  American  Association,  in  August,  1855.  (Amer.  Jour.  Sc.,  xxii.,  305,  1856.) 
The  names  for  these  subdivisions  then  proposed  were  the  Glacial,  an  epoch  of  elevation  ; 
the  Laurentian,  an  epoch  of  depression  ;  and  the  Terrace,  an  epoch  of  moderate  elevation. 
In  the  first  edition  of  this  Geology  (1863),  the  terms  adopted  were  Glacial,  Champlain, 
and  Terrace. 

The  two  earlier  periods,  the  Glacial  and  Champlain,  have  their  more 
prominent  characteristics  displayed  almost  solely  over  high-latitude  regions. 
They  are  not  represented  in  tropical  latitudes,  or  in  warm  temperate 
latitudes  south  of  the  parallel  of  35°,  except  locally  about  regions  of  lofty 
mountains.  Moreover,  deposits,  like  those  of  the  Champlain  period,  were 
forming  through  the  Glacial  period  along  the  southern  border  of  the  ice- 
sheet,  owing  to  the  melting  that  was  going  on,  and  the  streams  that  were 
thereby  made,  especially  in  -the  summers,  and  still  more  largely  during 
temporary  relaxations  of  the  extreme  cold.  Further,  the  Mammals  of 
temperate  climates  that  spread  northward  over  the  previously  glaciated 
area  when  the  Champlain  period  opened,  probably  were  all  in  existence 
during  the  middle  and  later  parts  of  the  Glacial  period,  after  the  epoch  of 
extremest  cold  and  maximum  extension  of  the  ice  had  passed,  if  not  earlier. 
Glacial  and  Champlain  phenomena  were  thus  cotemporaneous.  Nevertheless 
the  periods  stand  well  apart  in  the  great  epeirogenic  movement,  or  change 
of  level,  that  separates  them,  and  in  the  continuation  of  Champlain  con- 
ditions long  after  the  ice  had  disappeared. 

Review  of  modern  Glacial  phenomena.  — The  general  phenomena  and  laws  of  Glacial 
Geology  have  been  stated  on  pages  232-250,  and  illustrated  in  part  by  facts  from  an  existing 
continental  glacier  —  that  of  Greenland.  As  there  explained,  the  glacier  moves  over  hills 
and  ridges,  up  slopes  as  well  as  down,  the  pitch  of  its  upper  surface  determining  its  direc- 
tion and  rate  of  movement.  It  is  greatly  aided  in  excavating  work  by  subglacial  streams, 
that  are  far  more  effectual  workers  than  ice  ;  which  streams  in  Greenland,  according 
to  H.  Rink,  probably  branch  widely  over  the  country,  like  a  regular  river-system,  and 
have  at  times  great  volume.  It  gathers  stones,  gravel,  and  sand,  for  transportation,  as 
well  as  large  rock-masses.  It  abrades,  through  the  stones  at  bottom,  rocky  surfaces 
passed  over,  and  corrades  the  transported  material,  making  rock-flour,  sand,  gravel,  and 
smoothed  or  scratched  stones  out  of  the  debris  taken  aboard ;  and  it  may  convert  the 
finer  material  into  clay.  It  deposits  rock-flour  and  other  debris  from  subglacial  streams 


HISTORICAL   GEOLOGY.        :; 

before  and  after  escape  from  the  ice-sheet,  and  makes  clay-beds,  sand-beds,  moraine.s, 
•drumlins,  eskers. 

It  makes  glacier  dams,  producing  thereby  large  lake-basins,  by  piling  up  the  ice  in 
-narrow  gorges,  or  by  pressure  against  the  sides  of  valleys,  and  thus  crossing  and  so 
closing  open  valleys  ;  and  small  lakes,  liable  to  frequent  discharges  (page  238),  by  pressure 
of  the  ice  against  the  side  of  the  valley  ;  and,  in  times  of  melting  and  dissolution,  it  may 
build  ice-dams  in  narrows  along  river  channels  out  of  blocks  of  floating  ice  and  ac- 
companying glacier  debris  or  drift,  converting  rivers  into  lakes.  Further,  the  glacier, 
wherever  it  flows,  usually  leaves  its  tracks  in  scratched,  grooved,  or  planed  surfaces,  upon 
the  rocks  passed  over ;  in  scratched  stones  distributed  through  the  drift  material ;  in 
large  scattered  bowlders  that  are  traceable  to  a  source  in  a  direction  opposite  to  that 
of  the  movement ;  and  also  in  its  moraines  and  other  drift  accumulations.  In  the  use  of 
glacial  scratches  to  determine  the  direction  of  movement  of  the  ice-mass,  it  is  always 
to  be  noted  that  the  direction  is  quite  sure  to  be  diverted  from  that  of  the  general  ice- 
mass  by  valleys,  or  valley-like  depressions  in  the  surface  beneath  the  glacier  when  they 
-are  oblique  to  that  course,  even  if  the  depression  be  small ;  and  that  a  knoll  or  low  ledge 
of  rock  may  have  some  divergent  effect.  Only  scratches  on  high  land,  without  such 
sources  of  error,  are  to  be  trusted.  Moreover,  with  regard  to  traveled  material  or  drift, 
the  question  is  always  to  be  asked  whether  water  or  floating  ice  may  not  have  been  the 
transporting  agent. 

A  glacier  period  in  geological  history  was  first  recognized  in  1837  by  Louis  Agassiz, 
before  the  Helvetic  Society  of  Natural  History,  and  in  1840  announced  at  the  meeting  of 
the  British  Association.  Agassiz  visited  Scotland  to  verify  his  theory.  He  says  in  a 
letter  to  Professor  Jamieson  (1840):  "I  had  scarcely  arrived  in  Glasgow  when  I  found 
remote  traces  of  glaciers;  and  the  nearer  I  approached  the  high  mountain  chains,  the 
more  distinct  these  became,  until,  at  the  foot  of  Ben  Nevis  and  in  the  principal  valleys, 
I  discovered  the  most  distinct  moraines  and  polished  rocky  surfaces,  just  as  in  the  valleys 
of  the  Swiss  Alps."  On  Nov.  4,  1840,  he  brought  the  subject  before  the  Geological 
Society  of  London.  His  theory  of  the  drift  was  for  awhile  opposed  by  advocates  of  the 
Iceberg  theo'ry,  but  it  now  has  general  acceptance. 

The  earlier  systematic  observations  on  the  drift  in  North  America  were  made  between 
1832  and  1842  by  E.  Hitchcock,  W.  W.  Mather,  C.  Whittlesey,  James  Hall,  and  others. 
Mather  devotes  many  pages  to  the  subject  in  his  New  York  quarto  report  (1842),  and 
states  that  he  had  gathered  facts  personally  from  New  England  to  the  meridian  of  97°  W. , 
''traveling  over  100,000  miles."  His  descriptions  of  Long  Island  drift,  and  that  of  the 
Coteau  des  Prairies  and  of  many  regions  between,  though  he  was  not  then  a  glacialist,  are 
excellent ;  and  they  are  supplemented  with  results  from  other  sources,  and  a  long  table 
giving  the  courses  of  glacial  scratches  over  different  parts  of  the  country. 

Among  the  later  investigators,  over  the  Eastern  and  Central  States,  there  are  C.  H. 
Hitchcock,  whose  work  has  been  mainly  in  New  England,  and  has  been  published  in  the 
Geological  Reports  of  Vermont  and  New  Hampshire,  and  elsewhere  ;  T.  C.  Chamberlin, 
whose  papers  have  appeared  in  the  Reports  of  the  Wisconsin  Geological  Survey,  those  of 
the  U.  S.  Geological  Survey,  and  in  other  places;  Warren  Upham,  who,  after  work  in 
New  England,  has  served  as  one  of  the  geologists  in  the  survey  of  Minnesota,  and  tem- 
porarily also  in  the  Canadian  Survey,  and  in  each  has  extended  his  studies  to  the  Winni- 
peg region  in  British  America  ;  F.  Leverett,  R.  D.  Salisbury,  J.  S.  Newberry,  G.  K.  Gilbert, 
W.  J.  McGee,  J.  C.  Branner,  Carvill  Lewis,  G.  F.  Wright,  and  others.  The  author's  pub- 
lications on  American  Glacial  history  range  from  1856  to  1893,  and  those  giving  the  results 
of  special  investigations,  from  1870,  onward. 

For  the  Rocky  Mountains  and  the  Pacific  Slope  within  the  United  States,  the  most 
important  publications  are  those  of  J.  D.  Whitney,  Clarence  King,  I.  C.  Russell,  J.  S. 
.Newberry,  and  J.  LeConte  ;  and  for  British  America,  those  of  Dawson,  G.  M.  Dawson, 
R.  Bell,  R.  G.  McConnell,  J.  B.  Tyrrell,  and  R.  Chalmers. 


CENOZOIC  TIME — QUATERNARY.  943 

1.  GLACIAL  PERIOD. 
AMERICAN. 

Three  subdivisions  or  epochs,  of  the  Glacial  period,  are  recognized: 
'(1)  the  EARLY  GLACIAL  EPOCH,  or  that  of  the  Advance  of  the  Ice  and 
its  maximum  extension;  (2)  the  MIDDLE  GLACIAL  EPOCH,  or  that  of  the 
First  Ketreat  of  the  ice;  (3)  the  LATER  GLACIAL  EPOCH,  or  that  of  the 
Final  Retreat. 

1.   Epoch  of  the  Advance. 
General  Condition  of  the  Continent  during  the  Advance. 

Topographical  and  fluvial  conditions.  —  The  continent,  when  the  Ice  age 
began,  had  its  high  mountains  and  full-grown  rivers.  The  elevating  of  the 
-continental  surface  that  was  begun  in  the  Tertiary  had  covered  the  land 
with  running  waters,  and  the  new  and  vigorous  streams  made  erosion  their 
first  work.  The  older  streams,  also,  that  had  reached  a  level  of  no  work, 
received  new  energy  and  were  set  to  work  deepening  their  channels,  leaving 
the  old  flood  grounds  as  terraces  to  mark  progress.  The  time  was  especially 
favorable  for  pre-glacial  erosion.  In  addition  to  this  growth  of  rivers, 
forests  took  rapid  possession  of  the  continent,  and  faunas  and  floras  greatly 
widened  their  range. 

As  the  cold  and  precipitation  increased,  the  time  finally  came  when  the 
heat  of  summer  was  not  sufficient  to  melt  all  the  snows  of  the  colder  season, 
and  then  began  glacial  accumulation.  For  a  while  glaciers  were  confined  to 
the  higher  mountains ;  but  gradually  all  glacier  areas  became  united  in  one 
great  continental  ice-sheet,  Greenland-like,  with  local  glaciers  only  along 
some  of  the  deeper  terminal  valleys. 

While  thus  spreading  over  the  land,  there  were  oscillations  in  the  progress 
of  the  ice-sheet,  as  in  modern  glacier  regions,  determined  by  meteorological 
cycles,  —  the  11-year  cycle  dependent  on  the  cycle  of  the  sun's  spots,  and  a 
longer  cycle  of  35  to  50  years,  as  now  in  the  Alps.  And  besides,  there  were 
other  sources  of  meteorological  change,  causing  longer  halts  and  recessions 
in  the  ice-sheet,  for  which  no  explanation  can  yet  be  given. 

A  large  ice-sheet  gives  a  temperature  of  32°  F.  to  the  air  above  it,  and  this 
favors  its  perpetuity.  But  the  southern  margin,  at  the  time  of  maximum 
advance,  was  in  middle  temperate  latitudes  with  the  tropics  not  far  away ; 
and  warm  or  hot  winds,  therefore,  were  at  hand  to  produce  large  fluctuations 
in  the  extension  of  the  ice  with  the  changing  seasons. 

Causes  determining  places  of  the  flrst  ice  and  of  greatest  accumulation.  — 
Since  the  ice  would  have  accumulated  most  rapidly  where  abundant  pre- 
cipitation and  low  temperature  were  combined,  the  region  of  earliest  com- 
mencement and  maximum  accumulation  would  have  been  over  the  eastern 
portion  of  the  continent  toward  the  Atlantic.  Along  the  coast  region  of 


944  HISTORICAL   GEOLOGY. 

New  England  and  Canada  the  annual  rainfall  is  now  45  to  50  inches  a  year,, 
and  it  was  then  probably  still  greater,  perhaps  55  to  60  inches.  Farther 
north,  at  the  present  time,  the  precipitation  decreases  while  the  cold 
increases.  In  northern  Labrador  the  former  is  reduced  to  20  inches.  In 
Greenland,  where  ice  is  perpetual  except  within  30  to  60  miles  of  the  coast, 
the  mean  annual  precipitation  is  but  10  inches. 

The  mean  annual  precipitation  west  of  New  England  over  three  fourths 
of  the  state  of  New  York  is  now  38  to  42  inches.  But  in  the  Mississippi 
valley,  over  Wisconsin,  it  varies  from  32  to  38  inches ;  and  over  the  larger 
part  of  Minnesota,  from  20  to  32  inches,  while  farther  north  in  Manitoba  it 
is  mostly  between  20  and  10  inches.  Moreover,  in  the  Continental  Interior 
the  summer  isotherms  make  a  long  sweep  north,  that  of  the  July  mean  of 
70°  F.  extending  beyond  Lake  Winnipeg,  even  to  56°  N.,  which  is  10°  of 
latitude,  or  700  miles,  farther  north  than  the  position  of  the  same  isotherm 
over  New  England.  Consequently,  New  England  would  have  made  a  large 
accumulation  long  before  the  Mississippi  valley  in  the  same  latitudes  had 
any  permanent  ice.  And  after  the  ice  had  become  permanent,  it  might 
have  disappeared  over  the  Interior  while  on  the  eastern  border  it  was  still 
accumulating.  With  the  conditions  in  the  Continental  Interior  so  near  the 
critical  point,  the  ice-mass  there  would  have  responded  readily  to  changes  of 
temperature ;  a  meteorological  change  might  have  carried  off  the  ice  for  a 
breadth  of  scores  or  hundreds  of  miles,  which  would  have  made  no  impres- 
sion in  corresponding  latitudes  to  the  eastward. 

At  the  same  time,  in  latitudes  beyond  60°  N.,  the  precipitation  might  be 
too  small  for  great  accumulation  and  glacial  movement.  However  great  the 
cold  became,  the  icy  heights  to  windward  were  everywhere  robbing  the  air 
of  its  moisture,  and  so  leaving  little  for  the  regions  to  leeward. 

Southern  limit  of  the  ice.  —  Under  such  various  conditions  the  ice  became 
distributed  over  the  breadth  of  the  continent  from  the  Atlantic  Ocean  to 
the  Pacific. 

The  map  of  North  America,  Fig.  1548,  shows  the  southern  limit  of  the 
ice-sheet,  as  ascertained  from  the  traces  it  left  over  the  surface.  The  limit 
is  indicated  by  the  heavy  line  crossing  the  map  from  southeastern  Massa- 
chusetts over  southern  Illinois  and  northern  Montana  to  the  Pacific  coast. 
Its  most  eastern  observed  point  is  Nantucket ;  thence,  it  extends  along  the 
islands  south  of  New  England,  to  Perth  Amboy  in  New  Jersey.  Farther 
east  and  northeast  its  course  was  probably  over  George's  Shoal,  150  miles 
east  of  Cape  Cod,  where  the  minimum  depth  is  now  but  a  few  feet,  and  over 
the  shoal  region  off  Nova  Scotia  (by  Sable  Island)  and  Newfoundland. 
From  Perth  Amboy  it  crossed  New  Jersey  and  Pennsylvania  obliquely, 
entered  for  a  short  distance  western  New  York ;  then  bent  south  westward 
to  southern  Illinois.  Beyond  the  Mississippi  and  the  meridian  of  97°  W.  it 
made  a  bend  northward  to  47°  N.,  on  account  of  the  dry  and  warm  summer 
climate  of  the  Continental  Interior,  and  near  this  parallel  it  reached  the 
Pacific  coast.  But  in  the  Rocky  Mountain  or  Cordilleran  region,  it  covered 


40- 


90 


MAP  OF 

NOBTCH  AMERICA  *r 

ILLUSTRATING   THE    PHENOMENA 

OF  THE 

GLACIAL  AND  CHAMPLAIN  PERIODS. 

Limit  of  ice  sheet  • — • 

Moraines  -•« < 

Mean  direction  of  Glacial  scratches  \\\ 
^          Former  shore  line  of  lakes  


70 


CENOZOIC   TIME  —  QUATERNARY.  945 

the  higher  summits  at  intervals,  even  as  far  south  as  New  Mexico.  Again, 
there  were  isolated  glacier  regions  along  the  Cascade  Range  and  the  Sierra 
Nevada,  about  Rainier,  St.  Helens,  Hood,  Shasta,  Lyell,  and  other  summits ; 
and  in  the  Great  Basin,  on  Jeff  Davis  Peak,  the  East  Humboldt  Range, 
Shoshone  Range,  and  West  Humboldt  Range.  Shrunken  relics  of  the  old 
glaciers  still  linger  about  the  Wind  River  Mountains  in  Wyoming;  on 
Mount  Lyell  and  Mount  Dana  in  the  Sierra  Nevada ;  and  on  Shasta,  Rainier, 
and  other  summits  of  the  Pacific  coast  region. 

East  of  the  summit  range  of  the  Rocky  Mountains  in  British  America, 
the  limit  between  the  eastern  drift,  or  that  from  the  region  east  of  Lake 
Winnipeg,  and  the  western,  or  that  of  the  mountains  beyond,  has  the  posi- 
tion shown  by  the  dotted  line  on  the  map,  Fig.  1548,  the  height  being  3000 
to  3700  feet  above  sea  level. 

There  was  also  a  northern  limit  to  glaciation  in  northwestern  America, 
according  to  G.  M.  Dawson.  The  line  crossed  the  plateau  region  of  British 
Columbia,  between  60°  and  64°  N.,  and  consequently  Alaska  was  uncovered 
—  a  fact  confirmed  by  the  more  recent  observations  of  Dall  and  Russell. 
Greenland  had  probably  no  more  ice  than  now. 

The  details  on  the  map  (Fig.  1548)  with  reference  to  the  moraines  from  the  Mississippi 
to  New  Jersey  have  been  obtained  chiefly  from  published  and  unpublished  notes  of 
Chainberlin  and  Leverett ;  those  over  Iowa  and  Minnesota,  from  W.  Upham  ;  those  about 
the  Coteau  des  Prairies,  from  I.  E.  Todd ;  and  those  farther  north,  from  G.  M.  Dawson ; 
for  the  position  of  the  southern  ice-limit,  or  Moraine  line  A,  from  H.  C.  Lewis,  Report  Z  ; 
The  Terminal  Moraine  in  Pennsylvania,  1884',  from  G.  F.  Wright ;  for  the  line  westward 
to  the  Mississippi,  Lewis's  Report  Z,  and  also  Wright's  Ice  Age,  etc.  ;  for  the  positions 
of  the  glacial  lakes  of  Manitoba,  from  W.  Upham  ;  those  of  the  lakes  of  the  Great  Basin, 
from  G.  K.  Gilbert  and  I.  C.  Russell;  for  the  glacial  striae  over  New  England,  from 
C.  H.  Hitchcock  mainly  ;  and  those  of  other  regions  from  Chamberlin's  map,  lih  Ann.  Hep. 
U.  S.  G.  S.,  and  other  sources. 

Condition  outside  of  the  Ice-limit.  Forced  migration.  —  South  of  the  Ice- 
limit,  the  precipitation  was  probably  as  heavy  as  to  the  north  of  it.  But  it 
made  only  deep  snows  about  the  Appalachians  and  other  low  mountains, 
and  contributed  water  abundantly  to  rivers  and  lakes.  Over  a  narrow  belt 
near  the  front,  there  would  have  been  marshes  and  ponds  with  Arctic  vege- 
tation, and  cold-climate  Mammals,  which  had  been  driven  southward. 

Several  of  the  emigrant  plants  still  remain  and  thrive  on  the  summits  of 
the  mountains  of  both  eastern  and  western  North  America.  Thirty-seven 
species,  according  to  Asa  Gray,  occur  on  the  White  Mountains  of  New 
Hampshire,  and  part  of  them  also  on  the  Adirondacks  and  Green  Mountains. 
Out  of  27  species  observed  by  the  Jensen  expedition  on  a  Greenland  Nunatak 
in  1878,  the  White  Mountain  flora  includes,  according  to  Gray,  the  Grasses 
Luzula  hyperborea  and  Trisetum  subspicatum,  the  Sorrel,  Oxyria  digyna,  the 
Moss-like  Heath,  Cassiope  hypnoides,  and  the  Moss-like  Catchfly,  Silene 
acaulis.  Sedum  rhodiola,  a  subalpine  species,  occurs  on  cliffs  of  the  Dela- 
ware, below  Easton,  Pa. ;  Saxifraga  oppositifolia  Linn.,  on  Mount  Willoughby, 
DANA'S  MANUAL  —  60 


946  HISTORICAL    GEOLOGY. 

in  Vermont ;  Arenaria  Gronlandica,  on  the  White  Mountains,  the  Catskills, 
Shawangunk  Mountain,  and,  in  the  form  of  A.  glabra  Michx*,  on  the  Alle- 
ghanies  of  Carolina ;  Scirpus  ccespitosus  in  North  Carolina,  a  patch  remain- 
ing on  Roan  Mountain,  and  Nephroma  arcticum,  and  other  northern  Lichens, 
with  Lycopodium  selago  on  the  highest  Alleghanies. 

Even  freshwater  shells  of  the  Unio  family  were  among  the  immigrants, 
as  C.  T.  Stimson  has  found  by  a  study  of  fossil  shells  from  near  Toronto. 
Scudder  has  shown  that  in  North  America  the  fossil  Coleopterous  Insects  of 
deposits  laid  down  in  the  Glacial  period  are  very  nearly  all  of  extinct  species, 
while  those  from  peat  beds  of  later  origin  are,  with  a  rare  exception,  existing 
species. 

The  bones  of  the  Reindeer  have  occasionally  been  found  in  the  valley 
drift.  Two  bones,  referred  by  Marsh  to  the  Arctic  Reindeer,  Rangifer 
tarandus,  were  found  in  the  lower  clay-beds  of  the  Quinnipiac  River,  three 
miles  north  of  New  Haven,  and  others  have  been  reported  from  near  Vincen- 
town,  N. J.  Other  remains,  but  possibly  of  the  R.  caribou,  have  been  found 
near  Sing  Sing,  N.Y.,  in  Kentucky  at  Big-bone  Lick,  and  on  Racket  River 
in  northern  New  York. 

The  region  farther  south  abounded,  no  doubt,  in  the  beasts,  birds,  and 
other  species  of  a  temperate  climate.  With  so  long  a  glacial  front  in  lati- 
tudes of  40°  to  35°,  at  the  time  of  greatest  extension,  the  extreme  cold 
would  have  swept  at  times  over  the  south,  and  have  probably  excluded 
from  the  region  north  of  Florida  tropical  and  subtropical  species,  excepting 
migrating  kinds. 

Elevation  of  the  Continent. 

The  evidence  that  the  continent,  especially  over  its  northern  portions 
and  along  the  mountain  borders,  continued  its  rise  above  the  sea  level  after 
the  Tertiary  period  is  based  largely  on  the  facts  relating  to  river  channels, 
fiords,  and  Arctic  migrations  between  Europe  or  Asia  and  America. 

Evidence  from  river  channels  and  fiords.  —  Near  and  beneath  the 
southern  margin  of  the  ice,  over  the  interior  of  the  continent,  many  river 
channels,  as  proved  by  borings,  have  a  depth  of  100  to  400  feet  below  their 
present  bed.  These  deep  gorges  are  filled  with  drift,  thus  making  it  certain 
that  the  excavation  was  completed  in  the  Glacial  period.  Newberry  states 
that  all  the  river  valleys  of  Ohio  are  examples.  The  Cuyahoga,  which  is 
one  of  them,  has,  where  it  enters  Lake  Erie,  its  bottom  200  feet  below  the 
present  bed,  and  this  continues  for  20  miles  up  the  stream.  The  valleys  of 
northern  Pennsylvania  are  other  examples,  and  according  to  Carll  and 
White  the  depth  of  the  drift-filling  is,  in  some  cases,  300  to  400  feet.  At 
the  west  end  of  Lake  Ontario,  the  Dundas  gorge  has  been  proved  by  borings 
to  descend  227  feet  below  the  sea  level,  or  nearly  half  as  far  as  the  deepest 
part  of  Lake  Ontario,  the  material  penetrated  by  the  boring  being  drift 
(J.  W.  Spencer).  It  is  inferred  that  the  lake  was  above  the  sea  level  in  the 
period,  and  that  a  river  flowed  along  its  bottom,  either  eastward  or  westward, 


CENOZOIC    TIME  —  QUATERNARY.  947 

and  produced  the  excavation.  The  depth  of  Lake  Ontario  is  738  feet,  492 
•of  which  are  below  tide  level;  and  hence  the  minimum  elevation  that 
would  give  the  same  slope  to  the  water  as  now  was  738  feet.  As  shown  on 
the  map  on  page  201,  this  Ontario  River  (or  the  line  of  greatest  depth)  was 
near  the  south  shore ;  and  the  depression  had  a  high  declivity  on  that  side 
which  was  very  steep  for  the  first  500  feet.  Similar  conclusions  may  be 
drawn  from  all  the  Great  Lakes ;  for  they  are  generally  believed  to  have 
been  excavated  by  running  waters  during  the  Glacial  period.  The  map  on 
the  page  referred  to  has  marked  upon  it  the  outlines  of  the  drainage  areas  of 
the  several  lakes,  the  deep-water  line,  and  the  position  of  the  point  of  maxi- 
mum depth  ;  and  Schermerhorn  remarks  that  the  deep-water  line  of  each  is 
near  the  center  of  the  area  of  drainage.  The  Lake  Superior  basin  descends 
407  feet  below  sea  level;  the  Michigan,  289  feet;  the  Huron,  121  feet. 
For  fluvial  excavation,  the  elevation  must  have  been  not  only  that  which 
would  raise  the  basins  above  sea  level,  but  to  a  height  above  the  surrounding 
land  that  would  enable  even  the  bottom  waters  to  flow  out  of  the  drainage 
basins  ;  and  to  pass,  not  the  existing  drainage  barriers,  but  the  barriers  of  the 
Glacial  period,  when  the  land  in  the  vicinity  was  far  above  its  present  level. 

A  change  of  level  is  also  proved  by  the  reversed  flow  of  some  streams. 
'Carll  and  others  have  shown  that  the  Pennsylvania  rivers,  the  Alleghany  and 
Beaver,  then  flowed  northward  into  Lake  Erie,  proving  that  the  land  dipped 
toward  the  Erie  basin.  In  the  Beaver  River  channel  in  western  Penn- 
sylvania, now  a  tributary  of  the  Ohio,  the  filling  of  drift,  according  to  Foshay 
and  Mice  (1890),  is  only  60  feet  deep  at  its  mouth ;  but  20  miles  above,  it  is 
200  feet,  according  thus  with  the  view  that  its  drainage,  as  shown  by  Carll 
for  the  Alleghany,  had  been  reversed.  The  Tionesta  and  Conewango  basins, 
according  to  Carll,  participated  in  reversed  Erie-ward  pitch.  Facts  on  this 
subject  of  reversed  drainage  are  presented  by  Chamberlin  in  a  paper  of  1894, 
along  with  illustrating  maps.  Moreover,  Gilbert  pointed  out  in  1871,  that  the 
Maumee  River,  now  emptying  into  the  west  end  of  Lake  Erie,  then  flowed 
westward,  and  joined  the  Wabash,  and  thus  made  the  lake  a  tributary  to  the 
Ohio.  He  found  the  evidence  both  in  westward  glacial  scratches  and 
moraines,  and  in  lake  terraces.  It  is  possible  that  a  Huron  River  made 
another  Ohio  tributary. 

Again,  Lake  Winnipeg,  as  pointed  out  by  G.  K.  Warren  (Rep.  U.  S. 
Engineer  Dept,  1867,  1874,  and  Am.  Jour.  Sc.,  xvi:,  417,  1878),  which  now 
discharges  into  Hudson  Bay  by  the  short  Nelson  River,  formerly  discharged 
into  the  Mississippi,  and,  with  the  Saskatchewan  River,  was  its  northern 
head  waters.  At  the  present  time,  the  level  of  the  lake  is  about  260  feet ; 
too  low  for  a  southward  flow.  The  divide  is  in  Minnesota  between  Big  Stone 
Lake,  the  head  waters  of  Minnesota  River,  and  Lake  Traverse,  the  head 
waters  of  Red  River  of  the  North,  a  Winnipeg  tributary.  These  two  little 
lakes  are  but  a  few  miles  apart  and  differ  but  eight  feet  in  level.  The  valley 
of  Red  River  and  that  of  the  Minnesota  were  found  by  Warren  to  be  con- 
tinuous, and  to  be  a  great  valley  across  the  divides,  125  to  150  feet  deep,  and 


948  HISTORICAL   GEOLOGY. 

a  mile  and  a  half  wide,  enlarging  southward  to  its  junction  with  the  Missis- 
sippi valley;  and,  in  contrast,  the  valley  of  the  Mississippi  north  of  this 
junction  is  small.  He  thus  obtained  positive  evidence  that  the  valley  and 
river  from  Winnipeg  southward  was  not  long  since  one,  and  that  the  conti- 
nental level  was  then  such  as  would  give  the  southward  flow  to  the  waters. 
To  reproduce  now  this  slope  would  require  a  rise  of  the  Winnipeg  region 
(or  a  sinking  of  the  divide)  amounting  to  about  260  feet ;  and  to  give  the 
waters  also  a  pitch  of  half  a  foot  a  mile,  an  additional  165  feet.  The  former 
existence  of  this  greater  Mississippi  is  also  shown  by  the  fact  that  fresh- 
water shells  of  the  Winnipeg  region  also  live  in  the  Mississippi. 

Warren  also  suggested  that  Lake  Michigan  at  the  same  time,  owing 
to  the  same  northern  uplift,  discharged  by  the  Illinois  Eiver  into  the 
Mississippi — its  broad  and  deep  valley  widening  in  the  vicinity  of  the  lake 
in  accordance  with  this  direction  of  flow. 

The  changes  about  all  the  Great  Lakes  were  such  as  tended  to  give  them 
probably  independent  outlets.  The  channels  that  now  unite  them  are  all 
shallow,  generally  not  exceeding  50  feet. 

Further  proof  of  high-latitude  elevation  in  the  Glacial  period  is  afforded 
by  the  river-valleys  of  the  coast  region  now  filled  with  water,  that  is  the 
fiords,  and  the  multitudes  of  islands,  and  many  channels  among  islands,  along 
fiord  coasts.  The  fiords  of  Maine,  Labrador,  Newfoundland,  Greenland, 
British.  Columbia  and  Alaska,  and  those  of  Scandinavia,  western  South 
America  south  of  41°,  of  Tasmania  and  South  Australia,  are  such  valleys,  and 
they  all  are  confined  to  Glacial  latitudes.  None  occur  on  southern  Africa, 
which  reaches  only  to  34°  22'  S.  They  were  made  when  the  land  stood  high 
enough  for  the  denudation  of  the  rocky  coast  region ;  and  in  view  of  the 
great  lift  the  continent  and  other  continents  were  having  in  the  Later  Ter- 
tiary time  and  during  the  opening  Quaternary,  it  is  a  reasonable  supposition, 
as  the  author  pointed  out  in  1856,  that  the  work  of  excavation  should  have 
gone  forward  during  the  Glacial  period.  It  cannot  be  affirmed  that  the  work 
of  denudation  was  not  begun  during  emergencies  long  before  ;  but  if  so,  this 
period  of  so  widely  extended  elevation,  probably  the  greatest  in  the  world's 
history,  must  have  finished  the  work. 

Some  of  the  fiords  of  the  Atlantic  coast  between  southern  Maine  and 
Hudson  Bay  have  been  found  by  soundings,  as  stated  by  Spencer,  to  have 
depths  of  2000  to  3670  feet  below  the  sea  level ;  and  the  St.  Lawrence  chan- 
nel below  the  Saguenay  has  afforded  soundings  of  1104  and  1878  feet.  The 
Saguenay  gorge  descends  300  to  840  feet  below  the  sea  level  and  rises  1500 
feet  above  it.  They  compare  well  with  the  fiords  of  the  Scandinavian  coast, 
several  of  which  are  above  2000  feet  in  depth,  and  one,  the  Sogne  Fiord, 
4020  feet. 

The  fiords  of  a  coast  differ  widely  in  breadth  and  depth;  and  the  deepest 
and  largest  were  probably  those  channels  that  had  been  excavated  to  the  sea 
level,  during  the  time  of  emergence,  while  others  are  the  shallower  gorges 
of  the  denuded  region.  They  have  generally  at  present  a  bottom  of  drift 


CENOZOIC   TIME  —  QUATERNARY.  949 

or  other  detritus,  so  that  the  actual  depth  of  excavation  may  much  exceed 
that  obtained  by  soundings. 

From  such  facts  it  is  reasonable  to  estimate  the  elevation  of  portions  of 
British  North  America  along  the  Canadian  watershed,  or  the  great  Ice- 
plateau,  to  have  been  at  least  3000  feet  above  the  present  level.  This 
subject  has  been  recently  well  discussed  by  Upham,  with  this  estimate  as 
his  conclusion.  The  author,  in  1871,  suggested  5000  feet,  and  this  may  not 
be  too  high  for  some  portions  of  the  Canadian  region  of  highest  ice.  With 
3000  feet  for  the  Canada  watershed  south  of  Hudson  Bay,  this  bay  must 
have  been  largely  dry  land.  Along  the  coast  of  Maine  the  elevation  indi- 
cated is  less  than  a  thousand  feet. 


South  of  Maine,  on  the  New  England  coast,  other  fiord-like  indentations  of  the  coast 
exist  in  Narragansett  Bay,  R.I.,  and  the  gorge  of  the  Thames,  from  New  London  to 
Norwich,  Conn.  Besides  these,  there  are  pot-holes  in  the  gneiss  of  islands  off  the 
Connecticut  coast ;  and  those  of  the  Thimble  Islands,  in  the  bay  of  Stony  Creek,  show  that 
this  bay  was  formerly  crossed  and  probably  excavated  by  a  freshwater  stream.  The  great 
depth  of  the  bays  on  the  north  side  of  Long  Island,  50  to  65  feet  notwithstanding  the 
later  drift  deposits  over  the  region,  is  further  proof  of  elevation.  The  amount  for  southern 
New  England  and  Long  Island  could  not  have  been  less  than  150  feet  (D.,  1870).  With 
this  elevation,  Long  Island  Sound  in  the  Ice  period  would  have  been,  instead  of  an  arm  of 
the  sea,  the  channel  of  a  river  tributary  to  the  larger  Connecticut  River;  and  Long 
Island  with  New  York  on  the  west  side  and  the  south  coast  of  New  England  on  the  east 
would  have  been  continuous  dry  land.  (See  map,  page  18.)  The  soundings  of  the  Sound 
and  of  the  waters  south  of  Long  Island  are  shown  on  this  map,  and  also  more  fully  in  Am. 
Jour.  $£.,  xl.,  1890,  with  explanations  in  the  same  volume. 

If  the  fiords  of  the  coast  are  proof  of  elevation,  the  absence  of  them  farther  south 
should  be  probable  evidence  of  little  elevation  or  none.  The  submarine  Hudson  River 
channel  (map,  page  18)  indicates  a  former  emerged  condition  of  the  sea  bottom,  requiring 
an  elevation  of  the  region  and  the  adjoining  coast  of  2800',  judging  from  the  deepest  part ; 
and  it  has  been  inferred  by  Lindenkohl  and  Upham  that  this  elevation  took  place  in  the 
Glacial  period.  But  the  facts  from  the  New  England  coast  indicate  only  small  elevations. 
Moreover,  the  origin  of  the  submerged  Hudson  River  channel  appears  to  have  been  of 
much  earlier  date,  as  has  been  explained  on  page  744. 

J.  W.  Spencer  has  inferred  from  the  Coast  Survey  maps  that  there  are  submarine 
river  channels  off  the  mouths  of  several  of  the  rivers  of  the  coast  south  of  Cape  Hatteras, 
and  in  the  Gulf  of  Mexico,  the  Mississippi  included.  But  no  satisfactory  evidence  of  such 
channels  exists  on  these  charts,  in  the  opinion  of  officers  of  the  Coast  Survey. 


G.  M.  Dawson  states,  with  reference  to  the  fiord  region  of  western 
America,  that  the  land  in  the  Pliocene  stood  relatively  to  the  Pacific  about 
900  feet  higher  than  now  ;  and  he  concludes  that  the  fiords  were  shaped  and 
enlarged  locally  during  the  following  Glacial  period,  when  the  amount  of 
elevation  was  still  further  increased.  The  submerged  river  channels  of  the 
Pacific  coast  of  North  America,  on  the  coast  of  California,  as  described  by 
G.  Davidson  (1887),  descending  to  depths  of  2400,  3120,  and  2700  feet, 
indicate  a  higher  level  of  the  region  of  2500  to  3000  feet,  and  probably  during 
the  Glacial  period. 


950 


HISTORICAL   GEOLOGY, 


Evidence  from  Mammalian  migration  between  North  America  and  Europe 
or  Asia.  —  Another  argument  for  the  elevation  of  the  land  of  the  higher 
latitudes,  and  particularly  the  polar,  has  been  drawn  from  the  fact  that  the 
migration  of  Plants  and  Mammals  took  place  between  the  two  continents  in 

1549. 


Bathymetric  map  of  the  Arctic  seas,  reduced  from  the  chart  of  the  U.  S.  Topographic  Department. 

the  Quaternary.  The  migrating  species  include  the  Keindeer,  Moose,  Elk, 
Polar  Bear,  Grizzly  Bear  (the  Brown  Bear,  Ursus  Arctos  of  Europe,  being 
regarded  as  identical  with  the  Grizzly),  Beaver,  and  probably  other  Mammals. 
There  were  also  even  migrating  Unios,  one  species,  Margaritana  margaritifera, 


CENOZOIC    TIME  —  QUATERNARY.  951 

occurring  in  northern  Europe  and  Asia,  and  also  in  North.  America  from 
British  Columbia  to  California,  and  on  the  east  from  eastern  Canada  to 
Pennsylvania.  These  facts  prove  land  communication.  Dry  land  at  Bering 
Straits  would  have  sufficed,  and  required  an  elevation  of  but  200  feet.  But 
there  was  probably  connection  also  across  from  Europe  to  Arctic  America. 
The  connection  was  prolonged  for  the  polar  part  into  the  Champlain  period. 

The  accompanying  bathymetric  map  will  aid  in  appreciating  the  effects 
of  a  change  of  land  in  the  Arctic  regions.1  An  elevation  now  of  but  1000 
feet  would  add  certainly  700  to  1000  miles  to  the  width  in  a  northward  direc- 
tion of  Europe  and  Asia,  putting  Franz  Joseph  Land  along  the  northern 
margin,  and,  perhaps,  much  of  the  unsounded  region  farther  north.  Only 
about  650  miles  intervene  between  northern  Spitsbergen  and  Greenland. 
The  map  shows  further  that  an  elevation  of  3000  feet  would  make  a  dry 
land  passage  from  Norway  by  Britain  to  Greenland,  drying  up  the  German 
Sea,  and  probably  nearly  the  whole  of  the  Arctic  Ocean.  The  waters  north 
of  Melville  and  Bathurst  lands  may  be  as  shallow  as  those  north  of  Lapland. 

Apparent  upward  change  due  to  change  in  tvater  level.  —  Part  of  the  appar- 
ent upward  change  of  level  may  have  been  only  a  downward  change  in  the 
water  level  of  the  ocean.  Agassiz,  holding  that  ice  covered  nearly  the  whole 
continental  area  of  the  globe,  argued  that  the  abstracting  of  water  from  the 
ocean  to  make  ice  would  have  occasioned  a  large  continental  emergence. 
But  the  proportion  that  was  actually  covered  was  so  small  relatively  to  the 
whole  surface  of  the  globe  that  the  consequent  emergence  could  not  have 
exceeded  60  feet.  South  America  has  but  a  narrow  strip  in  glacial  latitudes, 
and  the  ice  areas  of  Australia  and  New  Zealand  were  very  small. 

Another  cause  affecting  the  water  level  was  the  attraction  of  the  mass  of 
the  high  ice-plateau.  It  acted  on  the  ocean's  waters  like  that  of  any  other 
elevated  land-mass,  by  drawing  the  water  up  over  the  land,  and  thus  occa- 
sional actual  submergence.  The  effect  was,  therefore,  opposite  to  that  from 
the  loss  of  water  for  making  ice. 

Height,  Thickness,  and  Flow  of  the  Ice. 

Evidence  from  glacial  scratches  and  transported  bowlders.  —  On  the  map, 
Fig.  1548,  the  mean  directions  of  glacial  scratches  are  marked  by  arrows, 
and  these  directions  are  taken  in  all  cases,  as  far  as  could  be  ascertained, 
from  the  results  of  observations  over  the  higher  land  of  a  region,  away  from 
the  influence  of  valleys  or  depressions. 

Positive  facts  as  to  the  height  of  the  ice  in  particular  localities  are  few. 
Scratches  observed  by  E.  Hitchcock  on  Mount  Washington,  in  1841,  put  the 
limit,  in  that  part  of  New  England,  above  5500  feet ;  and  the  more  recent 
discovery  by  C.  H.  Hitchcock  (1875)  of  transported  bowlders,  some  of  them 
90  pounds  in  weight,  near  the  summit  of  the  mountain  (6293  feet  above  the 
sea  level),  proves  that  the  mountain  was  completely  covered,  and  that  the 

1  The  depths,  on  the  map,  are  given  in  100  fathoms,  5  signifying  500  fathoms  or  3000  feet, 
and  .5,  50  fathoms.  The  arrows  show  courses  of  marine  currents. 


952  HISTORICAL   GEOLOGY. 

height  of  the  ice  was  not  less  than  6500  feet.  Mount  Mansfield,  the  highest 
summit  of  the  Green  Mountains,  Vt.,  4389  feet  high,  was  wholly  under 
ice,  as  proved  by  transported  bowlders.  Mount  Katahdin,  in  Maine,  has 
bowlders  to  a  height  of  4700  feet.  The  Catskills  have  marks  of  glaciation  to 
a  height  of  3200  feet  (Smock,  1873),  and  Elk  Mountain,  in  northeastern 
Pennsylvania,  to  a  height  of  2700  feet  (Branner).  It  is  probable  that  Mount 
Katahdin  and  some  peaks  in  the  Catskills  were  "  Nunataks." 

Evidence  from  the  pitch  required  for  movement.  —  From  the  probable  pitch 
of  the  upper  surface  of  the  ice-sheet  required  for  movement,  estimates  may 
be  obtained  of  the  height  of  the  ice  in  other  regions. 

In  Greenland,  flow  takes  place  when  the  slope  of  the  surface  of  the  ice  is 
but  0°  26',  or  40  feet  to  the  mile  =  1 : 132 ;  and  Helland  obtained  for  the 
maximum  rate  of  flow,  where  the  slope  of  surface  was  less  than  half  a 
degree,  20  meters  per  day.  If  the  rate  of  slope  between  the  summit  over 
the  White  Mountains  and  the  southeast  side  of  Martha's  Vineyard  (which 
was  the  course  of  movement)  was  only  30  feet  per  mile,  then  the  height  of 
the  ice-surface  over  these  mountains  was  about  6500  feet;  and  it  would  have 
been  a  third  larger,  if  40  feet  per  mile.  A  like  calculation  for  the  Adiron- 
dacks  gives  a  height  of  about  7000  feet.  The  height  of  the  ice  on  the  Cats- 
kill  Mountains,  mentioned  above,  3200  feet,  corresponds  with  the  latter 
estimate ;  for  the  distance  of  these  mountains  from  the  southern  limit  of  the 
ice,  near  Perth  Amboy,  N.J.,  is  nearly  one  half  as  great  as  that  of  the 
Adirondack  summits.  Moreover,  drifted  stones  of  hypersthene  rock  from 
the  Adirondacks  occur  upon  them,  as  stated  by  Mather. 

The  ice  of  the  Adirondack  region  flowed  south-southeastward,  over  eastern 
Connecticut,  into  what  might  be  called  the  realm  of  the  White  Mountains, 
and  it  did  this  notwithstanding  the  obstructing  Green  Mountain  range 
on  the  route;  and  this  is  evidence  that  the  Adirondack  part  of  the  ice- 
plateau  was  the  higher.  By  the  same  kind  of  evidence,  the  height  of  the 
watershed  between  the  St.  Lawrence  and  Hudson  Bay,  toward  which 
the  scratches  over  northern  and  northwestern  New  England  point,  is  found 
to  be  13,000  feet.  But  this  part  of  the  Laurentide  ice-plateau  may  have 
been  nearly  level  for  a  long  distance  south  of  its  summit,  so  that  the  height 
may  not  have  exceeded  10,000  feet.  Again,  Mount  Katahdin  is  60  miles  from 
the  summit  of  the  mountain  range  that  stands  between  Maine  and  the  St. 
Lawrence  River ;  and  hence  the  height  of  the  ice  over  this  range  was  about 
6500  feet,  if  4700  feet  at  Katahdin. 

Across  Wisconsin  the  distance  from  the  south  shore  of  Lake  Superior  to 
the  southern  ice-limit  is  not  less  than  500  miles,  and  a  slope  of  but  20 
feet  a  mile  would  give  a  height  at  the  lake  of  10,000  feet.  Part  of  the 
10,000  feet  was  made  by  the  greater  height  of  the  land  in  the  Lake  Superior 
region.  The  difference  in  elevation  now  is  about  1000  feet.  It  was  probably 
greater  in  the  Glacial  period,  through  the  increased  elevation  of  the  Lake 
Superior  region.  As  reported  by  C.  A.  White,  a  mass  of  native  copper,  of 
30  pounds  weight,  was  taken  from  the  drift  of  southern  Iowa,  Lucas  County, 


CENOZOIC    TIME QUATERNARY.  953 

and  other  smaller  pieces  from  other  parts  of  the  state,  and  also  from  the 
southern  part  of  Illinois.  It  came  from  the  Keweenaw  Copper  region, 
in  northern  Michigan,  south  of  Lake  Superior,  for  this  is  the  only  possible 
source.  The  distance  is  about  450  miles.  A  slope  of  20  feet  a  mile,  noting 
that  the  locality  in  Lucas  County  has  a  height  of  1000  feet,  would  give,  for  the 
height  of  the  ice-surface  in  the  Keweenaw  region,  10,000  feet.  The  present 
height  of  the  land  in  this  region  is  about  1500  feet ;  it  was  possibly  then 
3500  feet.  It  may  be  thought  that  detached  ice,  floating  down  the  Mississippi, 
might  have  transported  the  copper.  But  the  Lucas  County  locality  is  about 
120  miles  west  of  this  river,  and  500  feet  higher  than  the  land  at  Burlington, 
Iowa,  a  Mississippi  town. 

The  distribution  of  copper  in  the  drift  has  been  attributed  to  the  Indians. 
But  in  all  probability  they  would  have  gathered  it  from  the  drift,  and  thus 
•  diminished  the  amount  rather  than  increased  it. 

The  distance  of  travel  appears  to  have  been  still  greater  in  British 
America.  Along  a  line  from  the  Laurentide  ice-plateau  in  Canada,  across 
the  region  of  Lake  Winnipeg,  to  the  western  limit  of  the  drift,  even  a 
slope  of  12  feet  a  mile  would  make  the  height  of  the  Laurentide  ice-surface 
-over  8,000  feet.  The  drift  at  this  limit  contains  Archaean  bowlders  of  varying 
.size  up  to  a  length  of  40  feet,  which  proves  its  eastern  origin.  The  rocks  on 
the  west  side  of  Lake  Winnipeg  are  Archaean. 

With  the  slope  at  a  minimum,  the  rate  of  transportation  per  century 
would  be  at  a  minimum,  and  the  time  for  corrasion  and  decomposition, 
or  the  wearing  out  of  stones,  at  a  maximum;  so  that  the  material  for  the 
terminal  moraine,  under  such  circumstances,  should  be  at  a  minimum. 

The  thickness  of  the  ice  in  any  place  equaled  the  total  height  less  the 
elevation  of  the  land  beneath;  as  the  latter  is  an  unknown  quantity,  the 
actual  thickness  is  seldom  obtainable.  A  thickness  of  ice  of  4000  to  5000 
feet  probably  existed  along  the  Canada  watershed,  in  northern  New  England 
and  New  York,  and  west  of  New  York,  in  the  region  of  the  more  northern 
of  the  Great  Lakes ;  and  a  thickness  of  1000  to  3000  feet  was  common  over 
the  region  to  the  southward. 

One  large  area  of  snows  and  thin  ice  —  not  thick  enough  to  participate 
in  the  glacier  movement  —  existed  in  the  midst  of  the  moving  glaciers  of 
Wisconsin,  Iowa,  and  Minnesota.  It  is  now  driftless,  and  has  an  area  of 
12,000  square  miles  (map,  Fig.  1548).  J.  G.  Percival,  in  his  survey  of  Wis- 
consin, first  recognized  its  driftless  character,  and  J.  D.  Whitney,  in  1862, 
described  and  mapped  it.  It  is  now  an  area  of  minimum  winter  precipi- 
tation. The  ice  flowed  either  side  of  it,  passing  on  the  west  side  over  the 
•east  border  of  Iowa. 

Courses  of  glacial  scratches  in  the  White  Mountain  region,  New  Hampshire,  according 
to  C.  H.  Hitchcock :  Near  Lake  of  the  Clouds,  5000'  to  5200'  above  the  sea,  S.  34°-54°  E.; 
•on  the  N.  side,  near  top  of  Mount  Clinton,  4430',  17  m.  W.  of  Mount  Washington,  S.  50°- 
54°  E.  ;  and  on  S.  peak  of  Mount  Clinton,  4320',  S.  54°  E.  ;  between  Mount  Pleasant  and 
Mount  Franklin,  4400',  S.  30°  E.  ;  between  Mount  Pleasant  and  Mount  Clinton,  4050', 


954  HISTORICAL    GEOLOGY. 

S.  30°  E.  ;  S.  end  of  Mount  Webster,  S.  37°  E. ;  top  of  Mount  Webster,  4000',  S.  30°  E.; 
top  of  Moosilauke,  4811',  S.  22°  E.  Further,  on  Mount  Abraham,  in  Maine,  the  direction 
found  is  S.  59°  E. 

From  the  White  Mountains  to  the  coast  of  Maine,  along  by  Portland  and  the  mouth 
of  the  Kennebec,  the  distance  is  but  70  miles ;  and  hence,  supposing  the  pitch  of  the 
surface  the  same  as  to  Nantucket,  the  foot  of  the  glacier  in  that  direction,  as  remarked 
long  since  by  Agassiz,  was  over  the  shoals  off  the  coast  of  Maine,  south  of  Nova  Scotia, 
then  probably  an  emerged  area,  and  the  depth  of  ice  over  this  part  of  Maine  was  at  the 
least  4000'. 

The  direction  of  the  scratches  (see  map)  over  western  New  England  is  testimony  as 
to  the  Adirondack  source  of  the  ice.  The  following  are  observed  facts :  — 

Over  high  western  Connecticut,  1000'  to  1200'  above  the  sea,  in  Warren  and  Litchfield, 
S.  29°  E.  (D.);  in  Newtown,  S.  32°  E.  (D.)  ;  in  Sharon,  S.  33°-36°  E.  (D.);  in  Cornwall, 
S.  33°-36°  E.  (D.);  near  Norfolk,  S.  20°-25°  E.  (Mather);  on  Mount  Tom,  near  Litchfield, 
S.  17°-22°  E.  (Hitchcock)  ;  in  Goshen,  S.  23°  and  S.  28°  E.  (H.  Norton)  ;  on  Kent  Moun- 
tain, S.  19°  E.  ;  and  S.  of  Kent,  S.  38°  E.  (D.);  bowlders,  from  Canaan,  of  limestone  con- 
taining canaanite,  found  5  m.  W.  of  New  Haven,  S.  16°  E.  (D.). 

In  western  Massachusetts,  on  Mount  Washington,  in  its  southwest  corner,  on  the 
top  of  its  summit  peak  Mount  Everett,  2624' high,  S.  18°  E.  (Hitchcock),  S.  27°  E.  (D.)  ; 
on  top  of  the  ridge  Tom  Ball,  nearly  N.  of  Mount  Washington,  S.  43°  E. ;  on  the  Taconic 
Range,  W.  of  Richmond,  S.  53°-S.  70°  E. ;  on  top  of  Lenox  Mountain,  between  Stockbridge 
and  Richmond,  S.  41°-45°E.  (Benton);  E.  slope  of  Taconic  Range,  near  Pittsfield, 
S.  50°  E.  (D.);  on  the  mountain  between  Otis  and  Becket,  about  SE.  (Hitchcock). 

The  bowlder  train  (page  959)  over  Richmond  and  Lenox  has  the  course  S.  45°  E.  west 
of  Richmond,  and  S.  35°  E.  from  Richmond  through  Lenox. 

Over  the  higher  part  of  Vermont  (from  E.  and  C.  H.  Hitchcock's  Vermont  Hep.), 
mostly  S.  30°  E.-S.  55°  E.  the  greatest  to  the  northward ;  in  the  southern  portion  of  Ver- 
mont, in  Windham,  S.  28°  E.  ;  in  Wilmington,  S.  29°-39°  E.  ;  in  central  Vermont,  West 
Hancock,  S.  50°  E.,  Ripton,  S.  60°  E.  ;  in  northern  Vermont,  on  Camel's  Hump,  4077' 
above  the  sea,  S.  55°  E.,  on  Mount  Mansfield,  4389',  S.  55°  E.  ;  on  Jay's  Peak,  north  of 
the  last,  S.  50°  E. 

In  higher  parts  of  eastern  New  York,  in  Dutchess  County,  mostly  S.  15°-30°E. 
(Mather)  ;  near  Arthursville^  S.24°E.  (D.)  ;  in  Putnam  County,  near  Patterson,  S.  17°- 
22°  E.  (Mather)  ;  in  Columbia  County,  north  of  Dutchess,  S.  18°-30°E.,  and  on  moun- 
tain top  east  of  Shaker  village,  S.  45°  E.  ;  beginning  of  Richmond  bowlder  train  on  the 
borders  of  Lebanon  and  Canaan,  S.  55°-45°E.  (Benton). 

In  northern  Pennsylvania,  J.  C.  Branner  obtained  for  striae  on  Pocono  Mountain,  west 
of  Carbondale,  a  mean  course  of  about  S.  20°  W.-S.  30°  W. ;  and  on  the  summit  of  Bald 
Mountain  west  of  Scranton,  S.  10°  W.-S.  33°  W. 

The  facts  prove  that  from  all  western  New  England  the  flow  was  from  the  northwest- 
ward, across  the  Taconic  Range  and  the  Green  Mountains,  and  in  a  direction  from  the 
Adirondack  region,  or  the  more  elevated  Lauren  tide  region  beyond  it. 

The  distance  from  the  Adirondack  part  of  the  plateau  to  the  southwest  margin  of  the 
lobe  in  western  New  York  is  about  200  miles,  or  150  if  the  Adirondack  plateau  extends 
50  miles  west  of  Mount  Marcy.  It  is  about  250  miles  to  the  ice-lirnit  south  of  New  York, 
and  nearly  the  same  to  southern  Long  Island  in  the  line  over  New  Haven  ;  and  about  220 
miles  from  the  White  Mountain  center  to  the  southeast  side  of  Nantucket.  It  is  to  be 
noted,  however,  that  the  position  of  the  margin  in  western  New  York  was  1500'  above 
the  sea  level. 

A  bluff  facing  the  water  of  Lake  Cayuga,  about  a  mile  north  of  Ithaca,  according  to 
H.  S.Williams,  in  a  region  where  scratches,  flutings,  and  planings  of  the  rocks  are  exhibited 
on  a  grand  scale,  has  its  whole  vertical  face  marked  with  scratches  that  have  a  descending 


CENOZOIC    TIME  —  QUATERNARY.  955 

course  of  about  25°  to  30°.      The  narrow  lake  trends  about  S.  by  W.,  not  far  from  the 
direction  of  movement  in  the  ice-sheet  over  the  region. 

Over  Manitoba,  the  following  courses  of  scratches  are  reported  by  S.  B.  Tyrrell  : 
About  Lake  Manitoba,  S.  to  S.  13°  E.  ;  about  Lake  Winnipegosis,  S.  13°  E.  to  S.  58°  W. ; 
about  Swan  Lake,  west  of  Winnipegosis,  S.  48°-53°  W. ;  on  Red  Deer  River,  S.  68°- 
78°  W. ;  Grand  Rapids  on  the  Saskatchewan,  S.  2°-62°  W.  ;  at  Roche-rouge,  S.  12°  W.  ; 
Cedar  Lake,  S.  19°-39°  W.  The  southward  and  southeasterly  course  is  evidently  due  to 
a  valley  movement  along  the  lakes.  For  others,  over  the  interior  of  North  America,  see 
Upham's  paper  on  Lake  Agassiz,  Can.  Geol.  Bep.  for  1888-1889,  and  other  Reports  of  the 
Canada  Geological  Survey. 

In  the  use  of  scratches  to  determine  direction  of  flow,  the  directions  on  page  942 
should  be  observed.  When  scratches  having  different  courses  occur  at  the  same  locality, 
it  is  also  to  be  remembered  that  direction  of  general  movement  in  the  ice-mass  depends 
on  the  slope  of  the  upper  surface,  as  is  true  for  any  liquid  ;  and  therefore  that  the  thinning 
of  the  ice  from  melting  may  change  the  direction  of  movement  at  bottom.  But  where 
thinning  has  diminished  the  slope  of  the  ice-surface  below  the  angle  required  for  flow, 
the  ice  is  that  only  of  a  dead  glacier. 

Bowlders  were  observed  in  Northampton  and  Monroe  counties,  Pa.,  by  Lewis 
and  Wright,  which  must  have  come  from  the  Adirondacks.  One  of  them  of  "  labradorite 
syenyte,"  2i'  in  diameter,  was  found  in  Upper  Mount  Bethel  just  south  of  Kittatinny 
Mountain;  another,  similar,  measuring  4'  x  3'  x  3',  on  the  moraine  near  Taylorsburg,, 
between  Kittatinny  Mountain  and  Pocono  Mountain ;  and  another,  of  gray  Adirondack 
granite,  containing  magnetite,  near  Fork's  Station,  in  Paradise,  5  miles  north  of  Pocono 
summit,  at  a  height  of  1550' ;  and  bowlders  of  gneiss  are  abundant  over  the  Pocono 
plateau,  2000'  above  sea  level.  (Geol.  Eep.  Pa.,  vol.  Z,  On  the  Terminal  Moraine  in  Pa. 
and  N.  Y. ,  by  H.  C.  Lewis,  1884,  with  an  Appendix  on  the  Terminal  Moraine  in  Ohio  and 
Kentucky,  by  G.  F.  Wright.) 

General  direction  of  flow. " — From  the  Laurentlde  ice-plateau,  or  that 
which  covered  the  Canada  watershed  and  extended  westward  and  north- 
ward, the  flow  was  not  only  eastward  and  westward,  but  also  northward,  from 
its  northern  part  toward  the  Arctic  seas ;  and  along  the  great  eastward  bend 
in  the  plateau  over  Canada  south  of  Hudson  Bay  to  Labrador,  it  was  south- 
westward  on  the  western  part,  and  farther  east,  southward  and  southeast- 
ward. The  observed  courses  of  transported  stones  and  lines  of  abrasion  are 
the  means  of  locating  the  summit  region  of  the  ice-plateau. 

High  mountains  outside  the  plateau  also  influenced  the  flow,  for  they  are 
regions  of  greatest  precipitation.  The  White  Mountains,  Green  Mountains, 
and  Adirondacks,  combined  into  a  common  plateau  by  the  ice,  was  one 
of  these  mountain  regions,  apparently  determining  southeastward  directions 
of  movement  over  New  England  and  southwestward  over  Pennsylvania  and 
much  of  New  York.  In  western  New  York  and  over  the  higher  parts  of 
Ohio  the  flow  was  again  east  of  south ;  but  beyond  Indiana  to  Dakota  the 
direction  was  in  general  southward  and  southwestward,  as  if  from  an  ice- 
plateau  in  the  Lake  Superior  region. 

But  above  these  plateaus,  and  farther  north,  dominated  the  higher 
Laurentide  ice-plateau,  which  appears  to  have  been  the  chief  source  of 
movement  southward  for  the  region  during  the  time  of  maximum  ice,  although 
there  were  many  subordinate  sources. 


D56  HISTOKICAL   GEOLOGY. 

In  the  glaciated  area  along  the  Rocky  Mountain  Range  of  British  America 
•called  the  "  Cordillera  area  "  by  G.  M.  Dawson,  and  the  region  between  this 
range  and  the  coast,  the  movement  of  the  ice  was  for  the  larger  part  south- 
eastward. But  a  northern  part,  north  of  60°-65°  N.,  moved  northwestward, 
.and  central  portions  escaped  westward  through  passes  in  the  mountain 
ranges  near  the  coast  (G.  M.  Dawson) . 

About  the  Wisconsin  driftless  area  the  scratches  over  the  surface  east  of 
it,  according  to  Chamberlin  and  Leverett,  mostly  point  westward  or  west- 
south  westward,  toward  the  area,  in  concordance  with  the  fact  that  the  area 
was  that  of  a  depression  in  the  ice-sheet,  so  that  the  slope  of  the  ice-surface 
was  toward  it.  And  to  the  south  of  it  the  same  course  is  continued,  show- 
ing that  the  depression  in  the  ice-sheet  was  lengthened  southward.  But  on 
the  same  authority,  there  was  also  an  interval  when  the  movement  south 
•of  the  area,  as  proved  by  the  transported  material,  was  reversed,  or  from 
Iowa  into  Illinois. 

To  the  eastward,  the  ice-sheet,  when  at  its  maximum  stage,  extended 
southward  in  a  broad  convexity  or  lobe  over  New  England  and  New  York. 
{See  map.)  This  was  due  in  part  to  the  general  topographic  form  of  the 
surface,  but  more  directly  to  the  position  and  height  of  the  White  Mountain 
and  Adirondack  ice-plateau,  the  head  of  the  ice-movement.  But  besides  this, 
Pennsylvania  and  southwestern  New  York  were  under  the  lee  of  the  ice- 
covered  Adirondacks  and  Catskills,  and  it  is  for  this  reason,  apparently,  that 
over  the  former  state  the  southern  limit  took  its  northwestward  course  into 
New  York  ;  a  course  which  has  no  correspondence  with  the  lines  on  a  modern 
rain  chart. 

The  flow  was  also  guided  in  part  by  large  lake  depressions,  and  especially 
when  these  were  near  the  border,  as  was  the  case  during  the  progress  of  the 
•Glacial  period.  Moreover,  the  flow  of  the  lower  ice  was  always  influenced 
locally  by  the  topographic  form  of  the  surface,  and  particularly  by  the 
•courses  of  large  river  valleys  as  stated  on  page  247.  Such  valleys  have  their 
valley  drift  and  scratches,  as  proof  of  the  valley  movement.  This  movement, 
as  in  the  case  of  that  along  the  Connecticut  River  valley,  has  sometimes  been 
attributed  to  a  local  glacier  after  the  retreat  of  the  ice-sheet.  But  the  Con- 
necticut, for  the  200  miles  from  Haverhill,  N.H.,  to  the  Sound,  has  a  pitch  of 
only  two  feet  a  mile.  More  than  50  feet  a  mile  would  be  required  for  move- 
ment, and  this  would  demand  a  height  at  Haverhill  of  10,000  feet,  which 
could  not  be  unless  the  greatest  of  the  earth's  mountains  existed  there.  A 
length  of  200  miles  in  a  local  glacier  along  an  open  valley  is  more  than 
three  times  greater  than  now  exists. 

The  Connecticut  River  valley  is  a  good  example  of  the  effect  of  large  valleys,  oblique 
in  direction  to  the  general  movement  of  the  ice,  in  carrying  off  the  lower  ice  which  lay 
in  the  depression,  while  the  upper  ice  continued  part  way,  or  wholly,  across  it.  Its  direc- 
tion along  southern  Vermont  and  over  Massachusetts  and  Connecticut  to  New  Haven  is  S. 
8°-16°  W.,  while  that  of  the  general  glacier  movement  was  S.  30°-50°  E.  The  flowing 
bottom  ice,  within  the  confines  of  the  valley,  carried  along  for  distribution  almost  solely 


CENOZOIC    TIME  —  QUATERNARY.  957 

stones  from  valley  rocks  —  chiefly  trap  and  red  sandstone  —  and  made  scratches  in  the 
direction  of  the  valley,  while  the  upper  ice  left  similar  evidence  of  its  direction  of  flow, 
S.  30°-50°  E.,  in  the  distribution  of  bowlders  from  the  region  west  of  the  valley.  These 
bowlders,  in  general,  were  dropped  in  the  valley,  they  sinking  in  the  ice  till  within  the 
valley  flow  ;  so  that,  in  such  a  case,  they  prove  only  that  the  flow  characterizing  the  upper 
ice  continued  part  of  the  way  across  the  Connecticut  valley. 

Other  examples  of  valley  ice-streams  are  those  of  the  Merrimac,  N.H.,  of  the 
Winooski  Valley  in  Vermont,  and  that  of  Lake  Champlain,  as  proved  by  the  glacial 
scratches  observed  by  C.  H.  Hitchcock. 

Transportation  and  Deposition. 

1.  Gathering  of  material,  and  its  condition.  —  The  ice-sheet  received  little 
material  from  avalanches,  that  is,  through  falls  of  ice  or  stones  from  pre- 
cipitous declivities  or  overhanging  cliffs,  except  toward  its  front  margin;, 
for,  in  the  maximum  stage  of  the  ice,  it  covered  all  the  mountains,  except 
the  highest.  The  moving  mass  carried  debris  for  the  most  part,  not  from 
the  slopes  and  summits  of  emerged  ridges,  but  from  those  underneath  it, 
against  or  upon  which  it  rested,  and  chiefly  from  the  slopes  and  summits  of 
such  ridges  rather  than  from  level  surfaces.  It  obtained  its  load  by  abrad- 
ing, plowing,  crushing,  and  tearing  from  these  underlying  slopes  and 
summits.  It  took  up  the  loose  earth  and  stones,  abraded  the  hard  rocks, 
plowed  into  the  soft,  and  broke  and  tore  off  small  and  large  bowlders  from, 
the  fissured  or  jointed  rocks. 

The  ice-mass  was  a  coarse  tool;  but  through  the  facility  with  which  it 
broke  and  adapted  itself  to  uneven  surfaces,  it  was  well  fitted  for  all  kinds 
of  shoving,  tearing,  and  abrading  work.  Moreover,  it  was  a  tool  urged  on 
by  enormous  pressure.  A  thickness  of  1000  feet  corresponds  to  at  least 
50,000  pounds  to  the  square  foot.  The  ice  that  was  forced  into  the  openings 
and  crevices  in  the  rocks  had  thereby  enormous  power  in  breaking  down 
ledges,  prying  off  bowlders,  and  in  abrading  and  corrading.  In  contrast, 
the  ice  of  an  Alpine  glacier  has  a  thickness  ordinarily  of  but  300  to  500 
feet. 

It  gathered  little  from  the  lowest  parts  of  the  narrower  valleys,  because 
of  the  subglacial  stream  often  present  there,  and  the  open  space  in  the  ice 
above  it  —  the  ice  resting  itself  in  such  cases  mostly  against  the  sides  of 
the  valley. 

Where  the  fissured  rocks  were  hard,  large  stones  were  taken  up,  some 
of  them  hundreds,  and  occasionally  thousands,  of  tons  in  weight.  But  in 
regions  of  soft  rocks,  such  as  shale,  slate,  and  fragile  sandstone,  and  of  rocks 
easily  decomposed,  the  material  obtained  was  merely  sand,  earth,  or  small 
stones  that  were  readily  reduced  to  earth.  Over  areas  of  great  extent, 
therefore,  the  glacier  moved  on  with  little  besides  the  finer  debris  to  dis- 
tribute. Such  facts  suggest  a  reason  for  the  frequent  absence  of  stones  and 
large  bowlders  from  large  parts  of  a  glaciated  region. 

In  consequence  of  this  subglacial  method  of  gathering  materials,  nearly 
all  transported  debris  of  the  glacier  was  confined  at  first  to  its  lower  part, 


<958  HISTORICAL   GEOLOGY. 

within  500  to  1500  feet  of  the  bottom.  It  was  intraglacial,1  as  now  in  Green- 
land ;  there  was  in  general  no  superglacial  drift  over  the  ice-sheet.  The  local 
exceptions  to  this  occur  over  the  melting  lower  margin ;  for  a  short  distance 
•about  some  "Nunatak"  (page  240),  where  local  melting  had  favored  the 
growth  of  alpine  Algae ;  and  in  regions  reached  by  the  dust  of  the  drifting 
winds.  Even  the  stones  and  gravel,  taken  up  from  the  bottom  over  which  the 
ice  moved,  might  have  been  carried  upward  along  oblique  planes  of  bedding 
or  lamination  into  the  ice-mass. 

A  paragraph  from  the  chapter  on  Glaciers  (page  246)  is  here  repeated  because  of  its 
•apparent  importance  in  connection  with  the  accumulation,  transportation,  and  deposition 
of  the  drift. 

The  slipping  of  the  ice  along  planes  of  bedding  or  straticulation  like  that  of  the  blue 
bands  has  been  shown  by  Forel  to  be  a  fact  in  several  glaciers,  among  them  the  Bossons 
Glacier  at  Chamouni.  In  the  lower  part  of  a  glacier  these  planes  have  a  dip  upstream ; 
and  as  a  consequence,  the  mass  of  the  glacier,  as  it  moves  down  the  valley,  rises  by  slip- 
ping along  one  or  more  of  the  planes  of  lamellar  structure.  Forel  observes  that  the  fact 
explains  the  difference  of  velocity  between  the  upper  and  lower  beds  of  the  ice ;  the  little 
movement  at  the  extremity  of  a  glacier;  the  reappearance,  at  the  surface,  of  bodies 
buried  in  the  interior  of  the  glacier ;  and  the  preservation  of  the  thickness  of  the  ice  at 
the  lower  extremity,  notwithstanding  the  annual  loss  from  melting.  The  cause  must 
have  great  influence  over  the  direction  of  crevasses,  and  in  all  adjustments  to  resistances. 
He  states  further  that  at  the  Glacier  of  Hochsbalm,  a  frontal  moraine  was  formed  in  1884, 
by  the  slipping  of  a  bed  of  clean  ice  over  an  old  bed  of  debris-covered  ice.  (Arch.  Phys. 
Nat.  Geneve,  1889,  xxii.,  276,  and  Am.  Jour.  Sc.,  1889,  xxxviii.,  412.) 

Besides  taking  up  material  for  transportation,  the  glacier  pushed  along 
bowlders  and  gravel  wherever  its  mass  rested,  and  especially  where  there 
was  a  rocky  surface  at  shallow  depth  below  for  it  to  slip  over  ;  and  the  loose 
material  gathered,  besides  serving  for  abrasion,  made  a  prominent  part  of  the 
ground-moraine  here  and  there  in  progress  of  accumulation. 

The  uneasy  glacier  stream  —  uneasy  because  forced  to  make  unceasingly 
new  adjustments  to  the  uneven  surface  underneath  it  —  carried  on  the  work 
of  corrasion  among  the  transported  stones  with  vastly  greater  force  than 
running  water,  because  the  ice  had  a  firm  hold  on  the  stones  and  was  plied  by 
pressure  of  vast  amount.  It  was  a  wonderfully  efficient  rock-mill.  The 
stones,  hard  or  soft,  had  their  angles  and  surfaces  rounded,  and  then  were 
gradually  reduced  to  sand,  earth,  and  rock-flour.  Owing  to  this  wearing  out 
of  the  stones,  the  drift  in  any  region  seldom  contained  stones  gathered  from 
points  more  remote  than  the  last  fifty  miles  of  travel.  Shaler  states  that 
the  stones  and  bowlders  on  Nantucket  were  all  gathered  by  the  ice  east  of 
Narragansett  Bay. 

It  is  not  surprising  that,  in  Illinois,  Indiana,  and  Iowa,  where  the  distance 
of  travel  from  any  good  gathering-place  was  great,  stones  in  the  drift  should 
be  few,  and  be  almost  confined  to  the  hardest  kinds,  as  those  of  chert ;  that 
the  southern  ice-limit  should  in  some  parts  have  no  well-defined  moraine ; 

1  The  term  englacial,  used  by  some  writers,  is  not  here  adopted  because  it  is  half  Greek. 
Intraglacial  accords  with  Latin  usage. 


CENOZOIC   TIME  —  QUATERNARY.  959 

that  clay  makes  a  part  of  till,  and  sometimes  interlaminating  beds ;  and  that 
half-decomposed  rock-flour,  fitted  to  make  loess,  should  have  been  contributed 
so  abundantly  to  the  Mississippi  and  its  tributaries. 

The  smaller  traveled  stones  were  sometimes  ground  smooth  on  several 
sides,  and  thus  facetted,  so  as  to  resemble  human  flint  implements.  Shaler 
mentions  the  frequent  occurrence  of  such  facetted  stones  on  Nantucket,  and 
W.  P.  Blake  has  found  many  over  Mill  Rock,  near  New  Haven,  Conn. 

The  process  of  decomposition  went  forward  rapidly  because  the  stones 
were  in  a  moist  place,  and  the  needed  air  penetrated  all  glaciers.  Moreover, 
through  the  carbonic  acid  present  in  the  ice,  as  it  is  present  in  all  rain  or 
snow,  decomposition  of  other  kinds  went  forward,  and  especially  that  of 
changing  the  finely  powdered  feldspar  to  clay  (page  129).  The  microscopic 
vegetation  not  uncommon  in  glacier  ice,  including  that  of  Greenland,  may, 
through  its  decay,  have  afforded  additional  carbonic  acid,  and  also  organic 
acids  for  the  work  of  decomposition. 

There  is  little  of  this  clay  made  in  the  region  of  the  Alps,  but  it  was 
almost  universal  when  the  continental  ice  flowed  over  regions  where  crystal- 
line rocks  were  to  be  had ;  and  the  distribution  of  clay  in  great  beds  over 
glaciated  areas,  as  well  as  in  the  bowlder  clay,  is  thus  accounted  for. 

The  invading  ice  in  its  first  movement  trod  down  the  forests  and  carried 
off  the  broken  trunks ;  and  some  trunks  and  stumps  and  eddy-like  gatherings 
of  leaves  in  the  till  or  bowlder  clay  of  Ohio,  Indiana,  Illinois,  and  other 
states  west  may  have  thus  been  gathered.  The  accumulation  of  soil  and  the 
growth  of  forests  over  the  debris  that  accumulates  on  the  melting  margin  of 
a  glacier,  as  on  the  St.  Elias  glacier  (page  239),  illustrates  a  common  process 
of  the  Ice  age. 

2.  Transportation.  —  In  the  work  of  transportation  both  ice  and  water 
were  concerned.  Melting,  through  the  warmer  season,  and  copious  rains  sup- 
plied the  water.  The  glaciers  of  the  Alps  and  Greenland  teach  that  super- 
glacial  lakes  and  streams  may  thus  have  been  made,  which  contributed  water 
to  sub-glacial  rivers. 

The  distance  of  transportation  by  the  glacier  varied  from  10  miles  or  less 
to  500 ;  and  more  examples  of  distant  travel  would  exist  if  stones  did  not 
wear  out.  Native  copper  has  the  advantage  of  stone,  and  some  of  its  masses 
made  a  journey  of  at  least  450  miles,  as  stated  on  page  952. 

The  direction  of  travel  is  sometimes  indicated  by  the  occurrence  of  long 
trains  of  stones  leading  off  from  the  ledge  or  peak  which  afforded  them.  A 
hill  of  hard  quartzose  chloritic  rocks  on  the  borders  of  Lebanon  and  Canaan, 
in  Rensselaer  County,  N.  Y.,  was  the  parent  source  of  the  "  Eichmond  "  train 
of  large  stones  that  crosses  the  Taconic  Kange  into  Massachusetts,  and  is 
continued  on  over  Richmond  and  Lenox  into  Tyringham  (S.  Reid,  1842,  E. 
Hitchcock,  1844,  E.  R.  Benton,  1878). 

Some  of  the  transported  bowlders  exceed  1000  tons  in  weight.  The 
"Churchill  Rock"  at  Nottingham,  N.H.,  described  by  C.  H.  Hitchcock,  is  62, 
40,  and  40  feet  in  its  diameters,  and  is  estimated  to  weigh  about  6000  tons. 


960  HISTORICAL   GEOLOGY. 

The  "  Green  Mountain  Giant  "  at  Whitingham,  Vt.,  weighs  about  3000  tons;. 
"W.  0.  Crosby  has  described  a  bowlder  on  the  eastern  border  of  New  Hamp- 
shire having  diameters  of  30,  40,  and  75  feet,  and  weighing  6000  tons.  In 
Ohio  there  is  one  16  feet  thick,  which  covers  three  fourths  of  an  acre. 

From  southwestern  Vermont,  the  granite  of  a  high  hill,  between  Stamford  and  Pownal, 
which  is  almost  as  high  as  the  Green  and  Hoosac  Mountains  lying  to  the  east  and  south- 
east, was  carried  southeastwardly  over  the  western  sides  of  these  mountains,  nearly  across 
the  state  of  Massachusetts. 

Iron  Hill  of  Cumberland,  R.I.,  furnished  bowlders  of  iron  ore  for  the  country  south  of 
Providence,  to  the  Newport  region,  thirty-five  miles  distant,  and  thence  south  of  east,  as. 
shown  by  Shaler,  to  Gay  Head  on  Martha's  Vineyard. 

Large  bowlders  are  scattered  widely  over  eastern  Long  Island,  which  are  the  crystal- 
line rocks,  trap,  and  sandstone  of  New  England  ;  and  others,  over  western  Long  Island, 
which  are  from  the  Palisades  and  heights  along  the  Hudson  Kiver.  South  of  Lake 
Superior,  there  are  bowlders  which  have  come  from  the  north  shore  of  the  lake. 

In  this  movement  of  the  glacier  the  transported  stones  and  earth,  at  first 
intraglacial,  have  sometimes  become  superglacial,  about  any  emerged  or  nearly 
emerged  mountain  peak,  as  in  Greenland  about  the  "  Nunataks "  (page 
249).  And  after  serving  as  a  superglacial  moraine  for  awhile,  the  whole  may 
have  sunk  away  through  crevices  or  crevasses  to  intraglacial  positions  again. 
The  ice,  as  it  moves  up  a  long  slope  of  a  hill  or  mountain-side,  slips  over  the- 
rising  surface,  and  carries  its  load  with  it ;  and  on  many  slopes  such  stones 
are  found  at  a  level  1000  to  3000  feet  or  more  above  their  source.  Mount 
Katahdin  in  Maine  has  many  bowlders  on  its  northern  face  derived  from; 
the  Devonian  rocks  of  the  low  country  to  the  north,  3000  feet  below  it  in 
level,  which  were  thus  carried  up  the  mountain.  Stones  from  a  low  level! 
in  the  ice  may  thus,  if  not  stranded  on  the  slopes,  use  the  high  level  for 
further  travel  or  continue  on  at  their  original  level. 

3.  Deposition.  —  The  deposition  of   the  transported  material  took  place 
(1)  through  crevasses  and  crevices,  aided  by  descending  waters  from  the- 
superficial  lakes  or  streams ;   (2)  from  the  melting  bottom  of  the  glacier ; 
(3)  from  the  melting  always  in  progress  along  the  front  of  the  glacier,, 
which  was  augmented  during  retreats.     Moreover,  the  material  pushed  along 
by  the  glacier  was  an  important  addition  to  the  moraine-making  debris  set 
free  by  the  melting  ice.     Great  bowlders  would  be  the  first  landed  from  the 
decaying  ice-mass ;  yet  large  and  small  stones,  earth  and  clay,  are  so  mingled 
in  the  till  that  the  term  bowlder-day  is  well  applied  to  the  larger  part.     The 
stones  of  the  till  show  their  glacier  origin  usually  by  marks  of  abrasion. 
But  flowing  glacial  waters  carrying  sand  have  often  worn  smooth  the  glacier- 
dropped  stones  and  bowlders.     The  subglacial  waters,  wherever  in  gentle  flow 
along  their  valleys,  may  have  made  part  of  the  local  deposits  of  clay  and  sand, 
while  others  were  made  by  the  waters  flowing  away  from  the  front. 

4.  The  terminal  moraine  or  southernmost  Ice-limit. — The  terminal  moraine 
marks  the  limit  of  the  ice-sheet  when  it  was  of  maximum  extension,  and 
therefore  when  of  maximum  power  for  work,  whether  at  abrasion,  corrasion,, 


CENOZOIC   TIME — QUATERNARY.  961 

or  transportation.  Along  portions  of  the  line  in  western  Pennsylvania,  Ohio, 
and  Indiana,  the  amount  of  drift  material  is  small,  so  that  it  is  sometimes 
called  the  attenuated  margin  of  the  drift.  But  at  some  places  in  Ohio  the 
terminal  till  is  stated  by  Wright  to  be  100  feet  thick  or  more.  In  southern 
Illinois,  Williamson  County,  the  thickness  at  the  limit  averages,  according 
to  Chamberlin  and  Leverett,  20  feet,  and  in  some  places  is  50  feet  thick ;  and 
striation  is  deep  in  the  vicinity,  proving  the  action  of  a  land  ice-mass.  In 
Kansas  and  Missouri,  the  most  southern  portion  of  the  drift,  there  are 
bowlders  of  considerable  size.  To  the  eastward,  in  eastern  Pennsylvania, 
near  South  Bethlehem,  the  Durham  and  Eeading  Hills,  665  to  900  feet  high, 
have  bowlders  and  scratches  at  all  altitudes. 

Far  eastward,  south  of  New  England,  in  the  region  of  greatest  precipi- 
tation, the  terminal  moraine  extends  along  the  islands  from  Nantucket, 
Martha's  Vineyard,  by  Block  Island,  to  the  south  part  of  Long  Island.  On 
this  island,  west  of  the  Shinecock  Hills,  there  is  a  long  interval  of  stratified 
sands ;  and  then  at  the  western  extremity  of  the  island  the  drift  is  again  at 
the  surface,  and  continues  to  Staten  Island  and  New  Jersey.  The  deposits 
are  coarse,  100  to  200  feet  or  more  in  thickness,  partly  stratified  in  places, 
and  carry  large  bowlders. 

Ten  to  twenty  miles  north  of  the  line  just  described,  from  Cape  Cod  along  the  Elizabeth 
Islands  and  the  shores  of  Khode  Island  and  Connecticut,  between  Narragansett  Bay  and 
Watch  Hill,  and  then  along  Fishers  Island  and  the  north  side  of  Long  Island,  there  is 
a  second  range  of  terminal  moraine,  as  first  announced  by  Upham.  The  islands  are  not 
drift  made  ;  for  they  had  an  earlier  existence,  as  subjacent  Cretaceous  and  other  terranes 
show ;  and  they  may,  therefore,  have  determined  the  twofold  subdivisions  of  the  drift. 
Yet  it  is  more  probable  that  there  are  two  lines  of  moraines,  and  that  only  the  more 
southern  is  to  be  taken  as  the  terminal  moraine,  or  that  at  the  limit  of  maximum  exten- 
sion. Nothing  is  known  to  exist  over  the  sea  bottom  south  of  Long  Island  to  indicate  a 
still  more  southern  line,  although  the  surface  for  25  miles  or  more  seaward  was  part  of  the 
dry  land. 

This  epoch  of  the  advance  in  the  Glacial  period  was  probably  of  great 
length.  The  vastness  of  the  area  covered  with  ice,  the  thickness  of  the  ice- 
mass,  and  its  accumulation  even  over  the  dry  Continental  Interior,  lead 
to  this  conclusion;  and,  as  has  been  shown,  the  attenuation  of  the  drift 
along  much  of  the  front  is  not  evidence  against  it ;  for,  notwithstanding 
this,  there  was  slow  transportation  to  the  limit. 

The  terminal  moraine,  or  southernmost  limit  of  the  ice,  was  located  along  the  islands 
south  of  New  England  first  by  Upharu  and  Clarence  King ;  and  along  the  coast  east  of  Watch 
Hill  (which  is  a  continuation  of  Fishers  Island)  by  C.  King.  Its  location  over  New  Jersey 
was  made  out  by  G.  H.  Cook  and  F.  Smock. 

2.   Epoch  of  the  First  Retreat. 

1.   Distance  of  the  Retreat.  —  The  evidence  of  a  retreat  of  the  ice-front 
is  afforded  by  the  condition  of  the  till  and  other  glacial  deposits  over  the 
region  of  the  retreat,  and  by  the  record  of  a  long  halt  at  the  close  in  the 
DANA'S  MANUAL  —  61 


962  HISTORICAL    GEOLOGY. 

existence  ordinarily,  as  the  northern  limit  of  the  retreat,  of  a  more  or  less 
prominent  belt  or  line  of  moraine. 

The  course  of  this  moraine-line,  as  mapped  chiefly  by  Chamberlin  and 
Leverett,  is  shown  on  the  map  (Fig.  1548) .  It  is  the  line  lettered  B,  B,  B, 
and  is  designated  the  moraine  B,  or  moraine-line  B.  The  belt  of  land  laid 
bare  by  the  retreat  extended  westward  to  the  Continental  Interior ;  no  such 
retreat  has  yet  been  recognized  west  of  the  Rocky  Mountain  region.  In 
Illinois,  the  moraine  B  includes  the  Shelbyville  moraine  of  Chamberlin  and 
Xieverett,  which  passes  near  Shelbyville  in  central  Illinois,  and  probably  the 
Altamont,  of  Upham,  in  central  Iowa,  the  southernmost  of  the  series  in  that 
state. 

The  width  of  this  belt  varies  from  10  miles  and  less  to  more  than 
300  miles.  It  is  least  along  the  islands  south  of  New  England,  and 
through  New  Jersey  and  Pennsylvania,  where  the  precipitation  was  greatest 
—  so  great  that  the  annual  accumulation  of  ice  fell  but  little  behind  the 
amount  lost  by  melting.  But  farther  west,  from  western  Ohio  to  the  Conti- 
nental Interior,  the  width  increases  with  the  decrease  in  the  amount  of 
precipitation.  In  western  Ohio  and  Indiana,  the  mean  width  is  40  miles  ; 
from  Illinois  to  northwestern  Kansas,  it  increases  from  150  to  275  miles ; 
and  the  driftless  area,  lying  chiefly  in  Wisconsin,  is  made  part  of  a  much 
larger  iceless  area. 

From  Kansas  in  a  northwestward  direction,  the  region  of  melting 
stretched  northwestward  over  the  district  of  Assiniboia  to  the  Saskatchewan, 
or  1000  miles,  if  not  beyond  this ;  and  as  the  dotted  line  (Fig.  1548)  is  the 
limit  of  transportation  of  drift  from  the  eastward,  and  B  B  that  of  the 
morainic  limit  of  the  melting  (along  the  Coteau  du  Missouris  and  the  third 
Prairie  level,  in  continuation  of  the  Coteau  des  Prairies,  as  laid  down  by 
G.  M.  Dawson),  the  width  of  the  area  laid  bare  in  British  America  is  full 
300  miles.  The  district  of  the  Winnipeg  region  was  still  under  ice. 

Between  Cape  Cod  and  northeastern  Kansas  the  retreat  was  from  the 
south,  northward,  but  in  British  America  it  was  from  the  west,  eastward,  and 
east-northeastward ;  that  is,  it  was  from  the  borders  of  the  great  ice-sheet 
inward.  Along  the  Coteau  des  Prairies,  the  retreat  from  west  to  east  was 
small,  because  the  region  west  of  that  part  of  the  Missouri  was  bare  through 
all  the  epoch  of  maximum  ice  owing  to  drought  and  heat. 

South  of  New  England  the  southernmost  line,  AA,  from  Nantucket  to  Perth  Amboy 
is  but  a  few  miles  from  that  of  the  moraine  B  situated  along  the  inner  range  of  islands, 
the  coast  west  of  Narragansett  Bay,  Fishers  Island,  Peconic  Bay,  and  the  north  half  of 
Long  Island  westward.  At  the  head  of  Peconic  Bay  the  moraines  of  the  north  and  south 
sides  of  the  bay  blend  with  one  another.  It  is  not  certain  that  the  moraine  of  the 
southern  limit,  or  that  of  maximum  ice,  was  not  outside  of  these  islands,  as  it  was  prob- 
ably outside  the  existing  shore  line  to  the  east  of  New  England,  Georges  Shoal  being 
probably  on  or  near  the  limit.  The  retreat  from  this  eastern  limit  was  probably  to 
some  line  now  under  water ;  for  the  moraine  on  Cape  Ann,  north  of  the  harbor  of 
Boston,  has  been  shown  by  Tarr  to  be  part  of  the  east-and-west  moraine  extending 
westward  to  the  Connecticut. 


CENOZOIC   TIME  —  QUATERNARY.  963 

The  nearness  of  the  moraine-line  A,  or  the  southern  ice-limit,  to  that  of  moraine-line 
B  in  Pennsylvania  may  be  owing  to  the  fact  that  the  course  of  each  was  not  dependent 
on  the  isotherms,  but  on  the  leeward  position  of  the  region  with  reference  to  the  icy 
heights  to  the  northeastward  (page  956). 

2.  Deposition  and  distribution  of  drift.  —  With,  the  melting  and  retreat 
of  the  ice-sheet,  deposition  of  the  transported  material  went  forward  making 
a  covering  of  till  of  varying  thickness,  deposits  in  some  parts  of  clay  and 
rock-flour  over  and  within  the  till,  and  intercalated  deposits  also  of  soil, 
sometimes  with  remains  of  forests,  as  has  been  already  described.  Besides, 
the  escaping  waters  carried  away  material,  fine  and  coarse,  for  stratified  beds 
of  clay,  sand,  and  gravel.  The  older  till  over  Illinois  and  Indiana  has  usu- 
ally a  depth  of  about  20  feet.  In  southeastern  Indiana  and  southwestern 
Ohio,  according  to  Leverett,  it  was  followed  by  a  covering  of  soil  and  then 
a  deposit  of  clay  to  a  depth  of  several  feet;  and  as  the  clay  contains, 
according  to  an  analysis,  2-32  per  cent  of  potash  and  soda,  16  per  cent  of  it 
or  more  is  feldspar  in  grains.  The  beds  of  soil  and  the  forest-beds  in  glacial 
deposits  are  mostly  contained  in  those  that  were  made  during  this  retreat. 

1550. 


Upper  part  of  Moraine,  Dogtown  Commons,  Cape  Ann.     Shaler,  1889. 

The  moraine  ridge,  which  marks  the  limit  of  the  retreat,  consisting  chiefly 
of  gravel,  stones,  and  bowlders,  was  made  by  the  deposition,  along  the  front, 
of  material  brought  down  by  the  ice-sheet  during  a  long  halt.  It  indicates 
the  transporting  power  of  the  ice ;  and  as  the  moraine  in  Illinois  and  Iowa  is 
over  150  miles  north  of  the  southern  ice-limit,  the  surface  of  the  ice-sheet  may 
have  had  a  steeper  pitch  than  during  the  period  of  maximum  ice,  so  that 
transportation  went  on  more  rapidly,  while  corrasion  and  deposition  were  less 
effective  agencies  of  rock-wear.  The  halt  had,  as  usual,  its  advances  and 


964  HISTORICAL   GEOLOGY. 

recessions  ;  and  this  was  one  means  by  which  the  moraine  ridge  was  widened 
and  rendered  irregular  in  height  and  surface. 

The  foregoing  figure  of  part  of  a  moraine  on  Cape  Ann,  Mass.,  from  a 
paper  by  Shaler,  though  belonging  to  a  later  part  of  the  Glacial  history,  shows 
the  common  appearance  of  such  moraines  at  the  present  time. 

A  great  feature  of  the  epoch  was  the  amount  of  water  discharged, 
making  new  channels  by  erosion  and  giving  the  streams  in  the  region  of 
melting  great  transporting  and  eroding  powers.  The  Delaware,  Susque- 
hanna,  Ohio,  and  other  streams  were  flooded;  and  the  Mississippi  derived 
waters  not  only  from  the  Ohio  with  its  many  tributaries  and  from  the  icy 
heights  of  the  Rocky  Mountains,  but  also  through  the  Missouri  from 
British  America,  far  north  of  Montana,  perhaps  from  the  upper  portion  of 
the  Saskatchewan.  Distribution  of  the  transported  material  supplied  by 
the  melting  ice,  and  erosion  by  the  loaded  waters  went  forward,  therefore,, 
with  unwonted  energy. 

With  the  continent  at  its  high  level,  the  flooded  rivers  over  all  the  conti- 
nent dug  out  their  channels,  during  the  time  of  maximum  ice,  often  to  great 
depths ;  then  at  the  melting  the  channels  were  filled  with  till,  and,  over  the-, 
till,  with  fluvial  beds  of  sand  or  gravel.  The  Mississippi  valley  received  then 
its  earlier  deposits  of  loess,  over  lake-like  regions  along  its  course,  while- 
other  portions  of  the  valley  had  their  coarser  deposits. 

South  of  New  England,  the  retreat  was  short.  On  Long  Island,  then  probably  500  feet 
high,  the  eroding  waters  carried  off  seaward  the  terminal  moraine  of  the  south  shore  for 
70  miles  of  its  length,  and  dropped  till  over  the  denuded  surface  ;  then  later  waters  covered 
it  with  sand  and  fine  gravel ;  for  there  are  no  bowlders  or  till  to  be  seen  over  the  even 
slopes,  although  abundant  elsewhere  on  the  island.  So  also  the  waters  that  descended 
the  north  slopes  of  the  island  from  the  moraine  belt,  cut  out  of  the  morainic  accumulations, 
and  underlying  Cretaceous  formation  a  number  of  short,  steep  valleys,  and  left  them 
similarly  under  fluvial  sand-beds  as  the  top-dressing,  with  no  bowlders  over  their  surface  ;; 
and  the  valleys,  after  the  Champlain  subsidence  —  which  restored  the  waters  of  the  Sound 
to  their  place  —  became  the  deep  and  capacious  harbors  of  the  north  coast. 

During  the  epoch  when  the  Mississippi  was  receiving  waters,  by  the- 
Missouri,  from  the  melting  in  progress  through  a  thousand  miles  from 
south  to  north,  with  other  floods  from  the  ice  and  snows  to  the  east  and 
the  glacier  regions  in  the  Eocky  Mountains,  the  deposition  took  place,  of 
what  has  been  named  the  Lafayette  formation  —  the  Orange  sand  formation 
of  Hilgard.  As  shown  by  Hilgard,  the  Lafayette  was  a  widespread  flood- 
made  formation,  extending  along  the  great  valley  of  the  continent,  the 
Mississippi,  south  of  its  junction  with  the  Missouri,  from  southern  Illinois  to 
the  Gulf.  Its  eastern  border  passes  near  Cairo  through  western  Kentucky 
and  Tennessee,  and  the  northeast  corner  of  the  Mississippi,  and,  according 
to  L.  Johnson,  reaches  the  shore  of  Mobile  Bay  in  Alabama.  Its  western 
border  crosses  Arkansas  and  Louisiana  into  Texas. 

The  formation  is  described  as  consisting  mostly  of  rust-colored  or  reddish 
siliceous  sand-beds.  Near  the  great  river  channels,  notably  that  of  the 


CENOZOIC    TIME  —  QUATERNARY.  965 

Mississippi  on  either  side,  of  the  Tombigbee  and  Tennessee,  as  well  as  of 
the  Sabine,  there  is  a  steady  increase  of  gravel.  It  occasionally  contains, 
even  in  Mississippi,  stones  of  10  to  100  pounds  in  weight,  and  rarely  150 
pounds.  There  are  also  some  local  clayey  beds.  The  stones  show  that  the 
material  came  from  the  northward;  many  have  in  them  Paleozoic  fossils. 
The  beds  are  irregularly  stratified,  sometimes  structureless  for  20  feet  of 
thickness,  but  have  generally  the  Jlow-and-plunge  structure,  illustrated  in 
Fig.  63,  page  93.  The  facts  prove,  as  Hilgard  states,  that  there  was  a  vast 
and  violent  flow  of  waters  down  the  broad  Mississippi  valley,  bearing  an 
immense  amount  of  sand  and  coarser  detritus,  and  also  some  floating  ice 
for  the  transportation  of  the  larger  stones.  Hilgard  therefore  concluded 
that  it  muse  have  been  made  during  the  melting  of  the  ice,  while  the  conti-. 
nent  had  still  the  elevation  characterizing  the  Glacial  period.  These  condi- 
tions are  those  of  the  First  Retreat. 

There  were  cotemporaneous  depositions  from  streams  descending  the 
Atlantic  and  southern  slopes  of  the  then  snow-clad  Appalachians ;  and  large 
areas  of  the  Lafayette  formation  in  these  regions  and  elsewhere  have  been 
•defined  and  mapped  by  McGee. 

The  "Orange  sand  "  is  often  40'  to  100'  thick,  and  in  some  places  over  200'  according 
to  Hilgard,  and  toward  the  Gulf  it  has  still  greater  thickness.  In  an  Artesian  well,  near 
the  Calcasieu  River,  200  miles  west  of  New  Orleans,  beds  referred  to  the  Lafayette  are  450' 
thick,  beneath  160'  of  clay  of  the  Port  Hudson  group ;  and  at  New  Orleans  760'.  This 
thickness  along  the  Gulf  is  supposed  to  be  evidence  of  a  gradual  subsidence  of  its  bor- 
der to  the  great  depth  stated,  as  deposition  went  forward. 

The  actual  limit  of  the  formation  is  in  doubt  because  it  contains  no  fossils,  and  the 
criterion  usually  appealed  to  in  its  correlation,  — kinds  and  color  of  gravels,  — is  admitted 
to  have,  whatever  the  rock  series,  almost  no  value.  In  Texas,  some  beds  referred  to  the 
Lafayette  were  found  by  G.  D.  Harris  to  contain  Tertiary  fossils. 

In  his  early  account  of  the  formation,  Hilgard  stated,  on  the  authority  of  Tuomey  and 
LeConte,  that  the  formation  passed  from  Alabama  eastward,  around  the  higher  Appa- 
lachian highlands  into  the  Carolinas,  and  thence  north  to  Virginia  and  Maryland.  McGee 
described,  in  1888,  similar  beds  of  orange-colored  sands  and  clays  along  the  Appomattox 
River  and  other  points  in  Virginia,  and  also  others,  in  North  Carolina  and  beyond,  to  which 
he  gave  the  name  of  the  Appomattox  formation,  and  he  has  since  studied  the  beds  in  the 
Mississippi  valley.  He  argues  that  part  of  the  borders  of  the  Atlantic  and  Mexican 
Gulf  were  200'  to  800'  below  their  present  level  at  the  time,  making  the  beds  in  part 
marine.  No  marine  fossils  or  other  marine  relics  have  been  described  in  evidence  of  the 
submergence.  Moreover  the  formation  is  made  preglacial  by  McGee,  and  others. 

The  term  Lafayette  was  substituted  in  1892,  by  agreement,  for  the  older  names  of 
Orange  sand  and  Appomattox. 

Mr.  Hilgard's  last  paper  on  the  subject  is  in  the  Am.  Jour.  Sc.,  xliii.,  1892 ;  and 
Mr.  McGee's  first  on  the  Appomattox  in  Am.  Jour.  Sc.,  xxxv.,  1888,  and  his  last  on  the 
Lafayette  formation  in  vol.  xii.,  Eep.  U.  S.  Geol.  Surv.,  1892. 

3.  River  channels  filled  by  the  drift.  —  The  discharge  of  drift  from  the 
melting  glacier  sometimes  filled  up  and  blocked  river  channels  at  places, 
and  compelled  the  river  to  make  a  new  cut. 

The  Ohio  Elver,  according  to  Newberry,  formerly  had  a  more  southern 


966  HISTORICAL    GEOLOGY. 

route  around  the  Falls  near  Louisville,  which  it  lost  when  the  ice  extended 
to  its  southernmost  limit.  The  Falls  are  evidence  of  uncompleted  work  in 
subsequent  erosion  along  the  valley. 

It  is  held  by  some  investigators  of  the  drift,  and  prominently  by  Chamberlin,  that  the 
retreat,  instead  of  ending  along  the  line  of  the  moraine  above  described,  continued  until 
North  America  had  lost  the  chief  part  of  its  ice-sheet,  and  that  this  "  First  Glacial  Epoch  'r 
was  followed  by  a  second  advance,  of  which  moraine  B  was  the  terminal  moraine.  This 
view  is  sustained  on  the  ground  that  the  erosion  produced  during  the  interval,  the  inter- 
calation of  forest-beds  and  stratified  clays,  and  the  weathering  and  oxidation  of  the 
lower  tills  would  have  required  a  very  long  period  of  time.  It  is,  however,  an  important 
consideration  in  favor  of  the  shorter  retreat,  that  the  beds  eroded  were,  to  a  great  extent,, 
soft ;  that  the  amount  of  water  discharged  was  very  large ;  and  that  interstratified  sand- 
'  beds  and  forest-beds  are  such  as  modern  glaciers  are  now  producing.  The  arguments  and 
facts  favoring  the  theory  of  two  glacial  epochs  and  an  interglacial  are  presented  by  Cham- 
berlin in  his  Report  on  the  Geology  of  Wisconsin  ;  also  in  the  3d  and  7th  Reports  of  the 
U.  S.  Geol.  Surv.,  and  in  later  publications,  in  part  of  which  Leverett  is  joint  author  ;  by 
G.  M.  Dawson  in  his  Memoir  on  Rocky  Mountain  Geology  in  the  Trans.  Hoy.  Soc.  Canada, 
vol.  viii.,  1890,  etc.  Upham,  Hitchcock,  Wright,  and  others  favor  the  idea  of  a  continuous 
succession  of  recessions  and  halts  during  the  retreat. 

In  northeastern  Iowa,  according  to  McGee,  the  successive  glacial  deposits  are  :  (1)  the 
lower  till,  which  is  overlaid  by  stratified  sands  and  clays  (called  locally  gumbo)  ;  (2)  a. 
forest-bed,  with  unconformity  beneath  through  erosion  and  decomposition  ;  (3)  an  upper 
till  of  small  extent,  from  ice  that  was  of  short  duration  ;  (4)  the  loess,  which  contains 
some  bowlders,  and  graduates  at  base  into  the  till.  These  are  supposed  to  be  anterior  to- 
what  is  called  by  Chamberlin  the  Second  Glacial  Epoch.  The  loess  is  stated  to  have  been 
formed  in  an  ice-bound  lake,  which  he  names  Lake  Hennepin,  made  by  the  meeting  of 
two  lobes  of  ice,  advancing  either  side  of  the  Driftless  area.  The  loess  makes  a  fertile 
soil,  which  appears  to  be  evidence  that  there  was  abundant  vegetation  in  the  waters  in 
which  it  was  deposited,  and  thus  throws  doubt  over  the  presence  of  the  ice.  The  depau- 
perate condition  of  the  shells  shows  only  that  the  waters  were  cold  ;  and  their  great 
numbers,  that  conditions  of  growth  were  still  not  very  unfavorable. 

The  great  distance  of  transportation  of  glacial  drift  over  the  Continental  Interior  in 
British  America,  and  the  remarkable  uniformity  in  the  drift  deposits  over  the  vast  area  — 
u  250,000  square  miles  "  — has  led  to  the  view  that  the  region  was  submerged  under  fresh 
or  salt  waters,  and  that  floating  ice  was  the  transporter.  But  the  flow  over  such  waters, 
whether  tidal  or  not,  would  have  been  north  and  south,  and  not  across  the  area ;  and 
there  is  no  evidence  of  marine  conditions.  Moreover,  if  floating  ice  worked  there,  it  waa 
the  agent  to  the  south  in  the  United  States ;  and  this  is  not  in  accordance  with  the  facts 
there  observed. 

Land  and  freshwater  shells  and  other  fossils  of  the  loess  of  the  Mississippi  valley. — 
From  Galena,  111. :  Succinea  avara,  S.  obliqua,  Patula  striatella ;  Vallonia  pulchella, 
Limnophysa  humilis,  L.  desidiosa,  Pupa  contracta,  P.  muscorum  (R.  E.  Call).  —  From 
Davenport,  la. :  Succinea  avara,  S.  obliqua,  Helicina  occulta,  Pupa  fallax,  Helix  stria- 
tella. Also  tusk  and  molars  of  Elephas  primigenius  (Pratt). — From  Muscatine,  la.: 
Helix  striatella,  H.  fulva,  H.  pulchella,  H.  lineata,  H.  Cuperi,  Pupa  Blandi,  P.  quarti- 
caria,  P.  muscorum,  P.  simplex,  Succinea  avara,  S.  obliqua,  Helicina  occulta,  Limncea 
humilis,  Unio  ebenus,  U.  ligamentinus,  U.  rectus,  Melantho  subsolida,  Harcjaritina  con- 
fragosa.  Also  teeth,  bones,  and  antlers  of  Cervus  Muscatinensis  (Witter,  in  McGee's  Iowa}. 

From  Hickman,  in  Kentucky :  Conulus  chersina,  Hyalina  arborea,  Helicina  orbicu- 
lata,  H.  profunda,  Limncea  (Limnophysa)  desidiosa,  Mesodon  profundus,  M.  albolabris, 
Macrocyclis  concava,  Patula  alternata,  P.  perspectiva,  P.  solitaria,  Stenotrema  (Helix) 


GENOZOIC   TIME  —  QUATERNARY.  907 

monodon,  S.  hirsutum,  Treodopsis  appressa  (Wetherby).    The  species  are  all  of  kinds  now 
living  in  the  vicinity  of  the  several  localities. 

The  shells  of  the  Iowa  lake  are  much  below  the  natural  size  of  the  species,  showing 
the  depauperating  effect  of  the  cold  water  (McGee) ;  but  in  Kentucky  those  obtained  near 
the  Mississippi  are  larger  than  those  a  few  miles  to  the  eastward  (Loughridge). 


3.    Epoch  of  the  Final  Retreat. 

At  the  commencement  of  the  Final  Retreat,  as  shown  by  the  position  of 
moraine  B,  ice  still  covered  all  New  England,  all  ^Ne\v  York,  and  very 
nearly  all  that  part  of  Pennsylvania  that  was  covered  at  the  time  of  maxi- 
mum ice.  Bnt  in  Illinois  and  farther  west  to  Dakota,  the  First  Retreat  had 
left  bare  a  broad  belt,  which  extended  northwestward  into  British  America 
west  of  Manitoba. 

In  the  Final  Retreat  the  Mississippi  valley  was  still,  compared  with  the 
east,  the  region  of  most  rapid  melting,  and  for  the  same  reason  as  before  — 
the  warmer  and  drier  climate.  The  series  of  loop-shaped  moraines  in  Illi- 
nois and  Wisconsin,  and  that  in  Iowa  and  Minnesota,  mark  the  succession  of 
halts  and  recessions  in  the  course  of  the  retreat  northward  from  the  moraine 
line  B. 

The  Illinois  series,  as  described  by  Chamberlin  and  Leverett,  covers 
much  of  Illinois  and  passes  thence  into  Wisconsin ;  and  the  Iowa-Minnesota 
series,  as  mapped  by  Upham,  extends  first  northward  and  then  over  Minne- 
sota northeastward,  for  more  than  400  miles.  In  addition,  the  retreat  was 
going  on  from  the  moraine  line  B  in  Assiniboia,  north  of  Montana,  laying 
bare  much  of  Manitoba. 

In  the  Illinois  series  of  moraines,  there  is  near  Madison  the  noted  Kettle 
moraine  (KK  on  the  map),  more  than  200  miles  from  the  line  B,  or  that 
of  the  Shelbyville  moraine.  But  in  Indiana  the  distance  of  retreat  between 
the  moraine  line  B  and  the  line  K,  or  that  of  the  Kettle  moraine,  narrows 
rapidly ;  and  in  Ohio  it  is  very  small,  the  first  moraine  north  of  the  moraine 
B  being  regarded  by  Chamberlin  and  Leverett  as  probably  the  moraine  K. 
Farther  east,  moraine  K  extends  along  with  moraine  B  into  western  New 
York.  It  has  been  supposed  by  Chamberlin  to  pass  probably  south  of 
Cayuga  and  the  other  Finger  Lakes.  In  view  of  the  nearness  to  the  line  B 
in  Ohio,  it  may  be  questioned  whether  it  does  not  take  the  same  oblique 
course  with  it  through  Pennsylvania  and  become  there  indistinguishable 
from  it ;  and  the  same  also  farther  eastward  across  New  Jersey  and  south 
of  New  England.  If  this  is  the  right  view,  New  England  held  to  its  ice 
during  all  the  retreat  in  Illinois  of  200  miles,  precipitation  to  the  eastward 
adding  about  as  much  ice  as  was  lost  by  the  melting. 

Subsequently  the  final  retreat  involved  the  Eastern  States  as  well  as  the 
Mississippi  valley,  and  moraines  over  New  England  and  New  York  mark 
its  progress.  One,  as  described  by  R.  S.  Tarr,  crosses  Massachusetts  west  of 
the  Connecticut,  passing  south  of  Turner's  Falls,  Orange,  Royalston,  Win- 
chendon,  and  terminates  in  the  Cape  Ann  moraine  described  by  Shaler. 


$38  HISTORICAL   GEOLOGY. 

Three  or  four  others,  according  to  C.  H.  Hitchcock,  exist  in  Vermont  and 
New  Hampshire. 

The  moraines  made  on  this  final  retreat  bring  to  light  the  fact,  as 
observed  by  Chamberlin,  that  the  movements  of  the  ice-sheet  in  the  region 
of  the  Great  Lakes  became  largely  resolved  into  movements  along  lake- 
basins.  They  thus  bear  testimony  to  the  preglacial  existence  of  the  basins 
of  the  Great  Lakes.  The  Kettle  moraine  (KK)  is  concentric  with  the  out- 
line of  the  Green  Bay  trough,  a  western  arm  of  Lake  Michigan ;  a  Michigan 
moraine  borders  the  Lake  Michigan  basin ;  and  a  series  of  Erie  moraines, 
as  mapped  by  Leverett,  are  approximately  parallel  with  the  western  part 
of  the  Lake  Erie  basin.  Besides,  there  are  indications  of  a  Saginaw  glacier 
movement,  along  the  trough  of  Saginaw  Bay  on  the  west  side  of  Lake 
Huron,  as  an  outlet  for  the  ice  of  the  Lake  Huron  basin.  There  were  thus 
brought  to  view  more  or  less  distinctly,  as  melting  went  forward,  the  outline 
of  a  Green  Bay,  Michigan,  Saginaw  or  Huron  and  Erie  glacier. 

Lake  Ontario  and  Lake  Erie,  during  the  time  of  maximum  ice  and  long 
after  retreat  began,  were  crossed  by  the  ice  in  a  southward  direction,  the 
glacial  scratches  south  of  Ontario  having  the  direction  S.  8°-20°  E.,  and 
those  south  of  Erie  mostly  S.  20°-30°  E.  But  the  evidence  of  a  lake-basin 
movement  —  really  an  Erie-Ontario  movement —  is  sustained  by  scratches  at 
the  east  end  of  Ontario,  and  over  the  region  at  the  west  end  of  Erie.  In  the 
latter  region,  the  deep  moldings  in  the  limestone  of  Kelley  Island  have 
the  courses  S.  60°-80°  W.  (Newberry)  ;  and  west  of  the  lake  the  same  direc- 
tions prevail.  This  westward  flow  in  the  Erie  basin,  first  pointed  out  by 
Gilbert,  and  later  sustained  by  Chamberlin  and  Leverett,  must  have  been 
dependent  in  part  011  a  like  movement  in  Lake  Ontario,  for  the  supply  of 
ice  required  a  general  westward  slope  in  the  ice-surface  to  the  eastward; 
and  the  Adirondack  ice-region  was  its  probable  source.  Chamberlin  and 
Leverett  also  bring  forward  evidence  from  the  moraines  (see  map,  Fig.  1548) 
that  Lake  Erie  was  rid  of  its  ice  before  the  more  northern  Lake  Ontario. 

The  movement  along  the  troughs  of  Lake  Michigan  and  Green  Bay,  sug- 
gested by  the  moraines,  as  Chamberlin  points  out,  proves,  if  a  fact,  that  the 
ice  over  the  troughs  had  the  slope  at  surface  requisite  for  movement  and 
transportation.  The  length  of  Lake  Michigan  is  335  miles ;  and  hence,  if 
the  mean  slope  was  but  30  feet  per  mile,  the  height  of  the  ice-surface  at  the 
north  end,  above  that  at  the  south,  would  have  been  10,000  feet ;  and  two 
thirds  of  this  if  the  rate  were  but  20  feet  per  mile.  With  such  evidence  of 
a  southward  movement  there  is  no  satisfactory  proof  that  a  subsidence  was 
in  progress  to  the  north,  although  the  retreat  of  the  ice  had  even  reached  the 
Canadian  borders. 

The  Iowa-Minnesota  series  of  moraines  appears  to  indicate  a  like  move- 
ment, and  a  like  northeastward  rise  in  the  slope  of  the  ice-surface.  With 
the  retreat  of  the  ice  from  Minnesota,  the  ice  disappeared  from  much  of  the 
more  northern  Lake  Winnipeg  region ;  and  Lake  Winnipeg,  receiving  waters 
from  melting  ice  on  its  eastern  and  northern  borders,  as  well  as  from 


CENOZOIC    TIME  —  QUATERNARY.  969 

rivers  to  the  west,  then  began,  while  the  continent  over  this  interior  region, 
was  still  at  high  elevation,  its  discharge  by  the  Red  Eiver  of  the  North  into  the 
Minnesota,  and  the  Mississippi  became  emphatically  the  "  Great  Mississippi." 
It  was  at  this  time  of  the  departure  of  the  ice  from  the  lake  region  to 
the  country  north  of  Lake  Superior,  before  a  subsidence  had  made  much  if 
any  progress,  that  the  areas  of  the  Great  Lakes  were  fluvial  areas,  carrying 
on  vigorously  the  work  of  excavation  under  the  high  southward  slopes  due 
to  more  northern  elevation ;  that  Michigan  was  discharging  its  abundant 
waters  through  the  Illinois  or  the  Kankakee  channel  to  the  Mississippi; 
Erie,  with  probably  Huron,  through  the  Wabash,  to  the  Ohio ;  and  Superior, 
through  the  Fox  or  Wisconsin,  to  the  Mississippi.  The  waters  of  Ontario 
are  supposed  to  have  gone  eastward  to  the  valley  of  the  Mohawk,  but  for 
want  of  satisfactory  evidence  as  to  any  other  course. 

The  following  are  the  views  of  Chamberlin  and  Leverett,  with  regard  to  the  stages 
in  the  interval  between  the  time  of  maximum  extension  and  that  of  the  Kettle  moraine  : 
(1)  Partial  deglaciation,  and  the  formation  of  a  sheet  of  drift  perhaps  20'  in  thickness, 
with  occasional  layers  of  soil  interbedded  in  the  drift.  (2)  Interval  of  deglaciation  of 
great  length,  the  surface  of  old  drift  sheet  deeply  oxidized,  leached,  much  eroded,  with 
thick  widespread  soil  above.  (3)  Deposition  of  main  body  of  loess  and  associated  silts 
along  the  Mississippi,  Illinois,  Wabash,  and  Ohio  rivers,  and  between  the  Illinois  and 
Mississippi,  and  the  material  in  southern  Indiana  and  southwestern  Ohio  called  "White 
Clay."  (4)  Long  interval  of  deglaciation,  and  deep  erosion,  cutting  large  valleys  in  the 
loess.  (5)  Formation  of  a  thick  sheet  of  drift  terminated  by  the  Shelbyville  moraine,  75' 
to  100'  deep,  the  maximum  advance  of  the  ice  after  the  long  deglaciation  having  termi- 
nated at  or  near  the  line  of  this  moraine  ;  and,  following  the  deposition  of  the  Shelbyville 
moraine,  other  moraines  in  succession  at  short  intervals  up  to  the  Kettle  moraine  series. 
(6)  An  interval  during  which  ice-lobes  and  ice-currents  were  shifted.  (7)  Moraines  of 
the  Kettle  moraine  series  of  Illinois  and  Wisconsin.  In  remarks  on  these  stages,  it  is 
•stated  that  as  far  as  the  correlation  of  the  Kettle  moraine  has  been  made  out,  the  Shelby- 
ville series  of  moraines  is  represented  in  western  Ohio  by  only  a  single  moraine,  and  in 
eastern  Ohio  and  northwestern  Pennsylvania,  it  is  nowhere  in  view,  and  is  supposed  to  be 
•concealed  by  the  Kettle  moraine  series.  The  correlate  line  across  western  Indiana  of  the 
Kettle  moraine  is  difficult  to  make  out.  In  eastern  Ohio  the  outer  belt  from  the  Scioto 
River  to  southwestern  New  York  has  knobs  and  basins  like  the  Kettle  moraine  ;  and  the 
moraine  south  of  the  Finger  Lakes  (Cayuga,  Seneca,  and  others)  is  made  the  probable  con- 
tinuation of  the  Kettle  moraine  series.  The  overwash  from  the  Lake  Michigan  and  Erie 
moraines  over  Saginaw  moraine  in  northern  Indiana  seems  to  show  that  the  ice  had 
withdrawn  from  the  Saginaw  moraine  while  it  was  forming  the  series  west  of  Lake 
Erie.  With  regard  to  the  conclusions  of  Chamberlin  and  also  of  Leverett  here  and 
•elsewhere  cited,  they  say  that  their  observations  are  still  in  progress,  and  their  state- 
ments are  not  to  be  taken  as  final. 

Upham  names  as  follows  the  Iowa-Minnesota  moraines,  commencing  at  the  south : 
1,  the  Altamont ;  2,  the  Gary ;  3,  the  Antelope  ;  4,  the  Keister ;  5,  the  Elysian ;  6,  the 
Waconia ;  7,  the  Dovre ;  8,  the  Fergus  Falls ;  9,  the  Leaf  Hills ;  10,  the  Itasca ;  11,  the 
Mesabi ;  12,  the  Vermilion  (Final  Rep.  Geol.  Minn.,  vols.  i.,  ii.,  and  22d  Ann.  Rep.). 

Lateral  moraines  are  seldom  well  marked  over  any  part  of  glaciated 
North  America,  because  the  mountains,  with  rare  exceptions,  were  beneath 
the  ice-sheet;  and  there  were  no  true  valley  glaciers,  except  occasionally 


970  HISTORICAL   GEOLOGY. 

along  the  front.  But  in  some  large  submerged  valleys,  like  that  of  the 
Connecticut,  in  which  the  bottom  ice  had  a  movement  of  flow  in  the  direc- 
tion of  the  valley,  there  were  sometimes  obstructing  conditions  which  pro- 
duced a  forced  deposition  of  bowlders  and  till,  and  thus  made  an  accumulation 
somewhat  moraine-like,  which  might  be  called  an  obstruction  moraine. 

A  good  example  exists  along  the  west  side  of  the  south  end  of  the  Connecticut  valley, 
in  the  vicinity  of  New  Haven.  This  declivity  is  rather  abrupt,  and  has  a  nearly  north- 
and-south  direction,  while  the  course  of  the  valley  ice-stream,  as  described  on  page  956, 
was  S.  15°  W.  The  ice-stream,  in  meeting  the  obstructing  ridge  or  declivity,  dropped  along, 
it  a  large  amount  of  till  and  many  great  bowlders  of  trap  and  sandstone.  The  top  of  the 
ridge,  five  miles  from  the  Sound,  is  about  300'  above  the  lower  land  to  the  east,  and  400' 
above  the  sea  level.  One  great  bowlder  of  1200  tons,  and  several  others  of  large  size 
near  by,  were  a  little  too  low  in  the  ice  to  pass  the  top  of  the  ridge,  and  consequently 
became  stranded  against  its  slopes,  or  combed  out  by  its  summit  ledges.  Half  a  mile 
north  is  another  trap  bowlder  of  500  tons,  and  several  exceeding  100  tons  lie  to  the  south. 
A  mile  and  a  half  to  the  east,  but  separated  by  an  open  valley  300'  deep,  stands  the  West 
Rock  trap  ridge,  of  equal  height ;  and  on  this  ridge,  and  almost  in  an  east  and  west  line 
with  the  1200-ton  bowlder  iust  mentioned,  at  a  like  height,  there  is  a  1000-ton  bowlder, 
which  was  similarly  stranded.  For  a  distance  of  10  miles  from  Long  Island  Sound 
the  great  bowlders  are  common,  and  the  till  against  the  slopes  has  unusual  thickness. 
The  upper  part  of  the  glacier  above  the  level  of  the  ridges  kept  on  its  southeastward  course 
(S.  30°-40°  E.),  carrying  bowlders  of  gneiss  from  the  northwest.  But  some,  if  not  all, 
of  these  gneiss  bowlders,  while  on  their  way  over  the  valley,  dropped  down  so  as  to  come 
within  the  lower  or  valley  ice-movement ;  and  they  are  now,  as  a  consequence,  part  of 
the  obstruction  moraine  along  the  eastern  base  of  the  West  Rock  Ridge,  and  other  north- 
and-south  trap  ridges  of  the  valley. 

Among  the  formations  produced  by  the  melting,  besides  moraines  and 
deposits  of  till,  clay,  and  other  ordinary  materials,  there  were  glacial  accumu- 
lations of  loose  materials  called  drumlins,  and  eskers  or  Jcames,  —  formations 
that  were  much  less  common  in  connection  with  the  early  partial  retreat, 
than  with  the  final.  Kettle-holes,  also,  were  a  feature  of  many  moraines, 
from  the  Coteau  des  Prairies  to  Cape  Cod. 

Kettle-holes  are  bowl-shaped  depressions,  usually  30  to  50  feet  deep  and 
100  to  500  feet  in  larger  diameter.  Each  depression,  according  to  the  accepted 
explanation,  was  the  resting-place,  and  often  the  burial-place,  of  a  huge  mass 
of  ice  that  became  detached  during  the  melting ;  and  the  final  melting  away 
of  the  ice  left  a  hole  where  the  ice  lay.  The  great  Wisconsin  moraine  about 
Green  Bay  is  called  by  Chamberlin  the  "Kettle  Range,"  from  the  great 
numbers  of  its  kettle-holes.  Near  Wood's  Hole,  in  southeastern  Massachu- 
setts, opposite  Martha's  Vineyard,  1000  kettle-holes  occur,  according  to  B.  F. 
Koons,  in  a  distance  of  about  12  miles.  Kettle-holes  occur  sparingly  over 
Long  Island ;  but  it  is  possible,  since  there  is  clay  beneath  the  drift,  that 
the  weight  of  the  overlying  drift,  with  the  addition  of  the  resting  glacier  in 
some  cases,  forced  aside  the  clay,  flexing  its  layers  in  the  process,  and  thus 
made  the  bowl-like  depressions. 

Drumlins  are  hills  or  ridges  of  till,  30  to  200  feet  high,  made  ordinarily 
by  deposition  from  the  glacier,  or  in  the  course  of  its  dissolution ;  and 


CENOZOIC    TIME  —  QUATERNARY.  971 

eskers  or  frames  are  rougher  ridges  and  hills  of  rudely  stratified  coarse  and 
fine  gravel,  produced  by  the  discharged  waters.  Drumlins  occur  in  great 
numbers  over  New  England,  especially  in  Massachusetts  and  its  more  northern 
states,  and  also  in  New  York  and  the  states  west  to  Dakota.  Eighteen 
hundred  drumlins  have  been  observed  in  Massachusetts  alone,  and  thousands 
are  reported  from  Wisconsin  and  the  adjoining  states. 

Eskers  are  widely  distributed  over  Maine,  and  are  common  in  other  parts, 
of  New  England  and  in  most  regions  of  the  melting  ice. 

Drumlins  are  commonly  more  or  less  oblong,  smooth-featured  hills,  having  the  longer 
diameter  in  the  direction  of  the  movement  of  the  glacier.  In  allusion  to  their  form,  they 
were  called  "lenticular  hills"  by  E.  Hitchcock,  their  first  describer  (1842).  Such  hills 
may  be  shaped  by  fluvial  action  from  beds  of  till.  But  drumlins  are  generally  results  of 
local  deposition.  Their  height  indicates  a  source  elevated  above  the  general  level.  Such 
a  source  is  afforded  by  the  drift  in  the  lower  200  feet  or  more  of  the  ice.  They  were 
probably  formed,  therefore,  under  the  ice-sheet,  and  not  far  from  its  melting  margin.. 
To  gather  and  pile  up  the  drift  within  the  ice  would  require  the  descent  of  water  along 
crevasses,  the  water  acting  by  melting,  eroding,  and  transporting.  If  the  crevasse  had  a 
direction  toward  the  front,  the  slow  movement  of  the  ice  would  bring  forward  new  mate- 
rial for  the  enlargement  and  elongation  of  the  hill.  A  large  trench  is  sometimes  made 
about  a  dramlin  to  carry  off  the  copiously  descending  waters. 

Crevasses  are  often  due  to  obstructing  rocky  ledges  or  hills  below,  or  to  bends  in  a 
valley-like  depression ;  and  being  thus  local  in  origin,  the  same  spot  may  be  long  accu- 
mulating deposits. 

Drumlins  sometimes  have  a  nucleal  mass  of  stratified  gravel  and  sand  containing 
occasionally  intercalated  till;  and  those  of  Madison,  Wis.,  have  the  till  confined  to  an 
outer  shell,  20'  or  30'  thick.  Upham,  who  has  described  such  drumlins,  attributes  the 
nucleal  stratified  portion  to  moraine  materials  over  the  melting  margin  of  the  ice  carried 
down  by  the  superglacial  waters ;  and  the  till  to  the  final  wasting  of  the  glacier,  or  its 
removal  by  the  descending  waters.  They  sometimes  show  their  subglacial  origin  by 
being  crossed  by  small  valleys  or  trenches  of  erosion  (G.  H.  Barton). 

A  druinlin  of  nearly  circular  outline,  on  the  west  side  of  the  valley  at  New  Haven, 
Conn.,  height  115',  stands  on  the  summit  of  a  rocky  ridge,  its  base  being  nearly  200'  above 
the  sea  level.  The  valley  is  the  south  end  of  the  Connecticut  valley  near  where  it  passes 
into  the  trough  of  Long  Island  Sound.  The  lower  part  of  the  ice  lying  in  the  valley  was 
moving  S.  15°  W.  But,  on  reaching  the  trough  of  the  Sound,  it  was  forced  to  bend 
abruptly  around  to  S.  20°-35°  E.  in  order  to  take  the  course  of  the  general  glacier  move- 
ment along  the  Sound.  This  high  isolated  drumlin  and  lower  accumulations  along  the 
coast  westward  are  evidence  of  the  wrenching  and  crevassing  at  the  turning  spot.  This 
drumlin  has,  for  half  of  its  circuit,  a  deep  valley,  made  by  the  deluge  of  waters  that 
descended  the  crevasse. 

Eskers  or  Kames,  unlike  the  drumlins,  are  rudely  stratified  accumulations  of  gravel, 
sand,  and  waterworn  stones.  They  are  of  rough  fluvial  or  torrential  origin,  and  occur 
in  long  tortuous  ridges  (serpent-kames),  mounds,  and  hummocks.  They  have  the  general 
direction  of  the  drainage,  though  sometimes  not  according  with  the  present  course  of 
drainage.  They  occur  usually  over  the  lower  lands,  outside  of  the  steep  mountains 
where  the  slopes  are  not  large  ;  yet  they  are  sometimes  met  with  at  high  elevations. 
Indian  Ridge,  near  Andover,  Mass.,  was  the  first  of  them  described  (1842,  by  E.  Hitch- 
cock). Several  modes  of  origin  have  been  suggested.  Their  formation  has  generally 
taken  place  after  melting  had  made  great  progress  over  regions  favorable  to  torrential 
flows  ;  where  water,  coarse  gravel,  and  sand  were  freely  discharged  from  the  broken  and 


'972  HISTORICAL   GEOLOGY. 

melting  ice-sheet  and  sometimes  flowed  along  channels  among  the  ice-masses  or  in  its 
opened  chasms.  They  were  formed  also  by  the  gushing  streams  from  the  end  of  glaciers 
while  the  ice  was  rapidly  disappearing,  and  sometimes  beneath  the  ice.  They  often 
accompany  moraines  as  an  attendant  effect.  Stone  refers  those  of  Maine  chiefly  to 
•superglacial  streams ;  and  J.  B.  Woodworth,  those  of  southern  New  England  mainly  to 
subglacial  waters,  the  ice  giving  them  their  limits.  Deposition  seems  to  have  some- 
times taken  place  in  Maine  over  frozen  soil  and  lakes,  so  that  when  the  ice  of  the  lake 
melted  (as  in  the  case  of  the  Rangely  Lakes)  the  kame  over  it  dropped  to  the  bottom. 
Some  of  the  so-called  kames  are  ordinary  fluvial  deposits.  Kames  were  so  named 
in  Scotland.  The  EsTcers  of  Ireland  and  Osars  of  Sweden  are  of  like  nature. 

The  till  along  seacoasts  sometimes  contains  marine  shells  that  had  been  gathered  and 
transported  by  the  glacier.  Examples  occur  in  the  vicinity  of  Boston  Harbor,  especially 
to  the  southeast  of  it,  and  have  been  described  by  Upham  (1888),  and  by  W.  O.  Crosby 
and  Miss  Ballard,  who  enumerate  55  species  collected  chiefly  from  drumlins  (1894).  Simi- 
lar localities,  described  by  R.  Chalmers  (1893),  exist  on  the  coast  of  the  Bay  of  Fundy. 

The  till  over  Ohio  has  a  mean  depth,  according  to  measurements  in 
borings  made  over  53  counties,  collated  by  Orton,  exceeding  93  feet,  and 
four  borings  in  Butler  County,  in  the  southeast  corner  of  the  state,  gave 
116  feet  for  the  mean  depth.  The  deeper  places  were  along  valleys. 
Excluding  valley  deposits,  the  depth  is  probably  nearer  56  feet,  as  measured 
by  Claypole.  In  Indiana  and  Illinois,  the  mean  depth,  according  to  Clay- 
pole,  is  62  feet ;  for  Central  Minnesota,  according  to  Upham,  between  100 
and  200  feet.  Near  Darrtown,  Butler  County,  Ohio,  there  are  cedar  logs  in 
the  till,  which,  Wright  says,  point  to  short  times  of  advance  and  recession 
of  the  ice-front. 

The  Erie  days,  so  named  by  Logan  because  forming  extensive  deposits 
along  Lake  Erie,  are  one  of  the  results  of  deposition.  According  to  an 
analysis  by  T.  G.  Wormley,  the  clay  contains  3*40  per  cent  of  alkalies, 
which  indicates  a  mixture  of  clay  with  over  20  per  cent  of  ground  feldspar. 
They  overlie  the  till,  are  unstratified  for  the  most  part,  and  often  contain 
small  scattered  striated  bowlders.  The  deposit  was  probably  made  by  sub- 
glacial  streams  after  their  escape  from  the  ice,  and  by  discharged  waters 
during  the  general  melting.  Over  the  Erie  clays,  near  Cleveland,  Ohio, 
there  is  a  stratum  of  sand,  gravel,  and  clay,  and  between  the  two  occurs  a 
bed  of  vegetable  debris,  one  to  two  feet  thick,  which  Newberry  called  a  forest- 
bed.  It  contains  portions  of  tree  trunks  of  Conifers  and  other  vegetable 
materials.  It  may  belong  to  the  Champlain  period. 

In  the  Rocky  Mountain  region  of  British  America  and  over  the  Interior  Plateau  to 
the  west,  as  G.  M.  Dawson  states,  the  later  till  is  covered  by  a  deposit  called  by  him  the 
*'  White  silts,"  a  well-stratified  formation  which  is,  at  times,  in  terraces  100'  to  200'  high. 
Sometimes  it  passes  gradually  into  sand-beds.  It  is  supposed  by  him  to  have  been  formed 
in  the  valleys  of  those  high  regions  before  the  ice  had  fully  disappeared  from  them. 

The  obstruction  of  river  valleys  at  points  by  the  discharged  till  was  of 
common  occurrence  during  the  Final  Eetreat.  A  noted  case  is  that  of 
Niagara  River,  where  the  river  channel,  then  shallow,  was  thus  filled  and 
the  stream  forced  to  begin  again  the  work  of  excavation. 


CENOZOIC   TIME  —  QUATERNARY. 


973 


The  accompanying  birdseye  view  (Fig.  1551),  from  a  paper  by  Gilbert,, 
shows  the  river  between  Lake  Erie  to  the  south  and  the  land  below  the- 
Queenston  Heights  (Q  H).  To  the  right  is  seen  the  course  of  the  old  now 
drift-filled  channel,  first  recognized  by  Lyell.  The  work  of  excavation  is. 
still  going  on,  and  chiefly  at  Niagara  Falls. 

The  Mississippi  River  was  similarly  blocked  near  its  junction  with  the 
Minnesota  for  a  distance  of  about  10  miles,  as  described  by  N.  H.  Winchell. 
In  the  new  valley,  since  made  by  the  Mississippi,  St.  Anthony's  Falls  occur. 
The  river  is  still  working  at  the  removal  of  the  falls  so  as  to  make  the 
cut  complete. 

1551. 


Birdseye  view  of  the  Niagara  Gorge.     W,  Whirlpool ;  Q,  Queenston ;  Q  H,  Queenston  Heights ;  O  (Jh,  ol<Ji 

channel.    From  Gilbert. 

Rock  River,  in  northwestern  Illinois,  is  stated  by  Chamberlin  and  Lever- 
ett  to  have  been  a  tributary  to  the  Illinois  before  the  deposition  of  the 
Kettle  moraine.  But,  through  the  drift-deposits  then  made,  it  was  filled  up. 
for  part  of  its  course  and  thus  was  set  to  work  making  its  present  south- 
westward  channel  to  the  Mississippi. 

During  this  time  of  melting,  fluvial  work  was  going  on  over  all  parts  of 
the  continent  —  quiet  waters  and  those  of  prolonged  floods  alternating,  where 
within  the  influence  of  the  glaciers.  The  height  of  much  of  the  land  may 
still  have  favored  the  work  of  erosion  along  many  valleys. 

The  Mississippi  was  the  greater  Mississippi  through  the  larger  part  of 
the  time  ;  for  there  is  yet  no  proof  that  before  the  ice  left  the  United  States 
it  had  lost  its  Winnipeg  and  Saskatchewan  source.  The  valley  received 
new  deposits  of  loess  and  silt  along  some  still-water  portions,  part  of  it  over 
the  earlier  Lafayette  formation,  and  silt  and  coarser  beds  elsewhere.  The 
rivers  of  the  Atlantic  border  south  of  New  York  were  adding  to  the  deposi- 
tions in  their  valleys  and  along  the  seashore.  But  since  snows  were  less- 


974  HISTORICAL    GEOLOGY. 

-common  in  the  Appalachians  than  during  the  First  Retreat,  water  was  less 
abundant,  and  the  deposits,  therefore,  were  generally  much  like  those  of  more 
recent  time. 

Deposits  on  the  Atlantic  border,  partly  marine  and  estuarine,  and  those 
of  similar  character  elsewhere,  have  been  named  the  Columbian  formation. 
This  formation  is  described  by  McGee  (1888  and  later)  as  occurring  over  the 
coastal  plain  of  the  Atlantic  slope,  and  ranging  in  height  from  over  100  feet 
in  the  south  to  400  or  more  in  the  north.  It  consists  of  a  series  of  sub- 
estuarine  and  submarine  deltas  and  associated  littoral  deposits.  The  pre- 
dominant and  most  significant  phenomena  are  widespread  stratified  deposits 
and  associated  terraces,  newer  than  the  Lafayette  formation  of  the  same 
coastal  region.  Part  of  the  deposits  made  during  the  earlier  retreat  also  are 
described  as  Columbian.  The  formation,  according  to  McGee,  is  in  part  of 
submarine  origin. 

Another  result  of  the  melting  and  depositions  during  the  long  retreat  was 
the  making  of  innumerable  lakes,  especially  over  the  more  level  portions  of 
the  glaciated  region.  There  were  probably  thousands  where  there  are  now 
scores  —  like  the  Tundra  regions  of  similar  origin,  in  Russia.  The  gradual 
action  of  waters  during  their  flood  seasons  have  converted  many  lines  into 
drainage  channels,  while  numerous  others  have  gradually  become  shallowed 
by  depositions  of  earth  and  organic  materials  and  passed  to  the  conditions 
of  swamps  ;  and  the  swamps  have  ever  since  been  drying  up. 

Topographical  results  of  abrasion  by  the  ice  and  ice-made  streams.  —  The 
minor  effects  of  abrasion  by  glaciers  are  scratches,  groovings,  polishing  of 
surfaces  over  the  harder  rocks;  making  deep  channels  in  the  softer,  such 
as  limestone  and  many  sandstones ;  producing  forms  over  the  surface  like 
the  moldings  in  architecture,  but  yards  in  depth  and  width,  where  the 
architect  puts  inches ;  carving  out  roches  moutonnees,  an  example  of  which, 
from  the  region  of  the  Holy  Cross  in  Colorado,  is  represented  on  page  250 ; 
but  not  boring  out  pot-holes,  which  requires  a  stationary  tool. 

The  larger  effects  of  direct  abrasion  on  the  softer  rocks  are  long  and 
wide  trenches,  one  or  more  hundreds  of  feet  deep ;  shallow  lake-basins, 
like  that  of  Mono  Lake  in  Nevada,  which,  according  to  Russell,  was  excavated 
out  of  limestone  to  a  depth  of  51  feet  below  the  existing  rim,  its  bottom  and 
sides  being  limestone ;  river  channels ;  ridges  elongated  in  the  direction 
of  the  movement  of  the  ice ;  steep  fronts  on  the  struck  or  stoss  side  of 
hills  —  the  side  facing  the  ice-stream ;  and  long-drawn-out  ridges  with 
gentle  slopes  on  the  opposite  side.  Another  case  is  that  of  soft  rocks  saved 
from  removal  by  being  under  the  lee  of  a  ridge  of  harder  rocks,  the  harder 
ridge  making  a  great  cavity  or  notch  in  the  ice,  —  as  near  New  Haven,  Conn., 
where  a  ridge  of  weak  sandstone  (Sachem  Ridge,  on  the  map,  page  993), 
a  mile  long  and  100  to  165  feet  high,  was  left  under  the  lee  of  a  trap  ridge 
(Mill  Rock),  just  as  a  tool  with  a  notch  in  its  cutting  edge  leaves  a  raised 
line  on  the  surface  of  a  board.  The  tearing  and  displacing  work  of 
frosts  and  freezing  was  also  going  on  over  all  frosty  regions,  even  those 


CENOZOIC    TIME  —  QUATERNARY.  975 

not  glaciated.  Deep  lake  basins  in  the  harder  rocks  are  not  regarded  as 
among  the  possible  results  of  glacier  excavation,  their  existence  in  glaciated 
regions  being  generally  due  to  the  damming  of  channels  by  the  glacial 
deposits  and  sometimes  to  changes  in  level. 

Thus  a  glaciated  country  bears  everywhere  the  marks  of  the  ice.  The 
more  delicate  marks — the  scratches  or  groovings — would  be  now  universally 
visible  over  the  exposed  rocks,  were  it  not  for  their  removal  by  weathering. 
On  the  harder  rocks  they  may  generally  be  found  by  removing  the  soil. 

The  effects  of  abrasion  and  degradation  are  apparent  also  in  the  grander 
work  of  shaping  mountains  and  excavating  deep  valleys ;  but  in  the  pro- 
duction of  these  results,  the  ice  was  aided  to  a  very  large  extent  by 
the  subglacial  streams.  Moreover,  the  degradation  and  excavation  were 
•carried  on  as  effectually,  or  more  so,  by  the  later  floods  from  the  melting 
ice.  The  fiords  are  attributed  to  the  ice ;  but  the  waters  from  the  melted  ice 
were  the  main  eroding  agent,  while  the  ice  worked  chiefly  by  lateral  abrasion. 

FOREIGN. 

In  Europe  the  region  of  the  Scandinavian  Mountains  was  the  great 
center  of  the  accumulation  and  distribution  of  ice  and  bowlders.  There 
were  also  some  local  centers :  as  in  the  Scotch  Highlands ;  in  the  Alps,  Urals, 
Caucasus,  and  Pyrenees  ;  in  the  mountains  of  Auvergne,  Lyonnais,  and  Beau- 
jolais,  in  France.  At  the  time  of  maximum  glaciation  the  ice  was  continuous 
from  Scandinavia  westward  over  the  British  Isles,  eastward  to  the  Urals,  and 
southward  almost  to  the  parallel  of  50°.  The  ice  spread  over  nearly  55°  of 
longitude,  which  is  10°  more  than  was  true  in  North  America  between  the 
•coast  of  Labrador  and  the  Coteau  des  Prairies;  but  the  degrees  are  much 
shorter,  as  the  southern  limit  of  the  area  lay  10°  to  13°  farther  north  than 
the  North  American.  This  difference  in  southern  limits  corresponds  with 
the  existing  difference  in  the  positions  of  isotherms  on  the  two  continents. 
The  glacier  did  not  cover  England  south  of  the  Thames,  nor  any  part  of  France. 
Brussels  and  Dresden  were  near  its  limit.  The  accompanying  map  (Fig. 
1552),  by  J.  Geikie  (from  his  paper  on  The  Glacial  Succession  in  Europe, 
Roy.  Soc.  Edinb.,  1892)  shows,  by  the  paler  shading,  the  supposed  limits 
of  the  ice  during  the  time  of  maximum  glaciation,  and  by  the  darker  color, 
those  during  the  epoch  of  the  later  Baltic  glacier. 

The  glacial  drift  crossed  the  Baltic  from  Scandinavia  eastward  and 
southeastward  over  north  Russia,  the  Baltic  Provinces,  and  Moscow,  reach- 
ing nearly  as  far  south  as  Kieff ;  and  southward  over  Denmark,  part  of  Ger- 
many, and  Poland.  It  spread  southwestward  over  the  Faroe  and  Shetland 
Islands  and  to  the  coast  of  Norfolk,  in  England.  The  distance  of  travel 
varied  from  five  miles,  or  less,  to  500  or  600.  There  is  evidence  also  of  trans- 
portation toward  the  Polar  regions. 

In  Great  Britain,  the  movements  were  mainly  in  the  direction  of  the 
slopes  of  the  mountains  and  their  valleys,  the  drift  radiating  from  different 


976 


HISTORICAL   GEOLOGY. 


centers,  as  the  Highlands  and  Southern  Uplands  of  Scotland,  the  mountains- 
of  the  Lake  country  in  northern  England,  and  the  Snowdonian  heights  in 
North  Wales ;  but  only  England  received  bowlders  from  Scandinavia. 


1552. 


Showing  distribution  of  ice'during  Epoch  of  Maxim 
Glaciation,  and  chief  areis  occupied  by.snow-flelds, 
local  ice-sheetfi/and  glaciers  during 
Fourth.Glacial  Epoc 


The  height  of  northern  Europe,  if  it  was  such  as  the  fiords  indicate,. 
was  sufficient  to  make  dry  land  of  the  German  Ocean  (it  being  generally 
under  500  feet  in  depth,  and  800-1200  feet  along  the  Norway  coast)  and 
join  Great  Britain  and  Ireland  to  the  continent,  besides  giving  these  islands 
widely  extended  borders  on  the  Atlantic  side.  The  depths  of  some  Norwe- 
gian fiords  vary  from  2000  and  less  to  4020  feet. 

The  drift  phenomena  are  exhibited  on  a  grand  scale  about  the  Alps,, 
especially  along  the  valleys  of  the  Ehone  and  Ehine.  Lines  of  stones  and 
gravel,  and  even  great  bowlders,  have  been  traced  (first  by  Professor  Guyot) 
from  the  Alpine  summits  about  Mount  Blanc,  by  the  valleys  of  the  Trient 
and  Rhone,  to  the  plains  of  Switzerland,  and  thence  over  the  sites  of 
Geneva  and  Neufchatel  to  the  Jura  Mountains  on  the  borders  of  France ; 
and  the  declivity  of  this  range,  facing  the  Alps,  is  covered  with  the 
bowlders ;  one  of  them,  the  Pierre-a-bot,  —  a  mass  of  granite  (or  more 
properly  protogine),  —  is  62  feet  long  by  48  broad,  and  contains  about 
40,000  cubic  feet,  equivalent  to  a  weight  of  3000  tons. 

Moreover,  the  valleys  of  the  Alps  have  their  sides  nearly  horizontally 
grooved  or  planed,  to  a  height  of  10,000  feet  above  the  sea,  or  more  than 


CENOZOIC    TIME  —  QUATERNARY.  977 

2000  feet  above  the  present  upper  limit  of  the  glaciers,  or  the  level  of  any 
existing  adequate  abrading  agency.  The  bowlders  and  scratches  have  been 
traced  beyond  Geneva,  even  to  Lyons,  and  to  Vienne,  in  Dauphine. 

A  second  epoch  of  glaciation  is  generally  supposed  in  Europe  to  have  followed  a 
period  of  depression  like  that  of  the  Champlain  period,  as  mentioned  beyond.  J.  Geikie 
makes  the  number  of  Glacial  epochs  in  Europe  five  ;  but  four  counting  from  the  epoch  of 
maximum  glaciation.  In  his  Ice  Age,  of  1894,  he  recognizes  in  Great  Britain  six  epochs, 
two  of  them  after  the  Great  Baltic  glacier,  or  4th.  The  first  epoch  in  each  case  preceded 
the  deposition  of  the  Cromer  Forest  bed  (page  927). 

But  the  lofty  mountains  of  Scandinavia  —  now  in  some  peaks  over  8000'  in  height  and 
glacier- covered,  and  then  probably  11,000'  or  12,000'  —  were  not  far  distant,  so  that  the 
glacial  deposits  of  Great  Britain  might  well  bear  evidence  of  the  fluctuating  conditions 
in  the  ice  arising  from  modifications  of  climate  and  other  causes.  Oscillations  in  the 
deposits  from  till  to  stratified  gravels  and  the  reverse  may  have  required  no  great  length 
of  time,  and  need  no  other  cause.  As  Krapotkin,  of  Russia,  says  (1894),  "The  oscilla- 
tions of  the  fringe  of  a  vast  ice-sheet  may  account  for  the  formation  of  the  layers  which 
are  described  as  interglacial.  The  considerable  changes  which  must  occur  in  the  direc- 
tions of  flow  of  the  ice-sheet  may  account  for  the  crossing  of  striae  and  erratics,  as  well  as 
for  the  occurrence  of  interglacial  beds."  The  deposits  referred  to  as  marking  the  intervals 
are  not  such  as  would  necessarily  have  demanded,  in  each  case,  a  long  period  of  tune. 

It  is  a  remarkable  fact  that  no  ice-mass  covered  the  low  lands  of  northern 
Siberia  any  more  than  those  of  Alaska.  But  recent  accounts  report  that 
"  the  High  Plateau  of  Asia,  which  stretches  northeastward  from  the  Hima- 
layas as  an  immense  triangle  having  its  summit  at  Bering  Strait,  bear 
unmistakable  traces,  where  studied  in  the  region  of  the  gold  mines,  of  having 
been  covered  with  thick  sheets  of  ice.  This  is  true  of  the  border  mountains 
of  the  High  Plateau,  the  Himalayas,  the  Tian-Shan,  the  Altai,  the  Sayan, 
the  Great  Khingan,  and  others.  With  these  few  data,  the  only  plaus- 
ible hypothesis  is  that  all  of  the  High  Plateau  above  2000  feet  to  the 
north,  above  3000  feet  to  the  east  of  Lake  Baikal,  above  5000  feet  in  the 
middle  portions,  and  still  higher  farther  south,  were  covered  with  ice" 
(Krapotkin,  1894). 

Over  the  southward  slopes  of  the  Himalayas,  evidences  of  glacier  action 
have  been  observed  down  to  a  level,  2000  feet  above  sea  level  in  the  Kangra 
Valley ;  to  4700  feet  on  the  southern  slopes  of  the  Dhaoladhar ;  and  to  5000 
to  7000  feet  in  many  valleys  of  Sikkini  and  eastern  Nepaul.  They  occur 
also  on  Mount  Antilibanus  in  Syria,  in  latitude  34°  N.,  on  the  Atlas  Moun- 
tains in  northern  Africa,  and  on  Mount  Kenya,  a  peak  about  18,500  feet 
high,  not  far  from  Kilima-Njaro,  in  British  East  Africa. 

In  South  America,  indications  of  a  great  ice-mass  are  met  with,  from 
Fuegia,  as  far  toward  the  equator  as  the  parallel  of  37°  S.,  and  especially,  as 
Agassiz  has  shown,  in  the  great  valley  between  the  main  chain  of  the  Andes 
and  the  Coast  Mountains,  to  the  latitude  of  Concepcion.  Besides,  glaciers 
had  great  extent  about  some  of  the  higher  summits  along  the  Andes,  and  one 
near  the  equator.  A.  E.  Douglass,  of  the  Harvard  College  Observatory  at 
Arequipa,  has  reported  the  existence  of  glacial  phenomena  of  great  extent, 
DANA'S  MANUAL  —  62 


978  HISTORICAL   GEOLOGY. 

including  vast  moraines,  on  the  slopes  of  Charchani  in  southern  Peru.  Gla- 
ciers existed  in  the  Cordillera  of  Columbia  about  the  peak  of  Cocui,  9,000  feet 
high,  and  in  the  Sierra  Nevada  de  Santa  Marta,  15,400  feet  in  height.  In 
this  region  the  decrease  in  temperature  with  altitude  is  now  about  1°  F.  in 
330  feet. 

In  New  Zealand,  glaciers  descended  along  the  so-called  Alps  on  the  west 
side  of  the  southern  island,  probably  to  the  sea  level.  They  were  properly 
local  glaciers.  Captain  Hutton  states  that  in  New  Zealand  the  mountains 
were  3000  to  4000  feet  higher  than  now.  There  were  glaciers  also  in  the 
Australian  Alps  about  Mount  Kosciusko  in  southeastern  Australia,  as  re- 
pprted  by  Von  Lendenfeld  in  1885,  and  in  1893  by  E.  Helms,  and  in 
western  Tasmania. 


CAUSE  OF  THE  CLIMATE  OF  THE  GLACIAL  PERIOD. 

A.  The  cold  climate.  —  1.  The  elevation  of  the  land  over  the  globe,  and 
especially  in  the  higher  latitudes,  if  a  fact,  as  appears  to  be  proved,  is  a 
sufficient  reason  for  a  large  increase  of  cold,  and  thereby  of  frigid  winds ; 
and  alone  it  goes  far  toward  explaining  the  extension  of  a  polar  climate  over 
the  lower  lands  to  latitudes  where  now  the  July  temperature  is  65°  to  70°  F. 

2.  This  elevation  would  have  made  dry  land,  or  a  very  shallow  belt  of 
water,  across  the  North  Atlantic  from  Scandinavia  to  Greenland  and  thus 
the  Arctic  regions  would  have  been  deprived  of  the  large  supply  of  heat  they 
now  derive  from  the  Gulf  Stream. 

3.  The  confinement  of  the  circuit  of  the  Gulf  Stream  to  the  middle  por- 
tions of  the  North  Atlantic  would  concentrate  thus  its  heat,  make  a  much 
warmer  ocean,  and  produce  abundant  precipitation. 

4.  With  abundant  vapors  for  precipitation  thus  produced,  and  the  conti- 
nents largely  under  a  frigid  climate,  the  snows  which  would  have  descended 
abundantly,  would  have  been  distributed  over  different  regions  with  some 
reference  proportionally  to  the  ratio  of  precipitation ;  and  this  ratio  would 
have  been  the  modern  ratio,  modified  by  the  topographic  and  oceanic  con- 
ditions then  existing. 

The  cold  of  the  Glacial  period  has  been  attributed  to  the  loss  of  the  Gulf  Stream  by 
the  Atlantic  through  the  deep  submergence  of  the  Isthmus  of  Panama.  But  such  a  sub- 
mergence is  not  sustained  by  evidence  in  the  region.  Moreover,  there  is  proof  that  the 
Gulf  Stream  had  the  same  effect  on  European  climate  in  the  Glacial  period  as  now,  in  the 
fact  that  the  relation  of  the  isotherms  of  the  two  continents  was  unchanged. 

Croll's  theory,  which  makes  the  occurrence  of  a  cold  period  dependent  on  the  eccen- 
tricity of  the  earth's  orbit,  is  explained  on  page  254.  It  is  objected  to  by  American  geolo- 
gists on  the  ground  that  the  Glacial  period  closed,  according  to  American  geological  facts, 
not  more  than  10,000,  or  at  the  most  15,000,  years  ago  (page  255),  instead  of  150,000, 
or  at  the  least  80,000,  as  the  eccentricity  hypothesis  requires.  According  to  this  theory, 
the  cold  epochs  of  the  northern  and  southern  hemispheres  occurred  11,500  years  apart, 
or  half  the  length  of  the  precession  cycle.  J.  Geikie,  who  recognizes  six  epochs  of  glacia- 
tion  during  the  Quaternary,  adopts  the  theory  mentioned,  and  refers  the  times  of  the  six 


CENOZOIC   TIME  —  QUATERNARY.  979 

epochs  to  as  many  precession  cycles,  during  one  period  of  maximum  eccentricity,  thus 
putting  several  thousand  years  between  the  till  deposits  of  successive  epochs  in  the  north- 
ern and  also  in  the  southern  hemisphere.  There  is  no  evidence  yet  reported  that  the 
Glacial  periods  of  the  two  hemispheres  were  not  essentially  simultaneous  in  their  epochs. 
For  a  full  appreciation  of  the  views  of  Geikie,  reference  should  be  made  to  the  recent 
edition  of  his  Ice  Age  (1894),  in  which  the  arguments  bearing  on  the  question  and  on  the 
views  of  others  are  fully  presented.  Moreover,  he  gives  a  later  map  of  the  Baltic  glacier 
than  that  he  published  in  1892. 

The  merits  of  Croll's  theory  have  been  discussed  mathematically  and  physically  by 
G.  F.  Becker  (Am.  Jour.  Sc.,  August,  1894),  with  adverse  conclusions,  as  follows :  — 

"  The  summer  of  the  eccentric  period  in  the  hemisphere  of  rigorous  climate  will  be  the 
hottest  possible,  nearly  20°  F.  hotter,  it  would  seem,  than  that  of  the  present  time  in  tem- 
perate latitudes.  The  evaporation  would  of  course  be  immense.  The  heat  gradient  toward 
the  pole  is  also  considerably  greater  than  it  now  is,  or  than  it  would  be  at  the  time  of  zero 
eccentricity.  Hence  the  summer  would  be  wet  as  well  as  hot.  It  seems  to  me,  then,  that 
the  period  of  greatest  eccentricity  would  be  most  unfavorable  to  glaciation,  the  snowfall 
being  the  smallest,  and  the  summer  rainfall  the  largest  which  can  occur  with  the  present 
obliquity.  It  seems  much  less  favorable  than  the  period  of  zero  eccentricity  when  the 
winter  cold  is  great  enough  to  preclude  much  rain  in  the  higher  portion  of  the  Temperate 
Zone,  while  the  temperature  in  the  tropics  is  great  enough  to  produce  active  evaporation. 
It  would  be  manifestly  absurd  to  suppose  equality  of  seasons  sufficient  to  produce  an  ice 
age  ;  but  I  am  forced  to  the  conclusion  that,  so  far  as  eccentricity  is  concerned  in  the 
matter  at  all,  the  smaller  the  eccentricity  the  more  favorable  are  the  conditions  for  glacia- 
tion." Considering  the  influence  of  the  variation  in  the  obliquity  of  the  ecliptic,  he  states, 
as  a  further  result  of  his  investigation,  "  that  the  combination  of  low  eccentricity  and  high 
obliquity  will  promote  the  accumulation  of  glacial  ice  in  high  latitudes  more  than  any 
other  set  of  circumstances  pertaining^  to  the  earth's  orbit.  It  seems  to  me  that  the  Glacial 
period  may  be  due  to  these  conditions  in  combination  with  a  favorable  disposition  of  land 
and  water.  .  .  .  All  the  indications  seem  to  point  to  the  conclusion  that  within  30,000  or 
40,000  years  conditions  have  occurred,  and  have  persisted  for  a  considerable  number  of 
thousand  years,  which  would  have  favored  glaciation  on  the  theory  of  this  paper." 

With  reference  to  the  return  of  the  warmer  climate  which  determined  the  departure  of 
the  ice,  the  theory  suggests  that  when  the  period  of  combined  low  eccentricity  and  high 
obliquity  of  the  apparent  ecliptic  was  passed,  the  area  of  evaporation  during  the  summer  of 
the  glaciated  hemisphere  must  have  increased,  and,  at  the  same  time,  the  temperature 
gradient  toward  the  pole  must  have  become  steeper.  Both  causes  would  have  led  to 
relatively  heavy,  warm  summer  rains  in  high  temperate  latitudes.  Such  rains  would 
rapidly  melt  the  ice-fields,  making  flooded  streams. 

The  amount  to  which  the  mean  temperature  of  the  globe  was  lowered 
to  bring  on  the  conditions  of  the  Glacial  period  was  probably  small.  The 
existing  mean  temperature  has  been  thought  by  some  to  be  sufficiently  low 
for  the  result,  provided  the  summers  were  cool,  and  excessively  wet  through 
an  increase  of  precipitation.  This  view  is  presented  by  J.  D.  Whitney,  in 
his  Climatic  Changes  of  Later  Geological  Time  (1882).  But  it  appears  to  be 
more  difficult  to  find  a  cause  for  such  excessive  precipitation  than  for  greater 
cold.  E.  Bruckner,  in  a  recent  discussion  of  the  subject,  concludes  that  a 
change  in  mean  temperature  of  8°  F.  to  10°  F.  would  be  sufficient.  The 
lowering  of  the  snow-line  in  Europe  required  would  be  not  over  3000  to  4000 
feet.  (Penck's  Geogr.  Abhandl,  1890.) 


980  HISTORICAL   GEOLOGY. 

B.  The  amelioration  of  the  cold,  and  the  retreat  of  the  ice-sheet.  —  Setting 
aside  Croll's  theory,  for  the  reasons  already  stated,  the  disappearance  of  the 
cold  and  wet  climate  that  was  the  occasion  of  the  ice  period  is  naturally 
attributed  to  a  reversal  of  the  conditions  that  produced  it  —  that  is,  to  a 
subsidence  of  the  land  over  the  higher  latitudes,  and  a  deepening  again  of 
the  sea  over  the  submarine  plateau  between  Scandinavia  and  Greenland, 
thereby  restoring  the  Gulf  Stream  to  its  circuit  in  the  Arctic  regions. 

But  there  appears  to  be  good  evidence  that  the  melting  had  made 
great  progress  before  there  had  been  much  subsidence  of  glacial  regions. 
The  facts  stated  on  page  969  bear  strongly  in  this  direction  ;  for  they  show 
that,  however  great  the  loss  from  melting  and  subsidence  may  have  been, 
the  southward  slope  of  the  ice-surface  continued,  and  the  Mississippi  drained 
a  large  part  of  British  America,  even  when  the  ice  was  making  its  last 
moraine  on  the  northern  borders  of  Minnesota. 

These  facts  from  the  Continental  Interior  are  sustained  by  others  from 
the  eastern  border.  It  has  been  shown  by  N.  L.  Britton  (1872),  that  the 
Pine  Barren  flora  of  the  New  Jersey  coast  region  formerly  occupied  Staten 
Island  and  Long  Island ;  and  others  have  added  to  the  range  of  its  distribu- 
tion the  southern  shores  of  Rhode  Island  and  Massachusetts,  with  the 
adjoining  islands.  A.  Hollick  has  reviewed  the  facts  (1893)  and  referred  the 
northward  distribution  of  this  southern  flora  to  the  period  of  Glacial 
emergence,  which  made  New  Jersey,  Staten  Island,  Long  Island,  with  the 
islands  east  of  it  and  southern  New  England,  continuous  dry  land. 

The  migration  northward  of  the  Pine  Barren  flora  must  have  been  during 
the  later  part  of  the  time  of  high  latitude  elevation.  The  flora  was  first 
driven  south  by  the  ice,  and  long  kept  there.  But  finally,  after  the  ice  had 
retreated  from  New  Jersey  it  was  again  restored;  and  when  the  retreat 
had  made  so  great  progress  that  the  climate  of  southern  New  England  was 
right  for  the  flora,  it  completed  its  northward  migration.  It  is  thus  proved 
that  southern  New  England  had  a  climate  warmer  than  now,  long  before 
the  alleged  subsidence  had  completed  its  work  in  southern  New  England. 

These  facts  do  not  prove,  however,  that  no  subsidence  had  taken  place 
in  higher  latitudes.  That  of  the  submarine  plateau  between  Europe  and 
Greenland  may  have  been  so  far  completed  as  to  have  caused  a  great  modi- 
fication in  climate.  Each  stage  in  the  retreat  was  a  contraction  of  the  area 
of  perpetual  frost,  and  a  widening  of  the  range  of  tropical  winds,  ensuring 
further  encroachment.  In  view  of  all  the  facts,  it  is  probable  that  before 
the  subsidence  had  made  large  progress,  the  ice-sheet  had  retreated  to  Cana- 
dian territory,  excepting  the  portions  left  about  the  higher  mountains  of 
eastern  and  western  America. 

It  seems  also  to  be  true  that  the  conclusion  of  Becker,  deduced  from  his 
discussion  of  the  question  of  Glacial  climate,  on  page  979,  suggests  the 
right  explanation  of  the  initiation  of  the  warmer  climate  and  retreat. 


CENOZOIC  TIME  —  QUATERNARY.  981 

2.  CHAMPLAIN  PERIOD. 
AMERICAN. 

The  Champlain  period  is  so  named  from  the  occurrence  of  beds  of  the 
period  on  the  borders  of  Lake  Champlain. 

The  term  Champlain  was  first  used  by  C.  H.  Hitchcock,  in  the  Report  on  the  Geology 
of  Vermont  (1861),  for  the  marine  beds  of  the  period  occurring  along  the  lake,  and  for 
similar  beds  in  the  St.  Lawrence  valley,  as  a  substitute  for  the  term,  "Laurentian 
deposits,"  applied  to  the  latter  by  Desor.  The  author,  in  a  paper,  in  1856,  adopted  the 
latter  name ;  but  as  Laurentian  was  earlier  given  by  Logan  to  a  subdivision  of  the 
Archaean,  Champlain  was  substituted  in  the  first  edition  of  this  work  (1863). 

The  prominent  events  of  the  period  are :  (1)  the  completion  of  the  sub- 
sidence begun  in  the  closing  part  of  the  Glacial  period  ;  (2)  the  subsidence 
over  large  areas,  greatest  to  the  north ;  (3)  the  disappearance  of  the  ice  that 
remained  on  the  mountains  and  elsewhere  within  the  borders  of  the  United 
States,  and  finally  from  the  Canadian  ice-plateau,  completing  the  deglacia- 
tion  of  the  continent;  (4)  a  change  of  climate  to  one  even  warmer  than 
that  of  Kecent  time ;  (5)  the  conversion  of  many  of  the  southward  flowing 
streams,  that  were  eroding  streams  in  the  Glacial  period,  into  feebly  mov- 
ing and  feebly  working  streams,  and  the  making  of  lakes ;  (6)  the  rapid 
growth  of  vegetation,  covering  hills,  mountains,  and  prairie  regions  with  the 
greatest  of  forests.  A  moister  climate  than  the  present  is  rendered  probable 
by  the  greatly  increased  surface  of  fresh  waters  in  lakes  and  rivers  over  the 
continent,  as  well  as  by  the  greater  warmth  of  the  climate. 

The  Champlain  has  been  sometimes  designated  the  Pluvial  period,  to  mark 
its  contrast  with  the  Glacial  period. 

THE   SUBSIDENCE. 

1.  Kind  of  evidence.  —  Evidence  of  the  subsidence  is  found  on  the  borders 
of  the  continent  in  elevated  shore-lines  of  the  Champlain  period,  as  beaches, 
shell-beds,  seashore  flats,  rock  plantations  or  terraces ;  and  over  the  interior 
of  the  continent  in  the  existence  of  lake-basins  that  were  occupied  by  Cham- 
plain  lakes,  some  of  them  exceeding  in  size  any  modern  lake. 

2.  Amount  over  the  eastern  Continental  border.  —  The  subsidence  increased 
in  amount  over  eastern  America  from  the  south,  northward,  and  also  from 
the  seashore,  landward.     The  difference  between  the  level  of  the  Champlain 
period  and  the  present  as  indicated  by  shore-lines,  terraces,  shell-beds,  and 
other  evidence  is  about  as  follows  at  the  places  mentioned  :  on  the  southern 
shores  of  New  England,  near  New  Haven,  20  feet ;  shell-beds  in  deposits  at 
Sancati  Head,  on  Nantucket,  80  feet ;  on  the  coast  of  Maine,  as  proved  by 
fossils,  150  to  300  feet ;  the  upper  benches  at  Mount  Desert,  Me.,  270  to  300 
feet  (Shaler). 

Along  the  north  and  south  valley  of  the  Connecticut,  terraces  increase  in 


982 


HISTORICAL   GEOLOGY. 


1553. 


height  northward,  to  260  feet  at  a  distance  of  200  miles  from  Long  Island 
Sound. 

Again,  at  the  mouth  of  Hudson  River,  according  to  F.  J.  H.  Merrill,  there 
is  evidence  of  a  Champlain  subsidence  of  70  feet ;  35  miles  up  the  river,  at 
Croton  Landing,  of  100  feet ;  50  miles  up,  of  180  feet ;  140  miles  up,  about 
Albany,  of  335  feet.  Farther  north  the  divide  between  the  Albany  plain 
and  that  of  the  Champlain  region,  was  evidently  covered  for  awhile  by  fresh 
water  as  stated  by  S.  P.  Baldwin ;  and  hence  the  rise  in  level  along  the 
Hudson  may  be  regarded  as  continued  along  Lake  Champlain.  A  reduced 

copy  of  a  map  of  Lake  Champlain  of  the 
Champlain  period  is  here  inserted  from 
a  paper  on  the  terraces  of  the  lake  by 
Baldwin  (1894).  On  the  southern  part 
of  the  lake,  at  Benson  Landing,  terraces 
extend  to  370  feet ;  at  Orwell,  410  feet ; 
at  Charlotte,  Vt.,  near  the  middle  of  the 
lake,  415  and  450  feet,  and  they  contain 
marine  shells;  at  St.  Albans,  near  its 
north  end,  500  feet.  Marine  shells  occur 
in  the  terraces  of  the  Vermont  side  to 
Addison,  or  through  the  northern  two 
thirds  of  the  lake,  and  at  Plattsburgh  on 
the  west  side. 

On  the  St.  Lawrence,  near  Montreal, 
30  miles  distant  in  a  nearly  north  direc- 
tion from  Lake  Champlain,  shell-beds 
occur  at  520  feet;  and  up  the  St.  Law- 
rence, according  to  Daw  son,  nearly  to 
Lake  Ontario,  west  of  Lake  Champlain, 
at  600  feet.  The  increase  in  the  height 
of  the  terraces  northward,  as  well  as  land- 
ward, is  here  apparent. 

But  these  heights  of  beaches  and  ter- 
races represent  but  a  small  part  of  the 
actual  change  of  level.  For  the  land  in 
the  preceding  period  stood  higher  than 
now.  Adding  to  the  above  the  minimum 
estimate  of  that  elevation,  the  actual 
amount  of  subsidence  for  southern  New 
England  is  160  to  170  feet ;  for  the  coast 
of  Maine,  1000  feet  or  more ;  at  Montreal,  1500  feet  at  least,  and  1200  feet  or 
more  for  the  Lake  Champlain  region.  A  similar  addition  is  required  also 
for  the  deductions  from  the  heights  of  all  terraces  and  beaches,  including 
those  of  the  region  of  the  Great  Lakes.  The  facts  prove  that  ice  barriers 
were  not  concerned  in  making  limits  for  the  lakes  ;  for  the  ice  had  retreated 


Map  of  Lake  Champlain  in  the  Champlain  period 
(transversely  lined),  with  the  existing  lake 
(cross-lined). 


CENOZOIC    TIME  —  QUATERNARY.  983 

to  the  north  of  them ;  that  salt  water  reached  up  the  St.  Lawrence,  then 
a  great  bay,  nearly  to  Lake  Ontario,  and  that  this  lake  lay  at  sea  level, 
receiving  the  tides,  although  freshened  in  its  waters  by  the  flow  from  the 
contributing  streams,  so  that  no  marine  remains  have  been  found  on  its 
borders.  It  also  appears  that  a  great  branch  bay  extended  from  the  St. 
Lawrence  northwestward  up  the  Ottawa  valley,  to  a  point  75  miles  beyond 
the  city  of  Ottawa,  and  another  southward  over  the  region  of  Lake 
Cham  plain. 

Moreover,  this  great  arm  of  the  sea,  500  to  600  feet  in  depth  of  water  at 
Montreal,  and  700  to  900  feet  in  Lake  Champlain,  besides  nurturing  Mollusks, 
was  a  sporting  ground  for  Seals,  Morses,  and  Whales.  Bones  of  the  Hump- 
backed Whale,  Megaptera  longimana,  have  been  reported  by  Dawson  as 
found  440  feet  above  the  sea  in  the  County  of  Lanark,  31  miles  north  of  the 
outlet  of  Lake  Ontario;  and  remains  of  the  White  Whale,  or  Beluga  (a 
species  related  to  the  Porpoise),  both  along  the  St.  Lawrence,  and  on  the 
borders  of  Lake  Champlain,  in  Vermont,  where  a  skeleton  was  found.  The 
latter  is  the  Delphinapterus  leucas  (  =  catodon)  or  "White  Whale,"  the 
Beluga  Vermontana  of  Z.  Thompson.  These  two  Arctic  species,  the  Hump- 
backed Whale  and  Beluga,  are  now  occasionally  met  with  in  St.  Lawrence 
Eiver. 

At  New  Haven,  Conn.,  an  even  slope  of  the  terrace  surface  is  continued  to  the  Sound, 
near  Savin  Rock,  and  appears  to  indicate  no  change  of  level  since  the  Champlain  period. 
But  on  the  borders  of  the  bay,  both  the  eastern  and  western,  there  is  a  terrace  of  20', 
which  is  safer  evidence  on  this  points 

South  of  Cape  Cod,  at  Sancati  Head  on  Nantucket,  the  beds  above  sea  level,  as 
described  and  represented  in  a  section  by  Desor  (1849),  consist,  at  base,  of  tilted  beds  of 
clay  ;  horizontally  above,  of  33'  of  beds  of  sand,  gravel,  and  clay  containing  fossils ;  42'  of 
sand  and  gravel  without  fossils  ;  and  then,  at  top,  of  1;  of  peat  and  6'  of  dune  sand.  The 
species  of  shells  in  the  beds,  according  to  Verrill  (1875),  are  kinds  now  inhabiting  the 
region,  those  of  the  lower  beds  indicating  a  summer  temperature  of  70°-75°  F.,  and  those 
above,  of  55°-60°  F.  Shaler  gives  a  full  account  of  the  geology,  with  Verrill's  list  of 
species,  in  Bull  53,  U.  S.  G.  8,,  1889. 

In  Maine,  shell-beds  occur  at  many  places  near  the  coast  —  at  Portland,  Cumberland, 
Brunswick,  Thomaston,  Cherry  field,  Lubec,  Perry,  etc.,  at  different  elevations  up  to  225' ; 
also  distant  from  the  coast,  at  Gardiner,  Hallowell,  Lewiston,  Skowhegan,  Clinton  Falls, 
and  Bangor.  At  Lewiston,  a  starfish  and  various  shells  were  found  in  a  bed  200'  above 
the  ocean  and  100'  above  the  Androscoggin  River;  at  Skowhegan, the  beds  are  150'  above 
the  ocean,  and  100'  at  Bangor  ;  near  Mount  Desert,  a  sea  bottom  deposit,  on  North  Haven 
Island,  is  217'  above  sea  level. 

The  beds  of  Maine  have  afforded  (Packard)  :  Pholas  crispata,  Saxicava  arctica, 
Mya  truncata,  M.  arenaria,  Thracia  Conradi,  Macorna  fragilis,  M.sabulosa,  Mactra  ovalis, 
Astarte  Banksii,  A.  elliptica,  A.  arctica,  Cardium  Islandicum,  Serripes  Grrcenlandicus, 
Leda  pernula,  L.  minuta,  Yoldia  glacialis,  Pecten  Grcejilandicus ,  P.  Islandicus,  Natica 
cZawsa,  Lunatia  heros,  L.  Grcenlandica,  etc. 

Shell-beds  occur  at  several  levels  and  many  localities,  along  the  St.  Lawrence,  as 
observed  by  Logan  and  Dawson.  Part  of  them,  as  Dawson  has  shown,  are  sea  beaches,  and 
others  are  offshore  deposits  — the  Leda  clays.  Beds  occur  west  of  Montreal,  near  Kempt- 
ville,  at  a  height  of  250';  near  Ogdensburg,  275',  and  also  near  Brockville  ;  near  the  city  of 
Ottawa,  450' ;  in  Winchester,  300' ;  in  Kenyon,  270' ;  in  Lochiel,  264'  and  290' ;  at  Hobbes 


984  HISTORICAL   GEOLOGY. 

Falls  in  Fitzroy,  350' ;  at  Dulham  Mills,  289' ;  in  the  counties  of  Renfrew,  Lanark,  Carl- 
ton,  and  Leeds,  425' ;  east  of  Montreal,  near  Upton  Station,  257' ;  farther  east,  on  the 
river  Gouffre,  near  Murray  Bay,  130'  and  360' ;  on  Prince  Edward  Island,  Tellina  Grcen- 
landica,  at  a  height  of  50'.  At  the  Straits  of  Belle  Isle,  Labrador,  the  deposits,  on  either 
side,  are  about  400'  above  the  sea ;  at  Chateau  Bay,  500',  probably  800'  in  some  parts 
(Packard)  ;  and  at  Nachvak,  1500'  (R.  Bell),  where  there  are  shell-beds.  In  Lake  Cham- 
plain,  the  shell-beds  extend  to  its  southern  extremity. 

The  Leda  clays  of  Dawson  afford  species  living  now  at  depths  less  than  100' ;  the  lower 
Leda  clays  containing  Tellina  Groenlandica  and  Leda  arctica;  and  the  upper,  species 
that  are  now  living  in  St.  Lawrence  Bay.  Of  the  higher  sand-beds,  Saxicava  rugosa 
is  the  common  species. 

The  more  common  shells  of  the  Montreal  beds  are  the  following  (Dawson)  :  Saxicava 
arctica,  Mya  truncata,  M.  arenaria,  Macoma  fragilis,  M.  sabulosa,  Astarte  Laurentiana, 
Mytilus  edulis,  Natica  clausa,  Yoldia  glacialis,  Trophon  clathratum,  Buccinum  Green- 
landicum. 

Among  the  species  at  Beauport,  there  are  the  following :  Lunatia  Grcenlandica, 
L.  heros,  Turritella  erosa,  Scalaria  Grcenlandica,  Litorina  palliata,  Serripes  Grcen- 
landicus,  Cardium  Islandicum,  Pecten  Islandicus,  Khynchonella  psittacea,  and  many 
others.  All  are  cold-water  species,  so  that  the  fauna  is  more  Arctic  in  character  than  that 
of  Montreal,  corresponding  with  the  fact  that  Montreal  is  150  miles  northwest  of  Beauport 
(Dawson). 

The  Capelin  (Mallotus  mllosus  Cuv.,  a  common  fish  on  the  Labrador  coast)  has  been 
found  fossil  on  the  Chaudiere  Lake  in  Canada,  183'  above  Lake  St.  Peter ;  on  the  Mada- 
waska,  206' ;  at  Fort  Colonge  Lake,  365'. 

On  the  Bay  of  Fundy  the  shell-beds  have  a  height  of  200-225',  and  on  the  Bay  of 
Chaleurs,  200'.  The  beds  descend  below  the  sea  level.  The  Leda  clays  of  the  latter 
region  contain  Leda  minuta,  L.  pernula,  Mya  arenaria,  M.  truncata,  Mytilus  edulis, 
Nucula  tennis,  Saxicava  rugosa  (most  common),  Macoma  calcarea,  Yoldia  arctica  (Leda 
truncata),  Buccinum  undatum,  Margarita  striata,  Natica  clausa,  Serripes  Grcenlandicus 
(abundant),  and  other  species  (Chalmers,  1885).  The  Saxicava  sand  in  the  Bay  of 
Fundy  contains  Mya  arenaria  and  Macoma  fusca  ;  but  shells  are  rare. 

On  the  coast  of  Labrador,  the  elevated  Champlain  beds  contain  mostly  the  same 
species,  both  those  of  the  Leda  clays,  and  the  overlying  beds.  Among  the  species  less 
abundant  farther  south,  or  not  at  all,  are  Cyclocardia  borealis  Con.,  Astarte  Banksii, 
Margarita  varicosa,  Turritella  reticulata,  T .  erosa,  Aporrhais  occidentalis,  Admete  viri- 
dula,  Bela  exarata,  B.  harpularia  Adams,  B.  robusta  Pack.,  B.  turricula,  Fusus  tornatus, 
F.  Labradorensis  Pack.,  Buccinum  undatum.  (Packard.) 

On  Grinnell  Land,  in  the  Arctic  seas,  shell-beds  resting  on  Miocene  have  an  elevation 
of  1000',  and  contain  the  usual  cold-water  species,  Mya  truncata,  Saxicava  rugosa,  Cardium 
Islandicum,  Astarte  borealis,  Pecten  Grcenlandicus,  etc.  (Feilden,  1877.) 

The  paper  on  the  Lake  Champlain  region,  with  a  map  by  S.  P.  Baldwin,  is  contained 
in  the  Amer.  Geol.,  xiii.,  1894.  Baron  de  Geer  (Proc.  B.  N.  H.  Soc.,  xxv.,  1892,  Amer. 
GeoL,  xi.,  1893)  gives  658'  for  the  marine  limit  at  St.  Albans ;  but  Baldwin  concludes 
that  the  terrace  at  this  level  was  that  of  a  glacial  lake. 


3.  Amount  of  subsidence  over  the  Western  Continental  border.  —  In  the  re- 
gion of  Mount  St.  Elias,  according  to  B-ussell,  deposits  of  moraine  material  4000 
to  5000  feet  thick  occur  in  the  Chaix  Hills ;  and  the  cliffs  of  Pinnacle  Pass, 
at  the  same  height,  contain  shells  of  the  Champlain  species  Mya  arenaria, 
Mytilus  edulis,  Leda  minuta,  Cardium  Islandicum,  Yoldia  limatula,  Thracia 
curta,  and  others.  B.  "Willis  has  reported  that  marine  beds  are  found  at  a 


CENOZOIC    TIME  —  QUATERNARY.  985 

height  of  1600  feet  on  the  borders  of  Puget  Sound,  but  nothing  is  further 
known  with  regard  to  the  formation.  G.  M.  Dawson  states  that  beds, 
probably  marine,  occur  at  Queen  Charlotte  Islands  and  along  the  Straits  of 
•Georgia  at  a  height  of  100  to  200  feet. 

Between  San  Francisco  and  San  Diego,  shore-lines  and  terraces  have  been  observed 
by  A.  C.  Lawson,  at  various  levels  up  to  1500' ;  but  no  marine  fossils  are  present,  so  that 
whether  Quaternary  or  Pliocene  is  uncertain.  The  heights  measured  near  San  Diego  are 
from  160'  to  700' ;  on  San  Pedro  Hill,  120'  to  1240' ;  on  San  Clements  Island,  from  12'  to 
1500' ;  the  Bay  of  Monterey,  near  Santa  Cruz,  from  96'  to  120',  part  of  them  showing 
grandly  from  the  bay.  Moreover,  the  Pliocene,  near  San  Francisco  (page  892),  has  now 
a  height  of  720'  above  sea  level. 

About  the  mountains  of  the  Interior  Plateau  of  British  Columbia,  as  stated  by  G.  M. 
Dawson,  there  are  extensive  terraces  5000'  to  5500'  above  sea  level ;  and  in  the  more 
.southern  part  of  the  plateau,  of  3900'  to  4900'.  But  they  afford  no  marine  fossils,  and 
their  origin  remains  unexplained.  Dawson  questions  whether  they  may  not  have  been 
made  by  superglacial  lakes. 

The  depths  of  the  submerged  river  channels  of  the  California  coast  (page  949)  indicate 
an  equal  subsidence  of  the  region,  if  the  channels  were  made,  as  is  believed,  during  the 
•Glacial  period. 

4.  The  Winnipeg- Lake  basin,  in  the  Central  Continental  Interior,  and  Hudson 
Bay.  —  The  former  discharge  of  a  river  from  55°  1ST.  in  the  Winnipeg  region, 
•down  the  Minnesota  into  the  Mississippi,  as  first  made  known  by  G.  K. 
Warren,  is  mentioned  on  page  947.  Later,  as  the  same  authority  pointed 
out,  the  region  then  elevated  had  subsided  and  become  the  area  of  a  vast 
lake.  The  outline  of  this  lake,  and  the  region  of  lakes  it  covers,  are  shown 
on  the  map,  Fig.  1548,  from  the  report  by  Upham,  who  named  the  lake,  Lake 
Agassiz.  Its  waters  extended,  according  to  the  map,  from  the  Minnesota 
divide  at  Traverse  Lake  in  45°  40',  over  the  Red  River  and  Winnipeg  region, 
to  55°  K  in  Manitoba,  nearly  half  of  the  whole  length,  700  miles,  being  in 
Minnesota.  The  upper  shore-line,  called  by  Upham  the  Hermann  Beach, 
was  traced  from  Lake  Traverse,  where  it  is  85  feet  above  this  lake,  and  1055 
feet  above  sea  level,  northward  for  more  than  300  miles,  where  the  height  about 
the  Brandon  Hills  is  1260  to  1269  above  sea  level,  and  about  560  feet  above 
the  present  level  of  Lake  Winnipeg.  This  shore-line  indicates,  therefore, 
a  great  Charnplain  depression  for  the  region  about  Winnipeg.  The  Hermann 
Beach  rises  northward  at  a  rate  of  six  inches  a  mile  near  Lake  Traverse,  to 
16  inches  to  the  northward,  bearing  evidence,  inasmuch  as  the  lines  were 
horizontal  when  made,  of  a  subsequent  elevation  that  increased  northward, 
the  time  of  which  was  probably  at  the  opening  of  the  Recent  period. 

Warren  accounted  for  the  non-discharge  of  the  great  lake  by  the  present 
outlet,  Nelson  River,  into  Hudson  Bay,  on  the  ground  of  a  land  barrier ;  and 
his  explanation  appears  to  be  sustained  by  the  course  of  events  of  the  period. 
For,  if  the  region  of  the  Laurentide  ice-plateau  about  Hudson  Bay  was 
elevated  3000  feet  or  more  in  the  Glacial  period,  the  continuation  into  the 
early  part  of  the  Champlain  period  of  only  a  small  portion  of  this  elevation 


986  HISTORICAL   GEOLOGY. 

would  make  all  the  barrier  needed.  The  pitch  of  the  land  about  Nelson 
Kiver  is  now  eastward,  and  the  rate  about  two  feet  a  mile. 

Upham  sets  aside  the  idea  of  this  change  of  level,  and  makes  the  lake  and 
the  southward  discharge  the  result  of  a  damming  by  the  ice-sheet  along  the 
northeast  border  of  the  lake.  For  details  of  his  observations  arid  his  view 
of  the  events  of  the  period,  the  reader  is  referred  to  his  elaborate  report 
already  mentioned.  On  the  slopes  leading  down  to  James  Bay,  the  southern 
extremity  of  Hudson  Bay,  marine  deposits  occur  up  to  a  height  of  450  feet 
above  the  level  of  Hudson  Bay,  indicating  that  the  Hudson  Bay  region  finally 
lost  all  its  elevation,  and  became,  further,  much  depressed.  This  is  part  of 
the  evidence  presented  by  Upham  to  prove  that  the  ice-dam  was  required. 
But  there  is  doubt  whether  the  retreating  ice  would  have  long  remained  a 
barrier  under  the  warm  climate  of  the  Cham  plain  period. 

5.  The  region  of  the  Great  Lakes.  —  Lake  Ontario,  now  247  feet  above  the- 
sea,  was  in  Champlain  time  at  sea  level,  at  the  head  of  the  long  St.  Lawrence 
Bay,  as  already  explained.  But  the  northern  and  southern  shore-lines  are 
widely  different  in  height,  owing  to  the  warping  of  the  surface  in  the  later 
reelevation.  North  of  the  middle  of  the  lake,  the  height  above  the  water 
surface  of  the  prominent  shore-line  or  beach  (called  the  Iroquois  beach  by 
Spencer,  who  mapped  its  position)  is  355  feet,  while  south  it  is  189  feet, 
whence  the  increase  in  height  northward  is  166  feet  in  a  distance  of  60 
miles.  At  the  east  end  of  the  lake  depression,  the  corresponding  heights 
are  483  feet  at  Watertown  and  194  near  Koine,  an  increase  northward  of  289 
feet  in  60  miles.  The  depth  of  the  lake  at  the  time  was  nearly  1000  feet  — 
equal  to  the  present  depth,  740  feet,  plus  the  mean  height  of  the  opposite 
shore-lines.  (The  positions  of  these  upper  shore-lines  are  given  on  the  map.) 

Westward  along  the  lake,  the  height  of  the  upper  shore-line  decreases, 
and  at  the  west  end,  200  miles  distant  from  the  east,  it  is  only  116  feet  —  a 
diminution  from  Watertown  of  367  feet  in  200  miles. 

Lake  Erie  is  now  326  feet  above  Lake  Ontario,  or  573  feet  above  sea 
level.  The  height  of  its  upper  shore-line  south  of  the  lake,  at  Cleveland, 
is  21 3  feet;  and  that  of  the  upper,  north  of  it  (the  Kidgeway  beach  of 
Spencer),  is  273  to  351  feet.  The  heights  increase  eastward.  The  upper 
at  the  west  end,  near  Fort  Wayne,  is  207  feet,  and  toward  the  east  end,  261 
feet.  The  mean  height  of  the  upper  line  south  of  the  lake  is  about  200  feet, 
and  the  same  is  true  as  regards  the  southern  shore-line  of  Lake  Ontario. 
The  fact  suggests  the  inference  that  the  heights  of  the  two  lakes  may  have 
had  the  same  difference  then  as  now.  Through  the  subsidence  the  lake  lost 
its  outlet  to  the  Ohio  —  the  Wabash  Eiver,  which  had  served  this  purpose, 
becoming  a  tributary  to  the  lake. 

Lake  Superior  is  now  602  feet  above  sea  level,  and  Michigan  and  Huron, 
582  feet.  The  latter  lakes  are  but  nine  feet  above  Lake  Erie. 

On  Lake  Superior,  the  upper  shore-line  of  the  north  side  has  a  height 
above  the  lake  at  Josephine  Mountain  —  50  miles  west  of  Thunder  Bay  — 
according  to  A.  C.  Lawson,  of  509  to  607  feet ;  at  Duluth,  the  west  end,  of  534 


CENOZOIC    TIME  —  QUATERNARY.  987, 

feet ;  and  that  of  the  south  side,  according  to  J.  B.  Taylor,  at  Marquette,  a 
height  of  588  feet;  at  Kimball,  90  miles  east  of  Duluth,  of  568  feet;  and  at 
Maple  Ridge,  25  miles  east  of  Duluth,  of  532  feet.  The  observations,  es- 
pecially those  on  the  north  side,  are  not  numerous  enough  to  give  the  mean 
height,  but  it  is  not  far  from  550  feet.  The  outline  of  Lake  Superior,  which 
these  shore-lines  indicate,  is  shown  on  the  map,  as  laid  down  by  Taylor. 

East  of  Georgian  Bay,  on  the  Nipissing  Strait  at  North  Bay,  Ontario, 
Taylor  obtained,  on  the  south  side,  the  terrace  height,  618  feet  above  the 
level  of  Lake  Superior,  and  on  the  north  side,  538  feet. 

At  the  south  end  of  Lake  Michigan,  the  height  of  the  upper  shore-line 
is  only  45  feet ;  at  Mackinac  Island,  in  northern  Michigan,  205  feet ;  south- 
west of  Huron,  267  feet. 

These  heights  of  the  upper  shore-lines  of  the  lakes  —  Superior,  Huron, 
Michigan,  and  Erie  —  are  widely  different,  yet  they  are  supposed  to  have 
been  the  heights  of  the  upper  shore-line  of  one  great  lake,  named  by  Spencer 
Lake  Warren,  after  G-.  K.  Warren. 

The  mean  height  of  550  feet  above  the  lake,  or  1152  feet  above  sea 
level  for  the  shore-lines  of  Lake  Superior  is  not  the  height  to  which,  in  the 
Champlain  period,  the  copious  waters  of  the  period  raised  the  surface  of  the 
lake ;  but  that  which  was  given  the  region  at  the  epoch  of  elevation  which 
closed  the  Champlain  period.  So  great  a  height  for  Lake  Superior  without 
a  barrier  at  the  outlet  to  Huron  and  Michigan  was  an  impossibility.  Lower 
shore-lines  exist  which  mark  successive  levels  in  the  waters  of  the  Lake 
Warren  region  during  the  progress  of  the  elevation  ;  and  an  upper  series  of 
these,  about  Huron  and  the  more  western  lakes,  is  the  Algonquin  beach  of 
Spencer. 

There  are  various  opinions  as  to  the  actual  height  of  Lake  Warren  above 
sea  level,  and  as  to  the  discharge  of  its  waters.  Discharge  by  Lake  Nipis- 
sing  into  the  Ottawa  and  St.  Lawrence  has  been  suggested.  The  uncertain- 
ties involve  the  condition  of  Niagara  Falls. 

The  present  heights  of  these  shore-lines  above  the  sea  for  the  four  western  lakes  — 
supposing  the  shore-lines  assumed  to  be  cotemporaneous  to  have  been  actually  so  —  are 
1100'  to  1200'  for  Lake  Superior ;  about  787'  for  Mackinac  Island,  between  Huron  and 
Michigan  ;  850'  for  southwest  Huron  ;  630'  for  the  south'  end  of  Michigan,  and  775'  for  the 
south  side  of  Erie.  As  to  actual  Champlain  heights,  that  is,  heights  before  the  elevation 
at  the  close  of  the  Champlain  period,  no  good  basis  for  a  conclusion  is  known  except  for 
Lake  Ontario,  which  was  at  tide  level. 

Supposing  the  height  above  sea  level  of  the  water  plane  of  the  combined  four  lakes  to 
have  been  600',  the  Superior  shore-lines  would  have  had  less  height  than  now  by  550' ; 
the  Mackinac  and  Huron  by  187'  and  230' ;  the  south  Michigan  by  30',  the  south  Erie  by 
175'.  But  with  the  water  plane  at  this  level,  Niagara,  if  in  the  course  of  discharge,  would 
have  had  a  fall  of  600'  —  a  condition  not  in  accordance  with  any  observed  facts. 

Again:  if  the  water  plane  of  these  lakes  were  about  300'  above  sea  level  (not  far 
from  the  present  height  of  Lake  Erie  above  the  level  of  Lake  Ontario),  Niagara  Falls 
would  have  been  like  the  modern  Niagara  in  height,  but  possibly  a  third  higher,  and  cer- 
tainly of  many  times  greater  volume  and  power,  owing  to  the  northern  drainage  from  the 
melting  ice-plateau. 


988  HISTORICAL  GEOLOGY. 

Again,  if  the  water  plane  were  at  or  near  the  sea  level,  as  is  sometimes  claimed, 
Ontario  would  have  been  in  the  combination,  and  there  would  have  been  no  Niagara  Falls 
until  the  elevation  at  the  opening  of  the  Recent  period.  The  idea  that  it  was  low  enough 
to  receive  salt  water  is  set  aside  by  the  absence  of  remains  of  salt-water  life. 

As  the  above  suppositions  suggest,  the  subject  has  its  many  doubts  ;  and  they  extend 
to  Niagara  Falls  as  well  as  to  lake  levels.  Many,  therefore,  are  the  diverse  geological  ex- 
planations. The  above  are  only  suppositions.  For  other  recent  views,  see  C.  K.  Gilbert's 
History  of  the  Niagara  River,  Smithsonian  Report  for  1890 ;  J.  W.  Spencer,  Amer.  Jour.  Sc. 
ior  1891  and  1894  ;  W.  Upharn,  ibid.,  Jan.,  1895  ;  and  F,  B.  Taylor,  ibid.,  April,  1895. 

Lake  Ontario  has  been  supposed  to  have  had  an  outlet  in  Champlain  time,  from  its 
southeastern  extremity  at  Home  by  the  Mohawk  River  to  the  Hudson,  on  the  ground  that 
the  St.  Lawrence  at  the  mouth  and  elsewhere  was  under  the  border  of  the  ice-sheet ;  and 
it  has  been  stated,  in  opposition,  that  the  Mohawk  flows  over  a  rocky  bottom  at  Little 
Falls,  at  a  height  of  370'  above  the  sea.  The  shell  deposits  on  the  St.  Lawrence  near  its 
mouth  at  a  height  of  600  feet,  are  evidence  that  the  ice  had  disappeared ;  so  that  its 
mouth  must  have  been  open  for  the  discharge  of  the  lake.  But  still,  since  the  Cham- 
plain  depression  at  Rome  was  194',  directly  east  at  Albany  near  350',  and  along  the  St. 
Lawrence  500'  to  600',  it  is  possible  that  all  northern  New  York  to  and  beyond  the 
Mohawk  was  sufficiently  depressed  for  the  more  southern  discharge. 

In  reply  to  the  suggestion  that  Lake  Superior  and  others  in  the  combination  may 
have  discharged  through  Pluron  and  Lake  Nipissing  into  Ottawa  River  and  thence  to  the 
St.  Lawrence,  it  has  been  stated  that  the  channel  beyond  Lake  Nipissing,  along  Mattawa 
River,  has  no  appearance  of  having  been  the  course  of  a  stream  larger  than  the  present 
(A.  Barlow,  in  letter  from  G.  M.  Dawson).  The  height  of  Lake  Nipissing  is  only  40'  above 
that  of  Lake  Superior,  and  the  highest  land  farther  east  is  but  25'  above  this,  while  the 
height  at  the  confluence  of  the  Mattawa  and  Ottawa  is  6'  below  the  level  of  Superior. 

Lakes  of  the  Great  Basin.  —  Among  the  flooded  lakes  of  the  Glacial 
and  Champlain  periods  none  have  greater  interest  than  those  of  the  Great 
Basin.  The  largest  of  them  are :  the  expanded  Great  Salt  Lake  of  Utah, 
or  Lake  Bonneville,  as  it  was  named  by  Gilbert  in  1876  in  honor  of  Captain 
Bonneville,  who  gave  the  first  account  of  the  existing  lake  after  a  visit  in 
1833 ;  and  Lake  Lahontan,  so  named  by  C.  King,  in  1878,  after  the  explorer 
La  Hontan.  The  former  lay  against  the  eastern  side  of  the  Great  Basin ; 
and  underneath  it  were  Lakes  Provo  and  Sevier,  as  well  as  the  Great  Salt 
Lake.  Great  Salt  Lake  was  quadrupled  in  length  and  increased  in  its  waters 
400  fold.  Lake  Lahontan  covered  the  localities  of  many  small  lakes  along 
the  western  side  of  the  Great  Basin.  Lake  Bonneville  is  described  at  length 
by  Gilbert  (1890),  and  Lahontan  by  King,  and  also  later  by  I.  C.  Kussell 
(1885).  The  lakes,  as  defined  by  Gilbert  and  Russell,  are  shown  on  the  map, 
Fig.  1548. 

There  are  a  number  of  terraces  about  both  regions  which  mark  the 
shore-lines  of  the  former  greater  lakes.  The  highest  terrace  of  Lake  Bonne- 
ville shows  that  at  maximum  flood  the  water  stood  1000  feet  above  the 
existing  level  of  Great  Salt  Lake. 

The  occurrence  of  two  sets  of  terraces,  and  of  two  sets  of  deposits  in  the  lake  area, 
one  of  clay  and  another  of  marl,  indicate,  according  to  Gilbert,  the  occurrence  over  the 
Great  Basin,  in  the  Quaternary  era,  of  two  epochs  of  floods,  and  of  a  dry  interval  between 
in  which  the  level  of  the  lake  was  reduced  from  1000'  to  200'  above  the  present  level. 


CENOZOIC   TIME QUATERNARY.  989 

King  and  Russell  deduced  nearly  corresponding  conditions  from  the  region  of  Lake 
Lahontan.  They  describe  large  depositions  of  tufa  during  a  warm  Interval  of  evapora- 
tion ;  and  a  second  deposition  during  the  final  desiccation.  The  latter  produced,  besides 
some  tufa,  a  mineral  which  became  changed  to  calcium  carbonate  (thinolite  of  King, 
page  133).  Lake  Mono  and  other  lakes  in  the  Basin  experienced  similar  changes. 

The  Great  Basin  owes  its  existing  dry  condition  to  (1)  the  feeble  amount  of  annual 
precipitation  (less  than  8  inches,  according  to  Schott's  chart)  and  (2)  the  great  evapora- 
tion caused  by  the  high  temperature  of  the  region.  The  precipitation  would  have  been, 
even  in  the  Glacial  period,  relatively  small ;  but  the  temperature  then  was  cold,  to  freez- 
ing, and  consequently  evaporation  became  relatively  small.  It  is  thus  argued  that  the 
lakes  of  the  Great  Basin  were  swollen  during  the  times  of  Glacial  cold,  owing  to  the  dimin- 
ished evaporation  and  some  melting  ;  that  floods  from  the  melting  at  the  time  of  the 
Glacial  retreat  would  have  added  largely  to  the  waters  and  carried  them  up  to  a  state  of 
maximum  height ;  that  the  waters  would  have  diminished  during  the  following  return  of 
glaciers  over  the  neighboring  mountains  ;  and  then  would  have  reached  a  second  maximum, 
when  melting  again  made  floods  under  the  warm  climate  and  abundant  precipitation  of 
the  Champlain  period.  The  floods  having  passed,  a  drier  climate  ensued ;  and  that  is. 
still  continued. 


EROSION,  TRANSPORTATION,  AND  DEPOSITION. 

To  Champlain  history  belong  the  events  that  occurred  during  the  time  of 
land  depression  and  warm  climate  of  the  Middle  Quaternary.  The  work  of 
erosion,  begun  in  the  later  Tertiary,  and  carried  on  over  the  continent  and 
about  the  newly  lifted  mountains  and  elsewhere  by  the  ice  and  waters  of  the 
Glacial  period,  was  continued  with  great  energy  through  the  earlier  part  of 
Champlain  time ;  and  the  results  are  to  be  seen  in  the  bold  and  crested 
heights  and  deep  canons  of  the  Rocky  Mountain  region,  and  in  deeply  cut 
gorges  over  a  large  part  of  the  land.  But  later  in  the  period,  transportation 
and  deposition  were  the  chief  work  of  the  rivers.  There  were  also  shallow- 
lakes  about  which  Mammals  congregated  and  left  their  bones  in  lacustrine 
deposits.  Peat  beds  and  marshes  abounded,  and  these  have  special  interest 
from  the  remains  of  Champlain  life  which  they  contain,  especially  the  heavy 
Herbivores  which  became  mired  in  them  in  their  efforts  to  escape  from 
pursuit.  Cave  deposits  also  have  prominent  importance,  they  having  been 
the  resorts  of  Carnivores,  Rodents,  and  other  species,  and  containing  also 
bones  of  the  various  animals  dragged  in  for  food.  And  as  the  caverns 
commonly  occur  in  limestone,  the  deposition  of  stalagmite  over  the  floor  of 
the  cave  has  often  enveloped  in  stone,  skeletons  and  their  fragments,  with 
other  relics  of  the  occupants. 

Champlain  seashores  also  have  their  deposits ;  and  by  means  of  their 
numerous  shells  and  other  fossils  of  shallow-water  and  beach-made  accumu- 
lations, they  mark  the  limits,  as  already  shown,  of  marine  submergence  in 
many  regions  from  which  the  sea  is  now  excluded. 

Fluvial  and  lacustrine  deposits.  —  The  Champlain  subsidence  diminished 
the  pitch  of  southward-flowing  rivers.  It  sometimes  reduced  it  to  zero, 
when  lakes  formed  if  there  was  room  for  them ;  and  occasionally  it  reversed 
the  direction  of  flow  in  a  stream.  Consequently  it  converted  excavating- 


990  HISTORICAL   GEOLOGY. 

rivers,  which  under  the  high  slopes  of  the  Glacial  period  had  produced  pro- 
found channels,  into  quiet  streams  that  made  fluvial  deposits  along  the  way, 
and  often,  when  in  gentlest  flow,  still-water  deposits.  It  has-  been  shown 
that  when  Champlain  time  began,  the  ice  had  already  retreated  to  the  moun- 
tains, and,  with  this  exception,  had  left  New  England  and  the  states  to  the 
westward.  Enough  ice  still  remained,  however,  to  give  waters  freely,  and 
some  floating  ice  also,  to  the  streams  which  had  their  sources  near  the 
borders. 

The  absence  of  the  ice  sheet  from  the  St.  Lawrence  valley  after  the  mak- 
ing of  the  lower  fourth  of  the  deposits,  is  proved  by  the  presence  in  the  beds 
of  shells  of  Mollusks  and  relics  of  other  species  that  lived  in  the  waters  when 
the  100-foot  level,  near  Montreal,  was  in  progress ;  and  also  in  Lake  Cham- 
plain,  when  but  50  feet  of  the  beds  had  been  laid  down.  Seals  and  Whales 
would  not  have  gone  beneath  the  ice  hundreds  of  miles  for  a  Champlain 
resort.  Moreover,  since  the  St.  Lawrence  River  makes  four  degrees  of  north- 
ing on  its  way  to  the  sea,  the  evidence  proves  that  the  clearing  from  ice 
extended  as  far  north  as  the  borders  of  Labrador. 

But  it  is  important  to  remember  that  the  river  valleys  were  to  some  extent 
the  courses  of  streams  in  the  Glacial  period,  and  therefore  that  beds  of  the 
Champlain  period  may  rest  on  others  of  clay  or  sand  which  are  Glacial  in 
period  of  formation.  Sometimes  these  fluvial  beds  of  the  Glacial  period  may 
be  distinguished  by  the  presence  of  bowlders ;  but  this  criterion  is  not  alto- 
gether safe,  since  floating  ice  of  the  Champlain  period  may  have  been  the 
source  of  the  bowlders.  At  the  North  Haven  clay-pits,  a  few  miles  north  of 
New  Haven,  the  straticulate  clays  contain  a  few  bowlders  two  or  three  feet 
in  diameter ;  and  it  was  in  one  of  these  clay-pits  that  the  two  bones  of  Arctic 
Eeindeer  were  found,  mentioned  on  page  946.  The  time  of  deposition  was 
probably  in  the  earliest  part  of  the  Champlain  period  or  the  later  of  the 
Glacial. 

Deposits  of  clay  appear  to  have  been  most  abundant  in  the  early  part  of 
the  Champlain  period,  after  the  subsidence  had  reached  its  extreme  limit, 
when  the  flow  of  the  streams  having  a  southward  course  was  feeble.  The 
later  increase  in  the  waters,  raising  the  flood  level,  involved  an  increase  in 
the  pitch  of  the  surface,  and  therefore  a  quicker  flow ;  and  then  sands  suc- 
ceeded to  the  clays,  and  in  many  regions  still  coarser  deposits,  ending  often 
with  the  coarsest  cobblestone  deposits  when  the  flood  was  at  its  height. 

The  stratification  of  the  deposits  hence  varies  from  the  most  regular,  or 
that  of  gently-moving  waters,  to  that  which  could  form  only  under  a  vast 
simultaneous  supply  of  gravel  or  sand,  and  water.  The  flow-and-plunge  style 
of  deposition  (page  93)  is  common.  Beds  of  this  kind  occur  with  others 
of  horizontal  bedding,  or  sometimes  locally  in  the  midst  of  coarse  gravel 
deposits,  such  stony  gravel  not  participating  in  it  because  of  its  coarseness. 
Very  often,  also,  the  beds  indicate  that  after  deposition  large  portions  had 
been  washed  away  by  some  local  rush  of  the  flooded  stream,  and  that  later 
the  excavations  thus  made  became  filled. 


CENOZOIC    TIME  —  QUATERNARY.  991 

The  tributaries  of  a  river,  when  torrential,  often  carried  into  the  valley 
great  quantities  of  gravel  and  stones,  and  made  river-border  deltas  on  a 
continuous  series  of  levels,  as  the  deposits  rose  in  height.  The  materials 
thus  received  were  stratified  in  part  by  the  waters  of  the  river,  the  finer 
portions  being  taken  up  and  drifted  on  to  make  the  finer  deposits  down 
stream.  The  delta-like  deposits  give  local  coarseness  and  irregularity  to  the 
beds  and  somewhat  greater  firmness,  so  that,  under  erosion,  they  sometimes 
are  made  to  stand  out  and  look  a  little  kame-like,  although  strictly  of 
fluvial  origin. 

Under  the  abundant  supply  of  water,  the  width  of  the  flood  grounds  or 
river  flats  in  many  large  valleys  became  increased  to  miles,  and  in  some 
cases  to  scores  of  miles.  Over  such  flood  plains,  through  all  the  progressing 
deposition  and  varying  velocities  of  flow  in  the  river  channel,  there  were,  as 
in  modern  flood  plains,  areas  of  relatively  quiet  waters,  where  beds  of  clay 
or  fine  earth  were  formed,  giving  the  valley-formations  a  great  diversity  of 
constitution.  Further:  rivers  in  some  places  became  dammed  by  floating 
ice  and  whatever  else  the  waters  transported,  as  now  in  modern  floods ;  and 
these  dams  were  the  cause  of  quiet  deposits  in  the  waters  above  them,  — 
that  is,  of  extensive  beds  of  clay  and  fine  sands  or  earth.  Through  the  two 
agencies,  subsidence  and  dams,  and  perhaps  in  a  few  cases  elevation  of  the 
land  toward  the  mouth  of  the  stream  or  elsewhere,  nearly  all  the  transi- 
tions in  the  nature  of  the  fluvial  deposits,  from  clays  to  the  coarsest  kinds, 
have  their  explanation.  The  height  of  the  highest  flood  plain  gives  approxi- 
mately the  height  of  the  maximum  flood. 

The  Champlain  deposits  along  valleys  or  about  lakes  are  usually  terraced. 
A  view  of  the  terraces  on  the  Connecticut  below  Hanover  is  given  on  page  195. 

The  following  figure  is  a  generalized  section  of  a  terraced  valley. 

1554. 


Section  of  a  valley,  with  its  terraces  completed. 

In  this  figure,  the  channel  which  the  river  occupies  at  low  water  is  at  E ; 
•ab,  a'6',  are  the  flats  either  side  which  become  flooded  in  modern  high 
freshets,  —  in  other  words,  the  flood-grounds ;  ef,  e'f,  are  the  flood-grounds 
of  the  river  (or  what  is  left  of  them)  during  the  great  Champlain  floods. 
The  intermediate  terrace-plains  are  other  levels,  formed  either  during  the 
rise  of  the  flood,  the  water  while  on  the  increase  flowing  long,  it  may  be,  at 
certain  levels ;  or  during  the  decline,  which  also  may  have  taken  place  by 
stages,  and  have  been  long  in  progress.  Part  may  be  under-water  levels ; 
for  great  streams  and  lakes,  or  lake-borders,  often  have  shoals  at  two  or 


992  HISTORICAL  GEOLOGY. 

three  levels ;  and  part  may  have  been  occasioned  by  the  contributions  of 
side  valleys,  and  unequal  resistance  to  wear.  On  account  of  this  feature 
the  formation  is  often  called  the  Terrace  formation. 

On  the  Connecticut  the  upper  flood  plain  or  terrace  is,  for  the  most  of  the  way,  150' 
to  250'  above  the  river.  Large  deposits  of  clay  occur  in  the  lower  part,  and  others  of  less 
extent  at  various  levels  to  the  top.  The  stream  owes  its  abundant  waters  to  the  high 
mountains  about  its  sources,  of  which  the  White  Mountains  were  the  highest.  The  depth 
of  water  may  have  been  50'  or  100' ;  there  is  no  basis  for  a  satisfactory  estimate. 

Along  the  Hudson  River  the  height  of  the  upper  terrace  is  100'  to  280',  and  finally 
340'  between  Albany  and  Schenectady.  As  before  stated,  the  heights  increase  to  the 
northward,  where  the  Champlain  subsidence  was  greatest. 

The  Connecticut  River  had  a  dam  at  the  narrows  below  Middletown,  Conn.,  as  the  fall 
off  in  the  terraces  below  it  shows  ;  another,  as  stated  by  B.  K.  Emerson,  near  Northamp- 
ton, Mass.,  between  the  opposite  trap  ridges,  Mount  Tom  and  Mount  Holyoke ;  and  possibly 
others.  Just  above  the  Northampton  dam,  where  the  upper  terrace-plain  is  about  200' 
above  the  river,  a  portion  of  the  flood-waters  escaped  over  the  west  bank  near  Florence, 
passed  to  the  west  of  Mount  Tom,  and  took  a  southward  course  along  the  Farmington  valley, 
as  the  levels  of  the  terrace-plain  show,  to  New  Haven,  Conn.,  where  it  was  discharged  by 
the  bay  into  the  Sound — resuming  thus  a  route  followed  by  the  whole  Connecticut  stream 
or  estuary  in  Triassic  time.  An  ice-dam,  or  drift-dam,  closed  a  narrow  gorge  through  the 
trap  ridge  above  Hartford,  Conn.,  which  was  the  channel  of  the  Farmington  River,  and 
another  deep  gorge  through  sandstone  above  Cheshire,  Conn.,  that  of  the  Quinnipiac  River,, 
so  that  the  new  discharge-course  of  the  Connecticut  secured  the  upper  parts  or  heads  of 
both  the  Farmington  and  Quinnipiac  rivers  as  its  tributaries,  and  took  possession  of  the 
valley  of  the  small  stream  called  Mill  River  to  reach  the  Sound.  On  the  terraces  of  the 
Connecticut  valley,  see  the  author's  papers  of  1870  to  1884  ;  also  E.  Hitchcock,  1841,  1857  ; 
C.  H.  Hitchcock,  Vermont  Geol.  Rep.,  1861,  and  New  Hampshire  Geol.  Hep.,  1878;  W. 
Upham,  New  Hampshire  Geol.  Rep.,  and  later  papers. 

W.  B.  Dwight  states  that  at  the  clay-beds,  near  Newburg,  north  of  the  Narrows,  the 
clay  fills  large  conoidal  depressions  in  the  sand-beds.  One  of  the  three  there  observed  is 
elliptical  in  section,  about  80'  by  50'  in  diameter  at  bottom,  150'  in  longer  diameter  at  top,, 
and  90'-100'  in  depth.  The  clay  is  straticulate,  the  layers  concave,  with  the  wall  of  the 
mass  rather  firm;  and  the  sand  and  gravel  beds  outside  bend  downward  at  the  walk 
The  clay  contains  a  few  bowlders. 

In  western  Pennsylvania,  plains  of  great  extent  have  a  height  of  275'  to  300'  along  the 
Monongahela,  and  of  300'  on  the  Ohio  5  miles  below  Pittsburg;  their  height  above 
the  sea  level  is  about  1050'.  Nothing  of  marine  origin,  however,  has  been  found  in  the 
region  to  suggest  the  presence  of  the  sea.  On  the  lower  Ohio  occur  terraces  160'  to  100'  in 
height  above  the  river.  They  exist  also  along  the  Mississippi  in  Kentucky,  and  farther 
south. 

Kettle-holes,  although  characteristic  of  many  moraines,  also  occur  at 
times  over  the  stratified  fluvial  deposits  of  the  Champlain  period.  An  exam- 
ple occurs  in  the  plain  on  which  the  city  of  New  Haven,  Conn.,  is  built,  one 
to  four  miles  north  of  the  center  of  the  city.  The  terrace  formation  of  the 
region  consists  chiefly  of  sand  and  fine  gravel.  The  small  depressions  repre- 
sented on  the  accompanying  map,  Fig.  1555,  are  the  kettle-holes.  They  are 
often  100  to  150  feet  in  diameter,  and  30  to  40  feet  deep.  The  ice  had  left 
the  region  long  before  deposition  of  the  beds  had  taken  place.  On  the  map, 
the  depression  in  the  plain  lettered  Beaver  Pond  Meadows  has  a  depth  of  25 


CEJS ozoic  TIME  —  QUATERNARY. 


993 


to  30  feet ;  and  the  kettle-holes  are  numerous  along  its  borders.  It  was  the 
course  of  a  deep  trench  made  by  the  southward-moving  glacier;  and  the 
depression  over  the  site  of  the  trench  was  left  in  the  sand  deposits  made  in 


1555. 


Kettle-holes  in  the  New  Haven  Terrace  formation,    figures  indicate  the  height  above  the  sea  level. 

1  inch  =  |  mile. 

the  trench.  The  trench  was  too  deep  to  be  filled  to  the  ordinary  level  of  the 
plain  by  the  deposition  of  the  sand  and  gravel,  and  hence  its  present  depth 
of  20  to  30  feet ;  and  the  kettle-holes,  which  border,  blend  with,  and  intervene 
between  them  were  probably  formed  under  the  same  conditions.  (Pages 
186,  193.) 

ELEVATION  CLOSING  THE  CHAMPLAIN  PERIOD. 

The  elevation  of  the  land  which  closed  the  Champlain  period  was  of  great 
extent  over  North  America.  The  high-level  shore-lines  already  described 
are  the  evidence,  they  marking  both  the  limit  of  the  Champlain  subsidence, 
and  the  fact,  though  not  necessarily  the  limit,  of  the  following  elevation.  Not 
the  limit;  for  the  present  height  of  these  elevated  shore-lines  is  the  final 
height  after  whatever  oscillations  of  level  may  have  in  the  mean  time 
occurred.  The  movement  may  have  carried  the  land  up  to  a  much  higher 
level  and  returned  it  to  its  present  position  without  leaving  any  distinct 
record. 

The  change  in  level  was  attended  by  a  change  also  in  climate,  from  a  warm 
climate  to  the  cooler  of  modern  time ;  but  to  a  climate  even  cooler  than  now 
if  the  level  at  the  first  was  higher  than  now.  It  is  certain  that  there  was  no 
return  of  the  ice-sheet ;  but  evidence  of  less  extreme  cold  may  yet  be  found 
about  the  local  glacier  areas  of  the  Rocky  Mountains,  and  possibly  about  the 
White  Mountains  of  New  Hampshire. 
DANA'S  MANUAL  —  63 


994  HISTORICAL   GEOLOGY. 

The  facts  reviewed  show  that  the  amount  of  elevation  east  of  the  Kocky 
Mountains,  over  the  northern  half  of  the  United  States  and  the  adjoining 
part  of  British  America,  increased  to  the  northward.  It  is  probable  that 
there  was  a  region  of  maximum  height  along  the  Canada  watershed  south 
of  Hudson  Bay  ;  since  the  height  of  a  shore-line  on  James  Bay  (Mo.)  is  only 
450  feet.  But  this  single  observation  leaves  the  question  doubtful.  The 
general  rule  of  increase  to  the  northward  holds  over  the  Winnipeg  region, 
as  is  shown  by  the  northward  rise  in  the  shore-lines  of  Lake  Agassiz ;  the 
upper  shore-line,  or  Herman  beach,  which  at  Lake  Traverse  is  85  feet  above 
this  lake,  or  1055  feet  above  sea  level,  has  a  height  at  the  national  boundary, 
224  miles  from  Lake  Traverse,  of  1230  feet,  and  76  miles  farther  north,  of 
1315  feet  (Upham). 

The  heights  increased  also  from  the  Atlantic  coast  westward.  But  there 
appears  to  have  been  a  maximum  east  of  Lake  Ontario,  the  heights,  as  has 
been  stated,  diminishing  120  feet  along  the  line  of  the  lake  between  Water- 
town  at  its  eastern  extremity  and  its  western  extremity.  The  region  may 
have  been  within  the  range  of  the  Appalachian  uplift  of  the  period  as 
suggested  by  F.  J.  H.  Merrill. 

How  far  the  change  in  level  extended  south  of  the  Great  Lakes  is  doubtful. 
The  small  elevation  of  the  shore-line,  45  feet,  at  the  south  end  of  Lake 
Michigan,  indicates  nearness  to  the  limit.  But  south  of  lakes  Ontario  and 
Erie,  the  distance  to  the  limit  may  have  been  two  or  three  hundred  miles 
or  more. 

Through  these  changes,  the  Arctic,  Labrador,  Canadian,  arid  New  England 
coasts  gained  much  in  extent,  and  so  also  some  parts  of  the  Pacific  border. 
Nova  Scotia  became  again  part  of  the  mainland.  The  beds  of  rivers  flowing 
south  had  their  pitch  increased  to  its  present  amount.  The  river  channels 
within  tidal  limits  were  excavated  to  a  deeper  level,  corresponding  more  or 
less  closely  with  the  amount  of  elevation  in  the  region ;  and  this  excavation, 
as  already  explained,  gave  additional  height  to  the  bordering  terraces.  Many 
lakes  were  drained  that  had  been  made  by  the  northward  depression  of  the 
land,  thus  carrying  forward  the  drying  of  the  continent  that  was  commenced 
with  the  subsiding  of  the  rivers. 

On  the  coast  of  Maine,  there  are  large  Indian  shell-heaps  of  the  common  Clam  (Venus 
mercenaria,  the  Quahog  of  the  Indians)  and,  in  some  places,  of  the  Virginia  Oyster,  spe- 
cies which  are  now  nearly  extinct  on  that  cold-water  coast.  As  made  known  by  Verrill, 
there  is  a  colony  of  living  southern  species  in  Quahog  Bay,  near  Bath  (20  miles  east 
of  Portland),  among  which  are  Venus  mercenaria  Linn.,  Modiola  plicatula  Lam.,  Ihja- 
nassa  obsoleta  Stimp.,  Urosalpynx  cinerea  Stimp.,  Crepidula  fornicata  Lam.,  Asterias 
arenicola  Stimp.,  Eupagurus  longicarpus  Edw.,  and  others,  reminding  one  strongly,  as 
Verrill  says,  of  the  coast  fauna  of  New  Haven,  on  Long  Island  Sound.  Further,  Venus, 
Ilyanassa,  Modiola,  and  other  species  occur,  according  to  Dawson,  also  in  Northumber- 
land Straits,  in  the  southern  part  of  the  Gulf  of  St.  Lawrence.  At  the  mouth  of  Dam- 
ariscotta  River,  30  miles  east  of  Portland,  there  is  the  only  locality  of  the  living  oyster 
north  of  Massachusetts  Bay.  Shells  of  Oysters,  Clams,  and  Scallops  (the  southern  Pecten 
irradians  Lam.)  are  abundant  in  the  deeper  portions  of  the  mud  of  the  harbor  of  Portland. 


CENOZOIC   TIME  —  QUATERNARY.  995 

W.  Upham  mentions  (1891)  the  occurrence  of  similar  warm- water  shells  in  the  vicinity 
of  Boston.  W.  F.  Ganong  reports  (1890)  that  similar  shells  have  been  found  in  Halifax 
Harbor,  Minas  Basin,  St.  Mary's  Bay,  and  on  other  parts  of  the  Acadian  coast. 

These  species  are  relics  of  a  past  southern  population ;  none  of  the  shells  are  found  in 
elevated  beaches  ;  and  hence  the  migration  from  south  of  Cape  Cod  took  place  hi  the 
Recent  period.  Such  a  migration,  extending  to  the  St.  Lawrence  Gulf,  was  not  possible, 
unless  the  Labrador  current  had  first  been  turned  aside  ;  and  a  closing  of  the  Straits  of 
Belle  Isle  would  have  brought  this  about.  This  implies  an  elevation  of  about  200  feet ; 
and  it  may  be  that  the  rise  which  introduced  the  Recent  period  carried  the  continent, 
to  the  north,  to  this  height  above  the  present  level.  In  the  Champlain  period  of  sub- 
sidence the  Straits  were  open,  this  being  proved  by  the  cold-water  shells  of  the  now 
elevated  beaches. 

FOREIGN. 

Whatever  the  facts  relative  to  interglacial  epochs  in  Europe,  it  appears 
to  be  certain  that  after  a  long  period  of  glaciation  there  was  a  time  of  widely 
extended  subsidence,  initiating  a  period  of  ameliorated  climate ;  and  that 
this  period  was  similar  to  that  of  the  Champlain  period,  not  only  in  this 
initiating  subsidence,  but  also  in  marine  deposits  and  other  phenomena. 
This  period  of  subsidence  in  Europe  had,  like  that  of  America,  its  sea-border 
formations  in  Sweden  and  Norway  closely  like  those  of  the  coasts  of  Maine 
and  the  St.  Lawrence,  even  to  the  "  Leda  clays  "  and  "  Saxicava  sands,"  and 
its  extensive  fluvial  formations  along  the  river  valleys.  According  to  J.  Geikie, 
the  submergence  of  Great  Britain  after  the  epoch  of  maximum  glaciation  was 
probably  500  feet.  This  author  inserts,  as  has  been  stated,  a  return  of 
glacial  conditions,  and  then  another  interglacial  before  the  Glacial  epoch 
generally  recognized  as  the  second ;  and  estimates  the  subsidence  of  Scotland 
during  this  second  interval  as  100  feet.  A  100-foot  terrace  forms  a  wide 
plateau  in  the  estuary  of  the  Forth.  The  depression  ten  miles  east  of  Glas- 
gow was  at  least  524  feet,  as  indicated  by  the  presence  of  marine  shells  in 
beds  of  clay,  which  are  overlaid  as  well  as  underlaid  by  beds  of  till.  The 
marine  shells  present  are  those  mainly  of  Arctic  seas,  like  the  St.  Lawrence 
species.  Among  them  are  Saxicava  rugosa,  Pecten  Islandicus,  Natica  clausa, 
Trophon  clathratum,  Yoldia  arctica,  Macoma  sabulosa. 

Northern  Germany  was  submerged  during  interglacial  time.  In  Sweden 
the  depression  exceeded  in  some  parts  600  feet.  Near  Uddevalla,  in  southern 
Sweden,  at  levels  of  200  to  400  feet,  shells  of  Mya  truncata,  Saxicava  rugosa, 
Astarte  borealis,  Natica  clausa,  Buccinum  Groenlandicum,  etc.,  are  in  great 
abundance ;  and  show  thereby  that  the  subsidence  was  of  long  continuance. 
Erdmann  concludes  that,  at  this  time,  the  Baltic  was  connected  with  the  North 
Sea,  over  the  region  of  lakes  from  Stockholm  westward,  and  with  the  Arctic 
Ocean  by  a  great  channel  leading  northeastward  over  Finland  to  the  White 
Sea.  The  Caspian  and  Aral  were  united  and  connected  with  the  Arctic  Ocean, 
and  so  continued  to  the  close  of  the  Champlain  period.  As  in  America,  the 
period  was.  the  time  of  flooded  rivers  and  lakes,  and  of  the  most  extensive 
freshwater  formations  in  the  world's  history.  Dupont  states  that  with  the 


996  HISTORICAL    GEOLOGY. 

close  of  the  floods  the  flood-grounds  of  the  river  Meuse,  near  Dinant  in 
Belgium,  were  diminished  in  breadth  from  seven  and  a  half  miles  to  a  fourth 
of  a  mile ;  and  this  is  an  example  of  the  general  change  over  Europe. 
Europe  also  had  rivers  dammed  up  by  gravel  and  sand  from  the  unlading 
glacier.  It  has  been  shown  that  the  Rhine  owes  its  present  channel  at  the 
Falls  at  Schaffhausen  to  its  having  been  forced  out  of  an  older  one  ;  and  it 
is  probable  that  the  Champlain  period  was  the  time  of  the  change. 

There  is  evidence  in  the  remains  of  Mammals  of  Malta  and  Sicily  that 
these  islands,  and  probably  Europe,  were  connected  at  this  time  with  Africa ; 
and  Britain,  as  the  ice  departed,  retained  for  awhile  its  connection  with  France, 
and  gave  passage  across  for  the  warm-climate  Mammals.  While  the  cold 
waters  of  the  North  Sea  were  thus  shut  off  from  the  British  Channel,  warm 
water  species,  from  the  coast  to  the  south,  were  living  in  the  channel. 

The  valley  of  the  Rhine  and  those  of  its  tributaries  contain  extensive 
deposits  of  Pleistocene  time.  The  material  of  the  alluvium  is  mostly  the  loess, 
a  line  yellowish-gray  loam,  much  of  it  unstratified,  —  generally  a  little 
calcareous  from  pulverized  shells ;  and  in  some  parts  it  contains  glacially 
marked  stones.  It  rests  in  some  places  on  stratified  gravel  or  sand.  Between 
Bale  and  Bingen,  this  alluvium  near  Bale  has  a  height  of  600  feet  above 
the  river;  and  through  much  of  it  there  are  land  and  freshwater  shells. 
Similar  facts  are  reported  from  most  of  the  river  valleys  of  Europe.  The 
deposits  on  the  Danube  are  as  extensive  as  those  of  the  Rhine ;  and  Suess 
states  that  stones  occur  in  it  that  were  probably  dropped  by  floating  ice. 

In  Belgium,  according  to  Dupont,  along  the  valley  of  the  Lesse,  and 
others,  the  limestone  caverns  situated  at  the  greatest  elevations  —  80  to  100 
feet  above  the  present  river  —  are  those  which  contain  the  older  remains  of 
Mammals ;  and  those  below  are  successively  more  recent  as  their  height  is 
less.  Moreover,  the  river  alluvium  shows  that,  when  the  upper  caves  were 
inhabited,  the  valley  was  filled  with  water  and  river-border  deposits,  nearly 
to  the  level  of  the  cave.  Thus  change  is  strikingly  exhibited. 

As  Nikitin  states,  "the  time  corresponding  to  the  ' interglacial  epoch' 
and  the  second  glaciation  of  the  Swedes  was  probably,  for  the  greater  part 
of  Russia,  the  epoch  of  the  formation  of  the  ancient  lake  deposits,  the  loess, 
and  the  upper  terraces  of  the  rivers,  which  constitute  the  principal  repository 
for  the  bones  of  the  Mammoth  and  other  extinct  Mammals,  which  abounded 
here  while  Scandinavia  and  Finland  were  still  covered  by  the  glacier." 

In  Europe,  a  reelevation  of  the  land  at  the  close  of  the  Pleistocene  was 
also  a  general  fact ;  but  the  rise  was  great  enough  to  make  a  partial  return 
of  glaciated  conditions  in  northern  Europe  and  about  the  Alps,  before  a 
settling  down  to  modern  levels  and  more  genial  climatal  conditions. 

The  absence  in  North  America  of  distinct  evidence  of  unusual  cold,  as  a 
consequence  of  the  elevation  closing  the  Champlain  period,  is  not  proof  that 
some  extension  of  glaciers  did  not  mark  the  close  of  this  period  in  Europe. 
For  Europe  has  had  glaciers  ever  since  over  the  Scandinavian  mountains  and 
the  Alps,  while  in  the  glaciated  part  of  eastern  America,  Mount  Washington 


CENOZOIC    TIME  —  QUATERNARY.  997 

is  the  only  peak  over  6000  feet,  and  but  a  very  small  part  of  it  is  as  high  as 
this.  The  Scandinavian  areas  are  in  much  higher  northern  latitudes. 

Geikie's  map  on  page  976  presents  the  views  of  many  European  geolo- 
gists with  regard  to  the  extension  at  this  time  of  the  Scandinavian  ice.  The 
only  countries  invaded  beyond  the  Baltic  are  Holland  and  northern  Germany. 
Eussia  was  free.  The  evidence  of  the  return  consists  chiefly  in  the  occurrence 
of  beds  of  peat  or  of  stratified  gravels,  sometimes  with  animal  remains, 
between  deposits  of  till.  In  the  Alps  such  intercalations  are  reported  from 
Durnten  in  the  Canton  of  Zurich,  in  St.  Gall,  and  elsewhere ;  and  in  some 
places  they  contain  bones  of  the  Elephant,  Rhinoceros,  Cave  Bear,  and  other 
Mammals  of  the  time. 

Further  evidence  of  a  partial  return  of  the  cold  consists  in  the  occurrence 
in  southern  France  of  remains  of  arctic  and  subarctic  Mammals,  among 
which  the  Reindeer  was  prominent ;  whence  the  epoch  is  named,  by  Lartet, 
the  Reindeer  epoch.  The  reelevation,  before  it  was  fully  completed,  cut  off 
the  Baltic  again  from  the  ocean  on  the  north  and  west ;  for,  as  Erdmann 
states,  while  on  the  upper  terraces  the  shells  of  the  Baltic  coasts  include  the 
outside  kind,  Yoldia  arctica,  the  open-sea  species  are  all  excluded  from  the 
lower  terraces,  excepting  a  few  Baltic  kinds,  of  which  the  Mytilus  is  the  most 
•common. 

LIFE   OF  THE  PLEISTOCENE,  OR  THAT  OF  THE  EARLY  AND  MIDDLE  QUATERNARY. 

It  has  been  already  stated  that  the  Plants  and  Invertebrates  (Mollusks, 
etc.)  of  the  Quaternary  are,  with  a  rare  exception,  living  species,  while  the 
Mammals  are  nearly  all  extinct.  Another  grand  feature  of  the  life  is  the 
great  size  of  a  large  part  of  the  Mammals,  Elephants  far  exceeding  modern 
Elephants,  and  the  same  with  other  Herbivores,  and  with  many  Carnivores, 
Edentates,  R/odents,  and  Marsupials.  The  genial  climate  that  followed 
the  Glacial  appears  to  have  been  marvelously  genial  to  the  species,  and  alike 
so  for  all  the  continents,  Australia  included.  The  kinds  that  continued  into 
modern  time  became  dwindled  in  the  change  wherever  found  over  the  globe, 
notwithstanding  the  fact  that  genial  climates  are  still  to  be  found  over  large 
regions.  Moreover,  it  was  during  and  after  the  final  melting  in  the  Cham- 
plain  period,  when  the  continents  were  everywhere  dripping  with  water,  that 
the  greatest  of  forests  covered  the  hills  and  prairies,  —  forests  that  in  the 
present  period  could  not  be  renewed  without  an  impracticable  amount  of 
artificial  irrigation,  and  which  hence,  through  forest  fires,  have  given  way  in 
America  to  prairies. 

BRUTE  MAMMALS   AND  INFERIOR  SPECIES. 
NORTH  AMERICAN. 

North  America  was  prominently  the  continent  of  Herbivores ;  Carnivores 
were  relatively  few.  The  most  widely  distributed  species  and  one  of  the 
largest  was  the  Elephas  primigenius.  It  ranged  from  Georgia,  Florida, 


998 


HISTORICAL   GEOLOGY. 


1556. 


Texas,  and  Mexico  on  the  south  to  Canada  on  the  north,  and  Oregon  and 
California  on  the  west,  and  lived  also  in  Alaska  and  over  the  interior  plateau 

of  British  Columbia  north  of  the  glaciated 
area.  Moreover,  it  was  an  inhabitant  of 
Britain,  of  nearly  all  Europe,  and  of  northern 
Asia.  It  was  a  hairy  species,  as  some  Russian 
specimens  have  shown,  and  was  thereby 
fitted  for  life  in  cold-temperate  latitudes. 
The  species  was  over  twice  the  weight  of 
the  largest  modern  Elephant  and  nearly  a 
third  taller.  One  of  the  teeth,  from  Ohio, 
a  fourth  the  natural  size,  is  shown  in  Fig. 
1556.  The  American  Elephant,  excepting 
the  variety  in  the  remote  northwest,  has- 
been  regarded  until  recently  as  a  distinct 
species  and  called  Eleplias  Americanus.  The  chief  difference  is  in  the  teeth, 
the  plates  of  enamel  being  less  closely  crowded  than  in  the  European. 

Another  Elephant-like  species,  of  still  larger  size,  was  the  Mastodon 
Americanus,  a  restoration  of  which,  ^g-  the  natural  size,  by  Marsh,  is  given 
in  Fig.  1557.  Fig.  1558  represents  one  of  the  teeth,  a  fourth  the  natural  size 

1557. 


Tooth  of  Elephas  primigenius  (x 


Fig.  1557,  Eestoration  of  Mastodon  Americanus  (x  ^g),  by  Marsh ;  1558,  Tooth  of  same  (x  J). 

lineally.  The  remains  of  the  species  are  met  with  most  abundantly  over  the 
northern  half  of  the  United  States,  though  occurring  also  in  the  Carolinas, 
Mississippi,  Arkansas,  and  Texas.  They  are  found  also  in  Canada  and 
Nova  Scotia.  The  best  skeletons  have  been  dug  out  of  marshes,  in  which 
the  animals  had  become  mired.  The  skeleton  here  figured  was  from  a  marsh 


CENOZOIC    TIME  —  QUATERNARY. 


999 


in  Otisville,  Orange  County,  N.Y.,  and  is  now  in  the  Yale  Museum.  One 
bog  in  New  Jersey  near  Hackettstown  is  reported  to  have  afforded  portions 
of  six  skeletons.  When  alive,  the  height  must  have  been  12  or  13  feet,  and 
the  length,  adding  7  feet  for  the  tusks,  24  or  25  feet.  Remains  of  the 
undigested  food  have  been  found  with  the  skeletons,  showing  that  it  lived 
in  part  on  spruce  and  fir  trees.  J.  Collett  states  that  a  skeleton  found  in 
Indiana  contained  between  the  ribs  "  a  crushed  mass  of  herbs  and  grasses, 
similar  to  those  which  grow  in  the  vicinity  "  ;  and  the  bed  of  clay  contained 
also  some  modern  freshwater  and  land  shells ;  and  he  concludes  that  the 
extinction  of  the  species  must  have  been  a  comparatively  recent  event. 

The  Horse,  Equus  excelsus,  was  a  fit  cotemporary,  as  Leidy  observes,  of 
the  Mastodon  and  Elephant.  Several  other  species  of  Equus  have  been 
found  in  North  America,  showing  that  North  America  was  abundantly  pro- 
vided with  Horses  in  Champlain  time,  though  not  having  among  them  the 
modern  Horse,  E.  caballus. 

The  Cervalces  Americanus  of  Harlan,  a  species  related  to  the  Elk,  and 
Stag,  as  the  name  implies,  was  of  greater  size  than  the  famous  Irish  Deer, 
Cervus  giganteus.  It  had  much  larger  legs  and  a  very  large  head.  Harlan's 


1559. 


Antlers  of  Cervalces  Americanus  (x  jg).     Scott,  '85. 


specimen  was  from  Natchez,  Miss.  The  head  and  antlers,  by  W.  B.  Scott,  of 
a  specimen  from  Warren  County,  New  York,  are  represented  of  reduced  size 
in  Fig.  1559. 

Bison  latifrons  L.  was  a  Bison  or  Buffalo,  much  larger  than  the  existing 
Buffalo,  which  lived  in  the  Mississippi  and  Ohio  valleys,  and  over  the 
Southern  States  to  Texas.  There  were  also  species  related  to  the  Musk  Ox, 
Ovibos  bombifrons  and  0.  cavifrons. 


1000 


HISTORICAL    GEOLOGY. 


Gigantic  Edentates,  species  related  to  the  Sloth  and  Armadillo,  of  the 
genera  Megatherium,  Mylodon,  Megalonyx,  Glyptodon,  and  others  were  also 
in  the  North  American  fauna,  although  most  characteristic  of  South  America. 
Their  remains  have  been  found  at  Natchez  in  Mississippi,  in  Florida,  and  in 
Georgia,  South  Carolina,  Texas,  Kentucky,  Oregon,  and  elsewhere. 

Remains  of  the  Megatherium  mirabile  of  Leidy  were  found  in  Georgia, 
at  Skiddaway  Island,  and  in  South  Carolina.  Megalonyx  is  another  genus  of 

these    large    Sloth- 

156°-  like    animals.      Its 

species  occur  over 
the  Pampas  of 
South  America,  to 
the  Straits  of  Ma- 
gellan ;  but  the  first 
known  was  found  in 
Virginia,  in  Green- 
brier  County,  and 
was  named  Megalo- 
nyx by  Jefferson,  in 
allusion  to  its  large 
Its  bones  have  also  been  found  at  Big-Bone  Lick,  Ky., 


Claw  of  Megalonyx  Jeffersonii  (x  £). 


claws  (Fig.  1560). 
and  elsewhere. 

A  North  American  Mylodon,  M.  Harlani,  has  been  found  both  east  and 
west  of  the  Mississippi,  and  in  Oregon. 

Rodents  were  represented  by  the  gigantic  Castoroides  Ohioensis,  related 
to  the  Beaver  (Castor  Canadensis).  The  Beaver  has  a  length,  exclusive  of 
the  tail,  of  about  three  feet ;  the  Castoroides  was  nearly  or  quite  five  feet 
long.  Its  remains  have  been  found  in  New  York,  Ohio,  and  south  to 
Mississippi  (Natchez). 

The  Peccary,  Dicotyles  nasutus,  has  been  found  near  Squankum,  N.  J., 
and  in  Virginia. 

Among  Carnivores,  a  Lion,  Felis  atrox,  from  Natchez,  was  about  as  large 
as  that  of  Britain.  There  were  also  Bears,  as  the  Ursus  amplidens  of 
Leidy,  from  the  same  locality,  and  the  Arctotherium  simum  of  Cope,  from 
Shasta  County,  Cal. 

The  Equus  beds  of  Marsh  (1877)  are  deposits  of  Pleistocene  Mammals, 
occurring  over  various  parts  of  western  North  America,  from  Mexico  and 
Texas  to  Oregon  and  western  Nebraska.  It  has  been  questioned  whether 
they  were  not  of  later  Pliocene  age.  Many  have  afforded  remains  of  four 
species  of  Equus,  Elephas  primigenius,  Mastodon,  Megatheridce,  Glyptodon, 
Machcerodus  (Smilodon),  and  other  kinds. 

The  marine  species  of  the  St.  Lawrence  and  the  borders  of  Canada  and 
New  England,  in  contrast  with  the  terrestrial,  were  cold-water  species, 
and  show  that  the  Straits  of  Belle  Isle,  between  Newfoundland  and  Labrador, 
were  very  widely  opened  by  the  subsidence  of  the  Champlain  period. 


CENOZOIC    TIME  —  QUATERNARY.  1001 

Fig.  1561  represents  the  bones  of  the  head  of  the  Vermont  Cetacean, 
Delphinapterus  leucas,  mentioned  on  page  983  as  frequenting  the  expanded 
<!hainplain  Bay  of  the  time.  It  was  probably  about  14  feet  in  length. 

1561. 


Delphinapterus  leucas  (x  J).     Z.  Thompson,  1853. 


The  Equus  beds,  in  central  Kansas,  McPherson  County,  have  afforded  (1891)  Equus 
major  and  a  species  of  Megalonyx  (M.  Leidyi  Lindahl).  The  beds  consist  of  gravel,  sand, 
and  clay,  with  a  layer  of  fine  sand  marl  above,  and  indicate  shallow  water  and  marsh  con- 
ditions. In  the  Smoky  Hill  Valley,  the  beds  contain  remains  of  Elephants,  Horses,  Dogs, 
Camels,  and  Platygonus ;  similar  remains  are  found  in  the  valley  of  the  Salomon 
(Williston). 

In  a  forest  bed,  overlying  the  Erie  Clays  (page  972),  and  covered  by  stratified  sands 
and  clays,  Newberry  found  remains  of  the  Champlain  species  of  Mastodon,  Elephant,  and 
Castoroides. 

Bones  of  Elephas  or  Mastodon,  Equus,  an  Ox,  Llama,  occur  in  gravels  of  the 
Lahontan  basin,  Nevada. 

Florida  has  afforded,  according  to  Leidy,  from  the  Alachua  Clays  of  Archer  and 
Ocala,  remains  of  Elephas  Columbi,  Mastodon  Floridanus,  Ehinoceros  proterus,  Hippo- 
therium  ingenuum,  Auchenia  major,  A.  minor,  Machcerodus  Floridanus,  etc.  ;  and 
from  the  Peace  Creek  beds,  Manatee  County,  several  of  the  above  species,  with  Equus 
_fraternus,  Bison  Americanus,  Megalonyx  Jeffersonii,  and  a  species  of  Glyptodon  scarcely 
distinguishable  from  a  South  American  form.  Some  mixture  of  Quaternary  with  earlier 
species  at  these  localities  is  suspected.  In  Cuba,  De  Castro  found  the  bones  of  a  huge 
Sloth,  later  named  Megalocnus  rodens  by  Leidy  ;  and  from  the  caves  of  Anguilla,  one  of 
the  Windward  Islands,  have  come  a  gigantic  Kodent  related  to  the  Chinchilla,  as  large 
as  the  Virginia  Deer,  Amblyrhiza  inundata  Cope,  besides  other  species  of  the  genus. 
The  facts  point  to  a  Quaternary  connection  of  Florida  and  the  Western  Islands  with 
South  America. 

A  vertical  opening  in  the  limestone  strata  at  Port  Kennedy,  eastern  Pennsylvania, 
•described  by  C.  M.  Wheatley,  has  afforded  remains  of  a  large  number  of  species  of 
extinct  Mammals,  the  animals  having  fallen  into  it  as  into  a  trap.  As  identified  by  Cope, 
the  bones  belong  to  34  species  and  72  individuals,  and  include  2  Tapirs  ( T.  Americanus 
L.  and  T.  Haysii),  a  Bear  (Ursus  pristinus'),  a  Fdis,  an  Ox,  a  Horse,  the  American 
Mastodon,  several  species  of  Megalonyx,  one  of  Mylodon,  M.  Harlani  Owen,  several 
Kodents,  and  a  Bat ;  Cope  observes  that  11  were  warm-climate  species,  and  3  North  Ameri- 
can Arctic.  A  cave  in  Wythe  County,  Va.,  and  another  near  Galena,  111.,  contain  some 
«extinct  species  along  with  others  that  are  living.  In  another  near  Carlisle,  Penn. ,  Baird 


1002  HISTORICAL   GEOLOGY. 

found  bones  of  all  the  species  of  Mammals  of  the  state,  besides  one  or  two  other  species 
not  now  Pennsylvanian,  but  known  in  regions  not  far  remote  ;  as  a  general  rule,  the  bones 
of  the  cave  appear  to  indicate  that  the  size  of  the  species  exceeded  that  at  the  present 
time. 

In  western  Canada,  Chapman  has  found  remains  of  the  modern  Beaver,  Muskrat, 
Elk,  and  Moose,  in  stratified  gravel  which  contained  also  bones  of  the  Mammoth  and 
Mastodon. 

At  Kotzebue  Sound  have  been  found  Equus  major,  Alces  Americanus,  Eangifer 
caribou,  Ovibos  moschatus,  O.  maximus,  0.  cavifrons,  Bison  crassicornis  (=  B.  antiquus 
Leidy),  but  no  Mastodon  remains. 

The  Quaternary  deposits  have  afforded  Marsh  remains  of  the  Birds,  Meleagris  altus 
Mh.,  and  M.  celer  Mh.  (Turkeys),  from  New  Jersey  ;  Grus  proavus  Mh.r  ibid.  ;  and 
Catarractes  affinis  Mh. ,  from  Maine. 

SOUTH  AMERICAN. 

In  South  America,  over  100  species  of  extinct  Quaternary  quadrupeds 
have  been  made  out.  The  bones  occur  in  great  numbers,  over  the  prairies 
or  pampas  of  La  Plata,  in  the  "  Pampean "  formation,  and  in  the  caverns: 
of  Brazil ;  and  they  include  thirty  or  more  species  of  Rodents  (Squirrels,. 
Beavers,  etc.),  species  of  Horse  of  the  genera  Hippidium  and  Equus,  Tapir, 
Lama,  Stag,  Dicotyles;  species  of  Macrauchenia ;  a  Mastodon  different  from 
the  North  American;  Hyena;  Wolves;  half  a  dozen  Panther-like  beasts, 
which  occupied  the  caverns  of  Brazil ;  and,  among  Edentates.  Ant-eaters, 
12  or  14  species  related  in  tribe  to  the  Megatherium  (Sloth  tribe),  and  a  dozen 
or  more  related  to  the  Armadillo  and  Glyptodon.  They  number  more  species 
than  now  exist  in  that  part  of  the  continent,  and  were  far  larger  animals. 

1562. 


EDENTATE.  —  Megatheriu 


The  Edentates  were  the  most  remarkable.  The  animals  of  this  order  are 
stupid  in  aspect  and  lazy  in  movement  and  attitude. 

The  Megatherium  (M.  Cuvieri  Desmarest,  Fig.  1562)  exceeded  in  size  the 
largest  Rhinoceros.  The  length  of  one  of  the  skeletons  is  18  feet.  Its 
massy  limbs  were  more  like  columns  for  support  than  like  organs  of  motion. 


CENOZOIC    TIME  —  QUATERNARY. 


1003 


The  femur  was  three  times  as  thick  as  an  elephant's ;  the  clumsy  tibia  and 
fibula  were  soldered  together;  the  huge  tail  was  like  another  hind  leg, 
making  a  tripod  to  support  the  heavy  carcass  when  the  animal  raised  itself 
against  a  tree  and  slowly  wielded  its  great  arms  ;  and  the  hands  terminating 
the  arms  were  about  a  yard  long,  and  ended  in  long  claws.  The  teeth  had  a 
grinding  surface  of  triangular  ridges,  well  fitted  for  powerful  mastication. 

A  fourth  allied  genus  is  Scelidotherium,  of  which  seven  South  American 
species  have  been  made  out,  —  one  as  large  as  the  Megalonyx,  and  one  smaller 
than  a  Tapir. 

Of  the  armor-clad  kinds,  the  genus  Glyptodon  (Fig.  1563)  contained  several 
gigantic  species.  These  animals  had  a  shell  something  like  that  of  a  Turtle, 
In  the  G.  davipes  Owen, 
the  length  of  the  shell, 
measuring  along  the 
curve,  was  five  feet. 

It  has  been  found 
that  in  the  restoration 
of  this  species  (Fig. 
1563)  the  tail  is  that  of 
a  species  of  the  allied 
South  American  genus, 
Hoplophorus. 

The  following  figure, 
from  a  photogravure  of  the  specimen  in  the  La  Plata  Museum  at  Buenos 


1563. 


EDENTATE.  —  Glyptodon  clavipes  (x  ^0)  ;  the  tail,  that  of  a  Hoplophorus. 


1564, 


EDENTATE.  —  Doedicurus  clavicaudatus.     From  a  photogravure  in  a  paper  by  Lydekker. 

Ayres,  published  by  Lydekker  (1894),  represents  another  Pampean  species; 
the  club-tailed  Glyptodont,  Do&dicurus  clavicaudatus. 

Lydekker  states  (1894)  that  "  marvelous  as  are  all  the  Glyptodonts,  this 


1004  HISTORICAL    GEOLOGY. 

is  the  most  astounding  in  the  series.  Its  monstrous  skeleton,  as  mounted  in 
the  museum,  is  over  11  f  feet  long;  the  carapax,  across  the  back,  10^  feet 
wide ;  the  massive  club-like  terminal  tube  of  the  caudal  sheath,  over  3  feet 
11  inches  long.  The  plates  of  the  carapax  are  oblong  plates  of  bone,  smooth 
•externally,  but  perforated  by  from  one  to  five  large  circular  holes  through 
which  quill-like  bristles  were  doubtless  protruded  during  life.  The  tremen- 
dous club  bears,  at  its  flattened  and  expanded  extremity,  a  number  of 
roughened,  oval,  depressed  facets,  which  must  have  given  support  to  huge 
horny  spines  not  unlike  the  horns  of  a  Rhinoceros.  The  whole  animal 
must  have  bristled  with  horns  and  quills,  a  little  like  some  giant  Porcupine." 

Another  Glyptodont,  the  Panochthus,  rivalled  the  Doedicurus  in  bulk. 

The  genus  Ghlamydotherium  included  other  mailclad  species  in  which  the 
carapax  consisted  of  movable  bands ;  one,  more  Armadillo-like,  was  as  large 
as  a  Rhinoceros. 

Such  were  the  characteristic  animals  of  Quaternary  South  America.  The 
largest  Edentates  of  the  existing  period  are  but  three  or  four  feet  in  length. 
The  Megatherium  probably  exceeded  more  than  one  hundred  fold  the  bulk  of 
any  living  Edentate. 

EUROPEAN  AND  ASIATIC. 

The  Mammals  of  Quaternary  Europe  are  equally  remarkable  for  their 
great  size.  Caverns  in  Britain  and  Europe  were  the  dens  of  gigantic  Lions, 
Bears,  and  Hyenas,  while  Herbivores,  equally  gigantic,  compared  with  modern 
species,  roamed  over  the  continent,  from  the  Mediterranean  and  India  to  the 
Arctic  seas.  The  remains  are  found  in  the  earthy  or  stalagmitic  floors  of 
caverns  ;  mired  in  ancient  marshes ;  buried  in  river  and  lacustrine  alluvium, 
or  sea-border  deposits ;  or  frozen  and  cased  in  Arctic  ice. 

In  Great  Britain,  the  Mammals  have  been  found  in  river  border  forma- 
tions, in  a  large  number  of  localities ;  and  several  of  these  have  afforded 
also  relics  of  man.  The  loess  of  the  Rhine  and  the  valley  formations  of 
other  parts  of  Europe  have  afforded  similar  facts.  The  European  caves 
were  mostly  caves  of  Bears  (the  great  Ursus  spelceus),  while  those  of 
England  were  occupied  by  Hyenas  (Hycena  spelcea),  with  fewer  Bears.  The 
Cave  Hyena,  although  of  unusual  size,  is  now  regarded  as  of  the  same  species 
with  the  Hywna  crocuta,  of  South  Africa;  and  the  Cave  Lion,  or  Felis 
spelcea,  as  a  variety  of  Felis  leo,  or  the  Lion  of  Africa. 

In  a  cavern  at  Kirkdale,  one  of  the  earliest  explored,  Hyena  bones  and 
teeth  belonging  to  about  300  individuals  were  mingled  with  remains  of  the 
extinct  species  of  Elephant  or  Mammoth  (Elephas  primigenius),  Rhinoceros 
(R.  tichorhinus),  Hippopotamus  (H.  major),  Ox.  three  kinds  of  Deer,  along 
with  the  Cave  Lion,  Brown  Bear  (Ursus  arctos),  Wolf,  Fox,  Horse  (Equus 
caballus),  Hare,  Rabbit,  Water  Rat,  besides  the  Pigeon,  Lark,  Duck,  etc. 
The  Hyenas  dragged  into  their  caves  the  dead  carcasses  they  found,  and 
lived  on  the  bones,  and  also  on  the  bones  of  fellow  Hyenas ;  and  the  bottom 


CENOZOIC   TIME QUATERNARY. 


1005 


1565. 


of  the  cave  is  often  covered  with  the  fragments.      Calcareous  excrements 
are  also  abundant,  quite  similar  to  the  excrements  of  the  modern  Hyena. 

The  common  species  of  Elephant  in  the  county  of  Norfolk,  on  the  North 
Sea,  was  the  Eleplias  primigenius.  It  lived  in  herds  over  England,  and 
extended  its  wanderings  across  the  Siberian 
plains  to  the  Arctic  Ocean  and  Bering  Straits, 
and  beyond  into  North  America ;  but  it  seems 
not  to  have  gone  far  south  of  the  parallel  of 
40°.  It  is  stated  by  Woodward  that  over 
2000  grinders  were  dredged  up  by  the  fish- 
ermen of  the  little  village  of  Happisburgh, 
in  the  space  of  13  years,  and  other  localities 
in  and  about  England  are  also  noted. 

This  ancient  Elephant,  as  Siberian  speci- 
mens have  indicated,  had  its  body  covered 
with  a  reddish  wool  and  long  black  hair. 
One  of  the  tusks  measured  12|-  feet  in 
length.  At  the  beginning  of  this  century, 
one  of  these  animals  was  found  at  the 
mouth  of  the  Lena,  frozen  and  encased  in 
ice.  It  measured  16  feet  4  inches  in  length, 
to  the  extremity  of  the  tail,  exclusive  of  the 
tusks,  and  9  feet  4  inches  in  height.  It 
retained  the  wool  on  its  hide,  and  was  so 
perfectly  preserved  that  the  flesh  was  eaten 
by  the  dogs.  The  remains  are  exceedingly 
abundant  at  Eschscholtz  Bay,  near  Bering 
Straits,  where  the  ivory  tusks  of  ancient 
generations  of  Elephants  are  gathered  for 
exportation. 

The  Rhinoceros,  R.  tichorhinus,  spread 
from  England  to  Siberia,  and  was  a  hairy 
species  like  the  Elephant.  A  frozen  speci- 
men found  near  Wilui,  in  Siberia,  in  1772, 
was  111  feet  long,  and  had  a  hairy  skin. 
Another  widespread  species  was  the  ft. 
hemitcechus. 

The  Irish  Deer,  Cervus  giganteus  was  another  of  the  gigantic  species. 
Skeletons  have  been  found  in  marl,  beneath  the  peat  of  swamps,  in  Ireland 
and  England,  and  fragments  in  the  bone  caverns.  The  height,  to  the  summit 
of  the  antlers,  in  the  largest  individuals,  was  10  to  11  feet ;  and  the  span  of 
the  antlers  was  10  feet,  and  in  one  specimen  over  12  feet.  It  is  supposed 
that  it  may  have  been  extinct  but  a  few  centuries. 

The  modern  Horse,  Equus  caballus,  but  of  unusual  size,  has  been  found 
in  the  deposits  of  the  period  over  all  Europe,  northern  Asia,  and  northern: 


Canine  tooth  of  the  Cave  Bear. 


1006  HISTORICAL   GEOLOGY. 

Africa.  An  Ox  of  the  period,  the  Aurochs,  still  lives  under  the  protection 
of  the  Russian  Czar ;  and  another,  Bison  priscus,  the  Urus,  was  alive  in  the 
time  of  the  Romans. 

Kent's  Hole,  near  Torquay,  has  afforded  bones  of  the  Mammoth,  Rhinoceros  (J?. 
tichorhinus},  Cave  Bear,  Cave  Lion,  Cave  Hyena,  Wolf,  Fox,  Irish  Deer,  Reindeer, 
Machcerodus  laiidens,  Horse,  besides  relics  of  Man  in  the  form  of  flint  implements ;  and 
the  Brixham  Cave,  in  the  same  vicinity,  in  addition  to  flint  implements,  bones  of  the 
Cave  Bear,  Brown  Bear,  Grizzly  Bear  (U.  ferox),  Elephant,  Cave  Hyena,  Cave  Lion, 
Wolf,  Fox,  modern  Horse,  Reindeer,  Goat,  Irish  Deer,  Elk,  modern  Hare  and  Rabbit, 
Wild  Boar,  Lagomys  spelceus,  Aurochs  (Bos  primigenius),  etc. 

In  France,  in  the  older  caves,  according  to  Lartet,  the  bones  of  the  Mammoth  pre- 
dominate along  with  R.  tichorhinus,  the  Cave  Hyena  and  Lion,  etc.,  and  in  the  later  (the 
Reindeer  epoch),  those  of  the  Reindeer.  Remains  of  the  Reindeer  have  been  found  on 
the  southern  slopes  of  the  Pyrenees.  Elephas  antiquus  and  Rhinoceros  hemito&chus 
with  the  Hyena,  Horse,  Elk,  Wild  Boar,  Bos  primigenius,  occur  as  far  south  as  Gibraltar 
in  the  "  Ossiferous  fissures  "  of  the  Gibraltar  Rock  ;  but  E.  primigenius  and  R.  tichorhinus 
are  unknown  in  Spain. 

On  Sicily  have  been  found,  besides  the  Gibraltar  species,  remains  of  Hippopotamus 
Pentlandi,  H.  major,  and  Elephas  Africanus  ;  and  on  Malta,  besides  several  of  the  species 
of  Sicily,  a  pigmy  Elephant,  3'  to  5'  high,  E.  Melitensis  Falc. ;  with  also  the  Bear,  Ursus 
arctos,  a  species  of  Wolf,  a  Stag,  and  other  kinds.  These  species  of  Sicily  and  Malta  are 
the  evidence  of  a  dry  land  connection  with  Africa,  and  probably  across  to  Europe. 

AUSTRALIAN. 

In  Australia,  the  living  species  are  almost  exclusively  Marsupials ;  and 
they  were  Marsupials  also  in  the  Quaternary,  but  of  different  species.  As 
on  the  other  continents,  the  moderns  are  dwarfs  by  the  side  of  the  ancient 
species.  The  Quaternary  Diprotodon  (Fig.  1566)  was  as  large  as  a  Hippo- 
potamus, and  somewhat  similar  in  habits,  the  skull  alone  being  a  yard  long; 
and  Nototherium  Mitchelli  Owen,  an  herbivorous  species,  was  as  large  as  a 
bullock;  one  of  the  Kangaroos,  a  species  of  Macropus,  had  the  size  of  a 
Rhinoceros. 

From  this  review  of  Quaternary  Mammals,  it  is  apparent  that  the 
characteristic  species  of  each  continent  were  mainly  of  the  same  type  that 
now  characterizes  it.  Both  in  the  Quaternary  and  at  the  present  time,  the 
Orient  is  strikingly  the  continent  of  Carnivores ;  North  America,  of  Herbi- 
vores ;  South  America,  of  Edentates ;  Australia,  of  Marsupials. 

The  facts  sustain,  moreover,  the  view  that  the  period  in  which  these 
Mammals  lived  and  thrived  was  one  of  warm  climate.  The  species  which 
have  been  mentioned,  with  a  very  few  exceptions  noted  below,  must  have 
required  a  climate  ranging  between  warm  temperate  on  one  side,  and  extreme 
cold  temperate  on  the  other ;  and  this  range  belonged  to  the  wide  region  from 
middle  Europe  and  Britain  to  northern  Siberia,  where  herds  of  Elephants, 
hairy  Rhinoceroses,  and  other  Mammals  found  abundant  vegetation  for  food, 
and  a  good  living  place.  If  northern  Siberia  had  then  the  mean  temperature 
now  found  in  southern  Scandinavia,  or  40°  F.,  instead  of  its  present  5°  F.  to 
10°  F.,  central  Europe  would  necessarily  have  been  within  the  warm  temperate 


CENOZOIC    TIME QUATERNARY. 


1007 


zone.  One  cause  of  such  a  climate  may  have  been  the  extensive  submergence 
of  northern  lands,  giving  an  unusual  sweep  northward  to  the  G-ulf  Stream  and 
the  corresponding  warm  current  of  the  Pacific.  Perhaps  in  the  earlier  part 
of  the  period,  before  the  glacier  had  disappeared  from  northern  Europe  and 
America,  Arctic  Asia  was  still  very  cold ;  but,  long  before  its  close,  the 
Elephants  had  taken  full  possession,  as  the  vast  abundance  of  their 
remains  attests. 

1566. 


Restoration  of  Diprotodon  Australis  by  Owen. 

The  migrations  of  the  species  from  Europe  to  southern  England  took 
place  as  the  Glacial  era  closed,  but  before  the  Champlain  subsidence  had 
taken  place — this  event,  as  in  America,  having  been  delayed  until  the  retreat 
of  the  ice  had  made  great  progress. 

The  rarity  of  remains  of  Quaternary  Mammals  in  Scotland  and  Ireland, 
in  contrast  with  England  and  Wales,  where  they  have  been  found  in  over 
150  localities,  has  been  attributed  by  Dawkins  to  the  lingering  of  the  ice  about 
the  Scotch  and  Irish  mountains. 

The  cold  that  followed  the  Champlain  period,  or  that  of  the  Reindeer  era 
of  Lartet,  appears  to  have  brought  destruction  among  the  northern  tribes 
of  Europe  and  Asia,  and,  at  the  same  time,  to  have  driven  southward  the 
more  active  survivors,  or  those  which  had  the  best  chance  for  escape.  The 
encasing  in  ice  of  huge  Elephants,  and  the  perfect  preservation  of  the  flesh, 
shows  that  the  cold  finally  became  suddenly  extreme,  as  of  a  single  winter's 
night,  and  knew  no  relenting  afterward.  The  existence  of  remains  of  the 
Reindeer  in  southern  France,  of  the  Marmot,  also  a  northern  species,  and  of 


1008  HISTORICAL   GEOLOGY. 

the  Ibex  and  Chamois,  now  Alpine  species,  is  attributed  by  Lartet  to  the- 
forced  migration  thus  occasioned.  In  the  caves  of  Perigord  (Dordogne,  etc.), 
the  bones  of  the  Eeindeer,  far  the  most  abundant  kind,  lie  along  with  those 
of  the  Cave  Hyena,  Cave  Bear,  Cave  Lion,  Elephant,  and  Rhinoceros,  as  well 
as  Horse  and  Aurochs. 

Lartet  says  that,  in  the  drift  or  valley  gravels,  the  Elephant,  Rhinoceros, 
Horse,  and  Ox  are  the  predominant  species,  and  the  Reindeer  appears  spar- 
ingly ;  while,  in  the  Dordogne  caves,  the  Reindeer  predominates,  being 
associated  in  large  numbers  with  the  Horse  and  Aurochs,  and  exceptionally 
with  remains  of  the  Elephant,  Hyena,  etc.  With  the  Mammals  of  the  Rein- 
deer era,  in  southern  France,  there  are  also  great  numbers  of  Grouse  and  the 
Snowy  Owl,  species  which  have  since  returned  to  northern  Europe.  The 
Reindeer  was  living  in  Scotland  until  near  the  end  of  the  twelfth  century. 
The  absence  of  remains  of  the  Reindeer  and  other  subarctic  species  from 
Spain  and  Italy,  and  the  southern  character  of  the  Champlain  fauna,  are 
evidence  that  the  cold  did  not  extend  beyond  the  Alps  and  Pyrenees.  At 
the  same  time,  the  presence  of  abundant  remains  of  the  Reindeer  in  Belgian 
deposits  of  this  era,  without  bones  of  the  extinct  Mammals,  may  be  evidence 
that  the  cold  of  Belgium  was  severe  enough  to  drive  off  the  old  warm  climate 
quadrupeds.  An  isothermal  chart  shows  that  England  would  have  had  a 
warmer  climate  than  Belgium.  The  Quaternary  fauna  of  Britain  and  Europe, 
and  the  caves  are  discussed  at  length  by  W.  Boyd  Dawkins  in  his  works  on, 
Cave-Hunting,  Early  Man  in  Britain,  and  in  later  papers. 


MAN. 

The  relics  of  Man,  through  which  his  geological  history  has  been 
deciphered,  are:  (1)  buried  human  bones;  (2)  stone  arrow-heads,  lance- 
heads,  hatchets,  pestles,  etc. ;  (3)  flint  chips,  made  in  the  shaping  of  stone 
implements;  (4)  arrow-heads  or  harpoon-heads,  and  other  implements,  made 
of  horns  and  bones  of  the  Reindeer  and  other  species ;  (5)  bored  or  notched 
bones,  teeth,  or  shells;  (6)  cut  or  carved  wood;  (7)  bone,  horn,  ivory,  or 
stone,  graven  with  figures  of  existing  animals,  or  cut  into  their  shapes, — 
one  example  of  which,  found  by  Lartet,  in  the  bone  cave  of  La  Madelaine 
Perigord,  and  representing  the  old  Hairy  Elephant,  is  here  given;  (8)  mar- 
row-bones broken  longitudinally,  in  order  to  get  out  the  marrow  for  food ; 

(9)  fragments  of  charcoal,  and  other  marks  of  fire  for  warming  or  cooking  ; 

(10)  fragments  of  pottery.     Relics  of  the  above  kinds  occur  in  the  deposits 
of  the  "  Stone  Age." 

In  later  deposits,  of  Recent  time,  occur  bronze  implements,  without  iron 
—  marking  a  "Bronze  Age,"  \  and,  still  later,  iron  implements,  or  those  of 
the  "  Iron  Age  " ;  and  here  occur,  as  fossils,  coins,  inscribed  tablets  of  stone, 
buried  cities,  as  Nineveh  and  Pompeii,  etc. 

The  "  Stone  Age,"  here  referred  to,  is  properly  the  Stooie  Age  of  Euro- 


CENOZOIC   TIME QUATERNARY.  1009 

pean  or  Oriental   history.     The   Stone   Age  in  North  America,  or  a  large 
part  of  it,  continued  in  full  force  till  within  two  centuries  since. 
The  principal  facts  with  regard  to  human  relics  are  these :  — 

1.  Stone  implements  occur  intimately  associated  with  the  remains  of  the 
Cave  Bear,  Cave  Hyena,  Cave  Lion,  the  old  Elephant  and  Rhinoceros  and 
other  extinct  species,  with  some  remains  of  the  Reindeer  and  other  living 
Mammals,  in  deposits  of  the  Champlain  period,  if  not  earlier,  —  the  Paleo- 
lithic epoch,  proving  the  existence  of  Man  at  that  time. 

2.  Similar  implements,  along  with  others  of  horn  and  bone,  and  draw- 
ings of  animals,  and  other  markings,  occur  in  southern  France,  as  well  as 
more  to  the  north,  in  caves  and  river-border  deposits,  along  with  great  num- 
bers of  bones  of  the  Reindeer,  with  other  northern  species  now  existing,  and 

1567. 


Elephas  primigenius  ;  engraved  on  ivory  (xg). 

also  with  the  remains  of  the  extinct  Urus,  Elephant,  Cave  Bear,  Cave  Hyena, 
Cave  Lion,  etc.,  and  also  the  now  living  Aurochs,  Ibex,  Elk,  etc.,  pertaining 
to  the  MesolitMc  or  Reindeer  epoch,  or  that  of  the  "  second  Glacial  epoch  "  of 
Europe.  And,  with  these  relics,  human  bones  and  even  complete  skeletons 
have  been  found ;  the  marrow  bones  of  the  Reindeer  and  Aurochs  so  split  as 
to  show  that  they  were  broken  by  Man  for  the  marrow;  and  charcoal  and 
other  relics  of  fires,  probably  used  both  for  cooking  and  for  warmth;  for  the 
weather  must  have  been  sometimes,  if  not  generally,  cold. 

3.  The  skeletons  of  the  Reindeer  epoch  of  southern  Europe  are  in  part 
those  of  tall  men.  One  of  them,  that  of  the  cave  of  Mentone  in  the  Medi- 
terranean (just  east  of  Nice),  according  to  its  describer,  Mr.  Riviere,  was 
that  of  a  man  six  feet  high,  with  a  rather  long  but  large  head,  high  and 
well-made  forehead,  and  very  large  facial  angle  —  85°.  The  woodcut  on  the 
next  page,  made  from  a  photograph,  published  by  Riviere,  represents  the 
skeleton  as  it  lay,  partly  uncovered  from  the  stalagmite,  with  Mediterra- 
nean shells  and  flint  implements  and  chippings  lying  around,  and  a  chaplet 
of  stag's  canines  across  the  skull.  The  Mentone  cave  contained  also  bones 
of  the  Cave  Lion,  Bear,  and  Hyena,  Rhinoceros  tichorhinus,  Wolf,  and  other 
species,  but  not  the  Reindeer.  There  are  nine  of  these  caves  on  this  border 
DANA'S  MANUAL  —  64 


1010 


HISTORICAL   GEOLOGY. 

1568. 


CENOZOIC   TIME QUATERNARY.  1011 

of  the  Mediterranean.  A  similar  skeleton  was  obtained  from  the  cave  of 
Cro-Magnon,  in  Perigord,  France,  whose  height  was  5  feet  11  inches,  and 
another  at  Grenelle,  about  5  feet  10  inches.  These  are  referred  to  the  Rein- 
deer epoch. 

The  human  remains  of  caverns  on  the  Lesse  valley,  in  the  vicinity  of 
Lie"ge,  Belgium,  first  discovered  by  Schmerling  in  1833-1834,  are  regarded 
as  unquestionably  Paleolithic.  They  belonged  to  less  tall  men;  the  cranium 
was  high  and  short,  and  of  good  Caucasian  type,  though  of  medium  capacity ; 
"a  fair  average  human  skull,"  observes  Huxley.  But  one  Belgian  jaw-bone, 
from  the  cave  of  the  Naulette,  has  several  marks  of  inferiority,  for  example, 
remarkable  thickness  and  small  height ;  the  molar  teeth  increasing  in  size 
backward,  the  posterior  or  "wisdom-tooth"  being  the  largest  (besides  having 
five  roots),  while  the  reverse  is  the  case  in  civilized  man;  the  prominence  of 
the  chin  wanting.  Fragments  of  crania  and  of  some  other  bones  were  found 
with  the  jaw-bone. 

The  human  crania  of  the  caves  of  Furfooz  in  Belgium,  of  the  Reindeer 
era,  are  described  as  intermediate  between  the  broad  and  long  types,  and  as 
"  Mongoloid,"  approaching  those  of  the  Finns  and  Laplanders.  The  height 
of  the  men  was  not  over  four  and  a  half  feet,  and  thus  they  were  like  exist- 
ing Man  of  Northern  Europe ;  and  it  may  be  that  Laplanders  were  driven 
south  by  the  cold,  as  well  as  Reindeers.  The  habits  of  the  people,  according 
to  Dupont,  were  like  those  of  the  Esquimaux. 

Chipped  flints  have  been  reported  by  F.  Noetling  from  the  Upper  Miocene 
or  Lower  Pliocene  of  Burma  (1894)  ;  the  bed  affording  them  lies  beneath 
4620  feet  of  Pliocene  and  contained  also  remains  of  Rhinoceros  Perimensis 
and  Hipparion  Antelopinum. 

The  remains  of  Paleolithic  Man  found  in  North  America  are  sufficient  to 
confirm  the  conclusions  from  those  of  Europe.  But  the  evidence  is  not  of 
the  same  satisfactory  character,  inasmuch  as  the  precise  age  of  the  deposits 
is  in  dispute,  and  the  localities  have  not,  in  general,  been  verified  by  a 
succession  of  discoveries. 

Professor  J.  D.  Whitney  described  many  years  since  a  skull,  from  Cala- 
veras  County,  Cal.,  which  was  found,  according  to  the  owner  of  the  mining 
claim,  at  a  depth  of  130  feet  from  the  surface,  underneath  the  lava-bed,  in 
1866.  Doubts  of  its  authenticity  have  been  expressed  by  others  who  have 
examined  the  evidence ;  but  Whitney,  in  his  latest  publication  on  the  sub- 
ject (On  the  Auriferous  Gravels  of  the  Sierra  Nevada,  1879),  refers  to 
corroborating  testimony,  and  gives  it  full  credit.  Whitney  also  mentions 
the  discovery  of  flint  implements  in  the  Auriferous  gravel  in  other  parts  of 
California.  The  fossil  plants  of  the  gravels  are  referred  to  the  Pliocene  (or 
partly  Miocene)  by  Lesquereux.  The  few  Mammalian  remains  include  the 
Champlain  Mastodon  and  Elephant,  but,  in  some  places,  Pliocene  species. 
Some  recent  land  shells  were  contained  in  the  earth  filling  the  cranium. 
The  skull,  according  to  Jeffries  Wyman,  resembles  that  of  a  modern  Indian, 
especially  the  Esquimaux,  but  has  a  more  prominent  forehead  and  a  larger 


1012  HISTORICAL   GEOLOGY. 

chamber  within.  These  high  qualities  of  the  "Calaveras"  skull  are  part 
of  the  objection  which  has  been  brought  forward  to  its  being  of  Pliocene 
Tertiary  age,  and  the  Neolithic  character  of  accompanying  implements  is 
another  part. 

Flint  implements  have  been  described  by  C.  C.  Abbott  from  stratified 
drift,  along  Delaware  Eiver,  near  Trenton,  N.J.  The  deposits  in  which 
they  occur  are  probably  of  Champlain  age.  At  Loveland  and  Madison- 
ville,  Ohio,  C.  L.  Metz  found  chipped  implements  in  deposits  of  loess  and 
stratified  gravel.  N.  H.  Winchell  has  reported  the  discovery  of  imple- 
ments of  polished  stone  and  copper,  with  human  bones,  in  terraced  and 
stratified  deposits  near  Minneapolis.  In  the  loess  of  the  Missouri  valley, 
Neb.,  according  to  Aughey  (1874),  two  chipped  implements  were  found, 
associated  with  the  vertebra  of  an  Elephant.  McG-ee  reports  his  discovery 
of  a  chipped  obsidian  implement  in  the  deposits  about  Lake  Lahontan, 
Nev.  Hartman's  Cave,  near  Stroudsburg  in  Monroe  County,  Penn.,  has 
afforded  T.  D.  Paret,  and  later  H.  C.  Mercer,  teeth  of  the  Reindeer,  a  tooth 
of  the  American  Bison,  and  remains  of  Dicotyles  Pennsylvanicus,  Castoroides 
Ohioensis,  Horse,  Lynx,  Gray  Fox,  Wolf,  Skunk,  Beaver,  Woodchuck,  Musk- 
rat,  with  a  bone  fish-hook,  bone  awls,  harpoon,  etc.  There  is  apparently  a 
mixture  in  the  cave  of  Pleistocene  and  Recent.  In  Brazil,  human  remains 
were  found  many  years  since,  by  Lund,  in  caverns,  along  with  extinct  Quater- 
nary Mammals ;  and  Clausen  has  reported  the  occurrence  of  pottery  in  a 
bed  of  stalagmite  containing  these  Mammals. 

4.   RECENT  PERIOD. 

After  the  great  alternations  in  level  and  in  climate  of  the  Early  and 
Middle  Quaternary,  the  earth  appears  to  have  reached,  as  the  Recent  period 
opened,  one  of  its  stages  of  relative  quiet.  The  excavation  of  valleys,  the 
distribution  of  earth  and  gravel  over  the  rugged  surface,  and  the  filling  of 
valleys  with  drift  and  alluvium  had  prepared  the  way  for  Man,  the  domi- 
nant species  of  the  period.  At  the  final  stage  in  the  preparation,  the  Brute 
Mammals  had  become  diminished  in  size,  and  greatly  also  in  number  of 
species. 

But  the  geological  agents  of  change  are  still  at  work  —  the  air,  rivers, 
ocean,  heat,  chemical  forces  and  interior  causes  of  earth  movements  ;  and 
thereby  rock-deposits  are  still  in  progress :  metamorphism  and  vein-making 
by  quiet  methods ;  volcanoes  with  somewhat  lessened  activity ;  and  upward 
and  downward  changes  of  level.  Absolute  equilibrium  and  rest  will  not  be 
attained  until  the  earth  no  longer  contracts  from  cooling  and  waters  cease 
to  move  and  transport. 

In  the  organic  kingdoms,  interactions  among  species,  and  conflicts  with 
natural  conditions,  are  producing  variation  in  Recent  time  as  hitherto,  but 
with  this  prominent  difference :  that  Man,  on  leaving  the  wilderness,  and 
taking  full  possession,  became  a  powerful  agent  of  modification  and  exter- 


CENOZOIC   TIME  —  QUATERNARY. 


1013 


mination.  In  conforming  to  the  old  organic  law,  kill  and  eat,  he  is  like  his 
predecessors.  But  his  necessities  lead  him  to  drive  wild  nature  from  her 
grounds,  in  order  to  secure  room  for  his  farms  and  dwellings;  and  in  the 
process,  species  of  plants  and  animals  are  fast  becoming  extinct.  Man's 
carelessness,  moreover,  has  made  destructive  fires  among  forests  common. 

Neolithic  Man.  —  The  earlier  deposits  of  the  Eecent  period,  made  by 
human  agency,  are  his  shell-heaps  found  especially  along  coasts,  those  of  the 
coasts  of  Danish  Islands,  in  the  Baltic  —  called  KjokJcen-modding  or  Kitchen- 
middens,  and  similar  accumulations  at  other  localities.  They  contain  no 
remains  of  the  Reindeer,  showing  that  the  glacial  cold  had  receded  toward 
its  present  limits,  while  those  of  the  Urus,  /Stag,  Roedeer,  Wild  Boar,  Dog, 
Wolf,  and  other  existing  species  are  common. 

In  Denmark  and  elsewhere  occur  polished  stone  implements,  with  broken 
pottery,  and  bones  of  existing  quadrupeds,  and  among  them  those  of  the 
domesticated  Dog,  but  no  remains  of  either  the  extinct  Quaternary  Mammals 
or  the  Eeindeer.  The  Neolithic  human  remains  of  Denmark  indicate  the 
same  small,  round-headed  race,  Laplander-like,  that  were  found  in  the 
Reindeer  caves  of  Belgium. 

In  the  same  era,  or  perhaps  a  little  later  in  the  Neolithic  era,  existed  the 
oldest  of  the  lake-dwellings  of  Switzerland  (dwellings  in  lakes,  on  piles, 
such  as  Herodotus  described  over  2000  years  since).  They  have  afforded 


1569. 


1570. 


Human  skeleton,  from  Guadaloupe. 


Conglomerate,  containing  coins. 


stone  implements  and  pottery,  with  remains  of  Goats,  Sheep,  the  Ox,  as 
well  as  the  Dog,  but  not  the  Reindeer  or  any  extinct  species;  also,  of 
Wheat  and  Barley ;  also  a  human  skull,  neither  very  long  nor  very  short, 
but,  according  to  Rutimeyer,  much  like  those  of  the  modern  Swiss.  These 


1014  HISTORICAL  GEOLOGY. 

Neolithic  structures  occur  mainly  about  the  eastern  lakes,  Constance  and 
Zurich,  while  those  of  the  "  Bronze  Age  "  are  found  in  the  western  lakes. 

Lake-dwellings  or  "  stockaded  islands,"  called  Crannoges,  have  been 
found  in  peat-bogs  in  the  British  Isles,  and  especially  in  Ireland.  They 
belong  to  the  Bronze  and  Stone  Ages,  affording  remains  of  various  living 
species  of  Mammals,  with  stone  implements  in  some  of  them. 

Examples  of  recent  relics  are  presented  in  Figs.  1569,  1570.  Fig.  1569 
represents  a  human  skeleton,  from  a  shell  limestone  of  modern  formation 
now  in  progress,  on  the  island  of  Guadaloupe.  The  specimen  is  in  the 
Museum  at  Paris.  The  British  Museum  contains  another  from  the  same 
region,  but  wanting  the  head,  which  is  in  the  collection  of  the  Medical 
College  at  Charleston  in  South  Carolina.  They  are  the  remains  of  Caribs, 
who  were  killed  in  a  fight  with  a  neighboring  tribe,  about  two  and  a  half 
centuries  since.  Fig.  1570  represents  another  fossil  specimen,  of  the  age 
of  Man,  —  a  ferruginous  conglomerate,  containing  silver  coins  of  the  reign 
of  Edward  I.  and  some  others,  found  at  Tutbury,  England.  It  was  obtained 
at  a  depth  of  ten  feet  below  the  bed  of  the  river  Dove. 

Among  the  species  recently  exterminated,  there  are  the  Moa  (Dinornis) 
and  other  birds  of  New  Zealand,  the  Dodo  (Didus  ineptus)  and  some  of  its 
associates  on  Mauritius  and  the  adjoining  islands  in  the  Indian  Ocean ;  the 
.^Epyornis  of  Madagascar.  The  species  are  of  the  half-fledged  kind,  like 
the  Ostrich.  Fig.  1571  (copied  from  Strickland's  Dodo  and  its  Kindred}  is 
from  a  painting  at  Vienna,  made  by  Roland  Savery  in  1628. 

The  Dodo  was  a  large,  clumsy  bird,  some  50  pounds  in  weight,  with  loose,  downy 
plumage,  and  wings  no  more  perfect  than  those  of  a  young  chicken.  The  Dutch  navigators 
found  it  on  Mauritius  in  great  numbers,  in  the  seventeenth  century.  But,  after  the  pos- 
session of  the  island  by  the  French,  in  1712,  nothing  more  is  heard  of  the  Dodo;  there 
are  some  pictures  in  the  works  of  the  Dutch  voyagers,  and  a  few  imperfect  remains. 

The  Solitaire  (Pezophaps  solitaria)  is  another  exterminated  bird,  of  the  same  island, 
and  the  Heron  (Nycticorax  megacephalus')  a  third  (Fig.  1571). 

The  Moa  (Dinornis  giganteus  Owen),  of  New  Zealand,  exceeded  the  Ostrich  in 
size,  being  10'  to  12'  in  height.  The  tibia  (drumstick)  of  the  bird  was  30  to  32  inches  in 
length;  and  the  eggs  so  large  that  "a  hat  would  make  a  good  eggcup  for  them."  The 
bones  were  found  along  with  charred  wood,  showing  that  the  birds  had  been  killed 
and  eaten  by  the  natives.  The  name  Dinornis  is  from  5eti/6s,  terrible,  and  8pvis,  bird. 
Eleven  other  species  of  Dinornis  have  been  found  on  New  Zealand. 

Besides  the  Dinornis  giganteus,  have  been  found  also  extinct  species  of  Palapteryx 
and  Notornis.  Palapteryx  is  related  to  Apteryx;  and  both  Apteryx  and  Notornis  have 
living  species. 

Besides  these,  there  are  other  related  extinct  New  Zealand  Birds,  pertaining  to  the 
genera  Anomalopteryx,  Pnesopteryx,  Syornis,  Euryapteryx,  and  others  (Hector,  1891). 

On  Madagascar,  other  species  of  this  family  of  gigantic  birds  formerly  existed. 
Three  species  have  been  made  out  of  the  genus  ^Epyornis.  From  the  bones  of  the  leg, 
one  is  supposed  to  have  been  at  least  12'  in  height.  The  egg  was  13|  inches  long. 

The  Drepanis  Pacifica,  or  Sickle-bill  of  the  Sandwich  Islands,  the  bird  used  in  making 
the  royal  robes,  is  now  extinct. 

The  Great  Auk  of  the  North  Sea  (Alca  impennis  Linn.)  is  reported  to  be  an  extinct 
bird,  by  Professor  Steenstrup.  The  last  known  to  have  been  seen  were  two  taken  near 


CENOZOIC    TIME  —  QUATERNARY. 


1015 


Iceland,  in  1844.  The  bones  occur  in  great  numbers,  on  the  shores  of  Iceland,  Greenland, 
and  Denmark,  showing  that  it  was  once  a  common  bird  ;  and  its  remains  have  been  found 
also  on  the  coasts  of  Labrador,  Maine,  and  eastern  Massachusetts.  They  occur  in  the 
shell-heaps  of  Maine,  Wyman  having  found  seven  specimens  of  the  humerus,  besides 
other  bones.  With  these  are  bones  of  other  species,  but  of  none  that  are  extinct,  and  also 
fragments  of  rude,  pottery,  and  some  bone-implements. 

1571 


Dodo,  with  the  Solitaire  in  the  background  and  an  extinct  Night  Heron  to  the  right. 

A  species  of  Manatee,  Eytina  Stelleri  Cuv.,  known  in  the  last  century  on  the  Arctic 
shores  of  Siberia,  is  supposed  to  be  now  extinct. 

The  Aurochs  (Bison  prisons')  of  Europe,  one  of  the  cotemporaries  of  the  old  Elephant 
(Elephas  primigenius')  1  would  have  long  since  been  exterminated  from  Europe,  but  for 
the  protection  of  Man.  Though  once  abundant,  it  is  now  confined  on  that  continent 


1016  HISTORICAL   GEOLOGY. 

to  the  imperial  forests  of  the  Kussian  Czar  in  Lithuania.  It  is  said  to  exist  also  in  the 
Caucasus.  The  now  extinct  Bos  primigenius  is  supposed  to  be  the  same  with  the  Urus 
(Ure-Ox,  or  Bos  Urus,  described  by  Csesar  in  his  Commentaries,  and  stated  to  abound 
in  the  Gallic  forests),  and  is  a  distinct  species  from  the  Aurochs,  with  which  it  has  been 
confounded.  It  is  said  to  have  continued  in  Switzerland  into  the  sixteenth  century. 

The  American  Buffalo  {Bos  Americanus  Gm.)  formerly  covered  the  eastern  part 
of  the  continent,  to  the  Atlantic,  and  extended  south  into  Florida,  Texas,  and  Mexico ; 
but  now  it  is  practically  an  extinct  species,  except  so  far  as  it  is  under  human  protection. 

The  giant  Sequoia  or  Kedwood  of  California  is  sure  to  become  extinct  as  a  native 
plant. 


GENERAL  OBSERVATIONS  ON  THE  QUATERNARY. 
BIOLOGICAL  PROGRESS. 

Culmination  of  the  type  of  Brute  Mammals.  —  The  biological  progress  of 
the  Quaternary  as  it  appears  in  Brute  Mammals  was  but  a  continuation  of 
the  types  of  the  Tertiary  onward  to  their  culmination  in  the  course  of  the 
Champlain  period.  The  great  average  size  of  the  species,  in  connection  with 
the  evidence  of  unimpaired  powers,  and  also  the  large  number  of  the  species 
as  well  as  the  dense  population,  are  good  evidence  that  Brute  Mammals  have 
passed  their  maximum  development.  More  than  half  of  the  species  that 
then  existed  are  probably  yet  unknown.  But  the  facts  are  sufficient,  never- 
theless, to  sustain  the  above  statement.  The  area  occupied  by  the  great 
Mammals  extends  from  Alaska  to  Patagonia,  from  Great  Britain,  and  the 
Siberian  shores,  to  southern  Australia.  A  species  best  thrives  in  the  region 
of  fittest  climate.  In  the  Pleistocene,  the  fittest  climate  was  universal. 
Geologists  have  attributed  the  extinction  of  most  of  the  species  and  the 
dwindling  of  others  to  the  cold  of  the  Reindeer  epoch.  It  is  the  only 
explanation  yet  found,  though  seemingly  insufficient  for  the  Americas. 

The  era  of  Fishes,  as  has  been  stated,  was  the  time  of  urosthenic  Verte- 
brates, species  in  which  the  posterior  extremity  of  the  body  serves  as  the 
locomotive  organ ;  and  the  era  of  Amphibians  and  Reptiles,  the  time  of 
merosthenic  Vertebrates,  the  hind  legs  of  the  species  being  the  stronger 
limbs  in  locomotion.  Under  the  era  of  Mammals  the  merosthenic  species 
comprise  the  Herbivores,  and  many  of  them  are  made  to  serve  Man  as 
draught-animals,  because  of  their  strong  hind  limbs ;  but  the  higher  Mam- 
mals, the  Carnivores  and  Quadrumana,  are  prosthenic,  the  anterior  limbs 
being  not  simply  locomotive  organs,  but  having  some  prehensile  power,  and 
in  the  most  of  the  species  eminently  serviceable  in  this  way.  Only  carniv- 
orous and  herbivorous  species  that  have  taken  to  a  water  life  are  urosthenic, 
and  this  they  have  become  by  returning  to  the  element  that  is  especially 
fitted  for  Fish-like  locomotion. 

Relation  of  the  Quaternary  to  the  Tertiary  Mammals.  —  The  Quaternary 
types  of  fauna  and  flora  on  a  continent  were  to  a  large  extent  closely  related 
in  kind  to  those  of  the  Tertiary.  South  America  in  Pleistocene  time  was 
prominently  the  land  of  Edentates ;  and  so,  during  the  Tertiary,  Edentates 


CENOZOIC    TIME  —  QUATERNARY.  1017 

were  common  species.  Australia  is  now  and  has  been  through  the  Quater- 
nary the  continent  of  Marsupials  and  Monotremes  ;  and  the  same  types  were 
almost  its  only  Mammalian  population  in  the  Tertiary.  North  America,  dis- 
tinguished for  its  large  number  of  Pleistocene  Herbivores  and  relatively  few 
•Carnivores,  was  equally  so  distinguished  during  the  Tertiary ;  while  Eurasia, 
in  both  the  Tertiary  and  Quaternary  eras,  was  the  chief  region  of  Carnivores. 
The  principle  could  be  illustrated  by  examples  from  tribes  and  species 
throughout  the  kingdoms  of  life  ;  but  this  would  be  out  of  place  here.  It  is 
(explained  by  Darwin  on  the  ground  that  the  Quaternary  kinds  have  been 
derived  from  the  Tertiary  by  descent ;  and  this  explanation  is  now  generally 
accepted.  The  exceptions  to  the  rule  have  come  chiefly  through  migration. 

Progress  in  degeneration.  —  The  most  prominent  cases  of  degeneracy  in 
terrestrial  Quaternary  Mammals  occur  in  the  Edentates.  A  great  popula- 
tion of  them  lived  in  South  America,  pertaining  to  numerous  genera  against 
two  in  Europe,  Asia,  and  Africa.  The  Glyptodonts  (Figs.  1563,  1564) 
appear  to  have  been  the  lowest.  The  thick  bony  covering  is  protective,  and 
very  completely  so.  It  is  Molluscan  in  idea.  From  what  higher  Mammals 
they  descended  is  not  known.  The  low-grade  characteristics  seem  to  be  a 
•consequence  of  inactive  habits  or  sluggishness  as  a  result  of  freedom  from 
-enemies  and  from  all  unsatisfied  desires.  Degeneracy  from  inactivity  is  well 
exemplified  in  parasitic  Crustaceans,  as  the  Lernseans,  which  live  with  the 
head-end  inside  of  a  fish,  always  content.  As  a  consequence  they  have 
become  worm-like  in  body,  and  almost  limbless  and  senseless.  There  is 
here,  emphatically,  degeneracy  through  disuse,  with  adaptations  to  the  con- 
ditions ;  their  origin  is  thus  explained  by  disuse  and  adaptation  without 
reference  to  the  "survival  of  the  fittest,"  or  "natural  selection."  The 
same  is  true  of  the  Megatheria;  their  legs  became  reduced  nearly  to  massive 
pedestals  by  inactivity,  and  the  front  teeth,  as  in  other  Edentates,  were  lost 
through  disuse.  The  Glyptodonts  degenerated  on  the  same  principle ;  but, 
through  some  organic  tendency  (like  that  less  perfectly  illustrated  in  the 
Turtles,  the  most  sluggish  of  Keptiles),  ossification  gave  them — and  emi- 
nently so  Doedicurus  —  a  protective  covering  almost  to  their  destruction. 
It  was  fitted  to  save  from  Carnivores,  but  not  from  the  cooler  climate  that 
ensued,  and  so  the  later  fauna  of  the  region  was  rid  of  them,  —  exemplifying 
the  fact  that  the  principle  of  the  "  survival  of  the  fittest "  determines  the 
species  that  survive  to  constitute  new  faunas,  if  not  the  existence  of  new 
species.  The  first  of  the  Glyptodonts  appeared  in  the  Miocene. 

Man.  —  Man  stands  in  the  successional  line  of  the  Quadrumana,  at  the 
head  of  the  Animal  Kingdom.  But  he  is  not  a  Primate  among  Primates. 
The  Quadrumana  are,  as  Cuvier  called  them,  Quadrumana  from  the  first  to 
the  last.  They  are  Brute  Mammals,  as  is  manifested  in  their  Carnivore-like 
canines  and  their  powerful  jaws ;  in  their  powerful  muscular  development ; 
in  their  walking  on  all  fours,  and  the  adaptation  thereto  exhibited  in  the 
vertebrae,  producing  the  convexity  of  the  back ;  and  also  in  other  parts  of  the 
skeleton. 


1018  HISTORICAL   GEOLOGY. 

Man,  on  the  contrary,  is  not  Quadrumanous.  His  limbs  are  of  the  primitive- 
type  so  common  in  the  Eocene.  He  is  plantigrade,  "  has  neither  hoofs  nor 
claws  to  his  five  toes  and  fingers,  but  something  between  the  two."  More- 
over, in  his  teeth  "  Man  is  thoroughly  primitive,  he  having  in  fact  the  original 
quadrituberculate  form  of  molar,  with  but  little  modification,"  and  also 
having  "  the  teeth  of  the  two  jaws  exactly  alike,  and  making  one  continuous 
even  series,  with  nothing  of  the  diastema  which  prevailed  among  the 
higher  Monkeys."  The  body  of  Man  has  retrograded  also  in  being 
merosthenic  in  limbs,  instead  of  prosthenic,  the  hinder  limbs  being  the 
stronger  as  well  as  longer,  and  the  fore  limbs  comparatively  weak.  All 
these  low-grade  characteristics  and  despecialized  conditions  of  the  structure 
evince  that  Man  does  not  pertain  zoologically  to  the  group  called  Primates, 
either  to  the  higher  or  lower  end  of  the  series.  Considering  further  the 
zoological  fact  that  Man  is  an  erect  Mammal,  and  the  only  erect  species- 
in  the  whole  series,  the  bones  throughout  the  structure,  with  the  double 
curvature  of  the  back,  being  adapted  to  this  characteristic ;  that  his  fore 
limbs  are  taken  from  the  locomotive  series  and  passed  over  to  the  cephalic, 
to  subserve  especially  the  purposes  of  the  brain;  that  muscular  power  is  not 
in  him  the  foundation  of  grade  and  efficiency,  but  that  he  has  a  brain  more 
than  twice  the  size  of  the  highest  of  the  Quadrumana,  and  herein  is  prosthenic 
to  a  preeminent  degree,  as  the  labors  of  his  hands  and  head  declare,  the 
divergence  from  the  Quadrumana  is  manifestly  great.  Man's  "  low-grade  " 
or  "  primitive  "  characteristics  have  special  fitness  for  the  exalted  being ;  and 
this  is  sufficient  reason  for  their  existence. 

Man,  moreover,  is  the  last  species  of  the  series.  Agassiz  observed  that 
the  Vertebrate  type,  which  began  during  the  Paleozoic  in  the  prone  or  hori- 
zontal Fish,  became  erect  in  Man,  and  thus  completed  the  possible  changes 
in  the  series,  to  its  last  term.  An  erect  body,  with  an  erect  forehead  and  a 
symmetry  that  is  of  ideal  perfection,  admits  of  no  step  beyond. 

Man  was  the  first  being,  in  the  geological  succession,  capable  of  an 
intelligent  survey  of  nature  and  a  comprehension  of  her  laws ;  the  first 
capable  of  augmenting  his  strength  by  bending  nature  to  his  service,  render- 
ing thereby  a  weak  body  stronger  than  all  possible  animal  force ;  the  first 
capable  of  deriving  happiness  from  truth  and  goodness ;  of  apprehending 
eternal  right ;  of  reaching  toward  a  knowledge  of  self  and  God ;  the  first, 
therefore,  capable  of  conscious  obedience  or  disobedience  of  a  moral  law, 
and  the  first  subject  to  debasement  of  his  moral  nature  through  his  appetites. 

There  is  in  Man,  therefore,  a  spiritual  element  in  which  the  brute  has 
no  share.  His  power  of  indefinite  progress,  his  thoughts  and  desires  that 
look  onward  even  beyond  time,  his  recognition  of  spiritual  existence  and  of 
a  Divinity  above,  all  evince  a  nature  that  partakes  of  the  infinite  and  divine. 
Man  is  linked  to  the  past  through  the  system  of  life,  of  which  he  is  the  last, 
the  completing,  creation.  But,  unlike  other  species  of  that  closing  system 
of  the  past,  he,  through  his  spiritual  nature,  is  more  intimately  connected 
with  the  opening  future. 


CENOZOIC    TIME  —  QUATERNARY.  1019* 


THE  ANTARCTIC   CONTINENT   IN  THE   QUATERNARY. 

The  Antarctic  Continent  appears  to  have  been  enlarged  during  the  Pleis- 
tocene to  the  wide  limits  it  had  in  Permian  time,  and  to  have  thus  renewed 
its  connection  with  southern  Africa,  Madagascar,  the  Mauritius  group  or 
Mascarene  Islands,  and  Australia,  and  probably  also  with  South  America. 
At  the  same  time,  Australia  was  enlarged  eastward  to  New  Zealand  and 
beyond  to  the  Chatham  Islands,  as  well  as  northward  along  the  islands  in 
the  New  Zealand  line;  or  else  it  derived  a  connection  with  these  islands 
through  extension  of  the  Antarctic  Continent.  As  shown  on  the  Bathymet- 
ric  chart,  following  page  20,  the  joining  of  Chatham  Island  to  New  Zealand 
would  require  an  elevation  of  only  800  feet ;  and  one  of  1200  would  unite 
northeastern  Australia  to  New  Caledonia ;  and  one  of  500,  Australia  to 
New  Guinea. 

The  evidence  of  these  connections  is  based  chiefly  on  the  near  identity  in 
some  species  of  Birds  and  other  animals  of  these  widely  distant  lands.  The 
genus  Aphanapteryx  (related  to  that  of  the  Rails),  known  for  some  years 
from  Mauritius  (east  of  Madagascar),  has  been  found  by  H.  0.  Forbes  to 
have  had  a  species  on  one  of  the  Chatham  Islands,  —  distant  from  Mauritius 
over  120°  in  latitude  ;  and  the  two  species,  A.  Brcecki  of  Mauritius,  and 
A.  Hawkinsii  of  the  Chatham  Islands,  are  scarcely  distinguishable.  Several 
species  of  New  Zealand  Birds  were  found  by  Forbes  on  Chatham  Island; 
among  them  the  Kea,  a  Parrot  "  that  changed  its  diet  in  recent  years,  for- 
saking fruits,  and  now  kills  sheep  by  eating  through  their  backs  to  their  vital 
organs  "  ;  the  flightless  Woodhen,  Ocydromus  Australia,  the  Owl,  Glaucidium 
Novi-Zealandice,  and  also  a  Hawk  and  Swan. 

Further,  Australia  had,  in  Quaternary  time,  a  Dromornis,  closely  related 
to  the  gigantic  Dinornis  of  New  Zealand  and  the  ^Epyornis  of  Madagascar. 
Moreover,  Africa  has  the  related  Ostrich ;  and  southern  South  America  has 
afforded  remains  of  a  great  flightless  bird  of  Ostrich  affinities.  The  Penguins, 
also  flightless  birds,  range  from  South  America  to  South  Africa,  Australia, 
New  Zealand,  and  the  Antarctic  Islands.  Similar  facts  occur  among  Eden- 
tates, Amphibians,  and  Plants. 

Forbes,  in  view  of  the  facts,  concludes  that  the  land  of  the  Antarctic 
circle  had,  in  late  geological  time,  a  large  extension,  admitting  of  migration 
between  the  continents  and  with  the  adjoining  or  adjoined  islands.  He 
remarks,  also,  on  the  glaciated  condition  of  such  a  continent  in  a  Glacial 
period,  and  its  effects  in  producing  cold  or  glacial  conditions  in  the  southern 
hemisphere. 

Forbes's  paper  is  contained  in  the  Proceedings  of  the  Geographical  Society 
of  London,  October,  1892,  and  in  the  Geological  Magazine  for  May,  1893 ; 
and  he  has  another  paper  on  the  subject  of  zoological  character  in  the  Maga- 
zine of  Natural  History,  July,  1893. 


1020  HISTORICAL   GEOLOGY. 


EPEIROGENIC  CHANGES  DURING  THE  QUATERNARY. 

The  upward  continental  movements  of  the  early  Quaternary  and  the  late 
Tertiary,  by  which  the  greater  mountain  regions  of  the  globe  were  elevated 
from  10,000  to  more  than  20,000  feet,  and,  following  this,  the  wide-reaching 
but  feeble  downward  movement  of  the  Middle  Quaternary,  and  then  the  more 
limited  elevation  closing  the  Champlain  period,  and,  last,  the  settling  back 
of  the  land  to  the  degree  of  equilibrium  characterizing  Recent  time,  brought 
gradually  and  grandly  to  an  end  the  earth's  mountain-making.  The  move- 
ments were  epeirogenic,  and  involved  the  whole  sphere.  It  has  been  thought 
incredible  that  the  orographic  climax  should  have  come  so  near  the  end  of 
geological  time,  instead  of  in  an  early  age,  when  the  crust  had  a  plastic  layer 
beneath,  and  was  free  to  move ;  yet  the  fact  is  beyond  question.  The  event 
is  made,  on  r>age  392,  a  legitimate  effect  of  lateral  pressure  in  the  contracting 
crust ;  and  the  coral-island  subsidence,  or,  in  more  general  language,  the 
deepening  of  great  areas  over  the  oceanic  basin,  is  set  forth  on  the  same 
page  as  the  counterpart. 

Why,  in  the  upward  movement,  the  colder  latitudes,  or  those  outside  of 
the  parallel  of  40°,  should  have  been  most  affected,  as  the  distribution  of 
fiords  and  other  facts  make  evident,  is  wholly  unexplained.  The  interest 
•of  the  problem  is  greatly  enhanced  by  the  new  facts  proving  that  the  Ant- 
arctic Continent  also  was  elevated  and  greatly  enlarged,  —  probably  to  four 
times  its  present  area;  that  not  only  the  lands  of  the  high  northern  lati- 
tudes were  affected,  but  also  their  antipodes  in  the  high  southern  latitudes. 
Under  these  conditions  the  earth's  polar  diameter  would  have  received  a 
considerable  increase  of  length,  and  the  waters  would  have  been  deepened 
over  the  lower  latitudes. 

The  idea  of  Croll,  that  the  Glacial  periods  of  the  northern  and  southern 
hemispheres  followed  one  another,  has  no  support  from  geological  facts,  and 
few  supporters  among  geologists. 

The  Champlain  subsidence  following  the  elevation  has  been  attributed, 
•on  the  principle  of  isostasy,  as  stated  on  page  379,  to  the  weight  of  the 
load  of  ice  over  the  glaciated  land.  The  cause  is  good  in  principle,  but 
•of  doubtful  sufficiency.  The  facts  stated  on  page  980,  with  regard  to  the 
departure  of  the  ice  from  the  United  States  before  the  subsidence  had  made 
much  progress,  indicate  a  great  lagging  in  the  effect,  far  greater  than  is  com- 
patible with  the  results  of  a  load.  Moreover,  the  coast  region  of  California 
.subsided  deeply  (page  985)  although  it  had  not  been  covered  by  ice;  and 
the  land  which  joined  South  America  with  Cuba  and  probably  Florida,  and 
that  uniting  Africa  to  Malta  and  Sicily  disappeared,  although  far  outside 
of  the  ice-limit.  The  dry  land  across  the  British  Channel  between  England 
.and  France  continued  emerged  long  after  the  mild  climate,  which  favored 
migration  of  warm  climate  Mammals,  set  in;  and  it  became  submerged 
although  the  land  either  side  was  never  under  the  ice-sheet.  France  and 


CENOZOIC   TIME  —  QUATERNARY.  1021 

other  parts  of  Europe  bear  evidence  of  subsidence  in  the  many  terraced 
river  valleys  and  sea  borders,  although  never  glaciated.  Other  facts  bear- 
ing on  the  question  will  be  found  in  a  recent  paper  by  Prestwich  on  the 
late  Post-glacial  submergence.  The  ice  of  the  locally  glaciated  areas  over 
Europe  could  have  depressed  isostatically  only  equal  areas  to  a  depth  less 
than  two  fifths  of  the  mean  thickness  of  the  ice. 

The  insufficiency  of  the  ice-sheet  to  produce  the  widely  extended  Cham- 
plain  submergence  is  evident.  The  only  other .  agency  to  which  appeal  has 
been  made  is  that  of  the  earth's  contraction;  this  makes  the  movements  of 
the  Quaternary  one  in  cause  and  system. 

The  Recent  period  has  its  epeirogenic  movements  partly  as  a  continuation 
of  the  earlier,  and  partly  as  a  result,  it  is  believed,  of  the  deposition  along 
coasts  and  elsewhere  of  river  sediment.  The  principal  facts  have  been 
reviewed  on  pages  341,  367.  Another  example,  of  a  geanticlinal  character, 
is  afforded  by  the  Scandinavian  region.  A  recent  report  on  the  subject  has 
been  made  by  L.  Holmstrom  (1888).  On  the  west  coast,  at  two  localities, 
in  latitudes  57°  53'  K  and  58°  56'  N.,  the  rate  of  rise  of  the  land,  during 
respectively  66  and  116  years  before  1886,  was  about  two  inches  in  ten  years ; 
and  at  another  place,  in  58°  35'  N.,  about  four  inches  in  ten  years.  On  the 
east  coast,  at  several  localities  between  58°  45'  N.  and  65°  15'  N.,  the  rate 
during  various  intervals  from  45  to  139  years  before  1867  to  1875,  was  1-8 
to  four  inches  in  ten  years;  at  Stockholm,  1-85  inches;  and  in  Finland,  in 
63°  N.,  2-5  to  3'75  inches.  The  rise  is  least  to  the  south.  The  conclusions 
differ  but  little  from  those  derived  by  Lyell  from  the  facts  he  gathered, 
during  his  visit  to  the  coast  in  1834. 

Moreover,  the  many  fault  planes  in  the  earth's  crust  resulting  from  old 
erogenic  movements  are  planes  of  weakness,  and  show  it  from  time  to  time 
by  slips  and  consequent  earthquakes  (p:ige  373).  It  is  rendered  probable 
that  regions  over  the  Rocky  Mountains  may  still  be  in  slow  movement  up 
or  down. 

Upturned  beds  occur  on  all  the  islands  south  of  New  England  from  Long  Island  to 
Nantucket.  But  although  the  disturbance  has  been  supposed  to  be  of  Quaternary  origin, 
the  chief  part  is  of  earlier  date.  The  beds  of  Long  Island  were  first  described  by  W.  W. 
Mather  in  his  excellent  account  of  Long  Island  geology  contained  in  his  New  York  Geo- 
logical Report  (in  quarto)  of  1843. 

The  deposits,  as  made  by  Mather  and  as  has  since  been  proved  by  fossils,  are  Creta- 
ceous clays,  sand  and  pebble  beds  with  overlying  Quaternary  drift.  The  bluffs  of  150  to 
200  feet  along  the  northern  coast  have  the  beds  mostly  concealed  by  the  fallen  debris 
from  above.  But  part  of  Mather's  investigations -were  made  after  a  "storm  of  the  llth 
and  12th  of  October,  1836,"  when  the  cliffs  were  laid  bare,  giving  him  an  unusual  oppor- 
tunity for  the  study  of  the  stratification.  He  was  led  to  the  conclusion  that  the  flexures 
are  partly  local  displacements  in  the  clay-beds,  due  to  vertical  pressure  and  slides,  and 
partly  a  result  of  upturnings  anterior  to  the  drift  deposits.  This  accords  with  the  author's 
observations  over  the  island.  It  sets  aside  the  idea  that  the  flexures  were  in  any  case  an 
effect  of  pressure  from  the  moving  ice-sheet. 

Figs.  1572  to  1575  are  from  Plate  iv.  in  Mather's  Report.  The  cramplings  in  Figs. 
1572  and  1573  are  like  those  that  are  made  by  local  pressure  or  slides,  or  sinkings  of  the 


1022 


HISTORICAL   GEOLOGY. 


overlying  beds,  which  shoved  aside  and  forced  out  the  wet  and  mobile  clay.  At  many 
places  along  the  coast  the  clay  has  been  forced  out  in  this  way  and  now  covers  more  or 
less  of  the  slope  below ;  and  in  the  clay -pits,  sinking  and  exclusions  are  not  uncommon. 
At  the  Holmes  clay-pit  on  Fresh  Pond,  near  Northport,  there  were  cracks  in  1875  at  the 
top  of  the  bluff  where  the  sinking  was  in  progress,  and  where,  as  the  proprietor  stated, 
it  had  amounted  to  16  inches  in  20  months,  and  the  movement,  he  added,  was  all  the  time 
going  on.  A  clay -bed  is  made  to  vary  greatly  in  thickness  in  the  face  of  a  bluff  because 
locally  squeezed  out. 


1572 


1572-1575. 
1573 


15T4 


Sections  of  the  Cretaceous  and  overlying  beds  on  the  north  side  of  Long  Island.  Figs.  1572,  1573,  Sections  near 
Brown's  Point,  Petty's  Bight ;  1574,  Section  3£  miles  south  of  Oyster  Point ;  1575,  Section  exposed  by  a  storm 
200  yards  south  of  Brown's  Point.  W.  W.  Mather. 

In  the  case  represented  by  Fig.  1575,  the  position  of  the  beds  plainly  proves,  as  Mather 
states  (page  249) ,  that  an  upturning  and  a  subsequent  denudation  had  taken  place  after 
the  lower  beds  of  alternating  clay  and  sand  had  been  formed,  and  before  the  deposition 
of  the  overlying  clay-bed  and  the  higher  deposit  of  "coarse  materials  and  bowlders"  or 
drift.  The  tilting  in  Figs.  1572-1574  probably  had  the  same  origin.  The  age  of  the  clay- 
bed  C.  I.  in  Fig.  1575  is  left  uncertain ;  but  the  upturned  beds  are  Cretaceous.  Mather 
states  that  in  all  sections  the  overlying  drift  deposits  have  the  same  horizontal  position, 
and  that  some  of  the  bowlders  contained  in  them  have  great  size.  "Blocks  of  50  to  500 
tons  are  not  uncommon  on  the  island"  (page  174);  and  he  reports  one  having  an  esti- 
mated weight  of  2000  tons. 

The  upturned  beds  in  Desor's  Nantucket  section,  referred  to  on  page  983,  are  covered 
by  others  in  horizontal  position,  and  are  probably  of  the  same  age  and  origin  with  those 
of  Long  Island. 

On  Martha's  Vineyard,  according  to  Shaler,  the  upturned  beds,  which  include  the 
Cretaceous  and  Tertiary,  bear  evidence  in  their  erosion  that  the  chief  upturning  preceded 
the  Later  Glacial  epoch,  if  not  partly  at  least  the  earlier.  Lyell,  in  his  Travels  in  North 
America  (1845),  describes  the  sections  at  Gay  Head  and  Chilmark,  figures  the  former 
(i,  204),  and  states  that  the  upturning  occurred  between  the  Miocene  Tertiary  and  the 
"  Boulder  "  or  Drift  period. 


There  is  grandeur  in  the  simplicity  as  well  as  vastness  of  the  movements 
by  which  the  earth  was  made  ready  for  its  latest  stage.     Equally  simple  and 


GENERAL   OBSERVATIONS.  1023 

comprehensive  were  the  agencies  set  to  work :  glaciers  that  reached  across 
from  ocean  to  ocean ;  rivers  deriving  magnitude  and  energy  from  the  loftiest 
of  mountains,  the  greatest  of  ice-sheets  and  the  most  abundant  of  rains; 
and  a  genial  climate  that  reached  almost  to  polar  latitudes,  and  produced 
luxuriant  growth  in  all  life,  animal  as  well  as  vegetable.  Thus  were  evolved, 
as  never  before,  the  sublimity  of  the  mountain  peaks,  and  the  richness  and 
varied  beauty  of  the  valleys  and  wide-reaching  plains,  and  the  many  other 
surface  details  that  were  essential  to  the  pastoral  and  agricultural  pursuits 
with  which  man  was  to  commence  his  own  development. 


GENERAL   OBSERVATIONS   ON   GEOLOGICAL   HISTORY. 
LENGTH  OF  GEOLOGICAL   TIME. 

Time-ratios.  —  In  the  preceding  edition  of  this  work  estimates  are  given 
of  the  relative  lengths  of  the  ages  and  periods,  or  their  time-ratios,  based  on 
the  maximum  thicknesses  of  the  rock  formations  of  the  several  periods, 
allowing  a  ratio  of  1  to  5  between  the  rate  for  limestone  and  that  for  ordi- 
nary fragmental  rocks.  These  thicknesses  have  since  been  increased  much 
for  some  parts  of  the  geological  column ;  but  the  increase  is  not  far  from 
proportional  to  the  former  numbers.  The  evidence  at  present  obtained  ap- 
pears to  favor  the  conclusion  that  the  relative  duration  of  the  Cambrian  and 
Silurian,  the  Devonian  and  the  Carboniferous  eras,  corresponds  to  the  ratio 
41  :  1  :  1,  or  perhaps  4:1:1,  the  ratio  hitherto  adopted ;  and  for  the  Paleo- 
zoic, Mesozoic,  and  Cenozoic,  12  :  3  :  1.  The  thickness  of  upturned  rocks 
is  so  difficult  to  obtain  with  accuracy,  and  is  so  certainly  exaggerated 
greatly  when  the  absence  of  faults  and  flexures  is  not  ascertained  before 
drawing  conclusions,  especially  in  connection  with  the  older  tilted  forma- 
tions, that  much  careful  geological  work  is  yet  to  be  done  before  reliable 
ratios  can  be  deduced.  « 

Length  of  time  since  the  Glacial  period.  —  The  facts  with  regard  to  the 
present  rate  of  recession  of  Niagara  Falls  have  been  used  for  calculating  the 
length  of  time  since  the  Glacial  period.  The  argument  has  been  presented 
thus.  Niagara  has  made  its  present  gorge  by  a  slow  process  of  excavation, 
and  is  still  prolonging  it  toward  Lake  Erie.  Near  the  fall,  the  gorge  is  200 
to  250  feet  deep,  and  160  feet  at  the  fall,  — the  lower  80  feet  shale,  the  upper 
80  limestone.  The  waters  wear  out  the  shale,  and  thus  undermine  the  lime- 
stone. The  rocks  dip  15  feet  in  a  mile  up  stream,  so  that  the  limestone  at 
the  fall  becomes  thicker,  as  retrocession  goes  on.  The  distance  from  Niagara 
to  the  Queenston  Heights,  which  face  the  plain  bordering  Lake  Ontario,  is 
seven  miles.  The  general  features  of  the  region  are  shown  in  the  bird's-eye 
view,  page  973.  The  new  excavation  began  again  at  the  Queenston  Heights, 
and  gradually  extended  southward  to  its  present  limit  at  the  Falls.  The 
time  of  beginning  was  after  the  filling  of  the  channel  with  drift,  which 
occurred  during  the  retreat  of  the  glacier.  The  rate  of  progress  in  the  exca- 


1024  HISTORICAL  GEOLOGY. 

vation  was  estimated  by  R.  Bakewell,  Jr.  (son  of  the  English  geologist),  in 
1829,  on  the  basis  of  facts  received  from  a  40-years'  resident.  His  estimate 
was  about  three  feet  a  year.  Lyell,  who  was  at  the  Falls  in  1841  with 
James  Hall,  reduced  the  rate  to  one  foot  a  year,  making  the  elapsed  time 
about  31,000  years. 

The  question  has  since  been  considered  by  other  geologists.  G.  K.  Gilbert, 
taking  as  data  (1)  a  map  made  in  1842,  after  a  careful  survey  by  Blackwell 
in  1841,  and  published  in  the  K  Y.  Geological  Report  of  J.  Hall  (1842), 
(2)  another,  made  33  years  later,  by  the  U.  S.  Army  Engineers,  and  (3)  a 
third,  made  in  1886  by  R.  S.  Woodward,  concluded  that  the  rate  of  cutting, 
supposing  the  conditions  to  have  been  uniform,  was  about  five  feet  a  year, 
and  the  length  of  time  about  7000  years;  but  he  observes,  that  instead  of 
uniform  conditions,  there  have  been  great  variations  in  the  height  of  the 
fall,  and  in  the  amount  of  water,  and  that  the  deduced  rate  cannot  be  safely 
accepted  (Ann.  Rep.  Smithsonian  Inst.  for  1890). 

That  the  investigation  is  beset  with  doubt  is  evident  from  the  remarks 
on  page  987,  and  alsoxby  the  various  conclusions  of  recent  writers  on  the 
subject.  W.  Upham,  on  the  grounds  stated  in  his  various  papers,  makes, 
the  time  6000  to  10,000  years.  J.  W.  Spencer,  in  his  latest  interpretation 
of  the  facts  (1894),  arrives  at  the  conclusion  that  the  excavation  of  the 
channel  required  32,000  years.  But,  as  already  shown,  the  amount  of  water 
now  discharged  by  the  river  is  no  measure  of  that  during  the  Champlain 
period  of  moist  climate  and  expanded  but  gradually  diminishing  lakes,  and 
no  other  safe  basis  for  an  estimate  is  known.  As  the  amount  of  water  then 
was  almost  certainly  much  larger  than  now,  the  lower  estimates  are  probably 
nearest  the  truth. 

A  similar  estimate  has  been  made  by  K  H.  Winchell  (Final  Rep.  Geol. 
Minnesota)  for  the  rate  of  recession  of  the  Falls  of  St.  Anthony  on  the 
Mississippi  at  Minneapolis  (page  973),  with  the  result  that  the  elapsed  time 
was  probably  about  8000  years.  •• 

The  rate  of  progress  in  a  peat-bed,  and  that  in  a  thickening  deposit  of 
stalagmite  in  limestone  caverns,  are  other  uncertain  data  that  have  been 
employed  for  deducing  the  length  of  time  since  the  Glacial  period.  The 
amount  of  stalagmite  is  dependent  on  the  amount  of  carbonic  acid  or  organic 
acids  in  the  filtrating  waters,  and  partly  on  the  texture  of  the  limestone.  The 
results  of  such  calculations  do  not  appear  to  have  any  geological  or  archaeo- 
logical value. 

Length  of  geological  time  according  to  geological  evidence. — The  facts  from 
geology  used  as  a  basis  for  calculating  the  length  of  geological  time  since 
the  Archaean  are :  the  rate  of  sedimentation  or  accumulation,  and  the  rate  of 
erosion  or  denudation,  the  former  usually  made  dependent  on  the  latter. 
The  rate  of  denudation  is  generally  based  on  the  results  obtained  by 
Humphreys  and  Abbot  from  the  Mississippi  arid  its  drainage  area,  and 
related  results  from  the  study  of  other  rivers.  The  rate  of  sedimentation 
obtained  from  the  Mississippi  gives  an  average  of  one  foot  from  the  whole 


GENERAL,   OBSERVATIONS.  1025 

drainage  area  in  about  6000  years.  The  rate  usually  taken  is  one  foot  in 
3000  to  7000  years.  The  rate  1  to  3000  was  deduced  by  S.  Haughton  (1880) 
from  the  rate  of  sedimentation  of  the  following  rivers :  the  Mississippi,  6000 
years ;  Ganges,  2358  ;  Hoang  Ho,  1464 ;  Yang-tse-Kiang,  2700 ;  Ehone,  1526 ; 
Danube,  6846 ;  Po,  729  years ;  the  mean  of  which  is  3090  years.  He  adds 
that  since  the  sea  bottoms  are  to  the  land  surfaces  as  145  to  52,  the  rate  at 
which  the  sea  bottoms  are  becoming  silted  up,  that  is  to  say  the  present  rate 
of  formation  of  strata,  is  one  foot  in  8616  years.  Thence,  supposing  the  rate 
the  same  as  now  for  all  past  time  from  the  Archaean  onward,  the  whole 
duration  of  geological  time  is  200,000,000  years.  But  Haughton  included  in 
the  thickness  of  the  terranes,  60,750  feet  of  Archaean,  or  over  one  third  of 
his  total  (177,200  feet).  Deducting  for  the  Archaean,  the  length  of  the  rest 
of  geological  time  would  be  about  130,000,000  years. 

Mellard  Reade  makes  the  time  since  the  Archaean,  on  the  same  kind  of 
basis  (taking  the  mean  area  of  denudation  as  one  third  the  entire  land  area, 
and  the  rate  of  denudation  one  foot  in  3000  years),  95,000,000  years  (1893). 

C.  D.  Walcott  deduces,  for  the  elapsed  time,  70,000,000  years  (1893)  ; 
H.  H.  Hutchinson,  600,000,000  years  (1892) ;  M'Gee,  including  in  his  basis 
the  rate  of  denudation  at  Niagara,  and  giving  credit  to  the  extreme  estimates 
of  thickness  of  the  early  Paleozoic  formations,  6,000,000,000  years  (1893). 

All  these  estimates  proceed  on  the  solid  basis  of  existing  facts.  Yet  in 
deriving  them  the  extreme  difference  between  the  existing  earth  and  that  of 
the  geological  past  was  not  taken  into  account.  Going  back  in  geological 
time,  the  rock-making  portion  becomes  more  and  more  widely  marine,  and 
rivers  have  correspondingly  diminished  size  and  drainage  areas.  But,  at 
the  same  time,  climates  become  warmer  and  precipitation  therefore  increas- 
ingly abundant ;  and  through  Paleozoic  to  earlier  time  the  eroding  carbonic 
acid  and  oxygen  of  the  atmosphere  are  increased  in  amount,  and  corro- 
sion thereby  was  proportionately  greater.  Even  as  late  as  the  Middle 
Cretaceous,  the  western  half  of  North  America  was  an  open  sea  with  its 
large  and  small  islands.  In  the  Paleozoic,  and  still  more  in  the  Archaean, 
the  whole  continent  was  in  a  like  condition;  and  the  Continental  seas  had 
only  little  streams  and  drainage  areas  to  supply  sediment  for  the  thick 
formations,  so  that  the  sea  did  much  more  than  half  the  work  in  its  slow 
way.  Further,  changing  climates  have  occasioned  changing  rates  of  erosion 
and  sedimentary  deposition ;  and  have  made,  over  large  continental  areas, 
times  of  great  precipitation  to  alternate  with  times  of  prevailing  drought, 
and  times  of  full  lakes  and  of  large  hard-working  rivers,  with  times  of 
dwindled  or  feeble  waters.  In  addition,  the  deposits  of  one  period  have 
often  been  largely  denuded  to  make  those  of  the  following ;  and  the  chief 
sources  of  all  sediments  are  Archaean.  Attempts  therefore  to  find,  in  the 
results  of  aqueous  action,  a  definite  measure  of  any  part  of  the  geological 
past  necessarily  lead  to  very  doubtful  results. 

Length  of  geological  time  on  evidence  from  terrestrial  physics.  —  Kelvin 
pointed  out  in  1862  that  a  limit  to  the  earth's  age  is  fixed  by  the  known 
DANA'S  MANUAL  — 65 


1026  HISTORICAL   GEOLOGY. 

facts  as  to  the  rate  of  downward  increase  of  heat  and  the  rate  of  loss  of  heat 
into  space;  that  if  the  earth  had  cooled  less  than  20,000,000  years  since, 
the  internal  heat  would  have  been  greater  than  now ;  and  if  more  than 
400,000,000  years,  there  would  have  been  no  sensible  increase  of  heat  down- 
ward ;  and  he  suggested  a  probable  length  of  100,000,000  years.  The  bearing 
of  the  facts  as. to  tidal  retardation,  and  his  hypothesis  with  reference  to  the 
origin  and  age  of  the  sun's  heat,  gave  him  other  arguments  on  the  question ; 
but  the  conclusions  are  less  well  based  than  that  from  rate  of  cooling. 

Tait,  arguing  from  the  effect  of  tidal  retardation  on  the  figure  of  the 
earth  and  the  rate  of  cooling,  concluded,  that  the  time  which  can  be  allowed 
to  geologists  is  something  less  than  10,000,000  years ;  and,  in  view  of  the 
supposed  origin  of  the  sun's  heat  (by  the  falling  together  of  masses  of 
matter),  that  the  time  the  sun  has  been  illuminating  the  earth  is  not  more 
than  about  15,000,000  or  20,000,000  years ;  and,  again,  that  the  supposed 
concussion  would  have  made  heat  enough  to  last  the  earth  100,000,000  years. 
Croll  has  some  speculations  on  this  subject  in  Chapter  xxi.  of  his  Climate 
and  Time. 

Newcomb  says :  "  If  we  reflect  that  a  diminution  of  the  solar  heat  by 
less  than  one  fourth  its  amount  would  probably  mean  an  earth  so  cold  that 
all  the  water  on  its  surface  would  freeze,  while  an  increase  of  much  more 
than  one  half  would  probably  boil  all  the  water  away,  it  must  be  admitted 
that  the  balance  of  cause  which  would  result  in  the  sun  radiating  heat  just 
fast  enough  to  preserve  the  earth  in  its  present  state  has  probably  not 
existed  more  than  10,000,000  years." 

The  first  of  Kelvin's  methods  mentioned  above  has  been  adopted  by 
C.  King  (Am.  Jour.  Sc.,  1893),  with  new  data,  derived  from  experiments  by 
C.  Barus,  with  regard  to  the  latent  heat  of  fusion  of  the  rock  diabase,  its 
specific  heat  when  melted  and  when  solid,  and  its  volume  expansion  between 
the  solid  and  melted  state,  besides  other  points  bearing  on  the  subject.  The 
conclusion  reached  is  that  the  earth's  age  is  probably  24,000,000  years. 

The  safe  conclusion  from  all  the  Geological  and  Physical  facts  is  that 
Time  is  long,  very  long ;  long  enough  for  the  development  of  all  the  earth's 
rocks,  mountains,  continents,  and  life.  Geologists  have  no  reason  to  feel 
hampered  in  their  speculations,  while  the  extreme  results  of  calculation  are 
10,000,000  and  6,000,000,000  years. 

CLIMATAL  DEVELOPMENT. 

A  globe  that  has  slowly  cooled  from  fusion,  and  has  had  in  the  past, 
as  now,  a  sun  that  is  losing  heat  like  itself,  must  have  been  a  globe  also  of 
cooling  climates.  But  its  orbit  has  wide  variations,  and  the  sun,  it  is 
supposed,  its  varying  phases.  Moreover,  the  present  era  is  a  time  of  mild 
climate  compared  with  that  of  the  Glacial  period  which  preceded  it;  and 
hence  the  cooling  of  the  climates  has  not  been  continuous  and  regular,  but 
one  by  oscillations,  in  which  refrigeration  was  real,  though  often  passing 
through  extremes  in  both  directions. 


GENERAL   OBSERVATIONS.  1027 

Yet,  notwithstanding  these  sources  of  change,  no  good  evidence  in  all 
Paleozoic  time,  except  near  or  at  its  end,  has  been  found  in  the  fossils  or 
the  rocks,  of  zones  in  the  earth's  climates  or  of  variations  in  temperature. 
North  America  shows  in  its  large  coal  formation,  as  compared  with  that  of 
Europe,  that  it  had  then,  as  it  has  now,  the  moister  climate ;  and  therefore 
that  the  system  of  winds  was  the  same  as  in  Recent  time,  and  hence  that 
the  system  of  oceanic  currents  was  the  same.  Some  difference  must  have 
existed,  and  more  in  the  atmosphere  than  in  the  waters ;  but  it  was  not 
enough  to  modify,  as  far  as  has  been  ascertained,  the  marine  fauna  of  the 
globe.  Uniformity  in  climate  in  the  northern  hemisphere  is  favored  by 
unobstructed  oceanic  currents. 

In  the  later  part  of  the  Permian,  or  at  its  close,  a  cold  epoch  occurred 
(page  737).  At  the  same  time  happened  one  of  the  earth's  most  general 
exterminations  of  life.  But  large  continental  areas  were  then  rising,  and 
the  Antarctic  Continent  was  elevated  and  greatly  extended;  so  that  the 
elevations  may  have  been  the  cause  of  the  cold. 

After  the  close  of  Paleozoic  time,  zones  become  apparent  (page  791). 
But  even  in  the  earlier  part  of  the  Cretaceous  period,  Cycads  abounded 
in  the  northern  polar  regions,  showing  only  a  small  decline  in  mean  tem- 
perature since  the  Cambrian.  After  the  Middle  Cretaceous,  a  more  rapid 
decline  began  (page  872) ;  but,  concordantly,  large  continental  elevations 
were  in  progress.  The  increasing  elevations  during  the  later  Tertiary  cul- 
minated in  the  Glacial  period  of  the  Quaternary. 

Thus,  throughout  the  earth's  history  since  life  began,  the  only  cold 
epochs  of  which  proof  has  been  found  occurred  near  or  at  the  close  of  the 
Permian,  at  the  close  of  the  Triassic,  and  during  the  Glacial  period.  At  the 
close  of  the  Cretaceous,  another  epoch  is  suspected  to  have  occurred,  but 
without  direct  evidence. 

The  post-Permian  and  Glacial  cold  occurred  at  times  when  the  Antarctic 
Continent  had  great  extent,  and  therefore  when  the  earth's  polar  diameter 
had  unusual  elongation.  Since  the  Glacial  period,  the  polar  lands  have 
again  become  submerged ;  but,  inasmuch  as  Greenland  affords  evidence  of 
continued  subsidence,  it  may  be  questioned  whether  a  time  of  minimum  for 
the  polar  diameter  is  yet  reached. 

This  review  of  the  extremely  slow  decline  of  temperature  in  the  earth's 
climates  during  its  lifetime,  —  be  it  10  millions  of  years  or  600  times  this,  — 
with  traces  of  only  three  or  four  epochs  of  cold  in  the  course  of  the  millions, 
is  calculated  to  give  the  impression  that  the  eccentricity  cycle  in  the  earth's 
orbit  is  a  very  ineffectual  epoch-making  agency. 

THE  EARTH'S  DEVELOPMENT. 

The  evolution  of  the  earth's  continents  and  their  surface  features  is  one 
of  the  two  great  subjects  in  the  science  of  Geology.  The  idea  —  Continents 
always  Continents  —  announced  by  the  author  first  in  1846,  has  been  affirmed 


1028  HISTORICAL   GEOLOGY. 

by  all  that  has  since  come  to  light,  and  Geology  now  has,  as  regards  North 
America,  a  record  of  the  chief  consecutive  events  in  a  continuous  process  of 
development.  It  has  become  manifest  also  that  the  development  has  gone 
forward  not  simply  by  enlargement  about  a  nucleus,  but  through  successive 
stages  of  work  in  Interior  seas,  having,  in  general,  Archaean  confines ;  and 
that  the  great  Interior  Continental  sea  was  not  due  to  a  return  to  oceanic 
conditions,  but  a  phase  in  this  endogenous  feature  in  the  method  of  progress. 
Europe  also  had  its  interior  seas,  and  Asia, — the  two  almost  one;  and  so 
also  had  Australia,  for  the  later  facts  show  that  in  Cretaceous,  or  Cretaceous 
and  Tertiary  time,  the  Australian  continent  was  divided  in  two  by  such  interior 
waters.  An  exception  to  the  general  principle  has  been  made  by  putting  a 
hypothetical  continent  in  the  Indian  Ocean.  But  the  facts  suggesting  the 
hypothesis  have  been  shown  to  be  explained  otherwise. 

A  detailed  review,  in  this  place,  of  the  steps  in  the  process  of  develop- 
ment is  not  necessary.  The  closing  pages  of  the  Dynamical  Geology,  391 
to  396,  are  an  appropriate  continuation  of  these  remarks  on  the  earth's 
development.  With  regard  to  the  hypothesis  on  page  396,  respecting  the 
alternate  or  zigzag  arrangement  of  the  continents,  geological  history  affords 
no  satisfactory  testimony.  There  is  only  the  interesting  fact  that  the  ore 
belt  along  the  Andes  of  South  America  is  continued  through  the  nearly  east 
and  west  bend  of  Central  America  to  the  Kocky  Mountains  and  extends  on 
northward  to  Wyoming,  with  remarkable  similarity  in  its  ores  and  the  age 
of  the  veins.  Whether  the  supposed  continental  displacement  gave  this 
displacement  to  the  deep-seated  ore  region  that  in  the  earth's  later  eruptive 
periods  supplied  the  ore ;  or  whether  the  similar  position  of  the  ore  veins 
was  due  simply  to  a  like  position  of  the  two  continents  with  reference  to 
the  Pacific  oceanic  basin,  it  is  not  safe  to  say. 

Details  with  regard  to  continental  development  have  been  given  in  the 
chapters  on  Geographical  and  Geological  progress,  closing  the  accounts  of  the 
Lower  Silurian  (page  524),  the  Paleozoic  (page  714),  the  Mesozoic  (page 
867),  and  the  Tertiary  (page  932). 


PROGRESS  IN  THE  EARTH'S  LIFE. 

General  principles  with  regard  to  the  progress  in  the  earths  life.  —  The 
Animal  and  Vegetable  Kingdoms  studied  by  science  comprised,  not  very 
long  since,  only  living  species.  Through  the  revelations  of  geology  they 
now  include,  in  addition,  the  life  of  an  indefinite  succession  of  faunas, 
through  the  past  ages  up  to,  if  not  over,  the  borders  of  Archaean  time.  As 
a  consequence  of  these  developments,  the  following  principles  were  early 
announced  with  respect  to  the  progress  in  the  earth's  life :  — 

I.  Progress  from  aquatic  life  to  terrestrial  life,  commencing  in  the  waters- 
in  an  era  of  nearly  universal  waters,  and  reaching  its  higher  stages  over  the 
land. 


GENERAL   OBSERVATIONS.  1029 

IT.  Progress  from  the  simple  to  the  complex  or  the  more  specialized; 
animal  life,  commencing  with  Protozoans,  the  simplest  of  species,  without 
.special  organs  of  any  kind  —  Radiolarians,  the  minute,  silica-secreting, 
Khizopod-like  kinds,  having  been  reported  (1894)  from  rocks  of  Archaean 
time  —  and  becoming  displayed  in  a  few  comprehensive  structural  types, 
the  simpler  forms  of  which  appeared  in  early  time,  and  the  more  complex 
successively  afterward ;  the  new  organs  required  in  the  highest  manifesta- 
tions of  a  type  being  only  developments  through  modification  of  the  older, 
or  better  appliances  evolved  from  the  structure  for  carrying  forward  old 
processes. 

III.  The  succession  under  a  type  parallel  to  some  extent  with  the  embry- 
onic stages  in  related  living  species,  part  of  the  early  life  of  the  globe  repre- 
senting in  some  points  the  embryonic  or  young  life  of  to-day. 

IV.  Early  types,  often  a  combination  of  two  or  more  types  that  were 
afterward  differentiated,  that  is,  became  separate,  independent  branches  in 
the  sj^stem;  synthetic  types  of  Agassiz,  comprehensive  and  generalized  types 
of  others. 

V.  The  earlier  species  under  a  type  often  multiplicate  in  structure,  and 
losing  this  feature  with  rise  in  grade  (pages  421,  437,  486). 

VI.  The  culmination  of  types,  followed  by  degeneration,  and  often  ex- 
tinction, at  various  times  along  the  successive  eras. 

VII.  In  the  degeneration  of  a  type,  often  a  partial  return  to  some  of  its 
early  characteristics. 

VIII.  The  Animal  kingdom,  one  in  system  from  the  beginning, — the 
grander  divisions  of  modern  time  being,  to  a  large  extent,  those  of  the  ear- 
liest Paleozoic   (page  486),  and  some  Paleozoic  genera  still  having  their 
species.     The  facts  prove  unity  in  system  of  life  as  well  as  in  organic  and 
physical  law. 

IX.  A  head  ward  concentration  or  cephalization  of  the  structure  attend- 
ing generally  a  rise  in  grade,  and  the  reverse,  or  decephalization,  a  decline. 

X.  The  localization  of  tribes  in  time,  or  chronographically,  involved  in 
the  physical  progress  of  the  earth,  that  is,  in  its  progressing  climates,  and 
its  conditions  as  to  water  and  land.     As  now  there  are  different  zones,  and 
various  localizations  of  species  on  going  from  the  equator  to  the  poles,  so 
there  were  necessarily  successive  phases  and  increasing  diversity  in  the  life 
of  the  world  on  passing  from  the  warm  conditions  and  nearly  universal  seas 
of  early  time  to  the  present  age  of  frigid  polar  regions  and  greatly  differen- 
tiated seas  and  lands. 

Evidence  with  reference  to  evolution  by  variation.  —  The  propositions  above 
stated  read  like  the  heads  in  an  argument  for  the  evolution  of  the  kingdoms 
of  life.  They  were  so  recognized  many  years  before  Darwin's  first  publica- 
tion on  this  subject.  Most  of  them  were  used  by  Agassiz  in  his  lectures  on 
development,  —  by  which  he  meant  evolution ;  and  evolution  based  on  paleon- 


1030  HISTORICAL   GEOLOGY. 

tological  study,  having  therefore  the  successional  lines  which  such  study- 
ascertains  ;  but  different  in  method,  the  change  in  species  being  dependent, 
in  his  view,  on  creative  acts,  and  not  on  natural  variation.  All  students 
of  nature,  with  a  rare  exception,  then  believed  in  permanence ;  for  Lyell's 
chapter  against  the  transmutation  of  species,  in  the  successive  editions  of  his 
Principles  of  Geology,  had  seemingly  settled  the  question  against  Lamarck 
by  scientific  argument.  It  was  not  till  1859  that  Darwin's  work  was  pub- 
lished on  the  Origin  of  Species  by  means  of  Natural  Selection,  or  the  Preser- 
vation of  Favored  Races  in  the  Struggle  for  Life. 

The  principles  above  stated  are  all  in  accord  with  a  theory  of  evolution ;. 
and,  through  the  added  facts  of  later  years,  they  favor  the  view  of  evolution 
by  natural  variation.  Some  of  these  added  facts  are  the  following :  Botan- 
ists find  numerous  cases  among  existing  species  in  which,  owing  to  the  many 
varieties,  no  line  can  be  drawn  between  allied  species ;  and  other  cases  in 
which  modern  species  of  plants  are  but  slight  modifications  of  fossil  Tertiary 
species,  some  too  slight  to  be  called  distinct  species,  and  others  more  diver- 
gent up  to  those  of  good  distinctive  characters.  Similar  facts  occur  as  a 
consequence  of  migrations,  among  animals  as  well  as  plants.  Arctic  America 
contained,  in  Tertiary  time,  plants  so  much  like  species  existing  in  the 
forests  of  both  temperate  North  America  and  Japan  (page  939),  that  the 
former  have  been  pronounced  the  undoubted  progenitors  of  the  latter.  Along 
the  Pacific  coast  and  Gulf  coast  of  Central  America  there  are  so  many  iden- 
tical and  nearly  related  species  of  aquatic  animals  that  migration  during  a 
time  of  submergence  of  the  narrow  strip  of  land,  with  subsequent  variation, 
is  regarded  as  the  only  reasonable  explanation.  These  and  other  observa- 
tions have  proved  sufficient  to  make  all  zoologists  of  the  present  day,  like 
the  botanists,  believers  in  a  system  of  Evolution  by  variation. 

It  is  admitted  that  in  the  geological  record  cases  of  unbroken  gradation 
between  species  are  of  rare  occurrence.  But  the  geological  record  bears 
evidence,  in  all  parts,  of  imperfections.  It  is  imperfect,  (1)  because,  under 
the  most  favorable  circumstances,  only  a  small  part  of  the  existing  species 
could  have  been  fossilized ;  (2)  because  in  all  lands  there  are  great  breaks  in 
the  series  of  rocks,  as  is  known  from  comparing  the  rocks  of  different  conti- 
nents, and  even  different  regions  on  the  same  continent :  (3)  because  fossil- 
iferous  rocks  |re  almost  solely  of  aqueous  origin,  and  consequently  they 
contain  exceedingly  little  of  the  terrestrial  life  of  the  ancient  world  —  one 
species  of  Bir«  being  all  yet  discovered  in  the  world's  rocks  of  the  Jurassic 
period,  and  twl  species  of  Mammals  all  that  are  known  from  the  American 
Triassic  beds ;  (4)  because  marine  strata  that  were  formed  around  the  land 
when  it  was  at  a  higher  level  than  the  present  are  now  buried  in  the  ocean, 
and  are  therefore  inaccessible,  a  condition  that  has  affected  half  the  borders 
of  a  continent  for  several  successive  periods ;  (5)  because  only  a  small  part 
of  the  rocks  of  a  continent  are  open  to  view.  This  subject  has  been  abun- 
dantly illustrated  in  the  preceding  history  of  the  formations  and  their  life. 

But  transitions  have  been  nearly  filled  in  so  many  cases,  and  are  indi- 


GENERAL   OBSERVATIONS.  1031 

cated  so  plainly  by  the  very  gradual  steps  in  the  successional  lines ;  the 
progress  of  rudimentary  organs  may  so  often  be  traced  from  an  early  con- 
dition of  good  size  to  that  of  rudiments,  and  variations  in  existing  species 
are  so  often  wide  and  perplexing  to  the  systematist,  that  the  evidence  in 
favor  of  evolution  by  variation  is  now  regarded  as  essentially  complete. 

The  argument  from  the  facts  presented  on  page  929,  respecting  the 
descent  of  the  Horse,  is  strengthened  by  the  occurrence  among  modern 
horses  occasionally  of  a  small  pair  of  hoofs  growing  from  the  extremity  of 
the  splint  bones  of  each  foot  —  the  old  toes  lost  by  descent  back  again ;  and 
more  rarely  by  the  growth  of  a  full-sized  toe  from  one  of  these  bones,  on  all 
the  feet,  approximating  thus  to  horses  of  the  later  Tertiary  (Marsh,  Am. 
Jour.  Sc.,  xliii.  1892).  Birds,  now  standing  apart  from  other  Vertebrates  so 
stiffly,  as  animals  with  feathers,  short  tails,  and  bills  without  teeth,  in  former 
times  had  teeth  in  their  jaws,  and  long  tails,  like  Reptiles.  Moreover,  in 
the  Reptilian  age,  there  were  biped  Reptiles,  with  the  hollow  bones  and  some 
other  characteristics  of  Birds ;  and  also  Mammals  that  laid  eggs  like  Birds 
and  Reptiles,  —  as  they  continue  now  to  do  in  Australia. 

There  are,  however,  some  large  blanks  in  the  series  which  are  yet  unex- 
plained, although  investigators  have  been  at  work  over  the  subjects  for  scores 
of  years.  One  of  these  is  the  apparently  sudden  appearance  of  plants  of  the 
tribe  of  Angiosperms,  the  most  common  kind  of  Recent  time,  in  the  Lower 
Cretaceous ;  another,  the  still  more  remarkably  abrupt  introduction  of  ordi- 
nary or  placental  Mammals  as  successors  to  the  Marsupials  at  the  commence- 
ment of  the  Tertiary ;  another,  the  introduction  of  well-characterized  Fishes, 
without  the  discovery  of  their  precursors.  Such  facts  excite,  at  the  present 
time,  interest  in  further  study,  but  not  doubts  as  to  the  general  system  of 
progress.  Already  a  small  slender  fossil,  with  a  blade-like  sculling  tail  and 
terminal  mouth,  —  the  Palceospondylus  Gunni,  from  the  Devonian  of  Caith- 
ness, Scotland,  —  has  been  described  as  probably  a  primeval  Lamprey  (an 
eel-like  Cyclostome,  page  403).  But,  if  correctly  referred,  there  is  still  a 
very  wide  interval  between  it  and  the  early  Placoderms. 

Some  other  general  facts  respecting  successional  lines,  are  the  following : 

The  lines  of  succession  seldom  connect  the  grander  divisions  of^Jftsses  or  tribes. 
None  lead  directly  from  Macrural  to  Brachyural  Crustaceans,  or  from  An^mipod  to  Isopod 
kinds.  Instead,  the  group  of  Anomourans,  intermediate  between  the  two  tribes  first  men- 
tioned, was  the  course  of  successional  lines  in  geological  history,  and  of  branches  to  both 
the  Macrurans  and  Brachyurans.  In  a  similar  way  the  Anisopods,  intermediate  between 
the  Isopods  and  Amphipods,  or  the  typical  Tetradecapods,  were  the  source  of  branches  to 
these  tribes.  The  principle  is  in  accordance  with  that  respecting  comprehensive  or  syn- 
thetic types,  for  the  Anisopods  and  Anomourans  are  of  this  nature.  A  line  leads  direct 
from  the  higher  Ganoids  to  the  Amphibians ;  but,  instead  of  lines  from  Amphibians  to 
Reptiles,  and  thence  to  Birds  or  to  Mammals,  all  three  groups  —  Reptiles,  Birds,  and 
Mammals  —  were  probably  derived  directly  from  the  Amphibians.  Instead  of  succes- 
sional lines  between  Ungulates,  Carnivores,  and  Quadrumana,  these  three  groups  were 
probably  derived,  as  Cope  has  remarked,  from  some  common  tribe  in  the  earliest  Eocene. 
No  successional  lines  among  Insects  appear  to  have  passed  between  the  higher  tribes  of 


1032  HISTORICAL   GEOLOGY. 

Neuropters,  Orthopters,  Coleopters,  Lepidopters,   Hymenopters ;  but  each  was  derived 
from  some  early  comprehensive  forms. 

The  results  of  degeneration  afford  other  series  of  facts  of  the  highest  importance  with 
reference  to  the  origin  of  species.  Some  of  them,  and  a  few  of  the  principles  they  illus- 
trate, are  mentioned  on  pages  717,  931. 

Two  systems  of  evolution.  —  LAMARCK,  in  his  system  of  Evolution  (Phil. 
ZodL,  1809),  laid  down  as  one  chief  cause  of  variation,  the  use  and  disuse  of 
organs  or  parts,  —  use  causing  enlargement,  and  disuse  a  dwindling  even  to 
disappearance ;  and  one  of  his  illustrations  was  drawn  from  the  difference 
in  length  of  wing  of  the  tame  and  wild  Ducks.  He  put  forth,  as  other  sources 
of  change,  the  surrounding  physical  conditions  and  their  often  abrupt  changes, 
and  referred  also,  in  an  imperfect  way,  to  the  effect  of  biological  associations, 
or  the  influence  of  the  living  species  of  a  region  on  one  another.  The  im- 
portance of  the  principle  of  heredity  was  also  recognized.  He  added  to  his 
system  the  principle  —  a  tendency  upward. 

DARWIN,  in  his  work  of  1859,  recognized  the  obvious  causes  of  variation, 
but  claimed  that  these,  and  all  means  of  change,  derived  their  efficiency  from 
action  under  the  principle  of  "Natural  Selection,"  as  indicated  in  the  title 
of  his  work.  He  elucidated  the  subject  of  evolution  by  many  illustrations 
of  the  effects  of  breeding  and  culture  under  man's  care  and  guidance ;  by 
his  study  of  variation  among  living  plants  and  animals,  wild  and  domesti- 
cated, publishing  a  separate  work  of  great  value  on  Animals  and  Plants 
under  Domestication ;  by  full  illustrations  of  the  laws  of  heredity;  and  by 
new  facts,  almost  a  revelation  to  science,  relating  to  the  living  environments 
of  species,  and  the  consequent  interdependence  and  interaction  of  associated 
kinds  in  both  kingdoms  of  life. 

According  to  the  principle  of  natural  selection,  "  an  animal  or  plant  that 
varies  in  a  manner  profitable  to  itself  will  have,  thereby,  a  better  chance  of 
surviving,"  and  of  contributing  its  qualities  and  progressive  tendency  to  the 
race,  while  others  not  so  favored,  or  varying  disadvantageously,  disappear. 
The  favored  ones,  or  the  "  naturally  selected,"  are  one  or  two,  or  a  few,  of  a 
herd,  or  of  a  region;  and  the  unfavored  ones,  fated  to  disappear  because 
unadaptable,  include,  theoretically,  all  the  rest.  The  principle  of  selective 
breeding  is  used  in  the  development  of  the  favored  ones ;  for  these  have  to 
be  separated  from  the  rest  of  the  herd  for  success,  as  in  man's  selection. 
The  adaptations  are  to  any  kind  of  condition,  whether  favorable  to  the 
highest  or  to  the  lowest  developments,  so  that  progress  under  the  principle 
may  be  upward  or  downward.  The  origin  of  variation  is  not  considered. 
Everything  in  nature  varies,  and  changing  conditions  are  always  adding  to 
the  variations.  However  produced,  the  individual  that  is  profited  by  a 
variation  survives,  propagates  its  characteristics,  and  becomes  the  type  of  a 
species,  while  "multitudes"  are  left  behind  in  the  struggle  with  adverse 
environments;  and  thus  the  new  species,  in  the  end,  stands  widely  apart 
from  other  species. 

In  the  expression,  "preservation  of  favored  races. in  the  struggle   for 


GENERAL   OBSERVATIONS.  1033 

life,"  the  direct  effects  of  struggle  or  labor  on  the  individual,  that  is,  the 
beneficial  and  other  effects  of  struggle  itself,  are  not  intended,  though  not 
•excluded;  only  the  effects  of  struggle  or  strife  on  disappearings  and  sur- 
vivals, under  the  changing  conditions,  are  referred  to. 

Augmentation  of  variations  by  interbreeding  fundamental  in  evolution.  — 
Man,  by  selective  breeding  carried  on  for  successive  generations,  has  obtained 
-cattle  with  long  horns,  short  horns,  and  no  horns ;  fowls  with  large  combs 
on  the  head,  with  no  combs,  or  with  a  rosette  of  feathers  in  place  of  the 
•crested  comb,  with  bare  legs  and  with  feathered  legs,  with  long  spurs  and  long 
legs  for  fighting,  and  with  no  spurs  and  short  legs,  and  with  great  diversity 
•of  color;  Pigeons  with  long  bills  and  with  short  bills,  giving  them  characters 
belonging  to  different  tribes  of  Birds,  with  long  or  short  legs,  with  the  fan- 
like  tail  of  a  Peacock  and  an  attendant  increase  in  the  number  of  feathers. 
And,  similarly,  diversity  has  been  obtained  in  the  case  of  many  other  species. 
The  varieties  obtained  range  through  a  vastly  wider  diversity  of  characters 
than  occurs  under  any  species  in  nature. 

It  is  perceived  that  the  law  of  nature  here  exemplified  is  not  "like 
produces  like,"  but  like  with  an  increment  or  some  addition  to  the  variation. 
•Consequently,  the  law  of  nature,  as  regards  the  kingdoms  of  life,  is  not 
permanence,  but  change,  evolution. 

Great  plasticity  in  organic  structures  under  variant  agencies.  —  This  is 
another  principle  taught  by  the  above-mentioned  facts.  This  plasticity 
under  any  type  is  usually  most  prominent  in  one  or  two  of  the  kinds  of 
organs,  and  consequently  it  leads  to  the  evolution  of  species  in  lines,  deter- 
mining genera  or  natural  groups. 

"  A  tendency  upward."  determined,  in  the  Animal  Kingdom,  by  the  existence 
of  a  cephalic  nervous  mass  or  brain.  —  This  principle  is  explained  on  page 
439. 

Articulates  and  Vertebrates  first  appear  as  multiplicate  species :  as  exem- 
plified in  Worms,  the  earliest  Crustaceans,  and  Fishes,  and  in  the  Myriapods, 
successors  to  the  Worms.  Through  subsequent  changes,  types  having  a 
definite  or  normal  number  of  parts  are  introduced,  as  Insects  after  Myria- 
pods (page  721),  Amphibians  after  Fishes  (page  725),  and  so  on. 

In  degeneration,  Reptiles  and  Mammals,  in  some  cases,  have  become  mul- 
tiplicate: as  exhibited  in  the  vertebrae  and  teeth,  and  sometimes  in  the 
phalanges  and  number  of  the  digits.  (Pages  797,  931.) 

Natural  selection  not  essential  to  evolution,  variations  being  effectual  with- 
out it.  —  The  theory  of  natural  selection  is  based  on  the  assumption  that 
variations  come  singly  or  nearly  so,  and  that  the  selected  are  therefore  few 
•compared  with  the  multitudes  that  disappear.  The  idea  is  derived  from 
facts  afforded  by  domesticated  or  cultivated  races.  But  such  races  are  in  a 
large  degree  artificial  products,  selective  methods  carrying  the  individuals 
rapidly  in  the  direction  of  the  variation,  and  producing,  in  a  few  scores  of 
generations^  divergencies  that  in  wild  nature  would  require  thousands  of 
years.  The  structures  are  therefore  in  a  strained  or  artificial  state,  and 


1034  HISTORICAL    GEOLOGY. 

deteriorate  when  care  ceases.  But  in  wild  nature  variations  are,  in  general,, 
the  slow  and  sure  result  of  the  conditions  —  the  organic  conditions  on 
one  side  and  the  physical  and  biological  on  the  other;  they  should  occur,, 
generally,  in  a  large  part  of  the  associated  individuals  of  a  species ;  and 
being  Nature-made,  the  results  are  permanent.  When,  therefore,  a  variation 
appears  that  admits  of  augmentation  by  continued  interbreeding,  progress, 
should  be  general;  and  the  unadaptable  few  should  disappear,  not  the; 
«  multitudes.7' 

Under  such  a  system  of  evolution,  —  evolution  by  regional  progress, — 
the  causes  of  variation  mentioned  by  Darwin  are  all  real  causes.  But  they 
act  directly,  after  the  Lamarckian  method,  without  dependence  for  success  on 
the  principle  of  natural  selection.  Use  and  disuse,  labor,  strife,  physical! 
changes  or  conditions,  and  organic  influences  act  as  such,  and  have  their 
direct  effects.  The  plants  that  migrated  in  the  Tertiary  from  the  Arctic 
regions  southward  over  Japan  and  North  America,  and  became  new  species 
on  the  way,  simply  changed.  That  is  the  sum  of  knowledge  on  the  subject. 

Man  affords  an  example.  The  gradual  gain  of  some  races  in  lands  and 
supremacy,  and  the  disappearance  of  the  inferior  races,  is  an  example  of  the- 
Survival  of  the  Fittest,  or  Natural  Selection.  But  the  superior  races  de- 
rived the  power  which  led  to  their  survival  and  preeminent  position  through 
favoring  conditions  in  environments,  that  is,  in  geographical,  geological,  and! 
biological  conditions  and  resources ;  through  the  powers  of  endurance,  the 
courage,  the  mind  power,  the  will  power,  which  conflict  with  nature  and  with 
other  races  of  men  in  the  world  is  fitted  to  develop ;  and  through  the  power 
and  self-assurance  which  comes  of  a  high  moral  sense.  Hence  victory,  sur- 
vival. The  survival  of  the  fittest  is  a  fact ;  and  the  fact  accounts  in  part 
for  the  geographical  distribution  of  the  races  of  men  now  existing  and  still 
in  progress ;  but  not  for  the  existence  of  the  fittest,  or  for  the  power  that 
has  determined  survival. 

Natural  selection,  a  means  of  determining  the  successive  floras  and  faunas- 
of  the  world;  a  prominent  cause  of  the  geographical  distribution  of  species.— 
Natural  selection  is  literally  selection,  survivals ;  the  survivors  are  those 
that  continue  on  to  make  faunas  and  floras. 

Independent  derivation  of  allied  species.  —  The  existence  of  related 
species  under  a  genus  or  family  on  two  or  more  continents,  or  in  widely 
distant  regions,  has  brought  up  the  question  whether  such  occurrences  are 
not  due  in  some  cases  to  independent  derivation.  Migration  accounts 
unquestionably  for  a  large  part  of  them ;  but  it  is  doubtful  whether  it 
accounts  for  all.  If  not  for  all,  if  the  evolution  has  gone  forward  parallel- 
wise  on  different  continents,  then  organic  law  is  not  only  the  source  of 
change,  the  environments  subordinate  in  influence,  but  the  source  of  a 
system  of  changes  in  the  progressing  evolution.  The  subordination  to  the 
law  of  cephalization  —  that  anterior  concentration  in  the  animal  structure,, 
involving  posterior  abbreviation,  attends  progress  in  grade  —  accords  with 
this  idea  of  organic  control. 


GENERAL   OBSERVATIONS.  103& 

This  view  of  the  subordination  of  organic  evolution  to  general  laws  is 
sustained  by  the  paleontologist  Professor  A.  Gaudry,  of  Paris,  in  his  review 
of  the  parallelism  between  Europe  and  America  in  the  succession  of  types 
from  the  Cambrian  upward  (Bull.  Soc.  Geol.  de  France,  December,  1891). 
He  compares  the  correlate  tribes  through  the  successive  stages  of  progress, 
and  the  gradual  changes  by  which  old  characteristics  disappeared  and  new 
features  were  developed  for  the  two  distant  regions,  notwithstanding  the 
differences  that  existed  in  climatal  and  other  conditions ;  and  he  concludes 
that  these  and  similar  facts  are  not  all  explainable  by  migrations,  but  only 
by  evolution  under  general  laws  of  progress. 

Origin  of  species. — The  origin  of  the  special  causes  for  each  line  of 
change  or  variation,  which  Darwin  did  not  undertake  to  study  out,  is  yet 
very  imperfectly  understood.  The  paragraphs  on  the  evolution  of  the  Horse 
and  the  Artiodactyl,  on  page  929,  and  others  bearing  in  the  same  direction, 
show  some  success.  It  is  admitted  that  (1)  bones  will  coossify  if  movement 
between  them  ceases ;  (2)  that  the  progressive  enlargement  of  one  organ  or 
part  may  cause  the  dwindling  of  others  adjoining ;  (3)  that  running  under 
an  impulse  would  lead  to  a  rising  of  the  foot  on  the  toes,  to  secure  greater 
length  of  lever  and  greater  speed;  (4)  that  activity  in  the  limbs  may  deter- 
mine adjustments  in  the  position  of  the  ankle  bones  fitted  for  greatest 
strength  and  security ;  (5)  that  the  use  of  the  teeth  may  lead  to  increased 
complexity  of  structure. 

But  from  the  statements  with  regard  to  the  Horse  and  Artiodactyl,  it 
may  be  thought  possible,  also,  that  the  great  elongation  of  the  foot,  chiefly 
of  the  metacarpals  and  metatarsals,  would  be  a  natural  consequence  of  the 
rhythmic  stroke  of  the  foot  in  running,  this  inducing  a  variation  that  was 
continued  in  growth  by  interbreeding.  And  this  apparent  success  in  ex- 
plaining leads  to  the  suggestion  that  the  graceful  form,  so  general  in  fleet 
animals,  may  be  a  result  of  the  free  movements  of  all  parts  of  the  structure 
in  running ;  and  that  the  horns  in  the  Kuminants  and  other  Ungulates  may 
have  come  from  a  variation  commenced  by  the  strokes  made  by  the  forehead 
or  front  of  the  head,  in  conflicts. 

But  another  Artiodactyl,  the  "  high-reaching  "  Giraffe,  puts  a  check  to 
speculation:  for  it  has  the  anterior  pair  of  legs  much  the  longer,  the  foot 
portion  alone  three  feet  long;  and  the  neck  more  than  triple  the  ordinary 
length  in  Ruminants,  owing  to  the  great  elongation  of  six  of  the  seven 
vertebrae.  The  elongation  of  the  legs  has  the  same  purpose  as  that  of  the 
neck — "high-reaching  in  quest  of  food."  The  question  comes  up  —  How 
should  the  Giraffe  have  had  to  run  to  make  its  fore  legs  grow  faster  than 
the  hind  legs,  and  what  kind  of  antics  would  have  started  the  change  in 
the  neck  ?  It  has  to  be  supposed  that  the  requisite  augmentative  varia- 
tions were  somehow  begun,  and  that  under  interbreeding,  accelerated  growth 
went  forward.  But  the  origin  of  the  variation  is  without  explanation. 
And  so  it  is  for  the  most  part  throughout  the  Kingdoms  of  life.  Enough 
is  known  to  encourage  study. 


1036  HISTORICAL   GEOLOGY. 

It  is  of  no  avail  to  speak  of  chance  variations.  The  use  of  the  word 
chance  indicates  personal  ignorance.  Chance  has  no  place  in  nature's  laws, 
and  can  have  none  in  nature-science. 

Man's  origin  has  thus  far  no  sufficient  explanation  from  science.  His 
close  relations  in  structure  to  the  Man- Apes  are  unquestionable.  They  have 
the  same  number  of  bones  with  two  exceptions,  and  the  bones  are  the 
same  in  kind  and  structure.  The  muscles  are  mostly  the  same.  Both  carry 
their  young  in  their  arms.  The  affiliations  strongly  suggest  community  of 
descent.  But  the  divergencies  mentioned  on  page  1018,  especially  the  cases 
of  degeneracy  in  Man's  structure,  exhibited  in  his  palmigrade  feet  and  the 
primitive  character  of  his  teeth,  allying  him  in  these  respects  to  the  Lower 
Eocene  forms,  are  admitted  proof  that  he  has  not  descended  from  any 
•existing  type  of  Ape.  In  addition,  Man's  erect  posture  makes  the  gap  a 
very  broad  one.  The  brute,  the  Ape  included,  has  powerful  muscles  in  the 
back  of  the  neck  to  carry  the  head  in  its  horizontal  position,  while  Man  has 
no  such  muscles,  as  any  one  of  the  species  can  prove  by  crawling  for  a 
while  on  "  all  fours."  Beyond  this,  the  great  size  of  the  brain,  his  eminent 
intellectual  and  moral  qualities,  his  voice  and  speech,  give  him  sole  title  to 
the  position  at  the  head  of  the  Kingdoms  of  Life.  In  this  high  position, 
he  is  able  to  use  Nature  as  his  work-mate,  his  companion,  and  his  educator, 
and  to  find  perpetual  delight  in  her  harmonies  and  her  revelations. 

The  search  for  "  missing  links "  has  been  carried  forward  with  deep 
interest  during  recent  years.  But  although  fossil  skeletons  have  been  found 
among  the  remains  of  Pleistocene  Mammals  in  Europe  and  America  none 
show  any  indication  of  departure  from  the  erect  posture,  or  have  smaller 
brain  cavity  than  occurs  among  existing  races  of  Men.  The  most  probable 
regions  for  the  discovery  of  precursor  forms  are  those  of  Africa  and  the 
East  Indies.  Already,  since  these  closing  pages  were  first  in  type,  the 
report  has  come  of  the  discovery,  in  the  Pleistocene  deposits  of  Java,  of  an 
imperfect  cranium,  a  femur  bearing  evidence  of  prolonged  disease,  and  a  molar 
tooth,  which  the  describer,  E.  Dubois,  has  named  Pithecanthropus  erectus, 
placing  it  between  the  Man-Apes  and  Man.  Others  make  the  remains  those 
of  a  low-grade  Man,  or  of  an  idiot.  Since  Man's  structural  relations  are,  in 
several  respects,  closest  with  the  precursors  of  the  Quadrumana  (p.  1017),  his 
derivation  from  any  known  type  of  Man- Ape  has  been  pronounced  impossible. 

Whatever  the  results  of  further  search,  we  may  feel  assured,  in  accord 
with  Wallace,  who  shares  with  Darwin  in  the  authorship  of  the  theory  of 
Natural  Selection,  that  the  intervention  of  a  Power  above  Nature  was  at  the 
basis  of  Man's  development.  Believing  that  Nature  exists  through  the  will 
and  ever-acting  power  of  the  Divine  Being,  and  that  all  its  great  truths,  its 
beauties,  its  harmonies,  are  manifestations  of  His  wisdom  and  power,  or,  in 
the  words  nearly  of  Wallace,  that  the  whole  Universe  is  not  merely  depen- 
dent on,  but  actually  is,  the  Will  of  one  Supreme  Intelligence,  Nature,  with 
Man  as  its  culminant  species,  is  no  longer  a  mystery. 


INDEX. 


INDEX. 


A  star  (*)  after  the  number  of  a  page  indicates  that  there  is  a  reference  on  the  page  to  a  figure  of  the 
•species  or  object  mentioned  ;  and  a  section  mark  (§)  implies  that  the  page  contains  a  definition,  explanation, 
or  characteristic  of  the  word  or  object  mentioned. 


Aa  (lava-stream),  287§*,  288,  289 

Aalenian,  790 

Aar  Glacier,  237,  248,  251 ;  investi- 
gations by  Hugi  and  Agassiz,  243 

Abies,  859 

Abietites  dubius,  839  ;  Linkii,  834 

Abrasion,  131,  159,  168,  202,  804, 
805,  806,  941 ;  assorts  in  propor- 
tion to  hardness,  169 ;  see  also 
Glacial  abrasion,  Scratches 

Abrolhos  Islands,  867 

Abyssal  depths  of  the  ocean,  229 

Abyssinia,  26  (plateau),  33,  34,  177 

Acacia,  921 

Acadian  area  of  Carboniferous  and 
Subcarboniferous,  635 

—  period.    See  Cambrian,  Middle 

—  protaxis,  444 

—  Range,  389,  391,  732 

—  Triassic  area,  740,  741 

—  trough,  461,  467,  536,   537,   541, 
543,  558,  633,  708,  715,  732,  743 

—  upturning,  736 
Acalephs,  430§ 
Acanthaspis  armata,  588* 
Acantherpestes,  701 ;  major,  691 
Acanthoceras  Lyelli,  865;  mammil- 

lare,    855,    865;    Mantelli,    866; 

Rhotomagense,  866 
Acanthodes,  620 ;  affinis,  620*  ;  pris- 

cus,  620 

Acanthodians,  416 
Acanthopholis  horridus,  863 
Acanthotelson   Eveni,  691 ;  Stimp- 

soni,  678*,  691 
Acephals,  424§ 
Aceratherium,  926 
Acervularia,  625 ;  pentagona,  592 
Achaenodon,  918 
Achyrodon,  789* 
Acid.     See  Boracic  acid  ;  Carbonic ; 

Humus ;  Organic ;  Sulphuric 
Acidaspis,   513,  515,  520,  521,  561, 

567,  568,  579,  586,  591,  599  ;  Bar- 

randii,  565*  ;  Brightii,  565*,  567  ; 

callicera,  587*,  591 ;  coronata,  567 ; 

hamata,  567 ;  Jamesii,  520 ;  Rom- 

ingeri,  587*,  599 ;  tuberculata,  561, 

562*,  578,  579 
Acipenser,  923 


Acleistoceras,  591,  602 

Aclis  robusta,  690 

Aconcagua,  296 

Acrocrinus,  690 

Acrodus,  772  (first),  783 ;  minimus, 

416*,  774 ;  nobilis,  416* 
Acrogens,  435§ 

Acrolepis,  705 ;  Sedgwickii,  707 
Acrothe'e,  481 ;  Matthewi,  475* 
Acrotreta,  520 ;  gemma,  471*,  516, 

573 ;  subconica,  573 
Actinia,  429*,  431§,  516 
Actinoceras,    501,    546,    549,    567; 

Bigsbyi,  506,  508*,  514;    crebri- 

septum,  516,  524 ;  verum,  866 
Actinoconchus  planosulcatus,  646 
Actinocrinus,    520,   567,    597,    646, 

690  ;    proboscidialis,    640*,    646 ; 

simplex,  567  ;  tenuistriatus,  625 
Actinocyclus  Ehrenbergii,  894* 
Actinoids,  431§,  525 
Actinolite,  67*§ 
Actinolyte,  89§ 
Actinopteria,  621 
Actinoptychus  senarius,  437*,  894* ; 

undulatus,  894* 
Adams,  Mt.,  296 
Adapisorex,  925 
Adelsberg  cave,  207 
Adipocere,  143,  154 
Adirondack   Mts.  and   region,   85, 

204,  384,  442;  Arctic  plants  on 

summits  of,  945 
Adjutants,  923 
Admete  viridula,  984 
Admiralty  Islands,  38,  39 
Adobe,  195§ 
Adocus   agilis,   850;   beatus,   850; 

punctatus,  850 
Adriatic  Sea,  41,  212 
.^Echmina,  562 
^Eglea,  708 
^Eglina,  521 ;    grandis,  520 ;  mira- 

bilis,  520 
^Egoceras  capricornus,  781* ;  Jame- 

soni,  790 ;  planorbis,  790 
^Egyrite,  85 
^Elurodon,  919 
^Eon,  406§,  407 
^Epyornis,  54,  1014,  1019 

1039 


Afghanistan,  920 

Africa,  17,  21,  22,  23,  26  (plateaus), 
30,  31,  33*.  51,  165,  297,  394,  395, 
406,  435,  674,  737 ;  volcanoes  in 
the  Bight  of  Benin,  296;  coral 
reefs  of  eastern  coast,  145 

— ,  Carbonic  rocks  in,  632, 693 ;  Up- 
per Silurian,  563;  Triassic,  632, 
741 ;  Jurassic,  873  ;  Cretaceous, 
857,  859,  873.  See  further  South 
Africa 

Agalmatolite,  68§ 

Agalmatolyte,  84§ 

Agaricus,  688 

Agassizocrinus,  690 

Agassizodus,  692;    variabilis,  680* 

Agathaumas,  828,  847;  sylvestris, 
847,  856 

Age  of  the  Earth,  1023 

Agelacrinites,  516 

Agelacrinus  BiUingsi,  514 

Agnostus,  473,  475,  481,  482,  486, 
500,  516,  520,  521;  Acadicus, 
476*;  interstrictus,  476*;  Kje- 
rulfi,  482;  nobilis,  473*;  Rex, 
481*,  482 

Agnotozoic,  445,  447 

Agoniatites,  599 

Agriochoerus,  918 

Agriomeryx,  918 

Agui  Range,  365 

Alabaster,  69§ 

Alachua  clays,  891 

Alaska,  23,  234  (snow-line),  297,  582, 
948  (fiords) 

— ,  Triassic  in,  747;  Cretaceous, 
818,  820,  834,  868,  872  (climate) ; 
Tertiary,  892,  893,  939  ;  Glacial, 
945,  948 

"Albatross,"  60,230 

Albemarle  Sound,  224* 

Albert  Mine,  N.B.,  639 

Albertia,  770 

Albertite,  662 

Albian  group,  815,  858,  859,  865 

Albirupean  group,  819 

Albite,  64§,  82,  83 

Alca  impennis,  1014 

Alces  Americanus,  1002 

Alcyonaria,  431§ 


1040 


INDEX. 


Alcyonium,  431§ 

Alcyonoids,  481§,  525 

Alder,  837,  922 

Alethopteris,  639,  645,  671,  685,  698, 
699,  704,  756;  discrepans,  622; 
gigas,  705;  Helen*,  645;  lonchi- 
tica,  670*,  689  ;  Serlii,  689  ;  Whit- 
byensis,  791 

Aleutian  Islands,  40,  296 

Algae,  56,  60,  72,  79,  140,  153,  156, 
241 ;  the  earliest  plants,  409*,  441, 
454  ;  in  hot  waters,  152,  308,  437, 
441,454 

Algeria,  920 

Algerite,  320 

Algonkian  formation,  445,  447,  469 

AUeghany  Mts.,  41,  106,  188,  636, 
638,  745;  plants  on  summits, 
driven  south  by  the  ice,  946 

Alligator,  54,  55,  681 

Allodon,  768 ;  fortis,  767*  ;  laticeps, 
767* 

Allomys,  918 

Allophane,  638 

Allorchestes,  347 

Allorisma  subcuneata,  675*,  690 

Allosaurus,  766 ;  medius,  836 

Alluvial  cones,  99,  194§,  195*,  196 

Alluvium,  81§,  98, 191, 198,  200,  228, 
366 

Almond,  921 

Alps,  23,  32,  110,  233,  234  (snow- 
line),  265,  266,  310,  367*,  368*  391, 
463,  738,  812,  943  ;  coal-formation, 
734 ;  glaciers  of,  235*,  236*,  237*, 
239,  243,  244,  248,  251 ;  great  fault 
in,  734 ;  section,  east  of  Lucerne, 
102* 

— ,  Archaean  in,  368 ;  Upper  Silu- 
rian, 573 ;  Triassic,  757,  768,  769, 
773,  774;  Jurassic,  774,  780,  791, 
793;  Cretaceous,  859,  864;  Ter- 
tiary, 347,  367,  380,  919,  920, 
921,  982  (upturning),  936  (eleva- 
tion) 

Altai  Mts.,  32,  33,  200,  568,  569 

Altamaha  grits,  891 

Alum  Bluff  sands,  890,  891 

Alum  shale,  80§ 

Alumina,  61§ 

Aluminum  sulphates,  alums,  119, 
126,  138,  294,  335 

Amaltheus  ibex,  790  ;  spinatus,  790 

Amargura  Island,  296 

Amazon  River,  24,  30 ;  drainage 
area  of,  172;  eager,  212,  215; 
floods  of,  177,  183  ;  slope  of,  173 

Amazonian  group,  867 

Amber,  143,  838,  922 

Amblotherium,  789* 

Amblygonite,  449 

Amblypterus,  692,  702,  772 

Amblyrhizainundata,  1001 

Ambocoelia  gregaria,  621 ;  umbo- 
nata,  598*,  601,  620,  621 

Ambonicardia  Cookii,  837 

Ambonychia  attenuata,  514;  belli- 
striata,  507*  ;  radiata,  511*,  516 

Amboy  clays,  837 

Ambrym  Island,  296 

American  continent,  North,  growth 
of,  714-716 


418,  901 ;  Amia  family,  783, 


Amianthus,  319§ 

Ammodon  beds,  894 

Ammonia,  124,  137 

Ammonites,  or  Ammonoids,  402, 
424,  869  ;  Devonian,  869  (first) ; 
Permian,  686 ;  Triassic,  756,  757*, 
771;  Jurassic,  749,  758*,  759*, 
760,  781*  (number  of  British), 
791, 792, 793, 861,  869 ;  Cretaceous, 
812,  818,  836,  841,  842*,  855,  861, 
862*,  865,  867,  869,  877 

Ammonites,  757,  774,  916  ;  acanthi- 
cus,  791 ;  aspidioides,  790 ;  Astier- 
ianus,  865  ;  athleta,  791 ;  auritus, 
865;  bifrons,  790;  bimammatus, 
790 ;  biplex,  760,  791 ;  Bucklandi, 
790;  Burgundise,  790;  canalicula- 
tus,  790 ;  cornplexus,  855 ;  conca- 
vus,  760 ;  cordatus,  790  ;  cristatus, 
865;  decipiens,  790;  Delawaren- 
sis,  854;  Deshayesi,  864;  discus, 
790;  ferrugineus,  790;  Gallici, 
866;  Gaytani,  792;  Gervillianus, 
865 ;  gigas,  791 ;  Gowerianus,  790  ; 
Guadalupae,  855;  Herveyi,  790; 
Humphriesianus,  790  ;  ibex,  790 ; 
inflatus,  865;  interruptus,  865; 
Jamesoni,  790 ;  jugalis,  916 ;  Ju- 
rensis,  790 ;  Lamberti,  790;  lautus, 
865 ;  Leonensis,  837 ;  Lewesiensis, 
862;  M'Clintocki,  760,  792;  macro- 
cephalus,  790,  791 ;  rnammillaris, 
865;  Mariae,  790;  Mississippien- 
sis,  854;  Mullananus,  855;  Mur- 
chisonae,  790;  mutabilis,  790; 
Noricus,  865;  Parkinsoni,  790, 
791 ;  pedernalis,  836  ;  peramplus, 
866;  placenta,  842*;  planorbis, 
790;  pleurasepta,  855;  plicatilis, 
790 ;  ptychoicus,  791 ;  radians, 
790  ;  radiatus,  865  ;  Rhotomagen- 
sis,  866;  serpentinus,  790;  spi- 
natus, 790  ;  suprajurensis,  791  ; 
Swallovi,  854 ;  tenuilobatus,  790 ; 
Texanus,  855,  866;  tricarinatus, 
866 ;  varicosus,  865 ;  vespertinus, 
867;  Wosnessenski,  760 

Ammonium  chloride,  294 ;  nitrates, 
118 

Ammosaurus,  753 

Amnigenia,  612§ 

Amoeba,  433 ;  AmoeboSds,  419 

Ampelite,  81§ 

Amphibamus  grandiceps,  682,  683*, 

Amphibians,  54,  409*  (time  range), 

414,  415,  416,  417,  681,  706,  795, 796 
— ,  Reign  of,  460 
— ,  Relation  to  Mammals,  794 
— ,  Paleozoic,  725-726,  727 
— ,  Subcarboniferous,  643,  644,  645*, 

700 
— ,  Carboniferous,  657,  661,  674,  681, 

682, 683*,  684,  692,  693, 703, 704, 726 
— ,  Permian,  686*,  687*,  706,  869 
— ,  Triassic,    742,  751*,  758,    772*, 

796,  869 

— ,  Jurassic,  760,  796 
— ,  Cretaceous,  826,  869,  870 
Amphibole,  67§ 


Amphibolyte,  89§ 

Amphigene,  85 

Amphigenia  elongata,  579,  590 

Amphilestes,  789*  ;  Broderipi,  789* 

Amphion,  500,  502,  516,  521 ;  Cana- 

densis,  502* 
Amphioxus,  418§,  725 
Amphipods,  420*,  421  §,   438,  439§,. 

565,  707 

Amphitragulus,  926 
Amphitylus,  789* 
Amplexus,  552 ;  Hamiltoniae,  601 
Ampullina,  Fischeri,  917;  solidula, 

916 
Ampyx,  481,  500,  520,  521  ;   nudus, 

519*,  520  ;  Salteri,  520 
Amsopus  Deweyanus,  751* ;  graci- 

lis,  751* 
Amusium,  760,  917;  Mortoni,  917; 

simplicum,  854,  855 
Amygdalocystites,  514 
Amygdaloidal  cavities,  68,  98,  836,. 

337,  342 

—  rocks,  78§ 
Amygdules,  339 
Amynodon,  907,  918 
Amyzon  beds,  886,  893 
Anabacia  hemisphserica,  790 
Anacodon,  918 

Analcite,  68,  339 

Analyses  of  bones,  73  ;  of  coal  (see- 
Coal);  coprolites,  73;  corals,  72; 
granite,  82,  83;  limestones;  78, 
79  ;  plants,  74,  75 ;  shells,  72 ;  vol- 
canic rocks,  82-89 

Ananchytes,  59  ;  ovalis,  854 ;  ovatus,. 
860*,  866 

Anaptomorphus,  918 ;  homunculus, 
906* 

Anarthrocanna  Perryana,  622 

Anastrophia,  562,  579 ;  interplicata, 
548*,  551,  569  ;  Verneuili,  561* 

Anatifa,  420*,  421  § 

Anatimya  papyracea,  855 

Anchippodus,  904,  918;  minor,  904*,, 
905 

Anchisauridae,  792 

Anchisaurus,  753;  colurus,  753* 

Anchitherium,  911,  919,  927 

Anchor-ice,  232§ 

Anchura  abrupta,  854 ;  Americana,. 
841*,  855 

Ancilla  ancillops,  916 

Ancodus,  918 

Ancyloceras,  760  ;  gigas,  865  ;  Math- 
eronianum,  862* ;  Remondi,  760, 
837 

Andalusite,  65*§,  66,  83,  310,  315, 
318,  319,  449 

Andalusitic  rocks,  82,  83,  84 

Andes,  earthquake  in,  349  ;  glaciers 
in,  977  ;  height  of,  26,  296 ;  slopes 
of,  27,  31 ;  snow  line  of,  234;  vol- 
canoes, 296,  297 

— ,  Archaean  in,  456 ;  Carboniferous, 
711;  Jurassic,  760;  Cretaceous, 
857  ;  Tertiary,  365,  392,  935 ;  Qua- 
ternary, 392 

Andesite,  64§,  273 

Andesyte,  86§,  87,  272,  273,  276,, 
301*,  304,  339,  341,  518,  811 

—  rocks,  273,  274,  296 


INDEX. 


104T 


Andromeda,  887  ;  affinis,  839 ;  Par- 
latorii,  838* 

Andromedites,  922 

Aneimites  obtusus,  609*,  611 

Angau  Island,  150 

Angiosperms,  409,  434,  435§ ;  Cre- 
taceous, 816,  831,  832*,  833,  837, 
838*,  839,  859,  868;  Tertiary, 
895,  921 

Anglesea,  309,  440 

Anglesite,  335 

Angoumian,  859,  866 

Anguillaria  Cumminsi,  854 

Anhydrite,  69§,  120,  121,  125,  128, 
138 

Animal  kingdom,  9,  413,  414 

Animals,  geographical  distribution, 
52,  53;  materials  they  afford  to 
rock-making,  140-141,  144-152 

—  and  plants,  distinctive  character- 
istics, 413-414 

Animikie  group,  446,  469 
Anisomyon,    855;      borealis,    855; 

Haydeni,  855 

Anjou,  Faluns  beds  of,  926 
Annabon  Island,  297  (volcanoes) 
Annelids,  55,   157,  423,  427,  438§, 

720,  721,  723 
Annularia,   519,   671,  685,  699,  704, 

718 ;    carinata,   704,  705*  ;    longi- 

folia,  689,  692,  704 ;  minuta,  704 ; 

radiata,    704 ;     Eomingeri,    560  ; 

sphenophylloides,  689,  692,  704 
Anodonta,  837 

Anotnalocaris  Canadensis,  476, 477* 
Anomalocrinus,  516 
Anomalocystites,    562  ;    oornutus, 

559* 

Anomalopteryx,  1014 
Anomia,     828  ;      argentina,     854  ; 

ephippoides,  915 ;  micronema,  855 
Anomocare,  482 
Anomodontia,  688 
Anomodonts,  688,  707,  772,  773 
Anomcepus  scambus,  752* 
Anomozamites  elegans,  756* 
Anona  robusta,  839 
Anoplia  nucleata,  579 
Anoplophora  lettica,  774 ;  Munsteri, 

774 

Anoplotheres,  924§ 
Anoplotherium,    926,    927;     com- 
mune, 926  ;  secundarium,  926 
Anorthite,     64§,     65,     82,    86,    87, 

88,  273,  313,   318,   319,   323,   324, 

802 

Anorthite  rock,  87§ 
Anorthityte,  87f 
Ant.    See  Ants 
Ant-eater,  54,  925,  1002 
Antarctic    continent,   737,  798;    in 

the    Quaternary,  1019;    see   also 

Gondwana  Land 

—  ice-barrier,  252 

—  islands,  17 

—  pole,  17 

—  regions,  737  ;  glaciers,  233,  241 ; 
volcanoes,  295,  296,  297 

Antedon,  429 
Antelope  Park,  178 
Antelopes,    924,  927 
Antholithes,  674  ;  Pitcairnae,  673* 

DANA'S  MANUAL  —  66 


Anthozoans,  431§ 

Anthracerpes  typus,  691 

Anthracerpeton  crassosteum,  703 

Anthracite,  74,  315,  453,  648,  654, 
655*,  657,  661,  695,  714,  732,  826 ; 
composition,  662,  663,  712,  713; 
in  geodes,  493,  497 ;  of  the  Cal- 
ciferous,  493 

-,  origin  of,  713-714 

Anthracoblattina,  691,  701 

Anthracomartus,  691,  701;  tri- 
lobitus,  691 ;  Volkelianus,  703 

Anthracomya  carbonaria,  690 ; 
elongata,  690  ;  Isevis,  690 

Anthracopalsemon  gracilis,  678*, 
691 ;  Hillanus,  691 

Anthracosaurus  Russelli,  682,  703 

Anthracotherium,  918,  926 

Anthracothremma  robusta,  691 

Anthrapalaemon  dubius,  703;  Gros- 
sarti,  703 ;  Salteri,  701*,  703 

Anticlines,  102§*,  103*,  109*,  186*, 
368*,  874* 

Anticosti  Island,  shore-platform  of, 
221 ;  Lower  Silurian  in,  493,  533  ; 
Upper  Silurian,  493,  533,  537, 
539,  541,  563,  568,  573;  species 
common  to  the  Clinton  and  Ni- 
agara, 551 

Antilope,  927 

Antimony,  331 

Antipathes,  55 

Antisana(Mt.),26,  296 

Antrim,  867,  938 

Ants,  158,  419,  717,  783,  794 ;  num- 
ber of  Florissant,  901 

Apatemys,  918 

Apateon  pedestris,  704 

Apatichnus  bellus,  752* 

Apatite,  63,  69§,  79,  86,  143,  313, 
447,  450,  453,  455 

Apatornis,  852 

Apatosaurus  laticollis,  763,  764* 

Apennines,  41,  319,  775,  812,  920, 
921,  927,  932 

Aphanapteryx,  1019  ;  Broecki,  1019  ; 
Hawkinsii,  1019 

Aphanitic  texture,  76§ 

Aphelops,  911,  919 

Aphis,  Aphides,  419,  525,  901 

Aphrodina  Tippana,  854 

Apia  Island,  145* 

Apiocrinus,  778;  Meriani,  791; 
Roissyanus,  778*,  779 

Apiocystites  Canadensis,  550  ;  ele- 
gans, 550  ;  Gebhardi,  559* ;  Hu- 
ronensis,  550 

Aporoxylon,  627 

Aporrhais  occidentalis,  984 ;  Sower- 
byi,  925 

Appalachian  Chain,  24,  389,  559, 
734,  743,  798,  799 

—  coal-field,  648 

—  flexures,    102*,    353,   354,    355*, 
356* 

—  geosyncline,  357,  537,   570,   605, 
629,  715 

—  Mountain  Range,  389 ;  character- 
istics of,  353-357 

—  Mountain  System,  389,  732,  883 

—  Mountains,  making  of,  357,  387, 
631,  728,  729,  736 


Appalachian  protaxis,  24,  443*,  444, 
450,  461,  464,  466,  467,  483,  490, 
524,  740 

—  revolution,  728,  735,  877 
Appomattox  formation,  965 

—  group,  892 
Apteryx,  54,  1014 
Aptian  group,  859,  865 
Aptychus  beds,  791 
Apuan  Alps,  fossils  of,  310 
Apus,  486 
Aquamarine,  67§ 
Aquitanian  group,  884,  926 
Arachnids,  418,  419,  420§,  721,  722  ; 

derivation,  722-723 ;  relations  in 
body  segments  and  limbs  to 
Crustaceans,  Limuloids,  and  In- 
sects, 724 

— ,  Upper  Silurian,  557,  574,  721 ; 
Carboniferous,  677,  678*,  691, 
703;  Paleozoic,  721;  Tertiary, 
901,  922 

Arachnophyllum,  552 

Aragonite,  69§,  129,  130,  314,  317 

Aral  Sea,  22,  33 

Aralia,  831,  837 

Aralo-Caspian  depression,  22,  23 

Arapahoe  beds,  827 

Ararat  (Mt.),  296  (height) 

Araucarites,  750,  777 

Arbor  vitas,  435 

Area,  855,  916;  crassicosta,  900*, 
917;  idonea,  917;  incilis,  917; 
inornata,  916 ;  Mississippiensis, 
898*,  916 ;  scalarina,  917  ;  subros- 
trata,  917 

Arcestes,  756,  757 ;  cirratus,  757 ; 
Gabbi,  757,  758  ;  giganto-galeatus, 
774 ;  Nevadensis,  757 ;  ruber,  774 

Archaean,  440 ;  iron  ores  in,  376, 
449 

—  Eozoon,  319 

—  map  of  N.  America,  442,  443* 

—  origin  of  later  rocks,  458 

—  protaxes  of  N.  America,  359, 393, 
457,  531,  744,  746,  812,  826,  875 

—  ranges   of  the  Atlantic   border, 
461 

—  system  of  mountains  in  eastern 
N.  America,  389 

—  of  the  Rocky  Mountain  Chain, 
and  of  the  Front  Range  of  Colo- 
rado, 389 

Archaean  time,  204,  311,  326,  368, 
380,  384,  387,  389,  393,  404,  407, 
409*,  410,  440-459;  N.  America, 
442  ;  foreign,  456  ;  observation's, 
457 ;  age  of,  in  eastern  America, 
466 

Archaelurus,  918 
Archaaocalamites  radiatus,  596* 
Archa?ocidaris,  641,  674,  707;  Nor- 
woodi,   640*,   646 ;    Shumardana, 
626  ;  Wortheni,  640*,  646 
Archaeocyathus  profundus,  470* 
Archaaoniscus  Brodiei,  783* 
Archaeophyton   Newberrianum,  454 
Archaaoplax  signifera,  917 
Archseopteris,  596,  639,  699 ;  Bock- 
schiana,  645;  Browni,  622;  Gas- 
piensis,  611 ;  Halliana,  609*,  622 ; 
Hibernica,   626;  Jacksoni,   595*, 


1042 


INDEX. 


622 ;    minor,   609*,   645 ;  obtusa, 

645;  Kcemeriana,   704;    Kogersi, 

622 

Archaeopteryx,  795 ;  macrura,  788* 
Archseoptilus  ingens,  702 
Archaeoscyphia  Minganensis,  497* 
Archeozoic  scon,  407,  441,  442,  453 
Archegosaurus  Decheni,  708 ;  minor, 

703 

Archidesmus  MacNicoli,  625 
Archimedes,  641 ;  Wortheni,  642*, 

646 

Archimedes  limestones,  637,  646 
Archimylacris,  691 
Architarbus,  701 ;  rotundatus,  691 ; 

subovalis,  703 
Architectonica,  916 
Archiulus,  691,  701 ;  Dawsoni,  691 ; 

euphoberioides,  691 ;  Lyelli,  691 
Archypterygian,  725§ 
Arcoptera  aviculaeformis,  900*,  917 
Arctia,  723 

Arctic  bathymetric  map,  950 
Arctic  border  of  N.  Amer.,  864,  739 

—  emigrant  plants  of  the  Glacial 
period  still  surviving,  945 

—  Ocean,  31,  43,  359,  814,  819,  827, 
857 

—  pole,  17 

—  regions,  climate  of,  256,  524,  792, 
793,  1026 

— ,  Archaean  in,  442  ;  Carbonife- 
rous, 606,  635,  659,  663,  689,  696, 
704,  711;  Cretaceous,  813,  818, 
868,  877,  939  ;  Devonian,  606 ;  Ju- 
rassic, 749,  760,  792,  794  ;  Lower 
Helderberg,  559  ;  Lower  Silurian, 
490,  495,  524;  Mesozoic,  793; 
post-Mesozoic,  874 ;  Niagara,  541, 
544 ;  Paleozoic,  793 ;  Subcarbo- 
niferous,  640,  696 ;  Tertiary,  880, 
933,  939  (plants) ;  Triassic,  792 ; 
Upper  Silurian,  544,  552,  571 

Arctocyon,  925 

Arctomys,  919 

Arctosaurus  Osborni,  749,  792 

Arctotherium  simum,  1000 

Ardea  herodias,  767 

Ardennes,  626,  696,  734 

Areia,  521 

Arenaceous  rocks,  490,  491,  495, 
515 ;  shale,  468 

Arenaria  glabra,  946;  Grb'nlandica, 
946 

Arenicola,  423  ;  marina,  420*,  423 

Arenicolites,  446,  482 

Arenig  group,  517,  518,  520 

Arequipa  Mt.,  274,  296 

Arethusina,  521 

Argentine  Cordillera,  Cretaceous  in, 
867 

—  Republic,  Cambrian  in,  483 
Arges  armatus,  627* 
Argillaceous  rocks,  78§ 
Argillyte,  80§,  84,  89,  371,  408,  531, 

659 

Argonaut,  424 
Argovian,  790 
Argyrocetus,  927 
Argyrosaurus,  867 
Arica,  earthquake  at,  213 
Arionellus,  482 


Aristolochia,  896 

Aristozoe  rotundata,  474* 

Arizona,  23  (height),  135  (agatized 
wood),  187,  300,  541 

— ,  Archaean  in,  449 ;  Cambrian, 
466,  469,  477,  484;  Upper  Silu- 
rian, 541 ;  Devonian,  581 ;  Carbo- 
niferous, 469,  658,  674;  Sub- 
carboniferous,  469  ;  Permian,  660 ; 
Jurassic,  747  ;  Tertiary,  937  (erup- 
tions) 

Arkansas  Hot  Springs,  water  of, 
analyzed,  121;  lead  mines,  842, 
522 ;  novaculite,  80 

—  Canon,  495 

Arkose,  82§,  741 

Armadillo,  54,  1002 

Armorican  sandstone,  521 

Arnioceras  Humboldti,  760 ;  Neva- 
dense,  760;  Nevaduum,  759*; 
Woodhulli,  760 

Arniotites  Vancouverensis,  758 

Arsenopyrite,  70§ 

Artesian  borings  (wells),  120,  207*§, 
257,  522,  742,  889,  890 

Arthroclema  Billingsi,  506*;  cor- 
nutum,  506* 

Arthrolycosa  antiqua,  678*,  691 

Arthrophycus  Harlani,  549 

Arthropods,  141,  419,  423,  455,  469 

Articulates,  141,  409*,  418,  419, 420*, 
437,  439,  674,  7lt,  720,  783* 

Artiodactyls,  906§,  907,  909,  910, 
911*,  918,  919,  924,  927,  928,  930 

Artisia,  673 

Artocarpus  Lessigiana,  839 

Arum  family,  777 

Arvonian  period,  446,  457 

Asaphus,  422§,  482,  488,  500,  502, 
508,  516,  521,  551 ;  Canadensis, 
516,  canalis,  503,  517;  Homfrayi, 
520  ;  marginalis,  503 ;  megistos, 
422,  512,  551 ;  obtusus,  503 ;  platy- 
cephalus,  422,  508*,  512,  515,  516 ; 
Powisi,  519,  520*;  tyrannus,  520 

Asbestos,  67§,  319 

Ascension  Island,  volcano  of,  290, 297 

Ascidians,  55,  418,  725 

Ascoceras,  551;  Canadense,  573; 
Newberryi,  551,  573 

Ash  beds,  80§ 

—  of  coal,  661,  662,  663,  664 

—  of  plants,  73,  74,  75 ;    see  also 
Volcanic  ashes 

Ashley  beds  (marl),   888,  891,  917 

Asia  (see  also  Eurasia),  19,  22,  23, 

24,  31,  32*,  33,  34,  40,  41,  50,  165, 

393,  394,  395,  398,  406,  737,  871,  938 

— ,  Carboniferous  in,  632,  693,  700  ; 

Lower     Silurian,     521 ;      Upper 

Silurian,  563  ;  Triassic,  632,  741 ; 

Cretaceous,    867;    Tertiary,  365, 

919,  933,   936,   939;    Quaternary, 

950 

— ,  eastern,  island  chains,  40 
Asia    Minor,    296  (volcanoes),  920 

(Eocene) 

Aso-san  (Mt.),  277 
Asphalt,  74 

Aspidella  Terra-novica,  446 
Aspidium  Dunkeri,  831;  filix,  74; 
Lakesii.  839 


Aspidoceras,  794 

Aspidorhynchus,  784* 

Asplenium  erosum,  889 ;  filix,  74 

Ass,  55 

Assat  Lake,  200 

Astacus,  783 

Astarte,  780 ;  annosa,  837 ;  Banksii, 
983,  984 ;  borealis,  984,  995 ;  com- 
pressa,  791;  elliptica,  983 ;  gre- 
garia,  790 ;  Laurentiana,  984 ; 
minima,  780*,  790 ;  obliqua,  790  ; 
obovata,  867 ;  protracta,  916 ; 
Smithvillensis,  916;  supracoral- 
lina,  790 ;  undulata,  917 ;  veta, 
837;  vicina,  917 

Astartian  group,  790 

Asterias  arenicola,  994 

Asterioids,  428§,  429*  ;  Lower  Silu- 
rian, number  in  Great  Britain,  521 

Asterochlsena  Noveboracensis,  610 

Asterolepids,  417 

Asterolepis,  625,  626,  627 

Asterophyllites,  639,  671,  699,  704  ; 
acicularis,  622 ;  elegans,  699 ; 
equisetiformis,  645,  671*,  689 ; 
foliosus,  689;  latifolius,  596*, 
622 ;  sublams,  671*,  689 

Asteropteris  Noveboracensis,  610 

Asthenodon  segnis,  767* 

Astian  group,  927 

Astoria,  Oregon,  sandstone  veins, 
344*  ;  sandstones  and  shales,  892 

Astoria  clay-shales  in  Washington, 
892 

Astraea  distorta,  791 

Astraeospongia,  550,  584,  590 ;  men- 
iscus, 550 

Astral  aeon,  440 

Astraspis  desiderata,  509* 

Astrocerium  venustum,  550 

Astrocoenia,  777,  778  (number  of 
British) 

Astrodon  Johnstonii,  836 

Astylospongia,  515,  550;  parvula, 
513 ;  Eoemeri,  503 

Asymptoceras  capax,  691;  Newtoni, 
691 

Atacarna  desert,  51 

Atacamite,  335 

Atane  group,  831,  837,  838,  839,  872 

Atanekerdluk  series,  921 

Athabasca  Lake,  29 

Athrodon,  789* 

Athyris,  642 ;  angelica,  592,  621  ; 
concentrica,  426*,  626,  627 ;  la- 
mellosa,  700*  ;  spiriferoides,  598*, 
601 ;  subtilita,  675*,  685,  704,  711 

Atiu  Island,  elevation,  350 

Atlantic  City  boring,  378 

—  coast  of  N.  Amer.,  948  (fiords) ; 
subsidence  in  progress,  350 

—  division  of  Archaean  rocks,  446 

—  Ocean,  17,  19  (depth),  20,  21,  31, 
34,  40,  42,  43,  46  (temperature), 
47*,    48,   49,    121    (salinity),    230 
(bottom),  252,  256,  354,  391,  394, 
536,  587,  793  ;  volcanoes  in,  297 

— ,  currents,  43,  44,  45,  46,  47*, 
48,  256 

—  and  Pacific  in  Lower  Cretace- 
ous united  over  Mexico,  814,  818 
Atlantis,  506 


INDEX. 


1043 


Atlantis  of  fable,  20,  217 
Atlantochelys  Mortoni,  849 
Atlantosaurus  immanis,  764 
Atlantosaurus  beds,  748,  758,  760, 

761,  766,  767,  768,  776 
Atlas  Mts.,  33 
Atmosphere,  63§ ;  currents  of,  49 ; 

weight  of,  158 

—  as  a  mechanical  agent,  118, 158- 
165 

— ,  carbonic  acid  in,  128,  727 
— ,  estimated  limit,  16,  158 ;  varia- 
tions in  density,  256 

—  of  the  Carbonic  era,  711 ;  Paleo- 
zoic, 727 

Atmospheric  dust,  118 

Atolls,  145*§,  146,  147,  148,  149*, 
150,  151,  221,  227,  350,  664 

Atractites,  757  ;  secundus,  774 

Atretia,  59 

Atrypa,  436*§,  520,  552,  562,  612  ; 
aspera,  590,  591,  598*,  601,  602, 
625;  comata,  568;  desquamata, 
628;  hemisphserica,  550;  hystrix, 
613*  ;  imbricata,  520 ;  .impressa, 
590 ;  laevis,  625 ;  navicula,  568  ;  no- 
dostriata,  548*,  551  ;  oblata,  549  ; 
occidentals,  590 ;  reticularis,  426*, 
522,  546*,  550,  551,  552,  562,  567, 
568,  569,  572,  590,  591,  592,  598*, 
601,  602,  612,  620,  625,  626,  627, 
628  ;  rugosa,  551 

Atrypina  disparilis,  548*,  551 

Aturia  ziczac,  925 

Aublysodon,  856 ;  mirandus,  856 

Aubrey  limestone,  658;  sandstone, 
658 

Aucella,  748,  749,  760,  794,  809,  818, 
834,  835,  837  ;  Erringtoni,  759* ; 
gryphaeoides,  865  ;  Piochii,  &34, 
835* 

Aucella  beds,  748,  776 

Auchenapsis,  625 

Auchenia  major,  1001 ;  minor,  1001 

Auckland  Islands,  37 

Augite,  67*§,  85,  86,  87,  88,  295,  324 

—  andesyte,  87§,  265,  324 

—  dioryte,  86§,  266 

—  granite,  85§ 

—  quartz-syenyte,  85§ 

—  syenyte,  85§,  317 
Augitic  rocks,  89,  309,  371,  449 
Augitophyric,  77§ 
Aulacoceras  Carlottensis,  758 
Aulopora,  550,  562,  621 ;  precia,  550 ; 

repens,  550 ;  tubiformis,  628 

Auriferous  belt,  of  the  Sierra,  809 

Aurochs,  927,  1006 

Auroral  group  of  Kogers,  490,  728 

Austin  limestone,  815,  817,  824,  855 

Austin-Dallas  chalk,  824 

Australasian  chain  of  islands,  37, 
38,  39*,  40 

Australia,  17,  19.  21,  22,  34  (system 
of  reliefs),  39,  51,  53  (animal  char- 
acteristics), 148  &  151  (reefs), 
153,  346  (sea  level  at  center), 
394,  395,  398,  406,  415,  418,  687, 
715,  797,  798,  838,  869,  874  (con- 
nection with  S.  A'frica),  921,  948 
(fiords) ;  related  in  species  of 
birds  to  New  Zealand,  1019 


Australia,  Cambrian  in,  483  ;  Lower 
Silurian,  522 ;  Upper  Silurian,  563, 
564;  Devonian,  628;  Carbonic, 
632,  693  ;  Permian,  632,  698,  737 ; 
Triassic,  632,  699,  791,  797-798* ; 
Jurassic,  699,  770,  776,  791,  792; 
Cretaceous,  887;  Tertiary,  937; 
Glacial,  948 

Australian  Alps,  34,  380 

—  types  in  Europe,  922,  939 
Austria,   Upper    Silurian    in,  573; 

Subcarboniferous,  698  ;  Carbon- 
iferous, 693,  696;  Permian,  698; 
Triassic,  755,  768,  769  ;  Jurassic, 
774;  Cretaceous,  857,  859,  864; 
Tertiary,  926,  927 

Austro-Russian  Cretaceous  basin, 
857 

Auvergne,  26,  274,  297  (volcanoes), 
922,  938  (eruptions) 

Aux  vases  sandstone,  638 

Avalanche,  233§,  247 

Avalon,  446 

Avicula,  525,  549,  585,  756,  916; 
contorta,  770,  771*,  774 ;  demissa, 
511*,  516;  echinata,  791;  emace- 
rata,  548*,  550,  551 ;  exilis,  774 ; 
expansa,  790  ;  Homfrayi,  757 ; 
insequivalvis,  790  ;  Kazanensis, 
707 ;  linguiformis,  855  ;  longa, 
690  ;  Munsteri,  791 ;  naviformis, 
562;  obscura,  558;  ovalis,  790; 
rhomboidea,  546*,  550 

Avicula  contorta  beds,  769 

Avicula  family,  840 

Aviculoides  labiatus,  855 

Aviculopecten,  562,  602,  620,  621  ; 
altus,  757, ;  amplus,  647  ;  Burling- 
tonensis,  647 ;  duplicatus,  613*, 
621 ;  Idahoensis,  757  ;  oblongus, 
647  ;  Oweni,  647  ;  Pealsi,  757 ; 
princeps,  602 ;  rectilaterarius,  690 

Axinaea,  916 

Axinite,  310 

Axinus  angulatus,  925 

Aymestry  limestone,  563,  567,  568 

Azof  Sea,  857 

Azoic,  440,  468 

Azores,  41,  297  (volcanoes),  308 
(geysers) 

Bacillaria  paradoxa,  437* 

Bacteria,  52,  136-137,  436,  441,  454 

Bactrites,  621 ;  acicula,  613*,  621 ; 
clavus,  599 ;  gracilis,  627 

Baculites,  843§,  856 ;  anceps,  854, 
855,  867;  annulatus,  855;  asper, 
855;  Chicoensis,  831;  compressus, 
842*,  843,  854,  855 ;  Faujasi,  866 ; 
grandis,  855;  ovatus,  842*,  854, 
855;  Spillmani,  855;  Tippoensis, 
855. 

Bad  Lands,  893,  894 

Badiotites,  757 ;  Carlottensis,  758 

Baffin  Bay,  40,  44,  252  (icebergs), 
444 

—  Land,  444 

Bagshot    beds    (sands),    920,    925, 

926 

Bahamas,  162,  163,  213 
Bahian  group,  867 
Bahio  Glacier,  240 


Baiera,  685,  693,  750  ;  digitata,  705 ; 

longifolia,  833  ;  Virginiana,  705 
Baikal  (.Lake),  33,  200 
Bajocian  group,  775,  790 
Baker  (Mt.),  296  (height) 

—  Island,    changes  in    position    of 
beach,  225* 

Bakewellia  antiqua,  707 ;  parva, 
685* 

Bala  group,  517,  518,  520,  569  ;  lime- 
stone, 519 

Bala?na,  144 

Batenoptera,  144 

Balatonites  Vancouverensis,  758 

Bald  Mt.,  467,  473,  495,  496,  527, 
528* 

Baleen  Whales,  912,  925 

Balkan  peninsula,  793 

Ball  ore,  664 

Ballston  Springs,  analysis,  121 

Baltic  provinces,  768,  794 

—  Sea,  41,  121  (salinity) 
Baluchistan  earthquake,  375 
Bandai-san  eruption,  293 
Banks  Land,  635 
Baphetes  planiceps,  682,  692 
Baptanodon  beds,  748,  758,  760 
Baptanodon  discus,  761* 
Baptoruis,  852 

Baptosaurus  fraternus,  848 ;  platy- 

sphondylus,  848 
Baraboo  quartzyte,  468 
Barbados,  163,  433,  935,  936 
Barbatia  parva  Missouriensis,  836 
Baring  Isl.,  659 
Barite,  69§,  143,  331,  333,  342,  493, 

745 

Barium  sulphate.     See  Barite 
Bark,  composition  of,  713 
Barnacles,  157,  421  §,  513  ;  Cornifer- 

ous,  586,  587;    Hamilton,  600*; 

Lower  Silurian,  496,  720 ;  Paleo- 
zoic, 720 

Baropus  lentus,  684* 
Barornis  regens,  902 
Barrandia,  520,  521 
Barren  (Lower)  Measures,  634,  648, 

651-652,  656,  657,  677 
Barren  (Upper)  Measures,  634,  648, 

651,  657,  660 

—  See  also  Permian  period 
Barrier  reefs,  14S*§,  149*,  150*,  151, 

227,  541,  713 

Barriers,  sand,  of  coasts,  223,  224* 
Barrow  (Point),  640 
Barrow  Strait,  544,  552 
Barton  clay  (series),  925/926 

—  coal-bed",  652 
Bartonian  group,  925 
Barycrinus,  138 
Baryta,  Barytes,  69§ 

Basalt,  16,  67,  87§,  134,  259,  288* 
|   Basaltic  columns,  261*§,  262*,  263, 

274 

Basement  Complex,  458 
Basic  igneous  rocks,  64,  65§,  86, 273, 

938 

Basilosaurus,  908 
Bat.    See  Bats 
Bat  guano,  153 
Bath  Oolyte.     See  Oolyte 
Bathonian  group,  775,  790 


1044 


INDEX. 


Bathurst,  N.B.,350 

—  Land,  659,  749,  792 
Bathyactis  symmetrica,  57 
Bathycrinus,  59 
Bathygnathus    borealis,    741,    753, 

754* 

Bathylite,  bathylith,  811  §,  938 
Bathymetric  map  of  the  Pacific  and 

Atlantic,  following.  20 

—  of  the  Arctic  Ocean,  950 

—  of  the  Atlantic  border  of  New 
Jersey,  Long  Island,  etc.,  18 

Bathynoinus  giganteus,  59 

Bathynotus  holopyga,  473* 

Bathyopsis,  918 

Bathyurellus,  500,  503  ;  nitidus,  501* 

Bathyuriscus  Howelli,  476* 

Bathyurus,  500 ;  Angelini,  503,  517  ; 
arinatus,  501 ;  conicus,  517 ;  cro- 
talifrons,  501*  ;  extans,  517  ;  Saf- 
fordi,  501*,  517 

Batocrinus,  641,  646 ;  Christyi,  640*, 
646 ;  longirostris,  428*,  430§,  640*, 
646 

Batodon  tenuis,  853* 

Bats,  53,  54,  153,  415,  721,  797,  907, 
910,  924,  926 

Batscham,  tide  at,  211 

Bavaria,  26,  453 

— ,  Archaean  in,  453,  454,  456  ;  Cre- 
taceous, 857 ;  Jurassic,  774,  776 

Bay  of  Biscay,  377 

—  of  Fundy,  210  (tides),  350,  444, 
461,  536,  741 

—  of  Plenty,  374 

Beach  formations,  94,  95,  151,  202, 

222,  223 ;  structure,  93§,  99,  222 
Bear  Island,  635,  704 

—  Kiver  coal-beds,  825,  839 
Beauchamp  sands,  925 
Beaufort  beds,  699,  707,  770 
Beaver  Kiver,  947 

Beavers,  55,  904,  911,  927,  950  (mi- 
gration) 

Becrafts  Mt.,  531,  552,  558,  559, 577, 
578,  579 

Beds,  76§,  91§,  92  (kinds) 

—  of  ore.    See  Ore-beds 

—  of  sand,   mud,  limestone,    etc., 
simultaneously  in  progress,  399 

Beech,  812,  837,  922 

Beehive  Geyser,  307*,  308* 

Beemerville  rock,  532 

Beetles,  419,  679,  702,  721,  722,  771, 

887 

Beggiatoa,  137 
Bela  exarata,  984;  harpularia,  984; 

robusta,  984 ;  turricula,  984 
Belcher  Expedition,  792 
Belemnitella  Americana,  842*,  854 ; 

bulbosa,    855;    mucronata,    855, 

866 ;  plena,  866 ;  quadrata,  866 
Belemnites   appressus,  835;    cana- 

liculatus,  791 ;  clavatus,  790,  791 ; 

densus,  758*,  760  ;  hastatus,  790 ; 

jaculum,   865;    Nevadensis,   760; 

niger,  760 ;  Oweni,  790 ;  Paciflcus, 

760;   paxillosus,   760,    782*,  790; 

vulgaris,  790 

Belemnoteuthis,  782;  antiqua,  782* 
Belgium,  Carboniferous  in,  693,  696, 

768;    Cretaceous,   848,   859,   863; 


Paleozoic,  463  ;  Tertiary,  920,  921, 

925,  926  ;  Upper  Silurian,  568,  569 
Belinurus,  701,  720 ;  arcuatus,  703 ; 

Reginse,  703 ;  trilobitoides,  703 
Belle  Isle,  467  ;  Strait  of,  793,  873 
Bellerophon  antiquatus,  478*  ;  bilo- 

batus,  507*,  514,  520,  521,  550, 569  ; 

Cambrensis,     481 ;     carbonarius, 

675*,  690  ;  carinatus,  520,  567,  573 ; 

cyrtolites,    647;    dilatatus,    567; 

expansus,  573 ;  maera,  592,  613* ; 

natator,  620  ;  nodosus,  520 ;  patu- 

lus,  602;    trilobatus,   567;    Urii, 

690,  711 

Bellerophon  limestone,  660 
Bell's  Landing  beds,  888 
Belly  Kiver  group,  830  ;  region,  825 

(coal),  880 
Belodon,    754,    758;    Carolinensis, 

754*;  priscus,  754* 
Belodonts,  772,  773 
Belceil  Mt.,  531 
Belosepia    sepioidea,   925;    ungula, 

897*,  916 

Beluga  Vermontana,  983 
Bembridge  beds,  926 
Beneckia  Buchii,  773 
Bengal  coal-beds,  698 
Benton  group,  815,  829,  850 
Benzine,  74 
Berea  grit,  608 
Bergkalk,  632 
Bering  Sea,  43 ;  Strait,  43,  48,  257, 

877,  950  (dry  ?) 
Bermuda  Islands,  20,  46,  145,  162, 

218,  224 

Bernardston,  Mass.,  310,  825 
Bernician  group,  695 
Beryl,  67§,  69,  332,  336 
Beryllia,  67 

Beryx,  862 ;  insculptus,  843 
Besano  dolomyte,  774 
Betulji,  840 
Beverly  Island,  39 
Beyrichia,  516,  562,  567,  643 ;  bella, 

515  ;1ata,  562 ;  spinosa,  550 ;  sym- 
metrica, 549*,  550;  trisulcata,  558; 

tuberculata,  568 
Big  Cotton  wood  Canon,  476,  495 

—  Horn  basin,  893,  906 

—  Horn  Mts.,  266,  478,  748,  830 
Billingsella   festinata,  471*;    gran- 

dseva,  499*,  500 ;  orientalis,  471* 
Bilobites,  474,  546 ;  bilobus,  551 
Biotite,    65§,    83,   85,   86,   87,  318, 

320 

—  gneiss,  83 ;  granites,  82  ;  mica, 
320 

Birch,  837 

Bird  of  paradise,  54 

Birds,  141,  163,  414,  415,  721,  752, 
786,  789,  794,  795,  796,  877,  879, 
914 

— ,  Triassic,  794 ;  Jurassic,  767, 776, 
783,  788*,  795,  796,  852,  871 ;  Cre- 
taceous, 812,  850*,  851*,  852,  864, 
870,  871  ;  Tertiary,  883,  893,  902, 
921,  923,  925 

Birdseye  limestone,  489,  492,  493, 
494,  503,  505,  515 

Bismuth,  331 

Bison  Americanus,  1001 ;  antiquus, 


1002,  crassicornis,  1002;  latifrons, 
999 ;  priscus,  1015 

Bitter  Creek  group,  886 

Bittern,  120§ 

Bittium  Chipolanum,  917 

Bitumen,  337,  581,  593 

Bituminous  coal,  74,  124,  649,  655*, 
661,  695,  714,  731,  741,  825  ;  analy- 
ses, 485,  662,  6C8,  664,  712,  713 

Black  Bluff  beds,  888 

Black  Dome,  27 

—  Forest,  698,  734 

—  Hills,    830;    Archaean    in,    444; 
Cambrian,    469;     Niagara,    541, 
543;   Carboniferous,  658;   Trias- 
sic, 746,  747 ;  Jurassic,  747,  748, 
758,   760;    Cretaceous,    818,   827, 
829,  832,  843 

Black  lead,  62§ 

Black    River   limestone,  489,    492, 

494,  503,  506,  513,  514,  515 
Black  Sea,  22,  857 
Blackfoot  Basin,  747 
Blake  plateau,  230 
Blanching  of  rocks,  etc.,  134,  822 
Blanco  group,   884,   885,   895,   912, 

919 

Blastoidocrinus  carcharidens,  503 
Blastoids,   430§,    547*,    548  (first), 

585*  590,  641,  646 
Blastomeryx,  911,  919 
Blattariaa,  757 
Bleaching.     See  Blanching 
Blende,  70§,  333,  493 
Block  coal,  661,  662 
Block  Island,  852 
Blood  rains,  163§,  165 
Bloomsbury  conglomerate,  594 
Blowing-cone,  279§,  284 
Blue  limestone  of  Owen,  494,  516, 

728 

—  or  Maclurea  limestone  of  Safford, 
494 

Blue  Mts.,  Australia,  34 

Blue  Mts.,  N.J.,  532 

Blue  Mts.,  Oregon,  748,   749,  811, 

'    830 

Blue  Ridge,  468,  745 

Bluestone,  593 

Boa  constrictor,  156 

Boavus,  901 

Bob,  Mt.,  552,  558 

Bodie  Mt.,  auriferous  veins  of,  334 

Bog-head  cannel,  662 

Bog  ore,  128,  129,  708 

Bohemia,  upturnings  in,  630,  734 

— ,  Archaean  in,  455,  456 ;  Cambrian, 
482,  518;  Lower  Silurian,  518, 
521 ;  Upper  Silurian,  563 ;  Car- 
boniferous, 696,  703,  723;  Trias- 
sic, 768;  Cretaceous,  838;  Ter- 
tiary, 938  (eruptions) 

Bohemian  formation,  535 

Bohemilla,  521 

Bolderian  beds,  926 

Bolivia,  26  (plateau),  41,  296  (volca- 
noes), 627,  628,  711 

Bolodon,  789* 

Bolonian,  791 

Bombay,  299 

Bombs,  volcanic,  287*§,  289 

Bone-beds,   Quaternary,  892  ;  Ter- 


INDEX. 


1045 


tiary,    902;    Triassic,    769,    774; 

Upper  Silurian,  563 
Bones,  63§,  72,  73  (analyses),  141, 

143,  144,  153,  162,  190 
Bonneville  Lake,  G.  K.  Gilbert  on, 

202,  382 

Bony  coal-bed,  656 
Boothia  Felix,  495 
Boracic  acid,  63,  66,  813 
Boracite,  320 
Borate  springs,  313 
Borates,  119,  137,  320 
Borax,  63§ 
—  Lake,  siliceous  deposits,  323,  334, 

335 

Boring  animals,  157,  425 
Borneo,  40,  297,  696 
Bornia  inornata,  610;   transitionis, 

699 

Bornite,  335,  745 
Boron,  63,  320,  335 ;  salts,  320 
Borophagus,  919 
Borsonia  biconica,  916 
Bos,  927  ;  Americanus,  1016 ;   pri- 

migenius,  1006,  1016 ;  Urus,  1016 
Boston  basin,  732 
Bothriolabis,  918 
Bothriolepis,   616*,   617,   619,    625; 

Canadensis,    616*,    617 ;    minor, 

621 ;  nitida,  621 
Botryoconus,  689  ;  Pitcairnise,  673*, 

674 ;  priscus,  673*,  674 
Bottom-lands,  181  § 
Bourbon,  Isle  of,  296  (volcanoes) 
Bourbonne-les-Bains,  thermal    wa- 
ters at,  335 
Bourgogne,  769 
Bow  River  region,  826  (coal) 
Bowlder  clay,  81§,  251§ 
Bowlders,   81,  127*,  664  (in  coal) ; 

see  Glacier  Drift. 
Brachiates     (Brachiate     Crinoids), 

429§ 
Brachiopods,   59,    60,   425*§,    426*, 

427*  ;  articulate  and  inarticulate, 

425§,  471 
Brachiospongia,  515 ;  digitata,  504*, 

513 ;  Roemerana,  513 
Brachymetopus,  676,  700 
Brachypsalis,  919 
Brachyurans,  59,  420§,  438§439,  707, 

720 

Bracklesham  beds,  923 
Bradfordian,  790 
Branchiates,  419§ 
Branchiosaurus,  706 
Branchiostoma,  418§ 
Branchville  granitic  veins,  326 
Brandon,  Vt.,  lignite  bed,  887,  895 
Brandschiefer,  80§ 
Brazil,  31  (mountains),  184;  Archaean 

in,  456;  Carboniferous,  659,  687; 

Devonian,    627 ;    Jurassic,    776 ; 

Cretaceous,  857,  858,  867 
Breaks  in  the  geological  record,  406, 

488 

Breccia,  80§ 
Brecciated  vein,  330§ 
Brick-clay,  81  § 
Bricks    from    the    depths    of    the 

Atlantic,  230 
Bridgeman's  Island,  296  (volcanoes) 


Bridger  group  (beds),  884,  886,  893, 
901,  904,  905,  907,  918,  923,  925 

—  Lake  (basin),  882,  893 
Brier  Hill  coal,  657,  662 
Brine  springs,  120 
Brines.    See  Salt 

British  Channel,  16,  210,  936 

—  Columbia,  25,  389,  390,  812,  948 
(fiords);     Cambrian,    476,     477; 
Carboniferous,  659,  674 ;  Triassic, 
746,  757 ;  Triassic  and  Jurassic, 
739,   809;  Cretaceous,   818,  868; 
Glacial,  945,  948  ;  Quaternary,  950 

Brittany  united  with  Cornwall,  936 

Broad  Top,  649,  659 

Bromides,  63,  335,  341 

Bromine,  63,  120,  331 

Bromo-chloride,  340 

Bronteus,  552,   561,  562,  568,  599, 

625,  626 ;  grandis,  627 ;  pompilius, 

561*  ;  Tullius,  599 
Brontops,  918 ;  robustus,  909* 
Brontosaurus  excelsus,  763* 
Brontotherium,  914*,  918 
Brontotherium  beds,  886 
Brontozoum  giganteum,  752* 
Bronzite,  67§,  136 
Brooklyn,  N.Y.,  water  supply  of, 

206 

Brookville  coal,  652 
Brown  coal,  74,  662,  712,  713,  714, 

920,  922 

Brown's  Park  group,  886 
Brownstone,  746 
Brunswick,  769 
Bryozoans,  141,  142,  147,  418,  419, 

425*,  427§* 
Bubo  leptosteus,  902 
Bucania,  503,  521,  562;  rotundata, 

502*  ;  sulcata,  503  ;  trilobata,  544*, 

549,550 
Buccinum  Groenlandicum,  984,  995 ; 

undatum,  984 
Buchiceras    inaequiplicatum,    837  ; 

pedernale,  836  ;  Swallovi,  854 
Buck  Mountain  coal-bed,  656 
Buckingham  (Va.)  Triassic  area,  741 
Buckler,  421  § 
Buff  limestone,  494 
Buhrstone,  82§,  885,  888§,  889,  890 
Bulimus  ellipticus,  926 
Bulk,     changes     of,    in     mineral 

changes,  134,  138,  453,  523 
Bulla,  916  ;  speciosa,  841* 
Bullinella  Jacksonensis,  916 
Bumelia,  922 
Bunselurus,  918 
Bunker  Hill  Monument,  260 
Buntersandstein,  411,  738,  769 
Buprestids,  771 
Buprestis,  783*  (wing-case) 
Burdigalian  group,  926 
Burlington  group,  634,  637,  638 

—  limestone,  646  (Crinoids),  647 
Burnetan,  446 

Busycon  Bairdii,  855 
Buthotrephis,  544;    gracilis,   504*, 

549  ;    Harknessi,  519*  ;    ramosa, 

549 ;  succulens,  504* 
Butterflies,  54,  419,  679;  Tertiary, 

202,  887,  900* 
Byam  Martin  Isl.,  659 


Byssoarca  protracta,  916 
Byssus,  424§ 

Cadaliosaurus,  706 

Cadent  series,  728 

Cadomella,  790 ;  Moorei,  779* 

Cadulus  turgidus,  915 

Caenopus,  918 

Caerfai  group,  481 

Caesium,  335,  449 

Cahaba  coal-fields,  657 

Cainozoic.     See  Cenozoic 

Caithness  flags,  623 

Caking  coal,  661,  662  (analyses) 

Calabria,  earthquake  in  1783,  375 

Calais  united  with  England,  936 

Calamary,  424* 

Calamine,  342 

Calamites,  627,  629,  671,  699,  704, 
718;  approximate,  654,  689; 
arenaceus,  774 ;  cannaeformis, 
622,  671*,  689 ;  Cistii,  689  ;  radi- 
atus,  622,  626,  704;  ramosus, 
689  ;  Suckovi,  645,  654,  685,  689, 
692,  704 

Calamitids,  689 

Calamodendron,  699,  718 

Calamodon,  917,  918 

Calamopora  spongites,  310 

Calamopsis  Danse,  895*,  896 

Calamus,  435 

Calaveras  skull,  1012 

Calcaire  carbonifere,  632 

—  conchy  lien,  769 

—  grossier,  205,  884,  920,  923,  924, 
925,  926 

Calcareous  deposits,  131,  132*,  133, 
152-153;  fossils,  129,  130,  314; 
organic  rock-material,  72§,  134, 
140,  144,  487,  496 ;  rocks,  78§-80 ; 
sponges,  431  § 

—  waters,  305  ;    consolidation  by, 
133 

Calceocrinus  Barrandei,  514 
Calceola  sandalina,  427*,  626,  627 
Calceola  slates,  626,  627 
Calciferous  epoch,  490,  491 

—  limestone  group,  695 

—  sandrock,  45*,  490,  500 
Calcispongiae,  431§ 
Calcite,  15  (density),  68§* 
Calcium,  61,  67;  bicarbonate,  122, 

129  ;  borate,  120 ;  carbonate,  62§ ; 
chloride,  119,  120;  fluoride,  73, 
121  (see  also  Fluorite) ;  iodide, 
120 :  calcium-magnesium  carbon- 
ate (see  Dolomite)  ;  nitrate,  137  ; 
phosphate,  63§  (Apatite);  sul- 
phate, 72,  73  ;  sulphide,  125 

Calcyte,  79§,  316,  321,  490;  con- 
verted to  dolomyte  with  dimin- 
ished bulk,  134,  523 

California,  18,  23  (height),  25,29; 
silicified  forests  of,  135;  Diatom 
bed,  152 ;  Salton  Lake,  200 ;  vol- 
canoes of,  296 ;  Table  Mtn.,  300  ; 
Borax  Lake,  323 

— ,  Archaean  in,  444 ;  Silurian,  809  ; 
Devonian,  580,  592 ;  Carbonifer- 
ous, 659,  674 ;  Triassic,  746,  757, 
809,  810 ;  Jura-Trias,  749 ;  Juras- 
sic, 748,  749,  759,  760,  809; 


1046 


INDEX. 


Cretaceous,  317,  318,  325,  811, 
818,  820,  830,  834,  837,  840,  868 
(subsidence) ;  Tertiary,  831,  884, 
885,  888,  891,  892,  895,  916,  932, 
937 ;  Glacial,  949  ;  Quaternary, 
950 

Caligus,  420 

Callipteridium,  685,  693,  699 

Callipteris,  685,  693,  699;  conferta, 
704 ;  pilosa,  622 

Callitris,  922 

Callocystites  Jewetti,  429*,  547, 
550 

Callovian  group,  760,  775,  776,  780, 
790 

Caloosahatchie  beds,  890 

—  River,  892 

Calophyllum,  552 

Calopodus,  692 

Calumet  mine,  339 

Calvert  Cliffs,  891 

Calymene,  810,  422,  520,  521,  546, 
551 ;  Allportiana,  520 ;  Blumen- 
bachii,  420*,  421,  520, 551,  552,  562, 
567,  568,  586;  callicephala,  508*, 
509,  512,  515,  524,  549,  550; 
Christyi,  516;  Clintoni,  550; 
Niagarensis,  549,  550,  551;  pla- 
tys,  591  (last  American  species)  ; 
tuberculosa,  551,  567,  569 

Calyptraea,  475 

Camaphoria  subtrigona,  646 

Camarella  antiquata,  471*  ;  calcifera, 
500 ;  congesta,  550  ;  longirostris, 
503 ;  primordialis,  478*  ;  varians, 
500,503 

Camarocrinus  Saffordi,  550;  stel- 
latus,  558 

Camarophoria,  707  (ends  in  Per- 
mian);  crurnena,  707;  formosa, 
627;  Humbletonensis,704;  Schlot- 
heimi,  707  ;  superstes,  707 

Cambrian  and  Silurian,  history  of 
the  terms,  463,  464§,  489 

Cambrian,  462;  American,  464; 
foreign,  480 

Cambric.     See  Cambrian 

Cambridge  Greensand,  863,  864 

Camel,  54,  55,  907,  910,  911,  912, 
919,  928 

Camelopardalis,  54,  927 

Camelus,  927 

Cameroons  Mts.,  295,  297  (height) 

Campanian,  859,  866 

Campbell  Island,  89 

Campophyllum  torquium,  690 

Camptonectes  bellistriatus,  760 

Camptonyte,  87§ 

Camptopteris,  756 

Camptosaurus  dispar,  764,«  765*; 
medius,  765* 

Campylodiscus  clypeus,  163,  164* 

Canada,  24,  26,  78,  258 

— ,  Archaean  in,  443 ;  Cambrian, 
464,  466,  476,  479,  496;  Calcifer- 
ous,  491,  492,  493,  496,  497,  499, 
500,  501;  Chazy,  491,  493,  503; 
Trenton,  493  ;  Clinton,  542  ;  Me- 
dina, 539,  542;  Niagara,  540, 
543,  544,  549,  551 ;  Devonian, 
576,  581,  591,  611,  628,  630; 
Corniferous,  580,  581,  590,  591  ; 


Carboniferous,  453,  581 ;  Creta- 
ceous, 825,  830,  840,  872;  Ter- 
tiary, 918 

Canada  Bay,  467 

Canadian  Pacific  R.R.,  26,  859 

—  period,  491 

—  River,  29 

Canary  Islands,  20,  41,  207 

Cancer,  420* 

Cancrinite,  85,  449 

Canimartes,  919 

Canis,  911,  919, 927 ;  Parisiensis,  924 

Canistrocrinus,  516 

Cannapora  junciformis,  550 

Cannel  coal,  654,  661,  662  (analyses), 
692,  710  (formation),  714 

Cap  au  Gres,  732 

Cape  Breton,  Cambrian  in,  476 ; 
Carboniferous,  691 ;  Coal-meas- 
ures, 658,  678 

Cape  Cod,  160,  873,  881,  916 

—  Dundas,  659 

—  Girardeau  limestone,  559 

—  Hatteras,  18,  43,  45,  48,  210,  224*, 
793,  823,  878,  949 

—  Horn,  21,  23,  858 

—  of  Good  Hope,  21 

—  Verd  Islands,  297 
Capelin,  984 

Caprina,  820 ;  adversa,  866  ;  anguis, 
886 ;  Texana,  834,  835* 

Caprina  limestone,  817,  886 

Capulus,  471,  482,  574 

Carabocrinus,  516 

Caradoc  group,  463,  518,  534 ;  sand- 
stone, 520,  584 

Carbon,  61,  62§ ;  Archaean,  453,  454 

—  Ridge,  733 
Carbonaceous  clay,  81§ 

—  rock-material,  74§,  140,  141,  153- 
155,  315  (metamorphic  changes), 
819,453 

—  shale,  80§ 

Carbonate  of  lime.    See  Calcite. 

—  of  magnesia,  69 
Carbonates,  68 

Carbonic  acid,  62,  128-185;  in 
Archaean,  440,  441,  442,  450,  451, 
454;  in  Cambrian  atmosphere, 
485;  at  beginning  of  Carbonic 
era,  711,  712 ;  constructive  effects, 
181;  destructive,  129;  in  geyser 
region,  309 ;  from  respiration, 
136 ;  from  volcanoes,  128,  278 

Carbonic  era,  631 ;  American,  633 ; 
foreign,  693;  formation  of  coal, 
712 ;  economical  products,  661- 
665 

Carbonic  oxide,  278  (from  Kil- 
auea),  523,  661 

Carboniferous  age,  631 

Carboniferous  period,  647 

Carcharias,  863 

Carcharodon,  144,  855 ;  angustidens, 
416*,  901*,  917,  926;  megalodon, 
901 

Carcharopsis  Wortheni,  644*,  647 

Carcinosoma  ingens,  557 

Cardinia  concinna,  790 ;  Listeri, 
790 

Cardiocarpus,  435,  622,  674;  bicus- 
pidatus,  673*,  689 ;  bisectus,  678*, 


689  ;  elongatus,  673*,  689 ;  samar- 

aeformis,  673*,  689 
Cardioceras,  794 ;  dubium,  760 
Cardioceras  family,  760 
Cardiola,     621;     retrostriata,     621, 

627 ;  speciosa,  620 
Cardiomorpha  Missouriensis,  690 
Cardiopsis  radiata,  647 
Cardiopteris,    645;    frondosa,   704; 

polymorpha,  704 
Cardita,  916;  planicosta,  926;    sul- 

cata,  926 

Carditatnera  arata,  917 
Cardites  crenatus,  774 
Cardium,  916 ;  Dalli,  917  ;  diversum, 

916;  dumosum,  854;  Eufaulense, 

854 ;  Hatchetigbeense,  915 ;   Hil- 

lanum,  865 ;  Islandicum,  983,  984 ; 

laqueatum,     917;     Purbeckense, 

791 ;    speciosum,   855 ;    Virginia- 

num,  917 

Carentonian,  859,  866 
Caribbean  Sea,  20,  44,  45,  49,  936 
Caricella  Claibornensis,  897*,   916; 

demissa,  916  ;  doliata,  916 ;  Leana, 

915 

Caridoids,  421§ 
Carinaropsis,  482 
Carmel    (Mt.),    Conn.,    801*,    802, 

807 

Carmon,  521 
Carnallite,  120 
Carnic  (Lower),  757 
Carnivores,  902,  903,  910,  911,  918, 

919,  924,  926,  927,  929,  930,  931 
Caroline  Archipelago,  38,  39,  145, 

850 
Carp    River,   unconformability    at, 

465*,  468 
Carpathian  Mts.,  32,  41,  365,   774, 

793,  812,  920 
Carpinus,  896 
Carpolithes  Brandonensis,  896* ; 

irregularis,  895*,  896 
Carrara,  309 
Carrizo  Creek,  Cal.,  892 
Carson  Lake,  811 
Carterella,  432* 
Carya,  550,  896 
Caryocrinus,    550;    ornatus,    547*> 

550,551 

Caryoderma,  919 
Caryophyllia,  860 
Cascade  Range,  25,  28,  29,  80,  40, 

280,  296  (volcanoes),  300,  389,  739, 

747,  811,  830,  831,  945 
Cashaqua  shale,  605 
Caspian   Sea,  22,  83,  49,  199,  200, 

296,  768,  776,  857 
Caspian  steppes,  156 
Cassia,  921 
Cassidaria  dubia,    916;    Petersoni, 

916 
Cassidulus,    84§;    sequoreus,    855; 

florealis,  854 
Cassiope  hypnoides,  945 
Cassowaries,  54 
Castor  Canadensis,  55,  1000 ;  fiber, 

55 

Castoroides  Ohioensis,  1000,  1012 
Casuarina>,  922 
Casuarius,  54 


INDEX. 


104T 


Catacecaumene    region    volcanoes, 

296 

Catarractes  affinis,  1002 
Catchfly,  945 
Catlinite,  468 
Catopterus  gracilis,  751* 
Catopygus  carinatus,  866 ;  pusillus, 

854 
Catskill  beds  (group),  576,  602 

—  Mts.,  25,  188,  225,  357,  605,  636, 
744,  745,  946 

—  shaly  limestone,  559 
Caucasus,  41,  239,  265,  857,  920 
Cauda-galli  epoch,  410 

—  grit,  558,  559,  576,  579,  581,  728 
Caulerpit.es,  688 

Caulinites  sparganioides,  839 
Caulopteris,  584,  699 ;  ad  vena,  584 ; 

antiqua,     583* ;     elliptica,     705 ; 

gigantea,   705;    Lockwoodi,   611, 

622;  microdiscus,  705;  peltigera, 

705 ;  Wortheni,  645 
Cave  animals,  927,  940 
Cavern  formations,  324 
Caverns,  379,  399,  695,  883 ;  making 

of,    116,    130*,    324  (Hawaiian); 

filled  with  vein-material,  328,  334, 

342,  343 ;  nitrates  in,  137 ;  rivers 

in,  207 

Cayambe  Mt.,  26 
Cayuga  Lake,  555,  559,  602,  603,  604, 

605 ;  jointed  rocks,  112* 
Ceanothus,  921 
Cebochaerus,  926 
Celastrinites  laevigatus,  839 
Celastrus,  921 
Celebes,  19,  40,  309 
Celestite,  493,  540 
Cement,  79,  80,  555 
Cementing  coal,  661 
Cenomanian  group,  815,  832,  857, 

858,  859,  860,  865,  866 
Cenozoic  time,  879 
Centipeds,  419 

Central  America,  40,  145,  296  (vol- 
canoes), 297,  338 
Central  Continental  Interior.    See 

Interior  Continental 
Central  Pacific  E.  K.,  26 
Centroceras,  602 
Centronella,  579 
Cephalaspids,  417,  625 
Cephalaspis,    564,   566*,  587,   625; 

Campbelltonensis,     588* ;    Daw- 

soni,    588*,    591;    Lyelli,    624*; 

Murchisoni,    566,    567;     ornata, 

567 

Cephalization,  414,  437-439 
Cephalophora,  424 
Cephalopods,   59,    130,   424§,   425*, 

501,  569 

Ceram  Island,  38 
Ceratiocarids,  550,  721;  Cambrian 

(Upper),    488;    Chemung,    604; 

Hamilton,  599,  600*  ;  Lower  Silu- 
rian, 521;    Niagara   epoch,  549; 

Upper  Silurian,  574 
Ceratiocaris,  482,  521,  546,  557,  565, 

567;    Angelini,   519,    520*,    549; 

Deweyi,  549,  550 ;    papilio,  566*  ; 

pusilla,  546 ;  sinuata,  691 ;  tenui- 

striata,  566* 


Ceratites,  757,  770,  771,  774;  Malm- 
greni,  792;  Middendorfi,  773; 
nodosus,  770,  771*,  774 

Ceratodus,  59,  176,  417,  418,  687, 
725,  772,  774,  797  ;  culmination  in 
Triassic,  869  ;  Capensis,  770 ; 
favosus,  687 ;  Guntheri,  760 

Ceratolichas,  591 

Ceratops,  856 

Ceratops  beds,  828,  845,  847,  849 

Ceratopsidae,  846,  848 

Ceratopsids,  828,  847,  856,  864,  870 

Ceratosaurus  nasicornis,  765,  766* 

Ceraurus  (Cheirurus),  422,  482,  500, 
502,  508,  513,  516,  520,  521,  546, 
568,  625;  bimucronatus,  520, 
565*;  Niagarensis,  550,  551; 
pleurexanthemus,  509*,  515 ; 
Satyrus,  503 ;  Sternbergi,  568 

Cerithiopsis,  916 

Cerithium,  780,  854,  922  ;  Austi- 
nense,  836;  Claibornense,  916; 
concavum,  926 ;  cymatophorum, 
927  ;  elegans,  926 ;  Hillsboroense, 
898*,  916;  mutabile,  926;  pli- 
catum,  926 ;  variabile,  925 

Cernaysian  group,  884,  923,  925 

Cerussite,  335 

Cervalces  Americanus,  999* 

Cervus,  927;  anoceros,  927;  Fal- 
coneri,  927  ;  giganteus,  999, 1005 ; 
Muscatinensis,  966;  Polignacus, 
927 ;  verticornis,  927 

Cestracion,  60,  416*,  643 ;  Philippi, 
416*,  797 

Cestracionts,  416*§,  797,  869  (four 
modern)  ;  Corniferous,  589  ;  Sub- 
carboniferous,  644,  647 ;  Carbo- 
niferous, 680*  ;  Permian,  707 ; 
Triassic,  772;  Cretaceous,  812, 
843*,  863,  869 

Cetaceans,  902,  912*,  925 

Cetiosaurus,  786,  790 ;  brevis,  863  ; 
Oxoniensis,  786 

Cetotherium,  925 ;  cephalus,  912* 

Chabazite,  68 

Chsenohyus,  918 

Chaeropotamus,  924  ;  Cuvieri,  926 

Chaetetes,  505 

Chagos  Islands,  737,  937 

Chain  coral.     See  Halysites 

Chalcedony,  323,  340,  859 

Chalcedony  Park,  135 

Chalcocite,  385,  745 

Chalcopyrite,  70§,  331,  334,  335,  339, 
340,  538,  542 

Chaleur  Bay,  444 

Chalicotherium,  919,  925,  927 

Chalk,  79§,  205  (absorptiveness), 
817 

—  formation,  401,  407,  738 

— ,  Gray,  Lower,  Upper,  White, 
858 

—  period,    738.      See    also    Creta- 
ceous 

—  marl,  865,  866 

Challenger  Expedition,  49,  59,  144, 

230,  241,  718,  823 
Chama,    780,     834 ;      crassa,    917 ; 

squamosa,  926 
Chamaarops  humilis,  58 
Chamops  segnis,  849 


Chamouni,  233,  243,  246 
Champlain  (Lake),  200, 232, 467, 532, 

558,  982* 
Champlain  period,  American,  981 ; 

subsidence,    981  ;    foreign,  995 ; 

elevation  at  close  of,  993 

—  group  of  the  Lower  Silurian  in 
New  York,  489 

Champsosaurus,    902 ;    profundus, 

856 ;  Saponensis,  902 
Chara,  72  (ash  of),  582*,  590  ;  fcetida, 

72 ;  Stantoni,  839 
Charcoal,    62§,    124,   662;  mineral, 

712 
Charleston  earthquake  of  1886,  373, 

374,  375 

Chart.     See  Map 
Chasmops,  521 

Chatham  Islands,  39,  154,  1019 
Chattahoochee  group,  884,  890,  891, 

898*,  916 

—  River,  890,  891 
Chaudiere  River,  591 
Chazy  epoch,  493 
Cheiracanthus,  625 
Cheirurus.    See  Ceraurus 
Chelonians,  772,  787,  836,  849,  863 
Cheltenham  beds,  775 

Chelys  Blakei,  790 
Chemical  attraction  as  a  dynamical 
agency,  117 

—  changes  producing  heat,  258 

—  products,   mechanical   work   of, 
137,  138* 

—  work,    118-140;    solution,    118- 
122 ;   oxidation  and  deoxidation, 
122-128;      hydration,     carbonic 
acid,  humus  acids,  128-135;  sili- 
ca,   135-136 ;    living    organisms, 
136-137 ;  chemical  products,  137- 
139 ;  concretionary  consolidation, 
139-140 

—  of  metamorphism.    See  Meta- 

morphism 

Chemnitzia,  781 ;  gloriosa,  855 
Chernung  period,  602 
Chenopus  liratus,  916 
Cherry  Ridge  group,  606 
Chert,  63§,  82§ 
Chesapeake  Bay,  744,  819,  889,  891 

—  epoch,  884,  891 

Chester  group,  634,  637,  638,  639, 
642,  645,  647,  709 

Chestnut,  435,  837 

Chetetes,  704 

Cheyenne  River,  266 

Chiastolite,  65*,  66§ 

Chico  group  (beds),  815,  818,  830, 
831,  840,  889;  see  also  Shasta- 
Chico  series 

Chile,  137;  snow-line  in,  234;  vol- 
canoes of,  296 ;  earthquake  in, 
349 ;  recent  changes  of  level  in, 
349  ;  Cretaceous  in,  857,  867 

Chilhowee  sandstone,  468 

Chilian  Cordillera,  857 

Chiloe,  23 

Chilopoda,  419 

Chimaera,  510 

Chim«erids,  416§,  574,  725 

Chimaeroids,  Corniferous,  587,  589*; 
Cretaceous,  828 


1048 


INDEX. 


Chiraborazo  (Mt.),  26,  274,  290,  296 

China,  51,  84,  145;  Cambrian  in, 
482  ;  Lower  Silurian,  522  ;  Upper 
Silurian,  564;  Devonian,  628; 
Carboniferous,  632,  693,  696 ;  Cre- 
taceous, 833 

China  Sea,  92T 

Chinate  Mts.,  8T4 

Chipola  epoch  (group),  884,  891, 
899*  917 

Chipola  sands  (fossiliferous),  890, 
891 

Chirolepis,  417,  620;  Canadensis, 
618* ;  Trallii,  417* 

Chiropters,  918 

Chirotherium,  772*,  773,  774 ;  Eei- 
teri,  692 

Chirox,  917 

•Chiton,  424§ ;  Canadensis,  514 ;  car- 
bonarius,  690 

Chlamydotherium,  1004 

•Chlorine,  63 

Chlorite,  68§,  89 

—  argillyte,  89§ 

—  rocks,  79§,  83,  84,  86,  87,  819, 449 

—  schist,  89§ 
Chloritic  marl,  865 
Chlorophyll,  136 
Cholaster  peculiaris,  646 
Cholodus,  692 
Chomatodus,  692 
Chondrites  Colletti,  688 
Chondrodite,  63,  67§,  79,  319,  447, 

449,  450,  531 
Chondroditic    limestone,  79§,  449, 

450,531 
Chonetes,  546*,  550,  552,  562,  579, 

611,  621,  622,  642,  674,  700 ;  cor- 
nutus,  546*,   550 ;  Dalmanianus, 
703;  deflectus,  592;  Flemingi,  685; 
Hardrensis,  625,  628 ;  hemisphae- 
ricus,  590,  592 ;  Illinoisensis,  642*, 
647;    latus,   427*     567;    lepidus, 

612,  620 ;    lineatus,  590 ;    meso- 
lobus,    675*,    690 ;    mucronatus, 
592,  602;  Novascoticus,  562;  or- 
natus,  642*,  646  ;    planumbonus, 
646  ;  scitulus,  612,  620 ;  setigerus, 
598*,   601,  620;    striatellus,  567, 
568 

lophyllum    Niagarense,    547*, 

0 

Choristoceras,  771  ;  Haueri,  774 
Chouteau  limestone,  637,  646 
€hrestotes  Danae,  691 ;  lapidea,  691 
Christian ia,  309 
Christianite,  186 
Christmas  Island,  151  (height) 
•Chrome-spinel,  88 
Chrysalidina  gradata,  432*,  860* 
Chrysoberyl,  449 
Chrysoeolla,  335 
Chrysodomus  Stonei,  917 
Chrysolite,  67§ 

Chrysolitie  gabbro,  272;  hornblen- 
dyte,  5:32 ;  pyroxenyte,  582 

—  rocks,  88-89 
Chrysomelids,  771 
Cicada,  419 

Cidaris,  59,  641,  760,  779,  834,  840 ; 
Blumenbachii,  778*,  791;  clavi- 
gera,  8664  erfitosa,  866;  flori- 


gemma,  790,  791 ;  splendens,  854 ; 

Texana,  837 ;  vesiculosa,  866 
Cimolestes  incisus,  853* 
Cimoliosaurus,  845 
Cimolos  Island,  296  (volcanoes) 
Cincinnati,  Ohio,  533 

—  anticline.     See  Cincinnati  uplift 

—  beds,  492,  504,  506,  511,  514,  515, 
516  ;  characteristic  species,  516 

—  epoch,  494,  559 

—  group,  489 

—  Island.    See  Cincinnati  uplift 

—  uplift,   387§,  490,  494,  522,   527, 
532-533,  537,    539,   540,   633;  in- 
fluence of,  in  the  Upper  Silurian, 
571 

Cinders,  volcanic.     See  Volcanic 
Cinnabar,  335 
Cinnabar,  Mt.,  829 
Cinnamomum,  837,  896,  921 ;  ellipti- 

cum,  839  ;  Mississippiense,  895*, 

896 ;  Scheuchzeri,  839 
Cinnamon,  921 
Cinulia,  861;  avellana,   861*;  pul- 

chella,  854 
Cirripeds,  420*,  421§,  518  (earliest), 

579,  720 

Cladiscites  tornatus,  771* 
Cladodus,    692,  702;    Clarki,  619*, 

620;   Fyleri,  619*,  620;  Kepleri, 

620 ;  marginatus,  702  ;  sinuatus, 

019*;  spinosus,  644*,  647 
Cladonia,  75;  rangiferina,  75 
Cladopora  labiosa,  592 
Cladoxylon  mirabile,  621 
Claiborne  epoch  (group),  884,  885, 

889,  891,  916 

—  (Lower),  884,  885,  888,  890,  896, 
897*,  915,  916 

—  (Upper),  896,  897* 
Clam,  423,  424§ 

Claosaurus,    847,    856;    annectens, 

844*  845*,  847 

Clarion  coal,  652  ;  sandstone,  652 
Clastic  rocks,  75§ 
Clathropora  flabellata,  514 
Clathropteris,  740,  750  ;  rectiuscula, 

749* 

Clava  Chipolana,  917 
Clavilithes  h'umerosus,  916  ;  Missis- 

sippiensis,  916  ;  pachyleurus,  916; 

Penrosei,  916 

Clay,  76§,  80§,  81  (kinds),  134 
Clay-ironstone,  70§,  82 
Clay  marls,  815,  821,  854 
Clay  shale,  638,  748,  892 ;  slate,  80§, 

84 
Clayey  layers,  plication  of,  208, 209* 

—  rocks,  12,  313 
Clayton  beds,  888 
Clayton  Peak,  360*,  361 

Clear  Creek  limestone,  543,  559 

Clear-Fork  beds,  660 

Clear  Lake.    See  Borax  Lake 

Cleavage  in  rocks,  92,  112*,  113*  370 

Cleodora,  425* 

Clepsydrops,  687 

Clepsysaurus  Pennsylvanicus,  753, 
754* 

Cleveland  shale,  606,  619,  620 

Clidastes,  826  ;  iguanavus,  848 ;  pro- 
python,  848 ;  velox,  848* 


CMophorus  Pallasi,  707 

Cliffs,  wearing  of,  220,  221* 

Climacograptus,  514,  520  ;  bicornis, 
510*;  Emmonsi,  470*;  typicalis, 
516 

Climactichnites  Fosteri,  479*  ;  Wil- 
soni,  479* ;  Youngi,  479* 

Climatal  changes,  causes  of,  253-257 

Climatal  development,  1026 

Climate,  effects  on  the  work  of 
rivers,  189 

— ,  Cambrian,  484;  Carbonic,  711- 
712 ;  Champlain,  940 ;  Cretaceous, 
872-873,  877 ;  Eocene,  929  ;  Gla- 
cial, 940, 943, 944 ;  Lower  Silurian, 
524;  post-Mesozoic,  875,  877; 
Paleozoic,  727 ;  post- Paleozoic, 
736 ;  Permian,  737 ;  Quaternary, 
940 ;  Tertiary,  921,  939  ;  Triassie 
and  Jurassic,  791, 792-793  ;  Upper 
Silurian,  574 

Clinch  Mountain  sandstone,  538 

Clinkstone,  85§ 

Clinometer,  100*f  ;  use  of,  for  meas- 
uring distant  slopes,  28 

Clinton  beds  or  epoch,  356, 410, 535r 
540,  544,  549-550,  552T  563,  570, 
572,  577 

—  and  Medina,  British  equiva- 
lent of,  563 

Cliona  sulphurea,  158 

Clitambonites,  500 ;  AmericanusT515 

Clupea,  862 

Clymenia,  614  (first  American),  620r 
626;  laevigata,  627;  Neapolitanat 
614* ;  Sedgwicki,  626*  ;  undulata, 
627 

Clymenia  limestone,  627 

Clypeus  Hugi,  428* 

Coahuila  Valley,  200 

Coal,  62§,  124,  136,  143,  154,  485, 
727,  775  (jet)  ;  analyses,  661,  662, 
663,  713 ;  formation  of,  from  vege* 
table  debris,  712-714  ;  impurities, 
663,  664 ;  kinds,  661 ;  origin,  71, 
155,  653,  654,  655;  plant-remains 
in,  653-655,  658,  663,  664;  struc- 
ture, 709,  710 ;  vegetable  material 
of:  kinds  and  composition,  712, 
713 

—  in  Calciferous,  493;  Carbonifer- 
ous  and    Subcarboniferous,   634, 
636,   639,  648,  661-664,  674,  693, 
694*,  695,  696  ;  Permian,  660,  684, 
685,  698;  Triassie,  742,  744,  745, 
748,  755,  769  ;  Jurassic,  775,  776 ; 
Cretaceous,  818,   820,    822,    825, 
826,  827,  828,  829,  831,  857,  865, 
872 ;  Tertiary,  887,  892,  920,  922, 
927 

—  areas  of  N.  America,  635,  825 

—  fields  of  Europe,  693,  694,  696 
Coal-beds,  bowlders  in,   664,   709; 

burning  of,  84,  266,  313  (changed 
to  coke) ;  inetamorphic  changes 
in,  315,  453;  thickness  of,  651, 
652,  653,  656,  657,  658 
Coal-measures,  dirt-beds  of,  653, 
658 ;  false,  639 

—  section  of,  near  Nesquehoning, 
Pa.,  649* ;  at  Trevorton  Gap,  Pa., 
650* 


INDEX. 


1049 


Coal  period,  631,  647 

Coalville  (Utah)  coal-bed,  825,  829 

—  group,  825,  829 
Coast  barriers,  224*,  225* 

—  belt.    See  Coast  Chain 

—  cordillera,  25 

—  Chain,  390,  739,  818,  937 

—  Range,  Cal.  and  Oregon,  30,  659, 
739,  809,  810,  811,  830,  885,  892 

—  of  British  Columbia,  389,  739, 
812 

Coastal  plains,  24§ 

Coasts,  water-line  of,  346 

Cobalt,  70,  342,  344 ;  oxide,  844 

Coblenzian  beds,  626 ;  fauna,  570 

Cobscook  Bay,  552 

Coccolepis,  699 

Coccoliths,  72,  140,  437§,  S38§,  859 

Cocconeis  atmospherica,  163,  164*  ; 
lineata,  163,  164* 

Cocconema  cymbiforme,  163,  164* 

Coccospheres,  72 

Coccosteid,  616* 

-Coccosteus,  566,  619,  625,  626,  627  ; 
decipiens,  624*  ;  macromus,  621 ; 
occidentals,  588* 

•Coccosteus  family,  618 

•Cochliodonts,  643§,  647,  705 

-Cochliodus  contortus,  644*,  702*; 
nobilis,  644*,  647 

€ochlocents,  771 

•Cockroaches,  156,  419,  574,  677,  721, 
723;  Carboniferous,  677,  679,  691, 
701,  722 ;  Paleozoic,  721,  722 ;  Per- 
mian, 686  ;  Triassic,  757,  771 

Codaster,  516,  601 

•Ccelacanthus,  679,  680,  692,  705  ;  ele- 
gans,  680*,  692 ;  granulatus,  707 

•Coelenterates,  41 8§,  419,  430§ 

•Coelodus,  836 

Coelospira,  579 ;  hemisphaerica,  550  ; 
Scotica,  567,  569 

Coelurus  gracilis,  836 

Ccenenchyma,  431§ 

Coenograptus  graeilis,  510*,  515,  516 

•Ccenograptus  zone  of  Lapworth,  515 

Coffee  sands,  824 

•Coke,  313,  661,  663,  713 

'Coleolus,  599 ;  acicula,  612,  620 

•Coleopters,  54,  419,  794,  900  (num- 
ber at  Florissant) ;  Coal-measure, 
679,  691,  702;  Triassie,  771;  Gla- 
cial, 946 

•Colodon,  918 

•Colombia,  Cretaceous  in,  867 

Colonoceras,  918 

•Color  of  rocks,  400 

Colorado,  23  (height),  26,  85,  87, 109, 
160,  188,  189,  203,  207,  250,  265, 
266,  296,  313,  338,  340,  343,  363, 
364,  447 ;  silver  mines,  340 ;  ter- 
races, 363*  ;  trachyte,  275* ;  see 
also  Front  Range  of  Colorado 

— ,  Archaean  in,  444,  449  ;  Cambrian, 
464,  476;  Trenton,  495,  509,  515; 
Devonian,  580 ;  Subcarboniferous, 
469,  639  ;  Carboniferous,  469,  475, 
658  ;  Permian,  693  ;  Triassic,  187, 
203,  363,  721,  746,  747,  756  ;  Juras- 
sic, 187,  363,  747,  748,  758,  760, 
761,  762,  763-;  Cretaceous,  187, 
574,  363,  82C  ,(coal),  828,  880, 


847,  848 ;  Tertiary,  185,  882,  886, 
893,  901,  909,  935  (elevation)  ; 
post-Mesozoic,  876 

—  Canon  (Grand  Caflon),  107,  186, 
187*,  188*,  189,  362,  381,  447,  464, 
469,  484,  541,  658,  660,  747 

—  Chain,  389 

—  desert,  160 

—  epoch,  815,  821,  823,  824, 825, 826, 
829,  830,  831,  855,  873 

—  plateaus,  109,  110*,  362,  363* 

—  Range.    See  Front  Range 

—  River,  25,  26,  30,  200,  362 
Coloreodon,  918 
Colossochelys  Atlas,  923,  927 
Colubridse,  923 

Columbia  River,  25, 30,  226, 831,  885, 

895 

Columbian  formation,  974 
Columbus  limestone,  581 
Columnar  structure,  261*,  262* 
Columnaria,    501,    515;    alveolata, 

504,  505*,  513,  517  ;  calicina,  513 ; 

Halli,  513;  incerta,  503;   parva, 

503 
Comanche  group  (beds),  815,  817, 

834,  874* 

—  Peak  chalk,  817,  819,  836 
Comarocystites     punctatus,     514 ; 

Shumardi,  514 
Comatulae,  402,  429§ 
Comatulids,  429,  779 
Comb  (mining  term),  333§,  722 
Comoro  Islands,  296  (volcanoes) 
Compact  rocks,  80§ 
Compass,  clinometer,  100*§ 
Cotnpsacanthus,  692  ;  laevis,  692 
Compsaster  formosus,  646 
Compsemys,   850,  856;  plicatulus, 

767 

Compsognathus  longipes,  786 
Comptonia,  921 
Com  stock  lode,  339 
Concentric  discoloration,  139,  140* 

—  structure,  96*§,  97*,  98, 127, 140*, 
289,  327 

Concepcion,  earthquake  at,  213,  349 

Conchifers.     See  Lamellibranchs 

Concretionary  consolidation,  139- 
140* ;  rocks,  79,  80,  82,  96,  139, 
344,  690  ;  structure,  132,  289,  327 

Concretions,  87,  96*,  97*,  139,  152, 
195,  230,  274,  307,  327,  493,  603, 
605,  606,  657,  665,  677,  688,  775, 
822,  825,  847,  888 

Condros,  sandstones  of,  626 

Conduit  of  a  volcano.  See  Vol- 
cano 

Conewango  basin,  945 

Coney  Island,  224 

Conferva?,  60,  72,  133,  140,  157,  437, 
582,  583* 

Conformability,  114§,  115*,  391,  400, 
404,  406,  807,  809 

Conglomerate,  80§,  292  (volcanic), 
400  (coral) 

— ,  limestone,  78§ 

Congo  River,  30 

Congress  Springs,  analysis  of 
waters,  121 

Conifers,  53 ;  ash  of,  75 ;  time 
range,  409* 


Coniophis  precedens,  848 

Coniston  grits,  563  ;  limestone,  518, 
519,  520 

Connecticut,  mean  height,  23  ; 
Branchville  Mine,  321  ;  Thimble 
Islands,  949  ;  copper  ores,  745 ; 
iron  ore  beds,  127 ;  marble,  524, 
530,  531  ;  Triassic,  111,  740,  741, 
742,  751,  753,  754,  755,  799,  800, 
801*  (map),  808 

—  River,  87,  172,  212  (tide)  ;  sound- 
ings at  mouth  of,  226* 

Range,  358 

Connecticut  River  valley  drift,  956 

—  valley,  194*  (terraces),  195,  443  ; 
Devonian,  310,  531 ;  Lower  Hel- 
derberg,  558 ;  Niagara,  541 ;  Tri- 
assic, 264,  316,  740 

—  trough,  461,  536,  537,  541,  633, 

715,  743 

Connellsville  sandstone,  651 
Connoquenessing  sandstones,  656 
Conocardium,  520,  562,  621 ;  aequi- 

costatum,  567 ;  cuneus,  585*,  590  ; 

dipterum,    519* ;      immaturum, 

514 ;  Meekanum,  647 
Conocephalites,  482,  483 
Conocoryphe,  481,  482  ;  minuta, 

479* 

Conodonts,  621 
Conomitra  Hammakeri,  916 
Conophyllum  magnificum,  590 
Conorbis  alatoideus,  916 
Consolidation   (see    also  Solidifica- 
tion), 289;  by  calcareous  waters, 

133,  139 ;  by  ferruginous  waters, 

134,  139 ;  by  iron  oxide,  128 ;  by 
metamorphism,  316,  322;  by  sili- 
ceous solutions,  135,  139, 313,  823, 
800 

— ,  concretionary,  139-140* 

—  of  coral  reefs,  151 

Constance,  Lake,  921 

Contact-minerals  and  contact-phe- 
nomena, 312§,  313,  314,  333,  810  ; 
veins,  334 

Continent,  definition  of,  34§,  35 

—  making,  376§ 
Continental  border,  743,  744 

—  Interior.    See  Interior  Continen- 
tal 

—  plateaus,  379 

Continents,  383 ;  arrangement  of, 
17,  21 ;  as  individuals,  22  ;  heights 
of,  23,  380 ;  mostly  in  the  northern 
hemisphere,  394 

— ,  mountain  chains  and  volcanoes 
mostly  on  the  borders  of,  392 

— ,  northern  and  southern,  in  a 
zigzag  arrangement,  394 

— ,  origin  of,  383 ;  submerged  bor- 
ders, 17  ;  system  in  reliefs,  30-35 

Continguiban  group,  867 

Contraction,  effects  of,  260,  327, 
381 ;  in  glass  and  rock,  264,  265 ; 
in  volcanic  work,  283  ;  on  drying 
and  on  cooling  makes  fissures, 
32T 

—  theory  of  mountain-making,  883- 
386 

—  and    expansion,    259-265,    261*, 


1050 


INDEX. 


Conularia,  481, 488, 506,  514,  549,  562, 
567,  574,  578,  579,  613,  698,  705, 
707,  719  (time  range) ;  elegantula, 
590;  formosa,  516;  Homfrayi, 
520 ;  lata,  578  ;  longa,  551 ;  Niaga- 
rensis,  551 ;  Trentonensis,  507*, 
514,  516 

Conulites  flexuosus,  562 

Conulus  chersina,  966 

Conus,  916,  922;  deperditus,  926; 
Okhotensis,  927 

Cook's  Inlet,  760 

Cooling,  contraction  from,  in  case 
of  fusion,  261*,  263,  264,  883 

—  of  the    globe,    376 ;    its   conse- 
quences, 383,  939 

Cooper  beds,  888 

Coosa  coal-fields,  657 ;  series,  468 

Copepods,  421§ 

Copiapo  earthquake,  349 

Copodus,  643 

Copper,  70,  333;  chloride,  294; 
native,  in  drift,  953 ;  oxide,  344 ; 
pyrites  (see  Chalcopyrite) ;  see 
also  Superior  (Lake)  region,  cop- 
per 

Copperas,  123,  125 

Coprolites,  73§  (analyses);  Upper 
Silurian,  567;  Triassic,  754;  Ju- 
rassic, 785,  786* 

Coral,  precious,  72,  431;  Coral 
atolls  (see  Atolls) 

—  bed,  Taylorville,  Cal.,  759 

—  beds  of  the  Siliceous  group  of 
Tennessee,  688 

—  formations,  144-152 

—  island,  water  supply  of,  206 
subsidence,  936-937 

—  islands,  20,   120,   131,  144§,  145- 
148,  145*,  146*,  161,  221,  225,  295, 
350,  392,  937  ;  most  numerous  in 
the  tropical  Pacific,  145  ;  number 
in  the  several  groups,  145;  sec- 
tions of,  149*,  284*,  285* 

—  oolyte,  147 

—  polyps.     See  Polyps 

—  rag,  411,  775,  790 

—  reef  period,   in    the    Devonian, 
584 

--reefs,  144§,  148-152 

Corallian  group,  760,  775,  777,  780, 

790 
Coralline  limestone  of  the  Niagara, 

540,  543,  549 
Corallines,  56,  72,  437§ 
Coralliochama  Orcutti,  841* 
Coralliophila  magna,  916 
Corallium  nobile,  72 
Corals,  55,   140,  427*,  429*;  limits 

of  growth,  144,  145,  146,  149* 
Corax,  843  ;  heterodon,  843* 
Corbicula,   828,  829 ;  annosa,   837  ; 

cytheriformis,  856;  densata,  917; 

emacerata,  837  ;  occidentals,  856 
Corbis  distans,  916 
Corbula,    756,   780,   828,  916,  917; 

Aldrichi,   915 ;    Forbesiana,  791  ;• 

idonea,  917 ;  inflexa,  791 ;  longi- 

rostris,  925  ;  Neocomiensis,  867  ; 

oniscus  var.   fossata,  916;  pecti- 

nata,  791 ;  pisum,  926 
Cordaianthus,  673* 


Cordaicarpus  Gutbieri.  673*,  689 

Cordaites,  435,  611,  612,  639,  667, 
672,  673*,  674,  689,  699,  704  ;  bo- 
rassifolius,  646,  689 ;  Clarki,  610, 
621 ;  costatus,  672*,  689  ;  diversi- 
folius,  689;  Gutbieri,  673*  ;  Mans- 
fieldi,  672 ;  Robbii,  595*,  596,  601, 
622 

Cordaites  shales,  693,  594 

Cordillera,  25§,  3S9,  390§ 

—  of  the  Rocky  Mts.,  390 
Cordillera  glacial  area,  956 
Cordylocrinus,  562 
Corea,  40 

Cork,  composition  of,  713 
Cormorant,  852,  902 
Cornbrash,  775,  790 
Corneo-siliceous  sponges,  431§ 
Corneous  sponges,  431§ 
Corniferous  limestone,  576,  579 
Corniferous  period,  579 
Corniornis,  852 
Cornulites  serpularius,  567 
Cornus  suborbifera,  839 
Cornwall,    317,    936    (united    with 
Brittany) 

—  veins,  329*,  332*,  333* 
Cornwallis  I  si.,  495 
Coroniceras  Bucklandi,  781*,  790 
Coronocrinus,  562 
Coronura,  591 

Corrasion,  168§,  941 

Correlation  of  geological  records, 
398-404  (difficulties,  398 ;  means, 
399;  precautions  in  the  use  of 
fossils,  402) ;  difficult  in  crystal- 
line terranes,  458 

—  of  Archaean  subdivisions,  457 
Corrosion,  126,  136,  338-342  . 
Corsica,  87 

Corsyte,  87§ 
Cortez  Range,  366 
Corundum,  64§,  79,  320,  455 
Corycephalus,  591 
Corydalis  Brongniarti,  704 
Coryphodon,  903,  907,  917,  918,  923, 

925,  929  ;  hainatus,  903,  904* 
Coryphodon  beds,  886 
Coryphodonts,  928 
Coscinodiscus,   163,   164* ;  apicula- 

tus,   894* ;    atmosphericus,    168, 

164* ;  gigas,  894* 
Coseguina  volcano,  163 
Cosmoceras  Jason,   781* ;   Parkin- 

soni,  790 

Cosoryx,  911,  919 
Costa  Rica,  891  (Miocene) 
Coteau    des    Prairies,    942    (drift), 

945 

Cotopaxi  (Mt.),  26,  274,  296 
Cottonwood  Canon,  469,  476,  581 

—  Creek,  895 
Country  Peak,  783 

—  rock,  331§ 
Coutchiching,  446 

Crabs,  146,  420*,  488,  707,  717,  720, 

782 
Crag,    Pliocene    of    England,    921, 

927 

Craie  glauconieuse,  866 
Cranberry  mine,  450 
Cranes,  923 


Crania,  59,  425§,  516,  520,  719 ;  an- 

tiqua,  427*  ;  divaricata,  519*,  520  ; 

scabiosa,  514,  516 
Crassatella,    916;    alaeformis,    915; 

alta,  897*,  916  ;  antestriata,  915  ; 

curta,  854;  flexura,  916;  lineata, 

855;   littoralis,  854;  melina,  917; 

Marylandica,  917  ;  Mississippien- 

sis,    916;     sulcata,   926;    texalta, 

916;    Texana,  916;    Trapaquara. 

916;    tumidula,    915;    undulata, 

917 ;  vadosa,  854 
Craters,  267§,  269*,  270*,  284*,  28G*  ;. 

see  also  Volcanoes 
Craw-fish,  158,  771 
Crazy  Mts.,  876 

Crenitic  hypothesis  of  Hunt,  321 
Creodonts,  903,  906,  907,  917,  918, 

923,  924,  925 
Crepicephalus,  503 
Crepidula,  642 ;  costata,  900* ;  forni- 

cata,  994 

Cretaceous  period,  812;  N.  Ameri- 
can, 812  ;  foreign,  856 
—  in  N.  America,  map  of,  812,  813*v 

814 

— ,  Lower,  816 
— ,  Upper,  837 

Cretacic  period.     See  Cretaceous 
Cricoceras  Dtivalii,  862* 
Cricodus,  417* 
Cricotus  Gibsoni,  687  ;  heteroclitus, 

687* 

Crillon  (Mt.),  238 
Crinidea  (Crinideans),  429 
Crinoidal  limestones,  404,  594,  636,. 

652 
Crinoids,  60,  72,  138,  140,  142,  310, 

314,   402,  428*,   429*§,   430§,  486, 

532*,  541 

Criocardium  dumosum,  854 
Cristellaria  cultrata,  791 
Crocodiles,  54,  415;  Jurassic,  768; 

Tertiary,  901,  902,  923,  927 
Crocodilians,  Cretaceous,  848,  863, 

870,  871  ;  Jurassic,  760,  787  ;  Tri- 
assic, 751,  754*,  758,  772,  773 
Crocodilus  Elliotti,  901 ;  Hastings!*,. 

926;  Squankensis,  901 
Cromer  forest  bed,  927 
Crooked  River,  749 
Cross-bedded    structure,  92§,  93*, 

194,  603,  658,  742,  825,  827,  888 
Cross  Sound,  288 
Cross-Timber  (Lower)  sands,   815, 

824,  854 

Crossopterygians,  417§,  619,  725 
Crotalocrinus    rugosus,   564*,    565r 

567 

Croton  River  water  analyzed,  121 
Crushing,  259,  322,  326,  338,  452 
Crustaceans,  420*,  421§,  422,  423§, 

437,    438;     derivation,    720-721; 

tracks,  95,  742 

Crustal  movements,  345,  800 
Cruziana,  474 ;  bilobata,  545*,  546 ; 

similis,  477*,  478 
Cryoconite,  241  § 
Cryolite,  449 

Cryphseus,  591 ;  Boothi,  614 
Cryptacanthia  compacta,  690 
Cryptoceras  capax,  691 


INDEX. 


1051 


Cryptodon  angulatus,  925 

Cryptogams,  53}  136,  140,  434,  435- 
437,  519,  595,  668  (vascular),  672, 
718;  Corniferous,  583*;  Carbo- 
niferous, 666,  727  (culmination)  ; 
Neopaleozoic,  460  (culmination) 

Cryptonella,  579  ;  eudora,  620  ;  lens, 
585* 

Cryptozoon  proliferum,  500 

Crystal  kingdom,  9§ 

Crystallization,  76§,  408  ;  alongside 
of  dikes,  312,  313;  see  also  Meta- 
morphism 

Crystallophyllian,  440  (Archaean 
synonymy) 

Crystals,  figures  of,  explained,  63 

Ctenacanthus,  644 ;  Bohemicus, 
567 ;  latispinosus,  591 ;  major, 
702,  703*  ;  Wrighti,  601 

Ctenacodon,  768  ;  potens,  767* ; 
serratus,  767* 

Ctenodonta,  481,  520,  521 

Ctenodus,  687,  702  ;  Nelsoni,  617* 

Ctenoids,  417*,  836 

Ctenoptychius,  692,  702 

Cuba,  19,  347,  872,  936 

Cubical  coal,  661 

Cuboides  shale,  627 ;  zone,  593,  594 

Cuchara  basin,  893 

Cucullaea  capax,  854 ;  gigantea,  915 ; 
Haguei,  760;  macrodonta,  915; 
oblonga,  791 

Cumberland  Measures,  648 

—  Table-land,  25,  356*,  357,  362, 38C, 
648 

—  (Va.)  Triassic  area,  741 

—  valley,  357 
Cumbrian  Mts.,  463 
Cuneolina  pavonia,  432*,  860* 
Cup-corals.     See  Cyathophylloids 
Cupressinoxylon,  921 
Cupressites,  777 

Cuprite,  385 

Curagoa,  891  (Miocene) 

Curculio  family,  771 

Curculionites  prodromus,  771 

Current-bedding,  93§ 

Cutch,  299,  791 

Cuttle-fishes,  424§,  525,  869  (time 
range) ;  bone,  424 

Cuyahoga  River,  942 

Cyanite,  65§,  66,  83,  318,  319,  449 

Cyanitic  rocks,  83 

Cyathaspis,  625 

Cyathaxonia,  718  /  ! 

Cyathea  compta,  669*,  689 

Cyathocrinus,  597,  646,  690,  707 

Cyathophycus  reticulatus,  515 ; 
subsphaericus,  515 

Cyathophylloids,  431§,  718  (living) 

Cyathophyllum  limestone,  704 

Cybele,  521 

Cycadeoidea  Abequidensis,  755 ; 
Jenneyana,  832 ;  Marylandica, 
831 ;  munita,  832 

Cycads,  53,  409*,  434*§,  435,  718, 
831,  868;  Devonian,  409;  Ham- 
ilton, 596 ;  Carboniferous,  666, 
667,  672*,  682  ;  Permian,  685, 
698,  704  ;  Triassic,  749*,  750,  756*, 
770*,  868  ;  Jurassic,  776,  777,  819, 
868;  Mesozoic,  738,  879;  Creta- 


ceous, 794,  815,  818,  868,  869,  873, 

877 

Cycas  circinalis,  434*,  750 
Cyclocardia  borealis,  984 
Cycloceras,  675  ;  anellum,  514 
Cycloids,  417* 
Cyclonema,  520,    521,    613  ;    bilix, 

514,  516 ;  cancellatum,  546*,  550 ; 

Cincinnatiense,  516  ;  corallii,  567  ; 

quadristriatum,  567 
Cyclophthalmus  senior,  701*,  703 
Cyclopidius  beds,  886 
Cyclops,  421,  423§ 
Cyclopteris,    698  ;     Acadica,    645  ; 

Browni,  622  ;  Hibernica,  626 
Cyclora  parvula,  516 
Cyclospira  bisulcata,  507*,  514 
Cyclostigma,  699  ;  aftine,  610 ;  minu- 

tum,  626 ;  Kiltorkense,  626,  704 
Cyclostomes,  418§ 
Cyclothone,  60 

Cyclus,  720  ;  Americanus,  676,  691 
Cymatolite,  321 
Cymbella     maculata,     163,     164*; 

Scotica,  699 
Cymoglossa,  685 
Cynodesmus,  918 
Cynodictis,  926 
Cynodon,  911,  918 ;  Parisiensis,  924, 

926 

Cynodontomys,  918 
Cyphaspis,  513,  516,  521,  562,  568, 

579,   586,    591,   599;    laevis,   614; 

megalops,  565*,  567 
Cypraea,  916, 922  ;  Carolinensis,  900* 
Cypress,  770*,  939 
Cypricardella  bellistriata,  598* 
Cypricar,dia,  525,  621 
Cypricardinia,  562 
Cypricardites    Montrealensis,    503; 

Niota,     514 ;     rectirostris,     514 ; 

Sterlingensis,  516 
Cypridina  serrato-striata,  627* 
Cypridina  shale,  627* 
Cyprimeria  depressa,  854 
Cyprina  Brongniarti,  791  ;  Morrisii, 

925 

Cypris,  420*,  421 
Cyrena,   855 ;   arenarea,   855 ;  con- 

vexa,     926;     cuneiformis,     925; 

pulchra,    926 ;    semistriata,    926 ; 

tellinella,  925 
Cyrtia  exporrecta,  567 
Cyrtina,    562,    579,    591;    rostrata, 

579,  591 ;   triquetra,  602 ;   umbo- 

nata,  602 
Cyrtoceras,  482,  488,  520,  521,  551, 

561,  562,  568,  586,  591,  599,  625, 

627  ;    dorsatum,    685  ;    ornatum, 

516;    subannulatum,    506,    508*, 
•  514;    subrectum,    558;    Vassari- 

num,  499,  500* 
Cyrtolites,  506,  516 ;  carinatus,  516 ; 

compressus,  507*,  514;  imbrica- 

tus,  516;  ornatus,  516;  Trento- 

nensis,  507*,  514 
Cystideans.     See  Cystoids 
Cystiphyllum,  552,  597,  640 ;  Ameri- 

canum,  590,  601 ;  conifollis,  601 ; 

Siluriense,  564*,  567 ;  varians,  601 
Cystoids,  140,  429*,  430§,  570 ;  Cam- 
brian, 470,  474,  477,  482,  486,  719 


(first)  ;  Calciferous,  499 ;  Chazy, 

501,    503;  Trenton,    505*,     514; 

Utica    and    Hudson,    511,    516; 

Lower  Helderberg,  559*,  560,  561 ; 

Devonian,    577,    719;    Paleozoic, 

719 

Cythara  terminula,  917 
Cythere  Americana,  420*,  691 
Cytherea  aequorea,  916;  imitabilis, 

916;  Marylandica,  917;  Mortoni, 

916  ;    ovata,  915 ;    sobrina,   916  ; 

staminea,  917 
Cytheropsis,  516 

Dachstein  beds,  769,  774 

Dactyloporus  archaeus,  688 

Dacyte,  86§,  272,  273,  296,  304, 
937 

Dadoxylon,  596,  612,  704;  antiquum, 
646 ;  Clarki,  610,  621 ;  Edwardi- 
anum,  755  ;  Ouangondianum,  622 

Dadoxylon  sandstone,  594 

Daemonelix,  914,  915* 

Dakota,  Archaean  in,  444  ;  Cam- 
brian, 466 ;  Cretaceous,  818,  826, 
827,  837,  838,  846,  848,  852  ;  Ju- 
rassic, 760  ;  Niagara,  543  ;  Ter- 
tiary, 886,  902,  919  ;  Triassic,  746. 
See  also  North  D. ;  South  D. 

Dakota  epoch  or  group,  758,  818, 
821,  823,  824,  825,  829,  830,  833, 
887,  839,  840,  855,  872 

Dalmanites,  310,  422,  503,  513,  521, 
546,  551,  561,  570,  578,  579,  586, 
591,  599,  627  ;  aspectans,  587*, 
591 ;  Boothi,  587*,  591,  599,  614 ; 
breviceps,  516  ;  callicephalus,  515  ; 
calliteles,  599*  ;  dentatus,  578  ; 
Hausmanni,  421*,  422,  568,  570; 
limulucus,  549*,  551  ;  nasutus, 
561  ;  phacoptyx,  579  ;  pleuro- 
pteryx,  561,  562,  591;  regalis, 
587*,  591 ;  selenurus,  587*,  591 ; 
tridens,  561 

Dalradian  group,  456 

Damourite,  65§,  84 ;  slate,  84 

Damuda  series,  698,  699 

Dan  River  Triassic,  741,  743 

Dana  Bay,  606 

Dana  Mt.,  glaciers  on,  240,  945 

Danaeopsis,  774 

Danburite,  63,  449 

Danian  epoch,  815,  858,  859,  866 

Danube,  176;  loess  of,  195;  sedi- 
ment in,  190 ;  denudation,  191 

Daonella,  756;  Lommeli,  757,  758, 
774 ;  tenuistriata,  757 

Dapedius,  784* 

Daphaenus,  918 

Daphnia,  421 

Daptinus,  863 

Darien,  Isttimus  of,  22,  41,  256 

Darlington  ca^nel  coal,  676 

Dasyceps  Bucklandi,  706 

Datolite,  63 

Dauphine,  176,  927 

Davallia  tenuifolia,  840 

Davidson  Glacier,  240 

Davis  Strait.  40 

Dawsonella  Meeki,  676*,  690 

Dayia  navicula,  568 

Dead  Sea,  23,  49,  199,  256 


1052 


INDEX. 


Death  Gulch,  128 

Death  Valley,  23,  128,  200 

Debris-cones,  269*,  271§,  285 

Decapods,  420§,  423§,  424,  438§, 
439,  525,  615,  676,  691,  707, 
720 

Deccan,  igneous  outflows  of,  299, 
876,  938 

Deception  Island,  296 

Decomposition,  258,  497,  522,  655, 
665,  710,  822 

Deep  River,  or  Deep  Creek,  Mon- 
tana, 895 

—  beds,  886,  894,  911,  919 

Deep  River  (N.  C.)  Triassic  area, 
741,  743,  799 

Deer,  54,  910,  911,  924,  927,  930 

Deflation,  159§ 

Deformation  of  fossils.     See  Fossils 

Degeneration,  717  ;  in  Insects,  721 ; 
in  Reptiles,  797,  870;  in  Am- 
phibians, 869  ;  in  Birds,  871 ;  in 
Mammals,  931,  1017 

Deistersandstein,  865 

Delaware,  23  (height),  87,  856; 
Cretaceous  in,  816,  823 

—  Bay,  230,  378,  744,  819 

—  flags,  606  ;  limestone,  581 

—  River,  594,  744,  816,  945 

—  Water  Gap,  232,  578 
Delocrinus,  690 
Delphinapterus       catodon,       983  ; 

leucas,  983, 1001* 
Delphinus,  144,  927 
Delta  formations,  98,  191,  195,  196- 

198,  197*,  892 
Delta  Survey,  190 
Deltatherium,  917 
Delthyris.     See  Spirifer 
Delthyris  shaly  limestone,  559 
Deltodus,  692 

Demavend  (Mt),  296  (height) 
Denbighshire  grits,  563,  564 
Dendrerpeton,  682 
Dendrocrinus     Cambrensis,     481  ; 

Cincinnatiensis,   516  ;  retractilis, 

514 

Dendrodus,  625,  647 
Dendrograptus,    520 ;    gracillimus, 

516  ;    Hallianus,  477*  ;    tenuira- 

mosus,  516 
Dendrophis,  704 
Dendrophylla,  429* 
Denison  beds,  817,  837 
Denmark,  Cretaceous  in,  856,  857, 

858 
Density  of  the  earth,   15,  376;  of 

the     moon,      Mercury,     Yenus, 

Mars,  Jupiter,  16 ;  of  mountains, 

379 

Dent  de  Morcles,  profile  of,  367* 
Dent  du  Midi,  920 
Dentalina  priscilla,  690 
Dentalium,  424,  707  ;    attenuatum, 

917 ;  Meekianum,    690  ;     Missis- 

sippiense,    898*,   916 ;    sublaeve, 

675*,  690  ;  venustum,  647 
Denudation    by    the    atmosphere, 

159,  160*,  161*;  by  glaciers,  247- 

251 ;  by  water,  167-169,  177-189, 

186*,  451,  934 ;  by  waves,  217,  218, 

219,  221,  882 


Denudation,  relations  of  mountain 

ranges  to,  387-388 
Denver,  364 

—  group,  815,  825,  827,  828,  829,  830, 
839,  847,  856,  875 

Deoxidation,  124§,  127,  128;  de- 
structive effects  of,  125,  126*, 
127* ;  through  the  growth  of 
plants,  136 

Deposition,  by  glaciers,  247,  250; 
by  water,  169-170,  189-202,  216, 
628 ;  by  waves,  222  ;  by  winds, 
161 

Deposits,  ore.  See  Ore.  See  also 
Sediment 

Derbya  crassa,  690 

Derivation  of  Arachnids,  722-723 ; 
Limuloids  and  Crustaceans,  720- 
721 ;  Myriapods  and  Insects,  723- 
724 

Desatoya  Mts.,  757 

Des  Chutes  River,  894 

Deserts,  distribution  of,  50,  51 ; 
sands  of,  160,  161 

Desmatippus,  911,  912,  919 

Desmatochelys  Lowii,  849 

Desmids,  437§,  859;  in  hornstone 
or  flint,  582,  583*,  859 

Desmoceras  Breweri,  837 

Destruction  of  life.    See  Life 

Detritus,  75§,  81§,  167§ 

Devil-fishes,  424 

Devonian  (or  Devonic)  era,  575; 
North  American,  575  ;  Oriskany, 
577;  Corniferous,  579 ;  Hamilton, 
592 ;  Chemung  (with  Catskill), 
602;  foreign,  622;  geological  and 
geographical  progress,  628 ;  bio- 
logical, 630 ;  upturning,  630 

—  relations  of  the  Lower  Helder- 
berg  fauna,  the  Hercynian  ques- 
tion, 569-570 

Diabase,  87§,  273,  319,  325,  339, 453, 
457,  468,  469,  518,  748,  802 

Diabase-schist,  87§ 

Diablerets,  920 

Diablo,  Mt.,  835,  892 

Diaclases,  113§ 

Diacodon,  918 

Diadema,  59 

Diallage,  88 ;  rock,  87 ;  structure, 
321 

Diamond,  62,  64,  319,  455 

Diamond  Head,  Oahu,  271* 

Diamond  Mt.,  733 

Diaspore,  320 

Diatom  ooze,  57,  143 

Diatoma  vulgare,  699 

Diatomaceous  earth,  889 

Diatoms,  56,  57,  60,  64,  72,  81, 121, 
135,  136,  140,  142,  143,  152,  153, 
163,  164*,  229,  319,  433*,  436,  437*, 
699,  817,  859,  887,  895 ;  in  flint, 
582,  583* 

Diatryma  gigantea,  902 

Dicellocephalus,  477,  478,  481,  483, 
500,  502,  503,  516 ;  lowensis,  479*  ; 
Minnesotensis,  478,  479* 

Diceras,  780,  877  (end) ;  arietinum, 
780*,  790 ;  Lonsdalei,  865 

Diceratherium,  911,  918 

Diceratian,  790 


Dichobune,  926 ;  cervinum,  926 
Dichocrinus,  646      • 
Dichodon,  926 ;  cuspidatus,  926 
Diclonius  mirabilis,  846 
Dicotyles,  54,  1002  ;  nasutus,  1000 ; 

Pennsylvanicus,  1012 
Dicranograptus  ramosus,  510*,  515, 

516 

Dicranophyllum,  673 
Dictyocaris,  567 
Dictyocha,  894*  ;  crux,  894* 
Dictyo-cordaites  Lacoei,  610* 
Dictyonema,  481,  550,  590 
Dictyonema  shales,  482 
Dictyoneura     anthracophila,    701*, 

702,    704;    Humboldtiana,    703; 

Monyi,  702 
Dictyophyton,    432 ;      tuberosum, 

611*,  621    _ 
Dictyopteris,  699 
Dictyorhabdus  priscus,  509* 
Dicynodon,  707,  737,  778 
Didelphis,  925 
Didelphodus,  918 
Didelphops,  853* ;  comptus,  853* ; 

ferox,  853*  ;  vorax,  853* 
Didelphys,  55,  910,  918 
Didus  ineptus,  54,  1014 
Didymictis,  917,  918 
Didymites  globus,  774  ;  tectus,  774 
Didymograptus,  520  ;  extensus,  500 
Dieconeura,  691 
Dielasma,      642 ;     bovidens,    690 ; 

elongata,  707  ;  hastata,  700* 
Dikes,  90,  262*,  264,  298§,  299*,  302, 

327§ 

Diloma  ruderata,  927 
Dimetian  period  of  Hicks,  457 
Dimetrodon,  688 
Dimorphodon,  788 
Dinarites  Liccanus,  778 
Dindymine,  521 
Dinichthys,     603,    618;      Hertzeri, 

617*,  619  ;  Gouldi,  619 
Dinictis,  911,  918 
Dinoceras,  907§  ;    size  of  brain  of, 

914*  ;  mirabilis,  907 
Dinoceras  beds,  886 
Dinophis,  901 
Dinornis,  54,  1014,  1019  ;  giganteus, 

54,  1014 

Dinosaurs,  Triassic,  741,  751 ;  Ju- 
rassic, 760,  768,  785,  796  ;  Cre- 
taceous, 816,  828,  836,  844*,  856, 

863*,  867,  870 ;  relation  to  Birds, 

796 
Dinotherium,  927 ;  giganteum,  924, 

925* 

Dinotosaurus,  785 
Dionide,  521 
Dioonites,  832 ;  borealis,  833  ;  Buch- 

ianus,  832*,   834;    Columbianus, 

834 ;  Dunkerianus,  834 
Diopside,  318,  328 
Dioryte,  86§,  97* ;  schist,  86§ 
Diospyros,  922 
Dip,  99§*,  105,  114* 
Dipeltis  diplodiscus,  691 
Diphya  limestone,  791 
Diphyphyllum,    550,    640;    arundi- 

naceum,    591 ;    fasciculum,    592  ; 

stramineum,  591 


INDEX. 


1053 


Diplacodon,  90T,  918 

Diplacodon  beds,  886 

Diplaspis  Acadica,  546 

Diplocynodon  victor,  767* 

Diplodocus  longus,  762* 

Diplodonta  acclinis,  917 

Diplodus,  687,  692 ;  compressus, 
692 ;  Gaudryi,  702 ;  gracilis,  692 ; 
latus,  692 

Diplograptus,  520 ;  amplexicaulis, 
505*,  514;  inucronatus,  510*; 
pristis,  510*;  spinulosus,  516; 
Whitfieldi,  516 

Diploopoda,  419 

Diplopterus,  627 

Diplurus  longicaudatus,  751 

Dipnoans,  417§ ;  Paleozoic,  587, 
588*,  617*,  618,  619,  625*,  725, 
727;  post-Paleozoic,  736;  Per- 
mian, 687 ;  Triassic,  772,  869 

Dipnoi,  54,  59,  417 

Dipriodon  lunatus,  853* 

Diprionidae,  498*,  499§ 

Diprotodon  Australia,  1006* 

Dipterocaris  penna  -  Daedali,  615*  ; 
Procne,  615* 

Dipters,  419,  679,  783,  794,  900 
(number  of  Florissant) 

Dipterus,  625,  627  ;  macrolepidotus, 
625* ;  Sherwoodi,  617* 

Disappearance  of  life.    See  Life 

Discina,  59,  72,  425§,  447,  475,  481, 
482^  487  ;  Caerfaiensis,  481 ;  lamel- 
losa,  427* ;  Lodensis,  627 ;  trun- 
cata,  612,  620 

Discinids,  779,  922 

Discinisca  lamellosa,  427* 

Discites,  591,  602,  642,  700 

Disco  Bay,  244,  350 

Disco  Island,  272,  376,  819,  831,  921 

Discosorus,  546,  549 ;  conoideus,  546 

Dismal  Swamp,  154,  889 

Displacements  through  frost,  230, 
231*.  See  also  Faults ;  Flexures  ; 
Fractures 

Dissacus,  917,  918 

Distortions  of  beds  and  fossils,  107, 
369,  370*,  371 

Distortrix  septemdentata,  916 

Disturbances,  351  §,  363, 406 ;  of  clos- 
ing Archaean,  466 

Dithyrocaris  Belli,  602  ;  carbonaria, 
691 

Ditroyte,  85§ 

Dockum  beds,  660 

Docodon  striatus,  767* 

Dodo,  54,  1014* 

Dosdicurus,  1017 ;  clavicaudatus, 
1003 

Dog,  924 

Doggers  of  the  Oolyte,  775,  776 

Dolatocrinus,  590 

Doleryte,  78,  85,  87§ 

Dolichopterus,  557 

Dolichosaurs,  870 

Dolichosoma,  692 ;  longissimum, 
704 

Dolomite,  68*§ 

Dolomization.  See  Dolomyte,  mak- 
ing of 

Dolomyte,  78§,  79§  ;  making  of,  133, 
134,  343,  524 


Dolphin  shoal,  19,  20,  217 
Dolphins,  912 

Domatoceras  umbilicatum,  691 
Dombeyopsis  obtusa,  839 ;    squar- 

rosa,  839 
Domnina,  918 
Donax,  916 
Dordonian,  859,  866 
Doropyge,  482 

Dorycrinus  unicornis,  640*,  646 
Dosinia,  916 ;  acetabula,  917 
Dosiniopsis  lenticularis,  915  ;  lenti- 

cularis  var.  Meekii,  897* 
Double  Mountain  beds,  660 
Drainage,  antecedent,  consequent, 

superimposed,  203§  ;  reversed.  947 

—  courses,  direction  of,  177,  888 
Drepanacanthus,  692 ;  anceps,  692 
Drepanis  Pacifica,  1014 
Drepanocheilus  Americanus,  841* 
Drepanophycus,  590 

Drift,  184,  916,  942 

Drift-sand  hills,  94,  161, 162,  213 

Dripstone,  79§,  131 

Dromaeus,  54 

Dromatherium,  754,  768,  773;  syl- 
vestre,  754* 

Dromopus,  682 ;  agilis,  684* 

Dromornis,  1019 

Drumlins,  942 

Drummond  Island,  542 

Dry  Creek,  Wyoming,  907 

Dryolestes  priscus,  767*;  vorax, 
767* 

Dryopithecus,  927 

Dryptodon,  917 

Duckbill,  53,  415 

Dudley  limestone,  563 

Dugong,  925 

Dundas  gorge,  946 

Dunes,  162§,  265 

Dunvegan  beds  (group),  830,  840 

Dunyte,  89§ 

Dust,  transportation  of,  159,  195; 
showers  of,  163,  164* ;  on  gla- 
ciers, 235,  241 

Dwyka  bowlder  bed,  699 

Dyas.    See  Permian  period 

Dyke.     See  Dike 

Dysaster  ovulum,  865 

Dysintrybyte,  84 

Dystrophseus  Viaemalae,  758 

Eager,  212§,  215 
Eagle,  902 

—  Ford  shales,  815,  824,  854 

—  Pass  beds,  824,  855 

—  ray,  643 

Earth,  15  (density),  376  (specific 
gravity) ;  general  contour  and 
surface  subdivisions,  15-30 

Earth  as  an  individual,  9,  10,  393; 
relation  of  to  the  universe,  10 ; 
proportion  of  land  and  water,  16 ; 
system  in  the  courses  of  feature 
lines,  35-42,  393 

— ,  changes  in  the  ellipticity  of  its 
orbit,  254,  255  ;  in  the  position  of 
its  axis  of  rotation,  255,  346 ;  its 
circumference  shortened  in  moun- 
tain-making, 391 ;  heat  reached 
the  surface  in  three  ways,  258 


Earth,  polar  diameter  maximum 
and  minimum,  1027 

— ,  development  of,  391,  1027^ 
thickness  of  the  supercrust,  209, 
377 

Earth-shaping,  mountain-making,, 
and  attendant  phenomena,  345- 
396  (changes  of  level,  345;  dis- 
turbed regions,  351 ;  typical 
mountain  ^ranges,  353  ;  subordi- 
nate effects  of  orographic  move- 
ments, 369  ;  origin  of  the  earth's 
form  and  features,  376) 

Earth  (soil),  75,  76§,  137  (nitrifica- 
tion) 

Earth-worm,  156,  423 

Earthquake  waves  (oceanic),  218,. 
221,  875 

Earthquakes,  222,  229,  265,  286,  287, 
344,  349,  372-375,  386,  875  ;  cause 
of  exterminations,  877 ;  geolo- 
gical effects,  375 ;  not  essential  in 
volcanic  eruptions,  286 

East  Indies,  17,  19,  21,  44,  145> 
(coral  reefs)  ;  trends  of  the  islands, 
38,  39,  40;  volcanoes,  295,  296, 
297 

East  River,  Pictou,  533,  543 

East  Rock  dike,  299*,  302*,  303, 
312,  804,  806 

Eastern-border  life  of  N.  America 
related  to  European,  572-573 

—  Interior  region  of  N.  America, 
576,  578,  633,  636 

—  Sea  of  N.  America,  537,  539, 
541,  558,  571,  575,  579,  580,  628, 
629,  633,  734 

Eatonia,  562,  579;  medians,  579; 
peculiaris,  579;  singularis,  560*, 
562 

Ebb-and-flow  structure,  93§* 

Ecca  beds,  698,  699,  770 

Eccentricity  cycle,  influence  of,  on 
climate,  254,  978,  1027 

Eccyliomphalus  priscus,  500 

Echidna,  53,  415§,  795,  798 

Echinids,  59 

Echinocaris,  599,  615;  Beecheri,. 
621 ;  punctata,  600* ;  socialis,  621 ; 
Whitfieldi,  621 

Echinoderms,  59,  130,  140,  144,  158, 
418,  419,  427§,  428*,  429*,  430;. 
Cambrian,  469,  480;  Calciferous, 
499,500 

Echinognathus  Cleveland!,  513* 

Echinoids,  428*§,  429*,  430§,  525, 
641* 

Echinosphaerites,  520,  521 

Echinus,  157,  427,  428*§,  429*, 
879 

Echo,  360*,  362 

Echo  Cliffs,  363* 

Eclogyte,  88§ 

Ecphora  quadricostata,  899*,  917 

Ectacodon,  918 

Ecuador,  935  (heights) 

Eddies,  184§ 

Edentates,  54,  919,  924  (first),  927 

Edestosaurus,  826  ;  dispar,  849* ; 
velox,  848* 

Edestus,  680  ;  giganteus,  680,  681*;. 
minor,  680,  681* 


1054 


INDEX. 


Edmondia,  621,  622 

Edriocrinus,  562,  577 ;  sacculus,  579 

Egan  Kange,  365 

Eggs,  fossil,  787 

Egypt,  160, 162 ;  Cretaceous  of,  857 ; 
Tertiary  of,  920 

Eifel,  289,  297,  568,  602,  627,  938 

Eifelian  beds,  626,  627 

Eiger,  236 

Eileticus  anthracinus,  691 

Eteolite,  65§,  85,  449 ;  syenyte,  532, 
876 

Elasmobranchs,  587 

Elasmosaurus,  845  ;  platyurus,  845 

Electric  Peak,  987 

Elephant,  54,  402,  903,  924,  925,  927, 
931 

Elephas,  927  ;  Africanus,  1016 ; 
Americanus,  998 ;  antiquus,  927, 
1006;  Columbi,  1001  ;  Melitensis, 
1006 ;  meridionalis,  927  ;  primi- 
genius,  966*,  997,  1000, 1004, 1005, 
1006,  1009',  1015 

Elgin  sandstones,  773 

Elginia  mirabilis,  773 

Elizabeth  Island,  elevation,  350 

Elk,  950  (migration) 

Elk  Mountain  sandstone  and  shale, 
606 

Elk  Mts.,  106*,  363,  364*,  689 

Ellipsocephalus,  482 

Elm,  435,  837 

Elotherium,  909,  911,  918  ;  crassum, 
909* 

Embryonoid,  423 

Emerald  Island,  39 

Emery,  64§,  455 

Emeu,  54 

Emigrant  Peak,  937 

Empo,  843 

Emys,  901,  926 

Enaliornis,  864 

Enaliosaurs,  682,  760 

Enallaster,  834  ;  Texanus,  834*,  836 

Encephalartos  denticulatus,  756* 

Encephalaspis,  588 

Enclimatoceras  Ulrichi,  896*,  915 

Encrinal  limestone,  543,  559,  593, 
638,  728 

Encrinites,  429§,  430,  559 

Encrinurus,  515,  521,  551,  552  ; 
Isevis,  569  ;  punctatus,  565*,  567, 
568  ;  variolaris,  565*,  567 

Encrinus,  719  ;  liliiformis,  429*,  770, 
771*,  774 

Endoceras,  501,  506,  508,  511,  514§, 
516,  520,  591  ;  proteiforme,  514, 
516 

Endogenous  work,  867 

Endogens,  434§,  435 

Endolobus  gibbosus,  691  ;  spec- 
tabilis,  642 

Endothyra  Baileyi,  646 

England,  19,  32,  48,  162,  219,  234, 
256,  297  (volcanoes),  874  (earth- 
quakes), 431,  464,  760;  disturb- 
ances and  upturnings  in,  534,  630, 
733  ;  geological  map  of,  693,  694* 

— ,  Archaean  in,  456 ;  Cambrian, 
480,484 

Engonoceras  Gervillianum,  865 

Enhydriodon,  927 


Enhydrocycn,  918 

Enneodon  crassus,  767* 

Enniskillen  oil  wells,  581 

Enstatite,  67§,  88 

Entolium,   760;  avicula,  690;  gib- 

bosum,  759* 
Entomis,  567,  621 
Entomostracans,    420§,    421,    423, 

439§,  525,  574 

Eocarboniferous  period,  632 
Eocene  lakes  of  N.  America,  882, 

893,  894,  929,  933 
Eocene  period.     See  Tertiary 
Eocystites,  474 ;  longidactylus,  474* 
Eodevonian,  576§ 
Eogene,  880§ 

Eohippus,  905,  918  ;  pernix,  905* 
Eohyus,  918  ;  distans,  907 
Eolian,  159§ 
Eolian    formations,    characteristics 

of,  162 

Eolian  limestone,  491,  517,  528 
Eolignitic,  885,  888 
Eolus,  Mt.,  530* 
Eopaleozoic   time,   407,  460§,  462- 

535,  716 

Eophrynus  Prestwichii,  703 
Eophyton,  482 
Eophyton  sandstone,  4*82 
Eosaurus  Acadianus,  682,  683* 
Eoscorpius       carbonarius,       678* ; 

"Woodianus,  691 
Eospongia  Rcemeri,   503 ;    varians, 

503 

Eozoic,  442 
Eozoon,  319,  454,  455;  Bavaricum, 

455 ;  Canadense,  454* 
Eparchaean,  446 
Epeirogenic  movements,  376§,  388, 

392  ;  of  the  Tertiary,  933-937  ;  of 

the  Quaternary,  1020 
Ephedra,  435 
Ephemera,  600 
Ephemerids,  600 
Ephippioceras  divisum,  691 
Epiaster  elegans,   837 ;  polygonus, 

865 
Epicentrum  of  an  earthquake,  374§, 

375 

Epidosyte,  88§ 
Epidote,  66§,   82,  85,  88,  312,  315, 

318,  331  ;    gneiss,  88 ;  rocks,  88, 

89 

Epihippus,  912,  918 ;  gracilis,  907 
Epipodite,  422§ 
Epithemia  Argus,  163,  164*  ;  gibba, 

163,    164*,    699;    gibberula,    163, 

164*  ;  longicornis,  163,  164* 
Epoch,  406§ 
Eporeodon,  911,  918 
Epsom  salts,  555 
Epsomites,  555 
Equiseta,   434,  436§,  560,  663,  667, 

672,  711 

Equisetites,  685  ;  rugosus,  704 
Equisetum,   74  (ash),  519;    arena- 

ceum,  773 ;  arvense,  74 ;  hyemale, 

75 ;  telmateia,  74,  75 
Equivalence    of    strata,    398,    401, 

815 
Equus,  913*,  919,  927,  1002 ;  cabal- 

lus,    1004,    1005;    excelsus,   999; 


fraternus,  1001 ;  major,  1001, 1002  ; 
simplicidens,  912 ;  Stenonis,  927 

Equus  beds,  892,  1000 

Eras,  406§;  reality  and  character- 
istics of  geological,  397 

Erebus,  Mt.,  296  (height) 

Eremopteris,  689,  699 

Erian,  576§,  590 

Erie  clays,  972 

Erie,  Lake,  200,  947,  986 

Erie  shale,  606 

Erinaceus,  927 

Eriptychius  Americanus,  509* 

Erosion,  258,  300,  388,  390,  533,  647, 
709,  827,  828,  868,  875,  894,  934; 
by  carbonated  water  with  humus 
acids,  129;  by  drift  sands,  160; 
by  rivers,  167,  178, 181*,  183*,  195, 
196*,  943;  by  water  containing 
carbonic  acid,  130,  131 ;  in  the 
Carboniferous,  709 ;  causing  un- 
conformability,  115,  116.  See  also 
Denudation 

— ,  Monument  Park,  186* 

Eruptions.    See  Igneous  ;  Volcanic 

Eruptive  rocks,  76§,  265§ 

Eryon  arctiformis,  783* 

Eryops  megacephalus,  686*,  687 

Eschara,  425*,  427 

Eskers,  942,  970 

Esopus  millstones,  542 

Estheria,  600  (oldest  known),  623, 
774;  minuta,  771*,  773,  774; 
ovata,  750* ;  pulex,  600 

Estheria  shales,  771 

Esthonia,  Cambrian  in,  482,  484 

Esthonyx,  917,  918 

Estuary  deposits,  191 

Ethmophyllum,  483 

Ethmosphsera,  319 

Ethylene  oils,  124 

Etna  (Mt.),  26,  279 

Etoblattina,  691,  701 ;  primseva, 
701*,  704  ;  venusta,  679* 

Eua  Island,  elevation,  350 

Eucalyptocrinus  decorus,  550,  551, 
567,  568 

Eucalyptus,  838*  ;  Geinitzi,  838* 

Euchasma  Blumenbachii,  500 

Eucryptite,  321 

Eucryte,  87§ 

Eucyrtidium  Mongolfleri,  433* 

Eudialyte,  85 

Eugereon  Bockingi,  722 

Eulima  Texana,  855 

Eumetria  Verneuiliana,  642*,  646 

Eumicrotis  curta,  757,  760 

Eumys,  918 

Eunella  Sullivanti,  601 

Eunema,  514 

Eunice,  423 

Eunotiaamphioxys,  163, 164*  ;  gran- 
ulata,  163,  164*;  Itevis,  163,  164*; 
tridentula,  163,  164*;  zebrina, 
163,  164*  ;  zygodon,  163,  164* 

Euomphalus,  520,  562,  586,  590,  598, 
625,  642,  700,  704;  alatus,  567; 
annulatus,  601 ;  cyclostomus,  602 ; 
funatus,  568 

Eupachycrinus,  690 

Eupagurus,  59  ;  longicarpus,  994 

Eupelor  durus,  751 


INDEX. 


1055 


Euphantaenia,  432 

Euphoberia,  691,  701 ;  anthrax,  T03  ; 

armigera,  678*,  691 ;  Brownii,  703 
Euphotide,  88§ 

Euplectella,  482  ;  speciosa,  57*,  432 
Euproops  Dana?,  691 
Eupterornis,  925 
Eurasia,  17,  21,  22,  32,  33,  51,  538 ; 

sea  level  at  its  center,  346 
Eureka  district,  447,  469,  478,  484, 

495,  516,  541,  580,  581,  592,  593, 

659,  733  ;  mine,  340  ;  quartzyte, 

516 ;  shale,  606 

—  Mts.,  733 

Europe  (see  also  Eurasia),  22,  28 
(mean  height),  24,  26,  32,  34,  41 
(trends),  51,  165,  234  (snow-line), 
296  (volcanoes),  393,  395,  398,  402, 
403,  405,  406,  407,  411,  760,  793 
(warmed  by  the  Gulf  Stream), 
913  ;  American  types  in,  550, 573  ; 
Australian  types  in,  922 

— ,  Archaean  in,  442, 456 ;  Cambrian, 
484  ;  Carboniferous,  631,  674,  689, 
691,  692,  699  ;  contrast  of  Juras- 
sic with  American,  792 ;  Lower 
Silurian,  upturnings  at  the  close, 
533-535 

Euryapteryx,  1014 

Eurylepis,  679,  680,  692  ;  tubercu- 
lata,  680*,  692 

Eurynotus,  417 

Eurypterids,  59,  420§,  496,  565,  623, 
719,  721  ;  Devonian,  604,  615, 
623*,  629,  719  (culmination) ;  Car- 
boniferous, 676,  701,  710,  719  ; 
Lower  Silurian,  496  (first),  521, 
525,  719;  Upper  Silurian,  550, 
571,  574;  Onondaga,  556*,  557; 
Paleozoic,  420,  719,  723 

Eurypterus,  557,  567,  615,  623,  722, 
724 ;  giganteus,  556  :  Mansfieldi, 
676,  677*,  710  ;  prominens,  550  ; 
remipes,  556* 

Euryte,  S4§,  205 

Eusarcus,  557 

Eusthenopteron,  619  ;  Foordi,  618* 

Eutaw  beds  (group),  815,  816,  819, 
854  ;  (Upper),  815,  823 

Eutoptychus,  918 

Everest  (Mt.),  23 

Evergreen  trees,  435 

Evolution.  See  also  Life,  progress 
of 

Evolution  by  Natural  Selection, 
1030,  1032 

—  and  cephalization,  439 
Excavation  by  water,  167§,  178 
Excrements,  fossil.     See  Coprolites 
Exmouth  Isl.,  749,  792 
Exogens,  434§,  435 

Exogyra,  160,  779,  834,  840,  856,  860, 
877  (end) ;  arietina,  885*,  837  ; 
Boussingaultii,  867 ;  columba, 
866  ;  columbella,  854,  855  ;  conica, 
865  ;  costata,  841*,  854,  855 ; 
Couloni,  865 ;  flabellata,  836 ; 
laevigata,  867  ;  ponderosa,  834, 
855 :  sinuata,  837,  864,  865 ;  sub- 
plicata,  867 ;  Texana,  817,  836 ; 
virgula,  780* 

Exogyra  arietina  clays,  817 


Exogyra  ponderosa  marls,  815,  824, 

855 
Expansion  and  contraction.  259-265, 

372,  381 

Exploits  River  channel,  461 
Exploring  Isles,  150 
Extermination  of  species.    See  Life 
Extracrinus  Briareus,  778*,  790 

Facial  suture,  421§ 

Fagus,  896,  922  ;  ferruginea,  895*, 
896 

Fairweather,  Mt.,  25,  238 

Falkland  Islands,  19,  155,  209,  627 

Faluns  beds  of  Anjou,  926 

Famennian  beds,  626,  627 

Fanning  Islands,  38 

Faroe  Islands,  938 

Fasciolaria,  916,  922 ;  buccinoides, 
841*  ;  rhomboidea,  917  ;  scalarina, 
917 

Fats  (animal),  123, 124,  655,  656 

Faults,  107§,  108*,  109*,  110*,  111, 
114*,  115*,  353;  in  the  Great 
Basin,  365,  366* ;  Taconic,  527*  ; 
Appalachian,  354 

Fauna  antiqua  Sivalensis,  936 

Faunas.     Seo  Life 

Favistella,  552;  favosidea,  550; 
stellata,  510,  511*,  515 

Favosites,  310,  547*§,  552,  562,  567, 
581,  585§,  597,  625,  640,  719  ; 
arbuscula,  601  ;  Argus,  601 ; 
basalticus,  551,  591  ;  Canadensis, 
592  ;  cervicornis,  562,  625  ; 
favosus.  550:  fibrosus,  520,  522, 
567,  568,  628;  Goldfussi,  584*, 
590  ;  G^othlandicus,  550,  551,  552, 
567,  568,  569,  591;  Hamiltonise, 
601  ;  Helderbergia?,  560,  562  ; 
hemisphaericus,  592 ;  Niagarensis, 
547*,  55d";  placenta,  601  ;  poly- 
morphus,  569  ;  reticulatus,  623  ; 
turbinatus,  590  ;  venustus,  550 

Faxe  chalk,  866 

Fayalite,  67§,  84,  338 

Feature-lines,  system  in  courses  of, 
35 

Feldspar,  64*§,  129 

Feldspathic  rocks,  80,  81,  82 ;  veins, 
331,  332,  336 

Felis,  919,  927,  1001 ;  atrox,  1000 ; 
leo,  1004  ;  pardoides,  927  ;  spelsea, 
1004,  1006,  1009 

Felsitic,  88 

Felstones,  517 

Felsyte,  82,  84§  ;  porphyry,  468,  623 

Fenestella,  545,  546*,  551,  590  ;  cel- 
sipora.  579  ;  prisca,  546*,  550 

Fermentation,  137 

Fernandian,  446 

Fernando  de  Noronha,  phonolyte 
peak,  263* 

Fernando  Po,  297 

Ferns,  53,  434,  436 ;  ash  of,  74,  75, 
663  ;  Silurian,  564,  565  ;  Devonian, 
583*,  595*  ;  Subcarboniferous,  639, 
645  ;  Carboniferous.  654,  657,  666, 
667,  670*,  671*,  676.  677,  682,  689 ; 
Permian,  684,  685,  704  ;  Triassic, 
740,  749*,  750,  770 

Ferriferous  limestone,  664,  792 


Ferruginous  clay,  81§ ;  rocks,  78§  ; 

sandstone,  80 
Fibrolite,  65§,  66,  83 
Fibrolitic  rocks,  83 
Fichtelgebirge,  563,  627 
Ficophyllum,  831 
Ficus,  831,  840,  916 ;  auriculata,  839 ; 

lanceolata,  839  ;  occidentals,  839  ; 

planicostata,     839 ;      spectabilis, 

839  ;  tilisefolia,  839  ;  Virginiensis, 

832* 

Fig,  812,  859,  921 
Fiji  Islands,  145,  148,  150*.  297 
Fin-spines,  416*§, 
Findlay,  Ohio,  533 ;  oil-region,  138, 

206,  522-523  ;  yield  of,  523 
Finland,    Archaean    In,    455,    456; 

Lower  Silurian,  521 
Finsteraarhorn,  236 
Fiords,  946-949  (Glacial) 
Fioryte,  82§ 
Fire  clay,  650 
Fire-Hole,  305,  307 
Firn,  233§ 

Fish,  primitive,  related  to  the  Lam- 
prey, 1031 

Fish  Creek  Mts.,  495,  733 
Fish-oil  in  shales,  655,  656 
Fish-scales,  composition  of,  73 
Fisher  Island,  822 
Fishes,  52,  55,  56,  59,  60,  141,  146, 

156,  158,  176,  409*,  414,  415-418, 

564,  681,  789,  797,  931 ;  fossil,  in 

oil-yielding  coal-beds,  124;  reign 

of,  411,  460  ;  earliest  known,  509 ; 

culmination  of,  869  ;  first  Teleosts, 

73S 

Flabellaria,  921 ;  eocenica,  839     • 
Flabellina  rugosa,  432*,  860* 
Flagellates,  419,  431 
Flagging-stone,  92§,  480 
Flaming  Gorge  group,  747 
Flamingoes,  923 
Flammenmergel,  865 
Flat-pebble  conglomerate,  604,  630 
Flathead  Paver,  240 
Flexure-faults,  109*,  351 
Flexures,  99,  101*,  102*,  103*,  104*, 

105*,  106*;   variations  in,    from 

pressure,  369;   in  the  Alps  and 

Juras,  367,  368 
—.Appalachian,    354,    355*,    356*, 

649*,  650*  ;    Taconic,  527* ;  Wa- 

satch,  361,  369 
Flies,  419,  794 
Flint,   63§,  97,  859§ ;  implements, 

143,  1008 
Flocculation,  170 
Flood-grounds  of  rivers,  181§,  182, 

183,  191,  193-194,  943.    See  also 

Shore-platforms  ;  Terraces 
Flora.    See  Plants 
Florida,  22,  23  (height),  40  (trend), 

153,  210,  213,  265,  323,  433,  823  ; 

coral  reefs,  145,  153,  213 
— ,  Tertiary  in,  881*,  884,  887,  890, 

891,  892,  916,  934  (elevation) 

—  Banks,  163 

—  seas,  Nullipores  in,  147 

—  Strait,  44,  45,  229,  230,  256 
Floridian  epoch  and  beds,  884,  891, 

900*,  917 


1056 


INDEX. 


Florissant  group  or  basin,  886,  893, 

900,  901,  902 
Flotation  crust,  378§ 
Flow-and-plunge    structure,    93*§, 

194 

Flow  of  solids,  351-852 
Flowerless  plants.    Bee  Cryptogams 
Fluccan,  453 

Fluidal  structure  in  rocks,  77§ 
Fluor-apatite,  73 
Fluor  spar.     See  Fluorite 
Fluorides,  69,  73,  143 
Fluorine,  61,  63 
Fluorite,  fluor  spar,  63,  69§ 
Flustra,  427 
Fluvial  action,  744 ;  formations,  191, 

192,  820.    See  also  Alluvial 
Flysch,  367*,  920 
Folds.     See  Flexures 
Foliated  rocks,  77§,  309,  534 

—  structure,   foliation,   112,   113*§, 
312,  370-371 

Folkestone  beds,  865 

Fontainebleau  sandstone,  318,  926 

Foosdiceras  bidorsatum,  774 

Foot  wall,  328§ 

Footprints  (tracks,  trails),  89,  95, 
223;  Cambrian,  446,  464,  469, 
474,  477*,  479*,  480,  482 ;  Upper 
Silurian,  544,  545*,  546*;  Car- 
boniferous, 681,  682,  684*,  692; 
Subcarboniferous,  644,  645*  ;  Tri- 
assic,  742,  745,  750*,  751*,  752*, 
753,  755,  772* 

Foraminifers,  57,  72,  432*,  454,  502, 
840,  858,  860,  922 

Fordilla  Troyensis,  472* 

Forest  bed,  927 

—  Marble,  775,  790 
Forests,  155 ;  buried,  135,  887 
Formation,  90§ 
Formicidse,  901 

Formosa,  40 

Fort  Benton  group,  825,  829,  843, 
855 

—  Bridger,  886 

—  Pierre  group,  815,  825,  829,  830, 
855 

—  Tejon,  885 

—  Union  beds  (group),  828,  830 

—  Worth  limestone,  817,  837 
Fossil  wood.    See  Wood,  silicified 
Fossiliferous  rocks,  309,  400,  408 
Fossilization,  methods  of,  142     ' 
Fossils,  12§,  71§,  141 ;  as  means  of 

correlation,  400^04  (precautions, 
402-404),  405;  distortion  of,  107, 
869,  370*,  371;  obliterated  by 
metamorphism,  314 ;  silicified, 
130,  135,  160,  323 

Fox,  927 

Fox  Hills  beds  (group),  815,  825, 
828,  829,  840,  842,  852,  855 

Foyayte,  85§ 

Fractures,  106, 107,  108*,  109*,  110* 

—  and  displacements  from  pressure, 
352*,  353*,  371,  807 ;  from  freezing 
water,  230,  231 ;  from  variations 
in  temperature,  260 

Fragillaria  Harrisoni,  699 ;  pinnata, 

164*,  165 
Fraginental  deposits,  76,  89 


France,  87,  167, 176,  297  (volcanoes), 
734  (upturnings) 

— ,  Archaean  in,  456;  Cambrian, 
484;  Lower  Silurian,  518,  521; 
Upper  Silurian,  564,  566,  568,  569, 
573;  Devonian,  626 ;  Subcarbonif- 
erous, 693;  Carboniferous,  693, 
696,  702 ;  Permian,  698  ;  Triassic, 
768,  769,  774 ;  Jurassic,  774,  775, 
792, 793  ;  Cretaceous,  774,  856, 857, 
859,  865,  866,  870;  Tertiary,  919, 
920,  921,  923,  924,  925,  926,  932 

Franconia,  738,  769,  773 

Franconian,  738,  769,  773 

Franklinite,  70§,  449 

Frasnian  shales  and  limestone,  626 

Frasnian  stage,  601 

Fraxinus  denticulata,  839  ;  eocenica, 
839 

Fredericksburg  epoch  (group),  815, 
817,  819,  836 

Frederikshaab  Glacier,  240,  241* 

Freeport  coal,  652,  657,  663;  lime- 
stones, 652 

Freezing,  effects  of,  230 

Freiburg  vein,  333 

French  chalk,  67 

Frenela,  922 

Friendly  Islands,  19,  20,  296,  392 

Frigid  zone,  46§ 

Fringing  reefs,  148*,  149*,  150*, 
151 

Frisco,  Utah,  340 

Frobisher  Bay,  495 

Frog,  54,  415,  418,  681,  795 

Frog  Mt.,  Ala.,  577 

Frog-spittle,  437 

Frome  group,  831 

Frondicularia  annularis,  432* 

Front  Range  of  Colorado,  24,  25,  29, 
203,  359,  363,  389,  580,  739,  747, 
827,  829,  893,  935 

Frost  causing  displacement,  157, 
231* 

Fruits,  Carboniferous,  668,  669*, 
672*,  673*,  674;  Subcarbonifer- 
ous, 639  ;  Tertiary,  896*,  921 

Fucoides  Harlani,  549 

Fucus,  75,  437 

Fuegia,  154,  296;  Cretaceous  in, 
858;  snow  line  in,  234;  glaciers 
on,  240 

Fujiyama,  volcano  of,  290 

Fulgur  spiniger,  916 

Fulgurite,  265§,  266 

Fuller's  earth,  775,  790 

Fumaroles,  82,  265,  293§,  294 

Fundamental  Gneiss,  408§,  440 

Funeral  Mountains,  23 

Fungi,  75,  136,  158,  434,  436§,  441, 
454,  688 

Fungoid  plants,  63 

Fusibility  of  igneous  rocks,  273, 
304;  its  degree  determining  the 
character  of  volcanic  phenomena, 
273,  274 

Fusion,  cooling  from,  261*,  264 

Fusispira  elongata,  515;  terebri- 
formis,  516;  ventricosa,  515 

Fusulina,  433,  659,  674,  696 ;  cylin- 
drica,  432*,  674*,  690,  700  ;  elon- 
gata, 690  ;  gracilis,  690 ;  Japonica, 


700;  robusta,    690;    ventricosa,. 
690 

Fusus,  130,  916,  922;  exilis,  917; 
interstriatus,  915 ;  Labradorensis, 

984;  parilis,     917;     pearlensis, 

916 ;  strumosus,  917  ;   tornatus, 
984 

Gabbro,  87§,  88 
Gadolinite,  449 
Gadus,  916 
Galathea,  703 
Galdhopig,  32 
Galena,  70§,  125§ 

—  limestone,    342,    492,    494,    518, 
514,  515,  522 

Galeocerdo,  855  ;  latidens,  926 

Galerites,  860 

Galerus,  916 

Gait  limestone,  543 

Galveston  Deep  Well,  890,  891 

Gambier  Islands,  150 

Gampsonyx  fimbriatus,  701*,  703 

Gangamopteris,  698 

Ganges,  delta  of,  378 ;  discharge  of,. 
173  ;  silt  of,  190 

Gangue,  69,  70,  331§,  333 

Gannet,  902 

Ganoids,  55,  59,  401,  402, 416§,  417*, 
418,  510 ;  structure  of  teeth,  417*, 
725;  Trenton,  509  (first),  574; 
Upper  Silurian,  574 ;  Devonian, 
587,  589*,  618*,  619,  620,  625*, 
629  ;  Subcarboniferous,  643,  700  ; 
Carboniferous,  679,  680*,  692,  698, 
702;  Permian,  687,  705;  Paleo- 
zoic, 725,  727  ;  post-Paleozoic,  736 ; 
Jurassic,  699, 783, 784* ;  Mesozoic, 
879;  Cretaceous,  812,  828,  843,. 
862,  863 ;  Tertiary,  922 

Ganorhynchus  oblongum,  621 

Gardeau  shale,  605 

Gardiners  River,  131, 132*  (springs),. 
133,  306,  307 

Garnet,  66*§  ;  rocks,  82,  88 

Garnetyte,  88§ 

Garonne,  191 

Gars.     See  Ganoid 

Garumnian,  859,  866 

Gas,  mineral.  See  Mineral  oil  and 
gas 

Gaspe,  88,  466,  533,  544,  554,  581,, 
593,  611,  630  (upturnings) 

—  limestone,  544,  580  ;  sandstones,. 
591 

Gaspe- Worcester  trough,  536,  537,. 
558,  559,  577,  633,  715,  732 

Gastornis,  925  ;  Edwardsi,  925 

Gastrochsena,  157 

Gastropods,  59,  130,  152,  157,  423§,. 
424§,  425* 

Gault,  815,  818,  837,  857,  858,  859,. 
865,  935 

Gavialis  Dixoni,  926 ;  fraterculus,. 
848  ;  Neocesariensis,  848 

Gavials,  54,  754,  787,  848 

Gavilian  Range,  892 

Gay  Head.    See  Martha's  Vineyard 

G6ant,  Glacier  du,  235*,  236,  238, 
242 

Geanticline,  Cincinnati.  See  Cin- 
cinnati uplift 


INDEX. 


1057 


Geanticlines,    106§,  364,  381,  582; 

corresponding    to    geosynclines, 

387,  892 

Gedinnian,  570,  626 
Gehlenite,  313 
Gemellaria  loricata,  427* 
Gemma  purpurea  var.  Totteni,  917 
Gems,  90,  327,  331 
Genentomum  validum,  691 
Genesee  beds,  594,  601 

—  epoch,  410 

—  Falls,  section  at,  91*,  542 

—  Eiver,  540,  542,  605 

—  shale,  581,   601,  728 ;  slate,  593, 
595 

Geneva,  Lake,  199,  202 

Geode  bed,  637 

Geodes,  97§,  98 

Geodia,  432* 

Geodiferous  limestone,  540 

Geogenic  work,  376§ 

Geoglyphics,  95§ 

Geographical  distribution  of  plants 

and  animals,  52-60 
Geolabis,  918 
Geoinys,  919 
George's  Shoal,  944 
Georgia,  23  (height),  24,  184,  373 

(earthquake),  872 
Georgian  Bay,  540 

—  period,  464 

Geosynclinal  movements  over  the 
oceanic  basins,  936-937 

Geosynclines,  106§,  199,  365  (Rocky 
Mts.),  380,  387 

Geothermic,  257§ 

Gerablattina,  691,  701 ;  balteata,  686 

Geralinura,  701,  723 ;  Bohemica, 
703  ;  carbonaria,  691 

Geraphrynus  carbonarius,  691 

Gerarus  Dana?,  679* 

Germany,  Paleozoic  in,  463;  Up- 
per Silurian,  563,  567  ;  Devonian, 
626,  627  ;  Subcarboniferous,  693 ; 
Carboniferous,  693,  696,  703,  704 ; 
Permian,  697,  698,  707,  722  ; 
Trfassic,  741,  769,  773,  774  ;  Ju- 
rassic, 774,  776,  793 ;  Cretaceous, 
774,  859,  865,  866  ;  Tertiary,  920, 
922,  923,  924,  925;  volcanoes  in 
Upper  Silurian,  296 

Gervillia,  759  ;  acuta,  790  ;  anceps, 
865  ;  bipartita,  774  ;  costata,  773  ; 
longa,  690:  socialis,  770,  771*, 
773 

Gervilliopsis  ensiformis,  854 

Geyser,  water-and-gas,  607,  608* 

Geysers,  82,  265,  277,  291,  305*-309, 
307*,  308* ;  basins  of,  in  Yellow- 
stone Park,  152,  305,  306* ;  sili- 
ceous deposits  from :  geyserite, 
64§,  82§,  152,  305,  306,  307;  ter- 
races of  New  Zealand,  305* 

Giant  geyser,  307* 

Giantess  geyser,  307 

Giants'  Causeway,  261* 

Gibraltar,  131,  214 

— ,  Straits  of,  20  ;  currents  at,  49, 
229 

Gieseckite,  84§,  320,  453 

Gila  River,  885 

Gilbert  Islands,  36,  38,  39,  145 

DANA'S  MANUAL  —  67 


Ginkgo,  485 ;  adiantoides,  839 

Giordanella,  482 

Giraffe,  907 

Giraffidfe,  927 

Girvanella,  470,  502 ;  ocellata,  501* 

Givet  (Givetian)  limestone,  626 

Glabella,  420*,  421  § 

Glacial  period,  943  ;  American,  943 ; 
migration  of  species  caused  by, 
945 ;  elevation  of  the  land,  946 ; 
height  of  ice,  951 ;  slope  required 
for  flow,  952 ;  direction  of  flow, 
952,  955;  courses  of  scratches, 
953;  Driftless  area,  Wisconsin, 
953 ;  first  Retreat,  961 ;  final 
Retreat,  967  ;  moraine,  900,  963*  ; 
Kettle  moraine,  967 

—.foreign,  975,  995;  Asia,  977; 
Australia,  978;  Europe,  975, 
976* ;  New  Zealand,  South  Amer- 
ica, 978 

—  climate,  cause  of,  978  ;  supposed 
in  the  Triassic,  745 

— ,  map  of  N.  America  in,  after  page 
944 

—  conditions,  in  the  Permian,  698, 
737 

Glaciers,  195,  200,  233;  flow,  242; 
of  Zermatt,  237*  ;  cascades  con- 
nected with,  238 ;  lakes,  238,  240, 
251 

Glanzschiefer,  84 

Glass,  63§,  77,  86,  264,  265 ;  rela- 
tions of  glassy  rocks  to  stony, 
276,  289 

Glass  sponge,  57*,  72 
Glauber  salt,  137,  294 
Glauconite,  68§,  136§,  468,  822§,  823, 

824,  920 ;  see  also  Green  sand 
Glauconite  group  (beds),  815,  824, 

855 ;  marl,  865 

Glaucophane,  89,  318  ;  schist,  266 
Glaucophanyte,  89§ 
Gleditschia,  921 
Glen  Rose  beds,  817,  836 
Glimmerschiefer,  84 
Globigerina,  57,  134,  144,  433*,  855, 

935,  936  ;  rubra,  432* 
Globigerina  ooze,  144,  230,  433,  817 
Globostellate  spicule,  432* 
Globuliferous  rocks,  83 
Glossites,  621 

Glossoceras,  551 ;  desideratum,  573 
Glossopteris,  698,  699,  704 ;  Brown- 

iana,  698 

Glossopteris  Coal-measures,  698 
Glycimeris  reflexa,  917 
Glyphaaa,  760 

Glyptaster  occidentals,  551 
Glyptician,  790 
Glypticus  hieroglyphicus,  790 
Glyptocardia  speciosa,  612*,  620 
Glyptocrinus,    520 ;    decadactylus, 

511*,  514,  516 
Glyptodon,  1000,  1001,  1002;    cla- 

vipes,  1003* 
Glyptolepis,   417,    625,    626;    Que- 

becensis,  618* 
Glyptops  ornatus,  766*,  767 
Glyptostrobus      Europseus,      921; 

Grrenlandicus,  833 
Gnathodon  tenuides,  837 


Gneiss,  83§,  122,  447 

Gneissic  quartzyte,  82 

Gneissoid  granite,  83§,  227,  871 

Gnetaceae,  435 

Gnetum,  435 

Gobi,  Desert  of,  32,  33,  51 

Gorner  Glacier,  237*,  248 

Gornerhorn,  248 

Gold-bearing  veins,  338 ;  washings. 

170,  178 

Gold  Range,  739 
Gomphoceras,    549,    561,   568,   586, 

591,    599,   627;    angustum,    551; 

eos,  516 ;  oviforme,  602  ;  parvu- 

lum,  561* ;  Wabashense,  551 
Gomphonema  capitatum,  699  ;  gra- 

cile,  163, 164* 
Gomphotherium,  918 
Gondwana  Land,  737,  873-874,  937 

(period  of  existence) 

—  (Lower)  series,  698,  770 

—  (Upper)  series,  769 

Goniatite  limestone,  576,  598,  637, 

642,  647 
Goniatites,    570,    575,    586*    (first 

American),  593, 599, 700,  869 
Goniatites,  568,  599,  613,  614,  625, 

626,    642,    675,    686  ;    bicostatus, 

620  ;  complanatus,  .612,  620  ;  dis- 
coideus,  586,  602,  620;   intumes- 
cens,  614*,  620,  621,  627;  Lyoni, 
643*  ;  Marcellensis,  602  ;  mithrax, 
586*,  591  ;   Oweni,  643*  ;  Pater- 
soni,  614*,  620 ;  primordialis,  626  ; 
retrorsus,    626*,    627 ;    sinuosus, 
620 ;  Vanuxemi,  599* 

Goniobasis,  828,  829,  856 ;  convexa, 

856 

Gonioceras  anceps,  514 
Goniomya,  760 
Goniophora,    621 ;    Chemungensis, 

621  ;  perangulata,  601 
Goniopteris,  685 ;  arguta,  693 ;  ele- 

gans,  693,  705;  emarginata,  693, 

705 

Good-night  beds,  885 
Gordon-Bennett,    Mt.,    height    of, 

296 

Gorgonia,  55,  429*,  431§ 
Gorilla,  54 
Goro  Island,  150 
Gosiute  Range,  365 
Gothic  Mountain,  274,  275* 
Gotland  (Gothland),  Lower  Silurian 

in,  521  ;  Upper  Silurian,  564,  565, 

568,  569 
Grahamite,  662 
Grallae,  923 

Grammatophora  marina,  437*,  894* 
Grammoceras,  760 
Grammostomum  phyllodes,  432* 
Grammysia,    602,    621 ;    bisulcata, 

598*,   602,  626;    cingulata,  564*, 

567,  573 ;  communis,  621 ;  Ham- 

iltonensis,  602,  626 ;  subarcuata, 

620,  621 ;  triangulata,  573 
Grampian  group,  456 
Granatocrinus,  646 
Grand  Bank  of  Newfoundland,  88» 

—  Canon.    See  Colorado  Canon 

—  Chain,  732 

—  Gulf  group,  890,  891 


1058 


INDEX. 


Grand  Manan  Isl.,  subsidence  of,  350 

—  Portage  Bay,  469 
Granite,  82§-83,  122,  205,  259 

—  and  mica  schist,  448* 
Granitic    rocks,    78§ ;    sediments, 

744;  veins,  314,  326,  329*,  331, 

882*,  335,  386 

Granitoid  rocks,  77§,  85,  86,  87 
Granular   limestone,   79§ ;    quartz, 

82§ 
Granulyte,   83§    (kinds),   272,  316, 

325,  371 

Graphic  granulyte,  83§ 
Graphite,  62§,  79,  83,  313,  319,  485, 

714,  732;  in  Archaean,  453,  454, 

455,458 
Graphitic  coal,  657  ;  rocks,  79§,  83, 

449,  495,  518,  519,  658 
•Graptolites,  431§,  470§ ;  Cambrian, 

470,  474,  477*,  481  ;  Calciferous, 

497,  498*;    Lower  Silurian,  495, 

504,  505*,  510*,  515,  520,  522,  525, 

527,  718 ;  Upper  Silurian,  568, 574 ; 

Clinton,   545*;     Lower     Helder- 

berg,  560,  718 
Graptolithus     Clintonensis,     545*, 

550 
Graptolitic  shales  and   slates,  518, 

519,  520,  521,  568 
Grasses,  435,  945  ;  ash  of,  73,  75 
Grasshoppers,  419 
Grauliegende,  697 
Gravel,   75§,  76§ ;    auriferous,  344, 

810,  883,  887,  934 

Gravitation    theory    of    mountain- 
making,  381-383,  387 
Gray  band,  91,  542 

—  wacke,  80§,  408 

Great  Basin,  25,  119,  132,  195,  199, 
444,  635,  658,  735,  739,  746,  748, 
812,  818,  826,  882,  935 ;  faults  in, 


ranges.  365,  366*,  733,  789, 

811,  934,  935 
—  in  the  Quaternary,  988 

System,  366 

Great  Bear  Lake,  29,  200 

Great  Britain.     See  England 

Great  Lakes  of  North  America,  29, 
40,  199,  200,  201*,  442  ;  in  Quater- 
nary, 947,  948,  986 

Great  Northeast  Bay,  575,  683 

Great  Oolyte.     See  Oolyte 

Great  Salt  Lake,  25,  51,  120,  153, 
199,  200,  202,  362,  382,  444,  826, 
881,  882,  988  ;  valley,  361 

Great  Slave  Lake,  29 

Grecian  Archipelago,  296 

Greece,  Pikermi  beds  of,  927 

Green  earth,  68§ 

Green  Mts.,  24, 41,  326,  467,  490, 528, 
531,  536,  541,  945  (Arctic  plants) 

Green  Eiver  basin,  882,  893 

—  epoch  or  group,  365,  886,  901, 
918 

Green  sand.    See  Green  sand 

—  shale  of  the  Clinton,  542 

Greenland,  19,  40,  233,  234  (snow- 
line),  236,  239,  240,  249*,  251,  252, 
256,  272,  820,  337,  347,  376,  395  ; 
fiords,  240,  241,  948  ;  glaciers,  240, 
241*,  244,  251,  :941 ;  map  of 


western,  241*  ;  subsidence,  349, 
350 

Greenland,  Archaean  in,  444;  Car- 
bonic, 711 ;  Cretaceous,  794,  819, 
831,  833,  837,  838,  839,  840,  868, 
872  (climate),  873 ;  Tertiary,  819, 
921,  939  ;  Glacial,  945,  948 

Greensand,  68§,  136§,  191,  468,  477, 
820,  821,  822§,  824,  858,  887,  888. 
See  also  Glauconite 

Greenstone,  86, 449 

Greisen,  82,  83§ 

Grenville  limestone,  454,  493 

Grenzdolomit,  774 

Gres  Armoricain,  518 

—  bigarre,  769 

—  de  Fontainebleau,  205,  920 

—  des  Vosges,  769 
Gresslya  donaciformis,  791 
Greylock  (Mt.),  104,  495,  530* 
Gries  Glacier,  243 

Griffith  Isl.,  495 

Griffithides,  643,  676,  700;  Sanga- 
monensis,  691  ;  scitulus,  691 

Grindelwald  Glacier,  233,  238 

Grindstones,  80 

Grinnell  Land,  369,  606,  635,  663 

Grit,  80§ 

Grizzly  Bear,  950  (migration) 

Groovings.     See  Scratches 

Ground-ice,  232§ 

Ground-pines.     See  Lycopods 

Groups,  406§ 

Grus  proavus,  1002 

Gryllacris  lithanthraca,  704 

Gryphsea,  759,  779  (time  range),  792, 
834,  840,  860  ;  arcuata,  779,  790  ; 
bilobata,  790  ;  Bryani,  854  ;  cal- 
ceola,  760;  convexa,  854;  dila- 
tata,  779,  780*,  790,  819  (var. 
Tucumcari)  ;  forniculata,  836  ; 
incurva,  779* ;  mucronata,  817, 
887  ;  mutabilis,  854  ;  obliqua, 
790  ;  Pitcheri,  817,  835*,  836,  837, 
841*,  854  ;  sublobata,  790  ;  vesi- 
cularis,  841*,  854,  855,  866 ;  vir- 
gula,  791 

Gryphaea  beds,  790 ;  rock,  836 

Gryphaeostrea  vomer,  854 

Guadalupe  Mts.,  660 

Guanaco,  54 

Guano,  63§,  72§,  73,  153  (analysis), 
887 

Guatemala,  168 

Guelph  limestone,  543,  549,  551 

Guiana,  31 

Guinea,  33 

Gulf  of  Bothnia,  521 

—  of  California,  30,  51,  145,  200 

—  of  Carpentaria,  39 

—  of  Finland,  521 

—  of  Guinea,  295 

—  of  Mexico,  18,  20,  44,  45,  49,  190, 
191,  198,  217,  462,  483,  573.  794, 
814,  827,  834,  857,  881,  934 '(Ter- 
tiary), 940,  949 

—  ofPenjinsk,  927 

—  Stream,  44,  48, 49,  55,  56, 144, 166, 
229,  230,  256,  524  (Cambrian),  792, 
793,  872 

Gutenstein,  769,  774 
Guyot  Glacier,  238 


Gymnites  incultus,  774 

Gymnoptychus,  918 

Gymnosperms,  434§,  674,  718,  750 ; 
Neopaleozoic,  460 ;  Hamilton,  595, 
596;  Chemung,  610,612;  Subcar- 
boniferous,  639 ;  Carboniferous, 
666,  667,  672*,  673,  674,  689 

Gymnotoceras  rotelliforme,  757 

Gypidula  occidentalis,  602 

Gypsum,  69*§,  128,  138;  how 
formed,  554 ;  on  coral  islands, 
120 ;  in  the  Salina,  553,  554,  555* 

—  beds  of  Montinartre,  923 

Gyroceras,  591,  599,  642;  Burling- 
tonense,  642 ;  Jason,  591 ;  trans- 
versum,  602 ;  undulatum,  591 

Gyrodescrenatus,854;  petrosus,854 

Gyrodus,  417  ;  umbilicus,  417* 

Gyrolepis,  772 ;  tenuistriata,  774 

Haddock  bones,  analysis  of,  78 

Hade,  107§,  328§ 

Hadrosaurus,  846  ;  Foulkii,  845 

Haiti,  347,  891  &  985  (Miocene),  936 

Haleakala,  Mt.,  270,  277,  290,  291, 
346,  379  (density) 

Halemaumau,  269*,  271,  285,  291 

Halicalyptra  fimbriata,  433* 

Halisarcoids,  431§ 

Halitherium,  927 

Halloceras,  591 

Hallopus,  786 

Hallstadt  limestone,  774 

Halobia,  756,  757,  774  ;  dubia,  757  ; 
Lommeli,  757,  758,  792;  occiden- 
talis, 758 ;  ZitteH,  792 

Halobia  bed,  757 

Halodon  sculptus,  853* 

Halonia,  699;  pnlchella,  668*,  669, 
688 

Halysites,  310,  541,  547*,  551,  552, 
567,  568 ;  agglomeratus,  550 ; 
catenulatus,  514,  515,  516,  520, 522, 
544,  547*,  550,  551,  552,  567,  568, 
569;  escharoides,  550;  gracilis, 
510,  511*,  515 ;  interstinctus,  567 

Hamilton  period,  592 

Haminea  grandis,  916 

Hamites,  760.  867 :  alternatus,  865 ; 
attenuatus,  862*,  865;  elatior, 
867 :  Fremonti,  836 

Hanging  wall,  328§ 

Hannibal  shales,  637 

Haploceras,  760,  794 

Haploconus,  917 

Haplophlebium,  679 

Hard-pan,  128,  205§ 

Harding  sandstone,  495,  515 

Harlania  Halli,  545*,  549 

Harpes,  515,  520,  521,  551,  568,  625; 
antiquatus,  503 

Harpides,  521  ;  Atlanticus,  573 ; 
rugosus,  573 

Harpoceras,  794;  bifrons,  790; 
M'Clintocki,  792;  Murchisonse, 
790  ;  radians,  790  ;  serpentinum, 
790 

Harttia  Matthewi,  475* 

Harz  Mts.,  87,  563,  567,  569,  626, 
697,  734 

Hastings    sands  (and    clays),    858, 


INDEX. 


1059 


Hatchetigbee  beds,  888 

Hatteras.     See  Cape 

Hatteria,  54,  68T,  706,  798 

Hauynite,  88 

Hauptdolomit,  774 

Hauterivian,  859,  865 

Hawaii,   213,    282,    269*;    map  of, 

268*,  269,  270 
— ,  volcanic  action  on,  268*,  269*, 

372,  379 
Hawaiian    Islands,  36*  (map),  51, 

145,  150,  163,  324,  350,  392 
Hawkesbury  sandstone,  698,  770 
Hawthorn  beds,  891 
Haystack  Mt.,  937 
Headon  beds  (series),  926 
Heard  Island,  241,  242 
Heat,  253;    earth's   interior,   257; 

from     chemical     and     physical 

changes  and    mechanical  action, 

258 ;    from    crushing,    322,    326 ; 

from  interior  sources,  effects  of, 

260,  381 ;  in  mines,  339 
Heath,  945 
Heavy  spar,  69§ 
Hebrides,  218;    Archaean   in,  456, 

867 

Hecla  mine,  339 
Hecla  Mt.,  241,  286,  305 
Hedgehog,  54,  427,  930 
Helaletes,  907,  918 
Helderberg  Mts.,  543,  553,  555,  561, 

579 

Helderberg,  Lower,  558 
— ,  Upper,  579 
Helena  Canon,  515 
Helicina    occulta,   966;   orbiculata, 

966 ;  profuuda,  966 
Helicoceras,    861 ;    Mortoni,    855 ; 

Navarroense,  855 
Helicopsyche,  60 
Helicotoma,  516 ;    planulata,  507*, 

514 
Heliolites,  521,  550,  552,  567;  inter- 

stinctus,     520,     522,     550,    568; 

porosus,    626,    628;    pyriformis, 

550,  568 ;  spiniporus,  547*,  550 
Heliophyllum,  581,  611 ;  confluens, 

601;    Halli,   590,  597*,   bOl,   611, 

625 ;  obconicum,  601 
Heliosphsera,  319 
Heliscomys,  918 
Helix,   425*;    Cuperi,   966;    fulva, 

966;    labyrinthica,  926;    lineata, 

966 ;  occlusa,  926 ;  pulchella,  966  ; 

striatella,  966 ;  Turonensis,  926 
Helix  family,  690 
Hell  Gate,  211 
Helminths,  423 
Helodus,  644,  702 
Helohyus,  918 
Helvetian  group,  926 
Hemapedina,  779 
Hematite,  70§,  71,  83,  123,  126,  127, 

449,  450,  453,  539,  665 
Hemeras,  407§ 
Hemeristia  occidentalis,  691 
Hemiaspis  limuloides,    565*;    spe- 

rata,  567 
Hemiaster,    834,    840;    parastatus, 

854;  Eegulusanus,  866;  Texanus, 

855 ;  Verneuili,  866 


Hemicidaris,  779 ;  intermedia,  790 ; 

Purbeckensis,  791 
Hemicystites,  516 
Hemipristis  serra,  917 
Hemipronites    punctuliferus,    562 ; 

radiatus,  562 
Hemipsalodon,  918 
Heinipteroids,  Carboniferous,  691, 

702 ;  Paleozoic,  721,  722 
Hemipters,  419,  520,  525,  574,  756, 

900 

Hemitrochiscus  paradoxus,  707 
Hemitrypa,  579 
Hempstead  beds,  926 
Henry  Mts.,  301,  876 
Hepatic*,  434,  436 
Heptodon,  918 

Herbivores,  902,  929,  930,  981 
Herculaneum,  280 
Hercynian  beds,  564;  fauna,  Kay- 

ser's,    569;    Question,   Clarke's, 

569-570 

Hercynian  system,  Bertrand's,  734 
Herring,  862,  879,  901 
Hervey  Islands,  36,  37,  350 
Hesperomys,  919 
Hesperornis,  852,  864,  871 ;  regalis, 

850*,  852 

Heteraster  oblongus,  865 
Heteroborus,  925 
Heteroceras,  855 
Heterocercal,  401,  402,  416§ 
Heterocrinus,  516, 532;  Canadensis, 

514,  516 ;  geniculatus,  516 
Heteromyaries,  525 
Heteropods,  506 
Heteroschisma,  601 
Hettangiau,  774,  790 
Hexacoralla,  777§,  860 
Hexactinellids,  57,  431§,  432*,  497, 

498*,  504,  611,  639,  646,  777*,  860 
Hexameroceras  delphicolum,  551 
Hexaprotodon,  927 
Highland  Range,  443,  469 
Highlands  of  N.  J.  and  of  Putnam 

Co.,  N.T.,  24,  443,  530,  531,  745 
Highwood  Mts.,  876 
Hilo,  295 

Hils  formation,  865 
Himalayas,  26,  32,  41,  234,  365,  379, 

392 
—  Archaean  in,  456 ;  Silurian,  521 ; 

Jurassic,  776,  791 ;  Tertiary,  347, 

365,  892,  920 ;  changes  of  level  in, 

932,   933,  936,  938;    Quaternary, 

392,  936;    glaciers  in,  239,  240; 

upturning  and  elevation  of,  368*, 

936 
Himantidium     arcus,     163,     164*; 

Monodon,  163,  164* 
Hindeastrsea  discoidea,  840* 
Hindia,  562,  584,  590 
Hindostan,  22 
Hindu-Kush,  32,  41 
Hipparion,  919,  927 
Hipparionyx,  578 ;  proximus,  579 
Hippidium,  919,  1002 
Hippopodium  ponderosum,  790 
Hippopotamus,   54,  906,  925,  927, 

928,  930  ;  major,  927,  1004,  1006  ; 

Pentlandi,  1006 
Hippotherium,  927 ;  ingenuum,  1001 


Hippurite  limestone,  836,  859,  866 

Hippurites,  866,  877  (end) ;  brevis, 
866;  Corbaricus,  866;  dilatatus, 
861*,  866;  floridus,  866;  gigan- 
teus,  866 ;  organisans,  867  ;  Petro- 
corriensis%866;  socialis,  866 ;  Tou- 
casi,  866 ;  Toucasianus,  861* 

Hoang  Ho,  30,  195,  196*,  198 

Hoei  Ho,  198 

Hog,  906,  910,  911,  930  ;  family,  909, 
924,  928,  930 

Holaspis,  625 

Holaster,  840,  860;  Isevis,  866; 
nodulosus,  865  ;  planus,  866  ;  sim- 
plex, 837 ;  subglobosus,  866 ;  sub- 
orbicularis,  866 

Holectypus  planatus,  837 

Holometopus  Angelini,  573;  lim- 
batus,  573 

Holonema,  617  ;  rugosum,  616*,  618, 
621 

Holopea,  499*,  514,  521,  562;  an- 
tiqua,  558  ;  dilucula,  499*  ;  elon- 
gata,  558  ;  subconica,  558 ;  Sweeti, 
478*  ;  turgida,  501 

Holopella,  520;  conica,  567;  gre- 
garia,  567 ;  obsoleta,  567 

Holops  pneumaticus,  848 

Holoptychius,  417,  510,  618*,  619, 
625*,  626,  702  ;  Americanus,  621 ; 
filosus,  621 ;  giganteus,  621 ;  hor- 
ridus,  621 ;  nobilissimus,  627 ; 
rugosus,  621 

Holothurians,  423 

Holothurioids,  427§ 

Holy  Cross  Mt.,  250 

Holy  Island,  156 

Holyoke  Mt.,  802,  803 

Homacanthus  gracilis,  591 

Homacodon,  918  ;  priscus,  906 

Homalonotus,  422§,  520,  521,  546, 
562,  570,  578,  579,  586,  591,  599, 
626;  Dawsoni,  562;  delphino- 
cephalus,  549*  550,  551,  567,  569 ; 
Knightii,  567,  573;  major,  578; 
Vanuxemi,  570 

Homewood  sandstone,  656 

Homo  diluvii  testis,  921 

Homocercal  tails  of  fishes,  417 

Homocrinus,  562 

Homotaxial,  398 

Ho-Nan,  198 

Honduras,  20,  747,  756 

Honesdale  sandstone,  606 

Hood  Mt.,  height  of,  296 ;  glaciers 
of,  240,  945 

Hoogly,  mouth  of  the  Ganges,  212 

Hoplites  auritus,  865 ;  Deluci,  865 ; 
Deshayesi,  887,  854,  864 ;  Desori, 
867 ;  dispar,  867 ;  interruptus,  865 ; 
lautus,  865;  Noricus,  865;  radia- 
tus, 865 ;  splendens,  865 

Hoplolichas,  591 

Hoplophoneus,  918 

Hoplophorus,  1003 

Horizonality  of  strata,  98 

Horn-silver,  840 

Hornblende,  66,  67§* 

—  andesyte,  86§,  892;  granite,  82, 
88§,  85§ ;  picryte,  88§ 

—.pyroxene,  and  chrysolite  rocks, 


1060 


INDEX. 


Hornblende  schist,  85§ 
Hornblendyte,  88§,  325,  532 
Hornstonel  82,  540,  579§,  580,  584, 

646,    859;    in    Corniferous,   with 

Protophytes,  582,  583* 
Horse,   54,  55,  907,  908,  911,  912, 

914*,  927 

—  type,  evolution  of,  912,  913*,  929, 
931 

Horse  in  a  vein,  330§ 

Horse-shoe  crab,  420 

Horse-tail.     See  Equiseta 

Horsetown  beds,  815,  818,  820,  831, 
837 

Horton  series,  639 

Hosselkus  limestone,  757 

Hot  springs,  121,  135,  137,  152,  265, 
277,  305,  306,  313,  320,  323,  343 ; 
analyses  of  waters,  121 ;  life  of, 
60,  152,  308,  454 ;  superficial  vein- 
making  at,  334 

Housatonic  River,  227*,  325 

House  Range,  Utah,  494 

Hualalai  Mt.,  268*,  269 

Huamampampa  sandstone,  628 

Hudson  Bay,  29,  40,  442,  541,  552, 
883,  947,  948,  949 

Hudson  -  Champlain  trough,  537, 
572 

Hudson  epoch,  510 

—  River,   212,   216,   528,   529*,  530, 
537,  540,  541,  558,  579,  628,  734, 
743,  744,  745;   submarine  chan- 
nel,   18*,  745,  949;    valley,  357, 
552,  558,  559,  579,  605,  982 

Huerfano  group,  893 
Human  bones,  analysis  of,  73 
Humboldt    Glacier,    241;    Ranges, 

365,  733,   811,   812,  945;  region, 

746,  757,  760 
Humite,  67§ 
Humming  birds,  54,  55 
Humus    acids,  119,  122,  124§,  125, 

128,  129,  139 
Hunan,  696 
Hungary,  Archaean  in,  455 ;  Upper 

Silurian,  573  ;  Tertiary,  938 
Hung-tse  Lake,  198 
Huron,   Lake,  200,  201*,  445,  449, 

452,  493,  533,  540,  542,  552,  553, 

572,  592.  635,  947 
Huron      Cupriferous     Formation, 

445 

—  River,  947 

—  shale,  606 

Huron  ia,  549  ;  Bigsbyi,  551 ;  verte- 

bralis,  551 
Huronian,  407,  445,  446,  447,  448, 

449,  450,  451,  453,   454,  458,  466, 

468,  488 

Hurricane  fault,  363*,  747 
Hyaena,  927  ;  crocuta,  1004 ;  spelaea, 

1004,  1006,  1009 
Hyaenarctos,  927 
Hyaenocyon,  918 
Hyaenodictis,  925 
Hyaenodon,  918,  926 ;  dasynroides, 

924 ;  leptorhynchus,  926 
Hyalina  arborea,  966 
Hyalomicte,  83§ 
Hyattella  congests,  546*,  550 
Hybocrinus,  514 


Hybodonts,  415§,  416*,   643,  644*, 

647,  772 
Hybodus,   772  (first),  783;  minor, 

416*,  772  ;  plicatilis,  416*,  772,  774 
Hydnoceras,  646 
Hydra,  429*,  430 
Hydration,  128 
Hydraulic  cement,    79§,    80,    555; 

limestone,  79§,  555,  592 
Hydrocarbon,  62,  74,  124 
Hydrocephalus,  482 
Hydrochloric  acid,   68,  278;    from 

volcanoes,  278,  294 
Hydrogen,  61,  62  ;  from  volcanoes, 

278,  287,  293,  294 

—  sulphide,  119,  124,  125,  523,  554 
Hydroids,  140,  419,  430§,  547*,  560 
Hydromica,  65§,  83,  318 ;  granite, 

82  ;  quartzyte,  82  ;  schist,  80,  82, 

84§ 

Hydrotalcite,  453 
Hydrozoans,    140,   418,   419,    429*, 

430*§,  431 
Hyena,  54 

Hylajosaurus  Oweni,  863 
Hylerpeton,  682 
Hylonomus,  682,  706 
Hymenocarids,    Upper    Cambrian, 

488 

Hymenocaris  vermicauda,  481* 
Hymenophyllites,   645,   689;  Gers- 

dorffi,  622 ;  Hildrethi,  670*,  689  ; 

obtusilobus,  622 ;  spinosus,  689 
Hymenopters,   419,    679,   783,   794, 

900  (number  of  Florissant) 
Hyodectes,  925 

Hyolithellus,  471,  472  ;  micans,  472* 
Hyolithes,   447,   471,  478,  481,  482, 

514,  562,  599,  621 ;  Acadicus,  475*  ; 

Americanus,  471, 472* ;  Danianus, 

475* ;    gregarius,    478* ;     impar, 

472*  ;  levigatus,  482 ;  ligea,   590  ; 

princeps,  472* 
Hyomeryx,  918 

Hyopotamus,  918 ;  bovinus,  926 
Hyopsodus,  918 
Hyperodapedon,  772 
Hypersthene,  67§,  86,  87,  88 
Hypertragulus,  918 
Hyperyte,  87§ 
Hypisodus,  918 
Hypnum,  154 

Hypogeic  work,  118§,  345-896 
Hypogene  rocks,  311§ 
Hyposaurus  Rogersi,  848;  Webbii, 

*848 

Hypostome,  421  § 
Hypsilophodon  Foxi,  863 
Hyrachus,  907 
Hyrachyus,  918,  923 
Hyracodon,  910,  918 ;  Nebrascensis, 

910* 

Hyracops,  917 

Hyracotherium,  913*,  918,  923,  925 
Hyrax,  54,  55 
Hystricops,  919 
Hystrix,  927 

Ibis,  928 

Ice  (see  also  Glaciers  ;  Water, 
freezing),  231,  282;  glacier,  243, 
846  ;  plasticity,  243,  244,  245 


I  Ice,  effects  on  lakes,  rivers,  and  sea- 
coasts,  232  ;  fractures  from  tor- 
sion, 371,  372* 

Iceberg  theory  of  the  drift,  942 

Icebergs,  241,  251-252;  transporta- 
tion by,  217,  230,  252  ;  transported 
by  the  Labrador  current,  229,  239 

Iceland,  19,  48,  256,  286,  297  ;  gey- 
sers, 82,  305,  307 ;  Sequoia  of,  939  ; 
volcanoes  of,  297 

Ichthyocrinus  Isevis,  547*,  550 

Ichthyodectes,  862 

Ichthyopterygians,  760 

Ichthyornis  dispar,  851*  ;  victor, 
851*,  852 

Ichthyosarcolithus  anguis,  836 ; 
crassifibra,  836  ;  planatus,  836 

Ichthyosaurs,  792,  797 ;  Jurassic, 
760,  761,  790  ;  number  of  British, 
784 ;  Triassic,  774 

Ichthyosaurus,  749,  773,  790 ;  corn- 
munis,  784*  ;  Nordenskioldi,  792 ; 
polaris,  792 

Icla  shales,  628 

Ictops,  918 

Idaho,  23  (height);  Cambrian  in, 
477  ;  Calciferous,  501 ;  Subcarbon- 
iferous,  639,  647;  Triassic,  746, 
747,  757  ;  Jurassic,  747,  760 ;  Ter- 
tiary, 938 

Idocrase,  66§,  313 

Idonearca  vulgaris,  854 

Igaliko,  Firth  of,  350 

Igneous  action  and  its  results,  265 ; 
exterior  agencies,  265 ;  volcanoes, 
267;  non-volcanic  eruptions,  297  ; 
thermal  waters,  geysers,  305 

—  ejections  and  intrusions,  89,  258, 
364,    882,    383,    658,    811  ;    great 
in    the    later   part  of  geological 
time,    392,    441  ;    surficial,    299, 
300*  ;  veins  made  by,  338-343 

—  fusion,  source  of,  804 

—  phenomena     due     to     exterior 
agencies,  265,  266 

—  rocks,  67,  76§,  80,  272-274 

—  and  metam orphic,  relations  of, 
326-327 

Iguana,  863 

Iguanavus  teres,  849 

Iguanodon,  786,  828,  845,  856,  863, 
865  ;  Bernissartensis,  863*  ;  Man- 
telli,  863* 

Ilex,  854 ;  cassine,  74,  75 

Ilfracombe  group,  625 

IlLenus,  500,  502,  508,  520,  521,  546, 
551,  568  ;  Arcturus,  503  ;  Bay- 
fieldi,  503  ;  Bowmani,  520  ;  cras- 
sicauda,  515  ;  Davisi,  519*  ; 
globosus,  503  ;  loxus,  549,  551 ; 
Taurus,  515  ;  Thomsoni,  567 

Illawarra,  261* 

Illicium,  896 

Illinois,  mean  height  of,  28 ;  up- 
lifts in,  732 ;  lead  mines,  842,  522 

Illinois  River,  948 

Ilmen  Mts.,  85 

Ilmenite,  70§,  87 

Ilyanassa  obsoleta,  994 

Ilyodes,  691 

India,  32,  34,  160,  299,  846,  406; 
united  with  S.  Africa,  871,  873,  893 


INDEX. 


1061 


India,  Archaean  in,  466  ;  Cambrian, 
483  ;  Upper  Silurian,  564 ;  Car- 
boniferous, 632,  693  ;  Permian, 
686,  698,  699,  737,  770  ;  Triassic, 
632,  698,  737,  769,  770,  773,  791 ; 
Jurassic,  698,  776,  791,  873;  Cre- 
taceous, 299,  833,  857,  866,  867, 
873,  874,  876;  Tertiary,  299,  920, 
923,  925,  927,  936,  938 

Indian  Ocean,  17,  19,  23,  31,  33,  43, 
44,  50,  296,  297,  632,  937,  939  ;  top- 
ographic changes  in,  737 

Indian  Territory,  Cretaceous  in,  817, 
836 

Indiana,  23  (height),  207,  357 ;  min- 
eral gas  and  oil  in,  206,  522,  523, 
607 ;  yield,  523 

Indianaite,  638§ 

Individualities  in  nature,  9 

Indrodon,  917 

Indus  Basin,  alluvial  cones  of,  195* 

—  delta,  earthquakes  of  1819   and 
1845,  349 

— ,  valley  of  Upper,  368 

Infra-Cretace,  865 

Infra-Lias,  774 

Infusorial  earth,  81  §,  895;  Tertiary, 
894*,  895 

Ink-bag  of  Belemnite,  782* 

Inocaulis  arbuscula,  516 

Inoceramus,  759,  760,  834,  837,  840, 
860,  867,  877  (end) ;  biformis,  855 ; 
concentricus,  865;  confertim-an- 
nulatus,  854;  Crispii,  855,  867; 
Crispii  var.  Barabini,  854;  de- 
formis,  855;  digitatus,  866;  di- 
midius,  841*;  exogyroides,  855; 
fragilis,  855;  labiatus,  840,  841*, 
854,  855,  866;  latus,  854,  867; 
raytiloides,  867 ;  problematicus, 
(=  I.  labiatus),  841* ;  proximus, 
854 ;  striatus,  866 ;  sublsevis,  855 ; 
subquadratus,  855 ;  substriatus, 
790 ;  sulcatus,  865 ;  tenuicostatus, 
855 ;  tenuilineatus,  855 ;  umbona- 
tus,  855 

Inoperculates,  54 

Inorganic  distinguished  from  or- 
ganic, 9,  413 

Insectivores,  54,  768,  902,  903,  906, 
907,  911,  918,  925,  927,  928,  929, 930 

Insects,  54,  72,  141,  154.  158,  163, 
189,  418,  419§,  520;  derivation, 
723-724  ;  relations  to  other  articu- 
lates, 724  ;  tracks,  95,  742  ;  Lower 
Silurian,  496,  521,  525;  Upper  Si- 
lurian, 574,  721  (first) ;  Devonian, 
575,  600*,  601;  Subcarboniferous 
(none),  643;  Carboniferous,  657, 
674,  677,  679*,  691,  692,  701*,  704; 
Permian,  686 ;  Paleozoic,  525, 721, 
727  ;  post-Paleozoic,  736 ;  Triassic, 
742,  750*,  751,  756,  757,  771,  794 ; 
Jurassic,  775,  776,  783*,  791,  794 ; 
Tertiary,  202,  887,  893,  900*,  901, 
921,  922,  923  ;  Glacial,  946 

Integripallial,  425§ 

Interior  Continental  region,  34, 199 

—  of  N.  Amer.,  348,  387,  580,  581, 
590,   592,   593-594,  606,  714,  715, 
716,  856,  944  ;  of  Europe,  533,  573, 
627,  693,  769,  775,  867 


Interior  plains,  24§ 

Intestinal  worms,  423 

Invertebrates,  404,  414,  418;  rela- 
tion of,  to  Vertebrates,  418; 
reign  of,  460 

locrinus,  516 ;  crassus,  514 

Iodine,  331,  835 

lolitic  granite,  83 

lone  formation,  892 

Iowa,  height  of,  23  ;  uplifts  in,  782  ; 
lead  mines,  342,  522 

Iowa-Texas  Coal-measure  region, 
648 

Iphidea  bella,  471* 

Ireland,  203;  disturbances,  534; 
eruptions,  258,  518;  peat-beds, 
154 

— ,  Archsean  in,  456 ;  Cambrian,  480, 
481, 482,  534 ;  Lower  Silurian,  518, 
534;  Upper  Silurian,  563,  574; 
Devonian,  622,  626 ;  Subcarbonif- 
erous, 694,  695 ;  Carboniferous, 
693,  704;  Permian,  697;  Creta- 
ceous, 856 ;  Tertiary,  938 

Irish  Deer,  927 

Iron,  density  of,  15;  oxidation  of, 
123;  carbonate,  81,  125;  oxides, 
62,  124 ;  sulphate,  70 ;  sulphides, 
70,  80,  123 

—  age,  445 

—  ore  (and  ore  beds),  69, 70,  92, 127, 
315,  326,  327,  344,  391 ;  Archaean, 
376,  445,  446,  449*,  450,  451,  453, 
454, 455,  456,  458 ;  Cambrian,  446  ; 
Lower  Silurian,  524 ;  Clinton,  539, 
542,  543,  572,  728 ;  Carboniferous, 
650,  651,   652,   656,  663,    664-665, 
708 ;  Jurassic,  792 

—  sandstone,  542 
Iron  Mts.,  444,  449 
Ironstone,  344,  688 

Irrawaddy,  ratio  of  sediment  to 
water,  190 

Isastrsea,  777,  778  (number  of  Brit- 
ish) ;  discoidea,  854 ;  explanata, 
790  ;  Murchisoni,  790 ;  oblonga, 
777* 

Ischadites,  562 ;  bursiformis,  590 

Ischyromys,  918 

Ischyrosaurus,  856 ;  antiquus,  829, 
856 

Isectolophus,  918 

Isis  nobilis,  72§ 

Island  Range  of  British  Columbia, 
739,  747,  809 

Islands,  chains  of,  20,  374 ;  curves 
in,  35*,  36*,  37*,  39* 

—  as  parts  of  continents,  22 ;    of 
British  Columbia,  390 

Isle  of  Wight.    See  Wight 

Isle  Royale,  483 

Isocardia    Conradi,    854;    fraterna, 

917 ;  medialis,  836  ;  Washita,  837 
Isocrymal  chart,  46§,  47* 
Isopods,  420*,  421§,  422,  438,  439§, 

487,  512,  623,  624,  720,  723,  783 
Isoseismic  curves,  375 
Isostasy,  377§,  378,  379,  382,  875 
Isotelus  canalis,  503 ;    platycepha- 

lus,  508* 

Isothermal  chart,  46§,  47* 
Itabyryte,  83§ 


Itacolumyte,  82 

Italy,  296  (volcanoes) ;  Subcarbon- 

iferous    in,    693 ;    Carboniferous, 

693 ;  Triassic,  768  ;  Jurassic,  793 ; 

Oolyte,    309;     Cretaceous,    857. 

859  ;  Tertiary,  921,  926,  927,  938 

(eruptions) 
Ithaca  group,  603,  604,  605,  614,  620, 

629 

Ithygrammodon,  918 
lulids,  419 
lulus,  676 
Ixtaccituatl,  Mt.,  height  of,  937 

Jackson  coal,  657 

—  epoch,  884,  889,  907,  916 

Jakobshavn  Glacier,  244 

Jamaica,  29,  163,  347,  891,  935, 
936 

James  River,  816 

Jan  Mayen,  19,  297 

Janassa  bituminosa,  707 

Janira  occidentals,  836;  Wrightii, 
837 

Japan,  19,  22,  32,  40,  183,  277,  280, 
290,  293,  296,  297  ;  earthquakes  of, 
373,  374 ;  Carboniferous,  696, 700 ; 
Tertiary,  920 

Japan  Sea,  927 

Jasper,  82§,  84,  309,  450,  453,  454 

Java,  38,  40,  277,  297  (volcanoes), 
920 

Jeanpaullia  Munsteriana,  756;  ra- 
diata,  756 

Jeff  Davis  Peak,  945 

Jefferson  Mt.,  240  (glacier),  296 

Jelly-fish,  430§ 

Jet,  775§ 

Joaquin  River,  30 

Jock  coal-bed,  656 

Joggins  Coal-measures,  654*  (sec- 
tion), 658,  682,  690 

John  Day  beds,  884,  886,  894,  911, 
.  918,  926 

John  Day  River,  886,  894 

Johnstown  cement-bed,  652 

Joints,  111§,  112*,  371-572,  598 

Jokuls  Fiord,  reconstructed  glacier, 
242 

Joliet  building-stone,  541 

Jolleytown  coal-bed,  651 

Joplin  lead  mines,  522 

Jordan  valley,  23 

Jorullo  (Mt.),  27 

Judith  River  beds,  828,  829,  847, 
850,856 

Juglans,  921 ;  denticulata,  889 ; 
rhamnoides,  839  ;  rugosa,  889 

Jukes  Butte,  301* 

Juncus,  75 

Jungfrau,  236,  237 

Jupiter,  density  of,  16 ;  oblique  lines 
on,  395 

Jupiter  Serapis,  349 

Jura  limestone,  738 

Jura  Mts.,  207,  382;  Triassic  in, 
768 ;  Jurassic,  738,  774,  798 ;  Cre- 
taceous, 859 ;  Tertiary  mountain- 
making,  367,  368*  (section),  919, 
932 

Jura-Trias,  738,  749,  770,  881 ;  of 
Elk  Mts.,  864* 


1062 


INDEX. 


Jurassic  period,  738,  739,  758,  774, 

857,  873  ;  foreign,  774 
Justedal  Glacier,  251 
Juvavites,  757 

Kaibab  fault  and  fold,  362,  868* 

Kainozoic.    See  Cenozoic 

Kalium,  61 

Kamchatka,  40 ;  volcanoes  of,  296 

Kames,  970 

Kampecaris  Forfarensis,  625 

Kanab  Canon,  581 

Kanawha  Salines,  689 

Kangaroo,  415 

Kansas,  23  (height),  842  (lead 
mines) ;  Paleozoic  in,  342  ;  Car- 
boniferous, 130,  665,  674,  678,  690, 
691  ;  Permian,  660 ;  Cretaceous, 
813,  817,  819,  826,  829,  843,  848, 
849,  850,  851,  852,  864,  872,  873 ; 
Tertiary,  885 

Kaolin  (kaolinite),  68§,  81§,  134,  295 

Karharbari  Coal-measures,  698 

Karoo  beds,  698,  699,  737,  770,  778 

Kashmir,  32,  770 

Kaskaskia  group,  634,  637,  646 

Kauai,  36,  283,  290 

Kea,  Mt.,  27,  179,  268*,  269,  270, 
276,  290,  291 ;  density  of,  379 

Keeling  atoll,  20 

Keewatin,  466 

Kellaway  beds,  777 

Kellaways  rock,  775,  790 

Kelp,  155 

Kenia,  or  Kenya,  Mt.,  88,  977 

Kennedy  Channel,  495,  559 

Kenodiscus  Schmidti,  773 

Kent  Belt  of  limestone,  529*,  580 

Kent-Cornwall  ridge,  Conn.,  449, 
531 

Kentucky,  23  (height),  387;  cav- 
erns, 130  (length),  137,  207  ;  min- 
eral oil,  609;  Cincinnati  beds, 
504,  692;  Cincinnati  uplift  of, 
387,  490,  532 

Kentucky  River,  503 

Keokuk  group,  634,  637  ;  limestone, 
97,  138,  342,  638,  644,  646,  647 

Kerguelen  Land,  296  (volcanoes) 

Kermadec  Islands,  37 

Kersantyte,  86§ 

Kettle  holes,  970,  992,  993* 

Keuper,  Keuperian,  411,  788,  769, 
771,  772,  773,  774 

— ,  Lower,  755,  771 

Keupermergel,  769,  774 

Keweenaw,  Keweenawan,  Kewee- 
nawian,  Keweenian,  447,  464 

—  copper  region,  341,  342,  466,  468, 
483 

—  group,  445,  447,  465, 468,  469, 488, 
484 

—  Point,  465 
Key  West,  168 
Khingan  Mts..  82 

Kiama,  281 ;  basaltic  columns,  261*, 
262*  ;  dike  with  outflow,  262* 

Kiamitia  clays,  817 

Kicking  Horse  Pass,  26,  469,  495 

Kilauea,  178,  268*,  269*,  270,  271, 
272,  276,  277-283  (passim),  284*, 
285*,  286*,  288,  291,  293,  295,  308 


Kilima-Njaro,  Mt.,  83;   height  of, 

296 

Killinite,  821 
Kimberley  shale,  770 
Kimmeridge  clay,  411,  775 
Kimmeridgian  group,  775,  776,  779, 

780,  790 
Kinderhook  group,   634,   687,   638, 

646,  647,  709 
King  William's  Island,  495,  524,  544, 

552 

Kingdoms  of  nature,  9 
Kingfisher,  54,  852 
Kingsmill    Islands.      See    Gilbert 

Islands 
Kionoceras  laqueatum,  500*  ;  strix, 

551 
Kittanning  coal-beds,  652,  663,  664, 

688 

—  Mts.,  538,  539  ;  valley,  857 
Kiusiu  Island,  277 
Klamath  Mts.,  659,  747,  809 
Knobstone  group,  637,  638 
Knorria,  610,  639,  645,  689,  698,  699  ; 

acicularis,  626,  699,  704;  imbri- 
cata,  645,  689,  699,  704 

Knox  dolomyte,  468,  493 ;  sand- 
stone, 468 

Knoxville  beds,  760,  815,  818,  820, 
831,  837 

Kossen  beds.  769,  774 

Kohala  Range,  Hawaii,  269 

Kohlenkeuper,  769 

Koipato  group,  747 

Koko  Head,  Oahu,  271* 

Kome  group  (beds),  819,  883, 
888 

Kong  Mts.,  33 

Kootanie  beds  (group),  815,  818, 
819,  820,  833,  834,  868,  872 

—  Pass,  818 

Kotzebue  Sound,  240,  640,  1003 

Krakatoa  volcano,  163,  291 

Kuen-Lun  Mts.,  26,  82 

Kuhn  Islands,  776 

Kupferschiefer,  697,  707 

Kurile  Islands,  19,  296  (volcanoes), 

297 
Kutorgina,  480,  481,  486 ;  cingulata, 

471*,  480,  573 ;  Labradorica  var. 

Swantonensis,  480 
Kyanite.     See  Cyanite 

Labradioryte,  86§,  825 

ihyric,  77§ 

'ador,  350,  442,  944  (precipita- 
;ion),  948  (fiords)  ;  Cambrian  in, 
467 

current,  45,  48,  55,  166,  229,  230, 
i,  873 

LaWdorian,  446 

LabiWite,  64§,  65,  77,  85,  86,  87, 
88,  273^295,  311,  318,  319,  320,  328, 
324,  325,  442 

Labrosaurus,  766 

Labyrinthine  structure  of  teeth, 
417*,  725 

Labyrinthodonts,  417*§,  796 ;  Coal- 
measure,  772 ;  Permian,  869 ;  Tri- 
assic,  772*,  869  ;  Cretaceous,  870 

Laccadive  Islands,  145 

Laccolite,  301§ 


Laccoliths,  296,  301*,  802,  803,  845, 
383,  469,  804,  806,  807,  876 

Lacerta,  787 

Lacertians,  787,  848 

Lacustrine  areas,  Tertiary,  202, 365, 
882 

—  beds    (deposits),    76,    191,    202; 
Quaternary,  985,  986,  988 

—  limestone  of  Beauce,  926 
Ladrones,  19,  20,  37 ;  volcanoes  of, 

296 
Laelaps  aquilunguis,  847  ;  incrassa- 

tus,  847  . 

Laevibuccinum  lineatum,  915 
Lafayette    beds  (group),   888,  890, 

892 

—  formation,  964 
Lagomys  spelsetus,  1006 
Lagrange  group,  885,  891,  896 
Lahontan  region,  119, 133 
Lake  Agassiz,  985 

—  Bonneville,  988 

—  Cham  plain,  982 

—  Lahontan,  988 

—  of  the  Woods,  200,  446 

—  Warren,  987 

Lakes,  Great,  elevated  shore  lines 
of,  986.  See  Great  Lakes 

Lakes,  166,  198,  201* 

Lambdotherium,  918 

Lamellibranchs,  424§,  425*§ 

Laminarians,  56 

Laminated  rocks,  80§,  309;  struc- 
ture, 92§ 

Lamna,  144,  863;  compressa,  855; 
elegans,  416*,  901*,  925,  926; 
Texana,  843*,  855 

Lampreys,  418§ 

Land,  arrangement  of,  16,  21 ;  be 
low  sea  level,  22,  23 ;  in  one  hem 
isphere,  16* ;  mean  height  of,  23 ; 
ratio  of,  to  water,  16 

Land-shells,  54 

Landenian  group,  925 

Land's  End,  317  - 

Landslides,  208,  232 

Langhian  group,  926 

Lanthanum,  449 

Laodon  venustus,  767* 

Laopithecus,  918 

Laopteryx,  768 ;  priscus,  768 

Laosaurus  censors,  765* 

Lapilli,  267 

Lapland,  234  (snow-line) ;  Archaean 
in,  456 ;  Cambrian,  484 

La  Plata  (Rio  de  la  Plata),  24,  80, 
171,  191  (ratio  of  sediment  to 
water) ;  Cretaceous  of,  867 

Laramide  Range,  382,  383,  389,  891, 
483,  572,  581 ;  Mountain  System, 
359*-364,  375,  380,  383,  398,  391, 
406,  874*-876,  882,  883 

Laramie  beds,  824,  826,  827,  828, 
846,  847,  850,  852,  856,  870,  873, 
880,  893 

—  (Upper),  815,  821,  825,  827,  828, 
829,  830,  856,  873,  875 

—  Mts.,  748 

—  Plains,  747 

Lasiograptus  mucronatus,  510* 
Lassens  Peak,  87,  296,  749,  987 
Laumontite,  68 


INDEX. 


1063 


Laurentian,  445 

— ,  the  Champlain  period,  941 

Laurentide  Mts.,  445 

Laurus,   837,    840,    854,    921,    922; 

socialis,  839 

Lauteraar  Glacier,  237,  248 
Lauzon  group,  496 
Lava,  76,  85,  267§,  272,  275 

—  conduit,  277§ ;  cones,  conditions 
determining  their  forms,  274-276 ; 
stalactites  and  stalagmites,  294*, 
295,  324 

—  streams,     287*-291,     293,     294, 
295 

Layers,  76§,  91,  92§  (structure) 

Lead  mines,  Illinois  and  Wisconsin, 
342,  522  ;  Missouri,  342, 522 ;  New 
York,  542 ;  Kocky  Mtn.  region, 
876 

Leadville  mines,  340,  341*,  343; 
region,  304,  342,  876 

Leaia  tricarinata,  691 

Lecanocrinus,  550 

Leclaire  limestone,  543 

Leda,  602,  621,  917 ;  amygdaloides, 
925;  arctica,  984;  mater,  916; 
minuta,  983,  984;  multilineata, 
916;  ovum,  790;  pernula,  983, 
984 ;  truncata,  984 

Leech,  423 

Leiocidaris  hemigranosa,  837 

Leiopteria,  621 ;  laevis,  602 

Leiorhynchus  limitare,  602,  612  ; 
mesacostale,  612,  620,  621  ;  quad- 
ricostatum,  612*,  620 ;  sinuatum, 
621 

Leitha  limestone,  926 

Lemberg  chalk,  866 

Lemuravus,  918 

Lemuroids,  917 

Lemurs,  54 

Lena  River,  30 

Lenticular  mass,  92*§ 

Lepadocrinus,  562  ;  Gebhardi,  562 

Lepas  family,  600 

Leperditia,  481,  509,  516,  517,  562, 
567  ;  alta,  556*,  557  ;  amygdalina, 
503 ;  Anna,  499*  ;  Argenta,  476, 
477* ;  armata,  515 ;  Baltica,  552, 
569  ;  Cambrensis,  481 ;  Canaden- 
sis,  502*,  503,  515 ;  dermatoides, 
474*  ;  fabulites,  508*,  515  ;  Key- 
serlingi,  568 ;  nana,  502* 

Lepidodendrids,  664,  684,  698,  712, 
718,  750 

Lepidodendron,  610,  611,  627,  628, 
639,  645,  654,  658,  667*,  668*,  689, 
698,  699,  704  ;  aculeatum,  645,  646, 
668*,  688,  689  ;  acuminatum,  646 ; 
Chemungense,  609*,  610 ;  clypea- 
tum,  668*,  688,  689  ;  corrug'atum, 
611,  645;  costatum,  645;  dicho- 
tomum,  645,  688,  689 ;  diplostegi- 
oides,  645;  forulatum,  645; 
Gaspianum,  583*,  595,  611,  622; 
lanceolatum,  669*  ;  modulatum, 
688,  689  ;  obovatum,  645,  689  ; 
obscurum,  645 ;  primaevum,  595*, 
601,  610  ;  rimosum,  689  ;  squaino- 
sum,  699;  Sternbergii,  668,  688, 
689  ;  tetragonum,  645 ;  turbina- 
tum,  645 ;  Veltheimanum,  626, 


645,    668*,    688,    689,    699,    704; 

vestitum,  689  ;  Wortheni,  645 
Lepidomelane,  65§ 
Lepidophloios,  689,  699  ;   laricinus, 

689 

Lepidophyllum,  668,  699 
Lepidopters,  419,  679,  900 
Lepidosiren,  54,  417,  418 
Lepidosteus,  59,  73,  417*,  901,  926; 

osseus,  417* 
Lepidostrobus,  645,  668  ;  hastatus, 

669* 

Lepidotus,  783 
Lepidoxylon,  673 
Lepisma,  419,  702 
Lepta-na,  503,  520,  521,  562,    568, 

579;  laticosta,   626;  Murchisoni, 

626 ;  rhomboidalis,  507*,  514,  520, 

548*,  551,  562,  567,  568,  572,  590 ; 

sericea,  503,  507*,  514,  520,  521, 

522,  524,  550 ;  transversalis,  503, 

568 ;  Verneuili,  568 
Leptauchenia,  918 
Leptictis,  918 
Leptocardians,  414,  418 
Leptochoerus,  918 
Leptocladus,  789 

Leptocoelia,  579,  627 ;  flabellites,  579 
Leptodesma,  620,  621 ;  lichas,  618*  ; 

spinigerum,  621 
Leptolepis,  699 
Leptomeryx,  918 
Leptomitus  Zittelli,  470* 
Leptophlreum,    590 ;     rhombicum, 

622 

Leptophractus  obsoletus,  682 
Leptosolen  biplicata,  854 
Leptostrophia,    579;    Becki,    579; 

perplana,  579 
Leptotragulus,  907,  918 
Leptynyte,  S3§ 
Lepus,  918 
Lesleya,  639 
Lessonia,  155 

Lestosaurus,  848  ;  simus,  849* 
Lette  Island,  296 
Lettenkohle,  755,  769,  774 
Leucite,  65§,  77,  81,  85,  86,  88,  273, 

274;  rocks,  81,  85 
Leucitophyre,  85§ 
Leucitophyric,  77§ 
Leucityte,  86§ 
Leucotephryte,  «85§ 
Leucozonia  biplicata,  915 
Levant  series,  728 
Level,  changes  of,  now  in  progress, 

348,  349*,  350 

Level  of  no  strain.     See  Zero  strain 
Levis     formation,    490,    496,    497, 

527* 

Lewis  Island,  456 
Lewisian    Gneiss,    440    (Archaean 

synonymy) 

—  group  of  Murcbison,  456 
Lherzolyte, 
Liard  River,  746, 
Lias    (Liassic),    77"5;    in    Western 

America,  808,  809 
— ,  White,  774,  790 
Liassian  of  D'Orbigny,  775 
Libellula,  783* ;  Brodiei,  783 
Liberty  Cap,  geyser  cone,  807* 


!§      \ 
46,  738 

),    775;    in 


Libocedrus,  939  ;  decurrens,  939 

Lichas,  520,  521,  551,  561,  568,  586, 
591 ;  Anglicus,  567 ;  Bigsbyi,  561 ; 
Boltoni,  549*,  551 ;  cucullus,  515 ;. 
grandis,  586,  587*  ;  gryps,  587* ; 
hylaeus,  587* ;  laxatus,  567 ;  pus- 
tulosus,  561;  Ribeiroi,  521; 
Trentonensis,  508*,  509,  512,  515 

Lichenocrinus,  516 

Lichens,  58,  75  (ash),  126, 136  (ash), 
436§,  688,  946 

Life,  characteristics  of,  9§,  413 ;  its 
chemical  work,  136-137  ;  contribu- 
tions to  rock-making,  71-75;  de- 
structive effects  of,  157 ;  protec- 
tive effects,  155 ;  transporting  ef- 
fects, 156 

— ,  disappearance  of,  403,  404 ;  at 
close  of  Mesozoic,  876-877;  at 
close  of  Paleozoic,  727,  728,  735- 
736 ;  at  close  of  Cretaceous,  576 

— ,  evolution  by  variation,  1020 

— ,  general  laws  as  to  progress  in, 
1028;  geographical  distribution 
of,  52-60  ;  injury  to,  from  mineral 
and  marine  waters,  122 ;  introduc- 
tion of,  397,  458 

— ,  lowest  species  the  best  rock- 
makers,  142 ;  mechanical  work 
and  rock  contributions,  117,  118, 
140-158 

— ,  oceanic,  distribution  of,  illus- 
trated by  the  physiographic  chart, 
47* 

— ,  system  of,  animal  kingdom, 
413;  vegetable,  434;  cephaliza- 
tion,  437 

Ligerian,  859,  866 

Light  affecting  life,  52 

Lighthouses  and  waves,  217,  218 

Lightning,  effects  of,  upon  rocks 
and  sand-heaps,  265,  266 ;  heat  of, 
258 

Lignite,  816,  817,  819,  821,  825,  829, 
830,  887,  890,  922 

Lignitic  beds,  828,  829,  885,  887 
(Brandon),  889,  895,  896,  921, 
922 

Ligumen  planulatum,  854 

Ligurian  group,  884 

Lily  Encrinite,  770 

Lima,  756,  757,  75\  780,  834,  860 ; 
crenulicosta,  854 ;  decussata,  866 ; 
gigantea,  779*,  790;  Kimballi, 
837;  proboscidea,  791;  punctata; 
791;  retifera,  690;  rudis,  790; 
Shastaensis,  837;  striata,  774; 
Taylorensis,  759* 

Limacina,  424 

Limbs.  See  Merosthenic;  Podos- 
thenic ;  Prosthenic ;  Urosthenic 

Limestone,  62§,  78-80 ;  ferriferous, 
decaying  to  limonite,  126*  ;  meta- 
morphic,  309,  310,  315;  rate  of 
formation,  716 ;  teachings  of  coral 
reefs  on,  151 

—  caverns,  883 

Limnadia,  486 

Limnsea,  152;  caudata,  926;  desid- 
iosa,  966 ;  humilis,  966 

Limnophysa  desidiosa,  966;  hu- 
milis, 966 


1064 


INDEX. 


Limnopus  vagus,  684* 

Limnoria,  158 

Limnosyops,  918 

Limonite,  71  §  ;  from  decaying  fer- 
riferous limestone,  126* 

Limulids,  Paleozoic,  676,  701*,  719 

Limuloids,  419, 420§,  423,  455 ;  deri- 
vation, 720-721 

Limulus,  59,  420,  496,  556,  565,  616, 
676,  720,  721,  724 ;  polyphemus, 
420 

Lingula,  59,  72,  73  (composition  of 
shell),  425*§,  468,  481,  487,  493, 
496,  516,  521,  550,  606,  612,  621, 
719 ;  acuminata,  500 ;  cuneata, 
538,  544*,  549  ;  Huronensis,  503  ; 
lamellata,  551 ;  lata,  567 ;  Lewisii, 
567;  Lyelli,  503;  minima,  567; 
nitida,  840  ;  ovalis,  73 ;  quadrata, 
507*,  514,  516;  spatulata,  612*, 
620 

—  family,   779,  840   (Mesozoic   and 
Paleozoic  contrast) 

—  flags,  481,  489,  573 
Lingulella,  425§,  481,  482;  ccelata, 

471* ;  Davisi,  481*,  520 ;  Dawsoni, 

475*  ;  ella,  471* ;  ferruginea,  481 ; 

lowensis,  515;  prima,  478*;  pri- 

mseva,  481 

Lingulepis  antiqua,  478* 
Lingulocaris,  482 
Linnarssonia  pretiosa,  500 ;    trans- 

versa,  475* 
Linton,  Ohio,  fossils,  661,  679,  681, 

682,  692 

Liochlamys  bulbosa,  917 
Liodon,  864 
Lion,  54 
Lipari,  276 

Liquidambar,  921,  922 
Liriodendron,  837,  921 ;  Meekii,  837, 

838* ;  simplex,  837,  838* 
Lisbon,  earthquake,  in  1755,  373 
Lisbon  beds,  889 
Listriodon,  927 
Lithia,  61§,  321 
Lithia  Well,  Ballston,  121 
Lithic  era,  440 
Lithistids,  777,  860* 
Lithium,  61, 335  ;  salts,  119 
Lithobius,  724 

Lithodesare,  59  ;  Agassizli,  59 
Lithodomous  shells,  348 
Lithodomus,  157 ;  praelongus,  867 
Lithographic   limestone,    637,   646, 

776,  788 

Lithoidyte,  84§,  337 
Lithomantis  carbonaria,  702 
Lithomylacris,  691 
Lithophis,  901 
Lithophysae  (lithophyses),  289, 337§, 

338 ;  of  Obsidian  Cliff,  337*,  338 
Lithosphere,  61§ 
Lithostrotion,  640,  659,  674,  700,  711, 

718;  Canadense,  639*,  640,  646; 

mammillare,  659  ;  proliferum,  646 
Lithostrotion  beds,  688 
Litoceras,  501 
Litssea  Weediana,  889 
Little  Ararat,  265,  296  (height) 

—  Elko  Range,  866 

—  Metis,  Can.,  497,  500 


Little  Missouri  River,  266 

—  River  group,  N.  S.,  593 
Littoral  and  abyssal  deposits  com- 
pared, 151 

—  currents,  212  ;  zone,  56 
Littorina,  130 ;  palliata,  984 
Lituites,   499,    511,  520,    521,   567, 

568 ;  Americanus,  573  ;  Ammo- 
nius,  511 ;  Farnsworthi,  500 ; 
giganteus,  567,  573 ;  imperator, 
499,  500 ;  Marshi,  551 ;  undatus, 
514 

Lituola  nautiloidea,  432*,  860* 

Liverworts,  436 

Livingston  beds,  828,  839,  875 

Lizards,  54,  415,  768,  787,  849 

Llama,  54,  910,  924,  1002 

Llandeilo  group,  463,  515,  519,  568 

Llandovery  group,  518,  520,  534, 
567,  569 

Llano  Estacado,  912 

Llano  group,  447,  469 

Loa,  Mt.,  26,  27, 179, 268*  269*  270, 
275, 276,  279,  286*,  288,  304 

Loam,  76 

Lob-worm,  156,  420*,  423 

Lobster,  78,  420,  421,  438,  717,  771, 
783 

Locusts,  419,  677,  679 

Lodes,  327, 331§ 

Loess,   81§,  152,  195,  196* 

Loess,  of  the  Mississippi,  fossils  in, 
964,  966,  973 

Loftusia  Columbiana,  674,  690 

Loganellus,  503 

Loganite,  454 

Loganograptus  Logani,  498* 

Logs,  156,  189,  191 ;  carbonized  at 
one  end  and  silicified  at  the  other, 
143  ;  in  the  Coal-measures,  654 ; 
see  also  Wood 

Loire  River,  peat  marsh  of,  154 

Loligo  vulgaris,  424* 

Lombardy,  769,  774 

London,  17 

London  basin,  920,  923,  925;  clay, 
920§,  923,  925 

London-Paris  basin,  857,  919,  920, 
936 

Lone  Mountain,  495;  limestone, 
516,  733 

Long  Island,  18*,  41,  162,  167,  205, 
206,  211*,  223,  224,  225,  350 ;  ori- 
gin of  north  bays  of,  949 ;  clay- 
beds,  822,  823,  837,  &39 ;  drift,  942 
-  — ,  Archaean  of,  444 ;  Cretaceous, 
822,  823,  839,  872 ;  beds  upturned 
during  the  Tertiary,  934,  1022*; 
Glacial,  949,  960,  962,  964,  970 

Sound,  18*,  211*,  226*,  227, 

444,  461  ;  a  river  channel  in  the 
Glacial  period,  949 ;  tides  of,  211, 
214,  215,  216,  226 

Longmynd  rocks,  480,  534 

Lonsdalia,  718 

Loochoo  Mts.,  40 

Loon,  852 

Lophiodon,  923,  924,  925 ;  minimus, 
926 

Lopholatilus,  56 

Lophophyllum,  674 ;  proliferum, 
674 


Lorraine,  738,  792 
Lorraine  shales,  489,  494 
Los  Carlos  Mts.,  340 
Louisiade  Islands,  36,  38 
Louisiana,  mean  height  of,  28 
Louisiana  limestone,  Missouri,  687 
Loup  Fork  beds,  829,  884,  885,  886; 

fossils  of,  894,  895,  911,  919 
Low-lands,  23§ 

Lower  California.     See  California 
Lower  Helderberg  period,  558 
,  Devonian  relations  of  fauna, 

569-570 

Lower  Silurian  era,  489 
Lowlands,  28 
Loxoinma  Allmanni,  703 
Loxonema,  520,  562,  590,  599,  618, 

621,  625,  642,  700 ;  priscum,  601 ; 

semicostatum,  690 ;  sinuosum,  567 
Loxotrema,  916 
Loyalty  Islands,  36 
Lucia  Island,  881 
Lucina,    602,    780,   867,  916;    ano- 

donta,   917 ;    Claibornensis,    916 ; 

contracta,    917 ;    cribraria,    917 ; 

occidentalis,     855 ;     Portlandica, 

791 ;  serrata,  926 
Ludian  beds,  926 
Ludlow  beds,  463,  563,  578 
Lumachelle  limestone,  792 
Lunatia,  916;  Grcenlandica,  983, 984 ; 

heros,  983,  984 ;  obliqua,  854 
Lung  fishes,  417§,  587,  618 
Lunulicardium,  602,  621 ;  acutiros- 

trum,  620  ;  fragile,  612*,  620 ;  or- 

natum,  620 
Lutetian  group,  925 
Lutraria  papyria,  916 
Luzon,  40,  920 

Luzula,  240 ;  hyperborea,  945 
Lychnocanium  lucerna,  438* 
Lycopodites,  610,  668 
Lycopodium  chamsecyparissus,  75; 

clavatum,  74;  complanatum,  75; 

dendroideum,  75, 668, 669 ;  selago, 

946 
Lycopods,  58,  74,  75,  434,  436§,  663, 

667,  668,  672,  711,  712,  713;  ash 

of,  74,  75 ;  spores,  composition  of, 

713  ;  Clinton,   549  ;   Corniferous, 

583*;    Hamilton,    595*;    Subcar- 

boniferous,    639,    645;    Carbonif- 
erous, 666,  667,  668* 
Lyell  (Mt.),  glaciers  of,  240,  945 
Lykens  Valley  coal,  656 
Lynton  group,  625 
Lyre  bird,  54 
Lyria  costata,  898*,  916 
Lyrodesma,  516 ;  cuneatum,  567 
Lytoceras,   760,  793,   794;  Batesii, 
"*837 ;  Jurense,  790 

Macacus,  55 
McGregor  coal-bed,  658 
Machaeracanthus  sulcatus,  589* 
Machaerodus,   911,   919,  927,   1000; 

Floridanus,  1001 ;  latidens,  1006 
Mackenzie  River,  40,  171,  859,  580, 

590,  592,  593,  594,  602,  830 
—  Laramie  area,  827 
Mackerel,  812,  862 
Mackinac,  552,  580,  628 


INDEX. 


1065 


^Maclurea,  493,  499,  516,   51T,   520; 

arctica,  525 ;  cuneata,  515 ;  Logani, 

502* ;  magna,  491,  502*,  503,  514, 

524,    525;    matutina,    500,    517; 

subrotunda,  515 
Maclurea  limestone,  494 
Macoma  calcarea,  984 ;  fragilis,  983, 

984 ;  fusca,  984 ;  sabulosa,  983,  984, 

995 

Macquarie  Islands,  37,  39 
Macrauchenia,  1002 
Macrocheilus,    599,    621,   642,   700; 

fusiformis,  675*,  690  ;  Newberryi, 

690 ;  ventricosus,  690 
Macrochilina  subcostata,  601 
Macrocyclis  concava,  966 
Macrocystis  pyrifera,  156 
Macrodon,  621 ;    carbonarius,  675*, 

690 

Macropetalichthys   Sullivanti,  588* 
Macropterna  divaricans,  752* 
Macropus,  1006 
Macroscopic  texture,  76§ 
Macrostachya,  699 
Macrotheriura,  918,  925 
Macrurans,  52,  59,  421  §,  438§,  439, 

615,  701*,  707,  720,  771*,  783* 
Mactra  alta,   855;    delumbis,  917; 

ovalis,  983 
Madagascar,  296    (volcanoes),  737, 

873 

Madeira,  297 

Madison  River  geysers,  305,  307 
Madrepora     palmata,    analysis    of 

coral  of,  72 
Maestricht  beds,  Maestrichtian,  815, 

858,  859,  864,  866,  870 
Magellan,  Straits  of,  858,  867 
Magellania,  426§* ;  flavescens,  426* 
Maggiore,  Lago,  199 
Magnesia,  61§ 
.Magnesian    limestone,    78§,     131; 

Cambrian,  468 ;  Lower  Silurian, 

491,  493,  501,  732 
—  salts,  of  the  ocean,  320 
.Magnetic  iron  (magnetite),  70§,  170, 

223,  578 

Magnetitic  rocks,  83§,  84 
Magnolia,  812,  837,  840,  859,  921 
Magothy  formation,  819  ;  River,  819 
Mahoning  sandstone,  652,  656 
.Maine,  23,  85,   158,  160,  265,  461; 

fiords  of,  444,  948 ;  upturnings  in, 

630,  732 
— ,  Archaean  in,  444 ;  Paleozoic,  461 ; 

Cambrian,  466 ;  Lower  Silurian, 

493 ;  Niagara,  539,  541,  544,  552 ; 

Clinton,  539,  552 ;  Lower  Helder- 

berg,    544,    552,    558,    559,    562; 

Oriskany,    577,    579 ;    Devonian, 

622,  630 ;  Glacial,  948,  949 
Maine- Worcester  trough,  461 
Malacca,  22,  38,  41 
Malachite,  342 
Malaspina  Glacier,  238,  239* 
Maldive  Islands,  145,  150,  787 
Maleri  beds,  773 
Mallotus  villosus,  984 
Malm,  776 
Malocystites  Barrandi,  503 ;  Murchi- 

soni,  502*,  503 
Malta,  921 


Mammals,  geographical  distribu- 
tion, 54,  409*,  414;  relation  to 
Amphibians,  726,  794,  795,  796; 
increase  in  size  of  brain  during 
the  Tertiary,  913,  914;  reign  of, 
878,  879  ;  Triassic,  754*,  773,  797  ; 
Jurassic,  767*,  789* ;  Cretaceous, 
852,  871 ;  Tertiary,  902,  920,  923, 
927 ;  evolution  of  Eocene,  928 

— ,  Tertiary  and  Quaternary,  rela- 
tions of,  1017 

—.Quaternary,  950,  997;  culmina- 
tion of,  1016 ;  degeneration  in 
some  Quaternary  species  of,  1007 

Mammoth  coal-bed,  650,  652,  653, 
656,  660,  663 

Man,  1008 ;  relation  to  Quadru- 
mana,  1017,  1036;  Pleistocene, 
1008 ;  origin,  1036 

Man-apes,  54,  1036 

Manasquan  group,  821 

Manatus,  925 

Manchuria,  32,  696 

Mangaia  Island,  elevation,  350 

Manganite,  71  § 

Mangrove,  155 

Manis,  54 

Manitoba,  rainfall  in,  944 ;  Trenton 
in,  515 ;  Lower  Helderberg,  561 ; 
Devonian,  594,  597,  601,  602 ;  Cre- 
taceous, 830,  856 ;  Glacial,  945 

Manitoba  (Lake),  594 

Manitou  Park,  876 

Manitoulin  Islands,  522,  540,  542 

Mantellia,  777  ;  inegalophylla,  776*, 
777 

Manteodon,  918 

Manti  beds,  893 

Mantle,  425§ 

Map  of  Apia  and  Menchikoff,  145* 

— ,  bathymetric,  17,  19,  following 
20* 

—  (bathymetric)  of  submerged  At- 
lantic border,  18* 

—  of  the  Atlantic  coast-region,  224* 

—  of    Mont    Blanc  glaciers,   235*, 
236* 

—  of  Triassic  area  of  Connecticut, 
801* 

—  of  harbor  at  mouth  of  Connecti- 
cut, 226* 

— ,  geological,  of  England,  693,  694* 

—  of  Fiji  Islands,  150* 

—  of  the  Great  Lakes,  201* 

—  of  western  Greenland,  240,  241*, 
249* 

—  of  Hawaii,  268* 

—  of  Hawaiian  Islands,  36* 

—  of  harbor  at  mouth  of  Housa- 
tonic  River,  227* 

—  of  land  and  water  hemispheres, 
16* 

—  of    Long    Island    Sound,    Long 
Island,  and  the  Atlantic  Border, 
17§,  18*,  211* 

—  of  Loyalty  group,  85* 

—  of  Marquesas  Islands,  36* 

—  of  Mars,  396* 

—  of  Maui,  179* 

—  of  delta  of  the  Mississippi,  197* 

—  of  New  Caledonia,  35* 

—  of  New  Haven  harbor,  226* 


Map  of  trap  dikes,  near  New  Haven, 
299* 

—  of  New  Hebrides,  35* 

—  of  part    of   eastern   New   York 
and   western  Connecticut,  529*, 
530§ 

— ,  geological,   of  North   America, 
412*,  635 

—  of  North  America  after  the  Ap- 
palachian   revolution,   734,   735*, 
739 

—  of  North  America   in    the  Ar- 
chaean, 442,  443* 

—  of  North  America  at  the  com- 
mencement of  the  Carbonic  era, 
633* 

—  of  North  America  in  the  Creta- 
ceous, 812,  813*,  814 

—  of  North  America,  Glacial,  illus- 
trating the  phenomena,  after  944 

—  of  North  America,  Tertiary,  881*, 
883 

—  of  North  America,  Upper  Silu- 
rian, 535,  536*,  575,  633,  634 

—  of  Oahu,  292* 

—  of    courses    of    Pacific    island 
chains,  37*,  39* 

— ,  topographical,  of  Pennsylvania, 
357,  729,  730*,  731 

—  of  Pennsylvania  coal-fields,  649* 

—  of  courses  and  flexures  of  ridges 
in  central  Pennsylvania,  729,  731* 

—  of  Mt.  St.  Elias  region,  239* 

—  of  Tahitian  Islands,  36* 

—  of  Tahiti,  180 

—  of  United  States,  412*,  799 

—  of  Wasatch  Mts.  and  Utah,  360* 

—  of  ti,p  world,  on  M creator's  pro- 
jection, 17§,  47* 

— ,  physiographic,  of  the  world,  46, 
47*,  350 

—  of  Yellowstone  Park,  306* 
Maple,  837,  859,  879 
Marble,  76,  79*,  131 

Marble     Canon,     186,     187*,     862, 

363* 
Marcasite,  70§,  123,  125,  126,  258, 

331,  342,  663 
Marcellus  epoch,  410,  576;   shale, 

576,  593§ 
Marcy,  Mt.,  452 
Mareniscan,  446 
Margaric  acid,  124 
Margarita  Nebrascensis,  841*,  855 ; 

striata,  984 ;  varicosa,  984 
Margaritana  margaritifera,  950 
Margarite,  320 
Margaritella,  916 
Margaritina  confragosa,  966 
Marginella,  917 
Mariacrinus,  577 
Mariposa  region,  748,  760,  837 
Marl,  68§,  79§  ;  Tertiary,  820,  854 
Marlstone,  411,  775 
Marly  clay,  81§ 
Marlyte,  552,  553 
Marmot,  156 
Marquesas  Islands,  297,  850;  map 

of,  36*,  38 
Marquette   iron    region,   445,  446, 

450 
Marquettian,  446 


1066 


INDEX. 


Mars,  density  of,  16 ;  oblique  feat- 
ure-lines on,  395,  396* 

Marsh  gas,  124,  523 

Marsh  ore,  71§,  344, 455.  See  also 
Bog  ore 

Marshall  group  (grit  and  sand- 
stone), 638 

Marshall  Islands,  395 

Marsilea,  718  ;  quadrifolia,  436* 

Marsileacese,  519 

Marsipobranchs,  418§ 

Marsupials,  53,  54,  55,  415§.  See 
Mammals 

Marsupiocrinus  caelatus,  567 

Martha's  Vineyard,  Cretaceous  of, 
822,  837,  838;  Tertiary  of,  881; 
891 ;  upturning  of  beds,  934,  1022 

Maryland,  mean  height  of,  23; 
Cambrian  in,  465,  466,  467 

Mascarene  Islands,  787 

Massachusetts,  23  (height),  85,  453, 
496;  coal-beds,  634,  646,  657; 
iron  ore  beds,  127 ;  kaolin  beds, 
134 ;  marbles,  524,  530,  531 ;  Cam- 
brian in,  310,  466,  467,  471,  475; 
Taconic,  491,  517,  524,  528,  530, 
531 ;  Trenton,  495  ;  Triassic,  740, 
741,  742,  750,  753,  800,  802 

—  Bay,  444,  461,  536 
Massawipi  Lake,  558 
Massillon  coal,  657 

Massive  limestone,  76,  78§  ;  quartz- 
yte,  82§ ;  rocks,  76,  78§  ;  struc- 
ture, 92§ 

Mastodon,  919,  927,  1000,  1011 
Americanus,  998* ;  Arvernensis 
927;  angustidens,  927;  Borsoni 
927 ;  Floridanus,  1001 ;  longiros 
tris,  927  ;  mirificus,  911,  912 
proavus,  911 ;  tapiroides,  927 

Mastodons,  141,  402,  911  (first),  924, 
925 

;odonsaurus    giganteus,    772* ; 
Jaegeri,  774 

Mastogloia,  164*,  165 

Matheria  variabilis,  478* 

Matinal  of  Eogers,  490,  494,  728 

Matterhorn,  189,  237 

Matthews'  Landing  clays,  885,  888 

Mauch  Chunk  group,  410,  634,  636, 
644,  728 

Maudunian  group,  925 

Maui,  150,  172 ;  map  of,  179*,  182 ; 
cone  of,  270 

Maumee  Eiver,  947 

Mauritius,  volcanoes  of,  277,  296, 
1019 

Mauvaises  terres,  894 

May-fly,  419,  600 

May  Hill  sandstone,  518,  563.  566, 
569 

Mayencian  group,  926 

Mazonia  Acadica,  691 ;  Woodiana, 
691 

Mazzalina  pyrula,  916 

Meadville  group,  638 

Medina  epoch,  535,  570 

—  sandstone,  538,  542 
Mediterranean     Cretaceous    basin, 

857,  859,  872,  873;    earthquakes 
of,  374;  region,  769,  791,  793,  861 

—  Sea,  20,  21,  22,  34,  45  ;  tempera- 


ture of,  49  ;  salinity  of,  121 ;  vol- 
canoes of,  295 

Medlicottia  Copei,  685*,  686 
Medusae,   55,  418,  419,  429*,  430§. 

479,  480,  482 
Medusites,  482 
Meekella  Shumardana,  685 ;  striato- 

costata,  690 

Meekoceras  aplanatum,  757 
Megadactylus,  753 ;  polyzelus,  753 
Megalaspis,  521 
Megalichthys,  621,  692,  702 
Megalocnus  rodens,  1001 
Megalodon  triqueter,  774 
Megalomus  Canadensis,  548*,  551 
Megalonyx,   912,    919,    1000,    1001, 

1003  ;    Jeffersonii,    1000,    1001* ; 

Leidyi,  1001 

Megalopteris,  689 ;  fasciculata,  645 
Megalosaurs,  786,  828 
Megalosaurus,  765,  766,  790 ;  Bredai, 

864 ;  Bucklandi,  785  (time  range) ; 

Dunkeri,  863 
Megambonia,  562 
Megaphyton,    699;    McLayi,   669*, 

689 ;  protuberans,  645 
Megaptera  longimana,  983 
Megathentomum,  679 ;  pustulatum, 

691 

Megatheridse,  1000 
Megatherium,     1000,    1002,    1004; 

Cuvieri,  1002*  ;  mirabile,  1000 
Megistocrinus,  590,  602 
Meionite,  65§ 
Meizoseismic  curve,  375§ 
Melania  costata,  926 ;  fasciata,  926 ; 

inguinata,  925 ;  turritissima,  926 
Melantho  subsolida,  966 
Melaphyre,  87§ 

Meleagris  altus,  1002 ;  celer,  1002 
Melocrinus,  550,  562,   577 ;  Clarki, 

621 ;  nobilissimus,  560 
Melongena  crassicornuta,  916 
Melonites  multiporus,  641*,  646 
Melosira  distans,  163,  164* ;  granu- 

lata,   163,   164*;    decussata,   163, 

164*;    Marchica,  163,  164*;  sul- 

cata,  437*,  894* 
Melville  Island,  659,  689 
Memphremagog  (Lake),  531,    580, 

591,  630 

Menaccanite,  70§ 
Menacodon  rarus,  767* 
Menchikoff  Island,  145*,  150 
Mendip  Hills,  695 
Mendoza  earthquake,  349 
Menevian  group,  481 
Menilite,  920 

Meniscoessus  conquistus,  852 
Meniscotherium,  917 
Meniscus  limestone,  543,  550 
Menobranchus  lateralis,  682 
Menocephalus,  503 
Menominee,  446 
Menurids,  54 
Merced  group,  884,  892 
Mercer  coal-beds,  656 
Mercian,  631,  738 
Mercury,  density  of  planet,  16 
Mercury  mines  of  California,  835 
Meretrix,  916 
Meridian  series,  728 


Merista,  642  ;  plebeia,  625,  628 

Meristella,  562,  579,  642 ;  angusti- 
frons,  567;  didyma,  567;  Isevis, 
560*,  562;  nasuta,  590,  591,  592; 
subundata,  520;  sulcata,  557> 
560* ;  tumida,  568 

Meristina  nitida,  548*,  551 

Merjelen  (Lake),  238 

Merocrinus,  516  ;  typus,  514 

Merosthenic,  717§,  796,  870,  871 

Merychyus,  919 

Merycochcerus,  918,  919 

Merycopotamus,  927 

Mesa,  185§,  186*,  300 

Mesabi  Kange,  446 

Mesalia  Claibornensis,  897*,  916;; 
obruta,  916  ;  vetusta,  916 

Mesnard,  446 

Mesodectes,  918 

Mesodevonian,  576§ 

Mesodon  albolabris,  966;  diastema- 
ticus,  836 ;  Dumblei,  836 ;  pro- 
fundus,  966 

Mesohippus,  908,  912,  913*,  918 

Mesonacis  Vermontana,  473* 

Mesonyx,  918 

Mesoreodon,  918 

Mesosaurus,  706 ;  tumidus,  687, 
688* 

Mesothyra  Neptuni,  600;  Oceani, 
600,  615* 

Mesozoic  time,  738 

Messinian  group,  927 

Metacoceras  cavatiforme,  690; 
dubium,  691 ;  Hayi,  691 ;  incon- 
spicuum,  691 ;  Walcotti,  691 

Metadiabase,  86§ 

Metadoxides,  482 

Metagene,  880§ 

Metalophodon,  918 

Metals  heavier  than  iron  not  erup- 
tive, 876 ;  native,  331,  332 

Metamorphic  rocks,  76§,  82 

—  and  igneous,  relations  of,  326, 
327 

Metamorphism,  309 ;  dynamical, 
began  in  the  Archseozoic  era,  441 ; , 
heat  in,  311,  321-326;  local,  311, 
312-314;  metachemic,  314§,  318-- 
321;  moisture  in,  311-312;  para- 
morphic,  314§,  317-318 ;  regional, 
311,  313,  314-315  ;  statical,  began 
in  the  Lithic  era,  440;  without, 
heat,  327 

—  in  Archfean,  448,  450,  451,  453 

Metamynodon,  918 

Metapedia  Lake,  533 

Metasomatic  metamorphism,  314§ 

Meteoric  stones,  11,  876 

Meteorites,  376,  486 

Metia  Island,  133,  151  (height),  350' 

Metoptoma,  482,  514,  516 ;  alta,  501 ;. 
dubia,  503 

Meudon  chalk,  866  ;  marls,  925 

Meuse,  ratio  of  sediment  to  water, 
190 

Mexico,  25,  26 ;  snow-line  in,  234 ; 
volcanoes,  296,  937 ;  mines  of, 
338,  340;  height  of  Cretaceous 
beds,  933  ;  Archaean  in,  444 ;  Car- 
boniferous, 537,  569;  Permian, 
659  ;  Triassic,  739,  747,  755 ;, 


INDEX. 


1067 


Jurassic,  749  ;  Cretaceous,  364, 
813*,  814,  817,  818,  820,  824,  834, 
836,  874*  ;  Tertiary,  880,  885,  888, 
894 

Miacis,  918 

Miamia  Bronsoni,  679*,  691 

Miarolyte,  83 

Miascyte,  85§ 

Mica,  65§,  81 

—  dioryte,  86§ 

—  schist,  83§ 

—  syenyte,  83§  ;  trachyte,  84§ 
Michelinia,  562,  597,  640  ;  stylopora, 

601 
Michigan,  mean  height  of,  S3 ;  salt 

group,  638 
— ,  Archaean  in,  442,  445,  446,  449*, 

450,  454  ;  Cambrian  in,  464,  465*, 

468 

Michigan  Bay,  628,  633 
Michigan,  Lake,  200,  201*,  202,  540, 

635 ;    fiords  of,  947,  948 ;  glacier 

of,  968 

Michipicoten  Island,  445,  483 
Micraster,   860;    brevis,   866;    cor- 

anguinum,   866;    cor-bovis,  866; 

glyphus,  866 ;  tercensis,  866 
Microbes.    See  Bacteria 
Microblattina,  691 
Microchaerus  erinaceus,  926 
Microclaenodon,  917 
Microcline,  64§,  83,  85,  129,  821 

—  granite,  83 

Micrococcus  nitrificans,  137 
Microcoelus,  867 

Microconodon  tenuirostris,  754* 
Microdiscus,   473,  481;    speciosus, 

473* 

Microdon,  621 ;  bellistriatus,  598*, 
602 

Micro-granitic  rocks,  77§ 

Microlestes,  774,  789;  antiquus, 
773* ;  Moorei,  773 

Microlites,  77§,  266,  273,  288*,  449 

Microscopic  texture,  76§ 

Microspongia,  515 

Microsyops,  918 

Midford  sands,  775 

Midway  epoch,  884,  885,  888,  896*, 
915 

Migrations  forced  by  glacial  condi- 
tions, 945 ;  Arctic,  between  Amer- 
ica and  Europe  or  Asia,  946,  950 

Mill  Creek  beds  (group),  840,  872 

Millepeds,  419,  723 

Millepores,  72,  130,  142,  431§ 

Millerite,  637 

Millstone  grit,  SO,  410 

Millstones,  82 

Milo  Island,  volcanoes,  296 

Minas  Basin,  N.S.,  350,  741 

Mineral  charcoal,  662 

—  oil  and  gas,  62,  74,  80,  124,  138; 
from  the  Trenton  limestone,  522- 
523  ;  from  Salina  group,  554 ;  from 
the  Devonian,  606  ;  map  of  areas 
in  Pennsylvania,  730* 

—  springs,  119,  128,  320;  analyses, 
121 

Minerals,  63;  making  of,  317, 318, 323 
Mines,  temperature  in,  257,  258 
Minette,  83§ 


Mingan  Islands,  492,  493,  497,  500, 
501,503 

Minnesota,  height  of,  23 ;  rain- 
fall, 944 ;  Archaean  in,  446.  448* ; 
Cambrian,  468,  469,  478,  484 ;  Cal- 
ciferous,  491,  493;  Trenton,  494; 
Niagara,  540 ;  Subcarboniferous, 
634 ;  Glacial,  945,  968 

Minnesota  River,  947 

Minyros  Island,  296  (volcanoes) 

Miocene  lake  basins,  882,  933 

—  period,  880§,    881*,    883;  lacus- 
trine, 893-895 

Miohippus,  911,  912,  913*,  918,  919  ; 
annectens,  894 

Miohippus  beds,  886,  894 

Miolophus,  925 

Mispec  conglomerate  and  slate,  594 

Mississaga  Eiver,  445 

Mississippi,  mean  height  of  the 
state,  23;  Cambrian  in,  466; 
Subcarboniferous,  638,  648;  Car- 
bonic, 635;  Cretaceous,  638,  819, 
823,  845,  854,  888 ;  Tertiary,  884 ; 
Glacial,  945 

—  Eiver,  24,  29,  30,  31;  pitch  and 
amount   of  discharge,   173,  190; 
delta  of,  197;  headwaters  in  the 
Glacial     period,    947,    948,    964; 
Southwest  Pass  of,  198 

Mississippian  period,  632 
Missouri,  mean  height  of,  23 ;  iron 

mountains,  444,  449  ;  lead  mines, 

134,  342,  522 

—  Eiver,  29  ;  discharge  and  pitch, 
173 ;  headwaters  in  the  Saskatch- 
ewan during  the  Glacial    period, 
964 

— ,  region  of  Upper,  829,  841,  844, 

855,  893 
Mitchell,  Mt.,  27 
Mites,  420§ 

Mitoclema  cinctosum,  503 
Mitra,    916,    922;   cellulifera,    916; 

conquisita,  916  ;  scabra,  926 
Mixodectes,  917 
Moa,  1014 
Modiola,  525,  757,  916,  917 ;  Bran- 

neri,  836 ;  minima,  774  ;  plicatula, 

994  ;  Shawneensis,  690  ;   Wyom- 

ingensis,  690 

Modioloides  priscus,  472* 
Modiolopsis,  481,   516,    520;    com- 

planata,  567;    dubia,  558;    faba, 

514 ;  modiolaris,  511*  ;  orthonota, 

544*,  549 ;  primigenia,  544*,  549 ; 

subalata,  551 ;  superba,  514 
Modiomorpha,  602,  621 
Modulus  compactus,  917 
Mohawk  Eiver,  analysis  of  water 

of,  121 
Moisture  in   rocks,   122,   205,   278, 

311-312,  315,  324,  325,  334,   354, 

802 

Mokkatam,  160* 
Molasse,  920,  921  ;  Lignitic,  926  ; 

Lower,  926 ;  Eed,  926 
Molds,  436§ 
Mole,  158,  927 

Molgophis,  692  ;  macrurus,  682,  692 
Molluscoids,  140,  419,  423,  425,  526 
Mollusks,  55,  59,  72,  423 


Molokai,  292 

Moluccas,  921 

Molybdate,  340 

Mona  Series,  440 

Monads,  419 

Monazite,  85,  455 

Mongolia,  32,  83,  34 

Monkeys,  54,  55,  402,  924,  930 

Mono  Lake,  26, 132*,  138*,  276,  296, 
334 

Monoclines,  102§*,  109,  110* 

Monoclonius,  847 

Monodon,  690 

Monomyaries,  525 

Monongahela  Eiver  series,  651 

Monopleura  marcida,  836 ;  pinguis- 
cula,  886 

Monoprionidae,  498*§ 

Monopteria,  690 

Monotis,  756,  759;  Albert!,  774; 
curta,  758*  ;  decussata,  774 ;  Halli, 
685 ;  salinaria,  757 ;  septentrion- 
alis,  792 ;  speluncaria,  685  5  sub- 
circularis,  757,  758 ;  variabilis,  685 

Monotis  bed,  757 

Monotremes,  53,  54,  415,  789,  852, 
858*,  917 

Monroe  County,  Pa.,  Prosser's  sec- 
tion of,  594,  6U6 

Monson,  Mass.,  quarry,  373 

Mont  Blanc.     See  Blanc 

Montalban,  446 

Montana,  mean  height  of,  23 ;  Cam- 
brian in,  476,  477  ;  Subcarbonifer- 
ous, 639;  Carboniferous,  658; 
Triassic,  746 ;  Jurassic,  748 ;  Cre- 
taceous, Lower,  818,  820  ;  Upper,. 
825,  826,  828 ;  Tertiary,  894,  918 

Montauk  Point,  224 

Monte  Eosa.    See  Eosa 

Montebello  sandstone,  594 

Monterey  beds,  888 

Monticulipora,  505,  511,  516,  524y 
545*,  561 ;  adhaerens,  503 ;  favu- 
losa,  520  ;  fibrosa,  503  ;  frondosa, 
520  ;  lycoperdon,  524 ;  patula,  503 

Montlivaltia,  760,  777,  778  (number 
of  British);  Atlantica,  854;  cary- 
ophyllata,  777* 

Montmartre  Gypsum  beds  (gypsi- 
ferous  marls),  923,  924,  926 

Montmorenci,  fault  at,  527* 

Montrose  shales,  606 

Monument  Park,  185,  186* 

Monzonyte,  85§ 

Moon,  ^urface  of,  11 ;  density  of, 
16 

Moosehead  Lake,  577 

Moravia,  Cretaceous  in,  838  ;  Per- 
mian,  698 

Morea  cancellaria,  854 ;  naticella,  854 

Moreau  Eiver,  856 

Mormolucoides  articulatus,  750* 

Morocco,  33,  920 

Morosaurus,  763,  786,  836;  Beck- 
lesii,  863 ;  grandis,  763* 

Morris  (Mt.),  605 

Mortar,  79§ 

Mortonia  Eogersi,  898* 

Mortoniceras,  855 ;  Delawarense, 
854 ;  Leonense,  837  ;  Shoshonense, 
855 ;  Texanum,  855 


1068 


INDEX. 


Morven,  867 

Mosasaurids,  Cretaceous,  870 ;  Cre- 
taceous (Lower),  864  (first) ;  Cre- 
taceous (Upper),  826,  845,  847, 
848  (number  in  Kansas),  848*, 
849* 

Mosasaurs,  Cretaceous,  816,  826, 
867,  870 

Mosasaurus,  848  ;  Camperi,  864*, 
866;  Dekayi,  848;  major,  848; 
princeps,  848,  849* 

Moschus,  927 

Moscow  shale,  598 

Moss-animals,  427§ 

.Mosses,  53,  153,  154,  434,  436§,  677 ; 
ash,  74,  75 

Mother  liquor,  120§ 

Moths,  419 

Mount  Desert,  218,  219*,  444 

Mountain,  24§  ;  chain,  24§,  389§, 
390 

Mountain  chains,  composite  charac- 
ter of,  28*  ;  mostly  on  the  borders 
of  continents,  392 

—  limestone,  631,  632,  634,  695 

—  mass,  26,  27 

—  range,  24§,  389§,  390  ;  relations  of, 
to  denudation,  387-388 

—  slopes,    26,    27 ;     angle    of,    27, 
28 

—  system,  24§,  889§,  390 
.Mountain-making,  345 

— ,  Archaean,  451-452 ;  at  close  of 
Eopaleozoic,  526;  post-Paleozoic, 
853,  729 ;  post-Triassic,  357,  798 ; 
post-Jurassic,  809 ;  post-Meso- 
zoic,  359,  874 ;  Tertiary,  367,  369, 
982,  940 

Mountains  of  circumdenudation, 
345§  ;  of  igneous  accumulation, 
845§ ;  of  subterranean  igneous 
accumulation,  345§ 

Mouse,  53,  797 

Muck,  154§ 

Mud,  76§.   See  also  Earth  (soil) 

Mud-cracks,  94*§,  95,  140,  223,  260, 
327,  334,  464,  554,  608,  605,  742, 
745 

—  lumps,  1978,  198 

—  volcanoes,  305 

Muir  Glacier,  238,  244,  251 

—  Inlet,  238 
Mull,  867,  938 
Mullet  family,  848 
Multiplicate  species  and  structure, 

421§,  438,  439;  in  Cambrian 
486*;  in  Paleozoic,  720,  723,  725; 
in  Jura-Trias,  795-796  \  in  Creta- 
ceous, 870  ;  in  Tertiary,  912 

Multituberculates,  917 

Murchisonia  angulata,  567 ;  Anna, 
500;  articulata,  567;  bellicincta, 
500,  507*,  514, 520 ;  bivittata,  551 ; 
corallii,  567;  extenuata,  558; 
gracilis,  514,  520 ;  macrospira. 
651;  major,  515;  Milleri,  507*, 
514,  516;  minima,  690;  minuta, 
558;  tricarinata,  514;  turbinata, 
601 

Murchisonian,  535  (Upper  Silurian 
synonymy) 

Murchisonite,  321 


Murex  Alabamiensis,  915 ;  simplex, 

916 

Muriatic  acid,  68 
Muschelkalk,  411,  769,  770,  771 
Muscovite,  65§,  83,  318, 321 ;  gneiss, 

83 ;  granite,  82 

Muscovite-and-biotite  granites,  82 
Muscovite-biotite  gneiss,  83 
Muscovy  glass,  65 
Musophyllum  complicatum,  839 
Mussel,  423 
Mustakh  Range,  240 
Mustela,  927 
Mya,  425§  ;  arenaria,  917,  983,  984 ; 

truncata,  917,  983,  984,  995 
Myacites,  757,  760  ;  Liassinus,  791 ; 

subcompressa,  760 
Myalina  angulata,  647  ;  concentrica, 

647;    Halli,    685;    perattenuata, 

685*,  690;  Permiana,  685;  recta, 

685;    recurvirostris,   690;    squa- 

mosa,  707 
Mylacris,  691 

Myliobatis,  643  ;  Edwardsi,  926 
Mylodon,  1000,  1001 ;  Harlani,  1000, 

1001 

Myocaris  lutsaria,  521 
Myophoria,    756,    759;    alta,    757; 

costata,     773;     Goldfussi,     774; 

lineata,  760,  770,  771*  ;  orbicularis, 

773 ;  vulgaris,  773,  774 
Myriapods,  418,  419§  ;  derivation  of, 

723-724;    Upper    Silurian,    574; 

Devonian,  575,  625,  721 ;    Paleo- 
zoic,   721;     Carboniferous,    657, 

674 ;  Tertiary,  922 
Myrica,  831 

Myrmecobius,  755§ ;  fasciatus,  755* 
Myrsine,  837  ;  borealis,  838* 
Myrtacese,  922 
Myrtle,  859,  921 
Mysops,  918 
Mystriosaurs,  787 
Mystriosaurus  Tiedemanni,  786* 
Mytilarca,  562,  621 
Mytiloconcha  incurva,  917 
Mytilus,  129,  525,  916;   Carteroni, 

867;    edulis,  984;    Shawneensis, 

690 ;  simplex,  867 

Naedoceras,  591 

Naiadites  carbonarius,  690 

Naked  Mollusks,  424 

Namur  dolomite,  696 

Nanafalia  beds,  888 

Nanaimo  beds,  831 

Nanawale,  285 

Nanomeryx,  918 

Nanosaurus  agilis,  765*  ;  Rex,  765 

Nantucket,  43,  210,   944  (Glacial), 

9&3,  1022 

Naphtha.    See  Petroleum 
Naples,  earthquake  of  1857,  875 
Naples  group,  603,  605,  614,  620 
Napoleon  group,  638 
Narragansett    Bay,    444,  586,   638, 

949 

Nashville  group,  489,  494 
Nasopus  caudatus,  684* 
Nassa,    916;    Dalli,    916;    scalata, 

916 
Natica,  707,  780,  916, 922  ;  abyssina, 


854 ;  clausa,  983,  984,  995 ;  Missis- 
sippiensis,  916;  pedernalis,  836; 
permunda,  916 ;  recurva.  916 

Naticella  costata,  7t3 

Naticina,  916 

Naticopsis,  690    - 

Natrolite,  68 

Nauplius,  420§,  721 

Nautiloids,  676*,  690,  727 ;  culmina- 
tion in  Carboniferous,  675 

Nautilus,  59,  424§,  425*,  501,  614, 
685,  700,  707,  727,  774,  843,  861, 
869,  922 ;  bidorsatus,  773 ;  bucci- 
num,  602;  centralis,  925;  Dani- 
cus,  866  ;  Dekayi,  842*,  854,  855 ; 
divisus,  691 ;  eccentricus,  685 ; 
elegans,  837,  855;  ferox,  501; 
Forbesanus,  690;  imperialis,  925 ; 
Jurensis,  790;  Konincki,  700*; 
Liardensis,  758;  Nordenskioldi, 
792 ;  Permianus,  685 ;  pomponius, 
501 ;  semistriatus,  791 ;  Sibyllae, 
758 ;  spectabilis,  642 

Navarro  beds,  824 

Navesink  group,  821 

Navicula,  894*;  amphioxys,  163, 
164* ;  bacillum,  163, 164*  ;  serians, 
164*,  165;  semen,  164*,  165 

Navigators  Islands.    See  Samoan 

Neaera,  916 

Nebraska,  23  (height);  Carbonifer- 
ous in,  674,  690,  691 ;  Permian, 
660;  Cretaceous,  826;  Tertiary, 
882,  893,  919,  933,  935  (elevation) 

Nebraska  lacustrine  beds,  919,  933 

Necrogammarus  Salweyi,  565 

Necroleinur,  926 

Negaunee,  446 

Neithea  grandicostata,  837;  Mor- 
toni,  867;  quinquecostata,  854, 
855 

Nelumbium  tenuifolium,  839 

Nelson  Eiver,  947 

Nematophyton,  564.  582,  590;  Lo- 
gani,  582* 

Nemodon  Vancouverensis,  837 

Neobolus  beds,  483 

Neocene,  880§,  883  - 

Neocomian  epoch,  815,  831,  857 

Neodevonian,  576§ 

Neogene,  880§ 

Neolithic  period,  1013 

Neomylacris,  691 

Neopaleozoic  time,  460,  535 

NeoplagianJax,  917,  925 

Neozoic,  880§ 

Nepheline-basalt,  88§  ;  doleryte,  87§ 

Nephelinyte,  87§ 

Nephelite,  65§  ;  rocks,  81,  84,  85 ;  ar- 
tificial formation  of,  274 ;  changes 
of,  320;  in  Archaean  rocks,  449, 
458 

Nephriticeras,  602  ;  maximum,  599 

Nephroma  arcticum,  946 

Neptunea  constricta,  915 ;  entero- 
gramma,  916 ;  Matthewsensis,  915 

Nerinea,  781,  820,  834,  861;  acus, 
836;  Austinensis,  836;  bisulcata, 
861*,  866,  867;  cultrispira,  836; 
Defrancii,  790  ;  depressa,  791 ; 
dispar,  837;  Favrei,  865;  gigan- 
tea,  865 ;  Goodhallii,  780*  ;  Meri- 


INDEX. 


1069 


ani,  865 ;  subula,  836 ;  Texana, 
835* ;  trinodosa,  791 

Nerinean  beds,  791 

Neriopteris,  689 

Nerita,  916  ;  deformis,  837 

Neritina,  854  ;  concava,  926 

Nesodon,  927 

Nesquehoning,  Pa.,  649,  650 

Netherland  coast,  378 

Netherlands,  Triassic  in,  768 

Neuropteris,  565,  639,  671,  685,  699, 
704  ;  angustifolia,  689 ;  auriculata, 
692,  704  ;  biformis,  645  ;  capitata, 
645,  689  ;  cordata,  689,  692,  704 ; 
Dawsoni,  622  ;  fimbriata,  689  ; 
flexuosa,  692.  704 ;  German,  689  ; 
hirsuta,  671*,  689,  692,  693;  in- 
flata,  689  ;  Loschii,  671*,  689,  704, 
705*  ;  polymorpha,  595*,  622  ; 
tenuifolia,  671*,  689 

Neuropteroids,  Paleozoic,  721 ;  Car- 
boniferous, 677,  679*,  691,  702 

Neuropters,  141,  419,  600,  750,  771, 
794,  900  (number  of  Florissant) 

Nevada,  mean  height  of,  23 ;  sili- 
ceous deposits  in,  152 ;  minerals 
made  at  Steamboat  Springs  in, 
323,  334;  mines,  338,  339,  340, 
341* 

— ,  Archaean  in,  447 ;  Cambrian,  464, 
469,  470,  473,  474,  477,  478,  484; 
Lower  Silurian,  495,  516;  Niag- 
ara, 541 ;  Devonian,  581,  589-590, 

592,  606 ;  Carboniferous,  658,  659, 
674 ;  Triassic,  747,  757,  758 ;  Ju-  ! 
rassic,  749,   759,    760;    Tertiary,  I 
882,  886,  893,  895,  937  (eruptions) ;  | 
post- Paleozoic  upturnings,  733 

Nevadyte,  84§ 

Neve,  283§ 

Neverita,  916 

New  Brunswick,  upturnings  in, 
527,  533,  630,  732 

— ,  Archaean  in,  444 ;  Cambrian, 
446,  466,  467,  474,  475,  476,  521  ; 
Lower  Silurian,  493  ;  Upper  Silu- 
rian in,  541,  558;  Devonian,  578, 

593,  621 ;  insects  of,  600 ;  fishes 
of,  587,  617 ;  plants  of  St.  John, 
594 ;       Subcarboniferous,       639; 
plants,    645 ;    albertite    of,    661 ; 
Carboniferous,  658,  692 

New  Caledonia,  23,  36*,  38,  145, 148, 
787,  937 

New  England,  marbles  of,  524; 
Chazy  in,  491 ;  Corniferous,  580 ; 
Glacial,  949  ;  Niagara,  541 ;  Paleo- 
zoic, 714;  Taconic,  490,  491,  495, 
527 ;  Triassic,  740 ;  Upper  Silu- 
rian, 538,  571,  572 

New  Guinea,  19,  22,  38  ;  volcanoes 
of,  296 

New  Hampshire,  23  (height),  87, 
817,  332  ;  Archaean  in,  446  ;  Cam- 
brian, 466  ;  Upper  Silurian,  531 ; 
Niagara,  541,  544,  551;  Lower 
Helderberg,  544 

New  Haven,  Conn.,  trap  dikes  of, 
299,  800*,  804* ;  kettle  holes,  993  ; 
depth  of  harbor,  226* 

New  Hebrides,  35*,  36,  38,  296  (vol- 
canoes) 


New  Ireland,   36,  38,  39 

New  Jersey,  mean  height  of,  23 ; 
coast  of,  162,  224 ;  Highlands  of, 
530 ;  marl-beds,  822  ;  clay -beds, 
822  ;  subsidence,  350,  378 

New  Jersey  Gavial,  848 

New  Mexico.  23  (height),  29,  340 
(mines),  363,  364,  747  ;  Archaean 
in,  444,  449  ;  Lower  Silurian,  495 ; 
Carboniferous,  674,  690  ;  Permian, 
660,  688;  Triassic,  746,  755,  756, 
758 ;  Jurassic,  747  ;  Cretaceou  s, 
813*,  817,  826,  828,  829  ;  Tertiary, 
882,  885,  893,  902 ;  igneous  erup- 
tions during,  937  ;  Glacial,  945 

New  Eed  sandstone,  400,  623,  697, 
740 

New  Eiver,  200 

New  York,  mean  height  of  state, 
23 ;  iron  ore  beds,  127,  826,  449*, 
450  ;  lead  mines,  542 ;  marbles, 
524  ;  sulphur  springs,  554 

New  York  Bay,  211*,  224,  225,  230, 
444,592 

New  Zealand,  22,  36,  37,  221 ;  vol- 
canoes of,  296;  connection  with 
Australia,  737,  798,  1019  ;  geysers 
of,  82, 305 ;  glaciers  of,  242  ;  Upper 
Silurian  in,  564 ;  Triassic,  698,  737, 
770;  Jurassic,  776;  Cretaceous, 
857  (coal);  Tertiary,  923,  937; 
Quaternary,  1019 

—  chain  of  islands,  37,  39,  374 
Newark  group,  740 
Newberria  Condoni,  579 
Newburg,  357 

Newcastle  coal,  401 

Newfoundland,  17,  41,  48,  232,  252, 
389,  424,  461,  536,  537,  552,  634 
(coal-beds),  737,  793,  944,  948 
(fiords);  Archaean  in,  443,  444, 
446,  447;  Paleozoic,  461;  Cam- 
brian, 464,  465,  466,  467,  473,  475, 
476,  496;  Calciferous,  492,  496, 
500,  501 ;  Chazy,  503  ;  Upper  Sil- 
urian, 536,  571;  Carbonic,  633, 
635  ;  Glacial,  944,  948 

—  Banks,  882 
Niagara  period,  538 

Niagara  Eiver  and  Falls,  539,  540* 
(section),  542,  553,  580  ;  obstructed 
by  drift,  972*  ;  age  of,  1023 

Nicaragua,  Carboniferous  in,  659 

Nickel,  70,  342 

Nicola  Lake,  746 

Niger  Eiver,  30 

Niihau.  37 

Nile,  30,  172,  173  (slope),  177 
(floods),  190  (silt),  417 

Nileus,  503  ;  affinis,  573  ;  armadillo, 
573  ;  rnacrops,  573  ;  scrutatus,  573 

Nimravus,  918 

Ninafou  eruption,  374 

Nineveh  coal-bed,  651 

Niobium,  449 

Niobrara  group,  815,  825 

—  Eiver,  886 
Nipa,  921 
Niso,  916 

Nitrates,  63§,  137,  138,  191 
Nitric  acid,  63,  124 
Nitrification,  137§ 


Nitrogen,  61,  118,  186,  153;  from 
volcanoes,  293 

Nitrous  acid,  124,  137 

Nitschea  curvula,  699 

Nobby  Island,  N.  S.  W.,  trap  dike 
of,  313 

Nodosaria  Texana,  837 ;  vulgaris 
432* 

Nodules,  73§  (phosphatic),  97 

Norfolk  and  Suffolk  cliffs,  219 

Norian,  446 

None  (Upper),  757 

Normandy,  518 

Normanskill  Graptolites,  516 ; 
shales,  515 

North  Cape,  521 

North  Carolina,  85,  231,  358,  946; 
mean  height  of,  23 ;  coast,  224* ; 
iron  ores,  449 

Norway,  19,  33,  41,  85,  87  ;  snow- 
line  in,  234;  Archjean  in,  453; 
Cambrian,  482,  518 ;  Lower  Silu- 
rian, 518;  Upper  Silurian,  568, 
568,  569 

Norwich  Crag,  927 

Noryte,  86§,  87,  532 

Nostoc  calidarium,  60 

Notharctus,  918 

Nothodon,  688 

Nothosaurus,  773§ 

Notidanus  primigenius,  416*,  901* 

Notochord,  414§ 

Notornis,  1014 

Nototherium  Mitchelli,  1006 

Nova  Scotia,  41 ;  subsidence,  350  ; 
coal-beds,  634,  639 ;  uplifts,  527, 
538,  630 

— ,  Archaean  in,  444;  Cambrian, 
466;  Lower  Silurian  (close  of), 
527,  533;  Upper  Silurian,  537, 
541,  558,  563,  573 ;  Devonian,  578, 
593  ;  Subcarboniferous,  639  ;  Car- 
boniferous, 653,  654*;  Permian, 
658,  660,  708 ;  Triassic,  740  ;  post- 
Paleozoic  upturnings  in,  732 

Nova  Zembla,  48,  776 

Novaculite,  80§ 

Nucleocrinus,  597  ;  Verneuili,  585*,. 
590 

Nucleospira  concinna,  592;  pisi- 
formis,  551 ;  pisum,  567 

Nucula,  525,  602,  621,  757,  780,  792  ; 
lirata,  601 ;  nasuta,  647 ;  per- 
crassa,  854;  Shaleri,  917;  Shu- 
mardana,  647 ;  tenuis,  984 

Nuculana  bellistriata,  690 

Nuculites,  621 

Nudibranchs,  424§ 

Nullipores,  72,  140,  147,  156,  437 

Nummulites,  433§,  896;  Eocene, 
347,>20,  922* 

Nummulites  levigatus,  926;  num- 
mularius,  432*, -922*;  radiatus, 
926 ;  variolarius,  926 

Nummulitic  epoch,  880§ ;  upturn- 
ing at  close  of,  932,  936 

Numuku,  150 

Nunataks,  240§.  241*,  249*  ;  plants, 
of,  945 

Nunda  group,  605 

Nyctilestes,  918 

Nyssa,  896,  921 ;  lanceolata,  889 


1070 


INDEX. 


Oahu,  150,  163,  179,  271*,  282 ;  map 

of,  292 

Obi-Irtish  Kiver,  30 
Obolella,  425§,  481,  486,  496 ;  crassa, 

471* ;  plicata,  520 ;  polita,  478* 
Obolus,    72,    73    (composition    of 

shell),  425§,  482,  521 ;  Apollinis, 

427*  ;  Davidsoni,  567  ;  Labradori- 

cus,  480 
Obsidian,  64,  84§ 

—  Cliff,  264*,  276,337* 
Occident,  21,  22 

Ocean,  abyssal  depths  of,  229 ; 
amount  of  salts  in,  120,  121 ;  sili- 
cates made  at  the  bottom,  186; 
the  great  mineral  spring,  120, 
320 

«—  as  a  mechanical  agent,  209  ;  earth- 
quake waves,  213 ;  abyssal  work, 
229 

Oceanic  currents,  42,  43,  46* 

—  era,  440 ;  islands,  20,  22,  23 ;  life 
not  easily  exterminated,  142 

Oceans,  arrangement  of,  17 ;  depth, 

18,  19§,  380 
Ocoee  group,  468 
Octopods,  424 

Oculina  arbuscula,  analysis  of,  72 
Ocydromus  Australis,  1019 
Odontaspis,  863 
Odontidium,  163,  164*,  165 ;  pinnu- 

latum,  894* 
Odontocephalus,  591 
Odontocetus,  927 
Odontopolys  compsorhytis,  916 
Odontopteris,  637,  671.  685, 693,  699 ; 

obtusiloba,  704 ;  Schlotheimi,  670*, 

689 ;  sphenopteroides,  689 
Odontopteryx,  923§ 
(Eningen,  fossils  at,  921,  922,  926 
Oesel  zones,  568 
Ogden,   Utah,   860*,  861  ;    Canon, 

581  ;  quartzyte,  580,  581 
Ogygia,  482,  520,  521 ;  Buchii,  520 
Ohio,  mean  height  of,  23 ;  mineral 

oil  and  gas,  522,  523,  554,  607,  608, 

609 

Ohio  River,  filled  by  drift,  965 
Ohio  shales,  603,  606,  615 
Ohiocrinus,  516 
Oil.     See  Mineral  oil 
Oil-creek  group,  638 
Oil-sand,  607 
Okhotsk  Sea,  927 
Oklahoma,  836;   mean   height  of, 

23 

O"land,  521 
Olcostephanus     Astierianus,    865 ; 

Speetonensis,  865 ;  Traskii,  837 
Oldhamia,     482  ;     antiqua,     481* ; 

radiata,  481* 
Olean  conglomerate,  647 
Olefiant  gas,  528 
Oleic  acid,  124 
Olenellus,  467,  473*,  479,  481,  482 ; 

asaphoides,    473;    Callavei,   481; 

Gilberti,  478,  474* ;  Kjerulfi,  482 ; 

Thompson!,  478* ;  Vennontanus, 

473* 

Olenellus  zone,  464,  482 
Olenoides,  482 ;  Fordi,  473* 
Qlenopsis,  482 


Olenus,   481,    482,    483;  micrurus, 

481* 

Olenus  schists,  482 
Oligobunis,  918 
Oligocarpia,     699,     756;     Gutbieri, 

699  ;  robustior,  749* 
Oligocene,  880§,  886,  918,  920,  921, 

926 
Oligoclase,  64*§  ;  gneiss  and  granite, 

83 

Oligoporus  nobilis,  641*,  646 
Oliva,  922 ;  Mississippiensis,  916 
Olivella,  916 

Olivine.     See  Chrysolite 
Omnivores,  930 
Omosaurus  armatus,  787 
Omphacyte,  88§ 

Omphyma,  567  ;  turbinata,  564*,  567 
Onchidium,  424§ 
Onchus,  546,  565,  626 ;  Clintoni,  546, 

550 ;  Deweyi,  550 ;   tenuistriatus, 

566* 
Oncoceras,     551,    561  ;    gibbosum, 

549 ;  ovoides,  558,  562 
Oneida  conglomerate,  538 
Oneonta  sandstone,  603,   606,  612, 

618,  621 

Oniscia  harpuia,  916 
Oniscus,  509,  783 
Onoclea  sensibilis,  840,  922 
Onondaga  beds,   sections   of,  552, 

553* 

—  Lake,  553 

—  limestone,  576,  581 

—  period,  408,  410,  535,  552-558, 570, 
572 

—  salt  group,  552 
Ontarian,  446 

Ontario,  salt  group  in,  552 
Ontario  (Lake),  200,  201*,  494,  533, 

946,  947  (depth) 

Onychodus,  417 ;  sigmoides,  589* 
Onyx,  133 

Oolitic,  82  ;  limestones,  79 
Oolyte,  79§,  96§ 

—  ,Bath,  775,  777,  790;  Corallian, 
790;   Great,  775,  777,  779,  790; 
Oxford,  775,  790 

Oolytic  epoch,  738,  775 
Opal,  62§,  64§,  135 
Operculates,  54 
Ophiacodon  grandis,  688 
Ophiderpeton,  706;  Brownriggii,  704 
Ophileta,  495,  499*,  515,  520 ;  com- 

pacta,  500,  520 ;  complanata,  499* ; 

levata,  499* ;  Owenana,  514 ;  pri- 

mordialis,  478* ;  uniangulata,  499* 
Ophiolyte,  79,  89§ 
Ophiurans,  55 
Ophiuroids,  429§,  505*,  646 
Ophyte,  86§ 

Opossum,  415,  902,  910,  924,  926 
Oppelia,  794 
Oquirrh  Mts.,  340,  469 
Oracanthus  Milled,  702 
Oracodon  conulus,  853* 
Orang-outang,  54 
Orange,    N.J.,    columnar    basalt, 

262* 
-  Bay,  858 

—  sand  group,  891,  965 
Orbicula,  482     ^-'' 


Orbicular  dioryte,  87§,  97* 
Orbiculoidea,    514,   612;    Lodensis, 

612*,  620;  minuta,  592,  602;   ru- 

gata,    567;    tenuilamellata,    562; 

Vanuxemi,  557 
Orbitoides,  433§,  896 ;  Mantelli,  896, 

898* 

Orbitoides  limestone,  896 
Orbitolites,  433§ 
Orbitulina  conoidea,  865 ;  discoidea, 

865, 

Orbitulites  Texanus,  834*,  836 
Orbulina  universa,  432* 
Orca,  144 
Orchestia,  420* 
Orchids,  435 
Ordovician,  489 
Ore,  ores,  327,  845,  810 ;  origin  of, 

342,  348 
Oregon,   23,  25;    glaciers  of,   240; 

igneous  action  in,  265,  266,  280  ; 

volcanoes    of,    296;     Cretaceous 

in,  818,  830;  Tertiary,  882,  885, 

892;    John    Day  beds    of,    911; 

sandstone  veins,  344 
Oreodon,  907,  918  ;  gracilis,  910* 
Oreodon  beds,  886,  894,  910,  918 
Oreodoxites  plicatus,  889 
Oreti  series,  770 
Organic  acids,  665 

—  contributions     to    rock-making. 
See  Kocks,  organic  constituents 
of 

—  nature,  essential  elements  of,  9, 
413 

—  remains,  71§ 
Orient,  21,  22 
Orinoco  Kiver,  30,  456 
Oriskany  period,  577 

—  sandstone,  577,  578 
Orizaba  (Mt.),  height  of,  937 
Ormoceras,  501 ;  crepriseptum,  516  ; 

tenuifilum,  514 
Ormoxylon  Erianum,  622 
Ornithomimus,    847,    856 ;     velox, 

847* 

Ornithopoda,  761,  764,  786,  845,  863 
Ornithorhynchus,  415,  795 
Ornithostoma,  863 
Orodus,  644,  692,  702 ;  mammillaris, 

644*,  647 
Orogenic  work,  345,  376§,  391 

—  movements,   Tertiary,   of  Long 
Island   and    Martha's   Vineyard, 
1021*.      See    further,   Mountain- 
making 

Orohippus,  905,  912,  913*,  918; 
agilis,  905* 

Oromeryx,  918 

Orthacanthus,  687 ;  arcuatus,  692 

Orthaulax  Gabbi,  899*,  917 ;  pugnax, 
916 

Orthaulax  bed,  89,1 

Orthids,  719  (time  range) ;  Upper 
Silurian,  574 

Orthis,  310,  425§,  426§,  481, 482, 516, 
517,  521,  550,  561,  562,  568,  579, 
622,  642,  705  (last  in  Permian), 
707 ;  acuminata,  503 ;  arcuata,  625 ; 
biforata,  507*,  514,  520,  550 ;  Bil- 
lings!, 475*;  biloba,  548*,  551; 
borealis,  503;  Bouchardi,  520; 


INDEX. 


1071 


-calligramma,  520,  522,  567;  cos- 
talis,  502*;  Davidsoni,  568;  dis- 
cus, 563;  disparilis,  503,  514; 
elegantula,  519*,  520,  551,  552, 562, 
563,  567,  568,  569;  flabellulum, 
519*,  520;  grandaeva,  499*,  500; 
granulosa,  625 ;  Highlandensis, 
471*  ;  hipparionyx,  579  ;  hybrida, 
551,  563;  imperator,  503;  im- 
pressa,  592,  620,  621 ;  inaequalis, 
602;  interlineata,  626;  lowensis, 
602 ;  lata,  567 ;  lunata,  567 ;  lynx, 
521;  McFarlani,  592;  Michelini, 
703  ;  Michelini  var.  Burlingtonen- 

.sis,  642*,  646;  musculosa,  579; 
oblata,  562,  563,  579  ;  occidentals, 
507*,  514;  orbicularis,  567;  pal- 
liata,  568;  parallela,  626;  parva, 
521 ;  Pecosi,  690 ;  perelegans,  563, 
579;  planoconvexa,  562;  platys, 

.503;  plicata,  626;  porcata,  520; 
Porcia,  503;  prava,  602;  puncto- 

.striata,   563;    Salemensis,    471*; 

.  striatula,  426*,  520,  625,  626,  628  ; 
subaequata,  503  ;  subcarinata,  563 ; 
suborbicularis,  602 ;  subquadrata, 
514 ;  testudinaria,  507*,  514,  521 ; 
Tioga,  621 ;  tricenaria,  507*,  514 ; 
tubulostriata,  563 ;  Tulliensis, 
592 ;  Vanuxemi,  591,  602 ;  varica, 
560*,  562 

•  Orthis  family.     See  Orthids 
Orthisina,    425§,     481;     festinata, 

471*;  orientalis,  471*;  Shumar- 
dana,  685 

Orthoceras,  78,  481,  488,  499,  508, 
511,  515,  516,  517,  520,  521,  546, 
549,  551,  561,  562,  567,  568,  586, 
591,  599,  613,  614,  625,  626,  642, 
675,  705,  707,  719,  727,  736,  756; 
Allumettense,  503;  amplicamera- 
tum,  516 ;  anellum,  514 ;  annula- 
tum,  520,  551, 567, 568, 569  ;  arcuo- 
liratum,  520;  Barrandii,  520; 
bebryx,  620 ;  Blakei,  757 ;  bulla- 
tum,  567,  573  ;  coralliferum,  516 ; 
crotalum,  602  ;  desideratum,  546 ; 
diffidens,  503;  explorator,  503; 
fulgidum,  620;  furtivum,  503; 
ibex,  568,  573 ;  interruptum,  627 ; 
junceum,  506,  508*,  514;  laquea- 
tum,  500*  ;  Ludense,  567  ;  Luthei, 
501;  Midas,  568;  moniliforme, 
524;  multiseptum,  549;  nobile, 
642;  olorus,  508*,  514;  Ozar- 
kense,  500 ;  pacator,  620,  621 ; 
primigenium,  499*,  500, 501,  517* ; 
rectiannulatum,  503 ;  rectum, 
551 ;  strix,  551  ;  subflexuosum, 
627 ;  subulatum,  602,  620  ;  tenui- 
annulatum,  567 ;  tenuiseptum, 
503  ;  transversum,  516  ;  vagans, 
520  ;  velox,  503  ;  virgatum,  569 

•  Orthocerata,  310,  497,  522,  561,  578, 

700 

Orthoceratite  limestone,  627 
Orthoclase,  64*§  ;  augite,  84 
Orthodesma,  516;  parallelum,  511* 
Ortholyte,  83§ 

•  Orthonota,   602,   621 ;    affinis,  567 ; 

angulifera,  567  ;  curta,  551 ;  un- 
dulata,  598*,  602 


Orthophyric  rocks,  77§,  84 

Orthopteroids,  721,  722;  Carbonic, 
722  (culmination) ;  Carboniferous, 
677,  679*,  691 ;  Coal-measure,  701, 
702* 

Orthopters,  419,  574,  600,  702, 
771,  794;  number  of  Florissant, 
900 

Orthothetes  Chemungensis,  591, 
592  ;  crenistria,  700*  ;  subplanus, 
563 ;  umbraculus,  704 ;  Wool- 
worthanus,  563 

Orthrocene,  880§ 

Orycteropus,  54 

Oryctoblattina,  691 

Osage  group,  634,  637 

Osars,  972 

Oscillatoria,  60 

Oshima  (Mt.),  280 

Osmeroides,  862  ;  Lewesiensis,  862* 

Osmunda  affinis,  839  ;  spicant,  74 

Osteolepis,  417,  621,  627 

Ostracoids  (Ostracodes),  421§ ;  Cam- 
brian, 474*,  481,  486,  487 

Ostrea,  780,  828,  829,  840,  854,  864, 
916  ;  acuminata,  790 ;  aquila,  865 ; 
belliplicata,  854 ;  bellovacina,  925 ; 
biauriculata,  866 ;  carinata,  837  ; 
compressirostra,  897*,  915;  con- 
gesta,  841*,  854, 855 ;  Couloni,  865 ; 
crassissima,  926 ;  decussata,  866 ; 
deltoidea,  790  ;  diluviana,  866 ;  dis- 
parilis, 917  ;  falcata,  854 ;  Frank- 
lini,  &36;  Georgiana,  898*,  916; 
gigas,  927;  glabra,  855;  glandi- 
formis,  854 ;  Johnsoni,  915 ;  larva, 
841*,  854,  855,  866 ;  Liassica,  774, 
790;  macroptera,  865;  Marshii, 
780*;  790,  791 ;  Matheroni,  866 ; 
Merceyi,  866 ;  percrassa,  917 ; 
prae-compressirostra,  915;  Pulas- 
kensis,  915;  quadruplicata,  837; 
sellaeformis,  889,  897*;  solitaria, 
791 ;  Sowerbyi,  790 ;  stringilecula, 
760;  subspatulata,  854;  subtri- 
gonalis,  856 ;  thirsae,  915 ;  titan, 
892;  trigonalis,  916;  vesicularis, 
866 ;  Vicksburgensis,  916 

Ostrea  sellaeformis  beds,  889 

Ostrich,  54,  852,  871,  902 

Otodus,  843,  863;  appendiculatus, 
843*,  854 ;  obliquus,  926 

Otozamites  contiguus,  791 ;  lingui- 
formis,  756*  ;  Macombii,  756 

Otozoum,  753  ;  Moodii,  752* 

Ottawa,  490,  491,  493,  494 

Ottrelite,  315,  819 

Ottrelitic  rocks,  82,  83,  467 

Ouachita  Mts.,  380,  389,  732,  817 

Outcrop,  99*§ 

Ovibos  bombifrons,  999 ;  cavifrons, 
999,  1002  ;  maximus,  1002 ;  mos- 
chatus,  1002 

Ovis,  927 

Owl,  902 

Ox,  54,  907 

Oxfordian  group,  775 

Oxidation,  122,  123;  constructive 
effects,  127;  destructive  effects, 
125 

Oxyaena,  918 

Oxyclaenus,  917 


Oxygen,  61  §,  122 ;  in  atmosphere  of 

the  Lithic  era,  440 
Oxyrhina,  144,  843,   863;   hastalis, 

917;  Mantelli,  843* 
Oxyria,  240  ;  digyna,  945 
Oyster  family,  840 
Oysters,  56;  analysis  of  shell,  72 
Ozark  series  of  Broadhead,  468 

Pachysena,  918 

Pachycardium  Spillmani,  855 

Pachyderms,  927 

Pachydiscus  Brazoensis,  836;  per- 
amplus,  866 ;  Whitneyi,  837 

Pachynolophus,  918 

Pachyrhizodus,  843 

Pachytheca,  564 

Paciculus,  918 

Pacific  border  of  America,  18,  24 ; 
volcanoes  of,  295,  296,  297,  987; 
glaciers  of,  945 ;  submerged  river 
channels,  949 ;  Triassic  and  Jur- 
assic of,  746,  756,  808 ;  Cretaceous, 
S18 ;  Tertiary,  885 ;  lacustrine  de- 
posits of,  893 

Pacific  Ocean,  17,  19,  20,  31,  41,  42, 
43;  temperature  of,  49; -salinity 
of,  121 

— ,  island-chains  of,  35-39*,  40,  295, 
296,  393,  395 

— ,  islands  of,  17,  20,  23  (number), 
38,  39,  151,  161,  182,  227 ;  eleva- 
tions in,  350 

— ,  system  of  currents,  43,  44 

— ,  volcanoes  in,  295,  296,  297,  938 

Pah-Ute  Lake,  895;  Kange,  366, 
812 

Pahoehoe,  287§,  288 

Pahranagat  Eange,  366*,  606 

Painted  Canon,  758 

Palaeacis,  639;  cuneiformis,  646; 
obtusus,  646 

Palaeacodon,  918 

Palaeanatina,  621 

Palaearca,  481,  520 

Palaeaspis  Americana,  557* 

Palaeaster,  481,  516, 520 ;  Dyeri,  511 ; 
Jamesi,  510*,  511 ;  magnificua, 
511 ;  matutinus,  505*,  514 ;  Nia- 
garensis,  429*,  551 

Palaeasterina  primaeva,  567 

Palasechinus,  567 

Palaeichthyes,  415§ 

Palaeinachus,  782 

Palselodi,  923 

Palaemon,  703 

Palseoblattina  DonviUei,  566 

Palaeocampa,  723  ;  anthrax,  676,  691 

Palseocaris  typus,  678*,  691 

Palseocastor  Nebrascensis,  911 

Palaeocreusia,  591 ;  Devonica,  587 

Palaeocrinus,  514;  striatus,  502*, 
508 

Palaeoctonus  Appalachians,  754 

Palaeocyclus,  567 ;  rotuloides,  545*, 
550 

Palaeocystites  Chapmani,  508 ;  Daw- 
soni,  503 ;  pulcher,  503 ;  tenuira- 
diatus,  503 

Palaeogene,  880§ 

Palseohatteria,  706,  707,  795,  797; 
longicaudata,  706* 


1072 


INDEX. 


Palaeolagus,  918,  919 
Palaeolithic  Man,  1011 
Palaeomanon,  550 
Palseomyrmex  prodromus,  788 
Palaeoneilo,  621 ;  fllosa,  620 
Palaeonictis,  918,  925 
Palseoniscidae,  620 
Palaeoniscoids,  417§ 
Pateoniscus,  417,  603,  702,  705,  772  ; 

antipodeus,    699  ;    Bainei,    770  ; 

Browni,     692 ;     comptus,     707 ; 

Devonicus,    620  ;    elegans,    707 ; 

Freieslebeni,  417*,  705*,  707,  740  ; 

gracilis,      692;      Jacksoni,    692; 

Leidyanus,  692 ;  lepidurus,  417* ; 

peltigerus,    692;    sculp tus,   770; 

scutigerus,  692 
Palaeopalaemon,    620  ;    Newberryi, 

615* 
Palaeophis  toliapicus,  925 ;  typhaeus, 

923,  926 

Palaeophonus  nuncius,  565 
Palaeopteris  Rcemeriana,  704 
Palaeornis,  864 
Palaeosaccus  Dawsoni,  497 
Palaeosaurus,  773 ;  Fraserianus,  754 
Palaeoscincus,  856 
Palaeospondylus  Gunni,  1031 
Palaeosyops,  907,  918 ;   paludosus, 

907* 
Palaeotherium,  926;  crassum,  926; 

curtum,  924,  926 ;  magnum,  924, 

926  ;    medium,  926  ;    minimum, 

926 ;  minus,  926 
Palseothrissum  Freieslebeni,  740 
Palapteryx,  54,  1014 
Palawan,  40 
Paleocene,  880§ 
Paleothere,  924§ 
Paleozoic,  407 

—  time,  460  ;   growth  of  American 
continent  during,  714 ;  biological 
changes  in,  716;  mountain-mak- 
ing following,  729,  733 

Palinurus,  73 

Palisade  Range,  358,  808 

—  System  of  ranges,  357,  880,  389 

—  Triassic  area,  740,  741,  743,  798, 
799,  800 

Paliurus  zizyphoides,  839 

Pallium,  425§ 

Palmacites,  859 

Palms,  53,  409*  (time  range),  434, 
435,  879 

Palo  Duro  beds,  884,  885,  919 

Paloplotherium  annectens,  926 

Palpipes  priscus,  783* 

Paludina,  152;  fluviorum,  861*, 
864 ;  lenta,  926  ;  orbicularis,  926 

Paludina  limestone,  864 

Paluxy  sands,  817 

Pamlico  Sound,  224* 

Pampas,  24 

Pamunkey  formation,  888 

Panama,  891  (Miocene) ;  conglom- 
erate, 680,  638 

Panamints,  23 

Panchet  group,  698,  769,  778 

Pandanus  family,  777 

Panenka,  621 

Paniselian  beds,  925 

Panochthus,  1004 


Panolax,  919 

Panopsea  Americana,  917  ;  elongata, 

915;    porrectoides,  916;   reflexa, 

917 
Panther    Creek    anthracite    basin, 

section  of,  649* 
Pantolambda,  917 

Pantolestes,  918 ;  brachystomus,  906 
Paolia  vetusta,  679* 
Papandayang  (Mt.),  277 
Papaver,  240 
Parabatrachus  Colei,  708 
Paraclases,  113§ 
Paracyclas,  592,  602,  621 ;  elliptica, 

590,  601 ;  proavia,  585*,  590 
Paradoxides,    474,    475,    477,    482 ; 

Bennetti,     475;     Davidis,     481; 

Forchhammeri,  482 ;   Harknessi, 

481 ;  Harlani,  475,  476* ;  Eegina, 

475,  476*,  521;    Solvensis,    481; 

Tessini,  482 
Paradoxides    beds,    467,  481,   482; 

zone,  464 

Paragonite,  84 ;  schist,  84§ 
Paraguay  River,  183 
Paramorphs,  62§,  67,  69,  70 
Paramys,  917,  918 
Paria,  747. 
Parictis,  918 
Paridigitates,  906§ 
Paris,  17,  347,  926 

—  basin,  774,  872,  880,  920,  928 
Parisian  group,  884,  925 
Parma  sandstone,  657 
Parodiceras,  602 
Paromylacris,  691 
Parophite  schist,  84 
Parrots,  54,  923 

Pasceolus,  515 

Passalacodon,  918 

Patagonia,  20,  209,  925 

Patella,  130,  471,  487,  780 

Patellina  Texana,  834*,  836 

Paterina,  480,  486 

Patoot  group  (beds),  831,  840,  872 

Patriofelis,  918 

Patterson  Glacier,  240 

Patula  alternata,  966;  perspectiva, 

966 ;  solitaria,  966 ;   striatella,  966 
Patuxent  River,  889 
Paumotu  Archipelago,  20,  86,  37, 

145,  222,  350 
Paurodon  valens,  767* 
Peace    Creek,    Fla.,  deposits,  890, 

892  (bone  beds) 

—  River,  Brit.  Amer.,  444,  659,  746, 
830 ;  coal  of,  825 

Pearl  sinter,  82§  ;  spar,  540 

Pearlyte,  84§ 

Peat,  74,  81, 153*§,  666 ;  composition 
of,  661,  713 

Pebbles  in  Archaean  rocks,  448,  449 

Pebidian  period,  457 

Peccary,  54 

Pe-chi-li,  198  (gulf),  696  (province) 

Pecopteris,  671,  684,  699,  704,  750, 
756 ;  acuta,  689 ;  arborescens,  654, 
671*,  689,  692,  704;  Browniana, 
831;  Candolleana,  692-693,  705; 
cyathea,  689;  dentata,  693,  705; 
erosa,  689 ;  Germari,  705 ;  lati- 
folia,  705;  Miltoni,  698,  704; 


notata,    689,    693;    oreopteridea,. 

693,     705;     pennaeformis,     705; 

Pluckeneti,    693,    705 ;    preciosa, 

622;    pteroides,    689,    693,    705; 

robustior,  749*;    serrulata,   689; 

unita,  689 
Pecten,    525,    756,    780,    860,   916; 

Alabamiensis,  915 ;  anatipes,  916 ; 

asper,  865,  866;  Burlingtonensis, 

855;    calvus,   791;    ciuctus,    791, 

865;  circularis,   867;   Clintonius, 

917  ;  decennarius,  917  ;  deforrnis, 

757  ;  discites,  774 ;  fibrosus,  790  ; 

Groenlandicus,  983,  984 ;  irradians, 

994;    Islandicus,    983,    984,  995; 

Jeffersonius,  899*,  917  ;  lens,  790  ; 

Madisonius,  917;    Nillsoni,   855; 

nuperus,      916 ;      operculiformis, 

837  ;  Poulsoni,  898*,  916;  quadri- 

costatus,    865 ;    quinquecostatus, 

854  ;  Stantoni,  836 ;  vagans,  790  ; 

Valoniensis,  774,  790;  venustus, 

854 

Pectinated  rhombs,  430§ 
Pectolite,  68 
Pectunculus    arctatus,    916;    quin- 

querugatus,  917  ;  subovatus,  917 
Pegmatyte,  83§ 
Pei  Ho,  198 
Pelagic   and   abyssal  life,  deposits 

from,  143-144,  229 
Pelagite,  71  § 
Pele's  hair,  279§ 
Pelew  Islands,  350 
Pelicans,  923 

Pelion  Lyelli,  682,  683*,  692 
Pelorosaurus  Becklesii,  863 
Peltoceras,  794  ;  athleta,  791 
Peltodus,  692 
Pelycodus,  918 
Pemphix  Sueurii,  771* 
Pen  of  the  Cuttle-fish,  424*§ 
Penarth  beds,  769 
Peneplane,  204§ 
Pennant,  696 
Pennine  chain,  695,  696 
Pennsylvania,  23  (height),  24,  25, 41, 

356,  357,  358,  882,  383,  388,  891, 

399,  405 ;  coal-field,  map  of,  649*  ; 

copper  ores,  .745;  iron  ore  beds, 

127  ;  marbles,  524 
— ,  mineral  gas  and  oil  in,  606,  607, 

609,  664,  730*,  731 ;  yield  of,  608, 

609 
— ,  diagram    showing    the    courses 

and  flexures  of  the  ridges,  729, 

731* 
— ,  rocks,  section  of,  727,  728 ;  Pros- 

ser's  section  of,  594,  606 
— ,  topographical  map  of,  357,  729r 

730*,  731,  798 
Pennsylvania  period,  632 
Penobscot  Bay,  544,  552 
Penokee-Gogebic  range,  446 
Penokee-Marquette  belt,  446,  449r 

454 

Pentacodon,  917 
Pentacrinus,  59,  428*,  719,  758,  778  ; 

asteriscus,   757,   758*,   760;  Bria- 

reus,  778*,   790 ;    caput-medusse, 

428* ;  decorus,  58*  ;  subangularis,, 

79 


INDEX. 


1073 


Pentamerella  arata,  581,  590 

Pentamerids,  574 

Pentameroceras  mirum,  551 

Pentamerus,  425§,  550,  552,  562, 
568;  borealis,  568;  brevirostris, 
569 ;  caudatus,  567 ;  comis,  601 ; 
conchidium,  552,  569 ;  fornicatus, 
563 ;  galeatus,  560*,  562,  563,  567, 
568,  569,  626,  628 ;  globosus,  520 ; 
Knightii,  551,  564*,  565,'  567,  568, 
569;  Isevis,  569;  oblongus,  520, 
545,  546*,  550,  551,  552,  567,  568, 
569 ;  occidental,  551 ;  pseudo- 
galeatus,  560*,  561,  562 ;  uodatus, 
520 ;  Verneuili,  561* 

Pentamerus,  Lower,  535;  Upper,  535 

Pentremites,  430§,  585,  590 

Pentremites,  597,  601,  602,  641; 
Godoni,  640*,  646;  ovalis,  626; 
pyriformis,  640*,  646 

Pentremital  group,  637 

Peoquop  Range,  365 

Peperino,  80§ 

Peralestes,  789* 

Peramus,  789* 

Peraspalax,  789* 

Perch,  812,  879  ;  family,  862,  901 

Perchoerus,  918 

Pericentric  stratification,  99 

Peridot,  67§ 

Peridotyte.  89§ 

Perihelion  and  aphelion,  changes  of, 
254 

Period,  406§ 

Peripatus,  723 

Periptychus,  917 

Perisphinctes,  749,  760  ;  Colfaxi, 
760;  Muhlbachi,  760;  virgulati- 
formis,  760 

Perlyte,  122 

Permian  period,  660,  689,  690; 
foreign,  697,  704 

—  in  India,  etc.,  supposed  to  be 
glacial.  698 ;  emergence  of  Ant- 
arctic land,  737 

Permo-Carboniferous,  635§,  687 

Perna  maxillata,  378  ;  mytiloides, 
790 

Perry  sandstone,  594,  606 

Persia,  plateau  of,  26  ;  Cretaceous 
in,  857  ;  Tertiary  in,  920 

Persian  Gulf,  41 

Perthite,  321 

Peru,  41,  51,  213,  222 ;  volcanoes  of, 
296;  Cretaceous  in,  857,  867; 
Tertiary,  935 

Peruvian  islands,  153 

Petalite,  449 

Petalodonts,  643,  647,  705 

Petalodus,  680,  692;  curtus,  648; 
destructor,  680*,  692 

Petraia,  515,  520,  567  ;  bina,  520, 
567 ;  profunda,  517 

Petricola,  157  ;  centenaria,  917 

Petrifactions,  131,  135,  143 

Petrified  forests,  135 

Petrodus,  692 ;  occidentalis,680*,692 

Petroleum,  522,  555,  661 

Petrosilex,  84§ 

Petschora-land,  776 

Phacoceras,  675 ;  Dumbli,  675,  676*, 
691 


Phacops,  422§,  520,  521,  551,  561, 

568,  570,  579,  586,  591,  599,  626; 

bufo,    599*;     callicephala,    515; 

caudata,    567,    568  ;     Downingii, 

565*,    567,    573  ;     elegans,    568  ; 

fecunda,  568,  570 ;  granulata,  625 ; 

latifrons,  625,   626,   627;  Logani, 

561*  ;  longicaudata,  567 ;  nupera, 

614 ;  rana,  592, 599*,  614 ;  Stokesi, 

567 ;  trisulcata,  550 
Phaenogams,    434-435,     595;    Neo- 

paleozoic,  460 
Phaethonides,  591,  643 ;  occidental, 

614 ;  spinosus,  614 
Phalangidse,  691 
Phaneropleuron,    418,     621,     625; 

curtum,  617*,  619,  621 
Pharella  Dakotensis,  855 
Phascolestes,  789 
Phascolotherium,  789* ;  Bucklandi, 

789* 

Phasma,  677 
Phenacodus,  903,  910,  917,  918,  925 ; 

primaevus,  903* 
Phenocryst,  77§ 
Philippine  Islands,  296  (volcanoes), 

297,  920,  921 
Phillipsasjrea,    718;     gigas,    590; 

Verneuili,  584*,  585,  590 
Phfflipsid,  521,  643,  676,  686,  700; 

Cliftonensis,    691  ;    major,    691  ; 

Missourieusis,  691 ;   scitula,  691 ; 

seminifera,  700* 
Phillipsite,  136,  144 
Phlegethontia,  692 ;  linearis,  682 
Phlegraean  Fields,  volcanic  region 


Phlogopite,  65§ 

Phlyctaenaspis  Acadica,  616*,  618 

Phoberus  caecus,  59 

Phrenicites,  921 

Phrenix  Islands,  20 

Pholadella,  621 

Pholadomya,    759,    780  ;    abrupta, 

917 ;  cuneata,  925 ;  fiducula,  790 ; 

Lincenumi,    855 ;     Marylandica, 

915;  multicostata,  791;  ovulum, 

791 ;  papyracea,  855 
Pholas,    157,    158;   alatoidea,  915; 


Phonolyte,    85§;    columnar,  263*, 

264* ;  solubility,  122 
Phos  Texanus,  916 
Phosgenite,  335 
Phosphates,  63,  69 
Phosphatic    concretions,    78,    493, 

891;  deposits,  153;   fossils,  314, 

487 

—  rock-material,  72-74, 141 
Phosphoric  acid,  69,  72,  73,  74,  75, 

153,  241,  663 

Phosphorite  beds  of  Quercy,  926 
Phosphorus,  62,  63§,  123;  in  mineral 

coal,  663 

Phragmites  Alaskanus,  839 
Phragmoceras,  567 ;  parvum,  551 
Phragmodictya,  646 
Phrynus,  724 

Phthanocoris,  722  ;  occidentalis,  691 
Phthanyte,  82§ 
Phylloceras,  793,  794;  ptychoicum, 

791 


Phyllograptns,  470, 520  ;  Anna,  500 ; 
typus,  498* 

Phyllopods,  421§,  439§;  Cambrian, 
Lower,  474* ;  Cambrian,  Middle, 
476,  477* ;  Chemung,  614,  615*  ; 
Corniferous,  586  ;  Hamilton,  599, 
600* ;  Lower  Silurian,  521 ;  Paleo- 
zoic, 720 ;  Subcarboniferous,  643 

Phyllyte,  80§,  89§ 

Physa,  152 ;  heterostropha,  682 

Physeter,  912,  927 

Physiographic  chart  of  the  world, 
46,  47*,  350 

Physiographic  geology,  14§,  15 

Physospongia,  639,  646 

Phytolitharia,  163,  164* 

Phytopsis  cellulosa,  505 

Pichincha  (Mt.),  26,  296 

Pickwell  Down  beds,  625 

Picotite,  88 

Picryte,  S"8§ 

Pictured  rocks,  94*,  464,  465* 

Piedmont  region,  24,  448 

Pigeons,  54 

Pikermi  beds,  927 

Pike's  Peak,  811,  876 

Pile  worm,  158    . 

Piloceras,  520,  573  ;  Canadense,  501 ; 
Wortheni,  501 

Pilton  beds,  625 

Pilularia  globulifera,  436* 

Pinacoceras  Metternichi,  774;  par- 
ma,  774 

Pine,  435,  436,  667,  668,  777,  859 

Pine  Mountain,  Ky.,  543,  657 

—  River,  746 

Finite,  68§,  318,  320 

Pinites,  704,  777 

Pinna,  129,  760  ;  affinis,  925 ;  decus- 
sata,  866;  expansa,  759*;  Mis- 
souriensis,  647;  Mulleti,  865; 
peracuta,  690 

Pinnularia  aequalis,  164*,  165 ;  bore- 
alis, 164*,  165;  peregrina,  437*, 
894*;  viridis,  164*,  165;  viridula, 
164*,  165 

Pinon  Range,  365,  733 

Pinus,  859,  922;  abies,  74;  suc- 
cinifer,  922 

Pinyte,  84§ 

Pipestone  quartzyte,  468 

Pisolite,  96*§ 

Pisolitic  limestone,  859 

Pit  River,  747,  749,  809 

Pitchstone,  84§ 

Pithecanthropus  erectus,  1036 

Pitt,  Mt.,  296 

Pittsburg  coal-bed,  653 

Placenticeras  Guadalupae,  855 ;  pla- 
centa, 841,  842*,  854,  855 

Placoderms,  417 ;  Trenton,  509 

Placodus,  773 

Placoparia,  520,  521 

Placuna  scabra,  854 

Placunopsis,  690 

Planer  (Lower),  866;  (Middle),  866 

Plagiaulax,  768,  789,  864;  minor, 
789*  ' 

Plagioclase,  64§ 

Plaisancian  beds,  927 

Planation,  167§,  169,  219,  221* 

Plane  tree,  831,  922 


DANA'S  MANUAL  —  68 


1074 


INDEX. 


Planorbis,  152,  856;  discus,  926; 
euomphalus,  926 

Plant-beds,  933 

Plantain,  812 

Plants,  71,  72 ;  geographical  distri- 
bution of,  52-60 ;  phosphoric 
acid  in  ash,  73 ;  analyses  of,  74, 
75 ;  chemical  work  by,  136 ;  pro- 
tective eifects  of,  155;  materials 
for  rock-making,  140,  143 

Plaster  of  Paris,  69§ 

Plastic  clays,  821,  825,  925 

Plasticity  of  rocks  from  superheated 


Plastomenus,  850 

Platanus,  831,  840,  922 ;  aceroides, 
839 ;  Guillelmse,  839  ;  Reynoldsii, 
839 

Plateau,  25§,  188 

—belt,  739,  748,  749,  811 ;  region, 
818 

Plateaus  carved  into  mountains, 
188 

Platephemera  antiqua,  600* 

Platinum,  331,  376,  455 

Platte  River,  29,  885 

Plattendolomit,  697 

Platyceras,  478,  487,  499,  561,  562, 
568,  570,  574,  578,  585,  590,  598, 
602,  612,  642;  angulatum,  548*, 
551 ;  auriformis,  503 ;  carinatum, 
592,  602  ;  conicum,  592,  602  ;  den- 
talium,  592 ;  dumosum,  586*,  590 ; 
equilaterale,  647  ;  erectum,  602  ; 
Haliotis,  573 ;  nodosum,  592  ;  pri- 
maevum,  471,  472* ;  rectum,  602 ; 
reversum,  647 ;  spirale,  579  ;  sym- 
metricum,  602;  thetis,  602;  ven- 
tricosum,  562 ;  vetustuin,  625 

Platycrinus,  597,  646;  Saffordi, 
640*,  646 

Platygnathus,  626 

Platygonus,  919 

Platyschisma  helicites,  567 ;  heli- 
coides,  578 

Platysomus,  705;  gibbosus,  707; 
macrurus,  707 

Platystoraa,  562,  590,  612,  621 ;  Ni- 
agarenese,  548*,  551 

Platystrophia  biforata,  507*,  550 

Playa,  196§ 

Pleasant  (Mt.)  beds,  606 

Plectambonites,  503,  550  ;  sericeus, 
507*,  514,  520,  522,  524,  550; 
transversalis,  426*,  548*,  551,  568 

Plectoceras,  501 

Plectrodus  mirabilis,  567 ;  pleio- 
pristis,  567 

Pleistocene  life,  North  American, 
997  ;  South  American,  1002 ;  Eu- 
ropean, 1004;  Australian,  1006; 
foreign,  1004  ;  man,  1008 

Pleistocene  period,  890,  940,  941 

Plesiadapis,  925 

Plesiosaurus,  773,  785, 790,  856,  863 ; 
dolichodeirus,  784* ;  macrocepha- 
lus,  785* ;  oeciduus,  828,  J356 

Pleuracanthus  Gaudryi,  702,  703* 

Pleuroceras  spinatum,  781* 

Pleuroccelus  altus,  836 ;  nanus,  836* 

Pleurocystites  filitextus,  505*,  514 ; 
tenuiradiatuB,  517 


Pleurodictyon,  626 

Pleurolichus,  918 

Pleuromya,  760 ;  laevigata,  837 ;  uni- 
oides,  760 

Pleurophorus  elongatus,  774;  sub- 
cuneatus,  685* 

Pleurorhynchus,  520 

Pleurosigma  angulatum,  437* 

Pleurotoma,  922;  abundans,  916; 
Americana,  916;  attenuate,  926; 
beadata,  916 ;  congesta,  916 ;  cris- 
tata,  916 ;  declivis,  916 ;  Heilprini, 
916;  Huppertzi,  916;  moniliata, 
915;  perexilis,  916;  rotaedens, 
916 ;  tenella,  916  ;  Texana,  855  ; 
Tippana,  855 

Pleurotomaria,  59,487,  493,499,  516, 
520,  521,  525,  551,  562,  586,  590, 
598,  621,  642,  700,  707,  780  (culmi- 
nation), 792  ;  Adansoniana,  59 ;  an- 
tiquata,  503  ;  Attleborensis,  471 ; 
Austinensis,  837 ;  biangulata,  503  ; 
Brittoni,  854;  calcifera,  500;  ca- 
lyx, 503  ;  carbonaria,  690 ;  docens, 
503 ;  Grayvillensis,  690  ;  grega- 
ria,  500;  litorea,  544*,  549;  Ohio- 
ensis,  516 ;  pervetusta,  549 ;  Shu- 
mardi,  647 ;  solarioides,  549,  551 ; 
sphaerulata,  675*,  690;  staminea, 
517 ;  subconica,  514 ;  tabulata, 
675*,  690;  turbinea,  627;  virgu- 
lata,  602 

Pliauchenia,  912,  919 

Plicated  rocks,  effects  of  erosion  of, 
186* 

Plication  of  clayey  layers,  208,  209* 

Plications  and  plicating,  experi- 
ments by  Daubree  on,  353;  in 
mountains,  354 

Plicatula  inflata,  866 ;  placunea,  837, 
865 ;  spinosa,  790 

Plinthosella  squamosa,  432* 

Pliocene  period,  880§ 

Pliohippus,  913*,  919 

Pliohippus  beds,  885 

Pliopithecus,  927 

Pliosaurus,  785 

Plocoscyphia  maeandrina,  866 

Plombieres,  formation  of  zeolites 
at,  323 

Plover,  902 

Plum,  921 

Plumbaginous  rock.    See  Graphitic 

Plumbago,  62§ 

Plutonic  rocks,  298§ 

Pluvial  period,  981 

Pnesopteryx,  1014 

Po,  ratio  of  sediment  to  water,  190 

Pocono  group,  410,  634,  636,  728 

Podosthenic,  439,  717§,  726,  796 

Podozamites  Emmonsi,  749* ;  lance- 
olatus,  833* ;  nervosus,  834 

Podura,  419,  702 

Poebrotherium,  911,  918 ;  labiatum, 
910,  911* 

Poecilodus,  692 

Pogonip  limestone,  495,  516 

Pogonodon,  918 

Poikilitic  group,  631,  7S8 

Polacanthus  Foxi,  868 

Polar  Bear,  950 

—  ice-cap,  346 


Polenos  Island,  296  (volcanoes) 

Polioptenus  elegans,  704 

Polishing  of  rocks.    See  Scratches 

Pollinices  Burnsii,  917 

Polycystines,  433* 

Polyernus,  691 

Polygnathus  dubius,  621 ;  nasutus, 

621 ;    palmatus,    621 ;    princeps, 

621 ;  punctatus,  621 
Polymastodon,  917 
Polynesian  chain  of  islands,  37*,  38, 

39 

Polyonax,  847 
Polyps,  Polyp  corals,  144, 419, 429*, 

431§ 

Polypterus,  59,  417 
Polyzoans,  427 

Pomeroy  coal-bed,  653,  654,  689 
Pompeii,  280 

Ponderosa  marls.  See  Exogyra  pon- 
der osa  marls 
Ponent  series,  728 
Pontian  stage,  927 
Popanoceras,  686 
Poplar,  837-,  922 

Popocatapetl  (Mt.),  height  of,  937 
Populus   laevigata,    839;   mutabilis 

ovalis,   839;    Nebrascensis,    889 

primseva,  833 
Porambonites,  521 
Porcelain  clay,  81, 184,  638 ;  jasper,, 

84§ 

Porcelanyte,  84§ 
Porcellio,  420* 
Porcupine,  798 
Porcupine  Hills  beds,  830 
Porifera,  431  § 
Poroblattina,  691 
Porocrinus,  514,  516 
Pororoca,  212§,  215 
Porous  rocks,  328 
Porphyritic  rocks,  77*§,  83§,  824 
Porphyry,  84§,  341* 
Porphyryte,  86 
Port  Hudson  clay,  198 
Port  Jackson,  E".  S.  W.,  cliffs  at, 

221* 

Port  Jackson  shark,  643,  797 
Portage  epoch  and  group,  576,  602 

—  sandstone,  603,  605 
Porte  Blanche,  248 

Portheus,  844*,  862;  molossus,  848 
Portland  beds,  England,  788,  777; 
dirt-bed,  775,  776* 

—  cement,  79§ 

Portland  Oolyte,  411, 775 ;  stone,  775 

Portland,  Victoria,  34 

Portlandian  group,  738,  775 

Portsdown  axis,  936 

Portugal,  85;  Cambrian  in,  484; 
Lower  Silurian,  521 

Posidonomya,  756;  Bronni,  790; 
venusta,  627 

Post-Pliocene,  940§,  941 

Post-Tertiary,  940 

Pot-holes,  184,  250,  949 

Potamides  transsectus,  916 

Potash,  61§,  81 ;  salts,  320 

Potassium,  61 

Potentilla,  240 

Poteriocrinus,  532,  646,  690;  Cox- 
anus,  640 


INDEX. 


1075 


Potomac  group,  816 
Potosi,  26 

Potsdam   period,    Potsdam    Sand- 
stone, 463,  464 
Potter's  clay,  81  § 
Pottsville  coal-beds,  650,  656 

—  conglomerate,  64T 
Powder  Eiver,  266 
Pozzuolana,  80§ 
Prsearcturus,  623,  624 
Prasopora  lycoperdon,  505*,  514 
Prawn,  438 

Precession  of  the  equinoxes,  258 
Prehnite,  68 
Preston  beds,  817,  836 
Prestwichia,  701, 720 ;  anthrax,  703 ; 

Danaa,  977*,  691 ;  longispina,  691; 

rotundata,  701*,  703 
Priacodon  ferox,  767* 
Priconodon  crassus,  836* 
Primal  of  Rogers,  490,  728 

—  Sandstone,  463 
Primary,  408§,  880 
Primates.     See  Quadrumana 
Primitia,  481,  516 
Primitive  system,  408§ 
Primitivgebirge,  440 
Primordial,  462,  464,  482 

Prince  Edward  Island,  357,  741; 
Permian  in,  660;  Triassic,  753, 
755 

Prince  Patrick  Island,  749,  760, 
792 

Prince  William  Sound,  240 

Prioniodus  acicularis,  621 ;  angula- 
tus,  621 ;  armatus,  621 ;  erraticus, 
621 ;  spicatus,  621 

Prionocyclus,  855 ;  Woolgari,  855 

Prionotropis,  855 

Pristis  bisulcatus,  925 

Proboscideans,  919 

Procamelus,  911,  919 

Prodryas  Persephone,  900* 

Productella,  611,  612  ;  hirsuta,  621 ; 
lacrymosa,  613*,  621 ;  navicella, 
590;  pyxidata,  602;  speciosa, 
620 ;  subaculeata,  585* ;  subulata, 
598*,  601,  602 ;  truncata,  602 

Productus,  309,  427*,  591,  592,  642, 
674,^700,  705-,  -707  ;  aculeatus,  427* ; 
Cancrini,  704 ;  cora,  690 ;  costatus, 
606,  704;  dissimilis,  602;  Fle- 
mingi,  646;  horridus,  704,  707; 
lacrymosus,  592  ;  latissimus,  704 ; 
Leplayi,  704;  longispinus,  700*, 
704,  711 ;  mesolobus,  606 ;  muri- 
catus,  690;  Nebrascensis,  675*, 
690 ;  Norwood!,  685 ;  parvus,  647  ; 
prselongus,  626  ;  punctatus,  642*, 
690,  704;  Rogersi,  685;  scabri- 
culus,  703,  704;  scitulus,  646; 
semireticulatus,  427*,  685,  690, 
711;  Shumardianus,  602;  spe- 
ciosus,  592 ;  subaculeatus,  626, 
627,  628 

Proetus,  513,  515,  521,  552,  562,  568, 
579, 586, 591,  643,  720 ;  auriculatus, 
614;  crassimarginatus,  587*,  591, 
599  ;  doris,  614  ;  Girvanensis,  520  ; 
latifrons,  565*,  567  ;  minutus,  614 ; 
parviusculus,  516 ;  precursor, 
€14  ;  Stokesi,  551,  567,  569 


Proganochelys  Quenstedtii,  773 

Progonoblattina,  691 

Progress   in  earth's  development, 

397 

Proicene,  880§ 
Prolecanites  Lyoni,  643* 
Promontory  Eange,  365 
Promylacris,  691 
Propylyte,  87§,  304 
Prorhynchus,  621 ;  nasutum,  621 
Proscorpius  Osborni,  557* 
Prosoponiscus  problematicus,  707 
Prospect  Ridges,  495,  733 
Prosqualodon,  927 
Prosthenic,  717§,  796,  870 
Protseiphyllum,  831 
Protannularia  Harknessi,  519* 
Protapirus,  910,  918 
Protaster,  516,  562 ;  Forbesii,  562 ; 

hirudo,  567 ;  Sedgwickii,  567 
Protaxis,    24§.    See    also    Acadian 

protaxis ;  Appalachian  ;  Archaean  ; 

Rocky     Mountain ;     also     Gold 

Range 

Proteacese,  921,  922 
Protean  group,  542,  638 
Proterosaurus  Speneri,  706* 
Protichnites  septemnotatus,  478* 
Protoadapis,  925 

Protobalanus  Hamiltonensis,  600* 
Protocardium  Hillamim,  836 
Protocarids,  486 
Protocaris,  720 ;  Marshi,  474* 
Protoceras,  911,  918 
Protoceras  beds,  886,  894,  911,  918 
Protocimex  Siluricus,  520 
Protococcus,  235,  436 ;  nivalis,  241, 

436$ 

Protogine,s83§ 
Protogonia,  917 
Protogonodon,  917 
Protohippus,  911,  912,  913*,  919 
Protolabis,  911,  919 
Protolimulus  Eriensis,  615*,  617 
Protolycosa  anthracophila,  703 
Protophasmids,  677,  679,  691,  701 
Protophytes,     407 ;      Corniferous, 

583* ;  Cretaceous,  859  ;  Tertiary, 

895 

Protopterus,  60 
Protoreodon,  907,  918 
Protorthis  Billingsi,  475* 
ProtosaMnia,  718 ;  Huronensis,  584 
Protospongia,  482,  497;    coronata, 

498*;    cyathiformis,  498*;    fene- 

strata,    474*,    481 ;    mononema, 

498*,    500;    Quebecensis,    498*; 

tetranema,  498* 
Protostega  gigas,  849 
Prototarites  Logani,  591 
Prototherium,  795,  927 
Prototype  characters,  928 
Protozoans,  140,  141,  407,  409*,  418, 

419,    431,    432*;    Archaean,    455; 

Lower  Cambrian,  470 
Protozoic,  407§ 
Provence,  Cretaceous  in,  866 
Proviverra,  918,  925 
Provo,  360*,  361 
Psammodonts,  643§,  647 
Psammodus,  589,  643 
Psaronius,  704 ;  Erianus,  595 


Pseudaelurus,  919 

Pseudodiadema,  779,    834;    diatre- 

tum,  854 ;    hemisphaericum,  790  ; 

Moorei,   790;  seriale,  778*,   779; 

Texanum,  836 
Pseudoliva,  916;   scalina,  915;  tu- 

berculifera,  915 ;  unicarinata,  915 
Pseudomonotis,  690 ;  Hawni,  685*  ; 

Ochotica,  758 ;  speluncaria,  707 
Pseudopecopteris,  699  ;  anceps,  645, 

689;  decipiens,   689;  irregularis, 

689  ;  latifolia,  689  ;  muricata,  689 ; 

nervosa,  689 ;  nummularia,  689 
Psilomelane,  71§ 
Psilophyton,  583,  590;  cornutum, 

560  ;  princeps,  583*,  622 
Psittacotherium,  904,  917 
Pteranodon,  863 ;  ingens,  852 ;  lon- 

giceps,  849*,  852 
Pteranodonts,  851 
Pteraspids,  417,  557,  725 
Pteraspis,  564,  625 ;  Banksii,  566*, 

567 ;  Ludensis,  567 ;  truncata,  567 
Pterichthys,     566,    617,    625,    627 ; 

Canadensis,  611 ;  cornutus,  624* ; 

major,  627 ;  Milleri,  624* 
Pterinea,  621,  877  (end)  ;  Chemun- 

gensis,  613*,  621;  flabella,  598*, 

602  ;  hians,  567 ;  retroflexa,  567, 

568;     Sowerbyi,    567;    sublaevis, 

567 ;  Trentonensis,  507* 
Pteris  aquilina,  74  ;  erosa,  839 
Pterocerajucarinata,   865 ;    oceani, 

791 ;  ponti,  791 
Pterocerian  beds,  791 
Pterodactyls,  796 ;  Jurassic,  776 
Pterodactylus,  788,  790;   crassiros- 

tris,  786*,  788 ;  montanus,  767 
Pterodon,  918 
PterophyUum,   698;    Jaegeri,   770*, 

774 ;  Riegeri,  749* 
Pteropods,   59,   72,  141,   144,  423§, 

424§,  425*  ;  Cambrian,  469,  472*, 

475*,  478*,  480,  483 
Pteropsis  Conradi,  897*;  lapidosa, 

916 

Pteropus,  53 
Pterosaurs,     796,    877 ;     Jurassic, 

760,  767,  787*,  788;  Cretaceous, 

844,   851,   852,  863,  870,  871,  876 

(end  of  tribe) 

Pterotheca,  503,  506 ;  attenuata,  514 
Pterygotus,     557,     565,    722,    724; 

acuticaudatus,     557  4     Anglicus, 

623* ;  bilobus,  564*,  567 
Ptilodictya,  514,  521,  550;  scalpel- 

lum,  567' 
Ptilodus,  917 
Ptilophyton  plumula,   645  (last  of 

the  genus) 

Ptychaspis  speciosa,  501 
Ptychites,  686 ;  gibbosus,  774 
Ptychoceras,  855 ;  Texanum,  855 
Ptychodus  mammillaris,  855;  Mor- 

toni,  843* 
Ptychoparia,     500,    516;    Adamsi, 

473*;    Calcifera,    501;    formosa, 

476*  ;    Hartti,  501 ;  Kingi,  476* ; 

Matthewi,  476*  ;  minuta,  479* 
Ptychopteria,  621,  638 ;  falcata,  621 ; 

Sao,  621 
Ptyonius  serrula,  682,  683* 


1076 


INDEX. 


Ptyonodus,  687 
Pudding-granite,  97§ 
Pudding-stone,  80§,  147 
Puerco  Eocene  lake  or  basin,  881*, 
882,  893 

—  group,  886 
Puerto  Eico,  19 
Puget  group,  831 

—  Sound,  831 
Pugnellus  densatus,  854 
Pulaski  shales,  494 
Pullastra  arenicola,  774 
Pulmonates,  423,  674  (first),  676* 
Pumice,  80,  84§,  136,  144,  266,  276, 

892 

Punjab,  770 

Pupa,  152,  708 ;  Blandi,  966 ;  con- 
tracta,  966;  fallax,  966;  mus- 
corum,  966 ;  quarticaria,  966 ; 
simplex,  966 ;  Vermilionensis, 
676*,  690 ;  vetusta,  676*,  682,  690 

Purbeck  axis,  936 

—  beds,  Purbeckian,  411,  775,  777, 
783,  789,  791 

Purity  of  air    and    waters  in  the 

Cambrian,  484,  485 
Purpura,  130  ;  cancellata,  855 
Purus,  867 

Putnam  County,  N.Y.,  24 
Pycnodonts,  417§,  836 
Pycnodus,  417,  772,  783 
Pycnogonids,  419 
Pygidium,  421  § 
Pygocephalus  Couperi,  703 
Pygopterus,  692, 705  ;  mandibularis, 

707 

Pygurus  rostratus,  865 
Pyramids  of  Egypt,  made  in  part  of 

Nummulitic  limestone,  920 
Pyrazisinus  acutus,  916  ;  campanu- 

latus,  898*,  916 
Pyrenean  basin,  857 
Pyrenees,  23,  239,  265,  812 ;  Lower 

Silurian  in,  518  ;   Jurassic,   775 ; 

Cretaceous,   866;    Tertiary,  347, 

865,  919,  920 ;    elevation  of,  932, 

936 
Pyrifusus    granosus,    855;     New- 

berryi,    841*,    855;    subduratus, 

854 

Pyrite,  70*§,  123 
Pyrites,  80 

Pyritiferous  rocks,  78§,  84,  658 
Pyromeride,  84§ 
Pyrophyllite,  68§,  89 
Pyrophyllyte  schist,  89§ 
Pyroxene,  67*§,  85,  86, 288* ;  rocks, 


Pyroxenyte,  88§,  532 
Pyrrhotite,  70§ 
Pytho,  847 
Pythonomorphs,  826,  847 

Quadersandstein,  Upper,  866 
Quadrumana,  54,  902,  903,  906,  907, 

917  ;  in  Europe,  923,  925,  927 
Quadrupeds.    See  Mammals 
Quakertown  coal-beds,  656 
Quartz,  15,  62,  63§ ;  work  of  solu- 
tions of,  135-136 

Quartz-andesyte,     86§,    273,    296; 
basalt,    296;     dioryte,   86§,  272; 


doleryte,  87§  ;    felsyte,  272,  325; 

gabbro,  87§ ;   porphyry,  84§,  817 ; 

syenyte,  85§ ;    trachyte,  84§,  86, 

273,  314  (see  also  Ehyolyte) 
Quartz  flour  from  glaciers,  169 
Quartzophyric  rocks,  77§,  83,  84 
Quartzose  rocks,  78§ 
Quartzyte,  80§,  82§,  112*  (jointed) ; 

septaria,  138* 
Quartzytic  rocks,  83,  84 
Quaternary  era,  940  ;  general  obser- 
vations on,  1016 
Quebec,  466 
—  group,   482,  490,    496,    497,  503, 

527* 
Queen  Charlotte  Islands,  747,  757, 

760,  809,  818,  830,  868 
Queensland,  698,  699  ;  Devonian  in, 

628 ;  Jurassic,   776 ;  Cretaceous, 

857 
Quenstedioceras    cordiforme,  758*, 

760 
Quercus,  840,  921, 922 ;  angustiloba, 

839;  castanopsis,  839;  Ellisiana, 

839  ;  Godeti,  839  ;  myrtifblia,  895*, 

896;  suber,  713 
Quercy  phosphorite  beds,  926 
Quetta,  earthquake  in  1892,  375 
Quicklime,  78§,  79 
Quicksilver  mines,  335 
Quito,  plateau,  26;  volcanoes  of,  296 

Eacket  Eiver,  946 

Eacodiscula,  432* 

Eadack  Islands,  36,  38,  39,  145 

Badiates,  419 

Eadiolarian   earth,   935,   936;  ooze, 

144 
Eadiolarians,  57,  64,   72,   121,  136, 

141,  144,  433*  ;  Archaean,  1029 
Eadiolite  limestone,  866 
Kadiolites,  820,  861,  877;    Austin- 

ensis,  855 ;  Bournoni,  861*  ;  Mor- 

toni,    861;    Neocomiensis,    865; 

Texanus,  834,  835*,  836 
Eadula  acutilieneata,  854 
Eafinesquina,  503,  579;  alternata, 

507*,    514,    524;    fasciata,    503; 

incrassata,  503 
Eaft  of  Bed  Eiver,  191 
Eagadinia  annulata,  432* 
Eaibl  shales,  774 
Eain,  causes  influencing  the  amount 

of,  50,  51 

Eain-drop,    work    of,    177§,    178* 
Eain-prints,  95§,  178,  223,  645,  742 
Eain  fall,  51,  944,  945 
Eainier,  Mt.     See  Tacoma 
Eainy  Lake,  446 
Eajmahal  group,  698,  873 
Ealick  Islands,  36,  38,  39,  145 
Eancocas  group,  821 
Eangifer  caribou,  946,  1002 ;  taran- 

dus,  946 

Eanunculus,  240 
Eaphistoma,  506,  520,  521 ;  lenticu- 

lare,  507*,  514,  524,  567;  multi- 

volvatum,  501 ;    Pepinense,  501 ; 

planistrium,  508 
Eappahannock  freestones,  816 
Earitan  beds  (group),  815,  821 
Eat,  58,  156,  797 


Eaton  coal-field,  364 

Eaton  Mts.,  828 

Eattan,  435 

Eattlesnake,  682 

Eauchwacke,  697 

Eauhkalk,  697 

Eauracian  group,  790 

Eays,  415§,  418 

Eazor  stone,  88§ 

Eecent  period,  1012 

Eeceptaculites,  497*,  513,  515,  516, 
560,  584,  597;  elegantulus,  497*, 
500  ;  globularis,  513  ;  infundibuli- 
formis,  562 ;  lowensis,  513  ;  Nep- 
tuni,  517,  524,  569;  Oweni,  513, 
515 

Eed  Bluff  group,  889 

Eed  Crag,  927 

Eed  Deer  Eiver,  847 

Eed  earth,  134 

Eed  marl,  542,  627 

Eed  ocher,  70§,  126,  331 

Eed  porphyry,  86§ 

Eed  Eiver,  191  (raft),  819,  885,  888,. 
895 

Eed  Eiver  of  the  North,  947 

Eed  Sea,  21,  41,  200  ;  volcanoes  of, 
295,  296 

Eed  Wall  Group,  469,  658 

Eedwood,  831,  859,  939 

Eegelation,  245§ 

Eeindeer,  946,  950,  1013 

Eeindeer  or  Mesolithic  epoch,. 
997,  1009 

Eemopleurides,  520,  521 

Eensselferia,  562,  578,  579 ;  ovoides, 
578*,  579 

Eensselaerite,  320,  453§ 

Eeptiles,  54,  55,  414  ;  reign,  or  era 
of,  737  ;  Permian,  687,  706,  726  : 
relation  to  Birds,  794,  795 

Eequienia,  877  (end  of  genus)  ;  am- 
monia, 865;  Lonsdalei,  865;  ob- 
longa,  865;  patagiata,  836;  Texana,. 
834,  835*,  836 

Eesins,  74,  143,  712,  713 

Eespiration,  136§ 

Eeteocrinus,  516 

Eetepora,  427 

Eetzia,  627 

Ehabdoceras  Eusselli,  757 

Ehabdoceras  bed,  757 

Ehacophyllites,  760 

Ehacophyllum,  699  ;  Brownii,  611 ; 
filiciforme,  689,  705  ;  flabellatum, 
645  ;  lactuca,  689,  693,  705 

Ehadinichthys,  692 

Ehaetic  beds^  738,  769 

Ehamnus  Goldianus,  839  ;  rectiner- 
vis,  839  ;  salicifolius,  839 

Ehamphorhynchus,  788,  790 ;  phyl- 
lurus,  787*,  788 

Ehea,  54 

Ehenan  beds,  626,  627 

Ehine,  169,  176,  191  (denudation), 
195  (loess),  570 

Ehinoceros,  54,  902,  907,  909,  910, 
911,  927,  928  ;  Etruscus,  927 : 
hemitoachus,  1005,  1006;  incisi- 
vus,  927  ;  megarhinus,  927 ;  pro- 
terus,  1001 ;  Schleiermacheri,  927; 
tichorhinus,  1004,  1005,  1006 


INDEX. 


1077 


Khizocarps,  435§,  436*,  584,  611, 
718 

Rhizocrinus,  59 

Rhizodus,  417,  692 

Rhizopods,  56,  72,  140,  432*§,  817 ; 
Archaean,  454,  455 

Rhodanian,  859,  865 

Rhode  Island,  mean  height  of,  23 ; 
coal-beds  of,  634 

Rhodocrinus,  597 

Rhone,  slope  of  river,  178;  dis- 
charge of  detritus  by,  190 

—  valley  glaciers,  235*,  238,  242 

Rhotomagian,  859,  866 

Rhus,  921 

Rhynchocephalia,  54,  687,  706,  795, 
856 

Rhynchodus  secans,  589* 

Rhyncholites,  424§ 

\Rhynchonella,  425§,  426*,  516,  517, 
520,  550,  552,  562,  568,  579,  642, 
700,  719,  756,  757 ;  acutirostris, 
503  ;  affinis,  568 ;  altilis,  503 ;  bi- 
dentata,  569;  capax,  507*,  514; 
castanea,  592;  compressa,  865; 
concinna,  790,  791  ;  contracta, 
613*,  621 ;  corallina,  790 ;  cuboides, 
593,  601,  622,  625,  627,  628 ;  Cuvi- 
eri,  866;  decorata,  790;  dubia, 
503 ;  duplicate,  592 ;  eximia,  620 ; 
inconstans,  779  ;  Laura,  592 ;  Mar- 
tini, 866 ;  navicula,  567 ;  neglecta, 
551,  567;  nobilis,  562;  nucula, 
567  ;  oblata,  579  ;  obsoleta,  790  ; 
orientalis,  503 ;  Petrocorriensis, 
866;  pigmaea,  790;  plena,  502*; 
pleurodon,  628;  plicatilis,  866; 
psittacea,  426*,  984 ;  pugnus,  620, 
628;  semiplicata,  562;  sinuata, 
592 ;  socialis,  790 ;  speciosa,  579  ; 
spinosa,  790 ;  Strickland!,  567,  569, 
573 ;  subangulata,  790 ;  tripar- 
tita,  520 ;  variabilis,  791 ;  varians, 
790 ;  ventricosa,  560*,  562 ;  Wil- 
soni,  562,  567,  569,  573 

Rhynchonellids,  922 

Rhynchophora,  number  of  Floris- 
sant, 900 

Rhynchosaurus,  773 

Rhynchotreta  cuneata,  548*,  551, 
569 

Rhyolyte,  84§,  87,  272,  273,  276 

Rhytina  Stelleri,  1015 

Richmond  (Va.)  basin,  358,  742, 756 ; 
coal  areas,  743,  755 ;  infusorial 
earth,  894*,  895;  Triassic  area, 
740,  741,  743,  799 

Ridges,  28* 

Riffelhorn,  248 

Rill-marks,  95*§,  538 

Rimella,  916 ;  laqueata,  916 ;  Tex- 
ana,  916 

Ringgold  and  Rogers  Exploring  Ex- 
pedition, 927 

Ringicula  biplicata,  916 

Rio  de  la  Plata.    See  La  Plata 

Rio  Grande,  817,  819,  855,  885 

Ripley  epoch  or  group,  815,  821, 
840.  854,  873 

Ripple-marks,  13,  89,  94§,  95*,  161, 
223  ;  Cambrian,  464,  484 

Risaoa  Chastelii,  926 


River  systems,  28,  29,  30 

—  valleys,     excavation     of,     178 ; 
buried,  204,  934 

—  waters,  analyses  of,  121 
Rivers :  lengths  and  drainage  areas, 

30,  172,  173 ;  special  points  in 
fluvial  history,  203-204;  trans- 
portation and  deposition  by,  189- 
202 ;  distribution  of  transported 
material,  191 ;  velocity  of,  175" ; 
working-power  of,  173-177 

Roan  Mts.,  901,  946 

Robinia,  921 

Roche-Moutonnee  Creek,  250* 

Roches  moutonnees,  250*§ 

Rock-cities,  604,  647 

Rock-flour,  81§,  248,  251,  941 

Rock-making,  140§ 

Rock  salt,  320,  552,  553,  554,  769 

Rockford  shale,  606 

Rocks  :  constituents,  61 ;  kinds  of, 
75;  organic  constituents,  71-75, 
140-141,  458 ;  structure,  90§ ;  ex- 
pansion, 259 

— ,  volcanic.    See  Volcanic 

Rockwood  beds,  577 

Rocky  Mountain  Chain,  389,  748; 
protaxis,  24,  444,  461,  464,  483, 
490,  746;  silver  and  lead  mines, 
876 

Rocky  Mountain  region,  Archaean 
in,  444;  Cambrian,  464;  Lower 
Silurian,  494,  495;  Upper  Silu- 
rian, 541 ;  Devonian,  575,  581  ; 
Glacial,  944 ;  Subcarboniferous, 
639;  Carboniferous,  634,  635, 
658;  Triassic  and  Jurassic,  808- 
812;  Cretaceous,  814,  815,  818, 
827,  829,  838,  868,  880  ;  Tertiary, 
882,  887;  elevation  during,  933, 
935 

Rocky  Mts.,  24,  31*,  51 ;  glaciers 
of,  240 ;  changes  of  level  in,  347 ; 
making  of  Laramide  Mts.,  874; 
volcanoes  of,  296,  937 

Romingeria,  579;  cornuta,  584*, 
590 

Roofing-slate,  80§,  92, 112, 113*,  370, 
871 

Roots,  acidity  of,  and  the  corroding 
effects,  136  ;  destruction  by,  157* 

Rosa,  Monte,  glacier  region  of,  236, 
287,248 

Rosendale  cement,  555 

Rossberg  landslide,  in  1806,  208 

Rosso  antico,  86§ 

Rostellaria,  922  ;  nobilis,  854 

Rota  Island,  elevation  of,  350 

Rotalia  Boucana,  432*;  globulosa, 
432* 

Rothliegende,  697,  706 

Rotifers,  423,  455  720,  721 

Rotomahana  Lake,  305 

Rotten  limestone  group,  815,  823, 
824,  848,  854 

Rubidium,  335,  449 

Ruby,  64§ 

Rudistes,  840,  841*,  854,  861* 

Rupelian  beds,  926 

Rurutu  Islands,  37  ;  elevation  of, 
850 

Rusophycus  bilobatus,  545*,  546 


Russia,  34, 167  ;  upturnings  in,  630, 
734 

— ,  Cambrian  in,  482,  484,  518 ; 
Lower  Silurian,  518,  521,  588; 
Upper  Silurian,  533,  563,  566, 
567,  568,  569,  573;  Devonian, 
627;  Subcarboniferous,  693,  696, 
704 ;  Carboniferous,  690,  693,  697, 
710 ;  Permian,  686,  697,  707  ;  Tri- 
assic, 768;  Jurassic,  760,  775, 
776,  790,  794;  Cretaceous,  857; 
Tertiary,  923 

Rutoceras,  591,  602 

Ruwenzori,  Mt,  33,  296  (height) 

Sabal,  837,  921 ;  major,  933 
Sabine  River,  889,  890 
Sable  Island,  444,  944 
Saccammina  Carteri,  700 
Saccosoina  pectinata,  778*,  779 
Sacramento  River,  30,  809;  valley, 

749,  811,  818,  820,  830,  895 
Saganaga  Lake,  448 
Sageceras,  756 ;  Haidingeri,  757* 
Sagenaria  acuminata,  646 
Sagenopteris,  698,  704 
Saghalien,  40 
Saguenay  River,  948 
Sahara,  desert  of,  51 ;    plateau  of, 

26,34 

St.  Cassian  beds,  769,  774 
St.   Elias,   Mt.,   25,   238,   239*,  240 

(glaciers),  251,  390 
St.  George's  Shoal,  881,  889 
St.  Gothard  tunnel,  fossils,  310 
St.  Helena,  volcano  of,  290,  297 
St.  Helens  Island,  531,  558 
St.  Helens,  Mt.,  296,  945 
St.  John,  N.B.,  elevation,  350 
St.  Lawrence  Bay,  461,  541,  544 

—  channel,  536,  571 

—  Gulf,  444,  533,  537 ;  coal  making 
in,  708 

—  River,  40,   171,  536;    depth    of, 
948 

—  valley  in  the  Champlain  period, 
982 

St.  Louis  limestone,  634,  687,  688, 

646,  647 

St.  Mary  River  series,  880 
St.  Paul's  Island,  867 
St.  Peter,  Lake,  542 
St.  Peter's  Island,  867 

—  sandstone,  136,  491,  498,  494,  782 
St.  Vincent  Island,  168 
Salamander,  415,  920 

Salenia,  840,  860 

Salina  beds,  552 

Saline  deposits,  119 ;  efflorescences, 
138,  160 ;  springs,  200,  553 

Salinity  of  the  ocean,  121,  214 

Salisburia,  53,  435;  nana,  883; 
Sibirica,  833* 

Salix,  854,  922 ;  angusta,  839 ; 
Meekii,  837,  838* 

Salmon.  812,  879 ;  family,  862 

Salt,  63§  (see  also  Rock  salt)  ;  lakes, 
119,  881 ;  making,  120 ;  pans,  120, 
133,  134,  554,  791 ;  water,  subter- 
ranean, 320 

Salt  Lake  City,  360*,  361 

Salt  Range,  India,  483,  698,  770,  776 


1078 


INDEX. 


Salt-works  of  Salina,  553,  554 
Salterella,  471 ;  Billingsi,  515 ;  Mac- 

cullochi,  573 ;  pulchella,  471, 472* ; 

rugosa,  578 
Salton  Lake,  200 
Saltonstall  Ridge,  801* 
Saltpeter,  63§,  137 
Salvinia,  584,  718 ;  natans,  435, 436* 
Samoan  Islands,  36,  88,  145,  283, 

297 

San  Bernardino,  Pass  of,  160 
San    Francisco     Mountains,    660; 

peninsula,  884,  892 ;  Eiver,  885 
San  Gabriel  Range,  892 
San  Juan  Mts.,  363 
Sand,  75§,  76§  ;  barriers,  223,  224*  ; 

bars,  192,  193,  202,  212,  216,  225, 

226*,  227*;  hills  on  sea  shores, 

94,    155,    161,    162;    rock,    80§; 

scratches,  160 ;  spits,  increase  of, 

223,  224 

Sand-blast,  carving  by,  161 
Sand-flea,  420*,  421§ 
Sand-worm,  423 
Sandstone,    80§;    dikes    or   veins, 

344*,  811,  876 

Sandstones  of  Condros,  625 
Sandusky  limestone,  581 
Sandy  Hook,  formation  of,  224,  225 
Sangay,  26 

Sangre  de  Cristo  Range,  266 
Sanidin,  84§,  88 ;  trachyte,  84§ 
Sannionites,  501 
Sannoisian  stage,  926 
Santa  Cruz  beds,  927 ;  Islands,  vol- 
canoes of,  296  ;  Mts.,  892 
Santa  Inez  Range,  892 
Santa  Lucia  Mts.,  892 
Santa    Maria   Island,  elevation   of, 

849 

Santa  Monica  Range,  892 
Santa  Suzanna  Range,  892 
Santee  beds,  888 
Santo  Domingo,  19,  935 
Santonian,  859,  866 
Santorin  Island,  296  (volcanoes) 
Sao  hirsuta,  481*,  482 
Sao  Miguel,  geysers  of,  308 
Sapindus,  838,  896 ;  Morrisoni,  838 
Saportsea,  685 
Sapphire,  64§ 
Sapphirina  Iris,  420*,  421 
Sarcinula,  640 ;  obsoleta,  511*,  515 
Sardinia,  Cambrian  in,  482 ;  Upper 

Silurian,  563,  564 
Sargasso  Sea,  45,  121,  148,  156 
Sargassum,  437 
Sarmatian  stage,  927 
Sarotes  venatorius,  168 
Saskatchewan  River,  29,  203,  947 
Sassafras,   812,   831,  837,  879,  921 ; 

Cretaceum,  837,  838* 
Sat  valley,  240 

Saurichthys,  772  ;  apicalis,  774 
Saurocephalus,  862 ;  lanciformis,  844 
Saurodon  lanciformis,  844 
Saurodonts,  826,  843,  862 
Sauropods,  761,  762-764,  786,  867 
Sauropus  primaevus,  645* 
Saussurite,  65§,  88,  318, 319 ;  rocks, 

82,88 
Sarage  Island,  elevation,  350 


Savaii,  283 

Saxicava,  157;  arctica,  983,  984; 
rugosa,  984,  995 

Saxifraga,  240 ;  oppositifolia,  945 

Saxony,  Archaean  in,  455,  456 ;  Per- 
mian, 706,  707 ;  Triassic,  768 

Scalaria,  916,  922;  Bowerbankii, 
925 ;  Groenlandica,  984 ;  Hercules, 
854 ;  Sillimani,  854 

Scalent  series,  728 

Scales,  Fish,  analysis  of,  73 

Scalites  angulatus,  502* 

Scandinavia,  32,  43,  256;  fiords 
of,  948;  Archaean  in,  456;  Cam- 
brian, 482 ;  Lower  Silurian,  521 ; 
Upper  Silurian,  563,  568,  569, 
573;  Cretaceous,  857;  Glacial, 
948.  See  also  Norway ;  Sweden  ; 
etc. 

Scandinavian  plateau,  19 

Scaphaspis  Ludensis,  567 

Scaphiocrinus,  646,  690 ;  Missouri- 
ensis,  640*,  646 

Scaphites,  854;  aequalis,  866;  Con- 
radi,  842*,  854, 855 ;  Geinitzi,  866 ; 
hippocrepis,  854 ;  larvaeformis, 
842*,  843,  855 ;  nodosus,  855 ;  pul- 
cherrimus,  866 ;  Texanus,  855 ; 
ventricosus,  855 ;  vermiformis, 
855 

Scaphodus  Ludensis,  567 

Scaphopods,  424§ 

Scapolite,  65§,  79,  310,  818,  820 

Scar  limestone,  695 

Scaumenacia,  621 

Scelidosaurus,  787 

Scelidotherium,  1003 

Scenella,  482 ;  reticulata,  472*  ;  re- 
tusa,  472* 

Schillerization,  321 

Schist,  83§,  84§ 

Schistose  rocks,  82,  83 

Schistosity,  113§,  371 

Schizaster  atavus,  866 

Schizobolus  truncatus,  612 

Schizocrania  filosa,  507*,  514 

Schizocrinus,  532 ;  nodosus,  514 

Schizodus,  602,  621,  687,  W  ;  am- 
plus,  690;  Chesterensis,  647; 
dubius,  707 ;  obscurus,  707 ; 
quadrangularis,  620 ;  Rossicus, 
685 ;  Schlotheimi,  707 ;  truncatus, 
707 

Schizopods,  439§,  703 

Schizotherium,  918 

Schlern  dolomyte,  774 

Schkenbachia  Belknapi,  836;  cris- 
tata,  865 ;  dentato-carinata,  855 ; 
inflata,  865;  Peruviana,  886; 
varians,  866 ;  varicosa,  865 

Schlrenbachia  clays,  836 

Schoharie  epoch,  410,  576,  579  ;  grit, 
576,  579,  587,  590,  591,  601,  628 

Schorl  rock,  88§ 

Schuylkill  River,  816 

Scirpus,  75 ;  caespitosus,  946 

Sciurus,  910,  918 

Scolithus,  428,  470 ;  linearis,  477* 

Scolopendra,  419,  724 

Scoria,  266,  267§,  281*,  282 

Scoriaceous  lavas,  280§,  281*,  298 ; 
rocks,  78§ 


Scorpions,  420,  564,  722§,  724; 
Upper  Silurian,  556,  565,  574, 
722;  Devonian,  575;  Carbon- 
iferous, 677,  691,  701* 

Scotland,  155,  218,  229,  258,  288,  453, 
534;  Archaean  in,  453,  456,  457; 
Cambrian,  457,  481  ;  Lower 
Silurian,  518,  520,  524;  Upper 
Silurian,  563,  565,  573;  Devo- 
nian, 622,  623,  625  ;  Subcar- 
boniferous,  695 ;  Carboniferous, 
702,  703  ;  Permian,  697  ;  Triassic, 
768,  773;  Jurassic,  775;  great 
thrust  movement  in  Highlands 
of,  534 

Scratches,  95,  96§ 

Scratching  by  drifting  sand,  160; 
by  icebergs,  252;  by  slides  of 
rock,  249* 

Scutella,559    > 

Scutella  limestone,  559 

Scyphia  digitata,  513 

Scyphian-Kalk,  790 

Sea-anemone,  431§ 

Sea  bottom,  changes  in  level  of, 
345,  348,  949 

Sea  water,  salts  of,  composition  of, 
120 ;  dolomization  by  means  of, 
134 

Seals,  415 

Seam,  92§ 

Seaweeds,  56,  75,  143,  155,  436§ 

Secondary  formations,738;  minerals, 
*320§,  323,  332,  340,  341;  rocks, 
408§,  880 

Secretary  Bird,  923 

Section,  general,  of  geological  series, 
410*,  411* 

—  of    Adirondacks,     Can.,     452* ; 
Appalachians,   102*,    109*,    355*, 
356*;  Arch;ean,  451*;  Bald  Mt., 
N.  Y.,  528* 

—  of  Coal-measures  at  Trevorton 
Gap,   650*  ;    Coal-measures  near 
Nesquehoning,  649* 

—  of  Colorado  Plateau,  110*,  363*  ; 
Cumberland    Table-land,    Tenn., 
356* 

—  of  Dent  de  Morcles,  367* ;  Mt. 
Eolus,    Vt.,    530*  ;    at    Genesee 
Falls,  91*,  542;  of  Greylock  Mt., 
Mass.,  530* 

—  of  Hamilton    beds,   Lake  Erie, 
594*;  Hawaii,  269*;   Himalayas, 
82*,  368*  ;  Jura  Mts.,  368* 

—  of  Mt.  Loa,   286* ;  of  Portland 
dirt-bed,  776*  ;   at  Niagara  River, 
540*  ;  of  Paleozoic  at  Pottsville, 
650* 

—  (Prosser's)  of  New  York  rocks 
near  Rochester,  605;  (Prosser's) 
of   Pennsylvania  rocks,   Munroe 
Co.,  594,  606 

-  on  the  Schuylkill,  Pa.,  650*; 
of  Snake  Mt.,  Vt.,  528*;  Taconic 
Range,  near  Montmorenci  Falls, 
527* ;  Tennessee  Rocks,  856* ; 
Timpahute  Range,  366*;  Utah 
ore-beds,  339* 

—  showing  cavern-making  in  lime- 
stone,   130*;    of  decaying   lime- 
stone, Amenia,  N.Y.,  126 


INDEX. 


1079 


Section  of  Alps,  102*,  110* ;  Car- 
bonate Hill,  Leadville,  341*; 
Coal-measures,  651-662,  656,  657 ; 
Kilauea,  284*,  285* 

—  of  Laramide  Mountain  range, 
Brit.  A.,  359* 

Sediment,  76§,  167§ ;  ratio  of,  to 
water,  190 

Sedimentary  rocks,  167§  ;  sedimen- 
tation more  rapid  in  salt  water 
than  in  fresh,  209,  210,  217 

Sedum  rhodiola,  945 

Seeds,  transportation  of,  156,  168 

Seiches,  202§ 

Seine,  191 

Seismograph,  seismometer,  seismo- 
scope,  375§ 

Selachians,  415§,  416* 

Selaginella,  718 

Selenium,  331 

Selkirk  Mts.,  240 

Selvage,  332§ 

Semele  Stimpsoni,  927 

Seminula  subtilita,  675*,  685,  690 

Semi-oviparous  Mammals,  415 


Senonian  group,  815,  858,  859,  860, 


Sepia,  424 

Septaria,  97*,  188*  (quartzyte) 

Sepulchre  Mt.,  937 

Sequanian  group,  790 

Sequoia,  816,  831,  837,  840,  859,  921, 

939 ;  ambigua,  838 ;  gigantea,  939  ; 

gracilis,    834 ;    Langsdorffi,   921 ; 

Reichenbachi,  834, 839 ;  Smittiana, 

833*,  834 
Serai  series,  728 
Sergestes  mollis,  52 
Sergipian  group,  867 
Sericite,  65§ ;  schist,  84,  88,  89 
Sericitschiefer,  84 
Series,  406§ 
Serolis,  420* 
Serpentine,  68§,  319§ 
Serpula,  423 
Serpulidae,  59 
Serpulites  dissolutus,  515 
Serripes  Groenlandicus,  983,  984 
Sertularia,    430*§ ;    abietina,  430*; 

rosacea,  430* 
Sevier  Lake,  119 
Sewickley  coal-bed,  651 
Seychelles  Islands,  737 
Shakopee  limestone,  498 
Shale,  shaly  structure,  80§,  92§ 
Shan-a-lin  Mts.,  32 
Shan  si,  696 
Shan-Tung,  198 
Sharks,  56,  60, 73  (analysis  of  bones), 

415,  416*  ;  teeth  of,  dredged,  144. 

See  Selachians 

Sharon  coal-beds,  656;  conglomer- 
ate, 648,  656 
Shasta,  Mt.,  87,  267*;  glaciers  of, 

240,  945  ;  height  of,  296 

—  group,  818 ;  Aucellae  of,  834 
Shasta-Chico  series,  809,  815,  820, 

830,  868 
Shawangunk  grit,  538,  539,  541 

—  Mts.,  538,  946 
Shawnee  coal-bed,  828 


Shear-zones,  111§,  322§ 
Shearing,  168§,  216,  322 
Sheep-backs,  250*§ 
Shell-beds   or  heaps,  98,    158;    of 

Maine,  983,  994 
Shell  Bluff,  Ga.,  916 
Shell-limestone,  79§,  151 ;  marl,  79§ 
Shenandoah  valley,  357 
Shenango  group,  638 
Sheppey,  Isle  of,  921,  923,  925 
Sheridan,  Mt.,  height  of,  296 
Shetlands,  87,  218 
Shinarump  Cliffs,  747 
Ship  worm,  158 
Shoal  Creek  limestone,  817 
Shore-lines,  elevated,  in  region  of 

Great  Lakes,  906;    about  Lake 

Winnipeg,  985 

Shore-platforms,  220,  221*,  222* 
Shoshone  Lake,  200,-  305 

—  Range,  366,  945 
Shot,  angle  of  rest  of,  165 
Shrimps,  420,  438,  615* 
Shrinkage  cracks,  94*§,  464 
Siam,  22 

Siberia,  32,  166,  195,  776,  794,  833, 
927 

Sicily,  296,  431,  921 

Siderite,  69§,  126,  344,  449,  664, 
665 

Sierra  Blanca,  874 

Sierra  Chain  and  System,  365,  389, 
811 

Sierra  de  Salina,  892 

Sierra  Madre,  444,  758 

Sierra  Nevada,  25,  27 ;  buried  river 
valleys,  204;  volcanoes  of,  296; 
river  systems  of,  934;  glaciers 
of,  240 ;  upturnings  at  close  of 
Jurassic,  809,  814;  elevation  in 
the  Tertiary,  366,  932 

— ,  Archaean  in,  444;  Upper  Silu- 
rian, 810 ;  Carboniferous,  635, 
659;  Triassic,  746,  747,  758, 
809;  Triassic  and  Jurassic,  739, 
809;  Jurassic,  358,  748,  760,  809 
(close  of),  810,  932  ;  Tertiary,  366, 
883,  887,  892,  895,  934  (elevation), 
935,  937  (eruptions) ;  Glacial,  945 

Sierra  San  Carlos,  820 

Sigillaria,  611,  639,  654,  667,  668, 
682,  689,  698,  699;  Brardii,  689, 
693,  705;  Halli,  595*;  Lescurii, 
689  ;  mammillaris,  689  ;  Menardi, 
689  ;  monostigma,  689  ;  palpebra, 
622  ;  Pittstonana,  668*,  688 ;  Silli- 
mani,  668*,  688;  tesselata,  689; 
Vanuxemi,  609* 

Sigillarids,  698,  712,  718,  750 ;  Car- 
boniferous, 669,  670,  672,  688; 
Coal-measure,  653  ;  Permian,  684, 
704,  718  (last) 

Silene,  240 ;  acaulis,  945 

Silesia,  88;  Coal-measures  in,  696, 
702,  708 

Silica,  62§,  63,  135-136 ;  as  a  solidi- 
fier,  323 

Silicates,  62§,  63,  64-68 

Siliceous  deposits,  82,  152,  305,  306, 
808,  309,  335,  441 

—  Claiborne,  885,  888" 

—  group,  Tenn.,  638 


Siliceous  organic  rock-material,  72§r 
140, 141 

—  rocks,  80,  81,  82 ;  slate,  82§ 

—  solutions,  82,  94,  97 

—  sponges,  431§ 
Silicified  wood,  125,  185 
Silicon,  62§,  63 ;  fluoride,  66 
Sillery  sandstone,  467,  496 
Sillimanite,  319 

Silt,  81  §,  150,  167§,  177,  190,  198, 

628;  of  rivers,  amount  of,  190 
Silurian,  535 

—  and    Cambrian,   history    of   the 
terms,  463,  464§,  489 

— ,  Lower,  489 ;  European,  517  ; 
economical  products,  522;  gen- 
eral observations,  524;  the  Cin- 
cinnati uplift  at  close  of,  387,  532, 
537 

— ,  Upper,  535 ;  foreign,  563 ;  gen- 
eral observations,  570 

Siluric  era.    See  Silurian 

Siluroids,  843 

Silver  Canon,  366* 

Silver  Cliff,  340 

Silver-moth,  702 

Silver  Peak,  469 

Silverado,  733 

Simeto,  erosion  of  the,  184 

Simoceras,  793 

Simosaurus,  773 

Sind,  299,  770,  925 

Sindree,  changes  of  level  at,  849 

Sineraurian  group,  775;  (Lower), 
790 

Singala  Mt.,  368* 

Sinopa,  918 

Sinter,  82§ 

Sinupallial,  425§ 

Sioux  quartzyte,  468 

Siphocypraea  problematica,  917 

Siphonaria  Penjinae,  927 

Siphonema,  503 

Siphonia  lobata,  860* 

Siphonotreta,  521 ;  unguiculata. 
427* 

Sitomys,  918,  919 

Sivatherium,  927 

Siwalik  Hills,  923,  927,  988  (Tertiary 
beds),  936 

Skiddaw  slates,  517,  519,  520 

Skye,  938 

Slate,  83§,  92§  ;  siliceous,  82§ 

Slates,  auriferous,  748,  759,  809 

Slaty  cleavage  or  structure,  77,  92§, 
112§,  113*,  370,  371 

Slaty  Peak,  Col.,  height  of  Creta- 
ceous rocks,  935 

Slaty  rocks,  66 

Slickensides,  96§,  108,  111 

Slimonia,  567 

Slope  of  loose  materials,  165 

—  of  mountains,  26,  27*§ ;  of  Eocky 
Mts.,  26* 

Sloth,  54 

Smaragdite,  88 

Smilax,  435 

Smilodon,  1000 

Smithsonite,  342 

Snails,  424,  425* 

Snake  Mt.,  fault  at,  527,  528* 

Snake  River,  300,  805 ;  plains,  988 


1080 


LNDEX. 


dnakes,  415,  848;  Carboniferous, 
726;  Cretaceous,  848,  870;  Ter- 
tiary, 202,  901,  923 

Snow-drifts,  162 

Snow-line  on  heights,  233,  284 

Soapstone,  67§,  68,  89§ 

Society  Islands.    See  Tahitian 

Soda,  61  §  ;  in  plants,  74,  75 

Soda-granite,  86§ 

Soda  Springs,  Idaho,  746 

Sodalite,  81,  85,  449,  876 

Sodium,  61,  63, 120 

Soil,  81§  ;  moved  by  frost,  281 

Solarium  ornatum,  866;  planorbis, 
836 ;  triliratum,  916 

Solemya,  602 

Solen,  425§,  916,  917 

Solen  beds,  892 

Solenhofen,  776,  783,  784,  786,  788, 
796,  852 

Solenoceras  annulifer,  854 

Solenomya  radiata,  690;  vetusta, 
590  (first  known) 

Solenopora  compacta,  514 

Solfataras,  128,  265,  278,  283,  293§, 
295,  334 

Solidification,  258,  264,  326 ;  of  the 
earth,  376 

Solids,  flow  of,  351-852 

Solitaire,  1014 

Soloman  Islands,  86,  38,  156 

Solution,  118-122 

Solva  group,  481 

Somma,  Mt.,  276,  291 

Sonora,  747,  748  (gold  placers),  749, 
755,  756 

Sorata,  Mt.,  27 

Sorrel,  945 

Souris  Eiver  beds,  880 

South  Africa,  406  ;  united  with  In- 
dia, 873,  937  ;  and  Australia,  874, 
937;  no  fiords,  948;  Paleozoic 
in,  699  ;  Carboniferous,  699  ;  Per- 
mian, 698,  699,  707,  737  ;  Triassic, 
707,  737,  770,  773,  791 ;  Jurassic, 
791 ;  Quaternary,  1019 

South  America,  16, 18 ;  mean  height 
of,  23 ;  surface  features  of,  30 ; 
volcanic  cones  of,  274  ;  elevations 
of,  347,  874,  877  :  Cordilleras,  390 ; 
fiords  of,  948 ;  Archaean  in,  442, 
450;  Cambrian,  483;  Devonian, 
627;  Carboniferous,  682,  659, 
693,  711;  Cretaceous,  857,  867; 
Tertiary,  865,  456;  elevation 
during,  927,  985;  post-Mesozoic 
mountain-making,  874 ;  Glacial, 
948 

South  Carolina,  mean  height  of, 
23  ;  phosphatic  deposits  of,  153 ; 
earthquakes  of,  373 

South  Dakota,  mean  height  of,  28 ; 
Cambrian  in,  464,  468,  476 ;  Nia- 
gara, 541;  Cretaceous,  828,  838, 
856 ;  Tertiary,  909 

South  Mtn.,  Pa.,  465,  532 

South  Park,  495,  886,  898 

South  Shetlands,  296  (volcanoes) 

Spjtin,  plateau  of,  26 ;  volcanoes  of, 
296;  Cambrian  in,  484;  Lower 
Silurian,  518 ;  Upper  Silurian,  568, 
573  ;  Subcarboniferous,  693 ;  Car- 


boniferous, 693;  Jurassic,  775, 
793 ;  Cretaceous,  857  ;  Tertiary, 
920,  982 

Spalacodon,  926 

Spalacotherium,  789* 

Spanish  Peaks,  296,  318,  876 

Sparnacian  group,  925 

Spathiocaris  Emersoni,  620,  621 

Species,  difference  in,  attending  dif- 
ference in  environment,  402 

Specific  gravity  in  relation  to  fusi- 
bility, 304 

Specular  iron,  70,  88,  578;  rocks, 
83 

Speeton  Cliffs,  865 

Sperm  Whale,  912 

Spermatophilus  Eversmani,  156 

Sphserexochus,  521 ;  mirus,  520, 
565* ;  parvus,  503 

Sphseriurn,  152,  856 

Sphaeroceras,  760 

Sphaerocystites,  562 

Sphaerophthalmus,  481 

Sphaerospongia,  596 ;  tesselata,  597*, 
601 

Sphaerozoum  orientale,  433* 

Sphaerulites,  861 ;  Hceninghausi, 
861* ;  Texanus,  836 

Sphagnum,  73  (ash),  153;  com- 
mune, 74 

Sphalerite,  70§,  125,  333,  340,  542, 
687 

Sphenacodon,  688 

Sphene,  67 

Sphenella  glacialis,  699 

Sphenodiscus  lenticularis,  854 ; 
pleurasepta,  855 

Sphenodon,  687  ;  punctatum,  54 

Sphenolepidium,  831 ;  Virginicum, 
834 

Sphenophyllum,  639,  671,  685,  698, 
699,  704 ;  antiquum,  622 ;  emargi- 
natum,  689;  filiculme,  692,  693; 
longifolium,  689,  704;  Schlot- 
heimi,  671*,  689  ;  vetustum,  583* 

Sphenopteris,  639,  671,  685,  689, 
693,  698,  699,  704 ;  arguta,  791 ; 
cristata,  645;  flaccida,  626;  fur- 
cata,  689;  Gravenhorstii,  670*, 
689;  Grevillioides,  888;  Hartti, 
622 ;  Hildrethi,  670*,  689 ;  Hitch- 
cockiana,  622 ;  Hoeninghausi,  622 ; 
Hookeri,  626 ;  Humphriesiana, 
626;  Mantelli,  831,  882*;  Schim- 
peri,  704  ;  spinosa,  689  ;  tridactyl- 
ites,  689  ;  Valdensis,  834 

Sphenopterium  obtusum,  646 

Sphenotus,  621 ;  contractus,  621 

Spherophyric,  77§  ;  rocks,  83§,  84 

Spherulites,  84,  96,  97,  289,  388 

Sphyradoceras,  591 

Sphyrenids,  843 

Spicules  of  sponges.  See  Sponge- 
spicules 

Spiders,  141,  163,  420,  525,  722,  723, 
724 ;  Upper  Silurian,  574 ;  Devo- 
nian, 575;  Carboniferous,  657, 
674,  677,  701,  722  (first) ;  Paleo- 
zoic, 722,  723,  727 ;  Tertiary,  893, 
901 

Spinax  Blainvillii,  416* 

Spinel,  313,  449,  453 


Spirifer,  810,  401,  425§,  426*§,  550, 

561,  562,  568,  579,  592,  606,  642, 
705,  719;  acuminatus,  585*,  590, 
591 ;  alatus,  707 ;  altus,  612 ;  are- 
nosus,  578*,  579;  arrectus,  579; 
asper,   602 ;    bimesialis,  602 ;    bi- 
plicatus,  642*,  646 ;  borealis,  758 ; 
canaliferus,  625 ;  cameratus,  675*, 
685,  690 ;  Clannyanus,  707 ;  Con- 
radanus,  591 ;  Cooperensis,  646 ; 
crispus,  563,  567,  568 ;  cultrijuga- 
tus,  626,  627  ;  curvatus,  625 ;  cus- 
pidatus,    703;    cyclopterus,    562, 
563 ;  decussatus,  626 ;  disjunctus, 
370*,  592,  612,  613*,  621,  622,  625, 

626,  628,    703;    Dumonti,    626; 
duodenarius,  591 ;  elevatus,  567, 
568;    exporrectus,  520;   fimbria- 
tus,  591,  601,  602;  fragilis,  773, 
774 ;  giganteus,  370* ;  glaber,  627 ; 
700*;    glaber    (var.    contractus), 
647  ;  granuliferus,  601 ;  gregarius, 
585*,  590,  591 ;  Hungerfordi,  602 ; 
hystericus,  625 ;  incrassatus,  704 ; 
increbescens,  642*,  646 ;  Keokuk, 
646;    laevicostatus,    625;     laevis, 
612* ;  lineatus,  690,  704 ;  Logani, 
646;     macropleurus,    560*,    561, 

562,  563;   Marionensis,  602,  646; 
Meeki,   646;    mesacostalis,   620; 
mesastrialis,    620 ;    mucronatus, 
601;  Munsteri,  774;  Niagarensis, 
548*,  551,  563 ;  Parryanus,  602 ; 
pennatus,    598*,    602;    perlamel- 
losus,  562,  563;  plicatellus,  520; 
pyxidatus,  579 ;  radiatus,  522, 550, 
551 ;    raricosta,    592 ;    speciosus, 
703;     striatus,    426*;     sulcatus, 
548*,  551,  562,  563,  567 ;  Urii,  626, 

627,  707 ;  Vanuxemi,  558 ;    vari- 
cosus,  592;    Verneuili,  626,  627, 
628 ;  Whitneyi,  602 

Spiriferids,  574   . 

Spiriferina,  756,  790 ;  cristata,  707 ; 
Kentuckensis,  690;  octoplicata, 
707 ;  spinosa,  642*,  646,  647 ;  Wal- 
cotti,  779*,  790 

Spirifersandstein,  570 

Spirocyathus  Atlanticus,  470* 

Spirophyton,  601,  688;  caudagalli, 
582*,  667,  688 

Spirorbis,  675 ;  arietinus,  691 ;  car- 
bonarius,  676*,  691 ;  laxus,  558 

Spitzbergen,  48,  395,  758;  Subcar- 
boniferous in,  696,  704;  Carbon- 
iferous, 635,  696,  704,  711 ;  Per- 
mian. 704;  Triassic,  768,  774, 
792 ;  Jurassic,  776  ;  Cretaceous, 
868,  872  (climate)  ;  Tertiary,  922, 
939  (Sequoia) 

Spodumene,  321,  332,  449 

Spondylus,  130 ;  gregalis,  854 ;  spi- 


Sponge-beds,  777,  790 

Sponges,  Sponge-spicules,  57,  64, 
72,  140,  141,  419,  431§,  432*,  474*, 
513,  515,  588*,  590,  596,  601,  611, 
777,  860* 

Spougillae,  432 

Spongiolithis  appendiculata,  894* 

Sporangi  in  coal,  655* 

Sporangites,  601 ;  Corniferous,  584 ; 


INDEX. 


1081 


Hamilton,   596;   Chemung,   610, 

611,  612 ;  Coal-measure,  655 
Sporangites  Huronensis,  610,  612 
Spores,  582*,  584,  611,  718 ;  in  coal, 

654,  655*,  712 
Spring  Hill,  783 
Springs,  205.  See  also  Hot  springs ; 

Mineral ;      Sulphur ;       Thermal 

waters 

Spruce,  435,  436,  667,  668,  770,  859 
Spyroceras,  602 
Squalodon,  912,  927 
Squalodonts,  843*§,  863,  869 
Squalus  cornubicus,  78 
Square  Lake,  Me.,  552,  558 
Squash-bug,  419 
Squid,  424*§,  525,  758,  776 
Squirrels,  910 
Stages,  407§ 
Stagodon  tumidus,  853*;  validus, 

853* 

Stagonolepis,  778 
Stags,  907,  927,  930,  1002,  1013 
Staked  Plains,  885,  895.     See  also 

Llano  Estacado 
Stalactites,  79§,  131,  294*,  695 
,-  and  stalagmites  at  Kilauea,  294*, 

295,  324 

Stalagmites,  79§,  92,  131,  294* 
Stampian  stage,  926 
Stangeria,  718 
Star  Peak  groups,  747 
Starfishes,  158,  428§,  429* 
Starucca  sandstone,  606 
Staten  Island  clay -beds,  821,  823 
Statuary  marble,  79§ 
Staurolite,  65*,  66§,  319,  449 
Staurolitic  rocks,  83,  310 
Steam,  300, 338  ;  in  metamorphism, 

312,  323,  354 
3teamboat  Springs,  323  ;  superficial 

vein-making  at,  334,  335 ;  depos- 
iting gold,  335 
Steatite,  67§ 
Steatyte,  89§,  450 
Steel  ore,  69§ 
Stegocephs,  681§,  687 
Stegosaurids,  863 
Stegosaurs,  Stegosaurians,  761,  764, 

787,  796 
Stegosaurus,  765*,  787;  ungulatus, 

764* 

f^elletta,  432* 
Stemmatopteris,     699  ;     punctata, 

669*,  689 

Stenaster  Huxleyi,  499*,  500 
Steneofiber,  918,  919 
Steneosaurus,  790 
Stenocrinus,  516 
Stenogale,  919 
Stenopora,  524 ;    fibrosa,  508,  517, 

567 ;  Petropolitana,  517 
Stenotheca,  481  ;     Acadica,    475*  ; 

rugosa,  472* 

Btenotrema  hirsutum,  967 ;  mono- 
don,  966 
Stephanoceras      Humphriesianum, 

781*,  790  ;  macrocephalum,  791 
Stephanocrinus,    547*  ;    angulatus, 

547*,  550 

Sterculia  modesta,  839 
Stereocaulon  Vesuvianum,  186 


Stereognathus,  789* 
Stereosternum,  706 ;  tumidum,  687 
Sternbergia,  673 
Sthenopterygians,  417 
Stibarus,  918 
Stictopora,  514,  550 
Stictoporella,  505  ;  cribrosa,  506* 
Stigmaria,  627,  645,  653,  658,  669*, 

670,    699,    704;    anabathra,  645; 

ficoides,    646,    699;   minor,    645; 

minuta,  645 ;  perlata,  622 ;  pusilla, 

622 ;  umbonata,  645 
Stikine  Eiver,  glaciers  of,  240 
Stilbite,  68 
Stinkstein,  697 
Stiper  stones,  517 
Stissing  Mtn.,  467 
Stockbridge  limestone,  467, 491,  528, 

530 

Stomapod,  783 

Stomatopora  arachnoidea,  514 
Stone  age,  1008 
Stone  coal,  661 ;  rivers,  209§ ;  state, 

264 

Stones  on  sea  bottom,  144 
Stonesfield  slate,  411,  775,  777,  787, 

788,  789,  790 
Stony  Creek,  Conn.,  949 
Stormberg  beds,  699,  770 
Strain,  level  of  no.    See  Zero-strain 
Strangeria,  596 
Straparollus,    495,  515,  707;  Clay- 

tonensis,  501 ;  lens,   647 ;  perno- 

dosus,   690 ;    pristiniformis,  501 ; 

similis,    647  ;    Spergensis,    647  ; 

subrugosus,  690 
Strata,  stratification,  91*§ 
Straticulate,  92§ 

Stratified  formations,  90-116  (struc- 
ture and  characteristics,  90 ;  cal- 
culating thickness  of,  113,  114* ; 

conformability,  unqonformability, 

114),  398,  441,  450 
Stratigraphical,  91§ 
Stratum,  91§ 
Strephochetus,  502 
Stpepsidura  ficus,  916 
Streptaxis  Whitfieldi,  690 
Streptelasma,    550,  562;    apertum, 

513  ;  calyculus,  550 ;  corniculum, 

504,  505*,  513;  expansum,  503; 

profundum,  513 
Streptorhyncus      crassum,       690 ; 

crenistria,  625,   626,  700*  ;    um- 

braculum,  625,  704 
Striae.    See  Scratches 
Striarca  centenaria,  899*,  917 
Stricklandia  lens,  520,  567 ;    lyrata, 

567 

Strike,  99*,  100§,  101,  105* 
Stringocephalus  Burtini,  595,   601, 

625,  626 
Stringocephalus    beds,     626,    627  ; 

zone,  595,  601 
Strobilospongia,  513 
Stromatocerium  pustulosum,  514 
Stromatopora,   455,  499,   547,    551, 

562,  584,  625;  concentrica,  547*, 

550,  569 ;  ponderosa,  590 
Stromatoporids7447,  504 
Strombodes  gracilis,  550 
Stromboli,  276,  280 


Strombus  Aldrichi,  899*,  917 ;  Lei- 
dyi,  917  ;  Sautieri,  865 

Strontium,  335 

Strophalosia,  707  (ends  with  Per- 
mian) ;  excavata,  707  ;  Goldfussi, 
707 ;  lamellosa,  704 ;  productoides, 
628 ;  truncata,  620 

Stropheodonta,  551,  562,  579,  642; 
arcuata,  602 ;  Cayuta,  621 ;  de- 
missa,  591,  602  ;  filosa,  567 ;  mag- 
nifica,  579;  mucronata,  620;  na- 
crea,  602  ;  perplana,  591, 592,  602 ; 
punctulifera,  592  ;  reversa,  602 ; 
varistriata,  558 

Strophodus,  772  (first),  783 

Strophomena,  425§,  426§,  503,  516, 
517,  520,  521,  552,  562  ;  alternata, 
503,  507*,  514,  524 ;  arenacea,  520, 
567;  compressa,  567;  deltoidea, 
521 ;  depressa,  551,  626 ;  expan- 
sa,  521 ;  incrassata,  514 ;  pecten, 
568 ;  planumbona,  426*,  503 ;  pli- 
cifera,  502*,  503;  rhomboidalis, 
503,  625;  rugosa,  568;  subplana, 
563 ;  Woolworthana,  563 

Strophomenids,  568 

Strophonella  euglypha,  567 ;  radi- 
ata,  560* 

Strophostylus,  562 ;  cancellatus,  579 

Structural  geology,  14§,  61-116 
(rocks,  61 ;  terranes,  89) 

Struthio,  54 

Struthiosaurus,  864 

Sturgeon  Kiver,  445 

Sturgeons,  59,  923 

Stylacodon,  768 ;  gracilis,  767* 

Stylina,  760 ;  tubulifera,  759* 

Stylinodon,  905 

Styliola,  59* 

Styliolina,  586,  599  ;  fissurella,  592, 
598*,  602,  603,  612,  620,  621 

Styliolina  limestone,  603,  613,  621 

Stylodon,  789* 

Stylolites,  543,  555 

Stylonurus,  567,  623  ;  excelsior,  615 ; 
Wrightianus,  615 

Sub-,  as  a  prefix,  407§,  634§ 

Subapennine  marls  and  sands,  927 

Subcarbon  period,  632 

Subcarboniferous  period,  636 

Sub-Himalayas,  933,  936 

Sub-Oleon  conglomerate,  638 

Subretopora  incepta,  502* 

Subsidence,  151,  345,  846,  347; 
Champlain,  981 ;  modern,  348, 
849,  350,  378,  392;  through  the 
Paleozoic,  380,  385 

— ,  coral  island,  the  counterpart  of 
continental  elevation,  937 ;  of  the 
Pacific  indicated  by  coral  islands, 
149,  350,  392;  rate  of,  in  coral 
islands  and  in  the  history  of  coral 
reefs,  149*,  150,  151,  202 

Subterranean  waters,  204-209 

Subulites,  514  ;  ventricosus,  551 

Succinea  avara,  966  ;  obliqua,  966 

Suchoprion  aulacodus,  754 

Suessonian  group,  884,  925 

Suillines,  930 

Sulcopora  fenestrata,  502*,  508 

Sulphates,  63§,  69 

Sulphides,  70 


1082 


INDEX. 


Sulphur,  63§,  70;  in  coals,  661,  663, 
664 

—  springs,  125 ;  in  California,  335 ; 
in  New  York,  554,  555 

Sulphuric  acid,  63§ ;  springs,  125, 
555 

Sulphurous  acid,  63§,  124,  125,  324  ; 
from  volcanoes,  278§,  293,  294 

Sumatra,  22,  88,  40;  volcanoes  of, 
297 

Sun,  a  chief  source  of  geological 
energy,  117 ;  causes  of  the  vary- 
ing degree  and  effects  of  its  heat, 
253-257 ;  its  heat  as  related  to  the 
ocean's  work,  166,  209,  214;  as 
affecting  the  temperature  and 
density  of  water,  214 

—  spots,  11-year  cycle  of,  177,  255 
Sunderland  Lake,  533 
Superga,  molasse  of,  926 
Superior,  Lake,  29,  40,  85,  166,  200, 

201*,  206,  483 ;  basin,  106,  199  ; 
copper  veins,  272,  823,  338,  339, 
465,  466 

Superposition,  order  of,  899, 400 

Surcula,  916 

Surficial,  1988,  272§ 

Surgent  series,  728 

Surirella  craticula,  164*,  165 

Sus,  54,  927 

Susquehanna  River,  888,  465,  780*, 
781,  816 

Sussex  marble,  864 

Swabia,  788 

Swallows,  923 

Sweden,  Archaean  in,  456;  Cam- 
brian, 482,  484,  518 ;  Lower  Silu- 
rian, 518,  519,  520,  521;  Upper 
Silurian,  563,  564,  565,  568,  569, 
573;  Triassic,  769;  Cretaceous, 
888 

Switzerland,  Cretaceous  in,  857, 859 ; 
Jurassic,  783  ;  Tertiary,  920,  925, 
926 

Sydney  sandstone,  Australia,  221 

Syenite,  85§  ;  granite,  85§ 

Syenyte,  85§ 

Syenytic  gneiss,  85§ 

Synbathocrinus,  602 

Synclines,  102§*,  103*,  104,  105* 

Synclinorium,  380§,  729,  731 

Syncoryne,  429*,  431 

Synedra  ulna,  164*,  165;  vitrea,  699 

Syornis,  1014 

Syria,  Cretaceous  in,  857,  859 

Syringodendron,  699 

Syringopora,  551,  552,  567,  585,  704, 
711;  bifurcata,  567,  568;  Hisin- 
geri,  591,  592  ;  Maclurii,  584*,  590, 
592;  multattenuata,  690;  multi- 
caulis,  550 ;  retiformis,  550 

Syringostroma  columnare,  590 ; 
densum,  590 

System  of  formations,  406§;  of 
Mountain  Ranges,  389;  of  the 
Rhine,  De  Beaumont's,  784 

Systemodon,  903,  918;    tapirinus, 


Tabellaria,  168, 164* 

Table  mountain  or  mesa,  185, 186*, 


Table  Mountain,  S.  Africa,  699 

Tachylyte,  87§ 

Tacoma,    Mt.,    240    (glacier),    296 

(height),  945 
Taconian,  446 

Taconic  limestone  belts,  528-531 
—  Range,  24;  making  of,  386,  527- 

532;     Cambrian    of,    467,    483; 

Lower  Silurian  of,  490,  495,  517 ; 

metamorphism  in,  309,  325 
Tamia  solium,  437§ 
Taeniaster  spinosus,  505*,  514 
Taeniophyllum,  633 
Tseniopteris,  689,  698,  704,  750,  756 ; 

latior,     756;     Lescuriana,     705; 

linnaeifolia,  749*  ;  magnifolia,  756 ; 

multinervis,  705;  Newberryana, 

705 ;  vittata,  705 
Tahiti,  thickness  of  coral  reef,  150 ; 

denudation  of,  180* ;  waterfalls  at, 

185;   tide  at,  212;   lava  streams 

thicker  toward  the.  interior,  290 
Tahitian  Islands,  map  of,  36* 
Tainoceras  cavatum,  691 
Talc,  65,  67§,  68,  79,  89,  318,  320, 453 
Talcahuano,  elevation  at,  349 
Talchir  group,  698,  699 
Talcose  schist,  89§  ;  slate,  84,  89§ 
Talpa,  927 

Tampa  limestone,  891 
Tancredia,    759,    760 ;    Americana, 

855 ;  extensa,  760  ;  Warreniana, 

758* 

Tanganyika  (Lake),  38 
Tanna  Island,  296 
Tantalum,  449 
Tape-worm,  437§ 
Tapes,  916 

Tapir,  54,  902,  981, 1002 
Tapiravus,  919 
Tapirus,  928;    Americanus,  1001; 

Arvernensis,  927 ;  Haysii,  1001 ; 

Indicus,  905*  ;  priscus,  927 
Tar,  mineral,  712 
Tarannon  shales,  563 
Tarawan  Islands.     See  Gilbert 
Tarawera  eruption,  291,  305,  374 
Tarn  (Mt.),  858 
Tasmania,    21,    415,    628,  937,  948 

(fiords) 

Taunusian,  626 
Taxinese,  596,  673 
Taxites,  777,  840,  921 ;  Olriki,  921 
Taxocrinus,  602 ;  elegans,  505*,  514 
Taxodium,  921, 922,  989 ;  cuneatum, 

838;   distichum,  921;   distichum 

Miocenum,  839 
Taylor  marls,  855 
Tchad  Lake,  34 
Tecali,  Mex.,  limestone,  138 
Technocrinus,  577 
Teeth,  composition  of,  72,  78 
Tejon  beds  or  group,  830,  831,  884, 

885,  888,  889,  916 
Teleoceras,  919 
Teleodus,  918 
Teleosaurs,  787 

Teleosaurus,  790 ;  Chapmanni,  790 
Teleosts,    418§,    869;    Cretaceous, 

812,843 
Telephus,  521 
Telerpeton  Elginense,  772*,  778 


Tellina,  916,  917;  biplicata,  917; 
Groenlandica,  984 ;  linifera,  916 

Tellinomya,  516;  alta,  514,  516; 
Angela,  500 ;  machaeriformis,  550  ; 
nasuta,  507*  ;  nucleiformis,  558 

Tellurium,  381 

Telmatherium,  918 

Temiscaming  Lake,  445 

Temiscouata  Lake,  533,  559 

Temnochilus,  675 ;  conchiferumr 
690;  crassum,  675,  676*,  690; 
depressum,  690 ;  Forbesanum, 
690 ;  latum,  690 

Temnocyon,  911,  918 

Temperature,  52,  727,  877  (change', 
exterminating  life);  in  Archaean 
time,  440,  441,  442;  in  mines, 
257 ;  of  the  ocean,  46§.  See  also- 
Climate 

Temple  of  Jupiter  Serapis,  changes 
of  level,  348,  349* 

Teneriffe,  crater  of,  277,  291 

Tennessee,  mean  height  of,  28  j 
marble,  494,  524 

—  River,  540 

Tentaculite  limestone,  535,  552,  556^ 
557,  558,  559 

Tentaculites,  556,  560 

Tentaculites,  516,  562,  568,  586,  599, 
626;  attenuatus,  592;  bellulus, 
592 ;  distans,  562 ;  elongatus,  560, 
579  ;  gracilistriatus,  592,  620,  621 ; 
gyracanthus,  556*,  557  ;  incurvus, 
514;  ornatus,  567,  568,  569;  Os- 
wegoensis,  514,  516;  Richmond- 
ensis,  514;  scalariformis,  590; 
scalaris,  625 ;  spiculus,  620  ;  Ster- 
lingensis,  514;  tenuistriatus,  516 

Tephryte,  87§ 

Terebellum  fusiforme,  926;  sopita, 
926 

Terebra,  916 ;  Houstonia,  916 ;  sim- 
plex, 917 

Terebratula,  72  (analysis),  425§, 
426*§,  756,  834,  856;  augusta,. 
757;  biplicata,  791,  865;  bovi- 
dens,  690 ;  Choctawensis,  837 ; 
digona,  779*;  diphya,  779*,  791, 
793  ;  diphyoides,  791 ;  elongata, 
707;  fimbria,  790^  fusiformis,. 
704;  gracilis,  866;  Harlani,  378r 
840*,  854;  hastata,  700*;  im- 
pressa,  425*;  Liardensis,  758;. 
perovalis,  790;  plicata,  840*,  854; 
sella,  791 ;  semisimplex,  757 ;  Sul- 
livanti,  601  ;  vitrea,  426* ;  Waco- 
ensis,  837 

Terebratula  family,  585*,  779 

Terebratulids,  922 

Terebratulina  Atlantica,  854 ;  caput- 
serpentis,  426*;  gracilis,  866; 
Guadalupae,  855 

Teredina  personata,  925 

Teredo,  158,  425 

Termites,  158 

Terrace  formation,  992 

Terrace  period,  941 

Terraces  of  rivers,  lakes,  and  sea- 
shores, 193,  194*,  228,  943,  947, 
981-994;  height  due  mostly  to 
height  xof  flood,  194.  See  also 
Flood-grounds ;  Shore  platforms 


INDEX. 


1083 


Terraces,  of  Champlain  period,  981, 
986,  986,  991* 

Terrane,  90§ 

Terranes,  61§,  89§-116;  stratified, 
90;  unstratified,  116 

Terrestrial  life  rarely  fossilized,  141, 
525 

Terrigenous,  144§ 

Terror,  Mt.,  height  of,  296 

Tertiary  era,  188,  202,  339,  347,  350, 
364-366,  380,  381,  392,  407,  408, 
409*,  411,  822,  828,  829,  831,  857, 
879  ;  subdivisions,  880 ;  N.  Amer- 
ica, 880  ;  foreign,  919 ;  general 
observations,  928;  Tertiary  ele- 
vation continued  into  Glacial 
period,  946.  See  also  Miocene; 
Pliocene 

—  eruptions,  876 ;  in  western  Amer- 
ica, 340^  igneous  outflows  in  the 
Deccan,  299 

—  fresh-water  lakes  of  N.  America, 
202,  882 

—  mountain-making,  foreign  exam- 
ples of,   367-369,   769,   812;  oro- 
genic     and     epeirogenic     move- 
ments, 932-939 ;  orographic  move- 
ments along  the  Pacific  mountain 
border,  364-366 

Teschenyte,  88§ 

Testudinates,  767,  901* 

Testudo,  901;  Atlas,  923;  bron- 
tops,  901*,  902 ;  Stricklandi,  787, 
790 

Tetrabranchs,  424§,  425*,  781,  869 
(pass  their  climax) 

Tetracoralla,  431  §,  718 

Tetractinellids,  431  §,  432* 

Tetradecapods,  420§*,  421,  423§, 
438§,  439,  525,  574,  707,  720,  721, 
724,  725 

Tetradium,  501,  505;  cellulosum, 
515;  columnare,  514;  fibratum, 
511*,  515 

Tetragraptus  bryonoides,  500 ;  fru- 
ticosus,  500 

Tetrahedrite,  335 

Tetrapterus  priscus,  925 

Texas,  mean  height  of,  23 ;  Archaean 
in,  444,  446,  447 ;  Cambrian,  464, 
466,  469,  477,  484;  Upper  Silu- 
rian, 537;  Devonian,  575,  580; 
Subcarboniferous,  637 ;  Carbonif- 
erous, 648,  690,  693 ;  Permian, 
660,  685,  687,  688;  Triassic, 
660,  746;  Cretaceous,  817,  824, 
854;  disturbances  in,  868;  Ter- 
tiary, 884,  885,  888 ;  Quaternary, 
378 

Textularia,  855 ;  globulosa,  432* 

Thalassic,  535§   • 

Thalassophyllum  clathrus,  582 

Thames  River,  Conn.,  461,  949 

Thames  River,  Eng.,  191 

Thamnastrsea,  777,  778  (number  of 
British);  concinna,  790;  gre- 
garia,  790 

Thanet  sands,  920,  925 

Thanetian  group,  925 

Theca,  481,  514,  521,  707 ;  parvius- 
cula,  514,  516 

Thecidium  family,  779 


Thecodontosaurus,  773 ;  gibbidens, 

754 

Thecodonts,  754§ 
Thecosmilia,  777,  778  (number  of 

British) ;  annulata,  790 
Thelodus  parvidens,  566*,  567 
Thelyphonus,  723 
Thenaropus  heterodactylus,  692 
Thermal  waters,  258,  305-309,  334, 

335 

Theromora,  688 
Theromores,  707 
Thian-Shan  Mts.,  32 
Thick-bedded  structure,  92§ 
Thielson,  Mt.,  266 
Thimble    Islands,  degradation   at, 

260 ;  pot-holes  of,  949 
Thinohyus,  911,  918 
Thinolite,  133* 
Thoracosaurus,  848 
Thorium,  449 
Thracia  Conradi,  983 ;  curta,  984 ; 

depressa,  791 
Thrissops,  417* 
Thrust-planes,  534 
Thuia,  840 

Thuringia,  Permian  in,  706 
Thuyites,  777 
Thysanura,  419,  702 
Thysetes  verrucosus,  567 
Tiaropsis,  429* 
Tibet,    26,    32;    Silurian    of,    868; 

Triassic  in,  770;  Jurassic,  791; 

folded  Nummulitic  beds  of,  521, 

920 ;  Mammals  of,  936 
Tiburtine,  79§ 

Ticholeptus  beds,  886,  894,  895 
Tick,  420 
Tidal  wave  and  currents,  43,  210 ; 

on  Lake  Michigan,  202 
Tide  and  currents  in  the  Cambrian, 

484 ;  Devonian,  629,  630 
Tierra  del  Fuego.    See  Fuegia 
Tile  clay,  665 
Tile-fish,  56 
Tilestones,  563,  566 
Tilibiche,  coral  limestone  at,  347 
Till,  81§,  251§ 

Tillodonts,  903,  904,  917,  918 
Tillotherium,    904,    918;     fodiens, 

904*,  905  ;  latidens,  904*,  905 
Timber  Belt  beds,  888 
Time,   geological,   subdivisions  of, 

404 ;  ratios  and  length,  1023 
Timpahute  Range,  366*,  469 
Tin,  83,  88,  336,  343 
Tinacoro  Island,  296 
Tinoceras,  907§,  918;  anceps,  907; 

grandis,  907  ;  ingens,  906*,  907 
Tinodon  bellus,  767* 
Tionesta  basin,  947 
Tipula  Carolina?,  900* 
Tipulidse,  900 
Tirolanus  Cassianus,  773 
Tisiphonia,  432* 

Titanic  acid,  86 ;  iron,  70§,  449,  450 
Titanichthys,  618 ;  Clarki,  619 
Titanite,  67§ 
Titanium,  70,  455 
Titanophasma  Fayoli,  701,  702* 
Titanosaurus,  867 
Titanotheres,  907,  908,  91)9,  918 


Titanotherium  anceps,  907  ;  gigan- 

teum,  908*,  909 
Titanotherium  beds,  886,  893,  908, 

910,  918 

Tithonian  group,  779,  791 
Titicaca,  Lake,  26,  347,  627 
Toarcian  group,  775  ;  (Upper),  790 
Tredi-Windgaellen  group  of  moun- 
tains, 367 
Tofua  Island,  296 
Toluca,  Mex.,  265 
Tom,  Mt.,  802;    Ridge,  801*,  803, 

804,  805,  806,  807 
Tombigbee  River,  885,  889  ;  sands, 

815,  823,  854 
Tomitherium,  918 
Tonga  Islands,  37,  350,  374 
Tongrian  group,  884,  926 
Tongue  River,  266 
Tonto  group  of  Gilbert,  447,  469 
Topaz,  63,  66*§,  338 
Topazolites,  312 
Torbanite,  662 
Tornoceras  mithrax,  591 
Torosaurus,  847  ;  gladius,  846* 
Toroweap  fault,  362,  363* 
Torre  del  Greco,  294 
Torres  Strait,  937 
Torrid  zone,  46§ 
Torridonian  group,  457 
Torsion,  105,  106*,  107,  371 ;  effects 

of,  in  ice,  371,  372*;   in   strata, 

105,  106*,  371 

—  as  an  explanation  of  the  zigzag 
arrangement  of  continents,  394, 
395 

Tortoises,  787 

Tortone  blue  marls,  926 

Tortonian  group,  884,  926 

Totoket  Ridge,  801*,  802,  803,  806 

Toucan,  54 

Touraine,  926 

Tourmaline,  63,   66*§,  82,  88,  160, 

312,  320;    crystals  displaced   by 

quartz,  138*  ;  rocks,  82,  83 
Tourmalyte,  88§ 
Toxaster  Campicheii,  865;  compla- 

natus,  865 

Toxoceras  bituberculatum,  862*,  865- 
Toxodon,  927 
Toyabe  Range,  365 
Tracheates,  419§ 
Trachelomonas  laevis,  163,  164* 
Trachodon  mirabilis,  846 
Trachyceras,    756;    aonoides,  774; 

Archelaus,  774  ;  balatonicum,  774 ; 

binodosum,  774 ;  Canadense,  758 ; 

Curionii,  774 ;  Reitzi,  774 ;  trino- 

dosum,  774 ;  Whitneyi,  757* 
Trachyte,  80,  84§,  86 ;  difference  in 

density  of  glass  and  stone  states. 

of,  265 ;  relation  to  granite,  814 
Tracks.     See  Footprints 
Trade  winds,  50,  51,  159,  166 
Trails.     See  Footprints 
Transition  rocks,  408§ 
Translation-waves,  213 
Trans-Pecos  region,  824,  874 
Transportation      by     currents     of 

water,  169,  189 

—  by  glaciers,  247  ;  by  waves,  222 

—  of,  and  by,  plants  and  animals,  15ft 


1084 


INDEX. 


Transylvania,  85 

Trap,  86 

—in  Connecticut  valley  Triassic, 
800 

Trapa  natans,  ash  of,  75 

Traverse  (Lake),  947 

Travertine,  79§,  131,  132*,  133 

Tree-ferns,  53,  669* 

Trees,  protection  by,  155 

Tremadictyon  reticulatum,  777* 

Tremadoc  slates,  481,  517 

Tremataster  disparilis,  646 

Trematis,  514 

Trematodiscus  Konincki,  700* 

Trematopora,  551 

Trematosaurus,  773 

Trematospira,  562 ;  multistriata, 
551,  579 

Tremolite,  67§,  79,  819,  531 

Tremolitic  limestone,  79§ 

Trends,  systems  of,  35 

Trenton,  490 

Treodopsis  appressa,  967 

Triarthrus,  515;  Beckii,  422*,  511*, 
512*,  516 

Triassic  period,  Trias,  738 ;  Ameri- 
can, 740,  746 ;  foreign,  768 

Triceratium  obtusum,  894* 

Triceratops  prorsus,  846* ;  serratus, 
846* 

Trichiulus  villosus,  691 

Trichomanites,  622 

Triconodon  mordax,  789* 

Tridymite,  64§,  84,  318,  323,  338 

Trigonarca  pulchra,  915;  Sioux- 
ensis,  855 

Trigonia,  59,  707,  759  (first  Ameri- 
can), 760,  780  (number  of 
Jurassic),  860;  aliformis,  867; 
carinata,  865;  caudata,  865; 
clavellata,  780*,  790;  Conradi, 
758*;  costata,  790,  791;  Eufau- 
lensis,  854 ;  gibbosa,  791  ;  incurva, 
791;  limbata,  866,  867;  longa, 
867;  Mortoni,  854;  navis,  792; 
paucicosta,  790;  scabricula,  865; 
Smeei,  791 ;  ventricosa,  791 

Trigonia  family,  770 

Trigonocaris  Lebescontei,  521 

Trigonocarpus,  622,  673*,  689 ; 
ornatus,  673*,  689  ;  tricuspidatus, 
673*,  689 

Trigonoceratidae,  675 

Triisodon,  917 

Trilobites,  59, 420*,  421* ;  Cambrian, 
469,  480,  482,  483,  488 ;  legs  of, 
422*,  512*  ;  young  of,  512*,  562* 

Triloculina  Josephina,  432* 

Trinidad,  Col.,  313 

Trinidad,  W.  I.,  22,  891 

Trinity  epoch  or  group,  815,  817, 
832,  834,  836,  887;  sands,  817, 
819 

Trinucleus,  422§,  520,  521 ;  concen- 
tricus,  508*,  509,  512,  515,  516, 
517,  520,  567,  569 

Triolites  Cassianus,  773 

Trionyx,  850,  926 

Triopus,  521 

Triphylite,  321 

Triplesia  primordialis,  478* 

Triplopus,  918 


Tripolyte,  81  § 

Tripriodon,  852  ;  caperatus,  853*  ; 
ccelatus,  853* 

Trisetum,  240;  subspicatum,  945 

Trispondylus,  917,  918 

Tristan  d'Acunha,  297 

Tritonium,  916 

Tritylodon,  773,  789 

Trochoceras,  515, 549,  568,  586  (last), 
591 ;  boreale,  552  ;  clio,  591 ;  cos- 
tatum,  551 ;  Desplainense,  551 ; 
eugenium,  591 ;  Halli,  515 ;  no- 
turn,  551  ;  pandum,  591 

Trocholites,  506,  520;  Ammonius, 
506,  508*,  511,  515,  516 ;  undatus, 
506,  508*,  514 

Trochonema,  514,  516,  520,  521, 
598 

Trochosmilia  striata,  916 

Trochus,  525,  780 ;  Texanus,  836 

Trogons,  923 

Troodon,  856 

Troostocrinus,  646 ;  subcylindricus, 
547*,  550 

Trophon  clathratum,  984,  995 

Tropidocaris  bicarinata,  621 

Tropidoleptus,  627  ;  carinatus,  598*, 
601 

Tropites,  756,  757 ;  subbuUatus,  774 

Truckee  Miocene,  895 

Tsien-Tang,  the  eager  of,  212,  215 

Tuba  acutissima,  917 

Tubicola,  423 

Tucubit  Mts.,  581 

Tuedian  group,  695 

Tufa,  volcanic,  80§ ;  cones  of,  270§, 
271*,  276* 

Tufa,  calcareous,  131,  132* 

Tulip  Tree,  812,  837,  879 

Tully  limestone,  576,  593,  594,  599, 
601,  603,  605 

Tunicates.     See  Ascidians 

Tunneling  by  animals,  158 

Turbinella  regina,  917;  Wilsoni, 
916 

Turbinolia  Texana,  887 

Turbo,  707,  780;  Shumardi,  591; 
solitarius,  774 

Turf,  protection  by,  155 

Turkey,  34 

Turonian  group,  815,  858,  859,  866 

Turricula  Millingtoni,  916;  polita, 
916 

Turrilepas,  567,  579,  602 ;  Canaden- 
sis,  513*  ;  Devonicus,  600* 

Turrilite,  861 

Turrilites,  771,  861;  Brazoensis, 
837  ;  catenatus,  862*,  865 ;  costa- 
tus,  866 ;  helicinus,  855 ;  pauper, 
854 ;  tuberculatus,  866 

Turritella,  824,  916,  922 ;  Alabami- 
ensis,  915;  alveata,  916;  areni- 
cola,  916  ;  cselatura,  916  ;  carinata, 
897*,  916 ;  Chipolana,  917 ;  com- 
pacta,  854;  erosa,  984;  indenta 
var.  mixta,  917 ;  Mississippiensis, 
916;  multisulcata,  926;  nasuta, 
897*,  916;  perdita,  916;  plebia, 
378 ;  prsecincta,  915 ;  pumila,  854 ; 
reticulata,  984 ;  subgrundifera, 
899*,  917;  Tampse,  898*,  916; 
vertebroides,  854 


Turtles,  415,  847;  Triassic,  772* 
773,  797 ;  Jurassic,  760,  766*,  767,' 
768,  797;  Cretaceous,  826,  849, 
856,  867  ;  Tertiary,  202,  901*,  902, 
923,  927 

Tuscaloosa  group,  815,  816,  819  } 

Tylosaurus  micromus,  849* 

Typhis,  916;  acuticosta,  917;  cur- 
virostratus,  916  ;  pungens,  926 

Typothorax  coccinarum,  758 

Tyrol,  dolomyte  of,  134 

Tysonia  Marylandica,  831 

Uinta  Eocene  lake  basin,  360*,  881*, 
882,  886,  893 

—  Mts.,  109,  360*,  365 
Uintatherium,   907§,   918;    Leidya- 

•mim,  907  ;  robustum,  907 
Uitenhage  series,  873 
Ullmannia,  693,  704 
Ulodendron,  699  ;  majus,  689 ;  punc- 

tatum,  689 
Umbone,  424 
Umbral  series,  684,  728 
Unaka  Mts.,  85 
Unakyte,  85§ 
Unartok  series,  921 
Unconformability,  114,  115*§,  116 
Unconformity,  115*§ 
Under-clay,  639,  653,  708 
Ungulates,  902,  and  beyond 
Ungulina,  621 
Unio,   612,   821,   829,  837;    Danse, 

856  ;  Deweyi,  856 ;  ebenus,  966 ; 

Liassinus,     760 ;     ligamentinus, 

966 ;  rectus,  966 ;  Valdensis,  861* 
Unio  family,  946,  950 
Uniontown  coal-bed,  651,  656 
United  States,  mean  height  of,  23 ; 

geological  map  of,  412* ;  heights 

of  the   Cretaceous    beds  of  the 

Kocky  Mountains,  933 
Untercarbon,  682 
Unterer  Wieder  Schiefer,  569 
Upernavik,  244 

Uphantaenia  Chemungensis,  611 
Upper  Pentamerus.    See  Pentame- 

rus 

—  Silurian,  535 
Uralichas  Kibeiroi,  521 
Uralite,  317 
Uralitization,  317 
Uraninite,  321 
Uranium  minerals,  821 
Uranoplosus,  836 

Urformation,    440  (Archaean    syn- 
onymy) 

Urgebirge,  440  (Archaean  synony- 
my) 

Urgneiss,  408§ 

Urgneissformation,  440  (Archaean 
synonymy) 

Urgonian,  867*,  859,  865 

Urocordylus  Wandesfordii,  704 

Urosalpinx  trossulus,  917 

Urosalpynx  cinerea,  994 

Urosthenes  australis,  698 

Urosthenic,  439,  717,  726,  796, 
931 

Ursa  stage  of  Heer,  704 

Ursus  amplidens,  1000;  Arctos, 
950,  1004, 1006 ;  Arvernensis,  927 ; 


INDEX. 


1085 


ferox,  1006 ;  pristinus,  1001 ;  spe- 
ISEUS,  1004*,  1009 

Urus,  1013 

Utah,  mean  height  of,  23;  high 
plateaus  of,  187,  386 ;  Henry  Mts. 
in,  301 ;  ore  beds  of,  338,  339*, 
340  ;  map  of,  360* 

— ,  Archaean  in,  449  ;  Cambrian, 
469,  473,  476;  Lower  Silurian, 
469,  495;  Trenton,  495;  Carbon- 
iferous, 301,  658,  674,  690;  Per- 
mian, 660  ;  Triassic,  746  ;  Jura- 
Trias,  749;  Jurassic,  747,  760; 
Cretaceous,  302,  339*,  340,  825 
(coal),  826,  829,  856 ;  post-Meso- 
zoic,  876  ;  Tertiary,  302,  365,  366, 
882,  886,  893,  901,  934 

Ute  limestone,  494 

Utica  and  Hudson  epochs,  489,  492 

Val  d'Arno,  927 

Valdivia,  51 

Valenginian,  859,  865 

Valley  drift,  946 

Valleys,  excavation  of,  180,  182 ; 
filled,  not  excavated  by  the  ocean, 
228 

Vallonia  pulchella,  966 

Valparaiso,  banded  and  other  veins, 
329*,  332*  ;  earthquake  in  1822, 
849 

Vanadate,  340 

Vancouver  Island,  23,  747;  Creta- 
ceous of,  818 ;  coal  of,  825 ;  coal- 
plants  of,  837,  840,  872 

—  Eange,  25,  812,  892 
Vanuxemia  Montrealensis,  503 
Varenna  marble,  774 

Vasum  horridum,  917;  subcapitel- 

lum,  916 

Vavau  Island,  39,  350  (elevation) 
Vegetable   kingdom,    9,    413,  414, 

434-437 

Vegetation,  protection  by,  155 
Vein-structure  of  glaciers,  243 
Veins,  327;  of  Archaean  rocks, 

449 

Veinstone,  331§ 
Veleda  lintea,  854 
Venericardia  borealis,   917 ;    plani- 

costa,  897* 

Venezuela,  31,  857  (Cretaceous) 
Veniella  Conradi,  854 ;  trapezoidea, 

854 

Ventriculites,  482*,  860 
Venus,  density  of,  16 ;  oblique  lines 

on  surface  of,  395 
Venus,  425§,  916  ;  cortinarea,  917  ; 

mercenaria,  994 ;    rugatina,  900*, 

917 

Venus's  Flower-basket,  432 
Verd -antique  marble,  68§,   77,  79, 

89§ 

Vergent  series,  728 
Vermes,  423 

Vermiceras  Crossmani,  760 
Vermicular    limerock,   555;     sand- 
stone and  shales,  637 
Vermilion  Cliffs,  187,  747 

—  group,  886 

—  Pass,  469 

—  schists,  44fl 


Vermont,  23  (height),  325,  496  ;  eo- 
lian  limestone,  517  ;  faults,  527, 
528*  ;  fossils,  309,  310,  887,  896 ; 
marbles,  524,  528 

Vertebraria,  698 

Vertebrates,  141,  404,  414,  415-418, 
424§ ;  relation  of,  to  Invertebrates, 
418;  Merosthenic,  era  of,  796; 
Urosthenic,  era  of,  796 

— ,  Lower  Silurian,  496,  509,  525 ; 
Paleozoic,  725-726 

Vesicular  rocks,  78§,  298 

Vespertine  series,  634,  728 

Vesperugo,  918 

Vesulian  group,  790 

Vesuvius  (Mt.),  85,  266*,  276,  280 

Viburnum  Goldianum,  839 

Vicksburg  epoch  (beds),  880,  884, 
889,  890,  896,  898*,  916 

Victoria,  Lake,  200 

Victoria  (province),  698,  699 

Vicuna,  54 

Vienna,  Miocene  of,  922,  939 

Viesch  glacier,  237 

View  of  the  aa  lava-stream,  287* 

View  of  alluvial  cones,  Indus  Basin, 
195* 

View  of  an  atoll,  145* 

View  of  Beehive  Geyser  in  action, 
308* 

View  of  blocks  on  the  shore-plat- 
form of  the  Paumotus,  222* 

View  (ideal)  of  Carboniferous  vege- 
tation, 666* 

View  of  cliffs,  Port  Jackson,  N.S. 
W.,  221* 

View  of  Colorado  Canon,  188* 

View  of  columnar  basalt,  Orange, 
N.J.,262* 

View  of  drop-made  and  of  rain- 
made  columns,  178* 

View  in  Elk  Mts.,  showing  up- 
turned strata,  106*,  364* 

View  of  Geyserite  Terraces,  N. 
Zeal.,  305* 

View  of  the  Gorner  Glacier,  237* 

View  of  Gothic  Mt.,  Col.,  275* 

View  of  a  high  island  with  barrier 
and  fringing  reefs,  148* 

View  of  jointed  rocks,  Cayuga  Lake, 
112* 

View  of  Juke's  Butte,  301* 

View  of  Kiama  basaltic  columns. 
261*,  262* 

ViewofKilauea,  270* 

View  of  loess  formation  on  the 
Hoang  Ho,  196* 

View  of  Mammoth  Hot  Springs, 
132* 

View  of  Marble  Canon,  187* 

View  of  the  southwest  end  of  Mok- 
katam,  160* 

View  from  Monument  Park,  illus- 
trating erosion,  186* 

View  of  Mount  Shasta,  267* 

View  of  Nanawale  cinder-cones, 
285* 

View  of  Oahu  tufa-cones,~271* 

View  of  Obsidian  Cliff,  Yellowstone 
Park,  264* 

View  of  "  The  Old  Hat,"  New  Zea- 
land, 221* 


View  of  Phonolyte  Peak,  Fernando 
de  Noronha,  263* 

View  of  plicated  clayey  layer,  209* 

View  on  Boche-Moutonnee  Creek, 
250* 

View  of  rocks  detached  by  wave- 
action,  Mount  Desert,  219*,  220* 

View  of  rocks  disrupted  by  roots  of 
trees,  157* 

View  of  sandstone  veins,  Oregon, 
844* 

View  of  Temple  of  Jupiter  Serapis, 
349* 

View  of  terraces  on  the  Connecticut 
Eiver,  194* 

View  of  trap  bluff  at  Greenfield,  805* 

View  of  tufa  deposits,  Lake  Mono, 
132* 

View  of  upturned  Cretaceous  beds 
near  Abu  Eoasch,  161* 

View  of  Vesuvius,  266* 

View  of  water-and-gas  geyser,  Pa., 
608* 

View  of  West  Eock,  804* 

Virgen,  Eio.     See  Virgin  Eiver 

Virgin  Eiver,  339,  363 

Virginia,  23  (height),  24,  125,  353, 
357,  358,  383,  387,  437,  468;  iron 
ore  beds,  127,  449;  section  of 
rocks,  355  ;  upturnings  in,  532, 
808 

Virgloria,  Virglorian,  774 

Virgulian  group,  791 

Vise  limestone,  696 

Viso,  Mt.,  266 

Vitrifiable  clay,  81  § 

Vitriol,  70 

Vitulina,  627 

Viverra,  927 

Viviparous  Mammals,  415 

Viviparus,  856 ;  fluviorum,  861* 

Volcanic  action  and  its  causes,  277- 
293 ;  reached  its  maximum  in 
later  Cretaceous  and  Tertiary, 
326 

Volcanic  ashes,  eolian  transporta- 
tion of,  80  ;  deposited  over  the 
sea  bottom,  136 

-  belt  separating  northern  and 
southern  continents,  394 

—  bombs,  287*§,  2S9§ 

—  eruptions,  earthquakes  not  essen- 
tial in,  286 

—  glass,   84§,  86,  87,  263,  264*,272- 
2S8§ 

—  mud.    See  Tufa 

—  necks,  290§ 
—rocks,  84,  272,  298 

—  vapors,  268§,  269,  277-282,   283- 
288    (passim);    work    of    spent 
vapors,  293-295 

Volcanoes,  distribution  of,  295-297  ; 
number,  297  ;  occurrence  in  lines, 
282;  of  continents  mostly  on 
their  borders,  295,  392;  conti- 
nental distinguished  from  oceanic, 
379 

— ,  carbonic  acid  from,  128,  278 

— ,  extinction  of,  290-291 ;  interior 
of,  before  and  after  extinction, 
290,  291 

Volga,  88 


1086 


INDEX. 


Volgian,  760,  790 

Volsella  scalpra,  760 

Voltzia,  T50,  774 ;  heterophylla,  698, 

770*,  773 

Voluntomorpha  Eufaulensis,  854 
Voluta,  922 ;  ambigua,  926 ;  athleta, 

926 ;  Newcombiana,  915 ;  nodosa, 

925;    Showalteri,   915;    Wether- 

ellii,  925 
Yolutilithes  Haleanus,  916 ;  limop- 

sis,  896*,  915 ;  rugatus,  896*,  915 
Vosges,  310,  626,  734  (upturnings), 

738  ;    Archaean  in,  456 ;  Triassic, 

768 

Vosgian,  738,  769,  773 
Vraconnian,  859 
Vulcano,  276 

Waagenoceras,  686 

Wabash  River,  947 

Wachita  Mts.    See  Ouachita 

Wacke,  80§,  408 

Waders,  141  (easily  fossilized),  852, 
902 

Wadesboro  Triassic  area,  741 

Walderthon,  865 

Wairoa  series,  770 

Wakes  Island,  38 

Walchia,  693,  699,  704,  750 ;  pini- 
formis,  699,  704,  705* 

Waldheimia,  59 ;  compacta,  690 ; 
digona,  790 ;  humeralis,  791 

Wales,  173, 191,  370, 463, 464 ;  erup- 
tions in,  518 ;  upturnings  in,  534, 
783  ;  geological  map  of,  694* 

— ,  Archaean  in,  456, 457  ;  Cambrian, 
457,  480,  481;  Lower  Silurian, 
517,  518,  520;  Upper  Silurian, 
563,  564,  568,  574 ;  Devonian,  622, 
625  ;  Subcarboniferous,  695 ;  Car- 
boniferous, 322,  662,  693,  694*, 
695,  696,  734 ;  Permian,  734 ;  Tri- 
assic, 768 

Walker's  Lake,  757 

Wallala  beds,  830,  840 

Walnut  clays,  817 ;  sands,  886 

Warrior  coal-fields,  648,  657 

Warsaw  group,  634,  637,  638 

Wasatch  Eocene  basin  or  lake,  360*, 

361,  865,  881*,  882,  893 
—  limestone,  580,  581,  659 
Wasatch  Eange,  24,  25,  340,  359, 

360*  (map),  874 

— ,  Archaean  in,  444, 447;  Cambrian, 
469 ;  Trenton,  494 ;  Upper  Silu- 
rian, 541 ;  Devonian,  360*,  361, 

362,  580,    581;     Carboniferous, 
360*,    361,  362;    Mesozoic,  380; 
Triassic,  747  ;  Jurassic,  747,  760  ; 
Cretaceous,  360*,  361 ;  post-Mes- 
ozoic,    874,  875;    Tertiary,  365, 
366,  934 

Washakie  group  or  basin,  886,  893 
Washburn,  Mt.,  276,  296  (height) 
Washington,  Mt.,  Mass.,  104,  105*, 

528,  530 
Washington,  state,  mean  height  of, 

23 ;  glaciers  of,  240 ;  volcanoes  of, 

296, 937 ;  coal  of,  831 ;  Tertiary  in, 

885,  892 
Washita  epoch  or  group,  815,  817, 

819,  886  ;  limestone,  817,  887 


Water,  arrangement  of  seas,  16; 
composition  of,  71§ ;  character- 
istics of,  170-171;  amount  ab- 
sorbed within  the  earth,  209; 
freezing  and  frozen :  glaciers  and 
icebergs,  118,  171,  230-253 

—  as  a  chemical  agent,  118;  as  a 
solvent,  118,  119,  121,  122 ;  chem- 
ical absorption  of,  128;   carbonic 
acid  in  rain,  river,  and  sea,  128 

Water-lime  group,  410,  535, 552, 553, 
554,  555,  556,  558,  559,  570,  571, 
606;  American  species  occurring 
elsewhere,  569 

Water-line  of  coasts,  346 

Water-sculpture  of  mountains,  185§, 
186* 

Water-spout,  163 

Waterfalls,  174,  184,  185 ;  in  glacier 
Crevasses,  250 

Waterglass,  135§ 

Wave-marks,  94§,  538 

Waverly  group,  604,  638 

Waves,  action  and  force  of,  210,  212 ; 
height  of,  213,  216 ;  limit  of  de- 
nudation by,  219,  221.  See  also 
Tidal  wave 

Waynesburg  coal-beds,  651, 657, 663, 
677 

Weald  axis,  936 

Wealden  epoch,  858 

Weasel,  924 

Weathering,  128,  136 

Weber,  360*,  361,  362 

—  conglomerate,     659 ;    quartzyte, 
659 

Weevils,  771 
Weissliegende,  697 
Wellenkalk,  769,  773 
Wellington  Strait,  544,  552 
Wells.    See  Artesian  ;  Mineral  oil 
Welwitschia,    435,    674;    mirabilis, 

435* 

Wengen  shales,  774 
Wenlock  Edge,  Scotland,  534 

—  group,  463,  519,  563,  564,  565,  566, 
567,  568 

—  limestone,  563 ;  shale,  563 
Werfen  (Werfenian)  beds,  769,  773 
Wernerite,  65§ 

West  Humboldt.    See  Humboldt 

West  India  basin,  857 

West  Indies,  19,  21,  22,  40  (trends), 
145  (coral  reefs),  153,  296  (volca- 
noes), 428,  429,  431,  578,  891  (Mio- 
cene) 

West  Peak,  Col.,  266 

West  River,  227 

West  Rock  dike  and  Eidge,  299*, 
302*,  303,  801*,  802,  803,  804* 
(view),  805,  806,  808 

West  Virginia,  height  of,  23 ;  min- 
eral oil  in,  607,  608 

Western  border  region.  See  Pacific 
border 

Western  Continental  Interior  (sea) 
of  N.  America,  575,  580,  635,  739, 
872 ;  Triassic  and  Jurassic  in, 
746-749,  756-768 ;  Cretaceous, 
818*,  814,  867,  873,  880 ;  Tertiary, 
880 

Western  Isles  of  Scotland,  288 


Westphalia,  627 ;  coal-beds,  696 

Wetterstein,  774 

Whale-bone  Whales,  912*§,  925 

Whales,  56,  144,  415,  902,  908,  912, 
927  (toothed),  931 ;  ear-bones  of, 
dredged,  144 

Whetstone,  80§ 

Whip-snake,  682 

White  ants,  159 

White  Bluff  bed,  889 

White  Cliff  group,  747 

White  Fish  River,  445 

White  Island,  eruption,  374 

White  Lias,  774,  790 

White  Mts.,  N.  H.,  landslide  in,  208  ; 
incipient  glacier  in,  234;  Arctic 
plants  of,  945,  946 

White  Pine  district,  495 

White  River,  894,  901 

White  River  beds,  884,  886,  893 

White  Sea,  521,  768 

Whitfieldella  didyma,  567;  nitida, 
548*,  551 ;  oblata,  549 

Whitney,  Mt.,  810 

Whittleseya,  689 ;  elegans,  674 

Whortleberry,  921 

Wianamatta  shale,  699 

Wichita,  660 

Wight,  Isle  of,  920,  926 

Wild  Boar,  54,  902,  927 

Willamette  River,  30 

Willoughby,  Mt.,  945 

Willow,  837,  859,  879 

Willow  Creek  beds,  830 

Willow  River  limestone,  493 

Wind,  89  ;  denudation  by,  159 

Wind-drift  coral  rocks,  151 ;  struc- 
ture, 93*§,  162 

Wind-made  waves  and  currents, 
166,  212,  216 

Wind  River  basin  and  group,  884, 
886,  893,  918;  Mts.,  240  (glaciers), 
639,  748,  945 

Windsor  series,  639 

Windward  Islands,  44 

Winnipeg  Lake,  29,  199,  200,  515, 
524,  552;  climate  of,  944;  dis- 
charge into  the  Mississippi,  947 ; 

.  in  the  Champlain  period,  985 

Winnipegosis  (Lake),  594 

Winooski  limestone,  467,  472 

Wisconsin,  23  (height),  536,  944 
(rainfall)  ;  lead  mines,  842,  522 

Wodnika  striatula,  707 

Wolf,  924,  927 

Wolf  Creek  conglomerate,  605 

Wood  brought  down  by  rivers,  191 ; 
carbonized,  892;  composition  of, 
74,  123,  713;  decomposition  of, 
123,  124,  613;  silicified,  125,  135, 
143,  280,  300,  892  (see  also  Petri- 
factions) 

Woodchuck,  915 

Woodocrinus  elegans,  640*,  646 

Woodpecker,  902 

Wood1  s  Bluff  beds,  888 

Woodville  sandstone,  657 

Woodwardia  latiloba,  839 

Woolhope  beds,  563 

Woolwich  beds,  925 

Worcester,  Mass.,  453,  461,  633, 
635,  646,  658,  714,  732 


INDEX. 


1087 


Worm-burrows,  Archaean,  446; 
Cambrian,  464,  470,  477*,  480; 
Hamilton,  593 

Worms,  Sea,  59  ;  trails  of,  95 ;  work 
of  common  earth-,  156 ;  charac- 
teristics of,  418,  419,  420*,  423§, 
437;  Cambrian,  469,  474,  477*, 
487 

Wrangel  Bay,  747 

Wright,  Mt.,  238 

Writing  slate.    See  Koofing  slate 

Wyoming,  height  of,  23,  29,  85, 
338,  360,  365,  808  ;  Archaean,  449  ; 
Cambrian,  466,  476  ;  Subcfirbonif- 
erous,  639  ;  Coal-measures,  662  ; 
Triassic,  746,  747  ;  Jurassic,  748, 
760,  761,  763,  767,  768;  Creta- 
ceous, 825  (coal),  826,  828  (coal). 
845,  847,  848,  849,  876 ;  Tertiary, 
882,  886,  893,  894,  906,  907 ;  Gla- 
cial, 945 

Xanthidia,  582,  583*,  859 
Xenoneura  antiquorum,  600* 
Xiphodon,  924,  926  ;  gracilis,  924*, 

926 
Xylobius,  701 ;    fractus,  691 ;   Ma- 

zonus,  691 ;    similis,  691 ;  sigilla- 

rise,  678*,  682,  691,  703 
Xystrodus,  692 

Yablonoi  Mts.,  32 
Yang-tse-Kiang,  30,  198 
Yellow  ocher,  71  §,  126 


Yellow  Eiver,  China.  See  Hoang 
Ho 

Yellow  Sea,  198 

Yellowstone  Lake,  200,  306 

Yellowstone  National  Park,  29,  30  ; 
geysirite,  82,  152 ;  Obsidian  cliff, 
84,  263;  Death  Gulch  in,  128; 
calcareous  deposits  or  travertine, 
79,  131,  152 ;  volcanic  peaks  of, 
296;  lithophyses  in,  337;  time 
of  eruptions,  876,  937 ;  geyser 
region,  hot  springs,  etc.,  135,  305, 
300* ;  siliceous  Algae,  152 

Yellowstone  Elver,  29,  266,  830, 
937 

Yenisei  Eiver,  30 

Yews,  53,  435,  596,  639,  666,  673, 
685,  718,  735 

Yoldia,  760,  917 ;  arctica,  984,  995, 
997;  Claibornensis,  915;  eborea, 
915;  glacialis,  983,  984;  limatula, 
917,  984 ;  sapotilla,  917 

Yoredale  group,  695 

Yorktown  epoch,  884,  891,  899* 

Yosemite  domes,  origin  of,  260 

Yosemite  valley,  810 

Ypresian  group,  925 

Yttrium,  449 

Yucatan,  40,  44 

Yukon  district,  818,  868 

Zambesi  Eiver,  30,  33 

Zamia,  434,  750 

Zamites  acutipennis,  833,  834 ;  aper- 


tus,  834 ;  borealis,  834 ;  Montana, 
833,  834 ;  occidentals,  756 

Zanclean  beds,  927 

Zanskar  district,  456,  791 

Zanzibar,  83 

Zaphrentis,  515,  516,  551,  552,  562, 
579,  591,  597,  611,  640,  674,  700, 
718  ;  bilateralis,  545*,  550  ;  Cana- 
densis,  515  ;  Edwardsi,  590  ;  gi- 
gantea,  584*,  590,  591  ;  Halli,  601  ; 
minas,  646;  prolifica,  590;  Rafi- 
nesquii,  584*,  590  ;  simplex,  601 ; 
spinulosa,  646 

Zeacrinus,  646,  690 

Zebra,  54 

Zechstein,  697,  707 

Zeolites,  68,  78,  312 ;  at  Plombieres, 
323  ;  origin  of,  336 

Zermatt,  glacier  of,  237* 

Zero-strain,  depth  of,  3S4,  385,  387 

Zeuglodon,  822,  908§,  912,  923,  931  ; 
cetoides,  908* 

Zinc  ores,  70,  340,  342,  449,  542 

Ziphias,  144 

Zircon,  67  §,  85,  455 ;  syenyte,  85§, 
447 

Zirconia,  67 

Zirconitic  granite,  83 

Zirconium,  449 

Zizyphus  fibrillosus,  839 

Zoantharia,  431  § 

Zoisite,  66§,  88,  318 

Zones,  407§ 

Zygospira  modesta,  514,  516 


CORRIGENDA    AND    ADDENDA. 

Page    93,     Fig.  62  should  be  inverted. 

"     237,     3d  line  from  foot,  for  "  Lauterarr,"  read  "  Lauteraar." 
"     525,     13th  line,  for  "  Area,"  read  "  Area." 
"     572,     25th  line,  for  "  geanticline,"  read  "  geosyncline." 
"     716,     25th  line,  after  "was,"  read  "much  longer  than  Neopaleozoic ; "" 
27th  line,  for  "6:1:2:2,"  read  "7  (or  8):1:2:2;"  also  add  to 
the  paragraph  :     "The  Eopaleozoic,  as  has  been  shown  (pages 
509,  520),  continued  on  after  the  first  appearance  of  Fishes  and 
Insects,  types  that  were  formerly  supposed   to  date  from  the 
Devonian." 

"     988,     9th  line,  after  "1895,"  add  "  and  F.  B.  Taylor,  Am.  Jour.  Sc.t  1895." 
"  1036,     add:  "The  Memoir  by  E.  Dubois  on  Pithecanthropus  erectus  is. 
noticed  in  the  number  of  the  Am.  Jour.  Sc.  for  February,  1895." 


1088 


USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

EARTH  SCIENCES  LIBRARY 
TEL:  642-2997 

This  book  is  due  on  the  last  date  stamped  below,  or 

oo  the  date'to  which  renewed. 
Renewed  books  are  subject  to  immediate  recall. 


•MAR  i    1074- 


LD21-35m-8,'72 
(Q4189S10)476 — A-32 


General  Library 

University  of  California 

Berkeley 


YD 


I 


